title: The dose-effect relationship for morphine and vomiting after day-stay tonsillectomy in children.
abstract: A dose-response curve for intravenous morphine and vomiting was investigated in children having day-stay tonsillectomy. A retrospective chart review was performed for the 164 children fulfilling the inclusion criteria. Morphine (mean 0.09 mg/kg SD 0.05) was used in 108 children in the perioperative period and a further 56 children were given no opioid. Fifty-five of these 164 children vomited and 20 children required an overnight stay in hospital because of vomiting. The probability of vomiting or overnight stay in hospital was related to morphine dose (by logistic regression). The overall probability of vomiting after morphine 0.1 mg/kg was 50% and the probability of admission for vomiting with this dose was 10%. Pharmacodynamic parameter estimates for postoperative vomiting were P0 (the baseline probability of vomiting, with no opioid) 0.115, Pmax (the maximal probability of vomiting due to morphine) 0.997, ED50 (morphine dose that induces an effect equivalent to 50% of the logit Pmax) 0.18 mg/kg. Parameter estimates for overnight stay because of vomiting after morphine administration were P0 0.038, Pmax 0.999, ED50 0.369 mg/kg. Satisfactory postoperative analgesia in children has been reported with morphine 0.05 to 0.15 mg/kg. Doses above 0.1 mg/kg are associated with a greater than 50% incidence of vomiting. Our data suggests that lower doses of morphine are associated with a decreased incidence of emesis after tonsillectomy in children.
authors.affiliation: Department of Anaesthesia, Auckland Children's Hospital, Grafton, New Zealand.
authors.forename: B J
authors.initials: BJ
authors.lastname: Anderson
authors.forename: C J
authors.initials: CJ
authors.lastname: Ralph
authors.forename: A W
authors.initials: AW
authors.lastname: Stewart
authors.forename: C
authors.initials: C
authors.lastname: Barber
authors.forename: N H
authors.initials: NH
authors.lastname: Holford
mesh_terms: D000293:Adolescent; D000556:Ambulatory Surgical Procedures; D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000009:adverse effects* / Q000493:pharmacokinetics; D002648:Child; D002675:Child, Preschool; D004305:Dose-Response Relationship, Drug; D006801:Humans; D016015:Logistic Models; D009020:Morphine / Q000008:administration & dosage / Q000009:adverse effects* / Q000493:pharmacokinetics; D010149:Postoperative Pain / Q000188:drug therapy; D020250:Postoperative Nausea and Vomiting / Q000139:chemically induced*; D012189:Retrospective Studies; D014068:Tonsillectomy
chemical_list: D000701:Analgesics, Opioid; D009020:Morphine