AIM To observe the predictive value of gastric intramucosal pH (pHi) for critical patients.METHODS The gastric intramucosal pH (pHi) of 32 ICU patients was measured with a self-madegastrointestinal tonometer, and the APACHE l score was determined simultaneously.RESULTS pHi of the nonsurvivors was significantly lower than that of the survivors (P<0.05). The pHiwas remarkably higher in the nonsepsis group than in the sepsis group (P<0.01). Only in multiple organfailure groups, pHi was found statistically lower (P<0.05).CONCLUSION pHi may be the most simple, reliable, sensitive and accurate parameter to indicate theadequacy of tissue oxygenation, and it may be widely used in ICU monitoring in near future.