PLASMA LAUDANOSINE LEVELS IN PATIENTS GIVEN ATRACURIUM DURING LIVER-TRANSPLANTATION

Atracurium, a nondepolarizing muscle relaxant, does not depend on the liver for clearance, but its principal metabolite, laudanosine, is eli minated primarily by the liver and is potentially neurotoxic. We measu red atracurium and laudanosine levels in 15 adult patients during the three stages of liver transplantation to assess the effect of major im pairment of liver function. Atracurium was given in a bolus dose of 0. 5 mg/kg followed by continuous infusion at a rate adjusted to maintain 95-99% of total neuromuscular block, as judged by train of four respo nse to facial nerve stimulation. Atracurium levels remained constant a t 1.4-1.8 mug/mL during the 180-min preanhepatic and 75-min anhepatic stages but decreased to a mean of 1.0 mug/mL by the end of the 180-min postanhepatic stage. In contrast, laudanosine levels increased during each stage, being 0.40 +/- 0.18, 0.50 +/- 0.22, and 0.43 +/- 0.16 mug /mL after the preanhepatic, anhepatic, and postanhepatic stages, respe ctively. The highest individual value recorded was 1.02 mug/mL. We con clude that, despite increases in laudanosine levels during each stage of liver transplantation in patients receiving atracurium, those level s are only about one-tenth of the maximum values previously reported i n humans.