Comparison of topical anaesthesia methods for venous cannulation in adults.

A prospective, randomized clinical trial was performed in order to assess the efficacy and side-effects of commonly used topical anaesthesia methods in adults receiving peripheral venous cannulation. The study was double-blinded to the degree that the methodologies allowed. One hundred and fifty healthy adults undergoing elective surgery were allocated at random to five groups: EMLA cream, ethyl chloride spray, intracutaneous infiltration with 2% lidocaine, placebo cream and no treatment. Venipuncture was performed with a 18G cannula on the dorsal side of the hand. Puncture pain and pain caused by the topical treatment itself were measured using a visual analogue scale (VAS, range: 0-100 mm). Haemodynamic response, difficulties in performing the puncture and side-effects were recorded. All analgesic techniques were well tolerated. Haemodynamic response and degree of puncture difficulty showed no differences among the groups. Puncture pain (median mrnVAS) following infiltration (1.0) and EMLA (10.0) was significantly lower than no treatment (30.0) or placebo (30.0). The benefit of local infiltration was altered by injection pain (11.5). Spray did not significantly lower puncture pain (26.5) and, in addition, was associated with discomfort (10.5). In adults, EMLA cream significantly reduces puncture pain and represents an acceptable alternate method for topical anaesthesia in venous cannulation. Local lidocaine infiltration is impaired by applicational pain, whereas spraying the puncture site with ethyl chloride has no analgesic benefit.