Neuromuscular effects of rapacuronium in pediatric patients during nitrous oxide-halothane anesthesia: comparison with mivacurium.
OBJECTIVE
To describe neuromuscular effects of rapacuronium in pediatric patients during N2O-halothane anesthesia and compare them with mivacurium in children.


METHODS
103 pediatric patients, seven days -12 yr, received rapacuronium or mivacurium during N2O-halothane anesthesia. Onset and recovery of block were measured using EMG (Datex). Block was compared between groups based on drug treatment and age. Children < two years received 1 or 2 mg x kg(-1) rapacuronium: 2-12 yr received either 2 mg x kg(-1) or 3 mg x kg(-1) rapacuronium, or 0.2 mg x kg(-1) mivacurium.


RESULTS
There were no differences in onset (1.7+/-1.8 min) or maximum block (T1 2.4+/-8%) among neonates, infants, and toddlers after either dose of rapacuronium. There was no difference between 1 and 2 mg x kg(-1) of rapacuronium block at 60 sec. Train-of-four ratio (T4/T1) >0.7 occurred later after 2 mg x kg(-1) than 1 mg x kg(-1) in these patients (P<0.05). There was no difference in T25 among neonates, infants and toddlers for 1 mg x kg(-1) or 2 mg x kg(-1) doses. Rapacuronium, 3 mg x kg(-1), produced maximum block 1.5 min earlier than did mivacurium, 0.2 mg x kg(-1) (P<0.001). There was no difference in block at 60 sec, maximum block or time to maximum block between 2 and 3 mg x kg(-1) rapacuronium for children > two years of age. Maximum block occurred 1.0+/-0.5 min after 2 or 3 mg x kg(-1) when T1 was 0.2+/-1.1% of baseline. T25 and T4/T1 >0.7 occurred 10 to 11 min later after this dose of rapacuronium than after mivacurium.


CONCLUSIONS
Rapacuronium produces block earlier than mivacurium. Recovery from rapacuronium block is dose related and slower than that following mivacurium during halothane anesthesia.
Brandom
B W
BW
Department of Anesthesiology, Children's Hospital of Pittsburgh, Pennsylvania 15213-2583, USA. bwb+@pitt.edu
Margolis
J O
JO
Bikhazi
G B
GB
Ross
A K
AK
Ginsberg
B
B
Dear
G
G
Kenaan
C A
CA
Eck
J B
JB
Woelfel
S K
SK
Lloyd
M E
ME
D000769:Anesthesia, Inhalation; D002648:Child; D002675:Child, Preschool; D004305:Dose-Response Relationship, Drug; D006221:Halothane / Q000008:administration & dosage; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007546:Isoquinolines / Q000494:pharmacology*; D000077590:Mivacurium; D003473:Neuromuscular Nondepolarizing Agents / Q000494:pharmacology*; D009609:Nitrous Oxide / Q000008:administration & dosage; D014673:Vecuronium Bromide / Q000031:analogs & derivatives* / Q000494:pharmacology
D007546:Isoquinolines; D003473:Neuromuscular Nondepolarizing Agents; D000077590:Mivacurium; D014673:Vecuronium Bromide; C082938:rapacuronium; D009609:Nitrous Oxide; D006221:Halothane