Gastric intramucosal pH and blood lactate in severe sepsis

We prospectively investigated the effect of conventional resuscitation on gastric intramucosal pH and lactate over 5 days in a group of patients with newly diagnosed severe sepsis. Lactate and gastric intramucosal pH were measured on entry into the study, as soon as resuscitation end points were met, eight hourly for 48 h and daily for 5 days. Sixteen of 18 patients had a low gastric intramucosal pH (mean (SD) 7.17 (0.12)) at the time of diagnosis of severe sepsis. At no time did gastric intramucosal pH or lactate distinguish between shocked and nonshocked patients. Lactate distinguished survivors from nonsurvivors over time (p = 0.02). Gastric intramucosal pH did not distinguish survivors from nonsurvivors over time (p = 0.72). At 48 h lactate was lower in survivors (p < 0.01) and gastric intramucosal pH higher in survivors (p < 0.05). Receiver operating characteristic curves at this time indicate that lactate is a better predictor of survival. It is likely, based on the inability of gastric intramucosal pH to distinguish survivors from nonsurvivors until 48 h, that it is not possible to use this measurement to guide resuscitation in patients who are severely ill and who have gastric intramucosal acidosis.