THE DIFFUSING CAPACITY OF THE LUNGS IN PATIENTS WITH MITRAL STENOSIS STUDIED POST-OPERATIVELY 1

Abstract

Studies of pulmonary function are reported in 14 patients on whom mitral valvulotomy was performed 5-55 months previously. Pulmonary ventilation, intrapulmonary distribution of blood and gas, and diffusing capacity were measured. Findings are related to preoperative studies previously reported. Although significant incapacity had existed over a period of years pre-operatively, approximately half of the patients showed post-operative diffusing capacities during exercise which were within one standard deviation of the predicted normal values for maximal diffusing capacity. The other patients showed moderate to severe lowering of diffusing capacity during exercise. The patients with diffusing capacities during exercise which were normal probably did not have extensive structural changes in the pulmonary membrane. The 2 with very low values probably did have extensive structural changes. Intermediate values could not be interpreted. All 6 of the patients who were studied pre-operatively at rest showed low diffusing capacities. Since all were greatly improved following mitral valvulotomy, a low pre-operative diffusing capacity is not considered a contraindication to surgery.