Gastric secretion pH measurement: what you see is not what you get!

We evaluated the accuracy of gastric secretion pH measurements as performed in three ICUs. The pH of 275 samples was measured with pH paper using established techniques. The pH of 85 additional samples was determined with a hand-held pH meter. All specimens also were measured using a research laboratory pH meter to learn the true pH. Analyses included mean and SD of the difference between the two measurements, the correlation coefficient (r value), and the concordance correlation coefficient. The pH meter values disagreed significantly with pH paper measurements. Measurements of gastric secretion pH with pH indicator paper do not guide therapy reliably. Inaccurate values derived from pH paper measurements could have resulted in inappropriate treatment in 28% of the samples tested. A portable, battery-powered pH meter accurately reproduced laboratory pH meter measurements and is a reasonable device for clinical use.