Risk factors for respiratory depression in patients undergoing retrobulbar block for vitreoretinal surgery.

BACKGROUND AND OBJECTIVE To determine the risk factors for respiratory depression during retrobulbar block administration before vitreoretinal surgery. PATIENTS AND METHODS Prospective, observational case series of 113 patients undergoing monitored anesthesia care and retrobulbar block before vitreoretinal surgery at a tertiary medical center. RESULTS Chin lift, jaw thrust, and bag mask ventilation were performed in eight (7.1%), nine (8%), and six (5.3%) patients, respectively. No patients required intubation. Age, sex, body mass index, history of obstructive sleep apnea, American Society of Anesthesiologists physical status level, and baseline oxygen saturation were not predictive of airway intervention. Of the four anesthetic agents utilized (midazolam, fentanyl, alfentanil, and propofol), only propofol and fentanyl were associated with an increased risk for clinically significant apnea. Use of three medications for sedation was associated with a 5.4-fold increase in the relative risk of requiring a respiratory rescue intervention. CONCLUSION During preoperative sedation for retrobulbar block administration, the use of propofol, fentanyl, or a combination of three anesthetics is associated with a statistically significant increase in the risk for respiratory depression requiring resuscitation.