Early cognitive impairment after sedation for colonoscopy: the effect of adding midazolam and/or fentanyl to propofol

March 18, 2015

Authors: Usha Padmanabhan, Kate Leslie, Audrey Singyi Eer, Paul Maruff, Brendan S Silbert

Journal: Anesthesia and Analgesia

DOI: 10.1213/ane.0b013e3181a6ad31

Year Published: 2009


The sedative drug combination that produces minimal cognitive impairment and optimal operating conditions during colonoscopy has not been determined. We sought to determine if the use of propofol alone results in less cognitive impairment at discharge than the use of propofol plus midazolam and/or fentanyl in patients presenting for elective outpatient colonoscopy.


Two hundred adult patients presenting for elective outpatient colonoscopy were randomized to receive propofol alone or propofol plus midazolam, and/or fentanyl for IV sedation. Baseline cognitive function was measured using the computerized CogState test battery (Cogstate, Melbourne, Australia) before sedation. During the procedure, sedative drug doses, depth of sedation (via the bispectral index and observer’s assessment of alertness/sedation score), complications, and treatability were recorded. Patients were interviewed about recall immediately after emerging from sedation, and cognitive testing was repeated at hospital discharge. Recovery times, quality of recovery, and satisfaction with care were also recorded.


In the propofol plus adjuvants group, 84 patients received fentanyl 50 microg (25-100) (median [range]) and 57 patients received midazolam 2 mg (0.5-10). Patients’ cognitive function at discharge was worse than their performance at baseline. However, the changes in cognitive function between discharge and baseline were not significantly different between the two groups. At discharge, 18.5% of patients were cognitively impaired to an extent equivalent to a blood-alcohol concentration of 0.05%. Sedation with propofol plus midazolam and/or fentanyl produced better operating conditions than sedation with propofol alone and was associated with shorter procedure times. Recovery times, recall, dreaming, quality of recovery, and patient satisfaction with care were similar between the groups. Administration of >2 mg of midazolam was a predictor of impaired cognitive function at discharge.


Significant cognitive impairment was common at discharge from elective outpatient colonoscopy. However, the addition of midazolam and/or fentanyl to propofol sedation did not result in more cognitive impairment than the use of propofol alone. Furthermore, the use of adjuvants improved the ease of colonoscopy without increasing the rate of complications or prolonging early recovery times.

Back to Publications