The purpose of this study is to measure the prostaglandin levels in patients with stress ulcer and the effect of Prevacid on prostaglandin levels in patients with stress ulcer.

The prostaglandin system plays an important role in the gastric mucosa to strengthen its resistance against injury. Critically ill patients are at greatest risk of developing stress-related gastric mucosal lesions. Although the levels of prostaglandins in gastric mucosa in patients with stressed animal has been studied, prostaglandin levels in the gastric mucosa in patients with stress ulcer have not been studied and the effect of Prevacid on prostaglandin levels in gastric mucosa from patients with stress ulcer is unknown.

We hypothesize that prostaglandin levels are low in the gastric mucosa in patients with stress ulcer, and Prevacid is an effective agents in increasing prostaglandin levels in the gastric mucosa in stress stress ulcer.

Comparison(s): The prostaglandin levels in patients who treated with Prevacid for stress ulcer, compared to the prostaglandin levels in patients who treated with H2 blocker for stress ulcer.

Inclusion Criteria:

• Patients in ICU with documented gastric stress ulcer by endoscopic examination, including patients with H. Pylori infection;
• Patients have no known ulcer within 8 weeks prior to be admitted to ICU;
• Patients not on any PPI for 4 weeks prior to the study;
• Patients or family be consented for the study.

Exclusion Criteria:

• Patients have gastric ulcer within 8 weeks prior to be admitted to ICU;
• Patients have gastric cancer confirmed by pathology;
• Patients on one of the PPIs already;
• Patients on any of the Non-steroidal Antiinflammatory Drugs.