Department of Anesthesia and Critical Care Medicine, Cairo University, 1 Alsaraya Street, Almanyal, Cairo 11559, Egypt.
Department of Critical Care, El-Ameen Hospital, Taif, Saudi Arabia.
Br J Anaesth. 2017 Aug 1;119(2):276-280. doi: 10.1093/bja/aex166.
Supraclavicular nerve block is a popular approach for anaesthesia for upper limb surgeries. Conventional methods for evaluation of block success are time consuming and need patient cooperation. The aim of this study was to evaluate whether the perfusion index (PI) can be used to predict and provide a cut-off value for ultrasound-guided supraclavicular nerve block success.
The study included 77 patients undergoing elective orthopaedic procedures under ultrasound-guided supraclavicular nerve block. After local anaesthetic injection, sensory block success was assessed every 3 min by pinprick, and motor block success was assessed every 5 min by the ability to flex the elbow and the hand against resistance. The PI was recorded at baseline and at 10, 20, and 30 min after anaesthetic injection in both blocked and non-blocked limbs. The PI ratio was calculated as the PI after 10 min divided by the PI at the baseline. Receiver operating characteristic curves were constructed for the accuracy of the PI in detection of block success.
The PI was higher in the blocked limb at all time points, and this was paralleled by a higher PI ratio compared with the unblocked limb. Both the PI and the PI ratio at 10 min after injection showed a sensitivity and specificity of 100% for block success at cut-off values of 3.3 and 1.4, respectively.
The PI is a useful tool for evaluation of successful supraclavicular nerve block. A PI ratio of > 1.4 is a good predictor for block success.
锁骨上神经阻滞是上肢手术麻醉的一种常用方法。评估阻滞成功的传统方法既耗时又需要患者配合。本研究旨在评估灌注指数（PI）是否可用于预测和提供超声引导锁骨上神经阻滞成功的截止值。
该研究纳入了 77 例行超声引导锁骨上神经阻滞的择期骨科手术患者。局部麻醉注射后，每 3 分钟通过针刺评估感觉阻滞成功，每 5 分钟通过肘部和手部对抗阻力弯曲的能力评估运动阻滞成功。在麻醉注射后 10、20 和 30 分钟，分别在阻滞侧和非阻滞侧记录 PI。PI 比值计算为 10 分钟后的 PI 除以基线时的 PI。构建 PI 检测阻滞成功的准确性的受试者工作特征曲线。
在所有时间点，阻滞侧的 PI 均较高，与未阻滞侧相比，PI 比值也较高。注射后 10 分钟的 PI 和 PI 比值的截断值分别为 3.3 和 1.4 时，对阻滞成功的灵敏度和特异性均为 100%。
PI 是评估锁骨上神经阻滞成功的有用工具。PI 比值>1.4 是阻滞成功的良好预测指标。
