Estimation of median effective effect-site concentration (EC50) during target-controlled infusion of propofol for dilatation and curettage - A prospective observational study.

Background and Aims: Propofol is the drug of choice for sedation in daycare procedures due to its pharmacokinetic properties. Propofol delivery using target-controlled infusion (TCI) pump reduces adverse effects like hypotension and apnoea. In this study, we estimated the median effective effect-site concentration of propofol in patients undergoing dilatation and curettage.

Methods: Patients of the American Society of Anesthesiologists physical status class I-III, aged 40-70 years, undergoing elective dilatation and curettage were recruited for the study. All patients received 1 μg/kg fentanyl and 20 mg lignocaine. The first patient received an effect-site concentration of propofol at 4 μg/mL with TCI Schneider pharmacokinetic model. Failure was defined as patient movement at any time during the procedure. According to the 'BiasedCoin Design' up-and-down sequential method, the response of the previous patient determined the effect-site concentration of propofol of the next patient. The study was terminated once forty patients completed the procedures successfully. Probit analysis was used to determine EC50.

Results: Fifty-three patients were recruited for the study. The various effect-site concentrations of propofol EC50, EC90, and EC95 in providing sedation for dilatation and curettage were 3.38 μg/mL, 4.29 μg/mL, and 4.60 μg/mL, respectively. The incidence of hypotension and apnoea were comparable among the various concentrations of propofol. The mean duration of the propofol infusion was 20 ± 2.86 min. The time to recovery from propofol sedation was 6.97 ± 1.76 min.

Conclusion: A median effective effect-site concentration of 3.38 μg/mL of propofol is required to prevent patient movement during uterine dilatation and curettage.