COMPARISON OF GASTRIC-MUCOSAL PH AND CLINICAL JUDGMENT IN CRITICALLY ILL PATIENTS

Objectives: To compare gastric tonometry (pHi) with estimates of pH in ill injured patients, and to correlate pi-Ii with haemodynamic variab les. Design: Prospective, non-interventional study. Setting: ICU of Le vel I trauma centre, USA. Main outcome measures: 154 gastric tonometry measurements were compared with physicians' estimates of adequacy of resuscitation. Resuscitation was categorised as inadequate (pHi < 7.35 ) or adequate (pHi greater than or equal to 7.35). Measured and estima ted pHi were also compared with oxygen delivery, oxygen consumption, c ardiac index, mixed venous O-2 saturation, and critical illness scores . Results: Estimated pHi was often higher than measured pi-Ii in the j udgement of all four surgical intensive care physicians. Measured pHi correlated positively with mixed venous O-2 tension (r = 0.21). There were significant negative correlations between measured pHi and both o xygen delivery (r = -0.25) and oxygen consumption (r- = -0.28). Estima ted pHi correlated positively with mean arterial pressure (r = 0.21) a nd hospital day (r = 0.26); it correlated negatively with pulmonary ar terial elastance (r= -0.35). Conclusion: Experienced intensive care ph ysicians tended to overestimate visceral perfusion, which suggests tha t gastric tonometry adds useful information over and above routine hae modynamic indices. Arterial blood pressure and mixed venous oxygen sat uration correlated better with measured pHi than with other indices of perfusion.