Reduction of lung perfusion increases VA/Q heterogeneity.
This study addresses the hypothesis that decreases in lung perfusion rate independently worsen gas exchange efficiency in an isolated left lower lobe in zone 2 conditions. In seven anesthetized dogs, the left lower lobe was isolated, leaving the bronchus and bronchial vasculature intact. Blood was taken from the femoral arteries and reinfused at a controlled rate into the pulmonary artery of the left lower lobe. The flow rate was varied between 100 and 400 ml/min. The multiple inert gas elimination technique was used to quantitate the matching of ventilation to perfusion. Reduction in lobe blood flow resulted in a significant increase in perfusion-related indexes of alveolar ventilation-perfusion heterogeneity, such as the log standard deviation of the perfusion distribution, the retention component of the arterial-alveolar difference area, and the retention dispersion index. The increased heterogeneity suggests a worsening of the intraregional matching between the ventilation and the perfusion when perfusion is less than normal.
Ohlsson
J
J
Department of Physiology, University of Washington, Seattle 98195.
Middaugh
M
M
Hlastala
M P
MP
D000818:Animals; D002245:Carbon Dioxide / Q000097:blood; D004285:Dogs; D005260:Female; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008168:Lung / Q000502:physiology*; D008297:Male; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D011652:Pulmonary Circulation; D014692:Ventilation-Perfusion Ratio
D002245:Carbon Dioxide; D010100:Oxygen