Influence of disease progression on the neuromuscular blocking effect of mivacurium in children and adolescents with Duchenne muscular dystrophy.

Background: Studies with nondepolarizing neuromuscular blocking agents showed a delayed onset and prolonged recovery in patients with Duchenne muscular dystrophy. The objective of this study was to investigate if these alterations depend on disease progression.
Methods: The authors studied 11 children (6-9 yr) with moderate Duchenne muscular dystrophy, 11 adolescents (12-16 yr) with advanced Duchenne muscular dystrophy, and 2 age-matched control groups of 8 patients each (5-9 and 10-17 yr). Anesthesia was performed with propofol and remifentanil. Patients received a single intravenous dose of 0.2 mg/kg mivacurium. Neuromuscular transmission was monitored by acceleromyography. The time course of neuromuscular blockade was characterized by the onset time and the times to different levels of recovery.
Results: Onset and duration of neuromuscular blockade were significantly prolonged in adolescent Duchenne muscular dystrophy patients (onset time, 4.0 min; recovery index, 12.3 min; median), as compared with Duchenne muscular dystrophy children (onset time, 2.3 min; recovery index, 6.8 min), and also as compared with young controls (onset time, 2.0 min; recovery index, 4.4 min) and adolescent controls (onset time, 2.5 min; recovery index, 4.8 min). Within the Duchenne muscular dystrophy patients, onset time and recovery index increased significantly with age. In the control group, age had no effect.
Conclusions: The neuromuscular blocking effects of mivacurium showed a significant age dependency in Duchenne muscular dystrophy patients, which was most probably caused by the progression of the disease.