Lung function and blood-gas exchange, before and after cardiac surgery.

Abstract

Lung volumes, bellows functions, and lung blood-gas distribution have been studied in 15 patients with severe acquired valvular heart disease. Nine of these patients were also studied after definitive surgical correction. Vital capacity which was decreased an average of 26% did not change postoperatively. Functional residual capacity, residual volume, and total lung capacity did not change significantly. Maximal voluntary ventilation and forced expiratory volume (1 sec) did not change significantly. No abnormality was detected in the intrapulmonary mixing of inspired gas either before or after operation. Mean arterial oxygen tension was 10–15 mm Hg lower than normal. The mean shunt fraction of total cardiac output was 3.1% and increased insignificantly to 4.1% postoperatively. The alveolar-arterial oxygen tension difference ((A – a)DO2) was high. However, no change was noted after operation. The nonshunt component of the (A – a)DO2 was higher than normal and did not change after operation. alveolar-arterial oxygen tension differences; lung function in acquired valvular heart disease; shunts; lung blood-gas distribution Submitted on June 29, 1964