• R G Rohling, K M Rentsch, B Beck-Schimmer, and T Fuchs-Buder.
• Institute of Anesthesiology, University Hospital Zurich, Zurich, Switzerland. ro.rohling@klinikbethanien.ch
• J Clin Anesth. 2003 Mar 1;15(2):85-90.

Study ObjectivesIn the context of acute normovolemic hemodilution (ANH) recurarization, defined as significant decrease of train-of-four ratio (TOFR) during retransfusion of autologous blood withdrawn after induction of anesthesia, has been described for vecuronium and atracurium. The present study for the first time examined this risk for rocuronium and mivacurium.DesignProspective, randomized, unblinded clinical study.SettingUniversity Hospital in Zurich/Switzerland.Patients20 ASA physical status I and II patients undergoing general anesthesia for major maxillofacial surgery.InterventionsAnesthesia was induced and maintained with propofol and remifentanil, and rocuronium (0.9 mg kg(-1)) or mivacurium (0.25 mg kg(-1)) was given to facilitate intubation. Thereafter, ANH was started with the removal of 500 mL autologous blood and the subsequent replacement by the same amount of 6% hydroxyethyl starch. The withdrawn blood was stored at 4 degrees C until retransfusion at the end of surgery.MeasurementsTo estimate the risk of recurarization during retransfusion, the degree of recurarization during retransfusion of the autologous blood was assessed mechanomyographically. Plasma levels of rocuronium and mivacurium in the patients' plasma and the autologous blood were determined after its removal and before retransfusion.Main ResultsThe TOFR before retransfusion was 0.97 (range: 0.96 to 0.98) for rocuronium (n = 10) and 0.98 (range: 0.96 to 1.0) for mivacurium (n = 8); n.s. During retransfusion, a slight, but statistically significant reduction of TOFR occurred in one patient in each group. In the mivacurium group, this recurarization occurred 10 minutes after the start of retransfusion; in the rocuronium group, it occurred 20 minutes after retransfusion. The plasma levels of rocuronium and mivacurium in the autologous blood did not change during storage. The plasma concentration of mivacurium in the autologous blood after its removal was 420 +/- 142 microg/L; before retransfusion, it was 384 +/- 147 microg/L. The respective concentrations for rocuronium were 2930 +/- 516 microg/L and 2660 +/- 464 microg/L.ConclusionsRecurarization during retransfusion may occur with both neuromuscular blocking drugs, mivacurium and rocuronium, when these drugs were injected before the removal of the autologous blood.

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