Comparison of Dexmedetomidine and Esmolol for Induction of Controlled Hypotension in Spine Surgeries

Abstract

OBJECTIVEA comparative study to evaluate the efficacy of dexmedetomidine as a hypotensive agent in comparison to esmolol in Spine surgeries. METHODS60 patients ASA I or II scheduled for routine spine surgeries were equally randomly assigned to receive either dexmedetomidine or esmolol. In DEX group, patients received loading dose of 1 μg/kg dexmedetomidine diluted in 10 mL 0.9% saline infused over 10 min. before induction of anaesthesia, followed by continuous infusion of 0.5 μg/kg/h. In E group, patients received esmolol as a loading dose 1 mg/kg as 10 mL total vol. in saline infused over 1 min. followed by continuous infusion of 0.5 mg/kg/h. In both groups, aim was to maintain MAP within 55-65 mmHg. All patients were premedicated with IV glycopyrrolate 5 μg/Kg, IV midazolam 0.05 mg/kg and fentanyl 2 μg/kg. Patients received standard anaesthetic technique with propofol 2 mg/kg. Anaesthesia was maintained with O2, N2O, sevoflurane at 2 MAC and atracurium 0.1 mg/kg. Surgical field was assessed using Average Category Scale and average blood loss was calculated. Hemodynamic variables (MAP and HR); intraoperative fentanyl consumption; Emergence time and total recovery from anaesthesia (Aldrete score ≥9) were recorded. Sedation score was determined at 15, 30, 60 min. after tracheal extubation and time to first analgesic request was recorded. RESULTSBoth DEX group and E group reached the desired MAP (55-65 mmHg) with no intergroup differences in MAP or HR. The average category scale for quality of the surgical field in the range of MAP (55-65 mmHg) were <=2 with no significant differences between group scores during hypotensive period. The induction propofol dose was significantly lower in DEX group than E group (1.63±0.19 mg/kg) versus (2.00±0.05 mg/kg) respectively (P<0.000). Baseline values of MAP and HR were comparable in both groups. Mean intraoperative fentanyl consumption in DEX group was significantly less than E group (21.67±22.75 µg vs 77.17±27.85 µg). Emergence time and time to achieve ≥9 modified. Aldrete scores were significantly shorter in E group than DEX group .4.37±0.92 min. and 9.47±1.61 min. versus 8.5±1.9 min. and 4.95±1.24 min. (P<0.001). Incidence of intraoperative hypotension and bradycardia were seen in Esmolol group in 3.33 % cases. CONCLUSIONBoth dexmedetomidine and esmolol with sevoflurane are safe agents for controlled hypotension and are effective in providing ideal surgical field during spine surgeries. Compared with esmolol, dexmedetomidine offers the advantage of inherent analgesic, sedative and reduces dose of inducing agent.