Alveolar-arterial oxygen tension gradient due to diffusion

1963 ◽  
Vol 18 (4) ◽  
pp. 673-680 ◽  
Author(s):  
Norman C. Staub
Keyword(s):  
Time Course ◽  
Arterial Oxygen Tension ◽  
Normal Subjects ◽  
Arterial Oxygen ◽  
Diffusion Resistance ◽  
Pulmonary Capillaries ◽  
Pulmonary Capillary ◽  
Capillary Membrane ◽  
Capillary Blood Volume ◽  
Pulmonary Capillary Blood

This is a theoretical paper in which the absolute time course of O2 uptake by the red blood cells during their passage through the pulmonary capillaries is calculated from recently obtained values of thetaO2 (the rate of O2 uptake by human red cells per milliliter of blood as a function of O2Hb saturation), the components of diffusion resistance (alveolar-capillary membrane and instantaneous pulmonary capillary blood volume), and the pulmonary blood flow. One result of these calculations is the alveolar-arterial Po2 difference due to diffusion. Five situations of varying degrees of diffusion stress are examined. The diffusion gradient for O2 is generally smaller than that computed by older techniques. Most of the diffusion resistance lies in the blood in normal subjects at rest breathing air. If the membrane and blood components of the diffusion resistance are unevenly distributed in the lung, the diffusion gradient will be greater than the ideal values. Regional variations in capillary transit time for any reason are more serious than membrane variation because of higher diffusion resistance of the blood normally. Submitted on November 19, 1962

Erythrocyte and polymorphonuclear cell transit time and concentration in human pulmonary capillaries

1994 ◽  
Vol 77 (4) ◽  
pp. 1795-1800 ◽  
Author(s):  
J. C. Hogg ◽  
H. O. Coxson ◽  
M. L. Brumwell ◽  
N. Beyers ◽  
C. M. Doerschuk ◽  
...  
Keyword(s):  
Blood Flow ◽  
Regional Blood Flow ◽  
Lung Resection ◽  
Capillary Blood ◽  
Lung Sample ◽  
Pulmonary Capillaries ◽  
Transit Times ◽  
Pulmonary Capillary ◽  
Capillary Blood Volume ◽  
Pulmonary Capillary Blood

Pulmonary capillary transit times were examined in patients who required lung resection by use of 99mTc-labeled macroaggregates (99Tc-MAA) and chromium-labeled erythrocytes (51Cr-RBC) to measure regional blood flow and volume in the resected lung. Cell flow (cells.ml-1.s-1) to each resected lung sample was determined by multiplying the number of polymorphonuclear leukocytes (PMN) per milliliter of circulating blood by the blood flow to that sample. Capillary blood volume was obtained by multiplying the morphometrically determined fraction of pulmonary blood in capillaries by the total 51Cr-RBC volume in each sample. Cell concentrations (cells/ml) in capillary blood were calculated morphometrically, and capillary transit times were obtained by dividing cell concentration by cell flow. The results show that PMN transit times were 60–100 times longer than the RBC transit times, with a 22% overlap between their distributions. We conclude that PMN are concentrated with respect to RBC in pulmonary capillary blood because of differences in their transit times and that these long transit times provide an opportunity for PMN-endothelial interactions.

Effect of prolonged recombency on pulmonary blood volume in normal humans

1981 ◽  
Vol 50 (5) ◽  
pp. 950-955 ◽  
Author(s):  
J. D. Hirasuna ◽  
A. B. Gorin
Keyword(s):  
Blood Volume ◽  
Normal Subjects ◽  
Initial Increase ◽  
Pulmonary Blood Volume ◽  
Single Breath ◽  
Pulmonary Capillary ◽  
Capillary Blood Volume ◽  
Pulmonary Capillary Blood ◽  
Normal Humans ◽  
Pulmonary Capillary Blood Volume

We have observed a progressive decrease in pulmonary blood volume during sustained recumbency measured using two independent methods. Pulmonary capillary blood volume (Vc) was estimated by the method of Roughton and Forster (J. Appl. Physiol. 11: 290, 1957). We measured regional pulmonary blood volume (PBVR) using 99mTc-labeled erythrocytes (Gorin et al., J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 45: 225, 1978). In 21 studies in 19 normal subjects, we measured pulmonary CO diffusing capacity by the single-breath technique and calculated Vc with the subjects seated and at fixed times after lying down. After 5 min in the recumbent position, there was a mean 49% increase in Vc over the value in the seated position. With sustained recumbency Vc decreased 18.3%/h over 90 min. In 12 studies in 8 normal subjects, PBVR declined 16.7%/h with prolonged recumbency in studies lasting 60-90 min. The initial increase in Vc after subjects assumed a supine position has been well described. The subsequent fall in pulmonary blood volume to levels equal to or below that measured with the subject seated has not previously been reported.

Effect of hemodilution on ventilatory fluctuations of pulmonary capillary blood volume

1988 ◽  
Vol 65 (6) ◽  
pp. 2571-2578 ◽  
Author(s):  
J. S. Lee ◽  
L. P. Lee
Keyword(s):  
Blood Volume ◽  
Capillary Blood ◽  
Positive Pressure ◽  
Blood Flows ◽  
Pulmonary Capillaries ◽  
Pulmonary Capillary ◽  
Capillary Blood Volume ◽  
Pulmonary Capillary Blood ◽  
Pulmonary Capillary Blood Volume ◽  
Central Circulation

By diluting the hematocrit (Ha) in the rabbit's circulation without changing its blood volume, we found that the ventilatory-induced fluctuation (delta rho) in the density of aortic blood and Ha (which was in the range of 8-39%) are related by this linear regression: delta rho = 0.63 g/l (-0.009 + Ha). In this hemodilution experiment, the rabbits were ventilated by an intermittent positive pressure of 6 mmHg at a frequency of 30-35 cycles/min. Based on the Fahraeus effect for capillary blood flows and the dispersion of the density indicator in the rabbit's central circulation, we computed from the fluctuation of the measured density within a ventilation cycle the fluctuation of pulmonary capillary blood volume and found it to be 4.1 +/- 0.4% of the capillary blood volume for all hematocrits. Since the same fluctuation in the airway pressure was used to induce the volumetric fluctuation, its independence of Ha indicates that the hemodilution has no effect on the viscoelasticity of pulmonary capillaries.

Pulmonary diffusing capacity in man during immersion in water

1965 ◽  
Vol 20 (5) ◽  
pp. 878-881 ◽  
Author(s):  
A. R. Guyatt ◽  
Faith Newman ◽  
F. F. Cinkotai ◽  
J. I. Palmer ◽  
M. L. Thomson
Keyword(s):  
Pressure Gauge ◽  
Normal Subjects ◽  
External Pressure ◽  
Capillary Blood ◽  
Diffusing Capacity ◽  
Intermediate Depth ◽  
Pulmonary Capillary ◽  
Capillary Blood Volume ◽  
Pulmonary Capillary Blood ◽  
Pulmonary Capillary Blood Volume

During immersion in water to the neck, seven seated resting normal subjects showed, without exception in 14 trials, an increase in diffusing capacity of the lung (DlCO) which averaged 16.2 ± 0.79 sd % of the control (unimmersed) values (P < 0.001). At an intermediate depth of immersion at which the calculated hydrostatic pressure (gauge) was approximately halved, the rise in DlCO was also halved. The hemodynamic readjustment to external pressure was completed within a few minutes, since no further change in DlCO occurred during continuous immersion to the neck for as long as 90 min. Immersion produced a rise in “permeability” of the lung (Kco) which was on the average 5.8% greater than that in DlCO. In three subjects the pulmonary capillary blood volume (Vc) rose on the average 47% at the deeper level of immersion, suggesting that, as in the pressure suit, the rise in DlCO was due to pulmonary vascular engorgement. pulmonary vascular engorgement Submitted on July 6, 1964

Pulmonary diffusing capacity of athletes

1963 ◽  
Vol 18 (4) ◽  
pp. 687-695 ◽  
Author(s):  
E. M. Mostyn ◽  
S. Helle ◽  
J. B. L. Gee ◽  
L. G. Bentivoglio ◽  
D. V. Bates
Keyword(s):  
Steady State ◽  
Normal Subjects ◽  
Membrane Diffusion ◽  
Distance Runners ◽  
Long Distance ◽  
Pulmonary Capillary ◽  
Capillary Blood Volume ◽  
Pulmonary Capillary Blood ◽  
Pulmonary Capillary Blood Volume ◽  
Predicted Values

Champion swimmers have been found to have significantly higher steady-state pulmonary diffusing capacities than those measured in normal subjects of comparable age at the same exercise level. Nonactive and moderately active normal subjects, swimmers of average ability, long distance runners, and older ex-athletes were found to show no significant deviation from predicted values of DlCO, either in absolute terms or in relation to body surface area or lung midcapacity. The high DlCO in champion swimmers results from a larger than normal pulmonary capillary blood volume (Vc). It has been observed that normal subjects can increase the measured steady-state Dl during exercise by a “held inspiration“ maneuver, but this increase is caused by an increased membrane diffusion component (Dm) per liter midcapacity and not by an increased Vc. Champion swimmers have a particular need of a high Dl since they must be able to transfer large volumes of oxygen across the lung when the alveolar pO2 has fallen to low levels. Submitted on August 20, 1962

Effect of Thrombolytic Therapy on Pulmonary-Capillary Blood Volume in Patients with Pulmonary Embolism

1980 ◽  
Vol 303 (15) ◽  
pp. 842-845 ◽  
Author(s):  
G. V. R. K. Sharma ◽  
Virginia A. Burleson ◽  
Arthur A. Sasahara ◽  
Barbara Roggeveen ◽  
Nazarene Mondello ◽  
...  
Keyword(s):  
Pulmonary Embolism ◽  
Thrombolytic Therapy ◽  
Blood Volume ◽  
Capillary Blood ◽  
Pulmonary Capillary ◽  
Capillary Blood Volume ◽  
Pulmonary Capillary Blood ◽  
Pulmonary Capillary Blood Volume
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