The effects of intravenous dexmedetomidine on spinal anesthesia: comparision of different dose of dexmedetomidine

Abstract

BackgroundIn 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.MethodsSixty 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.ResultsThe 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.ConclusionsBoth 0.5 and 1.0 ug/kg of dexmedetomidine administered as isolated boluses in the absence of maintenance infusions prolonged the duration of spinal anesthesia.

Role of Intravenous Dexmedetomidine in Prolonging Postoperative Analgesia and Quality of Block Following Spinal Anaesthesia. A Systemic Review and Update

“…Some studies have reported higher level of sensory-motor blockade of hyperbaric bupivacaine by the use intravenous dexmedetomidine [30,31,33,35,43] whereas, in study using low dose intravenous dexmedetomidine as sedative agent after spinal anaesthesia reported no difference in block characteristic by dexmedetomidine [36]. Lee et al [12] using two different dose of dexmedetomidine (0.5 mcg/kg Vs 1 mcg/kg) reported higher level of sensory block in both group of dexmedetomidine in comparison to placebo. Abdallah et al [27] did quantitative analysis in a meta-analysis after collecting data from the studies showing higher sensory block, but they failed to see any statistically significant increase in height of block by use of dexmedetomidine.…”

“…The timing and dosing method of intravenous dexmedetomidine in spinal anaesthesia varies in different study. Commonly used method of intravenous dexmedetomidine is either as loading dose just before or after spinal anaesthesia [12,[27][28][29][30][31][32], loading dose followed by continuous infusion [11,[33][34][35][36]. Most commonly used loading dose is 0.5 mcg/kg to 1 mcg/kg over 10 min and infusion dose range from 0.2 mcg/kg/hr to 1 mcg/kg/hr [25,26].…”

“…Most of these studies and meta-analysis has shown that intravenous dexmedetomidine given just before or after spinal anaesthesia improved the quality and duration of spinal block [12,[27][28][29][30][31][32][33]. there are many variation in the dosing and method of administration, so it challenging to reliably translate the result into clinical practice.…”

“…Few studies have evaluated the onset time of sensory block after spinal anaesthesia, Readdy et al have compared intravenous dexmedetomidine with clonidine reported that dexmedetomidine shortened onset of sensory-motor block [41] but other studies are not supporting the faster onset of sensory/motor block [12,13,[27][28][29][30]. Few study have reported intravenous dexmedetomidine shortened the onset time by 30-60 sec, which might be clinically significant but it was insignificant statistically [11,33,35].…”

“…The different potential role of intravenous dexmedetomidine in neuraxial anaesthesia has not been evaluated fully, few studies have shown that it prolong the sensory-motor blockade and provide better intraoperative and postoperative analgesia [12,13]. Apart from prolonging analgesia, it has been used for prevention and treatment of shivering [14][15][16][17][18][19][20][21][22][23].…”