Patient Maintained Sedation for Colonoscopy using a Target controlled infusion of Propofol

Fletcher G, Doherty P., Campbell L., Imrie G., Porteous C., Millar K.^* and Kenny G.⁺

Departments of Anaesthesia and Surgery, Royal Alexandra Hospital, Corsebar Road, Paisley PA2 9PN, UK. University Departments of Anaesthetics⁺ and Psychological Medicine^*, Glasgow University UK.

Background and Goal of Study: Target controlled propofol infusion (TCI) is used for sedation in anaesthetic practice and has been shown to have better psychomotor recovery than midazolam /morphine at 2 hours post colonoscopy.(1) In this study, TCI was modified to allow patient control and evaluated for safety and effectiveness in patients undergoing colonoscopy.

Materials and Methods: This was an open study of 20 patients. Local ethics committee approval was obtained. TCI was set initially at 1μg/ml. By double pressing a handset the patient could increase the TCI by 0.2μg/ml. The system had a lockout interval of 2 minutes and an upper limit of 4.5μg/ml. Heart rate, blood pressure, pulse oximetry and sedation score were recorded. Psychomotor testing using choice reaction times (CRT) was made prior to and 15 minutes after the sedation. A questionnaire post-sedation assessed patient satisfaction. Non parametric data are presented as median (interquartile range) and were analysed with the Wilcoxon Rank Sum test. Parametric data are presented as mean (+/- SD) and analysed using the Paired t test.

Results and Discussion: Colonoscopy was carried out successfully in all patients. The average age of the patients was 53.6 +/-10.2 years. The median maximum target propofol level was 2.7μg/ml (2.4,3.0). There were no episodes of desaturation or airway compromise. All patients were satisfied and none had recall of the colonoscopy. Four patients became oversedated, defined as being unresponsive, requiring manual over-ride of the system. Compared to pre-sedation measurements, propofol infusion caused a significant reduction in heart rate, 78.7+/-15 vs 69.8+/-13.5 (P<0.001 CI 4.67, 13.03) and in systolic blood pressure 121.1+/-13.2 mmHg vs 96.5+/-8.6 mmHg ( P<0.001 CI 18.8, 30.3). All patients were able to complete CRT testing 15 minutes after stopping propofol infusion. The median total increase in CRT was 162 msecs (-16, 383.3) which was statistically significant (P<0.05 95% CI 50, 343). Of note however was that 6 patients had a faster reaction time post colonoscopy.

Conclusions:

Patient controlled sedation with propofol is possible although in this model, oversedation was a problem in 4 out of 20 patients. There was a high level of patient and surgeon’s satisfaction. Patients had no recall, minimal cardiovascular effects and had a fast recovery.

Reference

1. Hay A, Black R et al. Psychomotor recovery after sedation for outpatient colonoscopy. European Journal of Anaesthesia 2001 18; supplement 21:16