Effects of gravity on lung diffusing capacity and cardiac output in prone and supine humans

2003 ◽  
Vol 95 (1) ◽  
pp. 3-10 ◽  
Author(s):  
M. Rohdin ◽  
J. Petersson ◽  
P. Sundblad ◽  
M. Mure ◽  
R. W. Glenny ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Normal Subjects ◽  
Arterial Oxygenation ◽  
Diffusing Capacity ◽  
Alveolar Volume ◽  
Pulmonary Capillary Blood Flow ◽  
Pulmonary Capillary ◽  
Supine Posture ◽  
Pulmonary Capillary Blood ◽  
Residual Capacity

Both in normal subjects exposed to hypergravity and in patients with acute respiratory distress syndrome, there are increased hydrostatic pressure gradients down the lung. Also, both conditions show an impaired arterial oxygenation, which is less severe in the prone than in the supine posture. The aim of this study was to use hypergravity to further investigate the mechanisms behind the differences in arterial oxygenation between the prone and the supine posture. Ten healthy subjects were studied in a human centrifuge while exposed to 1 and 5 times normal gravity (1 G, 5 G) in the anterioposterior (supine) and posterioanterior (prone) direction. They performed one rebreathing maneuver after ∼5 min at each G level and posture. Lung diffusing capacity decreased in hypergravity compared with 1 G (ANOVA, P = 0.002); it decreased by 46% in the supine posture compared with 25% in the prone ( P = 0.01 for supine vs. prone). At the same time, functional residual capacity decreased by 33 and 23%, respectively ( P < 0.001 for supine vs. prone), and cardiac output by 40 and 31% ( P = 0.007 for supine vs. prone), despite an increase in heart rate of 16 and 28% ( P < 0.001 for supine vs. prone), respectively. The finding of a more impaired diffusing capacity in the supine posture compared with the prone at 5 G supports our previous observations of more severe arterial hypoxemia in the supine posture during hypergravity. A reduced pulmonary-capillary blood flow and a reduced estimated alveolar volume can explain most of the reduction in diffusing capacity when supine.

Effects of water immersion to the neck on pulmonary circulation and tissue volume in man

1976 ◽  
Vol 40 (3) ◽  
pp. 293-299 ◽  
Author(s):  
R. Begin ◽  
M. Epstein ◽  
M. A. Sackner ◽  
R. Levinson ◽  
R. Dougherty ◽  
...  
Keyword(s):  
Water Immersion ◽  
Normal Subjects ◽  
Capillary Blood ◽  
Alveolar Volume ◽  
Pulmonary Tissue ◽  
Fourfold Increase ◽  
Pulmonary Capillary Blood Flow ◽  
Capillary Blood Volume ◽  
Pulmonary Capillary Blood ◽  
Residual Capacity

Utilizing the rebreathing of a gas mixture containing C2H2, C180, He O2, and N2, we obtained serial measurements of the pulmonary capillary blood flow (Qc), diffusing capacity per unit of alveolar volume (DL/VA), functional residual capacity (FRC), pulmonary tissue plus capillary blood volume (VTPC), and O2 comsumption (VO2) in five normal subjects under the following conditions: 1) 6 h of sitting, 2) 4 h of sitting while immersed in thermoneutral water to the neck, and 3) 4 h of lying in thermoneutral water to the neck. Water immersion (NI) was preceded and followed by 1-h prestudy and 1-h recovery periods. The measurements were made at 30-min intervals. Seated NI produced a fourfold increase in sodium excretion (UNaV), a 25–36% increase in Qc, a 45–59% increase in DL/VA, and a 30–36% decrease in FRC. This occurred as early as the 1st h of NI and persisted throughout the 4-h period of study. Throughout the seated control and NI periods, VO2, heart rate, and VTPC remained constant. During supine NI, Qc, HR, DL/VA, FRC, and VO2 did not differ significantly from supine prestudy. These date demonstrate that seated NI causes a significant increase of Qc and DL/VA which persists throughout the immersion period. Furthermore, the lack of change of VTPC suggests that the central vascular engorgement induced by seated NI is not accompanied by extravasation of fluid into the pulmonary interstitial space.

Microvascular injury distal to unilateral pulmonary artery occlusion

1981 ◽  
Vol 51 (4) ◽  
pp. 845-851 ◽  
Author(s):  
R. L. Johnson ◽  
S. S. Cassidy ◽  
M. Haynes ◽  
R. L. Reynolds ◽  
W. Schulz
Keyword(s):  
Pulmonary Artery ◽  
Left Lung ◽  
Left Pulmonary Artery ◽  
Artery Occlusion ◽  
Diffusing Capacity ◽  
Pulmonary Capillary Blood Flow ◽  
Pulmonary Capillary ◽  
Pulmonary Capillary Blood ◽  
Rebreathing Method ◽  
Unilateral Pulmonary Artery Occlusion

We explored three questions: 1) does edema fluid accumulate distal to temporary unilateral pulmonary artery occlusion (TUPAO); 2) if so how rapidly does it accumulate; and 3) how is it affected by positive end-expiratory pressure (PEEP)? Using a tracheal divider we measured pulmonary capillary blood flow (Qc), tissue volume (Vt), and diffusing capacity (DLCO) in each lung with a rebreathing method. After control measurements in 12 dogs, the left pulmonary artery was occluded and measurements were repeated at intervals during 4 h of occlusion and 30 min after release of the occlusion. Six of the dogs were ventilated with 10 cmH2O PEEP. Finally the lungs were removed, weighed, and fixed for histology. TUPAO caused a 29% increase in Vt of the left lung without PEEP and a 59% increase with PEEP. After release of the occlusion, Qc and DLCO in the left lung returned to control levels within 30 min in dogs not on PEEP but remained depressed in dogs ventilated with PEEP even though PEEP was removed. At postmortem the left lung weighed more than expected in both groups of dogs but was significantly heavier in those on PEEP. Histology confirmed bronchovascular cuffing with edema and hemorrhage.

Bronchospirometric studies of lung volumes, ventilation/perfusion ratios and diffusion

1965 ◽  
Vol 20 (1) ◽  
pp. 79-86 ◽  
Author(s):  
E. M. Cree ◽  
H. K. Rasmussen ◽  
F. Wright ◽  
J. K. Curtis
Keyword(s):  
Breath Holding ◽  
Physiological Changes ◽  
Diffusing Capacity ◽  
Lung Volumes ◽  
Nitrogen Washout ◽  
Pulmonary Capillary Blood Flow ◽  
Pulmonary Capillary ◽  
Pulmonary Capillary Blood ◽  
First Time ◽  
And Diffusion

Bilateral bronchospirometric nitrogen washout studies were used for the first time to calculate ventilation/perfusion ratios for the well and poorly ventilated areas in individual lungs. Results were compared with washout studies on both lungs measured together. Data suitable for analysis were obtained from seven patients with chronic lung disease. It was demonstrated that this technique for determining simultaneous ventilation/perfusion ratios for each lung gave accurate and detailed physiological changes. Comparison of the sum of average values for pulmonary capillary blood flow when both lungs were measured together by the same nitrogen washout technique showed a variation within the accepted 10% error for cardiac output. Diffusion for the separate lungs, measured by the carbon monoxide breath-holding method, gave values which correlated with lung volumes. bronchospirometry; nitrogen washout; diffusing capacity Submitted on November 22, 1963

scholarly journals Diffusing capacity and pulmonary capillary blood flow at hyperbaric pressures.

1965 ◽  
Vol 44 (10) ◽  
pp. 1591-1599 ◽  
Author(s):  
J R Nairn ◽  
G G Power ◽  
R W Hyde ◽  
R E Forster ◽  
C J Lambertsen ◽  
...  
Keyword(s):  
Blood Flow ◽  
Capillary Blood ◽  
Capillary Blood Flow ◽  
Diffusing Capacity ◽  
Pulmonary Capillary Blood Flow ◽  
Pulmonary Capillary ◽  
Pulmonary Capillary Blood

Effect of pressure-suit inflation on pulmonary-diffusing capacity

1960 ◽  
Vol 15 (5) ◽  
pp. 843-848 ◽  
Author(s):  
Joseph C. Ross ◽  
Thomas H. Lord ◽  
Glen D. Ley
Keyword(s):  
Valsalva Maneuver ◽  
Venous Pressure ◽  
Diffusing Capacity ◽  
Alveolar Volume ◽  
Pulmonary Diffusing Capacity ◽  
Pulmonary Capillary ◽  
Capillary Blood Volume ◽  
Pulmonary Capillary Blood ◽  
Capillary Bed ◽  
Pulmonary Capillary Blood Volume

Pressure-suit inflation over the lower body produces acute pulmonary hypertension. An increase in pulmonary capillary blood volume, Vc, with this procedure should theoretically increase pulmonary-diffusing capacity, Dl. Lewis and co-workers ( J. Appl. Physiol. 12:57, 1958) found no increase in Dl with suit inflation. The subject was reinvestigated with measurement of the increase in central venous pressure, CVP, produced and with a study of effect of alveolar volume, Va, and the Valsalva maneuver on the results. Dl was determined in five seated and seven supine subjects at small and large Va, both before and during suit inflation and also with a Valsalva under each condition. Suit inflation significantly increased Dl (13%) with an increase in 21 of the 22 comparisons. Mean Dl was 16% lower when Va was decreased 34%. The Valsalva maneuver significantly decreased both control and suit inflation Dl. Results show that with controlled Va and no Valsalva and when CVP was definitely increased by the procedure, Dl significantly increased with suit inflation, probably indicating that the pulmonary capillary bed was passively dilated. Submitted on March 11, 1960

scholarly journals High-altitude exposure of three weeks duration increases lung diffusing capacity in humans

2011 ◽  
Vol 110 (6) ◽  
pp. 1564-1571 ◽  
Author(s):  
Piergiuseppe Agostoni ◽  
Erik R. Swenson ◽  
Maurizio Bussotti ◽  
Miriam Revera ◽  
Paolo Meriggi ◽  
...  
Keyword(s):  
High Altitude ◽  
Sea Level ◽  
Diffusing Capacity ◽  
Membrane Diffusion ◽  
Alveolar Volume ◽  
Pulmonary Capillary ◽  
Capillary Blood Volume ◽  
Pulmonary Capillary Blood ◽  
Altitude Adaptation ◽  
Alveolar Capillary

Background: high-altitude adaptation leads to progressive increase in arterial PaO2. In addition to increased ventilation, better arterial oxygenation may reflect improvements in lung gas exchange. Previous investigations reveal alterations at the alveolar-capillary barrier indicative of decreased resistance to gas exchange with prolonged hypoxia adaptation, but how quickly this occurs is unknown. Carbon monoxide lung diffusing capacity and its major determinants, hemoglobin, alveolar volume, pulmonary capillary blood volume, and alveolar-capillary membrane diffusion, have never been examined with early high-altitude adaptation. Methods and Results: lung diffusion was measured in 33 healthy lowlanders at sea level (Milan, Italy) and at Mount Everest South Base Camp (5,400 m) after a 9-day trek and 2-wk residence at 5,400 m. Measurements were adjusted for hemoglobin and inspired oxygen. Subjects with mountain sickness were excluded. After 2 wk at 5,400 m, hemoglobin oxygen saturation increased from 77.2 ± 6.0 to 85.3 ± 3.6%. Compared with sea level, there were increases in hemoglobin, lung diffusing capacity, membrane diffusion, and alveolar volume from 14.2 ± 1.2 to 17.2 ± 1.8 g/dl ( P < 0.01), from 23.6 ± 4.4 to 25.1 ± 5.3 ml·min−1·mmHg−1 ( P < 0.0303), 63 ± 34 to 102 ± 65 ml·min−1·mmHg−1 ( P < 0.01), and 5.6 ± 1.0 to 6.3 ± 1.1 liters ( P < 0.01), respectively. Pulmonary capillary blood volume was unchanged. Membrane diffusion normalized for alveolar volume was 10.9 ± 5.2 at sea level rising to 16.0 ± 9.2 ml·min−1·mmHg−1·l−1 ( P < 0.01) at 5,400 m. Conclusions: at high altitude, lung diffusing capacity improves with acclimatization due to increases of hemoglobin, alveolar volume, and membrane diffusion. Reduction in alveolar-capillary barrier resistance is possibly mediated by an increase of sympathetic tone and can develop in 3 wk.

Effect of lung volume and positional changes on pulmonary diffusing capacity and its components

1991 ◽  
Vol 71 (4) ◽  
pp. 1477-1488 ◽  
Author(s):  
H. Stam ◽  
F. J. Kreuzer ◽  
A. Versprille
Keyword(s):  
Lung Volume ◽  
Supine Position ◽  
Body Position ◽  
Membrane Conductance ◽  
Normal Subjects ◽  
Negative Slope ◽  
Sitting Position ◽  
Diffusing Capacity ◽  
Alveolar Volume ◽  
Residual Capacity

Normal subjects have a larger diffusing capacity normalized per liter alveolar volume (DL/VA) in the supine than in the sitting position. Body position changes total lung diffusing capacity (DL), DL/VA, membrane conductance (Dm), and effective pulmonary capillary blood volume (Qc) as a function of alveolar volume (VA). These functions were studied in 37 healthy volunteers. DL/VA vs. VA yields a linear relationship in sitting as well as in supine position. Both have a negative slope but usually do not run parallel. In normal subjects up to 50 yr old DL/VA and DL increased significantly when subjects moved from a sitting to a supine posture at volumes between 50 and 100% of total lung capacity (TLC). In subjects greater than 50 yr old the responses of DL/VA and DL to change in body position were not significant at TLC. Functional residual capacity (FRC) decreases and DL/VA increases in all normal subjects when they change position from sitting to supine. When DL/VA increases more than predicted from the DL/VA vs. VA relationship in a sitting position, we may infer an increase in effective Qc in the supine position. In 56% of the volunteers, supine DL was smaller than sitting DL despite a higher DL/VA at FRC in the supine position because of the relatively larger decrease in FRC. When the positional response at TLC is studied, an estimation obtained accidentally at a volume lower than TLC may influence results. Above 80% of TLC, Dm decreased significantly from sitting to supine. Below this lung volume the decrease was not significant. The relationship between Qc and VA was best described by a second-order polynomial characterized by a maximum Qc at a VA greater than 60% of TLC. Qc was significantly higher in the supine position than in the sitting position, but the difference became smaller with increasing age. In observing the sitting and supine positions, we saw a decrease in maximum Qc normalized per square meter of body surface area with age.

Differential changes of lung diffusing capacity and tissue volume in hypergravity

2002 ◽  
Vol 93 (3) ◽  
pp. 931-935 ◽  
Author(s):  
Malin Rohdin ◽  
Dag Linnarsson
Keyword(s):  
Blood Volume ◽  
Capillary Blood ◽  
Diffusing Capacity ◽  
Alveolar Volume ◽  
Tissue Volume ◽  
Dependent Part ◽  
Pulmonary Capillary ◽  
Capillary Blood Volume ◽  
Pulmonary Capillary Blood ◽  
Pulmonary Capillary Blood Volume

In normal gravity, lung diffusing capacity (Dl CO) and lung tissue volume (LTV; including pulmonary capillary blood volume) change in concert, for example, during shifts between upright and supine. Accordingly, Dl CO and LTV might be expected to decrease together in sitting subjects in hypergravity due to peripheral pooling of blood and reduced central blood volume. Nine sitting subjects in a human centrifuge were exposed to one, two, and three times increased gravity in the head-to-feet direction (Gz+) and rebreathed a gas containing trace amounts of acetylene and carbon monoxide. Dl CO was 25.2 ± 2.6, 20.0 ± 2.1, and 16.7 ± 1.7 ml · min−1 · mbar−1(means ± SE) at 1, 2, and 3 Gz+, respectively (ANOVA P < 0.001). Corresponding values for LTV increased from 541 ± 34 to 677 ± 43, and 756 ± 71 ml ( P < 0.001) at 2 and 3 Gz+. Results are compatible with sequestration of blood in the dependent part of the pulmonary circulation just as in the systemic counterpart. Dl CO, which under normoxic conditions is mainly determined by its membrane component, decreased despite an increased pulmonary capillary blood volume, most likely as a consequence of a less homogenous distribution of alveolar volume with respect to pulmonary capillary blood volume.

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