Effect of Single Dose Pre-induction Dexmedetomidine on Anaesthetic Requirement and Pain Profile in Orthopaedic Surgery: A Placebo-controlled Double Blind Randomised Controlled Trial

Abstract

Introduction: Dexmedetomidine, a selective α2-adrenoreceptor agonist is an important adjuvant to general anaesthetic practice in view of its potent sedative, anaesthetic-sparing and analgesic effects. We investigated the effect of a single dose pre–induction dexmedetomidine on the anaesthetic requirement during surgery and pain profile. Methods: 60 patients who were ASA I - II and planned for orthopaedic procedures under general anaesthesia were recruited. Patients were randomized into 2 groups: Group D received intravenous (IV) dexmedetomidine 1 µg/ kg (n=30) preoperatively or Group P received normal saline (n=30) instead. Both groups were induced with stan- dardised IV induction agents and anaesthesia maintained with Sevoflurane, titrated using the bispectral index scale. The expired fraction of sevoflurane and haemodynamic parameters were recorded at 5-minute intervals intraoperatively. Postoperatively, postoperative pain score (VAS) was documented at 30 minutes recovery. Results: Our study showed a 27.8% reduction in the intraoperative expired fraction of sevoflurane requirement in group D versus 11.5% reduction in Group P (p < 0.001) and a lower mean heart rate in Group D as compared to Group P [mean (CI): 69.20 (64.03, 74.37) versus 82.00 (72.12, 91.87) per minute, p = 0.00]. The mean (SD) VAS for 30 minutes postoperative pain was significantly lower in group D when compared to group P [1.507 (0.275) vs 2.209 (0.403), p = 0.00]. Conclusion: This study has shown that a single dose of pre-induction dexmedetomidine was able to significantly reduce anaesthetic requirement of sevoflurane and mean heart rate intraoperatively and postoperative pain.