Failure of cimetidine prophylaxis in the critically ill.

Stress ulcers with subsequent hemorrhage are a well-recognized cause of morbidity and mortality in patients hospitalized for other serious illnesses. In 39 critically ill patients, cimetidine was used as a prophylaxis against stress ulcers with the intent to keep the gastric pH level above 4. In 11 of the 39 patients, cimetidine alone did not effect consistent elevation of the gastric pH level above 4. Of the 11 patients, nine had positive blood cultures or clinical infection and five also developed renal failure. Five comatose patients never had pH greater than 4 on cimetidine alone. The mortality for those whose conditions failed to respond to cimetidine was five times greater than for those whose conditions responded to cimetidine. These data imply that a high-risk group of patients can be identified whose conditions may not respond to cimetidine treatment and whose gastric pH must be regularly monitored.