TOPICAL LOCAL-ANESTHETICS (EMLA(R)) INHIBIT BURN-INDUCED PLASMA EXTRAVASATION AS MEASURED BY DIGITAL IMAGE COLOR ANALYSIS

Amide local anaesthetics have previously been shown to reduce oedema a nd improve dermal perfusion following experimental burns. Previous stu dies have used invasive techniques for burn oedema quantification whic h do not allow continuous monitoring in the same animal. The present s tudy used digital image colour analysis to investigate the effect of t opical local anaesthetics on burn-induced extravasation of Evans blue albumin. A standardised full-thickness burn injury (1 x 1 cm) was indu ced in the abdominal skin of anaesthetised rats. The burn area was sub sequently covered with 0.5 g of lidocaine-prilocaine cream 5% (25 mg o f each in Ig; EMLA(R), ASTRA, Sweden) or placebo cream during the firs t hour post-burn. One hour after the burn trauma, animals received Eva ns blue dye intravenously. Skin colour appearances were recorded by ma crophotography before the burn and 5, 60, 65, 90, 120, 150, and 180 mi n post-burn. Colour slides were digitised and colour changes were anal ysed using the normalised red-green-blue (n-rgb) colour system. Result s showed a significant inhibition of Evans blue extravasation between 60 and 180 min post-burn in EMLA(R)-treated animals versus controls. T opical local anaesthetics are potent inhibitors of burn-induced plasma albumin extravasation, probably by direct action on vascular permeabi lity and by inhibition of various steps of the pathophysiological resp onse after burn injury. (C) 1998 Elsevier Science Ltd for ISBI. All ri ghts reserved.