Postoperative morphine concentration in infants with or without biliary atresia and its association with hepatic blood flow.

We measured pre-operative hepatic blood flow and postoperative morphine concentration in infants with or without biliary atresia. Thirty-four infants (0-3 months) with biliary atresia undergoing portoenterostomy (Kasai operation) were included and hepatic blood flow was assessed by magnetic resonance imaging before surgery in 12 of them. Sixteen subjects (0-3 months) without liver disease undergoing abdominal or pelvic surgery acted as controls and six of them had hepatic blood flow assessed. Intravenous morphine (8 µg.kg(-1).h(-1)) was administered to all patients postoperatively. The median (IQR [range]) relative hepatic blood flow was 3.51 (2.72-3.88 [1.68-4.43]) with and 3.15 (2.66-4.42 [2.30-5.01]) without biliary atresia (p = 0.851). The median (IQR [range]) morphine concentration after 24 h infusion was 5.9 (4.5-16.4 [2.9-42.2]) ng.ml(-1) and 6.4 (3.2-12.0 [1.9-48.6]) ng.ml(-1) , respectively (p = 0.460). An inverse regression relation was found between the morphine concentration and the hepatic perfusion index (R(2) = 0.519, p = 0.001). Compensatory increases in hepatic arterial blood flow maintain the total hepatic blood flow in infants with biliary atresia.

Postoperative respiratory and analgesic effects of dexmedetomidine or morphine for adenotonsillectomy in children with obstructive sleep apnoea.

The postoperative respiratory and analgesic effects of dexmedetomidine and morphine have not been compared in children with sleep apnoea having adenotonsillectomy. In a randomised double-blind study we recruited 60 children, aged 2-13 years, who received either intravenous dexmedetomidine 1 µg.kg(-1) or morphine 100 µg.kg(-1) on anaesthetic induction. End-tidal carbon dioxide, Children's Hospital of Eastern Ontario Pain Scale score and supplementary morphine administration were recorded every 15 min for 60 min postoperatively. Over 60 min, mean (SD) end-tidal carbon dioxide was consistently lower with dexmedetomidine compared with morphine (5.4 (0.7) kPa vs 6.0 (0.6) kPa, respectively; p = 0.001). Mean (SD) pain scores were higher with dexmedetomidine (8.1 (2.0) immediately postoperatively and 6.7 (1.0) at 60 min vs 7.6 (1.8) and 6.3 (0.7), respectively, with morphine (p = 0.023)). More patients required supplementary morphine with dexmedetomidine (13/30 (43%) vs 21/30 (70%); p = 0.037). Postoperatively, dexmedetomidine produced less respiratory depression than morphine, but less effective analgesia.