Comparison of Prolongation of Spinal Anesthesia Produced by Intravenous Dexmedetomidine and Midazolam: A Randomized...

Various intravenous (i.v.) adjuvants have been used along with spinal anesthesia to delay the onset of postoperative pain.

To compare effects of i.v. dexmedetomidine with midazolam on duration of spinal anesthesia.

This prospective randomized control trial was conducted in a tertiary care institution.

Forty-three patients presenting for elective infraumbilical surgery under spinal anesthesia were randomly allocated into two groups. Group A received a loading dose of 0.5 μg/kg followed by 0.5 μg/kg/h of i.v. dexmedetomidine. Group B received a loading dose of 0.03 mg/kg followed by 0.03 mg/kg/h of i.v. midazolam. Two dermatomal regressions, regression to S₁ level, and sedation score were noted.

To test the statistical significance of duration of sensory blockade, Mann-Whitney U-test was applied. The incidence of bradycardia and hypotension was analyzed using Pearson's correlation coefficient test.

The mean time for two dermatomal regressions was significantly prolonged in Group A (2.3 ± 0.4 h) than Group B (1.6 ± 0.5 h, P = 0.001). Mean time for sensory regression to S₁ dermatome was also prolonged in Group A (5.2 ± 0.83 h) than in Group B (4.4 ± 0.87 h, P = 0.01). Glycopyrrolate was administered in 45% of patients in Group A and 21% in Group B, which was statistically significant (P = 0.039).

Conscious sedation with i.v. dexmedetomidine at a loading dose of 0.5 μg/kg followed by 0.5 μg/kg/h prolongs duration of spinal anesthesia than i.v. midazolam at a loading dose of 0.03 mg/kg followed by 0.03 mg/kg/h in patients undergoing infraumbilical surgeries. However, dexmedetomidine is associated with higher incidence of hemodynamic instability.