• venous blood
  • The multiple inert gas elimination technique (MIGET) is a medical technique used mainly in pulmonology that involves measuring the concentrations of various infused, inert gases in mixed venous blood, arterial blood, and expired gas of a subject. (wikipedia.org)
  • It measures the changing absorbance at each of the wavelengths, allowing it to determine the absorbances due to the pulsing arterial blood alone, excluding venous blood, skin, bone, muscle, fat, and (in most cases) nail polish. (wikipedia.org)
  • Vasodilation and pooling of venous blood in the head due to compromised venous return to the heart can cause a combination of arterial and venous pulsations in the forehead region and lead to spurious SpO2 results. (wikipedia.org)
  • alveoli
  • At the dependent region smaller volumes mean the alveoli are more compliant (more distensible) and so capable of wider oxygen exchanges with the external environment. (wikipedia.org)
  • What happens to blood oxygen content and pressure values as blood passing normal and blocked alveoli mixes? (cram.com)
  • Contusion involves hemorrhage in the alveoli (tiny air-filled sacs responsible for absorbing oxygen), but a hematoma is a discrete clot of blood not interspersed with lung tissue. (wikipedia.org)
  • In other words, the ventilation/perfusion ratio (the ratio of air reaching the alveoli to blood perfusing them) is zero. (wikipedia.org)
  • The rest of the difference is due to the continual uptake of oxygen by the pulmonary capillaries, and the continual diffusion of CO2 out of the capillaries into the alveoli. (wikipedia.org)
  • lungs
  • So where is the VQ ratio highest in the lungs? (cram.com)
  • Why does emphysema result in an abnormal VQ ratio in the lungs? (cram.com)
  • Because in the lungs, you're at the top of the oxygen dissociation curve, where changes in blood oxygen content don't change PO2 much. (cram.com)
  • The process might initially seem counterintuitive, as low oxygen levels might theoretically stimulate increased blood flow to the lungs to increase gas exchange. (wikipedia.org)
  • The V/Q ratio of a healthy lung is approximately equal to 0.8, as normal lungs are not perfectly matched. (wikipedia.org)
  • Let us consider some scenarios where there is a defect in ventilation and/ or perfusion of the lungs. (wikipedia.org)
  • In cases of right to left shunts more of deoxygenated blood mixes with oxygenated blood from the lungs and thus to a small extent the condition might neutralize the high A-a gradient with pure oxygen therapy. (wikipedia.org)
  • capillary
  • The gradients across the arterial segment (Pa = Ppa - Pc) and across the venous segment (Pv = Pc - Pw) of the pulmonary vasculature were defined by the computation of effective capillary pressure (Pc) obtained from the analysis of the transient decay of pulmonary artery pressure (Ppa) toward wedge pressure (Pw) after arterial occlusion. (uliege.be)
  • diastolic
  • While the presence of a coronary circulation in certain fishes decreases the reliance of the heart on P v O 2 , hypoxic bradycardia could still benefit oxygen delivery via an extended diastolic period during which peak coronary blood flow occurs. (biologists.org)
  • Due to the structural and functional characteristics of the right ventricle (thin walled chamber with low pressure, low oxygen demand and both systolic and diastolic perfusion), it is unusual to have a massive extension of the infarction and an irreversible progress. (biomedsearch.com)
  • decreases
  • Hyperventilation exists when the same ratio decreases - less than 35mmHg. (wikipedia.org)
  • As altitude increases, the available amount of oxygen to sustain mental and physical alertness decreases with the overall air pressure, though the relative percentage of oxygen in air, at about 21%, remains practically unchanged up to 21,000 metres (70,000 ft). (wikipedia.org)
  • inhalation
  • Bindslev L, Hedenstierna G, Santesson J, Gottlieb I and Carvallhas A.: Ventialtion-perfusion distribution during inhalation anaesthesia. (springer.com)
  • increases
  • Thus, either ventilation (V) remains stable or even becomes more variable, V/Q heterogeneity increases at increased Qt. (omicsonline.org)
  • Six group E dogs were infused with endotoxin at a rate of 0.25 microgram/kg min, while six additional animals served as control (group C). Endotoxin induced increases in flow resistance from 0.056 to 0.096 mm Hg/ml/min/kg due to arterial vasoconstriction and increases in critical closure from 2.3 to 8.4 mm Hg due to a venous waterfall. (uliege.be)
  • blood oxygen
  • This has a major impact on the V/Q ratio: apex of lung - higher base of lung - lower In a subject standing in orthostatic position (upright) the apex of the lung shows higher V/Q ratio, while at the base of the lung the ratio is lower but nearer to the optimal value for reaching adequate blood oxygen concentrations. (wikipedia.org)
  • Signs of a PE include low blood oxygen levels, rapid breathing, rapid heart rate, and sometimes a mild fever. (wikipedia.org)
  • dissociation curve
  • In contrary, the simultaneously created higher V/Q units cannot mitigate these adverse changes because of the sigmoid shape of hemoglobin oxygen dissociation curve. (omicsonline.org)
  • nitric oxide
  • A particularly important intermediate in the chemical industry, nitric oxide forms in mixtures of nitrogen and oxygen at high temperatures, as found in combustion systems such as internal-combustion piston engines, gas turbines, furnaces, and boilers. (wikipedia.org)
  • When exposed to oxygen, nitric oxide is converted into nitrogen dioxide. (wikipedia.org)
  • In water, nitric oxide reacts with oxygen and water to form HNO2 or nitrous acid. (wikipedia.org)
  • The nitric oxide reacts with the ozone to produce oxygen and nitrogen dioxide, accompanied with emission of light (chemiluminescence): ·NO + O3 → NO2 + O2 + hν which can be measured with a photodetector. (wikipedia.org)
  • occurs
  • Energy needed to perform short lasting, high intensity bursts of activity is derived from anaerobic metabolism within the cytosol of muscle cells, as opposed to aerobic respiration which utilizes oxygen, is sustainable, and occurs in the mitochondria. (wikipedia.org)
  • The RMS velocities of diatomic nitrogen and oxygen are very similar and thus no change occurs in the ratio of oxygen to nitrogen until stratospheric heights. (wikipedia.org)
  • pressure
  • Gravity and lung's weight act on ventilation by increasing pleural pressure at the base (making it less negative) and thus reducing the alveolar volume. (wikipedia.org)
  • The apex, though showing a higher oxygen partial pressure, ventilates less efficiently since its compliance is lower and so smaller volumes are exchanged. (wikipedia.org)
  • The impact of gravity on pulmonary perfusion expresses itself as the hydrostatic pressure of the blood passing through the branches of the pulmonary artery in order to reach the apical and basal district of the lung, acting respectively against or synergistically with the pressure developed by the right ventricle. (wikipedia.org)
  • To achieve this goal, multipoint plots of total pressure gradient, arterial pressure gradient, and venous pressure gradient vs. flow were generated by graded inflation of a right atrial balloon, which was used to vary flow. (uliege.be)
  • This infusion produced a minor, nonsignificant change in the intercept of arterial pressure gradient vs. flow, whereas it increased its slope significantly (p less than .05) from 0.036 to 0.081 mm Hg/mL/min/kg. (uliege.be)
  • These endotoxin-induced effects consisted of increased vascular resistance of the arterial segment and appearance of a Starling resistor at the venous side of the pulmonary circulation, which acted as the relevant back-pressure to flow. (uliege.be)
  • Redistribution of pulmonary blood flow in the dog with positive end-expiratory pressure Ventilation. (springer.com)
  • patients
  • In all patients arterial O 2 - and CO 2 -tensions as well as pH and standard bicarbonate were determined. (springer.com)
  • In 18 of these patients the same measurements were carried out after breathing 99% oxygen. (springer.com)