Sedation Levels During Propofol Administration for Outpatient Colonoscopies

Abstract

The levels of sedation required for patients to comfortably undergo colonoscopy with propofol were examined. One hundred patients undergoing colonoscopy with propofol were enrolled. In addition to standard-of-care monitoring, sedation level was monitored with the Patient State Index (PSI) obtained from a brain function monitor, transcutaneous carbon dioxide (tcpCO 2 ) was monitored with the TCM TOSCA monitor, and end-tidal carbon dioxide was monitored via nasal cannula. The Ramsay Sedation Score (RSS) was also assessed and recorded. After baseline data were obtained from the first 40 consecutive patients enrolled in the study, the remaining 60 patients were randomized into two groups. In one group the PSI value was blinded from the anesthesiologist and in the second group the PSI was visible and the impact of this information on the management of the sedation was analyzed. Overall 96% of patients reached levels of deep sedation and 89% reached levels of general anesthesia. When comparing the blinded to PSI versus unblinded groups, the blinded group had a significantly lower PSI and higher RSS and tcpCO 2 , indicating the blinded group was maintained at a deeper sedation level with more respiratory compromise than the unblinded group. Patients undergoing colonoscopy under propofol sedation delivered by a bolus technique are frequently taken to levels of general anesthesia and are at risk for respiratory depression, airway obstruction, and hemodynamic compromise. P ropofol sedation for outpatient endoscopy has become a popular technique in place of midazolam and opioids, although the combination technique still has its proponents (1). Propofol alone has been associated with improved patient satisfaction and faster recovery with less nausea and vomiting (2) and has been recommended as a safe technique for patients when administered by nurses under the supervision of a physician-endoscopist (3-6). It has a very short onset of action and has a plasma half-life of 2 to 4 minutes, leading to a rapid recovery. However, a number of potential adverse eff ects are associated with propofol. It has no analgesic eff ects; therefore, when used for moderate sedation, propofol frequently has to be administered in amounts to provide deep levels of sedation to allow a painful procedure to be performed. Propofol-induced respiratory and cardiac depression is dose dependent and may put patients at risk, particularly if they have signifi cant comorbidities, so that supportive interventions may be necessary. However, the short duration of action will allow many patients to recover before