Oxygen desaturation and tachycardia during upper gastrointestinal endoscopy are transient and benign.

We continuously monitored the arterial oxygen saturation (SaO2) and pulse rate by pulse oximetry in 46 patients undergoing upper gastrointestinal endoscopy for diagnosis (21 cases) or variceal sclerotherapy (25). No premedication or prior topical anaesthesia was used. Significant hypoxaemia (percent drop in SaO2 > 2) occurred in 24 (52%) patients during the procedure; in 16 of these it occurred during introduction of the endoscope. Twenty seven (59%) patients had hypoxaemia during recovery, 25 of these immediately after withdrawal of the endoscope. All these episodes were short-lived and were probably due to gagging; basal levels were reached within 1 to 5 min. Tachycardia (> 100 beats/min) occurred in 41 (89%) patients. Sclerotherapy and history of smoking did not affect the incidence and magnitude of hypoxaemia and tachycardia. Transient cardio-respiratory changes occur during and immediately after endoscopy, but these appear to be clinically benign.