Continuous intragastric pH measurement in the critically ill and treatment with parenteral ranitidine.

Continuous measurement of gastric pH using a flexible pH electrode attached to a NG tube was performed in nineteen critically ill patients. The gastric pH readings correlated well with hourly intermittent pH values using indicator strips. Hypotension, physiotherapy and septicaemia was consistently associated with falls in gastric pH. A continuous infusion of Ranitidine, a H2-receptor antagonist, was titrated against the continuously measured gastric pH in an attempt to keep it above a pH of 4. This was successfully achieved in sixteen of the nineteen patients using widely variable doses of Ranitidine. The three patients whose gastric pH remained low all had severe septicaemia.