Effectiveness of 0.125% Bupivacaine versus 0.125% Ropivacaine in Epidural Labour AnalgesiaA Randomised Clinical Study

Abstract

Introduction: Epidurally administered local anesthetics provide most effective analgesia during labour process. Among the available local anesthetics Bupivacaine and ropivacaine are the most commonly used drugs in concentrations ranging from 0.0625% to 0.125% and 0.08% to 0.125%, respectively. Both these drugs are weak bases, highly protein bound, highly lipid soluble, and have a pKa of 8.1, low unionised fraction, thus having a slightly longer time for onset of action but with a longer duration of action and have less transfer across the placenta. Hence, they are ideal drugs for use in labour analgesia. Aim: To compare the effectiveness of programmed intermittent bolus of 0.125% bupivacaine and 0.125% ropivacaine in low volumes in full term primigravidas for epidural labour analgesia. Materials and Methods: This randomised clinical study was conducetd at PES Institute of Medical Sciences and Research, Kuppam, Andhra Pradesh, India, between June 2020 and December 2021 among 80 full term primi parturients requiring normal vaginal delivery. They were randomly divided into two groups of 40 each. Group B received 10 mL of 0.125% bupivacaine and group R received 10 mL of 0.125% ropivacaine as initial bolus dose. Repeat doses of 5 mL was given every 60 minutes or when the patient had Visual Analogue Score (VAS) score >4 with a maximum dose of 10 mL/hr with a 20 minute interval between two doses. Parameters assessed were onset, duration, level and quality of analgesia, motor blockade, number of epidural top ups, total volume of drug consumed, mode of delivery, duration of labour, APGAR score, haemodynamics, patient satisfaction and complications. Data was entered in Microsoft Excel 2010 version and analysed using Statistical Package for Social Sciences (SPSS) version 20.0. Results: Both drugs were equally effective in terms of analgesia, maternal and foetal outcomes. Bupivacaine had a faster onset of action (7.075±0.916 min) compared to ropivacaine (8.225±0.891 min) (p-value=0.001). Ropivacaine had a shorter duration of action (43.1±2.30 min vs. 47.9±4.16 min in group B) (p-value=0.0001), requiring more top-up doses (5.2±0.46 versus 4.77±0.61 in group B) (p-value=0.0007), and more total volume of drug (38.5±3.08 mL versus 35.5±4 mL in group B) (p-value=0.002). It also caused lesser motor blockade (Bromage score of 1 in 1 parturient vs. 8 parturients in group B) (p-value=0.0129) and better overall maternal satisfaction score (excellent) in 30 parturients versus 25 parturients in group B. APGAR scores at 1 minute and 5 minutes were comparable between the two groups. Mean heart rates, mean blood pressures were also comparable between the two groups. There were no significant adverse effects in either groups. Conclusion: By providing minimal motor blockade and adequate analgesia 0.125% ropivacaine allows parturients to go through the labour process with excellent maternal satisfaction and minimal adverse effects compared to 0.125% bupivacaine