Metabolic alkalosis and acid urine following open-heart surgery with cardiopulmonary bypass

Abstract

Acid-base and urine pH changes were investigated in seventy-eight patients undergoing open-heart surgery with cardiopulmonary bypass. When acid-citrate-dextrose blood was used to prime the heart-lung machine postoperative metabolic alkalosis associated with a significant increase in urine acidity was found in both acquired and congenital heart disease. Postoperative acid-base and urine pH changes were less marked in patients with congenital heart disease when edglugate-Mg priming blood was used. Protracted recovery from operation was associated with continuing metabolic alkalosis. In a small pilot study, base excess was reduced in five patients following acetazolamide (Diamox) therapy. The significance of these findings is discussed and it is suggested that in metabolic alkalosis, measurement of the urine pH is an important adjunct to blood-gas analysis. © 1968 John Sherratt and Son Ltd.