皮肤温度用于评估超声引导下小儿臂丛神经阻滞麻醉效果的可行性

Feasibility of skin temperature in evaluating the efficacy of ultrasound-guided brachial plexus block in children

目的研究小儿臂丛神经阻滞后皮肤温度变化及其对臂丛神经阻滞效果的评估价值。方法选择择期行肱骨髁上骨折切开复位内固定的患儿30例,喉罩全身麻醉后在超声引导下用0.33%罗哌卡因行腋路臂丛神经阻滞。在入手术室后(T_0)、全身麻醉后(T_1),以及神经阻滞后0min(T_2)、5min(T_3)、10min(T_4)、15min(T_5)、20min(T_6)各时间点,测定患侧和健侧第一掌骨外侧的皮肤温度。在T_0、T_1、T_4、T_6、切皮(T_7)、手术结束(T_8)和出麻醉后监测治疗室(T_9)各时间点,记录平均动脉压(MAP)和心率。术后4、6、8、12、16h采用小儿疼痛VAS评分评估疼痛程度。计算用皮肤温度变化评估阻滞效果的灵敏度、特异度、阳性预测值、阴性预测值,以及阳性和阴性似然比。阻滞后15min时双手皮肤温度差≥1℃为皮肤温度变化阳性,术后4h疼痛VAS评分<3分为阻滞有效。结果 T_0至T_2时间点,患侧与健侧第一掌骨外侧的皮肤温度间差异均无统计学意义(P值均>0.05);臂丛神经阻滞后,患侧第一掌骨外侧的皮肤温度明显升高,T_3至T_6时间点均显著高于健侧(P值均<0.01);健侧第一掌骨外侧的皮肤温度在患侧臂丛神经阻滞前后无明显变化。与T_0时间点比较,T_1、T_4、T_6至T_9时间点的MAP和心率均显著降低(P值均<0.05);全身麻醉后各时间点间MAP和心率的差异均无统计学意义(P值均>0.05)。患儿术后12和16h的疼痛VAS评分均显著高于术后4h(P值均<0.05)。用皮肤温度变化评估阻滞效果的灵敏度为96%,特异度为67%,阳性预测值为92%,阴性预测值为80%,阳性似然比为2.9,阴性似然比为0.06。结论小儿臂丛神经阻滞后5min阻滞侧第一掌骨外侧皮肤温度即升高,约15min达最大值。这种皮肤温度升高可作为评估小儿神经阻滞效果的一种简单、有效的方法,有助于患儿术中和术后的镇痛管理。

Objective To investigate the skin temperature response after brachial plexus block and its value in evaluating the effect of brachial plexus block in children. Methods Thirty children suffering from supracondylar fracture of humerus and undergoing open reduction and internal fixation were enrolled in this study. The children received an ultrasound-guided axillary brachial plexus block with 0.33% ropivacaine after general anesthesia with a laryngeal mask. Skin temperature of the lateral part of the first metacarpal bone in both hands was measured while entering the operating room （To）, after general anesthesia （T1）, 0 min （T2）, 5 min （T3）, 10 min （T4）, 15 min （T5） and 20 min （T6） after nerve block. Mean arterial pressure （MAP） and heart rate were detected at T0, T1, T4, T6, skin incision （TT）, the end of surgery （T8） and out of post-anesthesia care unit （Tg）. Visual analog scale （VAS） scores for pain were recorded at 4, 6, 8, 12 and 16 h after surgery. The sensitivity, specificity, positive predictive value, negative predictive value, positive and negative likelihood ratio were calculated, assuming VAS scores 〈3 at 4 h after the surgery was the effective block and skin temperature difference between hands ≥ 1℃ at 15 min after nerve block was positive. Results There was no significant difference in skin temperature between injured hand and healthy hand at To, T1 and T2 （all P〉0.05）. The skin temperature of the injured hand was significantly higher that of healthy hand at T3, T4, T5 and T6 （all P〈0. 01 ）. There was no significant difference in skin temperature of healthy hand before and after nerve block. Compared with those at To, MAP and heart rate decreased significantly at T1 ,T4 ,T6 to T9 （all P〈0. 05）, but there was no significant difference in MAP or heart rate among the time points after general anesthesia （all P〉0.05）. VAS scores at 12 h and 16 h postoperatively were significantly higher than that at 4 h postoperatively （both P〈0. 05）. When skin temperature was used to predict the block efficacy in children, it had a sensitivity of 96%, a specificity of 67%, a positive predictive value of 92% and a negative predictive value of 80%; positive and negative likelihood ratio were 2.9 and 0.06, respectively. Conclusion Skin temperature of the injured hand increases at 5 min and reaches its maximum at 15 min after brachial plexus block, which can be used as a simple and effective method to evaluate the effect of nerve block in children and is helpful for the intraoperative and postoperative analgesia management of children.