Rest and Exercise Cardiac Output and Diffusing Capacity Assessed By a Single Slow Exhalation of Methane, Acetylene, and Carbon Monoxide

We have previously shown that airway hypoxia causes pulmonary capillary recruitment and raises diffusing capacity for carbon monoxide. This study was designed to determine whether these events were caused by an increase in pulmonary vascular resistance, which redistributed blood flow toward the top of the lung, or by an increase in cardiac output. We measured capillary recruitment at the top of the dog lung by in vivo microscopy, gas exchange surface area of the whole lung by diffusing capacity for carbon monoxide, and blood flow distribution by radioactive microspheres. During airway hypoxia recruitment occurred, diffusing capacity increased, and blood flow was redistributed upward. When a vasodilator was infused while holding hypoxia constant, these effects were reversed; i. e., capillary “derecruitment” occurred, diffusing capacity decreased, and blood flow was redistributed back toward the bottom of the lung. The vasodilator was infused at a rate that left hypoxic cardiac output unchanged. These data show that widespread capillary recruitment during hypoxia is caused by increased vascular resistance and the resulting upward blood flow redistribution.

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An open-circuit method for determining lung diffusing capacity during exercise: comparison to rebreathe

Journal of Applied Physiology ◽

10.1152/japplphysiol.00348.2005 ◽

2005 ◽

Vol 99 (5) ◽

pp. 1985-1991 ◽

Cited By ~ 26

Author(s):

Eric M. Snyder ◽

Bruce D. Johnson ◽

Kenneth C. Beck

Keyword(s):

Cardiac Output ◽

Breathing Pattern ◽

Open Circuit ◽

Diffusing Capacity ◽

External Work ◽

Capillary Recruitment ◽

Single Breath ◽

Circuit Technique ◽

Alveolar Capillary ◽

Rest And Exercise

To avoid limitations associated with the use of single-breath and rebreathe methods for assessing the lung diffusing capacity for carbon monoxide (DlCO) during exercise, we developed an open-circuit technique. This method does not require rebreathing or alterations in breathing pattern and can be performed with little cognition on the part of the patient. To determine how this technique compared with the traditional rebreathe (DlCO,RB) method, we performed both the open-circuit (DlCO,OC) and the DlCO,RB methods at rest and during exercise (25, 50, and 75% of peak work) in 11 healthy subjects [mean age = 34 yr (SD 11)]. Both DlCO,OC and DlCO,RB increased linearly with cardiac output and external work. There was a good correlation between DlCO,OC and DlCO,RB for rest and exercise (mean of individual r2 = 0.88, overall r2 = 0.69, slope = 0.97). DlCO,OC and DlCO,RB were similar at rest and during exercise [e.g., rest = 27.2 (SD 5.8) vs. 29.3 (SD 5.2), and 75% peak work = 44.0 (SD 7.0) vs. 41.2 ml·min−1·mmHg−1 (SD 6.7) for DlCO,OC vs. DlCO,RB]. The coefficient of variation for repeat measurements of DlCO,OC was 7.9% at rest and averaged 3.9% during exercise. These data suggest that the DlCO,OC method is a reproducible, well-tolerated alternative for determining DlCO, particularly during exercise. The method is linearly associated with cardiac output, suggesting increased alveolar-capillary recruitment, and values were similar to the traditional rebreathe method.

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Predicting diffusive alveolar oxygen transfer from carbon monoxide-diffusing capacity in exercising foxhounds

Journal of Applied Physiology ◽

10.1152/japplphysiol.01328.2007 ◽

2008 ◽

Vol 105 (5) ◽

pp. 1441-1447 ◽

Cited By ~ 9

Author(s):

Connie C. W. Hsia ◽

Peter D. Wagner ◽

D. Merrill Dane ◽

Harrieth E. Wagner ◽

Robert L. Johnson

Keyword(s):

Carbon Monoxide ◽

Cardiac Output ◽

Lung Resection ◽

Capillary Blood ◽

Diffusing Capacity ◽

Heavy Exercise ◽

Fick Principle ◽

Capillary Blood Volume ◽

Pulmonary Capillary Blood ◽

Alveolar Oxygen

Although lung diffusing capacity for carbon monoxide (DlCO) is a widely used test of diffusive O2 transfer, few studies have directly related DlCO to O2-diffusing capacity (DlO2); none has used the components of DlCO, i.e., conductance of alveolar membrane and capillary blood, to predict DlO2 from rest to exercise. To understand the relationship between DlCO and DlO2 at matched levels of cardiac output, we analyzed cumulative data from rest to heavy exercise in 43 adult dogs, with normal lungs or reduced lung capacity following lung resection, that were studied by two techniques. 1) A rebreathing (RB) technique was used to measure DlCO and pulmonary blood flow at two O2 tensions, independent of O2 exchange. DlCO was partitioned into CO-diffusing capacity of alveolar membrane and pulmonary capillary blood volume using the Roughton-Forster equation and converted into an equivalent DlO2, [DlO2(RB)]. 2) A multiple inert-gas elimination technique (MIGET) was used to measure ventilation-perfusion distributions, O2 and CO2 exchange under hypoxia, to derive DlO2 [DlO2(MIGET)] by the Lilienthal-Riley technique and Bohr integration. For direct comparisons, DlO2(RB) was interpolated to the cardiac output measured by the Fick principle corresponding to DlO2(MIGET). The DlO2-to-DlCO ratio averaged 1.61. Correlation between DlO2(RB) and DlO2(MIGET) was similar in normal and post-resection groups. Overall, DlO2(MIGET) = 0.975 DlO2(RB); mean difference between the two techniques was under 5% for both animal groups. We conclude that, despite various uncertainties inherent in these two disparate methods, the Roughton-Forster equation adequately predicts diffusive O2 transfer from rest to heavy exercise in canines with normal, as well as reduced, lung capacities.

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Influence of age on pulmonary diffusing capacity

Journal of Applied Physiology ◽

10.1152/jappl.1959.14.4.483 ◽

1959 ◽

Vol 14 (4) ◽

pp. 483-492 ◽

Cited By ~ 37

Author(s):

R. E. Donevan ◽

W. H. Palmer ◽

C. J. Varvis ◽

D. V. Bates

Keyword(s):

Carbon Monoxide ◽

Cardiac Output ◽

Oxygen Uptake ◽

Pulmonary Function ◽

Normal Subjects ◽

Diffusing Capacity ◽

O2 Uptake ◽

Pulmonary Diffusing Capacity ◽

Simultaneous Measurements ◽

End Tidal

The pulmonary function of 24 normal subjects ranging in age from 20 to 50 years has been studied at rest and during exercise. At rest there is a significant decrease with age in the pulmonary diffusing capacity and the level of diffusing capacity attained on exercise at any particular oxygen uptake decreases with increasing age. Simultaneous measurements of O2 uptake, ventilation, end tidal O2 and CO2 concentration and calculated alveolar CO2 concentration, using the Bohr equation, show no evidence that any of these measurements are significantly influenced by age. The predicted maximal O2 diffusing capacity ( J. Appl. Physiol. 6: 588, 1954) predicts with fair accuracy the diffusing capacity for carbon monoxide that will be found in any given individual at an O2 uptake of about 2.8 l/min. It correctly predicts the change in CO diffusing capacity with increasing age. Reasons are given for suggesting that the decrease in pulmonary diffusing capacity observed may be explained by a diminution in cardiac output with increasing age. Submitted on November 21, 1958

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Reduced exercise tolerance in mild chronic obstructive pulmonary disease: The contribution of combined abnormalities of diffusing capacity for carbon monoxide and ventilatory efficiency

Respirology ◽

10.1111/resp.14045 ◽

2021 ◽

Author(s):

Devin B. Phillips ◽

Matthew D. James ◽

Amany F. Elbehairy ◽

Kathryn M. Milne ◽

Sandra G. Vincent ◽

...

Keyword(s):

Chronic Obstructive Pulmonary Disease ◽

Carbon Monoxide ◽

Pulmonary Disease ◽

Exercise Tolerance ◽

Chronic Obstructive ◽

Diffusing Capacity ◽

Obstructive Pulmonary Disease ◽

Ventilatory Efficiency

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The effect of conductive ventilation heterogeneity on diffusing capacity measurement

Journal of Applied Physiology ◽

10.1152/japplphysiol.00917.2007 ◽

2008 ◽

Vol 104 (4) ◽

pp. 1094-1100 ◽

Cited By ~ 9

Author(s):

Sylvia Verbanck ◽

Daniel Schuermans ◽

Sophie Van Malderen ◽

Walter Vincken ◽

Bruce Thompson

Keyword(s):

Carbon Monoxide ◽

Vital Capacity ◽

Experimental Situation ◽

Normal Subjects ◽

Diffusing Capacity ◽

Capacity Measurement ◽

Alveolar Volume ◽

Estimation Errors ◽

Single Breath ◽

Ventilation Heterogeneity

It has long been assumed that the ventilation heterogeneity associated with lung disease could, in itself, affect the measurement of carbon monoxide transfer factor. The aim of this study was to investigate the potential estimation errors of carbon monoxide diffusing capacity (DlCO) measurement that are specifically due to conductive ventilation heterogeneity, i.e., due to a combination of ventilation heterogeneity and flow asynchrony between lung units larger than acini. We induced conductive airway ventilation heterogeneity in 35 never-smoker normal subjects by histamine provocation and related the resulting changes in conductive ventilation heterogeneity (derived from the multiple-breath washout test) to corresponding changes in diffusing capacity, alveolar volume, and inspired vital capacity (derived from the single-breath DlCO method). Average conductive ventilation heterogeneity doubled ( P < 0.001), whereas DlCO decreased by 6% ( P < 0.001), with no correlation between individual data ( P > 0.1). Average inspired vital capacity and alveolar volume both decreased significantly by, respectively, 6 and 3%, and the individual changes in alveolar volume and in conductive ventilation heterogeneity were correlated ( r = −0.46; P = 0.006). These findings can be brought in agreement with recent modeling work, where specific ventilation heterogeneity resulting from different distributions of either inspired volume or end-expiratory lung volume have been shown to affect DlCO estimation errors in opposite ways. Even in the presence of flow asynchrony, these errors appear to largely cancel out in our experimental situation of histamine-induced conductive ventilation heterogeneity. Finally, we also predicted which alternative combination of specific ventilation heterogeneity and flow asynchrony could affect DlCO estimate in a more substantial fashion in diseased lungs, irrespective of any diffusion-dependent effects.

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Nonlinear increases in diffusing capacity during exercise by seated and supine subjects

Journal of Applied Physiology ◽

10.1152/jappl.1981.51.4.858 ◽

1981 ◽

Vol 51 (4) ◽

pp. 858-863 ◽

Cited By ~ 31

Author(s):

D. L. Stokes ◽

N. R. MacIntyre ◽

J. A. Nadel

Keyword(s):

Carbon Monoxide ◽

Oxygen Consumption ◽

Healthy Subjects ◽

Vital Capacity ◽

Maximal Exercise ◽

Sitting Position ◽

Diffusing Capacity ◽

Heavy Exercise ◽

Lung Volumes ◽

Rate Of Increase

To study the effects of exercise on pulmonary diffusing capacity, we measured the lungs' diffusing capacity for carbon monoxide (DLCO) during exhalation from 30 to 45% exhaled vital capacity in eight healthy subjects at rest and during exercise while both sitting and supine. We found that DLCO at these lung volumes in resting subjects was 26.3 +/- 3.2% (mean +/- SE) higher in the supine than in the sitting position (P less than 0.001). We also found that, in both positions, DLCO at these lung volumes increased significantly (P less than 0.001) with increasing exercise and approached similar values at maximal exercise. The pattern of increase in DLCO with an increase in oxygen consumption in both positions was curvilinear in that the rate of increase in DLCO during mild exercise was greater than the rate of increase in DLCO during heavy exercise (P = 0.02). Furthermore, in the supine position during exercise, it appeared that DLCO reached a physiological maximum.

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