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 standardised 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.