Equal mixture of 2% lidocaine with adrenaline and 0.5% bupivacaine 20 mL provided faster onset of complete conduction blockade during ultrasound-guided supraclavicular brachial plexus block than 20 mL of 0.5% bupivacaine alone: a randomized double-blinded clinical trial.

INTRODUCTION: Recent evidence has questioned the advantage of local anesthetic (LA) combinations. This study tested the hypothesis that mixing rapid-onset (lidocaine) and long-duration (bupivacaine) LA would provide faster onset of complete conduction blockade (CCB) compared with bupivacaine alone and longer duration of analgesia compared with lidocaine alone during low-volume (20 mL) ultrasound-guided (USG) supraclavicular brachial plexus block (SCBPB). METHODS: Sixty-three patients receiving USG-SCBPB were randomly allocated into: group L: 20 mL 2% lidocaine with epinephrine 1:200 000; group B: 20 mL 0.5% bupivacaine; group LB: 20 mL of equi-volume mixture of both drugs. Sensory and motor blockade was recorded on a three point sensory and motor assessment scale at 10 min intervals for up to 40 min and the total composite score (TCS) at each time point was determined. The duration of analgesia was also noted. RESULTS: The mean time to CCB of group LB (16±7 min) was comparable (p>0.05) with group L (14±6 min) and group B (21±8 min) in patients who were attained CCB. However, the proportion of patients attaining complete conduction block (TCS=16/16) was significantly lower (p=0.0001) in group B (48%) when compared with group L (95%) and group LB (95%) at the end of 40 min. The median (IQR) duration of postoperative analgesia was longest in group B; 12.2 (12-14.5) hours, followed by group LB 8.3 (7-11) hours and 4 (2.7-4.5) hours in group L. CONCLUSION: At 20 mL LA volume, equal mixture of lidocaine and bupivacaine provided significantly faster onset of CCB compared with bupivacaine alone and longer duration of postoperative analgesia compared with lidocaine alone but shorter than bupivacaine alone during low-volume USG-SCBPB. TRIAL REGISTRATION NUMBER: CTRI/2020/11/029359.

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.