Inconsistency with train-of-four monitoring in a critically ill paralyzed patient.

Problems occurred with train-of-four (TOF) monitoring during prolonged therapy with nondepolarizing neuromuscular blocking agents (NNMBAs). A previously healthy 25-year-old male with metastatic testicular teratocarcinoma was paralyzed with an atracurium infusion to facilitate mechanical ventilation. Dosage titration was initially based on clinical assessment; however, on day 4 of atracurium, TOF monitoring was initiated. During days 4 to 10 of atracurium therapy, TOF monitoring correlated well with clinical assessment of the depth of paralysis. On day 13, atracurium was discontinued and a pancuronium infusion was initiated. During the 9 days of pancuronium therapy, TOF monitoring suggested overparalysis on several occasions (no thumb twitch at 80 mamp of ulnar nerve stimulation) despite clinical evidence of spontaneous movement or respirations. The patient was edematous and had extremely dry skin during some of these instances of inappropriate TOF response. Although these problems were rectified, TOF response continued to be erroneous. Thus we had to rely primarily on clinical assessment to monitor the duration of NNMBA therapy. This case demonstrates that TOF data and clinical assessment of neuromuscular blockade may not always correlate.