General anesthesia causes depression of airway reflexes that predisposes patients to aspiration. Aspiration of gastric contents from vomiting or regurgitation may cause bronchospasm, hypoxemia, atelectasis, tachypnea, tachycardia, and hypotension. The severity of symptoms depends on the volume and pH of the gastric material aspirated. Conditions that predispose to aspiration include gastric dysmotility, gastric outlet obstruction, gastroesophageal reflux, small-bowel obstruction, symptomatic hiatal hernia, pregnancy, and recent food ingestion.