Pre-operative tonometry is predictive for mortality and morbidity in high-risk surgical patients

Objective: To determine whether a) pre-operative measurement of gastric int ramucosal pHi is predictive for mortality and morbidity in high-risk surgic al patients and b) peri-operative improvement of global oxygen delivery (DO 2) with fluids and dopexamine leads to increased gastric pHi and c) either improved global perfusion or improved splanchnic perfusion is related to th e prevention of multiple organ failure (MOF). Design: Retrospective analysis of a double-blind, placebo-controlled, rando mised study. Setting: General intensive care units from 14 hospitals. Patients: Two hundred eighty-six high-risk surgical patients. Interventions: Swan-Ganz and tonometer catheter placement; patients were st abilised pre-operatively using fluids, blood and/or oxygen to preset goals before receiving placebo or two doses of dopexamine (0.5 or 2.0 mu g(.)kg(. )min) peri-operatively. Measurements and results: Haemodynamic assessment (including DO2 and oxygen consumption (VO2)) was performed together with measurement of gastric muco sal pHi pre-operatively and directly, 2, 6, 12, 24 and 36 h post-operativel y. Retrospectively, patients were divided pre-operatively into two sub-grou ps based on the optimal cut-off value for mortality of the first pHi measur ement after induction of anaesthesia as calculated by a receiver operator c haracteristic (ROC) curve analysis - low pHi group (< 7.35) and normal pHi (17.35). Mortality in the low pi-Ii, was higher than in the normal pHi, gro up (16.8 vs 2.3 %; p = 0.0001). In the normal pHi group dopexamine, which w as given prior to the first pHi measurement, had no effect on pHi, while DO 2 increased significantly. In this group MOF score and number of patients w ith MOF remained similar for the treatment sub-groups. In the low pHi group gastric pHi increased significantly during dopexamine infusion (p = 0.008) , despite the lack of an increase in DO2 and VO2. In this group the MOF sco re and the number of patients developing MOF decreased significantly with t he use of dopexamine (p = 0.04). In both groups bicarbonate levels remained similar for the treatment subgroups. Conclusions: In high-risk surgical patients pre-operative measurement of pH i was predictive for mortality. The peri-operative response of pHi Co dopex amine seemed to be dependent on pre-operative gastric pHi.