Intravenous lidocaine infusion in the treatment of experimental human skin burns - digital colour image analysis of erythema development.

Previous studies have shown that local anaesthetics possess a wide range of effects on the pathophysiology of burns, including inhibition of burn oedema and inhibition of progressive burn ischemia. The present randomised double-blind cross-over study in six volunteers investigated the effects of intravenous lidocaine infusion on partial thickness skin burns. A thermoprobe was used to induce a standardised thermal injury (1 cm(2)) on the flexor side of one forearm and was repeated on the opposite side 1 week later. Subjects received either an intravenous bolus dose of lidocaine (1 mg kg(-1)) immediately after the thermal trauma followed by continuous intravenous infusion of lidocaine (40 microg kg(-1) min(-1)) during 4 h or equal volumes of isotonic saline. Macrophotographs of the experimental skin area were taken preburn and 1, 2, 3, 4, and 12 h postburn and evaluated by computerised image colour analysis using normalised rgb (n-rgb) and Hue-Saturation-Intensity (HSI) colour systems as a quantitative measure of pathophysiological events. Maximum erythema occurred 2-3 h postburn. Differences between lidocaine- and placebo-treated burns were not significant during the first 4 h postburn. At 12 h postburn, the lidocaine-treated burn demonstrated a significantly faster restitution of residual erythema compared to control sites. The present study shows that intravenous lidocaine significantly inhibits the long-term inflammation-induced tissue responses to thermal trauma.