Objective Conscious sedation is widely used in endoscopic practice but is not without risk. We aimed to determine the frequency of sedation complications requiring reversal, and to identify potential patient and procedural risk factors.

Design A retrospective study of all gastrointestinal endoscopic procedures performed under conscious sedation, in a large three-campus tertiary referral endoscopic centre, between 12 October 2007 and 31 December 2012 (n=52 553). Flumazenil or naloxone administration was used as a marker of sedation complications requiring reversal. Reversal cases were analysed for associations with sedation dose, patient American Society of Anesthesiologists (ASA) grade, age and type of procedure undertaken.

Results In total, 149 sedation reversals occurred, representing 0.28% of all sedated endoscopic procedures carried out. Endoscopic Retrograde Cholangiopancreatography (ERCP) and increasing patient ASA grade were positively associated with sedation reversal (p<0.05). Mean midazolam dose was highest for ERCP (4.9±2.9 mg) and lowest for flexible sigmoidoscopy (1.7±0.6 mg; p<0.01). Mean opioid dose (calculated as pethidine equivalent) was highest for ERCP (62.9±38.7 mg) and lowest for gastroscopy (6.9±13.5 mg; p<0.01). Maximum doses of midazolam or opioid recommended by the British Society of Gastroenterology were exceeded in 7.4% and 14.1% of reversals, respectively.

Conclusions ERCP procedures and higher patient ASA grade were associated with an increased risk of conscious sedation-related complications requiring reversal. In these high-risk groups, alternative sedation strategies should be considered and tested. Prospective studies are needed to further explore risk factors that may help predict adverse sedation outcomes.