Does prior administration of enoxaparin influence the effects of levobupivacaine on blood clotting? Assessment using the Thrombelastograph®

Abstract

The low molecular weight heparin, enoxaparin (by inhibition of factors Xa and IIa) and amide local anaesthetics (by altering platelet function) exert anti-clotting effects. Although these agents are often used in combination during the perioperative period, their potential interactive effect on clotting has not been defined. Blood from 10 ASA I-II patients who received enoxaparin 0.5 mg kg-1 s.c. was studied using a Thrombelastograph (TEG®) either alone or in combination with levobupivacaine (2.5 mg ml-1 or 2.5 μg ml-1) or saline (50% dilution). In blood from patients who had received enoxaparin 0.5 mg kg-1 s.c. 12 h previously, levobupivacaine 2.5 mg ml-1 (but not 2.5 μg ml-1) produced significant changes in TEG clotting parameters (mean (SD) 15.7 (4.8) mm, 29.6 (25.6) mm, 34.4 (14.6) mm, 34.3 (12.2)° compared with control values of 6.1 (1.3) mm, 2.5 (0.5) mm, 63.5 (6.4) mm and 74.1 (2.9)° for r, K, MA, and α angle respectively).