Abnormally low BLOOD PRESSURE that can result in inadequate blood flow to the brain and other vital organs. Common symptom is DIZZINESS but greater negative impacts on the body occur when there is prolonged depravation of oxygen and nutrients.
Procedure in which arterial blood pressure is intentionally reduced in order to control blood loss during surgery. This procedure is performed either pharmacologically or by pre-surgical removal of blood.
A significant drop in BLOOD PRESSURE after assuming a standing position. Orthostatic hypotension is a finding, and defined as a 20-mm Hg decrease in systolic pressure or a 10-mm Hg decrease in diastolic pressure 3 minutes after the person has risen from supine to standing. Symptoms generally include DIZZINESS, blurred vision, and SYNCOPE.
Reduction of CEREBROSPINAL FLUID pressure characterized clinically by HEADACHE which is maximal in an upright posture and occasionally by an abducens nerve palsy (see ABDUCENS NERVE DISEASES), neck stiffness, hearing loss (see DEAFNESS); NAUSEA; and other symptoms. This condition may be spontaneous or secondary to SPINAL PUNCTURE; NEUROSURGICAL PROCEDURES; DEHYDRATION; UREMIA; trauma (see also CRANIOCEREBRAL TRAUMA); and other processes. Chronic hypotension may be associated with subdural hematomas (see HEMATOMA, SUBDURAL) or hygromas. (From Semin Neurol 1996 Mar;16(1):5-10; Adams et al., Principles of Neurology, 6th ed, pp637-8)
Transient reduction in blood pressure levels immediately after exercises that lasts 2-12 hours. The reduction varies but is typically 5-20 mm Hg when compared to pre-exercise levels. It exists both in normotensive and hypertensive individuals and may play a role in excercise related PHYSIOLOGIC ADAPTATION.
A nicotinic antagonist that has been used as a ganglionic blocker in hypertension, as an adjunct to anesthesia, and to induce hypotension during surgery.
Cardiac arrhythmias that are characterized by excessively slow HEART RATE, usually below 50 beats per minute in human adults. They can be classified broadly into SINOATRIAL NODE dysfunction and ATRIOVENTRICULAR BLOCK.
The number of times the HEART VENTRICLES contract per unit of time, usually per minute.
A phenethylamine found in EPHEDRA SINICA. PSEUDOEPHEDRINE is an isomer. It is an alpha- and beta-adrenergic agonist that may also enhance release of norepinephrine. It has been used for asthma, heart failure, rhinitis, and urinary incontinence, and for its central nervous system stimulatory effects in the treatment of narcolepsy and depression. It has become less extensively used with the advent of more selective agonists.
Procedure in which an anesthetic is injected directly into the spinal cord.
A variety of anesthetic methods such as EPIDURAL ANESTHESIA used to control the pain of childbirth.
The movement and the forces involved in the movement of the blood through the CARDIOVASCULAR SYSTEM.
Diseases of the parasympathetic or sympathetic divisions of the AUTONOMIC NERVOUS SYSTEM; which has components located in the CENTRAL NERVOUS SYSTEM and PERIPHERAL NERVOUS SYSTEM. Autonomic dysfunction may be associated with HYPOTHALAMIC DISEASES; BRAIN STEM disorders; SPINAL CORD DISEASES; and PERIPHERAL NERVOUS SYSTEM DISEASES. Manifestations include impairments of vegetative functions including the maintenance of BLOOD PRESSURE; HEART RATE; pupil function; SWEATING; REPRODUCTIVE AND URINARY PHYSIOLOGY; and DIGESTION.
A pathological condition manifested by failure to perfuse or oxygenate vital organs.
A state characterized by loss of feeling or sensation. This depression of nerve function is usually the result of pharmacologic action and is induced to allow performance of surgery or other painful procedures.
Sepsis associated with HYPOTENSION or hypoperfusion despite adequate fluid resuscitation. Perfusion abnormalities may include, but are not limited to LACTIC ACIDOSIS; OLIGURIA; or acute alteration in mental status.
An ethanolamine derivative that is an adrenergic alpha-1 agonist. It is used as a vasoconstrictor agent in the treatment of HYPOTENSION.
The circulation of blood through the BLOOD VESSELS of the BRAIN.
The force that opposes the flow of BLOOD through a vascular bed. It is equal to the difference in BLOOD PRESSURE across the vascular bed divided by the CARDIAC OUTPUT.
A powerful vasodilator used in emergencies to lower blood pressure or to improve cardiac function. It is also an indicator for free sulfhydryl groups in proteins.
Abnormally low intraocular pressure often related to chronic inflammation (uveitis).
The volume of BLOOD passing through the HEART per unit of time. It is usually expressed as liters (volume) per minute so as not to be confused with STROKE VOLUME (volume per beat).
An abnormally low volume of blood circulating through the body. It may result in hypovolemic shock (see SHOCK).
Inorganic salts of the hypothetical acid, H3Fe(CN)6.
A transient loss of consciousness and postural tone caused by diminished blood flow to the brain (i.e., BRAIN ISCHEMIA). Presyncope refers to the sensation of lightheadedness and loss of strength that precedes a syncopal event or accompanies an incomplete syncope. (From Adams et al., Principles of Neurology, 6th ed, pp367-9)
A progressive neurodegenerative condition of the central and autonomic nervous systems characterized by atrophy of the preganglionic lateral horn neurons of the thoracic spinal cord. This disease is generally considered a clinical variant of MULTIPLE SYSTEM ATROPHY. Affected individuals present in the fifth or sixth decade with ORTHOSTASIS and bladder dysfunction; and later develop FECAL INCONTINENCE; anhidrosis; ATAXIA; IMPOTENCE; and alterations of tone suggestive of basal ganglia dysfunction. (From Adams et al., Principles of Neurology, 6th ed, p536)
A degenerative disease of the AUTONOMIC NERVOUS SYSTEM that is characterized by idiopathic ORTHOSTATIC HYPOTENSION and a greatly reduced level of CATECHOLAMINES. No other neurological deficits are present.
The injection of autologous blood into the epidural space either as a prophylactic treatment immediately following an epidural puncture or for treatment of headache as a result of an epidural puncture.
The position or attitude of the body.
Complications that affect patients during surgery. They may or may not be associated with the disease for which the surgery is done, or within the same surgical procedure.
Leakage and accumulation of CEREBROSPINAL FLUID in the subdural space which may be associated with an infectious process; CRANIOCEREBRAL TRAUMA; BRAIN NEOPLASMS; INTRACRANIAL HYPOTENSION; and other conditions.
A standard and widely accepted diagnostic test used to identify patients who have a vasodepressive and/or cardioinhibitory response as a cause of syncope. (From Braunwald, Heart Disease, 7th ed)
Pressure within the cranial cavity. It is influenced by brain mass, the circulatory system, CSF dynamics, and skull rigidity.
Drugs used to cause constriction of the blood vessels.
Acute hemorrhage or excessive fluid loss resulting in HYPOVOLEMIA.
The HEART and the BLOOD VESSELS by which BLOOD is pumped and circulated through the body.
Therapy whose basic objective is to restore the volume and composition of the body fluids to normal with respect to WATER-ELECTROLYTE BALANCE. Fluids may be administered intravenously, orally, by intermittent gavage, or by HYPODERMOCLYSIS.
Bleeding or escape of blood from a vessel.
The thoracolumbar division of the autonomic nervous system. Sympathetic preganglionic fibers originate in neurons of the intermediolateral column of the spinal cord and project to the paravertebral and prevertebral ganglia, which in turn project to target organs. The sympathetic nervous system mediates the body's response to stressful situations, i.e., the fight or flight reactions. It often acts reciprocally to the parasympathetic system.
The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)
Volume of circulating BLOOD. It is the sum of the PLASMA VOLUME and ERYTHROCYTE VOLUME.
Extraction of the FETUS by means of abdominal HYSTEROTOMY.
An alpha-2 adrenergic agonist that has both central and peripheral nervous system effects. Its primary clinical use is as an antihypertensive agent.
Procedure in which an anesthetic is injected into the epidural space.
The ENTERIC NERVOUS SYSTEM; PARASYMPATHETIC NERVOUS SYSTEM; and SYMPATHETIC NERVOUS SYSTEM taken together. Generally speaking, the autonomic nervous system regulates the internal environment during both peaceful activity and physical or emotional stress. Autonomic activity is controlled and integrated by the CENTRAL NERVOUS SYSTEM, especially the HYPOTHALAMUS and the SOLITARY NUCLEUS, which receive information relayed from VISCERAL AFFERENTS.
The study of systems, particularly electronic systems, which function after the manner of, in a manner characteristic of, or resembling living systems. Also, the science of applying biological techniques and principles to the design of electronic systems.
Solutions having the same osmotic pressure as blood serum, or another solution with which they are compared. (From Grant & Hackh's Chemical Dictionary, 5th ed & Dorland, 28th ed)
Receptors in the vascular system, particularly the aorta and carotid sinus, which are sensitive to stretch of the vessel walls.
An alpha-1 adrenergic agonist used as a mydriatic, nasal decongestant, and cardiotonic agent.
Precursor of epinephrine that is secreted by the adrenal medulla and is a widespread central and autonomic neurotransmitter. Norepinephrine is the principal transmitter of most postganglionic sympathetic fibers and of the diffuse projection system in the brain arising from the locus ceruleus. It is also found in plants and is used pharmacologically as a sympathomimetic.
The flow of BLOOD through or around an organ or region of the body.
Elements of limited time intervals, contributing to particular results or situations.
A response by the BARORECEPTORS to increased BLOOD PRESSURE. Increased pressure stretches BLOOD VESSELS which activates the baroreceptors in the vessel walls. The net response of the CENTRAL NERVOUS SYSTEM is a reduction of central sympathetic outflow. This reduces blood pressure both by decreasing peripheral VASCULAR RESISTANCE and by lowering CARDIAC OUTPUT. Because the baroreceptors are tonically active, the baroreflex can compensate rapidly for both increases and decreases in blood pressure.
The circulation of blood through the BLOOD VESSELS supplying the abdominal VISCERA.
An imidazoline sympatholytic agent that stimulates ALPHA-2 ADRENERGIC RECEPTORS and central IMIDAZOLINE RECEPTORS. It is commonly used in the management of HYPERTENSION.
The physiological widening of BLOOD VESSELS by relaxing the underlying VASCULAR SMOOTH MUSCLE.
The porcine antidiuretic hormone (VASOPRESSINS). It is a cyclic nonapeptide that differs from ARG-VASOPRESSIN by one amino acid, containing a LYSINE at residue 8 instead of an ARGININE. Lys-vasopressin is used to treat DIABETES INSIPIDUS or to improve vasomotor tone and BLOOD PRESSURE.
The relationship between the dose of an administered drug and the response of the organism to the drug.
Any liquid used to replace blood plasma, usually a saline solution, often with serum albumins, dextrans or other preparations. These substances do not enhance the oxygen- carrying capacity of blood, but merely replace the volume. They are also used to treat dehydration.
Loss of consciousness due to a reduction in blood pressure that is associated with an increase in vagal tone and peripheral vasodilation.
The long-term (minutes to hours) administration of a fluid into the vein through venipuncture, either by letting the fluid flow by gravity or by pumping it.
A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.
A synthetic mineralocorticoid with anti-inflammatory activity.
Forced expiratory effort against a closed GLOTTIS.
Therapy for the insufficient cleansing of the BLOOD by the kidneys based on dialysis and including hemodialysis, PERITONEAL DIALYSIS, and HEMODIAFILTRATION.
A direct-acting vasodilator that is used as an antihypertensive agent.
A stable, non-explosive inhalation anesthetic, relatively free from significant side effects.
Injections made into a vein for therapeutic or experimental purposes.
A widely used local anesthetic agent.
An involuntary movement or exercise of function in a part, excited in response to a stimulus applied to the periphery and transmitted to the brain or spinal cord.
The posture of an individual lying face up.
Observation of a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group.
Procedure in which patients are induced into an unconscious state through use of various medications so that they do not feel pain during surgery.
Persistently high systemic arterial BLOOD PRESSURE. Based on multiple readings (BLOOD PRESSURE DETERMINATION), hypertension is currently defined as when SYSTOLIC PRESSURE is consistently greater than 140 mm Hg or when DIASTOLIC PRESSURE is consistently 90 mm Hg or more.
Drugs used to cause dilation of the blood vessels.
A condition caused by the failure of body to dissipate heat in an excessively hot environment or during PHYSICAL EXERTION in a hot environment. Contrast to HEAT EXHAUSTION, the body temperature in heat stroke patient is dangerously high with red, hot skin accompanied by DELUSIONS; CONVULSIONS; or COMA. It can be a life-threatening emergency and is most common in infants and the elderly.
An acute hypersensitivity reaction due to exposure to a previously encountered ANTIGEN. The reaction may include rapidly progressing URTICARIA, respiratory distress, vascular collapse, systemic SHOCK, and death.
Abnormally rapid heartbeat, usually with a HEART RATE above 100 beats per minute for adults. Tachycardia accompanied by disturbance in the cardiac depolarization (cardiac arrhythmia) is called tachyarrhythmia.
The constant checking on the state or condition of a patient during the course of a surgical operation (e.g., checking of vital signs).
The restoration to life or consciousness of one apparently dead. (Dorland, 27th ed)
Method for determining the circulating blood volume by introducing a known quantity of foreign substance into the blood and determining its concentration some minutes later when thorough mixing has occurred. From these two values the blood volume can be calculated by dividing the quantity of injected material by its concentration in the blood at the time of uniform mixing. Generally expressed as cubic centimeters or liters per kilogram of body weight.
The blood pressure in the ARTERIES. It is commonly measured with a SPHYGMOMANOMETER on the upper arm which represents the arterial pressure in the BRACHIAL ARTERY.
Measurement of oxygen and carbon dioxide in the blood.
Evaluation undertaken to assess the results or consequences of management and procedures used in combating disease in order to determine the efficacy, effectiveness, safety, and practicability of these interventions in individual cases or series.
X-ray visualization of the spinal cord following injection of contrast medium into the spinal arachnoid space.
Volume of PLASMA in the circulation. It is usually measured by INDICATOR DILUTION TECHNIQUES.
A nonflammable, halogenated, hydrocarbon anesthetic that provides relatively rapid induction with little or no excitement. Analgesia may not be adequate. NITROUS OXIDE is often given concomitantly. Because halothane may not produce sufficient muscle relaxation, supplemental neuromuscular blocking agents may be required. (From AMA Drug Evaluations Annual, 1994, p178)
The combination of hemodialysis and hemofiltration either simultaneously or sequentially. Convective transport (hemofiltration) may be better for removal of larger molecular weight substances and diffusive transport (hemodialysis) for smaller molecular weight solutes.
The processes whereby the internal environment of an organism tends to remain balanced and stable.
The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.
The symptom of PAIN in the cranial region. It may be an isolated benign occurrence or manifestation of a wide variety of HEADACHE DISORDERS.
The blood pressure in the central large VEINS of the body. It is distinguished from peripheral venous pressure which occurs in an extremity.
Agents having as their major action the interruption of neural transmission at nicotinic receptors on postganglionic autonomic neurons. Because their actions are so broad, including blocking of sympathetic and parasympathetic systems, their therapeutic use has been largely supplanted by more specific drugs. They may still be used in the control of blood pressure in patients with acute dissecting aortic aneurysm and for the induction of hypotension in surgery.
A free radical gas produced endogenously by a variety of mammalian cells, synthesized from ARGININE by NITRIC OXIDE SYNTHASE. Nitric oxide is one of the ENDOTHELIUM-DEPENDENT RELAXING FACTORS released by the vascular endothelium and mediates VASODILATION. It also inhibits platelet aggregation, induces disaggregation of aggregated platelets, and inhibits platelet adhesion to the vascular endothelium. Nitric oxide activates cytosolic GUANYLATE CYCLASE and thus elevates intracellular levels of CYCLIC GMP.
An autosomal disorder of the peripheral and autonomic nervous systems limited to individuals of Ashkenazic Jewish descent. Clinical manifestations are present at birth and include diminished lacrimation, defective thermoregulation, orthostatic hypotension (HYPOTENSION, ORTHOSTATIC), fixed pupils, excessive SWEATING, loss of pain and temperature sensation, and absent reflexes. Pathologic features include reduced numbers of small diameter peripheral nerve fibers and autonomic ganglion neurons. (From Adams et al., Principles of Neurology, 6th ed, p1348; Nat Genet 1993;4(2):160-4)
Antidiuretic hormones released by the NEUROHYPOPHYSIS of all vertebrates (structure varies with species) to regulate water balance and OSMOLARITY. In general, vasopressin is a nonapeptide consisting of a six-amino-acid ring with a cysteine 1 to cysteine 6 disulfide bridge or an octapeptide containing a CYSTINE. All mammals have arginine vasopressin except the pig with a lysine at position 8. Vasopressin, a vasoconstrictor, acts on the KIDNEY COLLECTING DUCTS to increase water reabsorption, increase blood volume and blood pressure.
The active sympathomimetic hormone from the ADRENAL MEDULLA. It stimulates both the alpha- and beta- adrenergic systems, causes systemic VASOCONSTRICTION and gastrointestinal relaxation, stimulates the HEART, and dilates BRONCHI and cerebral vessels. It is used in ASTHMA and CARDIAC FAILURE and to delay absorption of local ANESTHETICS.
A potent narcotic analgesic, abuse of which leads to habituation or addiction. It is primarily a mu-opioid agonist. Fentanyl is also used as an adjunct to general anesthetics, and as an anesthetic for induction and maintenance. (From Martindale, The Extra Pharmacopoeia, 30th ed, p1078)
A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain.
Anesthesia caused by the breathing of anesthetic gases or vapors or by insufflating anesthetic gases or vapors into the respiratory tract.

Nitric oxide limits the eicosanoid-dependent bronchoconstriction and hypotension induced by endothelin-1 in the guinea-pig. (1/1770)

1. This study attempts to investigate if endogenous nitric oxide (NO) can modulate the eicosanoid-releasing properties of intravenously administered endothelin-1 (ET-1) in the pulmonary and circulatory systems in the guinea-pig. 2. The nitric oxide synthase blocker N(omega)-nitro-L-arginine methyl ester (L-NAME; 300 microM; 30 min infusion) potentiated, in an L-arginine sensitive fashion, the release of thromboxane A2 (TxA2) stimulated by ET-1, the selective ET(B) receptor agonist IRL 1620 (Suc-[Glu9,Ala11,15]-ET-1(8-21)) or bradykinin (BK) (5, 50 and 50 nM, respectively, 3 min infusion) in guinea-pig isolated and perfused lungs. 3. In anaesthetized and ventilated guinea-pigs intravenous injection of ET-1 (0.1-1.0 nmol kg(-1)), IRL 1620 (0.2-1.6 nmol kg(-1)), BK (1.0-10.0 nmol kg(-1)) or U 46619 (0.2-5.7 nmol kg(-1)) each induced dose-dependent increases in pulmonary insufflation pressure (PIP). Pretreatment with L-NAME (5 mg kg(-1)) did not change basal PIP, but increased, in L-arginine sensitive manner, the magnitude of the PIP increases (in both amplitude and duration) triggered by each of the peptides (at 0.25, 0.4 and 1.0 nmol kg(-1), respectively), without modifying bronchoconstriction caused by U 46619 (0.57 nmol kg(-1)). 4. The increases in PIP induced by ET-1, IRL 1620 (0.25 and 0.4 nmol kg(-1), respectively) or U 46619 (0.57 nmol kg(-1)) were accompanied by rapid and transient increases of mean arterial blood pressure (MAP). Pretreatment with L-NAME (5 mg kg(-1); i.v. raised basal MAP persistently and, under this condition, subsequent administration of ET-1 or IRL 1620, but not of U-46619, induced hypotensive responses which were prevented by pretreatment with the cyclo-oxygenase inhibitor indomethacin. 5. Thus, endogenous NO appears to modulate ET-1-induced bronchoconstriction and pressor effects in the guinea-pig by limiting the peptide's ability to induce, possibly via ET(B) receptors, the release of TxA2 in the lungs and of vasodilatory prostanoids in the systemic circulation. Furthermore, it would seem that these eicosanoid-dependent actions of ET-1 in the pulmonary system and on systemic arterial resistance in this species are physiologically dissociated.  (+info)

The Janus-faced aspect of 'dry weight'. (2/1770)

BACKGROUND: The goal of haemodialysis treatment in end-stage renal disease (ESRD) patients is to correct the complications of the uraemic condition. Among the main complications are fluid overload and subsequent hypertension that are corrected by achievement of 'dry weight'. We report in this study the evolution of post-dialysis body-weight and blood pressure in patients who began their HD treatment in our unit. METHODS: We studied the monthly evolution of post-dialysis body-weight (expressed as a percentage of pre-dialysis body-weight at the first HD treatment) and predialysis mean arterial pressure (MAP) over 24 months in 61 patients (21 females, mean age 59.8 years; 20% diabetic), treated with cellulosic membranes for 8 h, 3 times a week. RESULTS: The post-dialysis body-weight decreased between the onset of HD and month 2 (M2) (-4.40+/-0.52%). Then it went up, reaching -1.56+/-0.96% at M6, +0.3+/-1.27% at M12, +1.27+/-1.38% at M18 and +1.64+/-1.33% at M24. The post-dialysis body-weight increased by 6% between M2 and M24. The mean arterial pressure (MAP) decreased from 111.3+/-2.5 mmHg at M0 to 94.4+/-1.7 at M6, and then remained stable after M6. Between M2 and M6 the post-dialysis body-weight increased, whereas the predialysis MAP continued to decline. The incidence of hypotension episodes was maximal during the first 4 months of HD treatment. CONCLUSIONS: After the second month of dialysis treatment, the simultaneous increase of post-dialysis body-weight and decrease of pre-dialysis MAP are related to the effects of two processes, i.e. increased weight as the result of anabolism induced by the HD treatment on the one hand and normalization of blood pressure by fluid removal on the other. Continuous clinical assessment of the patient is necessary to provide adequate prescription of post-dialysis body-weight. During the first months of HD treatment, the nephrologist, like Janus, is a double-faced gatekeeper: he must be willing to decrease post-dialysis weight to achieve 'dry weight' and to normalize blood pressure, but he must also be prepared to increase it to compensate for anabolism and to avoid episodes of hypotension.  (+info)

Hypotension induced by exercise is associated with enhanced release of adenyl purines from aged rat artery. (3/1770)

To determine whether the antihypertensive effects of exercise are associated with release of ATP and its metabolites from arteries, we assayed blood pressure and the release of adenine nucleotides and nucleosides from the caudal arteries of exercised and sedentary aged hypercholesterolemic rats. Exercise on a treadmill for 12 wk significantly decreased the rise in systolic and diastolic blood pressure by 7.5 and 15.9%, respectively, with advanced age. The concentrations of oleic, linoleic, and linolenic acids in the caudal artery decreased significantly with exercise, demonstrating an association between exercise and the unsaturation index of caudal arterial fatty acids. The amounts of total adenyl purines released by the arterial segments from exercised rats, both spontaneously and in response to norepinephrine, were significantly greater by 80.0 and 60.7%, respectively, than those released by tissues from sedentary rats. These results suggest that exercise alters the membrane fatty acid composition in aged rats as well as the release of ATP from vascular endothelial cells and that these factors are associated with the regression of the rise in blood pressure normally observed with advanced age.  (+info)

Mediation of humoral catecholamine secretion by the renin-angiotensin system in hypotensive rainbow trout (Oncorhynchus mykiss). (4/1770)

The individual contributions of, and potential interactions between, the renin-angiotensin system (RAS) and the humoral adrenergic stress response to blood pressure regulation were examined in rainbow trout. Intravenous injection of the smooth muscle relaxant, papaverine (10 mg/kg), elicited a transient decrease in dorsal aortic blood pressure (PDA) and systemic vascular resistance (RS), and significant increases in plasma angiotensin II (Ang II) and catecholamine concentrations. Blockade of alpha-adrenoceptors before papaverine treatment prevented PDA and RS recovery, had no effect on the increase in plasma catecholamines, and resulted in greater plasma Ang II concentrations. Administration of the angiotensin-converting enzyme inhibitor, lisinopril (10(-4) mol/kg), before papaverine treatment attenuated the increases in the plasma concentrations of Ang II, adrenaline, and noradrenaline by 90, 79, and 40%, respectively and also prevented PDA and RS recovery. By itself, lisinopril treatment caused a gradual and sustained decrease in PDA and RS, and reductions in basal plasma Ang II and adrenaline concentrations. Bolus injection of a catecholamine cocktail (4 nmol/kg noradrenaline plus 40 nmol/kg adrenaline) in the lisinopril+papaverine-treated trout, to supplement their circulating catecholamine concentrations and mimic those observed in fish treated only with papaverine, resulted in a temporary recovery in PDA and RS. These results indicate that the RAS and the acute humoral adrenergic response are both recruited during an acute hypotensive stress, and have important roles in the compensatory response to hypotension in rainbow trout. However, whereas the contribution of the RAS to PDA recovery is largely indirect and relies on an Ang II-mediated secretion of catecholamines, the contribution from the adrenergic system is direct and relies at least in part on plasma catecholamines.  (+info)

Sudden death in hypertrophic cardiomyopathy: potential importance of altered autonomic control of vasculature. (5/1770)

Current evidence suggests that alterations in the autonomic function and abnormal vascular control play a significant role either as independent triggers themselves or as modifiers of ischaemia and tolerance to to arrhythmias. A combination of several factors--that is, arrhythmia, hypotension, altered autonomic function including vascular control, and ischaemia are therefore likely to act as triggers for sudden death. The relative contribution of each of these factors needs further detailed study.  (+info)

Effects of isoflurane anesthesia on pulmonary vascular response to K+ ATP channel activation and circulatory hypotension in chronically instrumented dogs. (6/1770)

BACKGROUND: The objective of this study was to evaluate the effects of isoflurane anesthesia on the pulmonary vascular responses to exogenous adenosine triphosphate-sensitive potassium (K+ ATP) channel activation and circulatory hypotension compared with responses measured in the conscious state. In addition, the extent to which K+ ATP channel inhibition modulates the pulmonary vascular response to circulatory hypotension in conscious and isoflurane-anesthetized dogs was assessed. METHODS: Fifteen conditioned, male mongrel dogs were fitted with instruments for long-term monitoring to measure the left pulmonary vascular pressure-flow relation. The dose-response relation to the K+ ATP channel agonist, lemakalim, and the pulmonary vascular response to circulatory hypotension were assessed in conscious and isoflurane-anesthetized (approximately 1.2 minimum alveolar concentration) dogs. The effect of the selective K+ ATP channel antagonist, glibenclamide, on the pulmonary vascular response to hypotension was also assessed in conscious and isoflurane-anesthetized dogs. RESULTS: Isoflurane had no effect on the baseline pulmonary circulation, but it attenuated (P<0.05) the pulmonary vasodilator response to lemakalim. Reducing the mean systemic arterial pressure to approximately 50 mm Hg resulted in pulmonary vasoconstriction (P<0.05) in the conscious state, and this response was attenuated (P<0.05) during isoflurane. Glibenclamide had no effect on the baseline pulmonary circulation, but it potentiated (P<0.05) the pulmonary vasoconstrictor response to hypotension in conscious and isoflurane-anesthetized dogs. CONCLUSIONS: These results indicate that K+ ATP-mediated pulmonary vasodilation and the pulmonary vasoconstrictor response to hypotension are attenuated during isoflurane anesthesia. Endogenous K+ ATP channel activation modulates the pulmonary vasoconstrictor response to hypotension in the conscious state, and this effect is preserved during isoflurane anesthesia.  (+info)

Spike generation from dorsal roots and cutaneous afferents by hypoxia or hypercapnia in the rat in vivo. (7/1770)

The present study aimed at investigating the responsiveness of different parts of the primary afferent neurones to a brief hypoxia, hypercapnia or ischaemia under in vivo conditions. Action potentials were recorded in separate groups of anaesthetized rats from (i) the peripheral end of the central stump of the cut L3, L4 or L5 dorsal root (dorsal root preparation); (ii) the central end of the peripheral stump of the cut saphenous nerve (saphenous-receptor preparation); (iii) the distal end of a segment of the saphenous nerve cut at both ends (axon preparation). In paralysed animals interruption of artificial ventilation for 20-60 s elicited or increased the frequency of action potentials in both the dorsal root and saphenous-receptor preparations. Activation of these preparations was also achieved by inspiration of gas mixtures containing 10-0% oxygen (mixed with nitrogen) or 20-50% carbon dioxide (mixed with oxygen) which elicited in the blood a decrease in PO2 or an increase in PCO2 with a fall in pH. Occlusion of the femoral artery for 3 min also caused spike generation in the saphenous-receptor preparations with little alteration in blood pressure. All these stimuli failed to evoke action potentials in the axon preparations. Systemic (300 mg kg-1 s.c.) or perineural (2%) capsaicin pretreatment failed to inhibit the effect of hypoxia, hypercapnia or ischaemia, indicating a significant contribution of capsaicin-insensitive neurones to the responses. It is concluded that central and peripheral terminals but not axons of primary afferent neurones are excited by a brief hypoxia or hypercapnia and the peripheral terminals by a short local ischaemia as well. Excitation of central terminals by hypoxia or hypercapnia revealed in this way an antidromic activation of dorsal roots in response to natural chemical stimuli.  (+info)

Effects of phosphodiesterase inhibitors after coronary artery bypass grafting. (8/1770)

The aim of this study was to estimate the postoperative effects of phosphodiesterase (PDE) inhibitors (milrinone and olprinone) after coronary artery bypass grafting (CABG). To prevent hypotension caused by the PDE inhibitors, low dose of catecholamines were used concomitantly. A total of 34 elective CABG cases were tested. In 12 cases, 0.25 microg kg(-1) min(-1) of milrinone, 3 microg kg(-1) min(-1) of dobutamine (DOB) and dopamine (DOA) were used concomitantly (Group-M). In another 10 patients, 0.1 microg kg(-1) min(-1) of olprinone and the same doses of the catecholamines were infused (Group-O). As a control, the same doses of DOA and DOB only were administered in 12 patients (Group-C). When the pump flow of the cardiopulmonary bypass (CPB) decreased to half, these drugs were given in all groups. Hemodynamics were recorded before CPB, just after the operation, and 3, 6, 12, 24, 48 and 72 h after the operation. Both milrinone and olprinone increased the cardiac index and decreased systemic vascular resistance to almost the same degree. Olprinone decreased mean aortic and pulmonary artery pressures, and also significantly reduced the preload of both right and left heart compared with milrinone. Significant hypotension was not detected due to the concomitant usage of low-dose catecholamines. This concomitant usage of PDE inhibitors and catecholamines allowed easy weaning from CPB, demonstrating excellent hemodynamics after CABG. Good oxygen demand and supply balance were maintained in peripheral tissue. These results suggest that these new PDE inhibitors may be effective not only for weaning from CPB but also for post-cardiotomy cardiogenic shock.  (+info)

Hypotension is a medical term that refers to abnormally low blood pressure, usually defined as a systolic blood pressure less than 90 millimeters of mercury (mm Hg) or a diastolic blood pressure less than 60 mm Hg. Blood pressure is the force exerted by the blood against the walls of the blood vessels as the heart pumps blood.

Hypotension can cause symptoms such as dizziness, lightheadedness, weakness, and fainting, especially when standing up suddenly. In severe cases, hypotension can lead to shock, which is a life-threatening condition characterized by multiple organ failure due to inadequate blood flow.

Hypotension can be caused by various factors, including certain medications, medical conditions such as heart disease, endocrine disorders, and dehydration. It is important to seek medical attention if you experience symptoms of hypotension, as it can indicate an underlying health issue that requires treatment.

Controlled hypotension is a medical procedure in which the healthcare provider intentionally lowers the patient's blood pressure during surgery. This is done to reduce bleeding and improve surgical conditions. The goal is to maintain the patient's blood pressure at a level that is lower than their normal resting blood pressure, but high enough to ensure adequate blood flow to vital organs such as the heart and brain. Controlled hypotension is closely monitored and managed throughout the surgery to minimize risks and ensure the best possible outcomes for the patient.

Orthostatic hypotension is a type of low blood pressure that occurs when you stand up from a sitting or lying position. The drop in blood pressure causes a brief period of lightheadedness or dizziness, and can even cause fainting in some cases. This condition is also known as postural hypotension.

Orthostatic hypotension is caused by a rapid decrease in blood pressure when you stand up, which reduces the amount of blood that reaches your brain. Normally, when you stand up, your body compensates for this by increasing your heart rate and constricting blood vessels to maintain blood pressure. However, if these mechanisms fail or are impaired, orthostatic hypotension can occur.

Orthostatic hypotension is more common in older adults, but it can also affect younger people who have certain medical conditions or take certain medications. Some of the risk factors for orthostatic hypotension include dehydration, prolonged bed rest, pregnancy, diabetes, heart disease, Parkinson's disease, and certain neurological disorders.

If you experience symptoms of orthostatic hypotension, it is important to seek medical attention. Your healthcare provider can perform tests to determine the underlying cause of your symptoms and recommend appropriate treatment options. Treatment may include lifestyle changes, such as increasing fluid intake, avoiding alcohol and caffeine, and gradually changing positions from lying down or sitting to standing up. In some cases, medication may be necessary to manage orthostatic hypotension.

Intracranial hypotension is a medical condition characterized by reduced pressure within the cranial cavity (the space containing brain and cerebrospinal fluid). This can occur due to several reasons, most commonly being a spontaneous or traumatic CSF leak (cerebrospinal fluid leak) from the dural membrane that surrounds the brain and spinal cord. The decrease in CSF pressure can cause various symptoms such as headaches (often positional), nausea, vomiting, neck pain, blurred vision, ringing in the ears, and cognitive impairment. Treatment typically involves identifying and addressing the underlying cause, which may include bed rest, hydration, caffeine, epidural blood patch procedures, or surgical repair of CSF leaks.

Blood pressure is the force exerted by circulating blood on the walls of the blood vessels. It is measured in millimeters of mercury (mmHg) and is given as two figures:

1. Systolic pressure: This is the pressure when the heart pushes blood out into the arteries.
2. Diastolic pressure: This is the pressure when the heart rests between beats, allowing it to fill with blood.

Normal blood pressure for adults is typically around 120/80 mmHg, although this can vary slightly depending on age, sex, and other factors. High blood pressure (hypertension) is generally considered to be a reading of 130/80 mmHg or higher, while low blood pressure (hypotension) is usually defined as a reading below 90/60 mmHg. It's important to note that blood pressure can fluctuate throughout the day and may be affected by factors such as stress, physical activity, and medication use.

Post-exercise hypotension (PEH) is a physiological response that occurs after an exercise session, characterized by a decrease in systolic and diastolic blood pressure below pre-exercise levels. This phenomenon is typically observed within the first 15 to 60 minutes post-exercise and can last up to several hours. The magnitude of PEH varies among individuals and depends on factors such as exercise intensity, duration, and modality.

PEH has been suggested to contribute to overall cardiovascular health by promoting vasodilation, improving endothelial function, and reducing arterial stiffness. It is also considered a potential mechanism for the blood pressure-lowering effects of regular exercise training in hypertensive individuals. However, it is essential to monitor blood pressure responses during and after exercise, particularly in those with cardiovascular risk factors or established cardiovascular disease, to ensure safety and optimize health benefits.

Trimethaphan is a ganglionic blocker drug that is used primarily in the treatment of hypertensive emergencies. It works by blocking the transmission of nerve impulses at the ganglionic synapse, leading to decreased sympathetic and parasympathetic tone. This results in a decrease in peripheral vascular resistance, heart rate, and blood pressure.

Trimethaphan is administered intravenously and its effects are rapid in onset but also short-lived, typically lasting only 5-10 minutes after discontinuation of the infusion. It is therefore necessary to continuously monitor blood pressure during administration and adjust the dose as needed to maintain a stable blood pressure.

Common side effects of trimethaphan include flushing, diaphoresis, dizziness, headache, and blurred vision. More serious side effects can include bronchospasm, myocardial ischemia, and anaphylaxis. Trimethaphan should be used with caution in patients with preexisting respiratory or cardiovascular disease.

Bradycardia is a medical term that refers to an abnormally slow heart rate, typically defined as a resting heart rate of less than 60 beats per minute in adults. While some people, particularly well-trained athletes, may have a naturally low resting heart rate, bradycardia can also be a sign of an underlying health problem.

There are several potential causes of bradycardia, including:

* Damage to the heart's electrical conduction system, such as from heart disease or aging
* Certain medications, including beta blockers, calcium channel blockers, and digoxin
* Hypothyroidism (underactive thyroid gland)
* Sleep apnea
* Infection of the heart (endocarditis or myocarditis)
* Infiltrative diseases such as amyloidosis or sarcoidosis

Symptoms of bradycardia can vary depending on the severity and underlying cause. Some people with bradycardia may not experience any symptoms, while others may feel weak, fatigued, dizzy, or short of breath. In severe cases, bradycardia can lead to fainting, confusion, or even cardiac arrest.

Treatment for bradycardia depends on the underlying cause. If a medication is causing the slow heart rate, adjusting the dosage or switching to a different medication may help. In other cases, a pacemaker may be necessary to regulate the heart's rhythm. It is important to seek medical attention if you experience symptoms of bradycardia, as it can be a sign of a serious underlying condition.

Heart rate is the number of heartbeats per unit of time, often expressed as beats per minute (bpm). It can vary significantly depending on factors such as age, physical fitness, emotions, and overall health status. A resting heart rate between 60-100 bpm is generally considered normal for adults, but athletes and individuals with high levels of physical fitness may have a resting heart rate below 60 bpm due to their enhanced cardiovascular efficiency. Monitoring heart rate can provide valuable insights into an individual's health status, exercise intensity, and response to various treatments or interventions.

Ephedrine is a medication that stimulates the nervous system and is used to treat low blood pressure, asthma, and nasal congestion. It works by narrowing the blood vessels and increasing heart rate, which can help to increase blood pressure and open up the airways in the lungs. Ephedrine may also be used as a bronchodilator to treat COPD (chronic obstructive pulmonary disease).

Ephedrine is available in various forms, including tablets, capsules, and solutions for injection. It is important to follow the instructions of a healthcare provider when taking ephedrine, as it can have side effects such as rapid heart rate, anxiety, headache, and dizziness. Ephedrine should not be used by people with certain medical conditions, such as heart disease, high blood pressure, or narrow-angle glaucoma, and it should not be taken during pregnancy or breastfeeding without consulting a healthcare provider.

In addition to its medical uses, ephedrine has been used as a performance-enhancing drug and is banned by many sports organizations. It can also be found in some over-the-counter cold and allergy medications, although these products are required to carry warnings about the potential for misuse and addiction.

Spinal anesthesia is a type of regional anesthesia that involves injecting local anesthetic medication into the cerebrospinal fluid in the subarachnoid space, which is the space surrounding the spinal cord. This procedure is typically performed by introducing a needle into the lower back, between the vertebrae, to reach the subarachnoid space.

Once the local anesthetic is introduced into this space, it spreads to block nerve impulses from the corresponding levels of the spine, resulting in numbness and loss of sensation in specific areas of the body below the injection site. The extent and level of anesthesia depend on the amount and type of medication used, as well as the patient's individual response.

Spinal anesthesia is often used for surgeries involving the lower abdomen, pelvis, or lower extremities, such as cesarean sections, hernia repairs, hip replacements, and knee arthroscopies. It can also be utilized for procedures like epidural steroid injections to manage chronic pain conditions affecting the spine and lower limbs.

While spinal anesthesia provides effective pain relief during and after surgery, it may cause side effects such as low blood pressure, headache, or difficulty urinating. These potential complications should be discussed with the healthcare provider before deciding on this type of anesthesia.

Obstetrical anesthesia refers to the use of anesthetic techniques and medications during childbirth or obstetrical procedures. The goal is to provide pain relief and comfort to the birthing person while ensuring the safety of both the mother and the baby. There are different types of obstetrical anesthesia, including:

1. Local anesthesia: Injection of a local anesthetic agent to numb a specific area, such as the perineum (the area between the vagina and the anus) during childbirth.
2. Regional anesthesia: Numbing a larger region of the body using techniques like spinal or epidural anesthesia. These methods involve injecting local anesthetic agents near the spinal cord to block nerve impulses, providing pain relief in the lower half of the body.
3. General anesthesia: Using inhaled gases or intravenous medications to render the birthing person unconscious during cesarean sections (C-sections) or other surgical procedures related to childbirth.

The choice of anesthetic technique depends on various factors, including the type of delivery, the mother's medical history, and the preferences of both the mother and the healthcare team. Obstetrical anesthesia requires specialized training and expertise to ensure safe and effective pain management during labor and delivery.

Hemodynamics is the study of how blood flows through the cardiovascular system, including the heart and the vascular network. It examines various factors that affect blood flow, such as blood volume, viscosity, vessel length and diameter, and pressure differences between different parts of the circulatory system. Hemodynamics also considers the impact of various physiological and pathological conditions on these variables, and how they in turn influence the function of vital organs and systems in the body. It is a critical area of study in fields such as cardiology, anesthesiology, and critical care medicine.

The Autonomic Nervous System (ANS) is a part of the nervous system that controls involuntary actions, such as heart rate, digestion, respiratory rate, pupillary response, urination, and sexual arousal. It consists of two subdivisions: the sympathetic and parasympathetic nervous systems, which generally have opposing effects and maintain homeostasis in the body.

Autonomic Nervous System Diseases (also known as Autonomic Disorders or Autonomic Neuropathies) refer to a group of conditions that affect the functioning of the autonomic nervous system. These diseases can cause damage to the nerves that control automatic functions, leading to various symptoms and complications.

Autonomic Nervous System Diseases can be classified into two main categories:

1. Primary Autonomic Nervous System Disorders: These are conditions that primarily affect the autonomic nervous system without any underlying cause. Examples include:
* Pure Autonomic Failure (PAF): A rare disorder characterized by progressive loss of autonomic nerve function, leading to symptoms such as orthostatic hypotension, urinary retention, and constipation.
* Multiple System Atrophy (MSA): A degenerative neurological disorder that affects both the autonomic nervous system and movement coordination. Symptoms may include orthostatic hypotension, urinary incontinence, sexual dysfunction, and Parkinsonian features like stiffness and slowness of movements.
* Autonomic Neuropathy associated with Parkinson's Disease: Some individuals with Parkinson's disease develop autonomic symptoms such as orthostatic hypotension, constipation, and urinary dysfunction due to the degeneration of autonomic nerves.
2. Secondary Autonomic Nervous System Disorders: These are conditions that affect the autonomic nervous system as a result of an underlying cause or disease. Examples include:
* Diabetic Autonomic Neuropathy: A complication of diabetes mellitus that affects the autonomic nerves, leading to symptoms such as orthostatic hypotension, gastroparesis (delayed gastric emptying), and sexual dysfunction.
* Autoimmune-mediated Autonomic Neuropathies: Conditions like Guillain-Barré syndrome or autoimmune autonomic ganglionopathy can cause autonomic symptoms due to the immune system attacking the autonomic nerves.
* Infectious Autonomic Neuropathies: Certain infections, such as HIV or Lyme disease, can lead to autonomic dysfunction as a result of nerve damage.
* Toxin-induced Autonomic Neuropathy: Exposure to certain toxins, like heavy metals or organophosphate pesticides, can cause autonomic neuropathy.

Autonomic nervous system disorders can significantly impact a person's quality of life and daily functioning. Proper diagnosis and management are crucial for improving symptoms and preventing complications. Treatment options may include lifestyle modifications, medications, and in some cases, devices or surgical interventions.

In medical terms, shock is a life-threatening condition that occurs when the body is not getting enough blood flow or when the circulatory system is not functioning properly to distribute oxygen and nutrients to the tissues and organs. This results in a state of hypoxia (lack of oxygen) and cellular dysfunction, which can lead to multiple organ failure and death if left untreated.

Shock can be caused by various factors such as severe blood loss, infection, trauma, heart failure, allergic reactions, and severe burns. The symptoms of shock include low blood pressure, rapid pulse, cool and clammy skin, rapid and shallow breathing, confusion, weakness, and a bluish color to the lips and nails. Immediate medical attention is required for proper diagnosis and treatment of shock.

Anesthesia is a medical term that refers to the loss of sensation or awareness, usually induced by the administration of various drugs. It is commonly used during surgical procedures to prevent pain and discomfort. There are several types of anesthesia, including:

1. General anesthesia: This type of anesthesia causes a complete loss of consciousness and is typically used for major surgeries.
2. Regional anesthesia: This type of anesthesia numbs a specific area of the body, such as an arm or leg, while the patient remains conscious.
3. Local anesthesia: This type of anesthesia numbs a small area of the body, such as a cut or wound, and is typically used for minor procedures.

Anesthesia can be administered through various routes, including injection, inhalation, or topical application. The choice of anesthesia depends on several factors, including the type and duration of the procedure, the patient's medical history, and their overall health. Anesthesiologists are medical professionals who specialize in administering anesthesia and monitoring patients during surgical procedures to ensure their safety and comfort.

Septic shock is a serious condition that occurs as a complication of an infection that has spread throughout the body. It's characterized by a severe drop in blood pressure and abnormalities in cellular metabolism, which can lead to organ failure and death if not promptly treated.

In septic shock, the immune system overreacts to an infection, releasing an overwhelming amount of inflammatory chemicals into the bloodstream. This leads to widespread inflammation, blood vessel dilation, and leaky blood vessels, which can cause fluid to leak out of the blood vessels and into surrounding tissues. As a result, the heart may not be able to pump enough blood to vital organs, leading to organ failure.

Septic shock is often caused by bacterial infections, but it can also be caused by fungal or viral infections. It's most commonly seen in people with weakened immune systems, such as those who have recently undergone surgery, have chronic medical conditions, or are taking medications that suppress the immune system.

Prompt diagnosis and treatment of septic shock is critical to prevent long-term complications and improve outcomes. Treatment typically involves aggressive antibiotic therapy, intravenous fluids, vasopressors to maintain blood pressure, and supportive care in an intensive care unit (ICU).

Midodrine is a medication that belongs to a class of drugs called vasoconstrictors. It works by narrowing the blood vessels and increasing blood pressure. The medical definition of Midodrine is:

A synthetic derivative of the imidazole compound, adrenergic agonist, which is used in the treatment of orthostatic hypotension. Midodrine is a prodrug that is rapidly metabolized to its active form, desglymidodrine, after oral administration. It selectively binds to and activates alpha-1 adrenergic receptors, causing vasoconstriction and an increase in blood pressure. The drug's effects are most pronounced on the venous side of the circulation, leading to increased venous return and cardiac output. Midodrine is typically administered orally in divided doses throughout the day, and its use is usually reserved for patients who have not responded to other treatments for orthostatic hypotension.

Cerebrovascular circulation refers to the network of blood vessels that supply oxygenated blood and nutrients to the brain tissue, and remove waste products. It includes the internal carotid arteries, vertebral arteries, circle of Willis, and the intracranial arteries that branch off from them.

The internal carotid arteries and vertebral arteries merge to form the circle of Willis, a polygonal network of vessels located at the base of the brain. The anterior cerebral artery, middle cerebral artery, posterior cerebral artery, and communicating arteries are the major vessels that branch off from the circle of Willis and supply blood to different regions of the brain.

Interruptions or abnormalities in the cerebrovascular circulation can lead to various neurological conditions such as stroke, transient ischemic attack (TIA), and vascular dementia.

Vascular resistance is a measure of the opposition to blood flow within a vessel or a group of vessels, typically expressed in units of mmHg/(mL/min) or sometimes as dynes*sec/cm^5. It is determined by the diameter and length of the vessels, as well as the viscosity of the blood flowing through them. In general, a decrease in vessel diameter, an increase in vessel length, or an increase in blood viscosity will result in an increase in vascular resistance, while an increase in vessel diameter, a decrease in vessel length, or a decrease in blood viscosity will result in a decrease in vascular resistance. Vascular resistance is an important concept in the study of circulation and cardiovascular physiology because it plays a key role in determining blood pressure and blood flow within the body.

nitroprusside (ni-troe-rus-ide)

A rapid-acting vasodilator used in the management of severe hypertension, acute heart failure, and to reduce afterload in patients undergoing cardiac surgery. It is a potent arterial and venous dilator that decreases preload and afterload, thereby reducing myocardial oxygen demand. Nitroprusside is metabolized to cyanide, which must be monitored closely during therapy to prevent toxicity.

Pharmacologic class: Peripheral vasodilators

Therapeutic class: Antihypertensives, Vasodilators

Medical Categories: Cardiovascular Drugs, Hypertension Agents

Ocular hypotension is a medical term that refers to a condition where the pressure inside the eye (intraocular pressure or IOP) is lower than normal. The normal range for IOP is typically between 10-21 mmHg (millimeters of mercury). Ocular hypotension can occur due to various reasons, including certain medications, medical conditions, or surgical procedures that affect the eye's ability to produce or drain aqueous humor, the clear fluid inside the eye.

While mild ocular hypotension may not cause any symptoms, more significant cases can lead to complications such as decreased vision, optic nerve damage, and visual field loss. If left untreated, it could potentially result in a condition called glaucoma. It is essential to consult an eye care professional if you suspect ocular hypotension or experience any changes in your vision.

Cardiac output is a measure of the amount of blood that is pumped by the heart in one minute. It is defined as the product of stroke volume (the amount of blood pumped by the left ventricle during each contraction) and heart rate (the number of contractions per minute). Normal cardiac output at rest for an average-sized adult is about 5 to 6 liters per minute. Cardiac output can be increased during exercise or other conditions that require more blood flow, such as during illness or injury. It can be measured noninvasively using techniques such as echocardiography or invasively through a catheter placed in the heart.

Hypovolemia is a medical condition characterized by a decreased volume of circulating blood in the body, leading to inadequate tissue perfusion and oxygenation. This can occur due to various reasons such as bleeding, dehydration, vomiting, diarrhea, or excessive sweating, which result in a reduced amount of fluid in the intravascular space.

The severity of hypovolemia depends on the extent of fluid loss and can range from mild to severe. Symptoms may include thirst, dry mouth, weakness, dizziness, lightheadedness, confusion, rapid heartbeat, low blood pressure, and decreased urine output. Severe hypovolemia can lead to shock, organ failure, and even death if not treated promptly and effectively.

Ferricyanides are a class of chemical compounds that contain the ferricyanide ion (Fe(CN)6−3). The ferricyanide ion is composed of a central iron atom in the +3 oxidation state, surrounded by six cyanide ligands. Ferricyanides are strong oxidizing agents and are used in various chemical reactions, including analytical chemistry and as reagents in organic synthesis.

It's important to note that while ferricyanides themselves are not highly toxic, they can release cyanide ions if they are decomposed or reduced under certain conditions. Therefore, they should be handled with care and used in well-ventilated areas.

Syncope is a medical term defined as a transient, temporary loss of consciousness and postural tone due to reduced blood flow to the brain. It's often caused by a drop in blood pressure, which can be brought on by various factors such as dehydration, emotional stress, prolonged standing, or certain medical conditions like heart diseases, arrhythmias, or neurological disorders.

During a syncope episode, an individual may experience warning signs such as lightheadedness, dizziness, blurred vision, or nausea before losing consciousness. These episodes usually last only a few minutes and are followed by a rapid, full recovery. However, if left untreated or undiagnosed, recurrent syncope can lead to severe injuries from falls or even life-threatening conditions related to the underlying cause.

Shy-Drager syndrome (SDS) is a rare and progressive neurodegenerative disorder that affects the autonomic nervous system (ANS). The ANS controls involuntary bodily functions such as heart rate, blood pressure, sweating, digestion, and pupil dilation. SDS is also known as multiple system atrophy with orthostatic hypotension or Bradbury-Eggleston syndrome.

SDS is characterized by a combination of symptoms related to the dysfunction of the autonomic nervous system, including:

1. Orthostatic hypotension (a sudden drop in blood pressure upon standing)
2. Autonomic failure (manifesting as erectile dysfunction, urinary retention or incontinence, and gastrointestinal disturbances)
3. Parkinsonian features (tremors, rigidity, bradykinesia, and postural instability)
4. Respiratory abnormalities (breathing difficulties, especially during sleep)
5. Ocular symptoms (abnormal pupil dilation and convergence insufficiency)
6. Smooth muscle atrophy (leading to reduced bladder capacity and gastrointestinal motility issues)

The underlying cause of Shy-Drager syndrome is the degeneration of nerve cells in specific areas of the brain, particularly within the autonomic nervous system centers. The exact etiology remains unclear; however, it is believed to involve a combination of genetic and environmental factors. There is no known cure for SDS, and treatment primarily focuses on managing symptoms and improving quality of life.

Pure Autonomic Failure (PAF) is a rare neurological disorder characterized by the progressive loss of function of the autonomic nervous system, which regulates involuntary bodily functions such as heart rate, blood pressure, sweating, digestion, and bladder control. In PAF, there is no evidence of any other underlying disease or neurological condition that could explain these symptoms.

The primary feature of PAF is orthostatic hypotension, a sudden drop in blood pressure when standing up from a sitting or lying down position, which can lead to dizziness, lightheadedness, and even fainting. Other common symptoms include:

* Anhidrosis (inability to sweat) or hyperhidrosis (excessive sweating)
* Constipation or diarrhea
* Urinary incontinence or retention
* Sexual dysfunction
* Tachycardia (rapid heart rate) or bradycardia (slow heart rate)
* Difficulty regulating body temperature

The exact cause of PAF is unknown, but it is believed to be related to the degeneration of nerve cells in the autonomic nervous system. There is no cure for PAF, and treatment is focused on managing symptoms and preventing complications. This may include lifestyle changes such as increasing fluid and salt intake, wearing compression stockings, and avoiding prolonged periods of standing or sitting. Medications may also be prescribed to help regulate blood pressure, heart rate, and other autonomic functions.

A blood patch, epidural is a medical procedure used to treat a post-dural puncture headache (PDPH), which can occur after a lumbar puncture or spinal anesthesia. During the procedure, a small amount of the patient's own blood is withdrawn and injected into the epidural space, forming a clot that seals the dural tear and alleviates the headache.

The blood patch procedure involves several steps:

1. The patient is typically placed in a lateral decubitus position (lying on their side) to widen the intervertebral space.
2. The area is cleaned and prepared for the injection, similar to other sterile procedures.
3. Using a local anesthetic, the skin and underlying tissues are numbed to minimize discomfort during the procedure.
4. A thin needle is inserted into the epidural space, usually at the same level as the original dural puncture.
5. Once the needle is in the correct position, a small amount of blood (usually around 10-20 mL) is drawn from a vein in the patient's arm.
6. The withdrawn blood is then slowly injected into the epidural space through the needle.
7. After the injection, the needle is removed, and the patient is monitored for any adverse reactions or complications.

The clot formed by the injected blood helps to seal the dural tear, preventing cerebrospinal fluid (CSF) from leaking into the epidural space and causing a headache. The blood patch procedure typically provides rapid relief from PDPH, with most patients experiencing significant improvement within 30 minutes to an hour after the injection. However, in some cases, multiple blood patches may be required to achieve complete resolution of the headache.

Posture is the position or alignment of body parts supported by the muscles, especially the spine and head in relation to the vertebral column. It can be described as static (related to a stationary position) or dynamic (related to movement). Good posture involves training your body to stand, walk, sit, and lie in positions where the least strain is placed on supporting muscles and ligaments during movement or weight-bearing activities. Poor posture can lead to various health issues such as back pain, neck pain, headaches, and respiratory problems.

Intraoperative complications refer to any unforeseen problems or events that occur during the course of a surgical procedure, once it has begun and before it is completed. These complications can range from minor issues, such as bleeding or an adverse reaction to anesthesia, to major complications that can significantly impact the patient's health and prognosis.

Examples of intraoperative complications include:

1. Bleeding (hemorrhage) - This can occur due to various reasons such as injury to blood vessels or organs during surgery.
2. Infection - Surgical site infections can develop if the surgical area becomes contaminated during the procedure.
3. Anesthesia-related complications - These include adverse reactions to anesthesia, difficulty maintaining the patient's airway, or cardiovascular instability.
4. Organ injury - Accidental damage to surrounding organs can occur during surgery, leading to potential long-term consequences.
5. Equipment failure - Malfunctioning surgical equipment can lead to complications and compromise the safety of the procedure.
6. Allergic reactions - Patients may have allergies to certain medications or materials used during surgery, causing an adverse reaction.
7. Prolonged operative time - Complications may arise if a surgical procedure takes longer than expected, leading to increased risk of infection and other issues.

Intraoperative complications require prompt identification and management by the surgical team to minimize their impact on the patient's health and recovery.

A subdural effusion is an abnormal accumulation of fluid in the potential space between the dura mater (the outermost layer of the meninges that covers the brain and spinal cord) and the arachnoid membrane (one of the three layers of the meninges that surround the brain and spinal cord) in the subdural space.

Subdural effusions can occur due to various reasons, including head trauma, infection, or complications from neurosurgical procedures. The fluid accumulation may result from bleeding (subdural hematoma), inflammation, or increased cerebrospinal fluid pressure. Depending on the underlying cause and the amount of fluid accumulated, subdural effusions can cause various symptoms, such as headaches, altered mental status, or neurological deficits.

Subdural effusions are often asymptomatic and may resolve independently; however, in some cases, medical intervention might be necessary to alleviate the pressure on the brain or address the underlying condition. Imaging techniques like computed tomography (CT) or magnetic resonance imaging (MRI) scans are typically used to diagnose and monitor subdural effusions.

A tilt-table test is a diagnostic procedure used to evaluate symptoms of syncope (fainting) or near-syncope. It measures your body's cardiovascular response to changes in position. During the test, you lie on a table that can be tilted to change the angle of your body from horizontal to upright. This simulates what happens when you stand up from a lying down position.

The test monitors heart rate, blood pressure, and oxygen levels while you're in different positions. If you experience symptoms like dizziness or fainting during the test, these can provide clues about the cause of your symptoms. The test is used to diagnose conditions like orthostatic hypotension (a sudden drop in blood pressure when standing), vasovagal syncope (fainting due to an overactive vagus nerve), and other heart rhythm disorders.

Intracranial pressure (ICP) is the pressure inside the skull and is typically measured in millimeters of mercury (mmHg). It's the measurement of the pressure exerted by the cerebrospinal fluid (CSF), blood, and brain tissue within the confined space of the skull.

Normal ICP ranges from 5 to 15 mmHg in adults when lying down. Intracranial pressure may increase due to various reasons such as bleeding in the brain, swelling of the brain, increased production or decreased absorption of CSF, and brain tumors. Elevated ICP is a serious medical emergency that can lead to brain damage or even death if not promptly treated. Symptoms of high ICP may include severe headache, vomiting, altered consciousness, and visual changes.

Vasoconstrictor agents are substances that cause the narrowing of blood vessels by constricting the smooth muscle in their walls. This leads to an increase in blood pressure and a decrease in blood flow. They work by activating the sympathetic nervous system, which triggers the release of neurotransmitters such as norepinephrine and epinephrine that bind to alpha-adrenergic receptors on the smooth muscle cells of the blood vessel walls, causing them to contract.

Vasoconstrictor agents are used medically for a variety of purposes, including:

* Treating hypotension (low blood pressure)
* Controlling bleeding during surgery or childbirth
* Relieving symptoms of nasal congestion in conditions such as the common cold or allergies

Examples of vasoconstrictor agents include phenylephrine, oxymetazoline, and epinephrine. It's important to note that prolonged use or excessive doses of vasoconstrictor agents can lead to rebound congestion and other adverse effects, so they should be used with caution and under the guidance of a healthcare professional.

Hemorrhagic shock is a type of shock that occurs when there is significant blood loss leading to inadequate perfusion of tissues and organs. It is characterized by hypovolemia (low blood volume), hypotension (low blood pressure), tachycardia (rapid heart rate), and decreased urine output. Hemorrhagic shock can be classified into four stages based on the amount of blood loss and hemodynamic changes. In severe cases, it can lead to multi-organ dysfunction and death if not treated promptly and effectively.

The cardiovascular system, also known as the circulatory system, is a biological system responsible for pumping and transporting blood throughout the body in animals and humans. It consists of the heart, blood vessels (comprising arteries, veins, and capillaries), and blood. The main function of this system is to transport oxygen, nutrients, hormones, and cellular waste products throughout the body to maintain homeostasis and support organ function.

The heart acts as a muscular pump that contracts and relaxes to circulate blood. It has four chambers: two atria on the top and two ventricles on the bottom. The right side of the heart receives deoxygenated blood from the body, pumps it through the lungs for oxygenation, and then sends it back to the left side of the heart. The left side of the heart then pumps the oxygenated blood through the aorta and into the systemic circulation, reaching all parts of the body via a network of arteries and capillaries. Deoxygenated blood is collected by veins and returned to the right atrium, completing the cycle.

The cardiovascular system plays a crucial role in regulating temperature, pH balance, and fluid balance throughout the body. It also contributes to the immune response and wound healing processes. Dysfunctions or diseases of the cardiovascular system can lead to severe health complications, such as hypertension, coronary artery disease, heart failure, stroke, and peripheral artery disease.

Fluid therapy, in a medical context, refers to the administration of fluids into a patient's circulatory system for various therapeutic purposes. This can be done intravenously (through a vein), intraosseously (through a bone), or subcutaneously (under the skin). The goal of fluid therapy is to correct or prevent imbalances in the body's fluids and electrolytes, maintain or restore blood volume, and support organ function.

The types of fluids used in fluid therapy can include crystalloids (which contain electrolytes and water) and colloids (which contain larger molecules like proteins). The choice of fluid depends on the patient's specific needs and condition. Fluid therapy is commonly used in the treatment of dehydration, shock, sepsis, trauma, surgery, and other medical conditions that can affect the body's fluid balance.

Proper administration of fluid therapy requires careful monitoring of the patient's vital signs, urine output, electrolyte levels, and overall clinical status to ensure that the therapy is effective and safe.

Hemorrhage is defined in the medical context as an excessive loss of blood from the circulatory system, which can occur due to various reasons such as injury, surgery, or underlying health conditions that affect blood clotting or the integrity of blood vessels. The bleeding may be internal, external, visible, or concealed, and it can vary in severity from minor to life-threatening, depending on the location and extent of the bleeding. Hemorrhage is a serious medical emergency that requires immediate attention and treatment to prevent further blood loss, organ damage, and potential death.

The sympathetic nervous system (SNS) is a part of the autonomic nervous system that operates largely below the level of consciousness, and it functions to produce appropriate physiological responses to perceived danger. It's often associated with the "fight or flight" response. The SNS uses nerve impulses to stimulate target organs, causing them to speed up (e.g., increased heart rate), prepare for action, or otherwise respond to stressful situations.

The sympathetic nervous system is activated due to stressful emotional or physical situations and it prepares the body for immediate actions. It dilates the pupils, increases heart rate and blood pressure, accelerates breathing, and slows down digestion. The primary neurotransmitter involved in this system is norepinephrine (also known as noradrenaline).

I believe there might be a misunderstanding in your question. "Dogs" is not a medical term or condition. It is the common name for a domesticated carnivore of the family Canidae, specifically the genus Canis, which includes wolves, foxes, and other extant and extinct species of mammals. Dogs are often kept as pets and companions, and they have been bred in a wide variety of forms and sizes for different purposes, such as hunting, herding, guarding, assisting police and military forces, and providing companionship and emotional support.

If you meant to ask about a specific medical condition or term related to dogs, please provide more context so I can give you an accurate answer.

Blood volume refers to the total amount of blood present in an individual's circulatory system at any given time. It is the combined volume of both the plasma (the liquid component of blood) and the formed elements (such as red and white blood cells and platelets) in the blood. In a healthy adult human, the average blood volume is approximately 5 liters (or about 1 gallon). However, blood volume can vary depending on several factors, including age, sex, body weight, and overall health status.

Blood volume plays a critical role in maintaining proper cardiovascular function, as it affects blood pressure, heart rate, and the delivery of oxygen and nutrients to tissues throughout the body. Changes in blood volume can have significant impacts on an individual's health and may be associated with various medical conditions, such as dehydration, hemorrhage, heart failure, and liver disease. Accurate measurement of blood volume is essential for diagnosing and managing these conditions, as well as for guiding treatment decisions in clinical settings.

A Cesarean section, often referred to as a C-section, is a surgical procedure used to deliver a baby. It involves making an incision through the mother's abdomen and uterus to remove the baby. This procedure may be necessary when a vaginal delivery would put the mother or the baby at risk.

There are several reasons why a C-section might be recommended, including:

* The baby is in a breech position (feet first) or a transverse position (sideways) and cannot be turned to a normal head-down position.
* The baby is too large to safely pass through the mother's birth canal.
* The mother has a medical condition, such as heart disease or high blood pressure, that could make vaginal delivery risky.
* The mother has an infection, such as HIV or herpes, that could be passed to the baby during a vaginal delivery.
* The labor is not progressing and there are concerns about the health of the mother or the baby.

C-sections are generally safe for both the mother and the baby, but like any surgery, they do carry some risks. These can include infection, bleeding, blood clots, and injury to nearby organs. In addition, women who have a C-section are more likely to experience complications in future pregnancies, such as placenta previa or uterine rupture.

If you have questions about whether a C-section is necessary for your delivery, it's important to discuss your options with your healthcare provider.

Methyldopa is a centrally acting antihypertensive drug, which means it works in the brain to lower blood pressure. It is a synthetic derivative of the amino acid L-DOPA and acts as a false neurotransmitter, mimicking the action of norepinephrine in the brain. This results in decreased sympathetic outflow from the central nervous system, leading to vasodilation and reduced blood pressure. Methyldopa is used primarily for the treatment of hypertension (high blood pressure) and is available in oral formulations.

Epidural anesthesia is a type of regional anesthesia that involves the injection of local anesthetic medication into the epidural space in the spine, which is the space surrounding the dura mater, a membrane that covers the spinal cord. The injection is typically administered through a catheter placed in the lower back using a needle.

The local anesthetic drug blocks nerve impulses from the affected area, numbing it and relieving pain. Epidural anesthesia can be used for various surgical procedures, such as cesarean sections, knee or hip replacements, and hernia repairs. It is also commonly used during childbirth to provide pain relief during labor and delivery.

The effects of epidural anesthesia can vary depending on the dose and type of medication used, as well as the individual's response to the drug. The anesthetic may take several minutes to start working, and its duration of action can range from a few hours to a day or more. Epidural anesthesia is generally considered safe when administered by trained medical professionals, but like any medical procedure, it carries some risks, including infection, bleeding, nerve damage, and respiratory depression.

The Autonomic Nervous System (ANS) is a part of the peripheral nervous system that operates largely below the level of consciousness and controls visceral functions. It is divided into two main subdivisions: the sympathetic and parasympathetic nervous systems, which generally have opposing effects and maintain homeostasis in the body.

The Sympathetic Nervous System (SNS) prepares the body for stressful or emergency situations, often referred to as the "fight or flight" response. It increases heart rate, blood pressure, respiratory rate, and metabolic rate, while also decreasing digestive activity. This response helps the body respond quickly to perceived threats.

The Parasympathetic Nervous System (PNS), on the other hand, promotes the "rest and digest" state, allowing the body to conserve energy and restore itself after the stress response has subsided. It decreases heart rate, blood pressure, and respiratory rate, while increasing digestive activity and promoting relaxation.

These two systems work together to maintain balance in the body by adjusting various functions based on internal and external demands. Disorders of the Autonomic Nervous System can lead to a variety of symptoms, such as orthostatic hypotension, gastroparesis, and cardiac arrhythmias, among others.

Bionics is the application of biological methods and systems found in nature to the design of engineering systems and technologies. It involves the study of biological systems, such as sensory organs or locomotion, and then using that knowledge to create artificial systems that mimic those natural processes. In other words, bionics seeks to combine biology and technology to create innovative solutions to various challenges.

In a medical context, bionics often refers to the use of artificial devices or implants that are designed to function in a similar way to biological structures or functions. For example, cochlear implants are a type of bionic device that can help restore hearing in people with severe hearing loss by converting sound into electrical signals that stimulate the auditory nerve. Similarly, bionic limbs use sensors and motors to mimic the natural movement of human limbs, allowing amputees to regain some degree of mobility and independence.

Overall, bionics represents a fascinating intersection between biology and technology, with the potential to improve the quality of life for many people around the world.

Isotonic solutions are defined in the context of medical and physiological sciences as solutions that contain the same concentration of solutes (dissolved particles) as another solution, usually the bodily fluids like blood. This means that if you compare the concentration of solute particles in two isotonic solutions, they will be equal.

A common example is a 0.9% sodium chloride (NaCl) solution, also known as normal saline. The concentration of NaCl in this solution is approximately equal to the concentration found in the fluid portion of human blood, making it isotonic with blood.

Isotonic solutions are crucial in medical settings for various purposes, such as intravenous (IV) fluids replacement, wound care, and irrigation solutions. They help maintain fluid balance, prevent excessive water movement across cell membranes, and reduce the risk of damaging cells due to osmotic pressure differences between the solution and bodily fluids.

Pressoreceptors are specialized sensory nerve endings found in the walls of blood vessels, particularly in the carotid sinus and aortic arch. They respond to changes in blood pressure by converting the mechanical stimulus into electrical signals that are transmitted to the brain. This information helps regulate cardiovascular function and maintain blood pressure homeostasis.

Phenylephrine is a medication that belongs to the class of drugs known as sympathomimetic amines. It primarily acts as an alpha-1 adrenergic receptor agonist, which means it stimulates these receptors, leading to vasoconstriction (constriction of blood vessels). This effect can be useful in various medical situations, such as:

1. Nasal decongestion: When applied topically in the nose, phenylephrine causes constriction of the blood vessels in the nasal passages, which helps to relieve congestion and swelling. It is often found in over-the-counter (OTC) cold and allergy products.
2. Ocular circulation: In ophthalmology, phenylephrine is used to dilate the pupils before eye examinations. The increased pressure from vasoconstriction helps to open up the pupil, allowing for a better view of the internal structures of the eye.
3. Hypotension management: In some cases, phenylephrine may be given intravenously to treat low blood pressure (hypotension) during medical procedures like spinal anesthesia or septic shock. The vasoconstriction helps to increase blood pressure and improve perfusion of vital organs.

It is essential to use phenylephrine as directed, as improper usage can lead to adverse effects such as increased heart rate, hypertension, arrhythmias, and rebound congestion (when used as a nasal decongestant). Always consult with a healthcare professional for appropriate guidance on using this medication.

Norepinephrine, also known as noradrenaline, is a neurotransmitter and a hormone that is primarily produced in the adrenal glands and is released into the bloodstream in response to stress or physical activity. It plays a crucial role in the "fight-or-flight" response by preparing the body for action through increasing heart rate, blood pressure, respiratory rate, and glucose availability.

As a neurotransmitter, norepinephrine is involved in regulating various functions of the nervous system, including attention, perception, motivation, and arousal. It also plays a role in modulating pain perception and responding to stressful or emotional situations.

In medical settings, norepinephrine is used as a vasopressor medication to treat hypotension (low blood pressure) that can occur during septic shock, anesthesia, or other critical illnesses. It works by constricting blood vessels and increasing heart rate, which helps to improve blood pressure and perfusion of vital organs.

Regional blood flow (RBF) refers to the rate at which blood flows through a specific region or organ in the body, typically expressed in milliliters per minute per 100 grams of tissue (ml/min/100g). It is an essential physiological parameter that reflects the delivery of oxygen and nutrients to tissues while removing waste products. RBF can be affected by various factors such as metabolic demands, neural regulation, hormonal influences, and changes in blood pressure or vascular resistance. Measuring RBF is crucial for understanding organ function, diagnosing diseases, and evaluating the effectiveness of treatments.

In the field of medicine, "time factors" refer to the duration of symptoms or time elapsed since the onset of a medical condition, which can have significant implications for diagnosis and treatment. Understanding time factors is crucial in determining the progression of a disease, evaluating the effectiveness of treatments, and making critical decisions regarding patient care.

For example, in stroke management, "time is brain," meaning that rapid intervention within a specific time frame (usually within 4.5 hours) is essential to administering tissue plasminogen activator (tPA), a clot-busting drug that can minimize brain damage and improve patient outcomes. Similarly, in trauma care, the "golden hour" concept emphasizes the importance of providing definitive care within the first 60 minutes after injury to increase survival rates and reduce morbidity.

Time factors also play a role in monitoring the progression of chronic conditions like diabetes or heart disease, where regular follow-ups and assessments help determine appropriate treatment adjustments and prevent complications. In infectious diseases, time factors are crucial for initiating antibiotic therapy and identifying potential outbreaks to control their spread.

Overall, "time factors" encompass the significance of recognizing and acting promptly in various medical scenarios to optimize patient outcomes and provide effective care.

The baroreflex is a physiological mechanism that helps regulate blood pressure and heart rate in response to changes in stretch of the arterial walls. It is mediated by baroreceptors, which are specialized sensory nerve endings located in the carotid sinus and aortic arch. These receptors detect changes in blood pressure and send signals to the brainstem via the glossopharyngeal (cranial nerve IX) and vagus nerves (cranial nerve X), respectively.

In response to an increase in arterial pressure, the baroreceptors are stimulated, leading to increased firing of afferent neurons that signal the brainstem. This results in a reflexive decrease in heart rate and cardiac output, as well as vasodilation of peripheral blood vessels, which collectively work to reduce blood pressure back towards its normal level. Conversely, if arterial pressure decreases, the baroreceptors are less stimulated, leading to an increase in heart rate and cardiac output, as well as vasoconstriction of peripheral blood vessels, which helps restore blood pressure.

Overall, the baroreflex is a crucial homeostatic mechanism that helps maintain stable blood pressure and ensure adequate perfusion of vital organs.

Antihypertensive agents are a class of medications used to treat high blood pressure (hypertension). They work by reducing the force and rate of heart contractions, dilating blood vessels, or altering neurohormonal activation to lower blood pressure. Examples include diuretics, beta blockers, ACE inhibitors, ARBs, calcium channel blockers, and direct vasodilators. These medications may be used alone or in combination to achieve optimal blood pressure control.

Splanchnic circulation refers to the blood flow to the visceral organs, including the gastrointestinal tract, pancreas, spleen, and liver. These organs receive a significant portion of the cardiac output, with approximately 25-30% of the total restingly going to the splanchnic circulation. The splanchnic circulation is regulated by a complex interplay of neural and hormonal mechanisms that help maintain adequate blood flow to these vital organs while also allowing for the distribution of blood to other parts of the body as needed.

The splanchnic circulation is unique in its ability to vasodilate and increase blood flow significantly in response to meals or other stimuli, such as stress or hormonal changes. This increased blood flow helps support the digestive process and absorption of nutrients. At the same time, the body must carefully regulate this blood flow to prevent a significant drop in blood pressure or overloading the heart with too much work.

Overall, the splanchnic circulation plays a critical role in maintaining the health and function of the body's vital organs, and dysregulation of this system can contribute to various diseases, including digestive disorders, liver disease, and cardiovascular disease.

Clonidine is an medication that belongs to a class of drugs called centrally acting alpha-agonist hypotensives. It works by stimulating certain receptors in the brain and lowering the heart rate, which results in decreased blood pressure. Clonidine is commonly used to treat hypertension (high blood pressure), but it can also be used for other purposes such as managing withdrawal symptoms from opioids or alcohol, treating attention deficit hyperactivity disorder (ADHD), and preventing migraines. It can be taken orally in the form of tablets or transdermally through a patch applied to the skin. As with any medication, clonidine should be used under the guidance and supervision of a healthcare provider.

Vasodilation is the widening or increase in diameter of blood vessels, particularly the involuntary relaxation of the smooth muscle in the tunica media (middle layer) of the arteriole walls. This results in an increase in blood flow and a decrease in vascular resistance. Vasodilation can occur due to various physiological and pathophysiological stimuli, such as local metabolic demands, neural signals, or pharmacological agents. It plays a crucial role in regulating blood pressure, tissue perfusion, and thermoregulation.

Lypressin is a synthetic analogue of a natural hormone called vasopressin, which is produced by the pituitary gland in the brain. The primary function of vasopressin, also known as antidiuretic hormone (ADH), is to regulate water balance in the body by controlling the amount of urine produced by the kidneys.

Lypressin has similar physiological effects to vasopressin and is used in medical treatments for conditions related to the regulation of water balance, such as diabetes insipidus. Diabetes insipidus is a condition characterized by excessive thirst and the production of large amounts of dilute urine due to a deficiency in vasopressin or an impaired response to it.

In summary, Lypressin is a synthetic form of vasopressin, a hormone that helps regulate water balance in the body by controlling urine production in the kidneys. It is used as a therapeutic agent for treating diabetes insipidus and related conditions.

A dose-response relationship in the context of drugs refers to the changes in the effects or symptoms that occur as the dose of a drug is increased or decreased. Generally, as the dose of a drug is increased, the severity or intensity of its effects also increases. Conversely, as the dose is decreased, the effects of the drug become less severe or may disappear altogether.

The dose-response relationship is an important concept in pharmacology and toxicology because it helps to establish the safe and effective dosage range for a drug. By understanding how changes in the dose of a drug affect its therapeutic and adverse effects, healthcare providers can optimize treatment plans for their patients while minimizing the risk of harm.

The dose-response relationship is typically depicted as a curve that shows the relationship between the dose of a drug and its effect. The shape of the curve may vary depending on the drug and the specific effect being measured. Some drugs may have a steep dose-response curve, meaning that small changes in the dose can result in large differences in the effect. Other drugs may have a more gradual dose-response curve, where larger changes in the dose are needed to produce significant effects.

In addition to helping establish safe and effective dosages, the dose-response relationship is also used to evaluate the potential therapeutic benefits and risks of new drugs during clinical trials. By systematically testing different doses of a drug in controlled studies, researchers can identify the optimal dosage range for the drug and assess its safety and efficacy.

Plasma substitutes are fluids that are used to replace the plasma volume in conditions such as hypovolemia (low blood volume) or plasma loss, for example due to severe burns, trauma, or major surgery. They do not contain cells or clotting factors, but they help to maintain intravascular volume and tissue perfusion. Plasma substitutes can be divided into two main categories: crystalloids and colloids.

Crystalloid solutions contain small molecules that can easily move between intracellular and extracellular spaces. Examples include normal saline (0.9% sodium chloride) and lactated Ringer's solution. They are less expensive and have a lower risk of allergic reactions compared to colloids, but they may require larger volumes to achieve the same effect due to their rapid distribution in the body.

Colloid solutions contain larger molecules that tend to stay within the intravascular space for longer periods, thus increasing the oncotic pressure and helping to maintain fluid balance. Examples include albumin, fresh frozen plasma, and synthetic colloids such as hydroxyethyl starch (HES) and gelatin. Colloids may be more effective in restoring intravascular volume, but they carry a higher risk of allergic reactions and anaphylaxis, and some types have been associated with adverse effects such as kidney injury and coagulopathy.

The choice of plasma substitute depends on various factors, including the patient's clinical condition, the underlying cause of plasma loss, and any contraindications or potential side effects of the available products. It is important to monitor the patient's hemodynamic status, electrolyte balance, and coagulation profile during and after the administration of plasma substitutes to ensure appropriate resuscitation and avoid complications.

Vasovagal syncope is a type of fainting (syncope) that occurs when the body overreacts to certain triggers, such as the sight of blood or extreme emotional distress. This reaction causes the heart rate and blood pressure to drop, leading to reduced blood flow to the brain and loss of consciousness. Vasovagal syncope is usually not a cause for concern and does not typically indicate a serious underlying medical condition. However, it can be dangerous if it occurs during activities such as driving or operating heavy machinery. If you experience frequent episodes of vasovagal syncope, it is important to speak with a healthcare provider for evaluation and treatment options.

Intravenous (IV) infusion is a medical procedure in which liquids, such as medications, nutrients, or fluids, are delivered directly into a patient's vein through a needle or a catheter. This route of administration allows for rapid absorption and distribution of the infused substance throughout the body. IV infusions can be used for various purposes, including resuscitation, hydration, nutrition support, medication delivery, and blood product transfusion. The rate and volume of the infusion are carefully controlled to ensure patient safety and efficacy of treatment.

Sprague-Dawley rats are a strain of albino laboratory rats that are widely used in scientific research. They were first developed by researchers H.H. Sprague and R.C. Dawley in the early 20th century, and have since become one of the most commonly used rat strains in biomedical research due to their relatively large size, ease of handling, and consistent genetic background.

Sprague-Dawley rats are outbred, which means that they are genetically diverse and do not suffer from the same limitations as inbred strains, which can have reduced fertility and increased susceptibility to certain diseases. They are also characterized by their docile nature and low levels of aggression, making them easier to handle and study than some other rat strains.

These rats are used in a wide variety of research areas, including toxicology, pharmacology, nutrition, cancer, and behavioral studies. Because they are genetically diverse, Sprague-Dawley rats can be used to model a range of human diseases and conditions, making them an important tool in the development of new drugs and therapies.

Fludrocortisone is a synthetic corticosteroid hormone, specifically a mineralocorticoid. It is often used to treat conditions associated with low levels of corticosteroids, such as Addison's disease. It works by helping the body retain sodium and lose potassium, which helps to maintain fluid balance and blood pressure.

In medical terms, fludrocortisone is defined as a synthetic mineralocorticoid with glucocorticoid activity used in the treatment of adrenogenital syndrome and Addison's disease, and as an adjunct in the treatment of rheumatoid arthritis. It is also used to treat orthostatic hypotension by helping the body retain sodium and water, thereby increasing blood volume and blood pressure.

It is important to note that fludrocortisone can have significant side effects, particularly if used in high doses or for long periods of time. These can include fluid retention, high blood pressure, increased risk of infection, and slowed growth in children. As with any medication, it should be used under the close supervision of a healthcare provider.

The Valsalva maneuver is a medical procedure that involves forced exhalation against a closed airway, typically by closing one's mouth, pinching the nose shut, and then blowing. This maneuver increases the pressure in the chest and affects the heart's filling and pumping capabilities, as well as the pressures within the ears and eyes.

It is often used during medical examinations to test for conditions such as heart murmurs or to help clear the ears during changes in air pressure (like when scuba diving or flying). It can also be used to help diagnose or monitor conditions related to the autonomic nervous system, such as orthostatic hypotension or dysautonomia.

However, it's important to perform the Valsalva maneuver correctly and under medical supervision, as improper technique or overdoing it can lead to adverse effects like increased heart rate, changes in blood pressure, or even damage to the eardrum.

Renal dialysis is a medical procedure that is used to artificially remove waste products, toxins, and excess fluids from the blood when the kidneys are no longer able to perform these functions effectively. This process is also known as hemodialysis.

During renal dialysis, the patient's blood is circulated through a special machine called a dialyzer or an artificial kidney, which contains a semi-permeable membrane that filters out waste products and excess fluids from the blood. The cleaned blood is then returned to the patient's body.

Renal dialysis is typically recommended for patients with advanced kidney disease or kidney failure, such as those with end-stage renal disease (ESRD). It is a life-sustaining treatment that helps to maintain the balance of fluids and electrolytes in the body, prevent the buildup of waste products and toxins, and control blood pressure.

There are two main types of renal dialysis: hemodialysis and peritoneal dialysis. Hemodialysis is the most common type and involves using a dialyzer to filter the blood outside the body. Peritoneal dialysis, on the other hand, involves placing a catheter in the abdomen and using the lining of the abdomen (peritoneum) as a natural filter to remove waste products and excess fluids from the body.

Overall, renal dialysis is an essential treatment option for patients with kidney failure, helping them to maintain their quality of life and prolong their survival.

Hydralazine is an antihypertensive medication, which means it is used to treat high blood pressure. It works by relaxing and widening the blood vessels, making it easier for the heart to pump blood through the body. This can help reduce the workload on the heart and lower blood pressure. Hydralazine is available in oral tablet form and is typically prescribed to be taken several times a day.

Hydralazine belongs to a class of medications called vasodilators, which work by relaxing the muscle in the walls of the blood vessels, causing them to widen. This increases the amount of blood that can flow through the blood vessels and reduces the pressure within them. Hydralazine is often used in combination with other medications to treat high blood pressure.

It's important to note that hydralazine should be used under the close supervision of a healthcare provider, as it can cause side effects such as headache, dizziness, and rapid heartbeat. It may also interact with certain other medications, so it is important to inform your doctor of all medications you are taking before starting hydralazine.

Isoflurane is a volatile halogenated ether used for induction and maintenance of general anesthesia. It is a colorless liquid with a pungent, sweet odor. Isoflurane is an agonist at the gamma-aminobutyric acid type A (GABAA) receptor and inhibits excitatory neurotransmission in the brain, leading to unconsciousness and immobility. It has a rapid onset and offset of action due to its low blood solubility, allowing for quick adjustments in anesthetic depth during surgery. Isoflurane is also known for its bronchodilator effects, making it useful in patients with reactive airway disease. However, it can cause dose-dependent decreases in heart rate and blood pressure, so careful hemodynamic monitoring is required during its use.

Intravenous injections are a type of medical procedure where medication or fluids are administered directly into a vein using a needle and syringe. This route of administration is also known as an IV injection. The solution injected enters the patient's bloodstream immediately, allowing for rapid absorption and onset of action. Intravenous injections are commonly used to provide quick relief from symptoms, deliver medications that are not easily absorbed by other routes, or administer fluids and electrolytes in cases of dehydration or severe illness. It is important that intravenous injections are performed using aseptic technique to minimize the risk of infection.

Bupivacaine is a long-acting local anesthetic drug, which is used to cause numbness or loss of feeling in a specific area of the body during certain medical procedures such as surgery, dental work, or childbirth. It works by blocking the nerves that transmit pain signals to the brain.

Bupivacaine is available as a solution for injection and is usually administered directly into the tissue surrounding the nerve to be blocked (nerve block) or into the spinal fluid (epidural). The onset of action of bupivacaine is relatively slow, but its duration of action is long, making it suitable for procedures that require prolonged pain relief.

Like all local anesthetics, bupivacaine carries a risk of side effects such as allergic reactions, nerve damage, and systemic toxicity if accidentally injected into a blood vessel or given in excessive doses. It should be used with caution in patients with certain medical conditions, including heart disease, liver disease, and neurological disorders.

A reflex is an automatic, involuntary and rapid response to a stimulus that occurs without conscious intention. In the context of physiology and neurology, it's a basic mechanism that involves the transmission of nerve impulses between neurons, resulting in a muscle contraction or glandular secretion.

Reflexes are important for maintaining homeostasis, protecting the body from harm, and coordinating movements. They can be tested clinically to assess the integrity of the nervous system, such as the knee-j jerk reflex, which tests the function of the L3-L4 spinal nerve roots and the sensitivity of the stretch reflex arc.

The supine position is a term used in medicine to describe a body posture where an individual is lying down on their back, with their face and torso facing upwards. This position is often adopted during various medical procedures, examinations, or when resting, as it allows for easy access to the front of the body. It is also the position automatically assumed by most people who are falling asleep.

It's important to note that in the supine position, the head can be flat on the surface or raised with the use of pillows or specialized medical equipment like a hospital bed. This can help to alleviate potential issues such as breathing difficulties or swelling in the face and head.

Prospective studies, also known as longitudinal studies, are a type of cohort study in which data is collected forward in time, following a group of individuals who share a common characteristic or exposure over a period of time. The researchers clearly define the study population and exposure of interest at the beginning of the study and follow up with the participants to determine the outcomes that develop over time. This type of study design allows for the investigation of causal relationships between exposures and outcomes, as well as the identification of risk factors and the estimation of disease incidence rates. Prospective studies are particularly useful in epidemiology and medical research when studying diseases with long latency periods or rare outcomes.

General anesthesia is a state of controlled unconsciousness, induced by administering various medications, that eliminates awareness, movement, and pain sensation during medical procedures. It involves the use of a combination of intravenous and inhaled drugs to produce a reversible loss of consciousness, allowing patients to undergo surgical or diagnostic interventions safely and comfortably. The depth and duration of anesthesia are carefully monitored and adjusted throughout the procedure by an anesthesiologist or certified registered nurse anesthetist (CRNA) to ensure patient safety and optimize recovery. General anesthesia is typically used for more extensive surgical procedures, such as open-heart surgery, major orthopedic surgeries, and neurosurgery.

Hypertension is a medical term used to describe abnormally high blood pressure in the arteries, often defined as consistently having systolic blood pressure (the top number in a blood pressure reading) over 130 mmHg and/or diastolic blood pressure (the bottom number) over 80 mmHg. It is also commonly referred to as high blood pressure.

Hypertension can be classified into two types: primary or essential hypertension, which has no identifiable cause and accounts for about 95% of cases, and secondary hypertension, which is caused by underlying medical conditions such as kidney disease, hormonal disorders, or use of certain medications.

If left untreated, hypertension can lead to serious health complications such as heart attack, stroke, heart failure, and chronic kidney disease. Therefore, it is important for individuals with hypertension to manage their condition through lifestyle modifications (such as healthy diet, regular exercise, stress management) and medication if necessary, under the guidance of a healthcare professional.

Vasodilator agents are pharmacological substances that cause the relaxation or widening of blood vessels by relaxing the smooth muscle in the vessel walls. This results in an increase in the diameter of the blood vessels, which decreases vascular resistance and ultimately reduces blood pressure. Vasodilators can be further classified based on their site of action:

1. Systemic vasodilators: These agents cause a generalized relaxation of the smooth muscle in the walls of both arteries and veins, resulting in a decrease in peripheral vascular resistance and preload (the volume of blood returning to the heart). Examples include nitroglycerin, hydralazine, and calcium channel blockers.
2. Arterial vasodilators: These agents primarily affect the smooth muscle in arterial vessel walls, leading to a reduction in afterload (the pressure against which the heart pumps blood). Examples include angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), and direct vasodilators like sodium nitroprusside.
3. Venous vasodilators: These agents primarily affect the smooth muscle in venous vessel walls, increasing venous capacitance and reducing preload. Examples include nitroglycerin and other organic nitrates.

Vasodilator agents are used to treat various cardiovascular conditions such as hypertension, heart failure, angina, and pulmonary arterial hypertension. It is essential to monitor their use carefully, as excessive vasodilation can lead to orthostatic hypotension, reflex tachycardia, or fluid retention.

Heat stroke is a serious and potentially life-threatening condition that occurs when the body becomes unable to regulate its temperature. It is characterized by a core body temperature of 104°F (40°C) or higher, and symptoms such as hot, dry skin or heavy sweating; confusion or loss of consciousness; rapid pulse; rapid breathing; and seizures or convulsions. Heat stroke can be caused by prolonged exposure to high temperatures, physical exertion in hot weather, or dehydration. It is a medical emergency that requires immediate treatment to prevent serious complications, such as organ damage or failure, and it can be fatal if not treated promptly.

Anaphylaxis is a severe, life-threatening systemic allergic reaction that occurs suddenly after exposure to an allergen (a substance that triggers an allergic reaction) to which the person has previously been sensitized. The symptoms of anaphylaxis include rapid onset of symptoms such as itching, hives, swelling of the throat and tongue, difficulty breathing, wheezing, cough, chest tightness, rapid heartbeat, hypotension (low blood pressure), shock, and in severe cases, loss of consciousness and death. Anaphylaxis is a medical emergency that requires immediate treatment with epinephrine (adrenaline) and other supportive measures to stabilize the patient's condition.

Tachycardia is a medical term that refers to an abnormally rapid heart rate, often defined as a heart rate greater than 100 beats per minute in adults. It can occur in either the atria (upper chambers) or ventricles (lower chambers) of the heart. Different types of tachycardia include supraventricular tachycardia (SVT), atrial fibrillation, atrial flutter, and ventricular tachycardia.

Tachycardia can cause various symptoms such as palpitations, shortness of breath, dizziness, lightheadedness, chest discomfort, or syncope (fainting). In some cases, tachycardia may not cause any symptoms and may only be detected during a routine physical examination or medical test.

The underlying causes of tachycardia can vary widely, including heart disease, electrolyte imbalances, medications, illicit drug use, alcohol abuse, smoking, stress, anxiety, and other medical conditions. In some cases, the cause may be unknown. Treatment for tachycardia depends on the underlying cause, type, severity, and duration of the arrhythmia.

Intraoperative monitoring (IOM) is the practice of using specialized techniques to monitor physiological functions or neural structures in real-time during surgical procedures. The primary goal of IOM is to provide continuous information about the patient's status and the effects of surgery on neurological function, allowing surgeons to make informed decisions and minimize potential risks.

IOM can involve various methods such as:

1. Electrophysiological monitoring: This includes techniques like somatosensory evoked potentials (SSEP), motor evoked potentials (MEP), and electroencephalography (EEG) to assess the integrity of neural pathways and brain function during surgery.
2. Neuromonitoring: Direct electrical stimulation of nerves or spinal cord structures can help identify critical neuroanatomical structures, evaluate their functional status, and guide surgical interventions.
3. Hemodynamic monitoring: Measuring blood pressure, heart rate, cardiac output, and oxygen saturation helps assess the patient's overall physiological status during surgery.
4. Imaging modalities: Intraoperative imaging techniques like ultrasound, computed tomography (CT), or magnetic resonance imaging (MRI) can provide real-time visualization of anatomical structures and surgical progress.

The specific IOM methods employed depend on the type of surgery, patient characteristics, and potential risks involved. Intraoperative monitoring is particularly crucial in procedures where there is a risk of neurological injury, such as spinal cord or brain surgeries, vascular interventions, or tumor resections near critical neural structures.

Resuscitation is a medical term that refers to the process of reversing cardiopulmonary arrest or preventing further deterioration of someone in cardiac or respiratory arrest. It involves a series of interventions aimed at restoring spontaneous blood circulation and breathing, thereby preventing or minimizing tissue damage due to lack of oxygen.

The most common form of resuscitation is cardiopulmonary resuscitation (CPR), which combines chest compressions to manually pump blood through the body with rescue breaths to provide oxygen to the lungs. In a hospital setting, more advanced techniques such as defibrillation, medication administration, and intubation may also be used as part of the resuscitation process.

The goal of resuscitation is to stabilize the patient's condition and prevent further harm while treating the underlying cause of the arrest. Successful resuscitation can lead to a full recovery or, in some cases, result in varying degrees of neurological impairment depending on the severity and duration of the cardiac or respiratory arrest.

Blood volume determination is a medical procedure that involves measuring the total amount of blood present in an individual's circulatory system. This measurement is typically expressed in milliliters (mL) or liters (L) and provides important information about the person's overall cardiovascular health and fluid status.

There are several methods for determining blood volume, including:

1. Direct measurement: This involves withdrawing a known volume of blood from the body, labeling the red blood cells with a radioactive or dye marker, reinfusing the cells back into the body, and then measuring the amount of marked cells that appear in subsequent blood samples over time.
2. Indirect measurement: This method uses formulas based on the person's height, weight, sex, and other factors to estimate their blood volume. One common indirect method is the "hemodynamic" calculation, which takes into account the individual's heart rate, stroke volume (the amount of blood pumped by the heart with each beat), and the concentration of hemoglobin in their red blood cells.
3. Bioimpedance analysis: This non-invasive technique uses electrical signals to measure the body's fluid volumes, including blood volume. By analyzing changes in the body's electrical conductivity in response to a small current, bioimpedance analysis can provide an estimate of blood volume.

Accurate determination of blood volume is important for assessing various medical conditions, such as heart failure, shock, anemia, and dehydration. It can also help guide treatment decisions, including the need for fluid replacement or blood transfusions.

Arterial pressure is the pressure exerted by the blood on the walls of the arteries during its flow through them. It is usually measured in millimeters of mercury (mmHg) and is expressed as two numbers: systolic and diastolic pressures. Systolic pressure is the higher value, representing the pressure when the heart contracts and pushes blood into the arteries. Diastolic pressure is the lower value, representing the pressure when the heart relaxes and fills with blood. A normal resting blood pressure for adults is typically around 120/80 mmHg.

Blood gas analysis is a medical test that measures the levels of oxygen and carbon dioxide in the blood, as well as the pH level, which indicates the acidity or alkalinity of the blood. This test is often used to evaluate lung function, respiratory disorders, and acid-base balance in the body. It can also be used to monitor the effectiveness of treatments for conditions such as chronic obstructive pulmonary disease (COPD), asthma, and other respiratory illnesses. The analysis is typically performed on a sample of arterial blood, although venous blood may also be used in some cases.

Treatment outcome is a term used to describe the result or effect of medical treatment on a patient's health status. It can be measured in various ways, such as through symptoms improvement, disease remission, reduced disability, improved quality of life, or survival rates. The treatment outcome helps healthcare providers evaluate the effectiveness of a particular treatment plan and make informed decisions about future care. It is also used in clinical research to compare the efficacy of different treatments and improve patient care.

Myelography is a medical imaging technique used to examine the spinal cord and surrounding structures, such as the spinal nerves, intervertebral discs, and the spinal column. This procedure involves the injection of a contrast dye into the subarachnoid space, which is the area surrounding the spinal cord filled with cerebrospinal fluid (CSF). The dye outlines the spinal structures, making them visible on X-ray or CT scan images.

The primary purpose of myelography is to diagnose various spinal conditions, including herniated discs, spinal stenosis, tumors, infection, and traumatic injuries. It can help identify any compression or irritation of the spinal cord or nerves that may be causing pain, numbness, weakness, or other neurological symptoms.

The procedure typically requires the patient to lie flat on their stomach or side while the radiologist inserts a thin needle into the subarachnoid space, usually at the lower lumbar level. Once the contrast dye is injected, the patient will be repositioned for various X-ray views or undergo a CT scan to capture detailed images of the spine. After the procedure, patients may experience headaches, nausea, or discomfort at the injection site, but these symptoms usually resolve within a few days.

Plasma volume refers to the total amount of plasma present in an individual's circulatory system. Plasma is the fluid component of blood, in which cells and chemical components are suspended. It is composed mainly of water, along with various dissolved substances such as nutrients, waste products, hormones, gases, and proteins.

Plasma volume is a crucial factor in maintaining proper blood flow, regulating body temperature, and facilitating the transportation of oxygen, carbon dioxide, and other essential components throughout the body. The average plasma volume for an adult human is approximately 3 liters, but it can vary depending on factors like age, sex, body weight, and overall health status.

Changes in plasma volume can have significant effects on an individual's cardiovascular function and fluid balance. For example, dehydration or blood loss can lead to a decrease in plasma volume, while conditions such as heart failure or liver cirrhosis may result in increased plasma volume due to fluid retention. Accurate measurement of plasma volume is essential for diagnosing various medical conditions and monitoring the effectiveness of treatments.

Halothane is a general anesthetic agent, which is a volatile liquid that evaporates easily and can be inhaled. It is used to produce and maintain general anesthesia (a state of unconsciousness) during surgical procedures. Halothane is known for its rapid onset and offset of action, making it useful for both induction and maintenance of anesthesia.

The medical definition of Halothane is:

Halothane (2-bromo-2-chloro-1,1,1-trifluoroethane) is a volatile liquid general anesthetic agent with a mild, sweet odor. It is primarily used for the induction and maintenance of general anesthesia in surgical procedures due to its rapid onset and offset of action. Halothane is administered via inhalation and acts by depressing the central nervous system, leading to a reversible loss of consciousness and analgesia.

It's important to note that Halothane has been associated with rare cases of severe liver injury (hepatotoxicity) and anaphylaxis (a severe, life-threatening allergic reaction). These risks have led to the development and use of alternative general anesthetic agents with better safety profiles.

Hemodiafiltration (HDF) is a type of renal replacement therapy used for patients with severe kidney failure. It combines elements of hemodialysis and hemofiltration to provide more efficient removal of waste products, toxins, and excess fluid from the blood.

During HDF, the patient's blood is passed through a semi-permeable membrane in a dialyzer or artificial kidney. The membrane allows for the passage of smaller molecules such as urea, creatinine, and electrolytes, while retaining larger molecules like proteins. A combination of diffusion (due to the concentration gradient) and convection (due to the application of a transmembrane pressure) leads to the removal of waste products and toxins from the blood.

In addition to this, a substitution fluid is infused into the extracorporeal circuit to replace the volume of fluid removed during convection. This substitution fluid can be tailored to match the patient's electrolyte and acid-base status, allowing for better control over their biochemical parameters.

HDF has been shown to provide better clearance of middle and large molecular weight uremic toxins compared to conventional hemodialysis, potentially leading to improved clinical outcomes such as reduced inflammation, oxidative stress, and cardiovascular risk. However, more research is needed to confirm these benefits and establish the optimal dosing and prescription for HDF.

Homeostasis is a fundamental concept in the field of medicine and physiology, referring to the body's ability to maintain a stable internal environment, despite changes in external conditions. It is the process by which biological systems regulate their internal environment to remain in a state of dynamic equilibrium. This is achieved through various feedback mechanisms that involve sensors, control centers, and effectors, working together to detect, interpret, and respond to disturbances in the system.

For example, the body maintains homeostasis through mechanisms such as temperature regulation (through sweating or shivering), fluid balance (through kidney function and thirst), and blood glucose levels (through insulin and glucagon secretion). When homeostasis is disrupted, it can lead to disease or dysfunction in the body.

In summary, homeostasis is the maintenance of a stable internal environment within biological systems, through various regulatory mechanisms that respond to changes in external conditions.

The brain is the central organ of the nervous system, responsible for receiving and processing sensory information, regulating vital functions, and controlling behavior, movement, and cognition. It is divided into several distinct regions, each with specific functions:

1. Cerebrum: The largest part of the brain, responsible for higher cognitive functions such as thinking, learning, memory, language, and perception. It is divided into two hemispheres, each controlling the opposite side of the body.
2. Cerebellum: Located at the back of the brain, it is responsible for coordinating muscle movements, maintaining balance, and fine-tuning motor skills.
3. Brainstem: Connects the cerebrum and cerebellum to the spinal cord, controlling vital functions such as breathing, heart rate, and blood pressure. It also serves as a relay center for sensory information and motor commands between the brain and the rest of the body.
4. Diencephalon: A region that includes the thalamus (a major sensory relay station) and hypothalamus (regulates hormones, temperature, hunger, thirst, and sleep).
5. Limbic system: A group of structures involved in emotional processing, memory formation, and motivation, including the hippocampus, amygdala, and cingulate gyrus.

The brain is composed of billions of interconnected neurons that communicate through electrical and chemical signals. It is protected by the skull and surrounded by three layers of membranes called meninges, as well as cerebrospinal fluid that provides cushioning and nutrients.

A headache is defined as pain or discomfort in the head, scalp, or neck. It can be a symptom of various underlying conditions such as stress, sinus congestion, migraine, or more serious issues like meningitis or concussion. Headaches can vary in intensity, ranging from mild to severe, and may be accompanied by other symptoms such as nausea, vomiting, or sensitivity to light and sound. There are over 150 different types of headaches, including tension headaches, cluster headaches, and sinus headaches, each with their own specific characteristics and causes.

Central venous pressure (CVP) is the blood pressure measured in the large veins that enter the right atrium of the heart. It reflects the amount of blood returning to the heart and the ability of the heart to pump it effectively. CVP is used as an indicator of a person's intravascular volume status, cardiac function, and overall hemodynamic performance. The measurement is taken using a central venous catheter placed in a large vein such as the internal jugular or subclavian vein. Normal CVP values range from 0 to 8 mmHg (millimeters of mercury) in adults when measured at the level of the right atrium.

Ganglionic blockers are a type of medication that blocks the activity of the ganglia, which are clusters of nerve cells located outside the central nervous system. These medications work by blocking the transmission of nerve impulses between the ganglia and the effector organs they innervate, such as muscles or glands.

Ganglionic blockers were once used in the treatment of various conditions, including hypertension (high blood pressure), peptic ulcers, and certain types of pain. However, their use has largely been abandoned due to their significant side effects, which can include dry mouth, blurred vision, constipation, difficulty urinating, and dizziness or lightheadedness upon standing.

There are two main types of ganglionic blockers: nicotinic and muscarinic. Nicotinic ganglionic blockers block the action of acetylcholine at nicotinic receptors in the ganglia, while muscarinic ganglionic blockers block the action of acetylcholine at muscarinic receptors in the ganglia.

Examples of ganglionic blockers include trimethaphan, hexamethonium, and pentolinium. These medications are typically administered intravenously in a hospital setting due to their short duration of action and potential for serious side effects.

Nitric oxide (NO) is a molecule made up of one nitrogen atom and one oxygen atom. In the body, it is a crucial signaling molecule involved in various physiological processes such as vasodilation, immune response, neurotransmission, and inhibition of platelet aggregation. It is produced naturally by the enzyme nitric oxide synthase (NOS) from the amino acid L-arginine. Inhaled nitric oxide is used medically to treat pulmonary hypertension in newborns and adults, as it helps to relax and widen blood vessels, improving oxygenation and blood flow.

Familial dysautonomia (FD) is a genetic disorder that affects the autonomic nervous system (ANS), which controls automatic functions such as heart rate, blood pressure, body temperature, and digestion. It is also known as Riley-Day syndrome or Hereditary Sensory and Autonomic Neuropathy Type III (HSAN III).

FD is caused by a mutation in the IKBKAP gene, which provides instructions for making a protein that is essential for the development and function of certain nerves. The condition is inherited in an autosomal recessive manner, meaning that an individual must inherit two copies of the mutated gene (one from each parent) to have the disease.

The symptoms of familial dysautonomia can vary widely, but often include:

* Difficulty regulating blood pressure and heart rate, leading to fluctuations in blood pressure, dizziness, and fainting spells
* Poor temperature regulation, causing episodes of sweating or flushing
* Difficulty swallowing and poor muscle tone in the face and tongue
* Absent or reduced deep tendon reflexes
* Delayed growth and development
* Reduced sensitivity to pain and temperature changes
* Emotional lability and behavioral problems

There is no cure for familial dysautonomia, but treatment can help manage symptoms and improve quality of life. Treatment may include medications to regulate blood pressure and heart rate, physical therapy to improve muscle tone and coordination, and feeding tubes or special diets to ensure adequate nutrition.

Vasopressin, also known as antidiuretic hormone (ADH), is a hormone that helps regulate water balance in the body. It is produced by the hypothalamus and stored in the posterior pituitary gland. When the body is dehydrated or experiencing low blood pressure, vasopressin is released into the bloodstream, where it causes the kidneys to decrease the amount of urine they produce and helps to constrict blood vessels, thereby increasing blood pressure. This helps to maintain adequate fluid volume in the body and ensure that vital organs receive an adequate supply of oxygen-rich blood. In addition to its role in water balance and blood pressure regulation, vasopressin also plays a role in social behaviors such as pair bonding and trust.

Epinephrine, also known as adrenaline, is a hormone and a neurotransmitter that is produced in the body. It is released by the adrenal glands in response to stress or excitement, and it prepares the body for the "fight or flight" response. Epinephrine works by binding to specific receptors in the body, which causes a variety of physiological effects, including increased heart rate and blood pressure, improved muscle strength and alertness, and narrowing of the blood vessels in the skin and intestines. It is also used as a medication to treat various medical conditions, such as anaphylaxis (a severe allergic reaction), cardiac arrest, and low blood pressure.

Fentanyl is a potent synthetic opioid analgesic, which is similar to morphine but is 50 to 100 times more potent. It is a schedule II prescription drug, typically used to treat patients with severe pain or to manage pain after surgery. It works by binding to the body's opioid receptors, which are found in the brain, spinal cord, and other areas of the body.

Fentanyl can be administered in several forms, including transdermal patches, lozenges, injectable solutions, and tablets that dissolve in the mouth. Illegally manufactured and distributed fentanyl has also become a major public health concern, as it is often mixed with other drugs such as heroin, cocaine, and counterfeit pills, leading to an increase in overdose deaths.

Like all opioids, fentanyl carries a risk of dependence, addiction, and overdose, especially when used outside of medical supervision or in combination with other central nervous system depressants such as alcohol or benzodiazepines. It is important to use fentanyl only as directed by a healthcare provider and to be aware of the potential risks associated with its use.

"Wistar rats" are a strain of albino rats that are widely used in laboratory research. They were developed at the Wistar Institute in Philadelphia, USA, and were first introduced in 1906. Wistar rats are outbred, which means that they are genetically diverse and do not have a fixed set of genetic characteristics like inbred strains.

Wistar rats are commonly used as animal models in biomedical research because of their size, ease of handling, and relatively low cost. They are used in a wide range of research areas, including toxicology, pharmacology, nutrition, cancer, cardiovascular disease, and behavioral studies. Wistar rats are also used in safety testing of drugs, medical devices, and other products.

Wistar rats are typically larger than many other rat strains, with males weighing between 500-700 grams and females weighing between 250-350 grams. They have a lifespan of approximately 2-3 years. Wistar rats are also known for their docile and friendly nature, making them easy to handle and work with in the laboratory setting.

Inhalational anesthesia is a type of general anesthesia that is induced by the inhalation of gases or vapors. It is administered through a breathing system, which delivers the anesthetic agents to the patient via a face mask, laryngeal mask airway, or endotracheal tube.

The most commonly used inhalational anesthetics include nitrous oxide, sevoflurane, isoflurane, and desflurane. These agents work by depressing the central nervous system, causing a reversible loss of consciousness, amnesia, analgesia, and muscle relaxation.

The depth of anesthesia can be easily adjusted during the procedure by changing the concentration of the anesthetic agent. Once the procedure is complete, the anesthetic agents are eliminated from the body through exhalation, allowing for a rapid recovery.

Inhalational anesthesia is commonly used in a wide range of surgical procedures due to its ease of administration, quick onset and offset of action, and ability to rapidly adjust the depth of anesthesia. However, it requires careful monitoring and management by trained anesthesia providers to ensure patient safety and optimize outcomes.

Orthostatic hypotension, also called postural hypotension, is a common form of low blood pressure. It occurs after a change in ... Chronic use of alpha blockers or beta blockers can lead to hypotension. Beta blockers can cause hypotension both by slowing the ... However, since it focuses on hypotension due to infection, it is not applicable to all forms of severe hypotension. Volume ... Some medications can also lead to hypotension. There are also syndromes that can cause hypotension in patients including ...
... (or postural hypotension) is a drop in blood pressure upon standing. One definition (AAFP) calls for a ... Primary orthostatic hypotension is also often referred to as neurogenic orthostatic hypotension. The drop in blood pressure may ... Orthostatic hypotension, also known as postural hypotension, is a medical condition wherein a person's blood pressure drops ... Alcohol can potentiate orthostatic hypotension to the point of syncope. Orthostatic hypotension can also be a side effect of ...
... relies on the heart's ability to pump fluid through the body efficiently. Less intravascular fluid ... Applying permissive hypotension to the latter patient category may result in decreased coronary perfusion and result in ... The results from the Traumatic Coma Data Bank show the influence of the presence or absence of hypotension (defined as one or ... Permissive hypotension or hypotensive resuscitation is the use of restrictive fluid therapy, specifically in the trauma patient ...
Orthostatic hypotension occurs when there is a persistent reduction in blood pressure of at least 20mmHg systolic or 10mmHg ... Neurogenic orthostatic hypotension showed a prevalence of 18% in patients older than 65 years and resulted in syncope in 9.4% ... As described above, orthostatic hypotension diagnosis is when there is a drop of greater than or equal to 20 mmHg or greater or ... Orthostatic hypotension is one of the most frequently identified causes of syncope in the general population. Effective ...
Tidy C (February 2013). Cox J (ed.). "Hypotension". Patient.info. Archived from the original on 28 August 2021. Retrieved 26 ... Similarly, octreotide can be used to treat refractory chronic hypotension. While successful treatment has been demonstrated in ...
20/10 mm Hg) is termed orthostatic hypotension (postural hypotension) and represents a failure of the body to compensate for ... Both hypertension and hypotension have many causes and may be of sudden onset or of long duration. Long-term hypertension is a ... Blood pressure that is too low is called hypotension, pressure that is consistently too high is called hypertension, and normal ... Long-term hypertension is more common than long-term hypotension. The risk of cardiovascular disease increases progressively ...
Blood pressure Hypertension Hypotension Systemic vascular resistance Pulse pressure Zheng L, Sun Z, Li J, Zhang R, Zhang X, Liu ... When assessing hypotension, the context of the baseline blood pressure needs to be considered. Acute decreases in mean arterial ... Jones D, Francesco L (2017). "Hypotension". In McKean SC, Ross JJ, Dressler DD, Scheurer DB (eds.). Principles and Practice of ...
"Postural hypotension". Walker et al. 2015, p. 1687. Tsamakis & Mueller 2021, pp. 2-3. Tsamakis & Mueller 2021, pp. 1, 4. Tahami ... Between 50 and 60% of individuals with DLB have orthostatic hypotension due to reduced blood flow, which can result in ... The severity of orthostatic hypotension also predicts a worse prognosis. Visuospatial deficits early in the course of DLB were ... Decreasing the dosage of dopaminergic or atypical antipsychotic drugs may be needed with orthostatic hypotension, and high ...
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Here, however, increased CO cannot solve the structural problems causing renal artery hypotension, with the result that CO ... Larsen R, Kleinschmidt S (April 1995). "[Controlled hypotension]". Der Anaesthesist (in German). 44 (4): 291-308. doi:10.1007/ ...
However, significant hypotension may occur, if a patient sits up too quickly from the supine position or becomes oversedated, ... Severe hypotension. Nitrous oxide causes a decrease in blood pressure due to a reduction in sympathetic function. ...
Mattox, Kenneth L. (January 2003). "Permissive Hypotension". 8:1. trauma.org. {{cite journal}}: Cite journal requires ,journal ... v t e Compression garment Hemostasis Hypovolemia Permissive hypotension Shock (circulatory) Chatham, Strecker-McGraw (2022). " ...
"Permissive Hypotension". Trauma.Org. 1997-08-31. Archived from the original on 2013-11-27. Retrieved 2015-11-01. Kennamer M, ... These include oliguria, cyanosis, abdominal and chest pain, hypotension, tachycardia, cold hands and feet, and progressively ... Current best practice allow permissive hypotension in patients with hypovolemic shock, both avoid overly diluting clotting ...
Postprandial hypotension is a drastic decline in blood pressure which happens after eating a meal. Postprandial regurgitation ... "Postprandial Hypotension." Last revised February 2003. Last accessed July 13, 2007. (Articles with short description, Short ...
... essential hypotension; first functional class of stable angina strain of heart ischemic disease; miocardiodistrophies of ...
Severe hypotension. Persons with cardiac conditions including hypotension, mechanical heart failure (valvular, pulmonary ... Ramirez J (November 2013). "Severe hypotension associated with α blocker tamsulosin". BMJ. 347: f6492. doi:10.1136/bmj.f6492. ... "Tamsulosin treatment for benign prostatic hyperplasia and risk of severe hypotension in men aged 40-85 years in the United ...
Hypoadrenergic orthostatic hypotension occurs when the person is unable to sustain a normal sympathetic response to blood ... Closely related to other causes of syncope related to hypotension (low blood pressure) such as orthostatic syncope. Lactose ... However, the resulting "transient orthostatic hypotension" does not necessarily signal any serious underlying disease. It is as ... and orthostatic hypotension. Issues with the heart and blood vessels are the cause in about 10% and typically the most serious ...
Symptoms have been edema of the face and tongue, or larynx; shortness of breath; wheezing; chest pain; hypotension (including ...
Instantaneous hypotension due to sudden, massive vasodilation and decrease in blood oxygen saturation Warm, flushed skin due to ... "Hypotension & Shock Treatment , health.am". Holtz, Anders; Levi, Richard (6 July 2010). Spinal Cord Injury. Oxford University ... Neurogenic shock is a distributive type of shock resulting in hypotension (low blood pressure), often with bradycardia (slowed ... "Neurogenic Hypotension in Patients with Severe Head Injuries". The Journal of Trauma: Injury, Infection, and Critical Care. 44 ...
"Hypotension and flying". Lancet. 232 (2): 1503-10. doi:10.1016/s0140-6736(00)83970-7. Wood, EH (Jul 1987). "Development of anti ...
Shy GM, Drager GA (May 1960). "A neurological syndrome associated with orthostatic hypotension: a clinical-pathologic study". ... ISBN 978-3-540-23735-8. "Autonomic nervous system" at Dorland's Medical Dictionary "Hypotension". The Lecturio Medical Concept ... postural or orthostatic hypotension, resulting in dizziness or fainting upon standing up urinary incontinence or urinary ... "Management of Orthostatic Hypotension". Continuum. 26 (1): 154-177. doi:10.1212/CON.0000000000000816. PMC 7339914. PMID ...
These include ischemia (insufficient blood flow); cerebral hypoxia (insufficient oxygen in the brain); hypotension (low blood ...
The reported list of possible side effects derived from the consumption of medical cannabis include tachycardia, hypotension, ... inducing hypotension within glaucomas; managing neurological diseases, such as spasticity caused by multiple sclerosis, ...
Patients who need alpha blockers for BPH, but have a history of hypotension or postural heart failure, should use these drugs ... Ultimately, this gives rise to orthostatic hypotension, dizziness, and a sudden loss of consciousness due to the drastic drop ... Again, these interactions can cause dangerous hypotension. Furthermore, in rare cases, drug interactions can cause irregular, ... orthostatic hypotension, or heart palpitations via alterations of the QT interval. Alpha blockers that may have these side ...
Infrequent ADRs include hypotension. Rare ADRs include: headache, tiredness, dizziness, confusion, diarrhea, constipation, and ...
Cardiovascular: Myocardial infarction; stroke; heart block; arrhythmias; hypotension, particularly orthostatic hypotension; ... Critical manifestations of overdose include: cardiac dysrhythmias, severe hypotension, convulsions, and CNS depression, ...
Hypotension and shock ensue. If not rapidly treated, it can lead to cardiac arrest and death. A pulmonary embolism (PE) is an ... The triad includes hypotension, jugular vein distension, and muffled heart sounds. Kussmaul's sign and pulsus paradoxus may ... When severe enough to cause these shifts and hypotension, it is called a tension pneumothorax. This is life-threatening. The ... A PE is considered "massive" when it causes hypotension or shock. A submassive PE causes right heart dysfunction without ...
Intradialytic hypotension (IDH) or hemodialysis-induced hypotension. Freezing of gait in Parkinson's disease (off-label) With ... Palma JA, Kaufmann H (February 2020). "Management of Orthostatic Hypotension". Continuum. 26 (1): 154-177. doi:10.1212/CON. ... Mathias CJ (March 2008). "L-dihydroxyphenylserine (Droxidopa) in the treatment of orthostatic hypotension: the European ... July 2014). "Droxidopa for neurogenic orthostatic hypotension: a randomized, placebo-controlled, phase 3 trial". Neurology. 83 ...
... hypotension) • increased heart rate (tachycardia) These effects are seen as part of the spiritual purification/healing process ...
It is the drug of choice for people in traumatic shock who are at risk of hypotension. Low blood pressure is dangerous for ... Nickson C (7 August 2013). "Intubation, Hypotension and Shock". Life in the Fastlane (blog). Critical Care Compendium. Archived ... Hemmingsen C, Nielsen JE (November 1991). "Intravenous ketamine for prevention of severe hypotension during spinal anaesthesia ... "Hypotension, hypoxia, and head injury: frequency, duration, and consequences". Archives of Surgery. 136 (10): 1118-23. doi: ...
Orthostatic hypotension, also called postural hypotension, is a common form of low blood pressure. It occurs after a change in ... Chronic use of alpha blockers or beta blockers can lead to hypotension. Beta blockers can cause hypotension both by slowing the ... However, since it focuses on hypotension due to infection, it is not applicable to all forms of severe hypotension. Volume ... Some medications can also lead to hypotension. There are also syndromes that can cause hypotension in patients including ...
Orthostatic hypotension is a drop in blood pressure that occurs when moving from a laying down (supine) position to a standing ... Orthostatic hypotension has two forms that result from two main causes.. The neurogenic form is caused by problems with the ... Orthostatic hypotension is a drop in blood pressure that occurs when moving from a laying down (supine) position to a standing ... Orthostatic Hypotension: JACC State-of-the-Art Review. J Am Coll Cardiol. 2018 Sep 11;72(11):1294-1309. doi: 10.1016/j.jacc. ...
Asymptomatic orthostatic hypotension and standing hypotension should not deter adoption of more intensive antihypertensive ... "These findings suggest that orthostatic hypotension alone (ie, without symptoms) and standing hypotension measured prior to ... Cite this: Orthostatic Hypotension No Deterrent to Hypertension Treatment - Medscape - Oct 24, 2023. ... Some trials excluded adults with low standing systolic BP, limiting the number of participants with standing hypotension. OH ...
Many conditions and pathophysiologic disturbances are associated with shock and hypotension in the newborn, ranging from acute ... encoded search term (Shock and Hypotension in the Newborn) and Shock and Hypotension in the Newborn What to Read Next on ... Shock and Hypotension in the Newborn. Updated: Nov 27, 2021 * Author: Samir Gupta, MD, DM, FRCPCH, FRCPI; Chief Editor: ... Schmaltz C. Hypotension and shock in the preterm neonate. Adv Neonatal Care. 2009 Aug. 9(4):156-62. [QxMD MEDLINE Link]. ...
La Jolla reports additional Phase III data for LJPC-501 in catecholamine-resistant hypotension. Claire Quang ... to treat hypotension in adults with distributive or vasodilatory shock who remain hypotensive despite fluid and vasopressor ... international trial enrolled 321 evaluable critically ill patients with catecholamine-resistant hypotension on a background of ...
Orthostatic Hypotension. Does Orthostatic Hypotension Mean a Return to my G-Suit?. by Duane Graveline, MD MPH ... By placing our subjects in comfortable beds we soon learned that postural hypotension would soon be a major adversary. Just as ... Now, in the International Space Station, 80% of occupants will have a marked tendency for postural hypotension on return to ... Our subjects were experiencing postural hypotension and several days might be required before normal blood pressure response ...
Autonomic dysfunction, Carotid sinus, Delayed orthostatic hypotension, Postprandial hypotension, Postural orthostatic ... Other syndromes of orthostatic intolerance : Delayed orthostatic hypotension, postprandial hypotension, postural orthostatic ... Orthostatic Hypotension in Older Adults editor. Turan Isik, A and Soysal, P pages. 23 pages. publisher. Springer International ... Delayed orthostatic hypotension, postprandial hypotension, postural orthostatic tachycardia syndrome, and reflex syncope}}, url ...
Orthostatic Hypotension - Etiology, pathophysiology, symptoms, signs, diagnosis & prognosis from the MSD Manuals - Medical ... Evaluation of Orthostatic Hypotension Orthostatic hypotension is diagnosed when systolic BP drops by ≥ 20 mm Hg or diastolic BP ... Geriatrics Essentials: Orthostatic Hypotension Orthostatic hypotension occurs in about 20% of older adults it is more common ... see table Causes of Orthostatic Hypotension Causes of Orthostatic Hypotension ), particularly antihypertensives and nitrates. A ...
Its also called fainting or "passing out." It most often occurs when blood pressure is too low (hypotension) and the heart ...
Beconase and Hypotension. This page shows results related to Beconase and Hypotension from the FDA Adverse Event Reporting ...
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Intracranial hypotension is a disorder of CSF hypovolemia due to iatrogenic or spontaneous spinal CSF leakage. Rarely, ... Intracranial hypotension producing reversible coma: a systematic review, including three new cases A review JOURNAL OF ... Intracranial hypotension was diagnosed in most patients via MRI studies, which were often obtained due to failure to improve ... Intracranial hypotension is a disorder of CSF hypovolemia due to iatrogenic or spontaneous spinal CSF leakage. Rarely, ...
In this situation we have a gentleman with groin pain and hypotension, our clinical question is as follows, "Is there a AAA - ... Based on the literature, we can confidently rule out AAA as the source of our patients hypotension [1]. Additionally, we can ... Focus on POCUS: Crackles and Hypotension. by Robert Suttie , Dec 6, 2018 , 0 comments ...
NECTAR ELIXIR PRIVATE LIMITED is a leading Manufacturer and Supplier of Orthostatic Hypotension in Gujarat, India & nearby area ... Get Orthostatic Hypotension at best price with product details. ...
5.9 Orthostatic Hypotension. Ziprasidone may induce orthostatic hypotension associated with dizziness, tachycardia, and, in ... 5.9 Orthostatic Hypotension 5.10 Falls 5.11 Leukopenia, Neutropenia, and Agranulocytosis 5.12 Seizures 5.13 Dysphagia 5.14 ... Vital Sign Changes -Ziprasidone is associated with orthostatic hypotension [see Warnings and Precautions (5.9)] ECG Changes - ... Orthostatic Hypotension: Use with caution in patients with known cardiovascular or cerebrovascular disease. (5.9) ...
Perioperative Hypotension.. We studied intraoperative and postoperative hypotension as dichotomous variables. Depending on the ... 2) Any hypotension + coronary computed tomographic angiography findings + any hypotension × coronary computed tomographic ... 4) Intraoperative hypotension + postoperative hypotension + coronary computed tomographic angiography findings + intraoperative ... or postoperative hypotension) or as two separate variables. Intraoperative hypotension was defined as systolic blood pressure ...
Data updated last 04/11/2024 22:30 10:30:01 PM ...
... to be more effective in terms of managing hypotension as compared to administering crystalloid before spinal anesthesia ( ... Hypotension was virtually eliminated by use of high-dose prophylactic phenylephrine infusion at a rate of 100 µg/min and rapid ... The bolus administration of phenylephrine to treat hypotension is still commonly used, but requests multiple interventions from ... Variable Rate Phenylephrine Infusion for Prevention of Spinal-induced Hypotension for Cesarean Delivery. ...
Find tables and figures with additional harmful algal bloom and illness data from CDCs 2016-2018 One Health Harmful Algal Bloom System (OHHABS) report.
Hypotension [117]. Reduced systolic and diastolic blood pressure [118]. Reduced stress and anxiety. [117]. ...
Hypotension: Administer a vasopressor, e.g., norepinephrine or dopamine.. Bronchospasm: Administer a beta2-stimulating agent ... Subjects were ineligible if they had hypotension, bradycardia, peripheral signs of shock, and/or more than minimal basal rates ... Observe patients treated with metoprolol tartrate plus a catecholamine depletor for evidence of hypotension or marked ... Potential signs and symptoms associated with overdosage with metoprolol tartrate are bradycardia, hypotension, bronchospasm, ...
Hypotension. It occurs in 25-55% of hemodialysis treatments. Variations in blood pressure are caused by a decrease in blood ... Dialysis-associated hypotension should be managed acutely by discontinuing ultrafiltration, administration of 100-250 ml of ... Diazepam has also been shown to treat dialysis-associated muscle cramps effectively, but it may also cause hypotension. Quinine ... Categorize the etiology and treatment of intradialytic hypotension.. *Relate the three causes of allergic reactions to ...
The MAP and Hypotension Prediction Index signals show an inverted trend, i.e., when MAP decreases, the Hypotension Prediction ... The Hypotension Prediction Index alarm started 3.0 [1.0 to 8.9] min before hypotension occurred, with a concurrent MAP of 71 [ ... 1) might yield a prediction of intraoperative hypotension comparable to the Hypotension Prediction Index. In line with our ... When a Hypotension Prediction Index alarm was present, the MAP was 75 mmHg or less 94% of the time. When a threshold of MAP 70 ...
Vasopressin for Refractory Hypotension During Cardiopulmonary Bypass Issue: Vol 56, Issue 6 (2007) ...
This guideline covers general principles for managing intravenous (IV) fluids for children and young people under 16 years, including assessing fluid and electrolyte status and prescribing IV fluid therapy. It applies to a range of conditions and different settings. It does not include recommendations relating to specific conditions. This guideline represents a major opportunity to improve patient safety for children and young people having IV fluid therapy in hospital
The patient was admitted to our department of internal medicine because of the symptoms flushing, hypotension and episodes of ...
Hypotension, unspecified. I99.9. Unspecified disorder of circulatory system. J00. Acute nasopharyngitis [common cold]. ...
2. Orthostatic Hypotension. A drop in blood pressure can also cause lightheadedness or dizziness when lying down and getting up ... What causes orthostatic hypotension? Mild dehydration, or being low on fluids, can make it harder to control blood pressure. ... How do you prevent orthostatic hypotension? To help keep blood flowing, move your feet and legs, and dont stand still in one ... The primary causes of dizziness when lying down are benign paroxysmal positional vertigo (BPPV) and orthostatic hypotension. ...
  • There are also syndromes that can cause hypotension in patients including orthostatic hypotension, vasovagal syncope, and other rarer conditions. (wikipedia.org)
  • Orthostatic hypotension is a drop in blood pressure that occurs when moving from a laying down (supine) position to a standing (upright) position. (medlineplus.gov)
  • However, this transient orthostatic hypotension can cause lightheadedness that may result in falls and injury, particularly in older adults. (medlineplus.gov)
  • The body has difficulty achieving stable blood pressure in people with orthostatic hypotension, resulting in a prolonged drop in blood pressure that occurs within minutes after moving from laying down to standing. (medlineplus.gov)
  • When measuring blood pressure, orthostatic hypotension is defined as a decrease in blood pressure by at least 20mmHg systolic or 10mmHg diastolic within 3 minutes of standing. (medlineplus.gov)
  • When signs and symptoms of orthostatic hypotension do occur, they are usually the result of a reduction in blood flow (hypoperfusion) to tissues, particularly the brain. (medlineplus.gov)
  • During an episode of orthostatic hypotension, symptoms are often increased in severity by physical activity, warm temperatures, eating large meals, or standing for long periods of time. (medlineplus.gov)
  • Orthostatic hypotension is a common condition that affects about 6 percent of the population. (medlineplus.gov)
  • Orthostatic hypotension has two forms that result from two main causes. (medlineplus.gov)
  • Disorders that affect the autonomic nervous system can impair the adjustment of blood pressure, leading to orthostatic hypotension. (medlineplus.gov)
  • Neurogenic orthostatic hypotension often occurs along with nervous system disorders such as Parkinson's disease , dementia with Lewy bodies , multiple system atrophy , pure autonomic failure, diabetes, Guillain-Barré syndrome , dopamine beta-hydroxylase deficiency , or infections that cause disturbances in nerve function (neuropathy). (medlineplus.gov)
  • The non-neurogenic form of orthostatic hypotension is often caused by environmental or health factors that impair the body's mechanisms to stabilize blood pressure upon standing. (medlineplus.gov)
  • Certain medications can also contribute to non-neurogenic orthostatic hypotension, such as antipsychotic or antidepressant drugs, drugs that treat high blood pressure by widening blood vessels (vasodilators), or drugs that help remove water and salt from the body (diuretics). (medlineplus.gov)
  • The non-neurogenic form of orthostatic hypotension is more common than the neurogenic form, but in about 40 percent of people with orthostatic hypotension the underlying cause is unknown (idiopathic). (medlineplus.gov)
  • Intensive antihypertensive treatment provides the same benefit with regard to cardiovascular disease (CVD) and all-cause mortality regardless of the presence or absence of orthostatic or standing hypotension, new research shows. (medscape.com)
  • In response to ongoing concern about the benefits of intensive vs standard blood pressure (BP) treatment for adults with orthostatic hypotension (OH), researchers conducted a meta-analysis of individual patient data from nine randomized clinical trials to see whether the benefit of antihypertensive treatment was diminished for patients who had OH at baseline. (medscape.com)
  • These findings suggest that orthostatic hypotension alone (ie, without symptoms) and standing hypotension measured prior to intensification of BP treatment should not deter adoption of more intensive BP treatment in adults with hypertension ," the authors conclude. (medscape.com)
  • Cite this: Orthostatic Hypotension No Deterrent to Hypertension Treatment - Medscape - Oct 24, 2023. (medscape.com)
  • Does Orthostatic Hypotension Mean a Return to my G-Suit? (spacedoc.com)
  • Apart from classical orthostatic hypotension, the gravitational force may strongly contribute to other forms of orthostatic intolerance, delayed and postprandial OH, postural orthostatic tachycardia syndrome (POTS), and reflex syncope. (lu.se)
  • Orthostatic (postural) hypotension is an excessive fall in blood pressure (BP) when an upright position is assumed. (msdmanuals.com)
  • Orthostatic hypotension is a manifestation of abnormal BP regulation due to various conditions, not a specific disorder. (msdmanuals.com)
  • Postprandial orthostatic hypotension is also common. (msdmanuals.com)
  • The primary causes of dizziness when lying down are benign paroxysmal positional vertigo (BPPV) and orthostatic hypotension. (doctorshealthpress.com)
  • Low blood pressure caused by standing or sitting up too quickly from a lying down position is what is known as orthostatic hypotension. (doctorshealthpress.com)
  • Physical examination reveals a pale thin woman with orthostatic hypotension. (proprofs.com)
  • The patient's symptoms of abdominal pain, weight loss, and diarrhea, along with the physical examination findings of a pale thin woman with orthostatic hypotension, suggest a chronic inflammatory condition. (proprofs.com)
  • By placing our subjects in comfortable beds we soon learned that postural hypotension would soon be a major adversary. (spacedoc.com)
  • Just as hypertension means excess blood pressure, postural hypotension means insufficient blood pressure while standing upright. (spacedoc.com)
  • Our subjects were experiencing postural hypotension and several days might be required before normal blood pressure response ensued. (spacedoc.com)
  • Now, in the International Space Station, 80% of occupants will have a marked tendency for postural hypotension on return to Earth after their six- month missions despite some 2.5 hours each day in self-maintenance exercises, intensive rehydration prior to de-orbit and the use of anti-G suits. (spacedoc.com)
  • To assess cardiac autonomic modulation during perioperative hypotension caused by subarachnoid anesthesia. (bvsalud.org)
  • 20 min after the blockade was installed, and at the time of motor function recovery according to the Bromage criteria and prognostic indices will be evaluated in the development of perioperative hypotension in two groups. (bvsalud.org)
  • Phenylehrine infusion is a safe and effective way to reduce incidence and frequency of hypotension during SA for cesarean delivery. (veeva.com)
  • Maternal hyperuricemia as a marker of post-spinal hypotension and uterine tone during cesarean delivery: a prospective observational study. (bvsalud.org)
  • In healthy, normotensive parturients undergoing emergency cesarean delivery, maternal hyperuricemia is associated with lower incidence of post-spinal hypotension and reduced need of vasopressors. (bvsalud.org)
  • Poor perfusion due to hypotension, hypovolemic shock, or cold extremities. (who.int)
  • Based on the literature, we can confidently rule out AAA as the source of our patient's hypotension [1] . (emottawablog.com)
  • Representative time course of a patient's Hypotension Prediction Index ( blue ) and MAP ( red ) before, during, and after an alarm ( gray shaded ) and intraoperative hypotensive event ( red shaded ). (anesthesiaexperts.com)
  • Representative example of a patient's cross-correlation coefficient between the Hypotension Prediction Index and MAP signals. (anesthesiaexperts.com)
  • The patient was admitted to our department of internal medicine because of the symptoms flushing, hypotension and episodes of syncope. (scirp.org)
  • Decreased cardiac output despite normal blood volume, due to severe congestive heart failure, large myocardial infarction, heart valve problems, or extremely low heart rate (bradycardia), often produces hypotension and can rapidly progress to cardiogenic shock. (wikipedia.org)
  • Intracranial hypotension is a disorder of CSF hypovolemia due to iatrogenic or spontaneous spinal CSF leakage. (stanford.edu)
  • The literature review revealed that numerous additional patients with clinical histories consistent with intracranial hypotension but no radiological confirmation developed SDH following a spinal procedure. (stanford.edu)
  • Rapid administration of crystalloid immediately after induction of spinal anesthesia (coload) to be more effective in terms of managing hypotension as compared to administering crystalloid before spinal anesthesia (preload). (veeva.com)
  • A rise in serum uric acid levels has also been reported during labor, warranting its correlation with post-spinal hypotension and uterine tone. (bvsalud.org)
  • Following spinal anesthesia we recorded episodes of hypotension (MAP (bvsalud.org)
  • appropriate for gestation age) and its correlation with post-spinal hypotension . (bvsalud.org)
  • In this situation we have a gentleman with groin pain and hypotension, our clinical question is as follows, "Is there a AAA - yes or no" and, "Is there hydronephrosis - yes or no. (emottawablog.com)
  • This led us to perform a detailed comparison between the two signals in clinical practice, and investigate the relationship between Hypotension Predicting Index alarms and different simultaneously assessed MAP alarms, to further clarify the presumed added value of the Hypotension Prediction Index over MAP. (anesthesiaexperts.com)
  • Clinical question: What's the effect of restrictive versus liberal fluid resuscitation strategies in sepsis-induced hypotension on 90-day mortality? (the-hospitalist.org)
  • Treatment of hypotension may include the use of intravenous fluids or vasopressors. (wikipedia.org)
  • [ 3 ] In a study of the variation in the prevalence of hypotension among low-birth-weight infants, 16-52% received volume expansion and 4-39% received vasopressors. (medscape.com)
  • The double-blind, international trial enrolled 321 evaluable critically ill patients with catecholamine-resistant hypotension on a background of standard of care (SOC) vasopressors. (biocentury.com)
  • Categorize the etiology and treatment of intradialytic hypotension. (ceufast.com)
  • Excessive vasodilation, or insufficient constriction of the blood vessels (mostly arterioles), causes hypotension. (wikipedia.org)
  • Other medications can produce hypotension by different mechanisms. (wikipedia.org)
  • Systemic hypotension is a medical emergency and will cause end-organ injury if not reversed. (nih.gov)
  • Controlled hypotension is an anaesthetic technique in which there is deliberate reduction of systemic blood pressure during anaesthesia. (bvsalud.org)
  • The findings should "reassure clinicians that patients with OH (and perhaps standing hypotension) will derive the full expected benefits from antihypertensive therapy," add the authors of an accompanying editorial. (medscape.com)
  • Intracranial hypotension was diagnosed in most patients via MRI studies, which were often obtained due to failure to improve after subdural hematoma (SDH) evacuation. (stanford.edu)
  • Once the diagnosis of intracranial hypotension was made, placement of epidural blood patches was curative in 85% of patients. (stanford.edu)
  • To facilitate recognition of this treatable but potentially life-threatening condition, the authors propose criteria that should prompt intracranial hypotension workup in the comatose patient and present a stepwise management algorithm to guide the appropriate diagnosis and treatment of these patients. (stanford.edu)
  • In an observational pilot study, the Hypotension Prediction Index was used in addition to routine monitoring in the operating room on a convenience sample of 33 adult, high-risk noncardiac surgery patients requiring invasive blood pressure monitoring (local ethical committee waived approval [#K22-42], Medisch Spectrum Twente, Enschede, The Netherlands). (anesthesiaexperts.com)
  • At least one Hypotension Prediction Index alarm (default threshold of 85 or greater) was detected in 28 (85%) patients, with a total alarm duration of 25.8 [8.1 to 41.3] min for this subgroup. (anesthesiaexperts.com)
  • Hypotension, defined as MAP less than 65 mmHg for at least 1 min, was recorded in 18 (55%) patients, with a total duration of 7.7 [4.2 to 17.8] min for this subgroup. (anesthesiaexperts.com)
  • A systolic blood pressure of less than 90 millimeters of mercury (mmHg) or diastolic of less than 60 mmHg is generally considered to be hypotension. (wikipedia.org)
  • The Hypotension Prediction Index alarm started 3.0 [1.0 to 8.9] min before hypotension occurred, with a concurrent MAP of 71 [70 to 73] mmHg. (anesthesiaexperts.com)
  • When a Hypotension Prediction Index alarm was present, the MAP was 75 mmHg or less 94% of the time. (anesthesiaexperts.com)
  • When a threshold of MAP 70 mmHg or less was chosen, 98% of the time a Hypotension Prediction Index alarm was also present. (anesthesiaexperts.com)
  • He also experienced hypotension and acute renal failure. (cdc.gov)
  • Some studies address the value of HRV as a predictor of hypotension following subarachnoid anesthesia, mainly using linear methods in the frequency domain. (bvsalud.org)
  • In September, La Jolla Pharmaceutical Co. (NASDAQ:LJPC) reported additional data from the Phase III ATHOS-3 trial of LJPC-501 (angiotensin II) to treat hypotension in adults with distributive or vasodilatory shock who remain hypotensive despite fluid and vasopressor therapy. (biocentury.com)
  • The fundamental GI lesion appears to be increased permeability of the small blood vessels, leading to fluid loss and hypotension. (cdc.gov)
  • Chronic use of alpha blockers or beta blockers can lead to hypotension. (wikipedia.org)
  • The maximum cross-correlation coefficient between MAP and Hypotension Prediction Index signals is -0.91 ± 0.04, with the relationship being negative due to the inverted trend mentioned ( fig. 2 ). (anesthesiaexperts.com)
  • Some trials excluded adults with low standing systolic BP, limiting the number of participants with standing hypotension. (medscape.com)
  • Reduced blood volume, hypovolemia, is the most common cause of hypotension. (wikipedia.org)
  • A single session of exercise can induce hypotension and water-based exercise can induce a hypotensive response. (wikipedia.org)
  • Hypotension is the opposite of hypertension, which is high blood pressure. (wikipedia.org)
  • Hypotension was virtually eliminated by use of high-dose prophylactic phenylephrine infusion at a rate of 100 µg/min and rapid crystalloid coload up to two liters (administration at the time of SA). (veeva.com)
  • The aim of the study was to compare the efficacy of dexmedetomidine against propofol infusion when used for controlled hypotension during FESS. (bvsalud.org)
  • It most often occurs when blood pressure is too low (hypotension) and the heart doesn't pump enough oxygen to the brain. (santripty.com)
  • The bolus administration of phenylephrine to treat hypotension is still commonly used, but requests multiple interventions from the anesthesiologists and is time consuming. (veeva.com)
  • This page shows results related to Beconase and Hypotension from the FDA Adverse Event Reporting System (AERS). (drugcite.com)
  • The recent special article by Enevoldsen and Vistisen focused on the data selection process for the development of this algorithm, highlighting the overrepresentation of the mean arterial pressure (MAP) within the Hypotension Prediction Index as substantiated with simulated data. (anesthesiaexperts.com)