BACKGROUND: Myasthenia gravis is an autoimmune neuromuscular disorder that shows increased sensitivity to nondeporalizing muscle relaxants. Atracurium is eliminated by Hofmann elimination and ester hydrolysis. We studied the onset and duration of atracurium is patients with mysthenia gravis.
METHODS: Ten patients undergoing thymectomy for myastenia gravis and ten patients of ASA class I-II without liver, kidney and neuromuscular disease for orthopedic surgical procedures were assigned to two groups of control and myasthenia gravis. Anesthesia was induced with thiopental and maintained with the inhalation of N2O-O2(1:1) and isoflurane(0.5-1.5vol%). Atracurium(0.5mg/kg) was given as a muscle relaxnats and then intubation was performed after twitch response was depressed more than 80%. Neuromuscular relaxarion was assessed by TOF(T1) at the adductor pollicis with supramximal stimulation of ulnar nerve at 2 Hz every 12 seconds. The onset and duration of 5, 25, 50, 75%, 95% recovery time of T1 and recovery index were recorded.
RESULTS: Onset of block shortened and recovery time of 5, 25, 50, 75, 95% and recovery index were prolonged in patients with myasthenia gravis.
CONCLUSIONS: Atracurium is the patients with myasthenia gravis induced rapid onset and prolonged recovery time of 5, 25, 50, 75, 95% and recovery index.
REFENENCE: 1. Can J Anaesth 1992; 39(5):476-486. 2. Anesth Analg 1984; 63:1127-1130.
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