Variability of cisatracurium in myasthenia gravis: case report

Case report. A myasthenic patient (Osserman II B), who received 0.1 mg.kg-1 cisatracurium during a propofol-fentanyl-O2:air anaesthesia, was monitored by Datex electromyography. The cisatracurium resulted in rapid onset of complete (100%) neuromuscular block in 3.6 min; a clinical duration (time from injection of cisatracurium to 25 % ratio of the first twitch of the train-of-four to the control twitch (T1/C ratio)) of 42 min; a recovery index (25% to 75 % T1/C ratio) of 37 min, and recovery TOF-ratios (ratio of the fourth to the first evoked response) of 0.75, 0.90, 0.95 and 1 in 65.5 min, 75.3 min, 84 min and 96.3 min respectively. Conclusion. The myasthenic patient is sensitive to cisatracurium, as evidenced by a more rapid onset and more marked neuromuscular block. This may be attributed to the decreased number of functional endplate acetylcholine receptors with a consequent decrease of the safety margin of neuromuscular transmission. Anestezjologia i Ratownictwo 2009; 3: 123-127