Biomedical subjects

N Varène

Publications and source records attributed to N Varène.

3 recordsLinked to original sources

PubMed1991

Pulmonary diffusion limitation after prolonged strenuous exercise.

To determine the effect of strenuous prolonged exercise on alveolo-capillary membrane diffusing capacity, 11 marathon runners aged 37 +/- 7 years (mean +/- SD) were studied before and during early recovery (28 +/- 14 min) from a marathon race. Lung capillary blood volume (Vc) and the alveolo-capillary diffusing capacity (Dm) were determined in a one-step maneuver by simultaneous measurements of CO and NO lung transfer (DLCO and DLNO, respectively) using the single breath, breath-holding method. After the race, both DLCO and DLNO were significantly decreased in all subjects (-10.9 +/- 4.8%, P less than 10(-4) and -29.0 +/- 11.1%, P less than 10(-4), respectively). The mean value of the derived DmCO decreased by -29.3 +/- 11.1%, whereas Vc had not entirely returned to control resting value. Although these results do not indicate the detailed mechanism involved, interstitial lung fluid was suspected to accumulate, particularly in alveoli, during the race. We concluded that the high overall work load and the extended duration of the exercise both contributed to a transient change in the structure of the alveolo-capillary membrane thereby affecting the diffusing capacity of the alveolo-capillary membrane.

Adult↗

PubMedDate not supplied

[Inert gas study of heliox gas exchange in patients with COPD].

Ventilation and perfusion distributions were measured in the patients with COPD breathing room air and normoxic helium-oxygen mixture (heliox) successively, using the multiple inert gas method. The D (A-a) O2 were calculated from ideal alveolar gas (Ai) and with West's gas mean model (A). Measured PaO2 and predicted PaO2 were compared during room air and heliox breathing. There were no change in overall distributions and in D (Ai-a) while D (A-a) O2 increase significantly during heliox breathing and the predicted PaO2 were significantly higher than the measured PaO2. Heliox breathing does not seem to change parallel heterogeneity in COPD. These results suggest an impairment of series heterogeneity and O2 diffusion during heliox breathing.

Helium↗

PubMedDate not supplied

[Effects of oral almitrine on the distribution of VA/Q ratio in chronic obstructive lung diseases (author's transl)].

A double blind study of effects of a low dose of almitrine has been performed in patients with severe chronic obstructive lung diseases. Besides hemodynamic and ventilation data, ventilation-perfusion ratio distribution was measured by the inert gas method in order to try to explain the improvement in blood gases caused by this drug. At the dose of 1.5 mg/kg almitrine produces : 1) an increase in ventilation and PaO2, 2) no change in pulmonary vascular resistances compared to a rise on placebo, 3) a drop of 4% in the percentage of cardiac output perfusing low VA/Q lung units with a concomitant increase in lung units with VA/Q ratio between 0.1 and 10, and 4) no significant change in the distribution of ventilation. The change in the distribution of blood flow is one of the causes of the rise in PaO2, but its mechanism is at yet not clear. The present results suggest arterial vasoconstriction in units with very low VA/Q accompanied by diversion of blood flow towards lung units with higher VA/Q ratio.

Aged↗