Pulmonary aspiration during emergency endoscopy in patients with upper gastrointestinal hemorrhage. OBJECTIVE: To evaluate the frequency and significance of aspiration and its clinical importance in patients with upper GI bleeding undergoing esophagogastroduodenoscopy in the ICU. DESIGN: Thirty consecutive patients with active and severe upper GI bleeding were studied. SETTING: ICU. PATIENTS: Ranged in age from 20 to 78 yr with an equal number of males and females. INTERVENTIONS: All patients had continuous pulse oximetry monitoring and had chest radiographs obtained less than 12 hr before endoscopy and less than 4 hr after endoscopy. MEASUREMENTS: Six (20%) of 30 patients developed new lung infiltrates after esophagogastroduodenoscopy. In this group of patients, preendoscopy chest radiographs were obtained after less than 4 hr. In five of these patients, infiltrates were accompanied by fever and/or leukocytosis and oxygen desaturation to less than 90% during the esophagogastroduodenoscopy. CONCLUSION: Clinically significant aspiration pneumonia frequently complicates esophagogastroduodenoscopy in upper GI bleeding patients and is an important mechanism of esophagogastroduodenoscopy-induced hypoxia. 