Rai Arati, Bhutia Meyong Pincho
Assistant Professor, Department of Anaesthesia, Sikkim Manipal Institute of Medical Science, Gangtok, Sikkim, India.
J Clin Diagn Res. 2017 Apr;11(4):UC09-UC12. doi: 10.7860/JCDR/2017/26241.9654. Epub 2017 Apr 1.
Use of dexmedetomidine as an additive to spinal anaesthesia is gaining popularity; but there seems to be no clear consensus on the ideal dose to be used. Because of dose related prolongation of duration of motor blockade along with increase in the incidence of side effects of dexmedetomidine namely hypotension and bradycardia, use of higher doses is not recommended.
To evaluate the efficacy of two different doses of dexmedetomidine (3 μg and 5 μg) given in combination with 0.5% hyperbaric bupivacaine via intrathecal route with regard to the quality of anaesthesia namely the time to attain highest sensory and motor blockade, side effects of dexmedetomidine and time to first rescue analgesia.
Sixty American Society of Anaesthesiologist (ASA) Grade I and II orthopaedic patients undergoing lower limb surgeries between the ages of 20-60 years and height >150 cm were randomly divided into two groups of 30 patients each: Group D3 to receive 3 μg of Inj. Dexmedetomidine (0.5 ml, reconstituted using normal saline) along with 12.5 mg (2.5 ml) of 0.5% hyperbaric bupivacaine and Group D5 to receive 5 μg of inj. Dexmedetomidine (0.5 ml, reconstituted using normal saline) along with 12.5 mg (2.5 ml) of 0.5% hyperbaric bupivacaine keeping the total volume of study drug constant in all 60 patients (3 ml). Data recordings were done for time to reach best sensory and motor block, intraoperative haemodynamic changes and time to first postoperative rescue analgesia. Statistical analysis was done using student's t-test and Chi-square test with p-value of <0.05 considered to be significant.
The two groups analysed were similar in terms of demographic profile, time to reach highest sensory block (T10) dermatome, time to reach Bromage scale 4, time to surgical incision after spinal and the total duration of surgery (p>0.05). The change in haemodynamics was similar (p>0.05). A statistically significant difference (p<0.001) was observed in time to first rescue analgesia after skin closure with Group D3 having 206.47 minutes while in Group D5 the time was 271.33 minutes.
Used in a dose of 5 μg (in 0.5 ml volume) as an additive in spinal anaesthesia maximal beneficial effect of dexmedetomidine can be obtained without any side effects.
右美托咪定作为脊髓麻醉的添加剂使用越来越普遍；但对于理想使用剂量似乎尚无明确共识。由于右美托咪定与运动阻滞持续时间延长相关，且其副作用（即低血压和心动过缓）的发生率增加，不建议使用高剂量。
评估两种不同剂量（3μg和5μg）的右美托咪定与0.5%重比重布比卡因经鞘内途径联合使用时，在麻醉质量方面（即达到最高感觉和运动阻滞的时间、右美托咪定的副作用以及首次补救镇痛的时间）的效果。
60例年龄在20 - 60岁、身高>150cm、美国麻醉医师协会（ASA）分级为I级和II级的接受下肢手术的骨科患者被随机分为两组，每组30例：D3组接受3μg右美托咪定注射液（0.5ml，用生理盐水复溶）与12.5mg（2.5ml）0.5%重比重布比卡因；D5组接受5μg右美托咪定注射液（0.5ml，用生理盐水复溶）与12.5mg（2.5ml）0.5%重比重布比卡因，使所有60例患者研究药物的总体积保持恒定（3ml）。记录达到最佳感觉和运动阻滞的时间、术中血流动力学变化以及首次术后补救镇痛的时间。采用学生t检验和卡方检验进行统计分析，p值<0.05被认为具有统计学意义。
分析的两组在人口统计学特征、达到最高感觉阻滞（T10）皮节的时间、达到布罗麻量表4级的时间、脊髓穿刺后至手术切口的时间以及手术总时长方面相似（p>0.05）。血流动力学变化相似（p>0.05）。皮肤缝合后首次补救镇痛的时间存在统计学显著差异（p<0.001），D3组为206.47分钟，而D5组为271.33分钟。
在脊髓麻醉中作为添加剂使用剂量为5μg（0.5ml）时，可获得右美托咪定的最大有益效果且无任何副作用。
