Krishnan S K, Benzon H T, Siddiqui T, Canlas B
Department of Anesthesiology, Northwestern University Medical School, 251 East Huron St., Chicago, IL 60611-2908, USA.
Reg Anesth Pain Med. 2000 Nov-Dec;25(6):615-9. doi: 10.1053/rapm.2000.8933.
We wished to determine which long-acting local anesthetic would produce the least pain on injection for treatment of myofascial pain disorders. We compared the pain on intramuscular injection of bupivacaine, ropivacaine, bupivacaine with dexamethasone, ropivacaine with dexamethasone, and needle placement alone.
Thirty volunteers received 5 injections each: (1) needle only, (2) bupivacaine 0.5%, (3) ropivacaine 0.5%, (4) bupivacaine 0.5% with dexamethasone 0.13 mg/mL, and (5) ropivacaine 0.5% with dexamethasone 0.13 mg/mL. The injections were made in the volunteers' upper trapezius muscles; there was a 15-minute interval between injections. The sequence of injections was randomized by Latin square design. The intensity of pain was rated on a 0 to 10 cm visual analogue scale (VAS) score. Neither the investigator nor the volunteer was aware of the nature of the injectate. The pH of the injected solutions was checked to determine if differences in the intensity of pain on injection were due to differences in the pH of the solutions.
The VAS pain scores were 3.1 +/- 2.4 for needle only, 4.4 +/- 2.8 for bupivacaine, 2.5 +/- 2.0 for ropivacaine, 4.7 +/- 2.7 for bupivacaine/dexamethasone, and 3.7 +/- 2.2 for ropivacaine/dexamethasone. The pain on injection of ropivacaine was significantly less than the pain on injection of bupivacaine or bupivacaine/dexamethasone. The pH values of the solutions were as follows: (1) bupivacaine, 5.50; (2) ropivacaine, 5.57; (3) bupivacaine/dexamethasone, 6.64; and (4) ropivacaine/dexamethasone, 6.60.
The pain on intramuscular injection of bupivacaine is significantly more intense than with ropivacaine. The difference in the intensity of the pain on injection between bupivacaine and ropivacaine does not appear to be related to differences in pH. The results of our study have implications on the choice of the local anesthetic used in trigger point injections.
我们希望确定哪种长效局部麻醉药在注射治疗肌筋膜疼痛障碍时产生的疼痛最小。我们比较了布比卡因、罗哌卡因、布比卡因加地塞米松、罗哌卡因加地塞米松以及单纯进针时肌肉注射的疼痛情况。
30名志愿者每人接受5次注射：（1）仅进针；（2）0.5%布比卡因；（3）0.5%罗哌卡因；（4）0.5%布比卡因加0.13mg/mL地塞米松；（5）0.5%罗哌卡因加0.13mg/mL地塞米松。注射部位为志愿者的上斜方肌；两次注射间隔15分钟。注射顺序采用拉丁方设计随机安排。疼痛强度根据0至10厘米视觉模拟量表（VAS）评分。研究者和志愿者均不知道注射剂的性质。检查注射溶液的pH值，以确定注射时疼痛强度的差异是否由于溶液pH值的不同。
仅进针时VAS疼痛评分为3.1±2.4，布比卡因注射时为4.4±2.8，罗哌卡因注射时为2.5±2.0，布比卡因/地塞米松注射时为4.7±2.7，罗哌卡因/地塞米松注射时为3.7±2.2。罗哌卡因注射时的疼痛明显低于布比卡因或布比卡因/地塞米松注射时的疼痛。溶液的pH值如下：（1）布比卡因，5.50；（2）罗哌卡因，5.57；（3）布比卡因/地塞米松，6.64；（4）罗哌卡因/地塞米松，6.60。
布比卡因肌肉注射时的疼痛明显比罗哌卡因剧烈。布比卡因和罗哌卡因注射时疼痛强度的差异似乎与pH值的差异无关。我们的研究结果对触发点注射中局部麻醉药的选择具有启示意义。
