Effect of dexmedetomidine on brachial plexus block with ropivacaine and upper extremity ischemia-reperfusion injury in patients undergoing upper extremity surgery / 中华麻醉学杂志

ABSTRACT

Objective To investigate the effect of dexmedetomidine on brachial plexus block with ropivacaine and upper extremity ischemia-reperfusion (I/R) injury in patients undergoing upper extremity surgery. Methods Forty ASA Ⅰ or Ⅱ patients of both sexes, aged 18-55 yr, weighing 45-80 kg, scheduled forupper extremity surgery under brachial plexus block, were randomly divided into 2 groups ( n = 20 each) control group ( group C )and dexmedtomidine group (group D). In group C, brachial plexus block was performed using 0.5% ropivacaine 30 ml. In group D, brachial plexus block was performed with a mixture (30 ml) of 0.5% ropivacaine and 8 mg dexmedetomidine. The efficacy of motor and sensory block was evaluated and the onset time and duration of motor and sensory block were recorded. Venous blood samples were obtained from peripheral vein on the operated side before anesthesia induction (T0), and at 1, 5 and 30 min after tourniquet release (T1-3) to detect the plasma concentrations of MDA and ischemia-modified albumi (IMA). Arterial blood samples were also obtained at the same time points for blood gas analysis. The complications such as nausea and vomiting, respiratory depression, bradycardia and dizziness were recorded. Sufentanil 0.2 μg/kg was given as rescue medication. If the operation could not be completed, general anesthesia was used. Results There was no requirement for rescue analgesics and general anesthesia, and no complications occurred in all the patients. The duration of sensory and motor block was significantly longer, the plasma concentrations of MDA and IMA were significantly lower, and PaO2 and BE were significantly higher in group D than in group C ( P ＜ 0.05). The plasma concentrations of MDA and IMA were significantly higher at T2 and T3 in both groups, the pH value was significantly lower at T1 in group C, PaO2 at T1 and BE at T1 and T2 were significantly lower in both groups than those at T0 ( P ＜ 0.05). Conclusion Dexmedetomidine can not only enhance the efficacy of brachial plexus block with ropivacaine, but also reduce the upper extremity I/R injury caused by tourniquet in patients undergoing upper extremity surgery.