The response of patients with Duchenne's muscular dystrophy to neuromuscular blockade with vecuronium

Background: The authors hypothesized that patients with Duchenne's muscular dystrophy (DMD) are more sensitive to nondepolarizing muscle relaxants. Methods: Eight children with DMD and eight healthy children having orthopedic procedures mere studied. Anesthesia consisted of thiopental, 60% nitrous oxide in 40% oxygen, and intravenous fentanyl and midazolam. Using electromyography, the ulnar nerve was stimulated and the electromyographic train-of-four ratio (TOFr) of the first dorsal interosseous muscle was recorded every 60 s. After baseline TOFr recording, all patients received 50 mu g/kg vecuronium and the TOFr at 3 min was compared. Vecuronium (10 mu g/kg) was then administered every minute until TOFr mas less than or equal to 0.1. The TOFr was followed until TOFr was greater than or equal to 0.01. Then 10 mu g/kg of vecuronium mere administered to maintain TOFr less than or equal to 0.1. At the conclusion of the procedure, TOFr was allowed to recover to 0.25, and then neostigmine and glycopyrrolate were administered Data are presented as medians and ranges. Results: The initial dose of vecuronium resulted in greater TOFr depression in patients with DMD than in controls (0.14 vs. 0.86). Less vecuronium mas needed to produce TOPr less than or equal to 0.1 in the patients with DMD than in the control patients (55 mu g/kg us. 95 mu g/kg). Recovery time for the TOFr to greater than or equal to 0.1 after the initial dose was longer in the patients with DMD than in the controls (28 vs. 20 min; P = 0.03), and the maintenance dose of vecuronium mas less in patients with DMD (0.6 vs. 1.3 mu g.kg(-1).min(-1); P < 0.01). The time for TOFr recovery from 0.1 to 0.25 mas 36 min in the patients with DMD and 6 min in the controls (P < 0.01). After neostigmine, the TOFr was 1.0 in the controls and 0.91 (P = 0.03) in the patients with DMD. Conclusion: There is increased sensitivity to vecuronium from neuromuscular blockade in patients with DMD.