Update: Assessment of gastric pH in the critically ill.

The purpose of this manuscript is to update a review of the measurement of intraluminal gastric pH in the critically ill. Intraluminal gastric pH is readily measured by aspirates tested with litmus paper or a nasogastric tube with an antimony or glass electrode tip. Significant variations of intragastric pH have been shown in different stomach locations. Significant variations in the accuracy of pH readings have also been demonstrated. Prophylactic therapy in the critically ill is aimed at maintaining a gastric pH greater than 4.0 by drug therapy that 1) neutralizes acid, 2) interrupts the signal to produce acid, 3) reduces the amount of acid produced, or 4) enhances the mucosal barrier of the stomach lining. The critically ill patients at risk of respiratory failure or coagulopathy are the patients most at risk of gastrointestinal bleeding and are, therefore, the ones most likely to benefit from prophylactic therapy. Multiple pH readings are more reliable indicators of gastric pH than are individual readings. Continuous prophylaxis is more effective than intermittent.