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 ≤90%) 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 ≥ 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 ≥ 60 years and meperidine dose were significant risk factors for hypoxemia.