Onset and duration of mivacurium-induced neuromuscular block in patients with Duchenne muscular dystrophy.
BACKGROUND
To determine the response to mivacurium, we prospectively studied onset time and complete spontaneous recovery from mivacurium-induced neuromuscular block in patients with Duchenne muscular dystrophy (DMD).


METHODS
Twelve boys with DMD, age 5-14 yr, seven of them wheelchair-bound, ASA II-III, and 12 age- and sex-matched controls (ASA I) were enrolled in the study. Anaesthesia was induced with fentanyl 2-3 microg kg(-1) and propofol 3-4 mg kg(-1) titrated to effect, and maintained by continuous i.v. infusion of propofol 8-12 mg kg(-1) and remifentanil as required. The lungs were ventilated with oxygen in air. Neuromuscular transmission was assessed by acceleromyography using train-of-four (TOF) stimulation every 15 s. After baseline readings, a single dose of mivacurium 0.2 mg kg(-1) was given. The following variables were recorded: (i) lag time; (ii) onset time; (iii) peak effect; (iv) recovery of first twitch from the TOF response to 10, 25 and 90% (T(10), T(25), T(90)) relative to baseline; (v) recovery index (time between 25 and 75% recovery of first twitch); and (vi) recovery time (time between 25% recovery of first twitch and recovery of TOF ratio to 90%). For comparison between the groups the Mann-Whitney U-test was applied.


RESULTS
There were no differences between the groups in lag time, onset time and peak effect. However, all recorded recovery indices were significantly (P<0.05) prolonged in the DMD group. The median (range) for time points T(10), T(25) and T(90) in the DMD and control group was 12.0 (8-16) vs 8.4 (5-15) min, 14.1 (9-20) vs 10.5 (7-17) min and 26.9 (15-40) vs 15.9 (12-23) min, respectively. The recovery index and recovery time were similarly prolonged in the DMD group.


CONCLUSIONS
These results support the assumption that mivacurium-induced neuromuscular block is prolonged in patients with DMD.
Schmidt
J
J
Department of Anaesthesiology, Friedrich-Alexander University, Erlangen-Nuremberg, Krankenhausstrasse 12, D-91054 Erlangen, Germany.
Muenster
T
T
Wick
S
S
Forst
J
J
Schmitt
H J
HJ
D000293:Adolescent; D000762:Anesthesia Recovery Period; D000768:Anesthesia, General / Q000379:methods; D000886:Anthropometry; D002648:Child; D002675:Child, Preschool; D002802:Cholinesterases / Q000097:blood; D006801:Humans; D007546:Isoquinolines / Q000494:pharmacology*; D008297:Male; D000077590:Mivacurium; D020388:Muscular Dystrophy, Duchenne / Q000503:physiopathology*; D019148:Neuromuscular Blockade; D009469:Neuromuscular Junction / Q000187:drug effects* / Q000503:physiopathology; D003473:Neuromuscular Nondepolarizing Agents / Q000494:pharmacology*; D019637:Orthopedic Procedures; D011446:Prospective Studies
D007546:Isoquinolines; D003473:Neuromuscular Nondepolarizing Agents; D000077590:Mivacurium; D002802:Cholinesterases