Falls in hemoglobin saturation during ERCP and upper gastrointestinal endoscopy

Fiberoptic endoscopy is practiced everyday in the field of gastroenterology and, for diagnostic purposes, carries a risk of complications and an estimated mortality of 1:5,000, which is multiplied several times during interventional procedures. Half of these complications have a cardiopulmonary origin which may be anticipated by the use of pulse oximetry to measure hemoglobin saturation (SaO2). We studied 132 patients undergoing diagnostic or procedural endoscopic retrograde cholangiopancreatography (ERCP) under sedation, and 51 undergoing esophagogastroduodenoscopy (EGD) without sedation. In the ERCP group, SaO2 fell from 95.7 +/- 2.4% (mean +/- standard deviation) to 88.9 +/- 6.4% (p less than 0.001) with a corresponding rise in pulse from 95 +/- 19 to 116 +/- 18/min (p less than 0.001) followed by recovery. The largest falls followed positioning of the endoscope (rather than following administration of the sedative or the procedure), particularly during introduction of the endoscope within 1 minute of administering diazemuls (diazepam). The EGD group also had a fall in SaO2 (97.3 +/- 1.9% to 93.9 +/- 3.3%, p less than 0.001), although the patients were younger and undergoing shorter examinations. Again, the largest falls occurred 1 minute after introduction of the endoscope. In subgroups of patients undergoing ERCP, analysis of respiratory patterns using spectral techniques and electrocardiogram during endoscopy (n = 25), or peripheral perfusion using transcutaneous oximetry and laser Doppler velocimetry (n = 12) was undertaken. No correlations were found in relation to changes in SaO2. The cause of the fall in SaO2 during endoscopy is multifactorial.(ABSTRACT TRUNCATED AT 250 WORDS)