New reference equations: What changes in diffusing capacity for carbon monoxide interpretation?

The aim of this study was to determine reference equations for the combined measurement of diffusing capacity of the lung for carbon monoxide (CO) and nitric oxide (NO) (DLCONO). In addition, we wanted to appeal for consensus regarding methodology of the measurement including calculation of diffusing capacity of the alveolo-capillary membrane (Dm) and pulmonary capillary volume (Vc).DLCONO was measured in 282 healthy individuals aged 18–97 years using the single-breath technique and a breath-hold time of 5 s (true apnoea period). The following values were used: 1) specific conductance of nitric oxide (θNO)=4.5 mLNO·mLblood−1·min−1·mmHg−1; 2) ratio of diffusing capacity of the membrane for NO and CO (DmNO/DmCO)=1.97; and 3) 1/red cell CO conductance (1/θCO)=(1.30+0.0041·mean capillary oxygen pressure)·(14.6/Hb concentration in g·dL−1).Reference equations were established for the outcomes of DLCONO, including DLCO and DLNO and the calculated values Dm and Vc. Independent variables were age, sex, height and age squared.By providing new reference equations and by appealing for consensus regarding the methodology, we hope to provide a basis for future studies and clinical use of this novel and interesting method.

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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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