Risk Factors for Hypoxemia During Ambulatory Gastrointestinal Endoscopy in ASA I-II Patients

Background Most studies identify the American Society of Anesthesiology (ASA) classification as the most significant risk factor for hypoxemia. The risk factors operative within ASA I and II patients are not well defined. Therefore, we analyzed prospectively collected data to identify the risk factors of hypoxemia in such patients. Methods A combination of a narcotic and benzodiazepine was used for sedation and oxygen was supplemented if hypoxemia (oxygen saturation a parts per thousand currency sign90%) developed. Univariate and multivariate analyses were performed and correlations estimated for predetermined clinical variables. Results 40 of 79 patients (51%) developed hypoxemia, which occurred more frequently in the obese (71%; 10/14) than the nonobese (46%; 30/65) group (P = 0.08). On multivariate analysis, the odds ratios (OR) and 95% confidence intervals (CI) for developing hypoxemia were age a parts per thousand yen 60 years 4.5 (1.4-14.3) P = 0.01, and incremental 25-mg doses of meperidine 2.6 (1.02-6.6) P = 0.04. Body mass index (BMI) significantly correlated with the number of hypoxemic episodes (rho 0.26, 95% CI 0.04-0.48, P = 0.02). Conclusion In ASA I and II patients, BMI significantly correlated with the number of hypoxemic episodes, whereas age a parts per thousand yen 60 years and meperidine dose were significant risk factors for hypoxemia.