Purpose: Propofol and midazolam are popular sedatives in colonoscopy. Our aim was to measure depth of sedation with propofol-fentanyl and midazolam-fentanyl in patients undergoing colonoscopy using a blinded electroencephalogram (EEG)-based SEDLine monitor.
Methods: 108 adult volunteers were enrolled in this non-randomized, prospective, observational research. Patients with American Society of Anesthesiologist (ASA) class I-II-III, aged 18-80, and undergoing colonoscopy with propofol-fentanyl (Group P) (0.5-3 mg/kg-1 µg/kg) or midazolam-fentanyl (Group M) (0.03-0.3 mg/kg-1 µg/kg)-based sedation, were included. Demographic variables, depth of sedation and recovery times were recorded. Sedation was administered by anesthetists blinded to the patient state index (PSI). Depth of sedation was measured and recorded with an EEG-based SEDLine monitor. PSI values at colonoscope insertion, removal, and at return of verbal responsiveness after colonoscope withdrawal were documented.
Results: Patients in Group P were younger (p<0.0001) and had lower ASA scores (p=0.02) than Group M patients. Group P patients experienced signiﬁcantly deeper degrees of sedation at all times and longer sedation and recovery times (p<0.0001 and p=0.01). Group P patients were more deeply sedated and had lower PSI values at the 5th minute (p<0.0001) and lower PSI scores after recovery (p<0.0001). Group M had more comorbidity but more stable PSI values. Their sedation levels were also closer to normal. 
Conclusions: Clinical signs for sedation showed that propofol was over-used. The titration of propofol using a processed-EEG monitor, such as SEDLine, can improve sedation procedures by reducing time spent in states of deep sedation/general anesthesia while maintaining the clinical advantages of propofol.

Do we use too much propofol for sedation in colonoscopy? Observational study with SedLine monitor