Oxygen-induced alteration of ventilation-perfusion relationships in rats

1979 ◽  
Vol 47 (5) ◽  
pp. 1112-1117 ◽  
Author(s):  
W. E. Truog ◽  
M. P. Hlastala ◽  
T. A. Standaert ◽  
H. P. McKenna ◽  
W. A. Hodson
Keyword(s):  
Gas Exchange ◽  
Pulmonary Gas Exchange ◽  
Inert Gas ◽  
Base Line ◽  
Small Animals ◽  
Difference Curve ◽  
Oxygen Breathing ◽  
Anesthetized Rats ◽  
Effect Of Oxygen ◽  
Breathing Room

The effect of oxygen breathing on shunt and ventilation-perfusion ratios (VA/Q) in anesthetized rats was studied using a modification of the multiple inert gas elimination technique. Base-line analyses showed hypoxemia in some animals breathing room air (arterial O2 tensions 48-70 Torr) associated with intrapulmonary shunts ranging from 0 to 22%, and variable low VA/Q lung regions as determined by calculation of the inert gas arterial-alveolar difference curve. Of nine rats that breathed 100% oxygen for 30 min, three showed increases in shunt (0% leads to 19%, 1.5% leads to 16%, 11% leads to 40%). These three animals had larger preexisting low VA/Q regions than the six that developed no shunt (0.48 +/- 0.15 vs. 0.17 +/- 0.03 (mean +/- SD); P less than 0.05). These data are compatible with the theory of absorption atelectasis. This study documents the usefulness of the inert gas elimination technique for studying pulmonary gas exchange problems in small animals.

Ventilation-perfusion relationships during induced normovolemic polycythemia in dogs

1988 ◽  
Vol 65 (4) ◽  
pp. 1686-1692 ◽  
Author(s):  
A. A. Balgos ◽  
D. C. Willford ◽  
J. B. West
Keyword(s):  
Gas Exchange ◽  
Blood Gases ◽  
Normal Subjects ◽  
Pulmonary Gas Exchange ◽  
Inert Gas ◽  
Base Line ◽  
Slight Improvement ◽  
Arterial Blood ◽  
The Mean ◽  
Arterial Po2

Previous studies on normal subjects and patients with polycythemia have given conflicting results of the effect of polycythemia on pulmonary gas exchange. We studied acutely induced normovolemic polycythemia in the dog and measured arterial blood gases and ventilation-perfusion (VA/Q) relationships using the multiple inert gas elimination technique. The mean base-line hematocrit of 43 +/- 5% was increased to 57 +/- 4 and 68 +/- 8%, respectively, after two exchange transfusions of packed erythrocytes. Subsequent plasma exchange transfusions returned the mean hematocrit to 44 +/- 4%. Polycythemia caused no significant arterial hypoxemia; indeed there was a slight improvement in the alveolar-arterial PO2 difference. The multiple inert gas elimination measurements showed no increase in VA/Q inhomogeneity with no increase in log SD ventilation (V) or log SD blood flow (Q). There was a shift of mean V and mean Q to high VA/Q areas because of a decrease in cardiac output, presumably caused by increased blood viscosity. This study showed no deleterious effects on pulmonary gas exchange within the hematocrit range of 36-76%.

Pulmonary gas exchange efficiency during exercise breathing normoxic and hypoxic gas in adults born very preterm with low diffusion capacity

2014 ◽  
Vol 117 (5) ◽  
pp. 473-481 ◽  
Author(s):  
Joseph W. Duke ◽  
Jonathan E. Elliott ◽  
Steven S. Laurie ◽  
Kara M. Beasley ◽  
Tyler S. Mangum ◽  
...  
Keyword(s):  
Preterm Birth ◽  
Gas Exchange ◽  
Pulmonary Function ◽  
Pulmonary Gas Exchange ◽  
Peak Oxygen Consumption ◽  
Diffusion Capacity ◽  
Very Preterm ◽  
Arterial Blood ◽  
Very Preterm Birth ◽  
Breathing Room

Adults with a history of very preterm birth (<32 wk gestational age; PRET) have reduced lung function and significantly lower lung diffusion capacity for carbon monoxide (DLCO) relative to individuals born at term (CONT). Low DLCO may predispose PRET to diffusion limitation during exercise, particularly while breathing hypoxic gas because of a reduced O2 driving gradient and pulmonary capillary transit time. We hypothesized that PRET would have significantly worse pulmonary gas exchange efficiency [i.e., increased alveolar-to-arterial Po2 difference (AaDO2)] during exercise breathing room air or hypoxic gas (FiO2 = 0.12) compared with CONT. To test this hypothesis, we compared the AaDO2 in PRET ( n = 13) with a clinically mild reduction in DLCO (72 ± 7% of predicted) and CONT ( n = 14) with normal DLCO (105 ± 10% of predicted) pre- and during exercise breathing room air and hypoxic gas. Measurements of temperature-corrected arterial blood gases, and direct measure of O2 saturation (SaO2), were made prior to and during exercise at 25, 50, and 75% of peak oxygen consumption (V̇o2peak) while breathing room air and hypoxic gas. In addition to DLCO, pulmonary function and exercise capacity were significantly less in PRET. Despite PRET having low DLCO, no differences were observed in the AaDO2 or SaO2 pre- or during exercise breathing room air or hypoxic gas compared with CONT. Although our findings were unexpected, we conclude that reduced pulmonary function and low DLCO resulting from very preterm birth does not cause a measureable reduction in pulmonary gas exchange efficiency.

Pulmonary gas exchange during exercise in athletes. I. Ventilation-perfusion mismatch and diffusion limitation

1994 ◽  
Vol 77 (2) ◽  
pp. 912-917 ◽  
Author(s):  
S. R. Hopkins ◽  
D. C. McKenzie ◽  
R. B. Schoene ◽  
R. W. Glenny ◽  
H. T. Robertson
Keyword(s):  
Gas Exchange ◽  
Aerobic Capacity ◽  
Maximal Exercise ◽  
Cycle Ergometer ◽  
Pulmonary Gas Exchange ◽  
Inert Gases ◽  
Inert Gas ◽  
Diffusion Limitation ◽  
Maximal Aerobic Capacity ◽  
Arterial Blood

To investigate pulmonary gas exchange during exercise in athletes, 10 high aerobic capacity athletes (maximal aerobic capacity = 5.15 +/- 0.52 l/min) underwent testing on a cycle ergometer at rest, 150 W, 300 W, and maximal exercise (372 +/- 22 W) while trace amounts of six inert gases were infused intravenously. Arterial blood samples, mixed expired gas samples, and metabolic data were obtained. Indexes of ventilation-perfusion (VA/Q) mismatch were calculated by the multiple inert gas elimination technique. The alveolar-arterial difference for O2 (AaDO2) was predicted from the inert gas model on the basis of the calculated VA/Q mismatch. VA/Q heterogeneity increased significantly with exercise and was predicted to increase the AaDO2 by > 17 Torr during heavy and maximal exercise. The observed AaDO2 increased significantly more than that predicted by the inert gas technique during maximal exercise (10 +/- 10 Torr). These data suggest that this population develops diffusion limitation during maximal exercise, but VA/Q mismatch is the most important contributor (> 60%) to the wide AaDO2 observed.

Reproduction of inert gas and oxygenation data: a comparison of the MIGET and a simple model of pulmonary gas exchange

2010 ◽  
Vol 36 (12) ◽  
pp. 2117-2124 ◽  
Author(s):  
Stephen E. Rees ◽  
S. Kjærgaard ◽  
S. Andreassen ◽  
G. Hedenstierna
Keyword(s):  
Simple Model ◽  
Gas Exchange ◽  
Pulmonary Gas Exchange ◽  
Inert Gas

EFFECT OF OXYGEN ON THE REGIONAL DISTRIBUTION OF VENTILATION AND PERFUSION IN THE LUNG

1966 ◽  
Vol 44 (1) ◽  
pp. 89-93 ◽  
Author(s):  
H. S. Holley ◽  
A. Dawson ◽  
A. C. Bryan ◽  
J. Milic-Emili ◽  
D. V. Bates
Keyword(s):  
Regional Distribution ◽  
Healthy Male ◽  
Regional Ventilation ◽  
Oxygen Breathing ◽  
Lower Lung ◽  
Effect Of Oxygen ◽  
Breathing Room ◽  
Male Subjects ◽  
Ventilation And Perfusion ◽  
Measure Distribution

Xenon133 was used to measure distribution of ventilation and perfusion in the upper, middle, and lower lung zones of 12 upright healthy male subjects, at rest and during exercise, while breathing room air and after breathing 100% oxygen for 20 minutes. During the breathing of both air and 100% oxygen, ventilation and perfusion increased from the apex to the base of the lung, the differences between upper and lower zones becoming less pronounced during exercise. Oxygen breathing did not appear to affect distribution of regional ventilation or perfusion in normal upright man, either at rest or during exercise. This negative result is of importance in relation to the possible role in intact man of homeostatic mechanisms of adjusting perfusion and ventilation, which are sensitive to oxygen tension.

Isoflurane and Sevoflurane Anesthesia in Pigs with a Preexistent Gas Exchange Defect

2001 ◽  
Vol 95 (6) ◽  
pp. 1422-1426 ◽  
Author(s):  
Axel Kleinsasser ◽  
Karl H. Lindner ◽  
Christoph Hoermann ◽  
Andreas Schaefer ◽  
Christian Keller ◽  
...  
Keyword(s):  
Blood Flow ◽  
Gas Exchange ◽  
Porcine Model ◽  
Minimum Alveolar Concentration ◽  
Pulmonary Gas Exchange ◽  
Inert Gas ◽  
Sevoflurane Anesthesia ◽  
Isoflurane Anesthesia ◽  
Volatile Anesthesia ◽  
Normal Ventilation

Background Decreased arterial partial pressure of oxygen (PaO2) during volatile anesthesia is well-known. Halothane has been examined with the multiple inert gas elimination technique and has been shown to alter the distribution of pulmonary blood flow and thus PaO2. The effects of isoflurane and sevoflurane on pulmonary gas exchange remain unknown. The authors hypothesized that sevoflurane with a relatively high minimum alveolar concentration (MAC) would result in significantly more gas exchange disturbances in comparison with isoflurane or control. Methods This study was performed in a porcine model with an air pneumoperitoneum that generates a reproducible gas exchange defect. After a baseline measurement of pulmonary gas exchange (multiple inert gas elimination technique) during propofol anesthesia, 21 pigs were randomly assigned to three groups of seven animals each. One group received isoflurane anesthesia, one group received sevoflurane anesthesia, and one group was continued on propofol anesthesia (control). After 30 min of volatile anesthesia at 1 MAC or propofol anesthesia, a second measurement (multiple inert gas elimination technique) was performed. Results At the second measurement, inert gas shunt was 15 +/- 3% (mean +/- SD) during sevoflurane anesthesia versus 9 +/- 1% during propofol anesthesia (P = 0.02). Blood flow to normal ventilation/perfusion (V(A)/Q) lung areas was 83 +/- 5% during sevoflurane anesthesia versus 89 +/- 1% during propofol anesthesia (P = 0.04). This resulted in a PaO2 of 88 +/- 11 mmHg during sevoflurane anesthesia versus 102 +/- 15 mmHg during propofol anesthesia (P = 0.04). Inert gas and blood gas variables during isoflurane anesthesia did not differ significantly from those obtained during propofol anesthesia. Conclusions In pigs with an already existent gas exchange defect, sevoflurane anesthesia but not isoflurane anesthesia causes significantly more gas exchange disturbances than propofol anesthesia does.

Multiple inert gas elimination technique

1984 ◽  
Vol 56 (1) ◽  
pp. 1-7 ◽  
Author(s):  
M. P. Hlastala
Keyword(s):  
Gas Exchange ◽  
Mathematical Models ◽  
Dead Space ◽  
Experimental Error ◽  
General Pattern ◽  
Pulmonary Gas Exchange ◽  
Inert Gases ◽  
Inert Gas ◽  
Biological Phenomena ◽  
Mixed Venous

The understanding of pulmonary gas exchange has undergone several major advances since the early 1900‣s. One of the most significant was the development of the multiple inert gas elimination technique for assessing the ventilation-perfusion (VA/Q) distribution in the lung. By measuring the mixed venous, arterial, and mixed expired concentrations of six infused inert gases, it is possible to distinguish shunt, dead space, and the general pattern of VA/Q distribution. As with all mathematical models of complex biological phenomena, there are limitations that can result in errors of interpretation if the technique is applied uncritically. In addition, methodological limitations also can lead to both experimental error and errors of interpretation. Despite these limitations, the multiple inert gas elimination technique remains the most powerful tool developed to date to analyze pulmonary gas exchange.

Mechanism of improvement in pulmonary gas exchange during growth in awake piglets

1988 ◽  
Vol 65 (3) ◽  
pp. 1055-1061 ◽  
Author(s):  
P. J. Escourrou ◽  
B. P. Teisseire ◽  
R. A. Herigault ◽  
M. O. Vallez ◽  
A. J. Dupeyrat ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Dead Space ◽  
Pressure Difference ◽  
Age Groups ◽  
Pulmonary Gas Exchange ◽  
Inert Gas ◽  
Diffusion Limitation ◽  
Significant Difference ◽  
Arterial Po2 ◽  
And Diffusion

Previous studies have shown a lower arterial PO2 (PaO2) in infants and young animals than in adults. To investigate the mechanism of this impairment of gas exchange we studied 13 piglets from 12 to 65 days of age. Two days after instrumentation we measured the distribution of ventilation-perfusion ratios (VA/Q) by use of the multiple inert gas technique on awake animals. We showed that PaO2 is lower in young animals, increasing from 72 +/- 11.5 Torr before 2 wk to 102 Torr at 2 mo. This hypoxemia is due to an enlarged alveolar-arterial O2 pressure difference that significantly decreases with age. This impairment in gas exchange is not due to shunting (0.6 +/- 1.3%). Mean dead space (36 +/- 11%) was not related to age. Mean modes of perfusion and ventilation did not differ significantly between age groups. However, the dispersion of perfusion as expressed by its logSD decreased significantly with age, whereas dispersion of ventilation remained constant. Furthermore, in the young animals only, a significant difference was evidenced between measured alveolar-arterial PO2 gradient and the value predicted by the inert gas model. We therefore conclude that the impairment of gas exchange in piglets is due to two mechanisms: VA/Q mismatch and diffusion limitation for O2.

scholarly journals Intra‐pulmonary arteriovenous anastomoses and pulmonary gas exchange: evaluation by microspheres, contrast echocardiography and inert gas elimination

2019 ◽  
Vol 597 (22) ◽  
pp. 5365-5384 ◽  
Author(s):  
Michael K. Stickland ◽  
Vincent Tedjasaputra ◽  
Cameron Seaman ◽  
Desi P. Fuhr ◽  
Sophie É. Collins ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Contrast Echocardiography ◽  
Pulmonary Gas Exchange ◽  
Inert Gas ◽  
Arteriovenous Anastomoses
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