Left ventricular dynamics of trained dogs anesthetized with methohexital.
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The cardiac response to intravenous administration of the ultrashort-acting oxybarbiturate anesthetic, methohexital sodium, was studied in trained dogs. Heart rate increased immediately and gradually declined to the control value 60 minutes later. Stroke volume decreased immediately, reversed transiently, and decreased again, to return gradually to the control value at one hour. Peak aortic flow velocity and peak aortic flow acceleration paralleled the triphasic response of stroke volume. Cardiac output decreased initially, then increased to above the control value to a maximum at the time of maximum heart rate, then decreased again to below the control value by 30 minutes. From 30 minutes to 60 minutes cardiac output gradually returned to the control value. (+info)
Hemodynamic and ventilatory responses to fentanyl, fentanyl-droperidol, and nitrous oxide in patients with acquired valvular heart disease.
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Fentanyl (10 mug/kh) or fentanyl (10 mug/kg) plus droperidol (100 mug/kg) administered intravenously during 20 minutes to adult patients with acquired valvular heart disease produced minimal circulatory changes. The trend during drug infusion was for mean arterial pressure and systemic vascular resistance to decrease, and for cardiac index and stroke volume index to increase without change in heart rate. Central venous pressure increased during drug infusion (P less than 0.05) but decreased to awake levels following controlled ventilation and skeletal-muscle paralysis, probably reflecting thoracoabdominal-muscle rigidity rather than a circulatory response. Hypoventilation during drug infusion necessitated assisted or controlled ventilation, with or without skeletal muscle paralysis, in 14 of 16 patients. Addition of 60 per cent nitrous oxide following fentanyl or fentanyl-droperidol infusion significantly decreased mean arterial pressure, heart rate, and cardiac index. All circulatory changes were similar in direction and extent to those previously found during morphine-nitrous oxide anesthesia. (Key words: Anesthetics, intravenous, fentanyl; Anesthetics, gases, nitrous oxide; Heart, effect of fentanyl, dorperidol, and nitrous oxide.). (+info)
Assessment of depth of anesthesia and postoperative respiratory recovery after remifentanil- versus alfentanil-based total intravenous anesthesia in patients undergoing ear-nose-throat surgery.
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BACKGROUND: The authors investigated whether total intravenous anesthesia (TIVA) with precalculated equipotent infusion schemes for remifentanil and alfentanil would ensure appropriate analgesia and that remifentanil would result in better recovery characteristics. METHODS: Forty consenting patients (classified as American Society of Anesthesiologists physical status I-III) scheduled for microlaryngoscopy were randomized to receive, in a double-blind manner, either remifentanil (loading dose 1 microg/kg; maintenance infusion, 0.25 microg x kg(-1) x min-1) or alfentanil (loading dose, 50 microg/kg; maintenance infusion, 1 microg x kg(-1) x min-1) as the analgesic component of TIVA. They were combined with propofol (loading dose, 2 mg/kg; maintenance infusion, 100 microg x kg(-1) min(-1)). To insure an equal state of anesthesia, the opioids were titrated to maintain heart rate and mean arterial pressure within 20% of baseline, and propofol was titrated to keep the bispectral index (BIS) less than 60. Neuromuscular blockade was achieved with succinylcholine. Drug dosages and the times from cessation of anesthesia to extubation, verbal response, recovery of ventilation, and neuropsychological testing, orientation, and discharge readiness were recorded. RESULTS: Demographics, duration of surgery, and anesthesia were similar between the two groups. Both groups received similar propofol doses. There were no difference in BIS values preoperatively (mean, 96), intraoperatively (mean, 55), and postoperatively (mean, 96). Recovery of BIS and times for verbal response did not differ. At 20, 30, and 40 min after terminating the opioid infusion, the peripheral oxygen saturation and respiratory rate were significantly higher in the remifentanil group compared with the alfentanil group. CONCLUSIONS: When both the hypnotic and analgesic components of a TIVA-based anesthetic are administered in equipotent doses, remifentanil provides a more rapid respiratory recovery, even after brief surgical procedures, compared with alfentanil. (+info)
Myocardial metabolism during pentobarbital anesthesia in dogs.
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Myocardial substrate utilization and hemodynamics were determined in dogs before and one hour and two hours after intravenous administration of sodium pentobarbital. Although total body O2 consumption decreased, along with arterial O2 concentration, there was no significant change in mean arterial pressure or cardiac output. Arterial free fatty acid (FFA) concentration and myocardial FFA remained the major energy source for the heart. Arterial glucose concentrations decreased significantly after pentobarbital, but myocardial uptake of glucose remained unchanged. Neither arterial lactic acid concentration nor myocardial lactate uptake was affected. Mocardial pyruvate uptake, by contrast, while remaining quantitatively the least of the contributors of energy measured, was more than double one hour after pentobarbital injection despite the fact that arterial pyruvate concentration did not increase. It is concluded that pentobarbital reduces the FFA utilization of both the whole animal and of its myocardium. The energy consumption of the whole animal is similarly diminished, whereas the energy used by myocardium is unchanged, other substrates evidently being substituted for FFA as energy sources. (+info)
Total intravenous anaesthesia with methohexitone or propofol for knee arthroscopy in day-case surgery.
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The aim of the study was to assess the usefulness of methohexitone and propofol in total intravenous anaesthesia applied during planned knee joint arthroscopy in day-case surgery. Studies comprised 186 patients divided into 2 groups depending on the anaesthetic used (methohexitone n = 112 or propofol n = 74). ECG, heart rate, systolic and diastolic blood pressure and blood saturation using pulsoxymetry were monitored during anaesthesia. The time of regaining consciousness was measured and the orientation test was performed 5 and 10 minutes after regaining consciousness. Our results and observations confirm that total intravenous anaesthesia is useful in day-case surgery for knee joint arthroscopy. Both methohexitone and propofol cause cardiac and respiratory depression. Patients on propofol regain psychomotoric efficiency earlier then patients who received methohexitone. (+info)
Ocular effects of diacetyl morphine and lysergic acid diethylamide in rabbit.
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Intravenous lysergic acid diethylamide (LSD) given to rabbits in doses from 1 to 100 mug per kilogram of body weight produced a dose-related increase in intraocular pressure and outflow facility. Minor changes in systemic blood pressure were observed, but respiration rate was accelerated, and mydriasis became pronounced at higher doses. Diacetyl morphine (heroin) was given intravenously in doses from 0.1 to 2 mg. per kilogram of body weight. A dose-related decrease in intraocular pressure and an increase in outflow facility was found. A dose-related miosis was observed and at higher doses respiration became markedly depressed. Neither drug alters the permeability of the isolated ciliary epithelium. Both drugs appear to increase capillary blood pressure and, hence, aqueous humor inflow to cause the intraocular pressure to be maintained at approximately normal levels in face of increases in outflow facility of 50 per cent. (+info)
Anesthesia of bulls undergoing surgical manipulation of the vas deferentia.
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Twelve bulls ranging from 341 to 545 kilograms in body mass were successfully anesthetized for either vasectomy or prosthetic vas deferens implantation with a combination of thiopental sodium, glyceryl guaiacolate, nitrous oxide, halothane and oxygen. Duration of anesthetic administration was 119.2 plus or minus 24.2 (S.D.) minutes. Righting reflexes returned 15.0 plus or minus 8.0 minutes after cessation of anesthetic administration and the bulls were capable of standing within 46.6 plus or minus 17.8 minutes. Interpretations of pulse rate, respiratory rate and eye reflexes were related to anesthetic depth and maintenance. A control mean respiratory frequency of 28.8 plus or minus 3.6 per minute compared to minimum and maximum frequencies of 26.8 plus or minus 5.1 and 37.6 plus or minus 6.3, respectively, during anesthetic maintenance. A control mean pulse frequency of 91.6 plus or minus 15.9 per minute compared to minimum and maximum frequencies of 84.8 plus or minus 13 and 102.3 plus or minus 13.4, respectively, during maintenance of anesthesia. Methods for avoiding complications related to anesthetic induction, maintenance and emergence were described. Specific pharmacological aspects of atropine, halothane and nitrous oxide were emphasized in light of their application to ruminant anesthesia. (+info)
Aspects of bile secretion in the rabbit.
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1. Bile secretion was studied in anaesthetized rabbits from whom hepatic bile was collected by cannulation of the common bile duct. 2. The flow and composition of bile formed by rabbits anaesthetized with urethane differed significantly from that formed by rabbits anaesthetized with pentobarbitone sodium. 3. The I.P. injection of a hypertonic solution of sucrose (3 M) decreased bile flow and produced changes in the ionic composition of bile and of plasma. 4. The infusion of sodium taurodeoxycholate (1-5-20 mumole/min I.V.) gave higher rates of bile flow than did equimolar infusions of sodium taurocholate, and unlike taurocholate, increased the bicarbonate concentration of bile. 5. Acetazolamide (10-100 mg/kg) increased the concentration of bicarbonate both in bile and in plasma, and had little effect on bile flow. 6. The infusion of bromsulphthalein (5 mg/kg I.V.) decreased the excretion of bicarbonate into bile, and was associated with the formation of a hypotonic bile. 7. The implications of these results in relation to the mechanisms of bile secretion are discussed. (+info)