Age-related postoperative morphine requirements in children following major surgery--an assessment using patient-controlled analgesia (PCA)

To investigate if small children require less morphine for postoperative analgesia than do older children and adolescents we analysed the morphine consumption pattern of 28 consecutive children on intravenous patient-controlled analgesia (PCA) following major surgery. The median age-specific morphine requirements between 2 comparable groups of children aged 4-8 years and 9-15 years were compared. We used the Pharmacia-Deltec pump in all children and the same settings: a bolus dose of 25 microgram/kg, an 8 minutes lockout interval and no background infusion. In addition, all children received paracetamol as a supplemently to the morphine. In this study children aged 4-8 years had significantly higher total postoperative morphine requirements compared to children aged 9-15 years, i.e. 11.6 microgram/kg/hour and 7.5 microgram/kg/hour respectively (p = 0.037). Hence, we conclude that children of this age group may have a higher total postoperative morphine requirement following major surgery than older children and adolescents.