Gastric intramucosal acidosis in mechanically ventilated patients

Objective To investigate whether gastric intramucosal acidosis is associated with a decreased gastric mucosal blood flow in mechanically ventilated patients. Design Prospective, clinical investigation. Setting University hospital intensive care unit. Patients Seventeen mechanically ventilated patients with stable hemodynamic status. Interventions Gastric tonometry and endoscopic assessment of mucosal blood flow. Measurements and main results Six patients had gastric intramucosal acidosis (intramucosal pH [pHi] of 7.24 +/- 0.06), whereas the remaining 11 patients had pHi values within the normal range (7.44 +/- 0.01). No differences were found between intramucosal acidotic and nonacidotic patients with respect to their general and hemodynamic characteristics. Patients with intramucosal acidosis had a lower gastric mucosal blood flow, as assessed by laser-Doppler flowmetry, than nonacidotic patients (1.4 +/- 0.1 vs. 2.1 +/- 0.2 volts, respectively; p < .05). Reflectance spectrophotometry disclosed that patients with low gastric pHi had also a significantly (p < .05) lower hemoglobin content index (61 +/- 4 arbitrary units) than patients with normal pHi (81 +/- 3 arbitrary units), whereas oxygen saturation index was similar for both groups. Conclusion Our results support the hypothesis that gastric mucosal hypoperfusion underlies the development of intramucosal acidosis in mechanically ventilated patients.