Comparative study of bupivacaine-lignocaine to bupivacaine-lignocaine-dexamethasone in providing postoperative analgesia in interscalene block for shoulder arthroscopy

Abstract

Interscalene brachial plexus block has gained prominence nowadays and has benefits of lesser intraoperative anaesthetic use, lesser analgesic requirement and lesser incidence of postoperative nausea and vomiting. Adjuvants are added to local anaesthetics for prolonging postoperative analgesia with interscalene block. Among the adjuvants, dexamethasone has been used extensively in past decade in neuraxial and peripheral nerve blocks. The aim of the study was to compare the duration of postoperative analgesia with lignocaine- bupivacaine combination and dexamethasone added to lignocaine - bupivacaine in interscalene block for shoulder arthroscopy. In this comparative study, 48 patients of ASA grade I and II were selected and divided into 2 groups of 24 each. After obtaining informed written consent, general anaesthesia was given to patients satisfying inclusion criteria and ultrasound guided interscalene block was performed. Time of demand for additional analgesic supplementation by the patient were noted. Hemodynamic and respiratory monitoring were done to assess any side effects and complications.Duration of analgesia was prolonged in group II (10.33±1.45 hours) i.e in lignocaine-bupivacaine-dexamethasone group than Group I(7.17±0.87 hours) i.e in lignocaine-bupivacaine group with p value less than 0.001. There were no significant differences between the two groups in secondary outcomesbased on hemodynamic parameters. Dexamethasone at a dose of 8 mg in addition to lignocaine-bupivacaine, given perineurally in interscalene block provided better quality of block and prolonged duration of analgesia by almost 3 hours, without any significant changes in hemodynamic parameters. There were no major adverse effects noted.