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At least 19 recordsLinked to original sources
PubMed1993

Influence of exercise intensity and duration on post-exercise pulmonary diffusion capacity.

Pulmonary diffusion capacity has been observed to be reduced by approximately 14% 2h after 4-6 min of maximal exercise. The purpose of this study was to determine if the decrease in pulmonary diffusion capacity also occurs when the duration of exercise intensity is shorter or when the exercise intensity is lower. We measured pulmonary diffusion capacity using the single breath method in 12 competitive rowers 22 (16-31) years old, 70 (56-100) kg body weight, and 180 (171-193) cm body height under two conditions: (1) 2h after 6 min of rowing at both 61% (58%-68%) and 76% (73%-78%) of maximal oxygen uptake; (2) 2h after 1, 2, or 3 min of all-out rowing. Values are presented as medians with ranges. Pulmonary diffusion capacity was reduced by 6% (2%-17%) after 6 min of rowing at 61% and by 10% (-7%-21%) after 6 min of rowing at 76% of maximal oxygen uptake (p < 0.03). Pulmonary diffusion capacity was reduced by 7% (3%-19%), 8% (2%-17%) and 7% (1%-16%) after 1, 2, and 3 min of all-out rowing (p < 0.01). We conclude that submaximal exercise at 61% of maximal oxygen uptake will affect pulmonary diffusion capacity following exercise as will shorter duration of maximal exercise. Although the mechanism for this fall in pulmonary diffusion capacity is unclear, the fact that it occurs after even mild exercise makes a significant change in pulmonary capillary membrane integrity or subclinical pulmonary edema unlikely.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Morphometric model for pulmonary diffusing capacity. I. Membrane diffusing capacity.

The pulmonary diffusing capacity is related to the quantitative design characteristics of the pulmonary gas exchanger. The current model for estimating DLO2 from morphometric data breaks the diffusion path for O2 into four steps, three of which represent the membrane part of DLO2. A critique of this model on the basis of newer evidence leads to a modification of the model where the path from the alveolar surface to the erythrocyte membrane is considered as a single step. The structural determinant of this model for DMO2 is the ratio of effective diffusion surface to effective total barrier thickness. The effective surface is formulated as a fraction of the alveolar surface area, the most robust measure of lung design, whereas the effective barrier thickness is the harmonic mean distance--or mean proximity--between alveolar surface and erythrocyte surface. The methods for obtaining the morphometric measurements are discussed. The results show that the new morphometric estimates of DMO2 are 33% lower than those obtained with the old model, resulting in a reduction of the estimates of DLO2 by 10-20%.

Animals↗
PubMed1975

Smoking and pulmonary diffusing capacity.

The pulmonary diffusing capacity (DLCO SB) and its two components, the capillary blood volume (Vc) and the diffusing capacity of the membrane (DMCO), expressed in absolute values and per litre of alveolar volume (VA'), were measured at rest and on exercise in healthy male smokers and nonsmokers of similar age and height, and with identical values for haemoglobin and spirographic data. DLCO, DLCO/VA', DMCO and DMCO/VA' are significantly lower in smokers, at rest and on exercise; the decrease in Vc and thetaVc/VA' in smokers at rest is due to a higher level of carboxyhaemoglobin. The decrease of DLCO, DLCO/VA', DMCO and DMCO/VA' is apparently not due to carboxyhaemoglobin or distributional factors but to anatomical lesions, probably of emphysematous nature, altering the pulmonary membrane. Formulas predicting DLCO, DMCO, Vc, DLCO/VA', DMCO/VA' and thetaVc/VA' in terms of age and height were established in smokers and in nonsmokers.

Adult↗
PubMed1997

Pulmonary diffusing capacity and pulmonary capillary blood volume during parabolic flights.

Data from the Spacelab Life Sciences-1 (SLS-1) mission have shown sustained but moderate increase in pulmonary diffusing capacity (DL). Because of the occupational constraints of the mission, data were only obtained after 24 h of exposure to microgravity. Parabolic flights are often used to study some effects of microgravity, and we measured changes in DL occurring at the very onset of weightlessness. Measurements of DL, membrane diffusing capacity, and pulmonary capillary blood volume were made in 10 male subjects during the 20-s 0-G phases of parabolic flights performed by the "zero-G" Caravelle aircraft. Using the standardized single-breath technique, we measured DL for CO and nitric oxide simultaneously. We found significant increases in DL for CO (62%), in membrane diffusing capacity for CO (47%), in DL for nitric oxide (47%), and in pulmonary capillary blood volume (71%). We conclude that major changes in the alveolar membrane gas transfers and in the pulmonary capillary bed occur at the very onset of microgravity. Because these changes are much greater than those reported during sustained microgravity, the effects of rapid transition from hypergravity to microgravity during parabolic flights remain questionable.

Acceleration↗
PubMed1998

[Change of pulmonary diffusing capacity, membrane diffusing capacity and pulmonary capillary blood volume in patients with COPD and connective tissue disease at rest and post-exercise].

OBJECTIVE: Studying the changes of pulmonary diffusing capacity (DL), alveolar capillary membrane diffusing capacity (Dm) and pulmonary capillary blood volume (Vc) in patients with COPD and connective tissue disease (CTD) at rest and post-exercise; evaluating the diagnostic values of DL, Dm and Vc in early stage of pulmonary involvement of CTD. METHOD: Spirometry was performed in the sit position. Several measurements of diffusing capacity of the lung for carbon monoxide (DLCO) were measured by single-breath method at increasing alveolar oxygen tension. The estimations of Dm and Vc were done by the method of Roughton and Forster. RESULT: (1) In COPD group, the values of DL were lower than that of the control group at rest. The decreases were due to the reduction of Dm, but Vc were normal. In CTD group, all the value of DL, Dm and Vc were lower than that of its control group at rest. (2) COPD patients had the higher DL, Dm and Vc after the end of exercise than that of at rest. But the changes of DL Dm and Vc in COPD patients were lower compared with the control group. In contrast to the control group, DL, Dm and Vc did not increase or even decreased after the end of exercise in CTD group. (3) There was no significant differences of DL, Dm and Vc between the 7 CTD patients with normal pulmonary volume and DLCO and the control subjects at rest. But after the end of exercise, DL, Dm and Vc of CTD patients kept unchanging or even decreasing. The difference between CTD patients and its control group was found significant. CONCLUSION: The measurements of post-exercise Dm and Vc are sensitive tests for pulmonary involvement in of CTD patients. The results are abmormal much earlier in subject with minimal dyspnea and roentgenologic change. They are useful tests for early stage CTD.

Aged↗
PubMed2006

Comparison of carbon monoxide (CO) single breath pulmonary diffusing capacity with non-rebreathing, open-circuit CO pulmonary diffusing capacity in healthy children.

INTRODUCTION: The standard technique for assessing pulmonary diffusing capacity of the lungs (DL) for carbon monoxide (CO) is the single breath (SB) technique. SB_DLco in children can be problematic because it requires a vital capacity >1.5 L. We have developed an open-circuit technique (OC), which uses the wash-in of CO over a series of 8-10 normal breaths that does not require rebreathing. In this study, we compared the SB_DLco against the OC_DLco. METHODS: Nineteen healthy children between 7 and 18 years performed SB_DLco and OC_DLco tests. The mean SB_DLco was significantly larger than the mean OC_DLco. The mean difference OC_DLco minus SB_ DLco was: -2.92 +/- 4.21 ml/min/mm Hg, though the difference was negatively correlated with the mean of the two (r = 0.73). The lower mean OC_DLco was in part due to lower lung volume (as measured by alveolar volume (VA)) during the maneuver. In both groups there was a positive correlation between VA and DLco, and the mean VA was -2.17 +/- 1.07 L lower using OC compared to SB. The difference was again negatively correlated with the mean (r = 0.82). The mean OC minus SB difference in DLco/VA was: 6.06 +/- 1.98 ml/min/mm Hg/L, though this difference was positively correlated with the mean, r = 0.76. CONCLUSIONS: We found a good correlation between both techniques for DLco, VA, and DLco/VA. The OC offers the advantage of minimal subject cooperation, and may be preferable to use in children.

Adolescent↗
PubMed1992

Recovery of pulmonary diffusing capacity after maximal exercise.

Pulmonary diffusing capacity (DICO), together with spirometric variables, arterial oxygen tension (paO2) and cardiac output were determined before and at intervals after maximal arm cranking, treadmill running and ergometer rowing. Independent of the type of exercise, D1CO increased immediately post-exercise from a median 13.6 (range 7.3-16.3) to 15.1 (9.3-19.6) mmol min-1 kPa-1 (P < 0.01). However, it decreased to 11.6 (6.9-15.5) mmol min-1 kPa-1 (P < 0.01) after 24 h with cardiac output and paO2 at resting values, and D1CO normalized after 20 h. Thoracic electrical impedance at 2.5 and 100 kHz increased slightly post-exercise, indicating a decrease in thoracic fluid balance, and there were no echocardiographic signs of left ventricular failure at the time of the decrease in D1CO. Also, active muscle (limb) circumference and volume, and an increase in haematocrit from 43.8 (38.0-47.0) to 47.1 (42.7-49.8) (P < 0.01), had normalized at the time of the decrease in D1CO. Vital capacity, forced vital capacity, forced expiratory volume in 1 s, peak and peak mid-expiratory flows did not change. However, total lung capacity increased from 6.8 (5.0-7.6) to 7.0 (5.1-7.8) litres (P < 0.05) immediately after exercise and remained elevated at 6.9 (5.1-8.7) litres (P < 0.05) when a decrease in D1CO was noted. The results demonstrate that independent of the type of maximal exercise, an approximate 15% reduction in D1CO takes place 2-3 h post-exercise, which normalizes during the following day of recovery.

Adult↗