Measurement of gastric intramucosal pH during abdominal surgical procedures

Background: Gastric mucosal pH may be a good indicator of splanchnic tissue oxygenation. Aim: To study the effects of abdominal surgical procedures on gastric mucosal pH. Patients and methods: Eighteen patients subjected to abdominal surgery were studied. All patients received general anesthesia and hemodynamic parameters were maintained within 20% of basal values. A tonometer was placed in the stomach after induction of anesthesia. Arterial blood gases and samples from the tonometer were obtained 30 minutes after induction and at 2 hours of surgery. Intramucosal pH was calculated using Henderson-Haselbach equations. Results: Basal gastric mucosal pH was 7.4 +/- 0.1 and did not change during surgery. Two patients had a pH persistently below 7.35 without hemodynamic alterations or systemic acidosis. Conclusions: Gastric mucosal pH is not modified by abdominal surgery and some patients have low values despite the absence of hemodynamic derangement.