THE RESPONSE OF PATIENTS WITH DUCHENNES MUSCULAR-DYSTROPHY TO NEUROMUSCULAR BLOCKADE WITH VECURONIUM

Background: The authors hypothesized that patients with Duchenne's mus cular dystrophy (DMD) are more sensitive to nondepolarizing muscle rel axants. Methods: Eight children with DMD and eight healthy children ha ving orthopedic procedures mere studied. Anesthesia consisted of thiop ental, 60% nitrous oxide in 40% oxygen, and intravenous fentanyl and m idazolam. Using electromyography, the ulnar nerve was stimulated and t he electromyographic train-of-four ratio (TOFr) of the first dorsal in terosseous muscle was recorded every 60 s. After baseline TOFr recordi ng, 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 minu te until TOFr mas less than or equal to 0.1. The TOFr was followed unt il TOFr was greater than or equal to 0.01. Then 10 mu g/kg of vecuroni um mere administered to maintain TOFr less than or equal to 0.1. At th e conclusion of the procedure, TOFr was allowed to recover to 0.25, an d then neostigmine and glycopyrrolate were administered Data are prese nted as medians and ranges. Results: The initial dose of vecuronium re sulted in greater TOFr depression in patients with DMD than in control s (0.14 vs. 0.86). Less vecuronium mas needed to produce TOPr less tha n or equal to 0.1 in the patients with DMD than in the control patient s (55 mu g/kg us. 95 mu g/kg). Recovery time for the TOFr to greater t han 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 maint enance dose of vecuronium mas less in patients with DMD (0.6 vs. 1.3 m u 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 se nsitivity to vecuronium from neuromuscular blockade in patients with D MD.