Hung O R, Comeau L, Riley M R, Tan S, Whynot S, Mezei M
Department of Anaesthesia, Dalhousie University, Halifax, Nova Scotia, Canada.
Can J Anaesth. 1997 Jul;44(7):707-11. doi: 10.1007/BF03013382.
The eutectic mixture of local anaesthetics (EMLA) provides effective topical anaesthesia after a minimum of 60 to 90 min application. Since liposome-encapsulated tetracaine (LET) can provide rapid dermal penetration, the goal of this study was to compare the local anaesthetic effects of EMLA and LET in human volunteers after 60 min application.
After obtaining institutional approval and informed consent, healthy volunteers were recruited in a double blind, crossover, randomized trial. The study creams (0.5 ml EMLA and 0.5 ml LET 5%) were applied randomly to opposite arms for 60 min. The discomfort of i.v. catheterization was assessed using a visual analogue pain score (VAS). Cutaneous side effects of the creams were recorded.
Sixty-one subjects were studied. Twenty-one were excluded because of technical difficulties. Forty subjects completed the study and were included in the data analysis. The mean ( +/- SD) VAS was lower for LET than for EMLA (10.9 +/- 9.0 mm vs 22.7 +/- 17.1 mm, P < 0.001). Erythema secondary to vasodilatation occurred more frequent in the LET group than in the EMLA group (33 vs 3, P < 0.001). One subject with a history of atopy developed a rash at the LET application site.
Liposome-encapsulated tetracaine can provide a more effective topical anaesthesia than EMLA for intravenous catheterization after 60 min application. Clinical evaluations are necessary to determine the efficacy and safety of LET in providing topical anaesthesia for various invasive percutaneous procedures in other patient populations.
局部麻醉药的共晶混合物（EMLA）在应用至少60至90分钟后可提供有效的局部麻醉。由于脂质体包裹的丁卡因（LET）可实现快速的皮肤渗透，本研究的目的是比较应用60分钟后EMLA和LET在人类志愿者中的局部麻醉效果。
在获得机构批准并取得知情同意后，招募健康志愿者进行双盲、交叉、随机试验。将研究用乳膏（0.5 ml EMLA和0.5 ml 5% LET）随机涂抹于双侧手臂，持续60分钟。使用视觉模拟疼痛评分（VAS）评估静脉置管的不适程度。记录乳膏的皮肤副作用。
共研究了61名受试者。21名因技术困难被排除。40名受试者完成研究并纳入数据分析。LET组的平均（±标准差）VAS低于EMLA组（10.9±9.0 mm对22.7±17.1 mm，P<0.001）。LET组因血管扩张继发的红斑比EMLA组更常见（33例对3例，P<0.001）。一名有特应性病史的受试者在LET涂抹部位出现皮疹。
应用60分钟后，脂质体包裹的丁卡因在静脉置管方面比EMLA能提供更有效的局部麻醉。有必要进行临床评估以确定LET在为其他患者群体的各种侵入性经皮操作提供局部麻醉时的疗效和安全性。
