POTASSIUM IN CARDIAC SURGERY WITH EXTRACORPOREAL PERFUSION

Serum and urinary potassium variations during cardiac surgery with extracorporeal perfusion and in the immediate postoperative period were studied in 50 patients. The patients were divided into four groups: those with (1) congenital lesions; (2) cyanotic congenital lesions; (3) acquired lesions without diuretic therapy in the preoperative period; and (4) acquired lesions with diuretic therapy in the preoperative period. The uniform decrease in serum potassium during perfusion was confirmed in the four groups. In group II preoperative potassium levels were below normal range. In group IV low potassium levels were observed in the preoperative period, associated with respiratory alkalosis; subjects in this group had more instances of arrhythmias in the postoperative period than those in the other three groups. In the absence of dilutional or urinary potassium loss, the decrease in serum potassium is probably a consequence of its penetration into the body cells. Respiratory alkalosis due to anesthetic hyperventilation is an important factor contributing to this change. © 1969.