Randomized Open-Labelled Comparative Evaluation of the Efficacy of Nitroglycerine, Esmolol and Dexmedetomidine in Producing Controlled Hypotension in Spine Surgeries.

Aim: This study was designed to evaluate the efficacy of nitroglycerine (NTG), esmolol, and dexmedetomidine (DEX) as hypotensive agents in decreasing intraoperative blood loss by producing controlled hypotension in posterior spine surgeries.

Materials and Methods: Sixty patients aged 18-60 years, the American Society of Anesthesiologists physical status Classes I and II of either gender, were randomly assigned into three groups to receive either: NTG (0.01%) at the rate of 3-10 μg.kg-1 .min-1 after positioning without a prior loading dose in Group N, esmolol 500 μg.kg-1 loading dose over 1 min before induction of anesthesia followed by 50-300 μg.kg-1 .min-1 infusion in Group E, and DEX 1 μg.kg-1 over 10 min before induction followed by 0.2-0.7 μg.kg-1 .h-1 . infusion in Group D to maintain mean arterial blood pressure (MAP) between 60 and 65 mmHg. The three groups were compared for the achievement of target MAP, intraoperative blood loss, reversibility of hypotensive state, quality of surgical field, emergence time, and postextubation sedation score.

Statistical Analysis: Analysis of variance was used for intergroup analysis, and for multiple comparisons, Bonferroni post hoc test was applied. P < 0.05 was considered statistically significant.

Results: Patients in Group D and Group E achieved the target MAP with better heart rate control as compared to Group N. The intraoperative blood loss was significantly lesser in Group D ( P < 0.001). The time to hypotension reversal and emergence time was prolonged in Group D ( P < 0.001). The mean quality of surgical field score was statistically insignificant among the three groups. The mean Ramsay Sedation Scores were significantly higher in Group D compared to Groups N and E at 20th and 40th min postextubation ( P < 0.001) with no significant intergroup difference at 60th min postextubation ( P = 0.130).

Conclusion: Continuous infusion of DEX is an effective and safe method of producing controlled hypotension by achieving the target MAP, minimizing blood loss, and maintaining superior hemodynamics in comparison with NTG and esmolol in posterior spine surgeries.