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

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

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.

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).

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.