Ropivacaine versus Bupivacaine-lidocaine Mixtures used in Peribulbar Blocks for Cataract Surgery: A Randomised, Triple-blind Clinical Study

Abstract

Introduction: Till recently, for providing anaesthesia for cataract surgeries peribulbar blocks were most commonly employed using various proportions of 0.5% bupivacaine and 2% lidocaine mixtures. As both these anaesthetic agents were reported to produce cardiovascular and Central Nervous System (CNS) side-effects, safer agents like levobupivacaine and ropivacaine are being introduced into clinical practice. Aim: To make a comparative evaluation of the characteristics of peribulbar blocks with 0.75% ropivacaine vis-à-vis the popularly used bupivacaine plus lidocaine mixtures. Materials and Methods: A randomised, single centre and triple-blind clinical study was undertaken between August 2021 and December 2021 comparing ropivacaine versus bupivacaine-lidocaine mixtures. A total of 90 patients attending the hospital for cataract surgeries were allocated into three groups of 30 each. Peribulbar blocks were given with 6 mL of 0.75% ropivacaine in group R, 6 mL of 1:1 mixture of 0.5% bupivacaine and 2% lidocaine in group BL, and 6 mL of 1:1 mixture of 0.5% bupivacaine and 2% lidocaine with adrenaline in groups BLA. The primary outcome measure was the total duration of analgesia (pain in the eye of grade >2). The secondary outcome measures studied were the time to onset of the motor and sensory blocks, the total analgesic requirement in the first 24 hours after surgery and changes in the Intraocular Pressures (IOP) after administration of the block. For statistical analysis, Analysis of Variance (ANOVA) and posthoc test of Tukey’s Honestly Significant Difference were used for parametric data and Chi-square test was used for non parametric data and a p-value of 0.05 was considered statistically significant. Results: The demographic characteristics and the baseline vital signs were comparable in all the three groups. Duration of the analgesia of the block was 4.2±0.79 hours, 3.6±1.08 hours, and 3.8±0.55 hours in groups R, BL and BLA, respectively. The total duration of analgesia was significantly longer in group R. The total analgesic consumption was 58.3 ±18.9, 75±25.42 and 68.3±24.5 and patients of group R had a significantly decreased consumption. There was a significant reduction in IOP in the patients of group R compared to other groups and the differences observed at 5 minutes,10 minutes and 25 minutes intervals were found to be statistically significant. Burning sensation in the eyes while injecting the drug for the peribulbar block was reported by 2, 10 and 12 patients, respectively in groups R, BL and BLA and the patients of group R were found to have less number of burning sensation episodes which was statistically significant (p-value=0.0084). More number of patients and surgeons in groups R had greater satisfaction levels. Conclusion: In peribulbar blocks, 6 mL of 0.75% ropivacaine produces satisfactory block characteristics with prolonged analgesia, reduced IOP, stable haemodynamics and optimal surgical operating conditions and patient satisfaction levels.

Keywords

• adrenaline
• intraocular pressure
• regional blocks