Rocuronium plasma concentrations during three phases of liver transplantation: relationship with early postoperative graft liver function.

BACKGROUND: Previous studies have suggested that neuromuscular blocking agents might be used to assess liver function during liver transplantation. This study examines changes in rocuronium plasma concentration during liver transplantation, to assess graft function.
METHODS: A constant-rate infusion of rocuronium was administered to 17 adult patients undergoing liver transplantation. Blood samples were taken at 30-min intervals throughout the procedure, which was divided into three phases: paleo-, an-, and neohepatic. Assay of plasma concentrations of rocuronium was by a gas chromatographic-mass spectrometry technique. Postoperative liver function was followed for up to five days by measuring plasma aminotransferases.
RESULTS: In 14 of the 15 patients who survived the transplantation procedure, there was a 7-50% decrease in rocuronium concentration during the neohepatic phase compared with the anhepatic phase. In contrast, rocuronium concentrations increased in the two patients who died after surgery, one as a result of primary non-function and one from massive bleeding. In one patient who survived there was no change in rocuronium concentration. The increase in plasma rocuronium concentration during the neohepatic phase in the two patients who died was consistent with high levels of plasma aminotransferases.
CONCLUSIONS: Comparison of changes in plasma rocuronium concentration during the neohepatic phase with early postoperative liver function tests suggests the potential use of rocuronium as a pharmacokinetic probe for predicting liver function during liver transplantation. Further study of rocuronium's potential as an intraoperative pharmacodynamic probe of liver function by measuring neuromuscular paralysis is suggested.