Isoflurane and mivacurium chloride neuromuscular blockade in patients with myasthenia gravis.

The relaxograph findings are presented in two patients. In the first, isoflurane alone is administered, and mivacurium with isoflurane is administered to the second patient with myasthenia gravis. A significantly lower dose of mivacurium is required. It was noticed that the T4:T1 ratio was 100% after mivacurium and reversal agent, but T1 did not return to normal. In the patient that only received isoflurane, T1 was 60% to 70% of the baseline, indicating the neuromuscular blocking effects of isoflurane. These cases illustrate that inhalation anesthetics are adequate for muscle relaxant effects, and if neuromuscular blockers are necessary, then a lower dose of nondepolarizer should be administered, and the patient carefully monitored. Mivacurium appears to be an ideal agent for neuromuscular blockade in myasthenia gravis as long as careful neuromuscular blockade is performed.