Assessment of Neuromuscular Blockade Depth Using Train-of-Four (TOF) Monitoring Following Rocuronium Extravasation

This report describes a case of accidental rocuronium extravasation in a patient with end-stage renal disease. We were unable to assess the depth of neuromuscular blockade due to fluctuating train-of-four (TOF) counts ranging from 0 to 4 between 37 and 90 minutes post-first rocuronium administration. However, the first twitch height in TOF stimulation (T1) was persistently low during this period and appeared to reflect a deep level of neuromuscular blockade. Thereafter, T1 increased steadily in response to rising TOF count and TOF ratio. In our case, T1 was low on average during TOF count fluctuation, at 2 ± 2% (mean ± standard deviation). Between 91 and 105 minutes post-first rocuronium administration, TOF counts of 4 were observed more frequently, and the mean T1 increased to 7 ± 4%. Beginning at 106 minutes post-first rocuronium administration, the TOF count remained constant at 4, and the mean T1 increased to 9 ± 3%. Beginning at 135 minutes, the TOF ratio appeared to be constant, and the mean T1 increased to 18 ± 5% until 162 minutes. At 185 minutes post-first rocuronium administration, we administered sugammadex 200 mg (3.17 mg/kg) after the patient's breathing had recovered spontaneously (end-tidal CO₂ was 42 mmHg, tidal volume exceeded 6 mL/kg, and respiratory rate was 12 breaths/min). The patient experienced no adverse events such as postoperative recurarization. In our case, although the TOF count was unstable, T1 appeared to reliably reflect changes in the depth of neuromuscular blockade.