Lidocaine inhibits blood coagulation: implications for epidural blood patch.

Lidocaine in the epidural space, through inhibitory effects upon coagulation, may contribute to inefficacy of epidural autologous blood patch (EBP). This study was undertaken to evaluate the effect of achievable epidural concentrations of lidocaine on blood coagulation as a step in testing this hypothesis. Ex vivo blood coagulation using whole blood (n = 20) was studied with computerized thrombelastography (TEG). Each blood specimen was exposed to serial dilutions of lidocaine hydrochloride or saline to form end-concentrations of 0.0 mM, 2.3 mM, 4.6 mM, 9.2 mM, 18.5 mM, and 36.9 mM lidocaine. Statistical analysis using analysis of variance for repeated measures revealed that the three highest lidocaine concentrations tested caused hypocoagulable and/or fibrinolytic changes as compared with controls. Achievable epidural admixtures of lidocaine and whole blood will impair coagulation. Therefore, residual lidocaine in the epidural space may contribute to failures of immediate or early EBP.