The effect of epidural bupivacaine on vecuronium-induced neuromuscular blockade in children.
The effect of epidural bupivacaine on potency and duration of action of vecuronium-induced neuromuscular blockade (NMB) was evaluated in 30 general surgical paediatric patients (ASA I-II) of three to ten years of age. Premedication was midazolam 0.5 mg kg-1 orally (max 15 mg). In addition to general anaesthesia, 15 of the children received a lumbar epidural block with 0.5% bupivacaine 2.5 mg kg-1. Anaesthesia was induced and maintained with N2O:O2 (2:1), propofol and alfentanil. NMB was monitored by adductor pollicis EMG with the train-of-four stimulus every 20 sec. Thirty minutes following the epidural bupivacaine injection (mean plasma concentration 0.86 micrograms ml-1) or induction of anaesthesia a cumulative dose-response curve of vecuronium was established to achieve a 95% depression of the twitch response. Thereafter, NMB was allowed to recover spontaneously. ED doses of vecuronium were 19-22% greater in the control group than in the epidural group. ED50 doses were 33.8 (s.e. mean 1.3) micrograms kg-1 and 28.4 (2.2) micrograms kg-1, respectively (P < 0.05). There were no differences in recovery times from NMB between control and epidural group, the recovery index (time of twitch height to recover from 25 to 75%) being 6.4 (0.4) min and 7.0 (0.9) min, respectively. However, a negative correlation was found between bupivacaine plasma concentration and an ED50 dose of vecuronium (P = 0.01). Our results indicate that vecuronium is slightly more potent in children with bupivacaine epidural block than in children without it.
Taivainen
T
T
Department of Anaesthesiology, Children's Hospital, University of Helsinki, Finland.
Meretoja
O A
OA
Rosenberg
P H
PH
D015760:Alfentanil; D000767:Anesthesia, Epidural; D000768:Anesthesia, General; D002045:Bupivacaine / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D002648:Child; D002675:Child, Preschool; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004357:Drug Synergism; D004558:Electric Stimulation; D004576:Electromyography / Q000187:drug effects; D006801:Humans; D009469:Neuromuscular Junction / Q000187:drug effects*; D009609:Nitrous Oxide; D015742:Propofol; D009435:Synaptic Transmission / Q000187:drug effects; D014459:Ulnar Nerve / Q000187:drug effects / Q000502:physiology; D014673:Vecuronium Bromide / Q000008:administration & dosage / Q000494:pharmacology*
D015760:Alfentanil; D014673:Vecuronium Bromide; D009609:Nitrous Oxide; D002045:Bupivacaine; D015742:Propofol