Pain during venous cannulation: Double-blind, randomized clinical trial of analgesic effect between topical amethocaine and eutectic mixture of local anesthetic

BACKGROUND: Venous cannulation is often a painful procedure for the patient. Eutectic mixture of local anesthetic (EMLA) is the commonest topical analgesic used but suffers from disadvantages such as slow onset and skin blanching, which may interfere with venous cannulation. Amethocaine is a newer topical analgesic which seems to be devoid of such problems.

MATERIALS AND METHODS: This prospective randomized double-blind study compared the analgesic efficacy of EMLA with amethocaine during venous cannulation in adults. Eighty ASA I-II patients, aged 18-65 years, were recruited. The test drug was applied on the designated site of venous cannulation and covered with an occlusive dressing for at least 60 min prior to the procedure. Data collected included visual analogue score (VAS) during first attempt at venous cannulation, the ease and success rate at cannulation, and cutaneous changes at the application site.

RESULTS: Mean and median VAS for the EMLA group were 27.9 ± 9.8 and 30 mm, respectively; while for the Amethocaine group were 19.1 ± 14.1 and 20 mm, respectively. Differences in VAS did not reach statistical significance. No statistically significant differences were observed in the ease and success rate at cannulation. Cutaneous changes in the form of local induration and erythema (three patients in the Amethocaine group) and blanching (eight patients in the EMLA group) were mild, localized, and required no further treatment. No patient developed severe allergic reactions.

CONCLUSION: Topical EMLA and amethocaine were comparable in terms of analgesic efficacy and ease of venous cannulation in adult patients.