Influence of high dose tumescent local anaesthesia with prilocaine on systemic interleukin (IL)-6, IL-8 and tumour necrosis factor-α.

Background and objective Tumescent local anaesthesia (TLA) with high prilocaine doses leads to formation of methemoglobin (MHb) which is known to be a potent activator of pro-inflammatory endothelial cell response in vitro. As TLA is widely used for large dermatological resections, the aim of this study was to investigate the effects of high prilocaine doses on the systemic inflammatory response in vivo and its clinical relevance. Methods This prospective study examines the influence of MHb on serum interleukin (IL)-6, IL-8 and tumour necrosis tumour necrosis (TNF)-alpha levels up to 72 h after application of TLA with prilocaine in doses higher than 600 mg. Results A total of 30 patients received prilocaine in a median dose of 1500 mg (range: 880-4160 mg) for large resections. Peak prilocaine serum concentration was reached 4 h (0.72 +/- 0.07 mu g/mL), the maximum concentration of MHb (7.43 +/- 0.87%) and IL-6 (28.4 +/- 4.1 U/L) 12 h after TLA application. TNF-alpha and IL-8 release were not found significantly increased. Three patients developed MHb concentrations > 15%. Conclusions This clinical study shows for the first time that a high prilocaine serum concentration leads in vivo to elevated systemic levels of IL-6 but not of IL-8 and TNF-alpha because of initial high MHb levels. Because of possible and unpredictable high MHb concentrations, TLA should only be performed with prilocaine in doses of 2.5 mg/kg. In general, new solutions of TLA are necessary to achieve adequate anaesthesia for large dermatological resections to decrease the risk of methemoglobinaemia.