High incidence of postoperative metabolic alkalosis in surgical patients.

A retrospective study was undertaken to elucidate the changes of acid-base balance following general surgery. 2843 samples of arterial blood gas and pH determinations were obtained from 418 surgical patients before and after the operation. Before the operation, the incidence of acid-base disturbance was low, 79.5% of 190 determinations being normal in acid-base balance. During the postoperative period, metabolic alkalosis was the most common acid-base disturbance as has been observed in 39.5% of 2248 determinations, while respiratory alkalosis was less frequent, occurring in 13.3%. The incidences of other abnormalities were low before and after the operation except for a transient increase in metabolic acidosis on the day of operation. After the operation, metabolic alkalolosis was found most frequently, occurring in 47.5% of 1305 determinations during the first to seventh postoperative days, whereas an increase in respiratory alkalolosis was not clearly seen during this period. Metabolic alkalosis seemed to take a transient increase with the highest incidence being 60.1% on the fourth postoperative day. Further prospective controlled study is required to elucidate the incidence and the development of mechanism of postoperative metabolic alkalosis.