Jones J S, Plzak C, Wynn B N, Martin S
Department of Emergency Medicine, Butterworth Hospital, Grand Rapids, MI, USA.
Am J Emerg Med. 1998 Mar;16(2):117-20. doi: 10.1016/s0735-6757(98)90025-0.
To determine the effects of warming and buffering of 0.5% bupivacaine on the pain associated with intradermal injection and the time of onset of anesthesia, 40 adult volunteers were entered into a randomized, double-blind study conducted at a community teaching hospital. The three-part study compared room temperature (20 degrees) bupivacaine buffered to a pH of 7.1 with the following solutions: buffered bupivacaine warmed to 37 degrees C, unbuffered bupivacaine at room temperature, and unbuffered bupivacaine warmed to 37 degrees C. The same crossover protocol was followed for each part of the study. Subjects received 0.5-mL intradermal injections through 27-gauge needles over 30 seconds, one study solution in each forearm. Immediately after each injection, pain was assessed using a 100-mm visual analog pain scale. The time of onset of anesthesia (loss of intradermal sensation to pinprick) was measured by stopwatch. The mean perceived pain score for the warm buffered bupivacaine (51 mm) was significantly lower than for the room temperature buffered solution (63 mm, P = .003). Similarly, there was a statistical difference between the room temperature buffered and unbuffered solutions (65 v 78 mm, P < .001). The differences in mean pain scores for the room temperature buffered bupivacaine, compared with the other three solutions, suggest that warming and buffering have an additive effect. In this model, the latency of action of bupivacaine was not affected by alkalinization. However, warming bupivacaine to 37 degrees C reduced the time of onset to intradermal anesthesia by 12.1 seconds (95% confidence interval, 0.6 to 23.6). These results suggest that warming is more effective than buffering to reduce the pain of infiltration of bupivacaine and the time of onset of intradermal anesthesia.
为确定0.5%布比卡因的加温与缓冲对皮内注射相关疼痛及麻醉起效时间的影响，40名成年志愿者参与了在一家社区教学医院进行的随机双盲研究。这项三部分的研究将室温（20摄氏度）下pH值缓冲至7.1的布比卡因与以下溶液进行了比较：加温至37摄氏度的缓冲布比卡因、室温下的未缓冲布比卡因以及加温至37摄氏度的未缓冲布比卡因。研究的每个部分都遵循相同的交叉方案。受试者通过27号针头在30秒内接受0.5毫升皮内注射，每只前臂注射一种研究溶液。每次注射后立即使用100毫米视觉模拟疼痛量表评估疼痛。通过秒表测量麻醉起效时间（对针刺皮内感觉丧失）。加温缓冲布比卡因的平均疼痛评分（51毫米）显著低于室温缓冲溶液（63毫米，P = 0.003）。同样，室温缓冲溶液与未缓冲溶液之间存在统计学差异（65对78毫米，P < 0.001）。与其他三种溶液相比，室温缓冲布比卡因的平均疼痛评分差异表明加温和缓冲具有叠加效应。在该模型中，布比卡因的作用潜伏期不受碱化影响。然而，将布比卡因加温至37摄氏度可使皮内麻醉的起效时间缩短12.1秒（95%置信区间，0.6至23.6）。这些结果表明，加温在减轻布比卡因浸润疼痛及皮内麻醉起效时间方面比缓冲更有效。
