Effect of preoperative intranasal dexmedetomidine on characteristics of spinal anesthesia with hyperbaric bupivacaine for lower limb orthopedic surgery: a double-blinded randomized control study.

Introduction: Dexmedetomidine is administered intravenously, intrathecally, and intramuscularly to enhance the effect of subarachnoid anesthesia. In this study, we investigated the effect of intranasal dexmedetomidine on the characteristics of spinal anesthesia.

Material and methods: In this double-blinded randomized control study, 60 patients undergoing orthopedic surgery under spinal anesthesia were allocated to two groups. Group A received intranasal dexmedetomidine 1 μg kg^-1 20 minutes (min) before the subarachnoid block. Group B received intranasal normal saline 20 min before the subarachnoid block. Time for the onset of sensory and motor blockade, two-segment regression time, and request of first rescue analgesia were noted. Sedation scores using the Ramsay Sedation Scale (RSS), adverse effect and hemodynamic parameters were assessed.

Results: The onset of sensory block and motor block did not differ significantly between the groups. However, two-segment regression time was significantly longer in Group A than in Group B (113.17 ± 14.11 min vs. 94.13 ± 9.59 min, respectively; P < 0.001), and the time for first rescue analgesia was significantly longer in Group A than in Group B (3.97 ± 1.56 min vs. 2.56 ± 0.76 min, respectively; P < 0.001). The overall mean heart rate and mean arterial pressure were comparable between the two groups with stable hemodynamics. The visual analogue scale score in Group A was low (P < 0.001). Intraoperatively, at 30 min and 60 min, the change in RSS score was found to be statistically significant (P < 0.001).

Conclusions: Intranasal dexmedetomidine prolongs the effect of subarachnoid anesthesia, provides stable hemodynamics with arousable sedation, and offers a noninvasive, better-tolerated alternative compared to other invasive routes of administration.