Impact of continuous veno-venous hemodiafiltration on gastric mucosal carbon dioxide concentrations

Objective: The impact of the start of continuous veno-venous haemodiafiltration (CVVHDF) on gastric mucosal carbon dioxide concentration (PiCO2) - a marker of gastric mucosal perfusion and CO2 production - was studied. Design: Prospective observational study. Setting: University hospital medical intensive care unit (ICU). Subjects: Sixteen critically ill haemodynamically stable patients (APACHE II on admission 30±7) with multiple organ dysfunction syndrome, in whom CVVHDF was started because of acute renal failure were studied. Two patients were excluded from the analysis because of major haemodynamic instability during the study period. Interventions: Initiation of CVVHDF, placement of gastric tonometer. Measurements and main results: PiCO2 was measured using saline tonometry in 13 patients, and air tonometry in one patient at baseline and then at 1,2,3 and 6 h after starting CVVHDF. A gastric-arterial CO2 gap of > 15 torr (2 kPa) was chosen asa cut-off value of the presence of gastric musocal acidosi...