Comparison of continuous pH-meter and intermittent pH paper monitoring of gastric pH in critically ill children.

ABSTRACT

OBJECTIVE: A gastric pH below 4 increases the risk of gastrointestinal hemorrhage in critically ill patients. The pH can be monitored intermittently by testing the gastric aspirate using pH paper or continuously using a pH-meter (often in combination with multichannel intraluminal impedance). The objective of this study was to compare these two methods of pH measurement. METHODS: An observational, prospective study was conducted in critically ill children between 1 month and 14 years with at least two risk factors for gastrointestinal hemorrhage. Gastric pH was measured continuously by a multichannel pH-meter tube and every 2 h using pH paper on aspirates of gastric juice. RESULTS: A total of 471 gastric pH measurements were analyzed. The mean gastric pH measured by the pH-meter was 4.3±2.5 and that by pH paper was 3.9±2.2. The gastric pH was above 4 in 49.6% of the measurements taken on the basis of the gastric aspirate and in 49.8% of the pH-meter readings. The correlation between the two methods was moderate (0.59; P<0.001) but the concordance was low (0.54). The concordance with regard to determining a gastric pH above or below 4 was 77%. CONCLUSION: pH paper is a simple and inexpensive method that can be useful for initial patient monitoring, but it should not be used as a substitute for monitoring by pH-meter in patients in whom strict control of the gastric pH is required.