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

OBJECTIVE

To determine whether a) pre-operative measurement of gastric intramucosal pHi is predictive for mortality and morbidity in high-risk surgical patients and b) peri-operative improvement of global oxygen delivery (DO2) with fluids and dopexamine leads to increased gastric pHi and c) either improved global perfusion or improved splanchnic perfusion is related to the prevention of multiple organ failure (MOF).

DESIGN

Retrospective analysis of a double-blind, placebo-controlled, randomised 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 stabilised pre-operatively using fluids, blood and/or oxygen to preset goals before receiving placebo or two doses of dopexamine (0.5 or 2.0 microg.kg.min) peri-operatively.

MEASUREMENTS AND RESULTS

Haemodynamic assessment (including DO2 and oxygen consumption (VO2)) was performed together with measurement of gastric mucosal pHi pre-operatively and directly, 2, 6, 12, 24 and 36 h post-operatively. Retrospectively, patients were divided pre-operatively into two sub-groups based on the optimal cut-off value for mortality of the first pHi measurement after induction of anaesthesia as calculated by a receiver operator characteristic (ROC) curve analysis --low pHi group (< 7.35) and normal pHi (> or =7.35). Mortality in the low pHi, was higher than in the normal pHi, group (16.8 vs 2.3%; p = 0.0001). In the normal pHi group dopexamine, which was given prior to the first pHi measurement, had no effect on pHi, while DO2 increased significantly. In this group MOF score and number of patients with 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 score and the number of patients developing MOF decreased significantly with the 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 pHi was predictive for mortality. The peri-operative response of pHi to dopexamine seemed to be dependent on pre-operative gastric pHi.