Comparison of Soda Bicarbonate and Hyaluronidase as an Adjuvant to Bupivacaine in Supraclavicular Brachial Plexus Block: A Double Blinded Randomised Clinical Study

Introduction: For upper limb surgeries, brachial plexus nerve blocks with additives offer efficient analgesia and prolonged regional block. Hyaluronidase is an enzyme, which catalyses the hyaluronan and lowers its viscosity, improving tissue permeability of Local Anaesthetics (LA) to accelerate their dispersion and distribution. Adjuvant sodium bicarbonate raises the pH of the LA, improving tourniquet tolerance, resulting in greater analgesia quality, early onset and longer duration of sensory and motor blockade. Aim: The aim of this study was to compare the effects of soda bicarbonate and hyaluronidase as an adjuvant to bupivacaine in Supraclavicular Brachial Plexus Block (SBPB). Materials and Methods: The present double blinded randomised clinical study was conducted in a tertiary care hospital on 40 patients undergoing elective upper limb surgeries under Peripheral Nerve Stimulator (PNS) guided - SBPB. In addition to inj. bupivacaine 0.5% 18 mL + inj. lignocaine with adrenaline 2% (1:200000) 10 mL, Group S (n=20) received inj. soda bicarbonate 7.5% w/v 1 mL and Group H (n=20) received inj. hyaluronidase 900IU 1 mL - a total 29 mL. The onset time, duration of sensory and motor blockade were recorded. Rescue analgesia was recorded at 0, 1, 3, 5, 7, and 10 hours. Categorical variables were analysed using the Chi-square test. To analyse continuous variables, the student’s t-test was used. The p-value of less than 0.05 was taken to be statistically significant. Results: The demographic data were comparable in both the groups. Time of sensory block in Group H was 2.1±0.8 minutes and in Group S was 2.7±0.4 minutes, p<0.05. The onset for motor block in both groups was comparable. Duration of sensory and motor blockade were 399.5±26.35 minutes; 376.25 ±26.60 minutes and 270.75±35.22 minutes; 251.75±34.23 minutes, while time of rescue analgesia was 354.00±26.98 and 223.00±41.75 minutes in Group S and Group H, respectively, p<0.05. VAS was comparable, but at five and seven hours 45%; 55% and 100%; 0% received rescue analgesia in Group S and Group H, respectively, p<0.05. No major adverse effects were noticed. Conclusion: Addition of hyaluronidase as an adjuvant causes faster onset of block, with minimal/no side effects, earlier postoperative mobilisation in comparison to soda bicarbonate. Duration of analgesia is more with soda bicarbonate compared to hyaluronidase.