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 (tcpCO2) 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 tcpCO2, 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.

Figure 1.

Measurements at the onset of airway interventions: (a) cumulative percentage of airway intervention as Patient State Index value decreases and (b) end-tidal carbon dioxide level at the time of an airway intervention.