Lidocaine and bupivacaine exert differential effects on whole blood coagulation

Study Objectives: To compare bupivacaine to lidocaine's effects on blood clotting at two concentrations, and to characterize and determine relative effects of two equianalgesic bupivacaine and lidocaine concentrations. Design: Prospective, dual-controlled, whole blood equal volume admixture thrombelastographic (TEG(TM)) study. Setting: University of Pennsylvania Medical Center operating rooms. Patients: 20 ASA physical status I and II patients' blood comprised control groups and anesthetic groups. Interventions: Analysis of whole blood clotting used six TEG(TM) channels for untreated and saline controls and four final concentrations (1.0% lidocaine, 0.5% lidocaine, 0.25% bupivacaine, and 0.125% bupivacaine) of local anesthetics. Saline control and the local anesthetic-treated specimens underwent 8.3% hemodilution. Measurements and Main Results: Blood was studied. Saline control or four anesthetic solutions (30 μl) were added in random order two 5 TEG(TM) cuvettes. Whole blood (330 μl) was mixed ex vivo at 37°C. A sixth channel with untreated whole blood (360 μl) acted as an undiluted control. Data for four TEG(TM) parameters [reaction time (r), angle (α), maximum amplitude (MA), and percent decrease in TEG amplitude from MA 30 minutes after MA acquisition (Lysis 30)] for undiluted control and saline volumetric controls were compared to each other using Student's t-test for paired observations. Lidocaine and bupivacaine groups' TEG(TM)s were compared to the paired saline control analysis of variance for repeated measures. A p- value less than 0.05 was considered significant. There was no difference between whole blood and saline control TEG(TM)s. All local anesthetics produced significant hypocoagulable changes from control. Angle α and MA were significantly decreased in all local anesthetic groups. The r time was prolonged only in the high lidocaine-treated blood. Lysis was a feature of the low lidocaine and bupivacaine solutions. Equianalgesic lidocaine produced more profound hypocoagulable effects than did bupivacaine. Conclusions: Lidocaine and bupivacaine both significantly impaired TEG(TM) coagulation in a concentration-dependent manner. Lidocaine was significantly more hypocoagulable than bupivacaine at two similarly analgesic concentrations.