Ventilation-perfusion distribution after aortic valve replacement.

Abstract

In eight patients, the ventilation-perfusion (Va/Q) relationships after uncomplicated aortic valve replacement were studied by the multiple inert gas technique. Postoperatively, all patients had a right-to-left intrapulmonary shunt (Qsp/Qt) (range 2.4% to 14.4%) and abnormal distribution of Va/Q patterns to varying degrees. No single mechanism was identified that defined gas exchange in all patients. In three patients, moving from the supine to the right lateral decubitus position resulted in improved oxygenation which occurred because of better matching of Va/Q, not because of a decrease in Qsp/Qt.