Critically ill patients are at an increased risk of having upper gastrointestinal (GI) bleeding due to stress related mucosal damage. Cimetidine, delivered continuously through intravenous infusion, is the only drug that the FDA has approved for the prevention of upper GI bleeding in critically ill patients. The present trial is intended to assess the safety and efficacy of an omeprazole sodium bicarbonate immediate-release suspension in this indication.