The number of injections does not influence absorption of bupivacaine after cervical plexus block for carotid endarterectomy

Abstract

Study ObjectiveTo investigate the efficacy and kinetics of bupivacaine when used for deep cervical plexus block (CPB), using either a single-injection or multiple-injections technique. DesignProspective, randomized, double-blind study. SettingOperating room of a university hospital. PatientsTwenty-four adult patients (16 men, 8 women) scheduled for carotid endarterectomy. InterventionsPatients were randomly assigned to receive CPB either by a single injection or after 3 injections. Patients in the multiple-injections group received a total dose of 15 mL of 0.5% bupivacaine (5 mL each deposited at C2, C3, and C4 over 2 minutes). Patients in the single-injection group received a single 15-mL injection of 0.5% bupivacaine. After the deep CPB, a superficial CPB was performed with 20 mL of 0.5% bupivacaine in all patients. MeasurementsAn anesthesiologist and a surgeon graded the success of the block. Arterial plasma concentrations of bupivacaine were measured using liquid chromatography–mass spectroscopy. Main ResultsNo significant differences were seen between the 2 groups with respect to the mean peak concentration of bupivacaine (single injection 2314 ± 1385 ng/mL vs multiple injections 2255 ± 1105 ng/mL) or time to reach the maximal concentration (time to maximum concentration [single injection 12.1 ± 7.2 minutes vs multiple injections 12.5 ± 3.9 minutes]). Furthermore, there were no significant differences in mean block scores between the single-injection and the multiple-injections groups, evaluated either by the anesthesiologists or the surgeon. ConclusionsThe results of this study showed that the absorption of bupivacaine is independent of the number of injections after CPB, and that anesthesia for carotid endarterectomy may be accomplished successfully using either technique.