Transdermal diclofenac patch vs eutectic mixture of local anesthetics for venous cannulation pain.

PURPOSE: To compare the efficacy and side effects of transdermal diclofenac patch with eutectic mixture of local anesthetic (EMLA) cream in attenuating venous cannulation pain.

METHODS: Adult ASA I or II patients undergoing elective surgery were randomly divided into three groups of 150 each. Group 1 (Control) patients received a placebo patch; Group 2 (EMLA) patients received EMLA cream; Group 3 (Diclofenac) patients received a transdermal diclofenac patch. The patches were applied at the proposed venous cannulation site 60 min prior to cannulation and pain resulting from an 18G cannula was assessed on an ten-point visual analogue scale (VAS). The cannulation site was observed for blanching, erythema, induration and edema for up to 24 hr.

RESULTS: The incidence of venous cannulation pain was 100% in the control group, as compared to 37% and 48% of patients who experienced pain in the EMLA (P = 0.001) and diclofenac (P = 0.001) groups, respectively. The severity of venous cannulation pain [median (VAS) with interquartile ranges] was also higher in the control group: 6 (3) as compared to VAS sores of 0 (1) and 0 (2) in the EMLA (P = 0.001) and diclofenac (P = 0.001) groups. Blanching occurred with greater frequency in the EMLA group compared with the diclofenac (P = 0.001 at six hours) and placebo groups (P = 0.001 at six hours). Erythema, induration and edema were reduced in the diclofenac group compared with the EMLA (P = 0.001 for all comparisons) and placebo groups (P = 0.04 for edema at six hours and P = 0.001 for other comparisons).

CONCLUSION: Transdermal diclofenac patch and EMLA are equally effective in reducing venous cannulation pain, but signs of erythema, induration and edema are less frequently observed with the transdermal diclofenac patch.