Background and aim: Hypoxemia is the most common unexpected cardiopulmonary complication that is used as a surrogate for severe complications in colonoscopy. The aim of the present study was to access the STOP Questionnaire to screen for hypoxemia in deep sedation for colonoscopy in young and middle-aged outpatients.
Methods: Outpatients aged 18-65 with ASA class I or II who were to undergo elective colonoscopy with deep sedation were offered participation. Before sedation, the patients were given the STOP Questionnaire, a brief survey that stratifies patients into high or low risk of hypoxemia. Data on pulse oxygen saturation (SpO(2) ) were collected during sedation. Hypoxemia was defined as SpO(2)<95% anytime during the procedure, regardless of episode duration. We estimated the score of the STOP Questionnaire and the incidence of hypoxemia.
Results: A total of 210 consecutive outpatients were offered enrollment. Thirteen (6.2%) patients had hypoxemia. Thirty-two (15.2%) patients were scored to be at high risk of hypoxemia, of whom 10 had hypoxemia. Results of analyzing the STOP Questionnaire for the incidence of hypoxemia were sensitivity 76.9%, specificity 88.8%, Youden's index 0.658, consistency rate 88%, kappa value 0.39, positive predictive value 31.3%, negative predictive value 98.3%, and area under receiver operating characteristic (ROC) curve 0.935 (P<0.001, 95% CI 0.879-0.991).
Conclusions: STOP Questionnaire is a validated and easy-to-use screening tool for hypoxemia in outpatient colonoscopy. It has high sensitivity, specificity and negative predictive value.
© 2011 The Authors. Digestive Endoscopy © 2011 Japan Gastroenterological Endoscopy Society.