Study objective: To evaluate gastric alkalization and bacterial colonization in critically ill patients receiving stress ulcer prophylaxis with gastric tube feeds, sucralfate, intermittent intravenous cimetidine, or continuous intravenous cimetidine. DESIGN; Prospective, randomized, unblinded trial.
Setting: Medical and surgical intensive care units of a large university-affiliated, tertiary care community hospital.
Patients: Fifty-three evaluable critically ill patients with respiratory failure requiring mechanical ventilation.
Interventions: Patients not receiving nasogastric tube feeds were randomized to sucralfate 1 g every 6 hours, cimetidine 300 mg by intravenous bolus every 8 hours, or cimetidine 900 mg by continuous intravenous infusion/24 hours. Gastric samples were obtained daily for pH and culture.
Measurements and main results: Patients with respiratory failure and a high mortality rate had a mean gastric pH of 1.96 +/- 1.5 at study entry. There were no significant differences in gastric pH or gastric colonization among the three arms. Fourteen patients (26%) developed gastric colonization, which was statistically significant but poorly correlated with gastric alkalinity (r2=0.08, p<0.043).
Conclusion: Gastric luminal pH was unchanged regardless of which method was used for stress ulcer prophylaxis. Bacterial colonization was increasingly likely in patients with a persistent alkaline gastric environment.