In this prospective, randomized, double-blind, placebo-controlled trial, we tried to find out appropriate amounts of single-dose dexmedetomidine to prolong the duration of spinal anesthesia in a clinical setting.
Sixty patients who were scheduled for unilateral lower limb surgery under spinal anesthesia were randomized into three groups receiving normal saline (control group, n = 20) or 0.5 or 1.0 ug/kg dexmedetomidine (D-0.5 group, n = 20; D-1, n = 20) intravenously prior to spinal anesthesia with 12 mg of bupivacaine. The two-dermatome pinprick sensory regression time, duration of the motor block, Ramsay sedation score (RSS), and side effects of dexmedetomidine were assessed.
The two-dermatome pinprick sensory regression time (57.6 ± 23.2 vs 86.5 ± 24.3 vs 92.5 ± 30.7, P = 0.0002) and duration of the motor block (98.8 ± 34.1 vs 132.9 ± 43.4 vs 130.4 ± 50.4, P = 0.0261) were significantly increased in the D-0.5 and D-1 groups than in the control group. The RSS were significantly higher in the D-0.5 and D-1 groups than in the control group. However, there were no patients with oxygen desaturation in dexmedetomidine groups. The incidences of hypotension and bradycardia showed no differences among the three groups.