The ketamine pharmacokinetics in children with minor burns are similar to those without burns. The peak ratio of norketamine/ketamine at 1 h is 2.8 after oral administration allowing an analgesic contribution from the metabolite at this time. There is low relative bioavailability (<0.5) and slow variable absorption. Dose simulation in a child (3.5 years, 15 kg) suggests a dose regimen of oral ketamine 10 mg·kg(-1) followed by intravenous ketamine 1 mg·kg(-1) i.v. with the advent of short-duration surgical dressing change at 45 min.

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SummaryWe examined the haemodynamic effects of colloid preload, and phenylephrine and ephedrine administered for spinal hypotension, during caesarean section in 42 women with severe early onset pre-eclampsia. Twenty patients with predelivery spinal hypotension were randomly allocated to receive an initial dose of either 50 lg phenylephrine or 7.5 mg ephedrine; the primary outcome was percentage change in cardiac index. After a 300-ml colloid preload, mean (SD) cardiac index increased from 4.9 (1.1) to 5.6 (1.2) l.min À1 .m À2 (p < 0.01), resulting from an increase in both heart rate, from 81.3 (17.2) to 86.3 (16.5) beats.min À1 (p = 0.2), and stroke volume, from 111.8 (19.0) to 119.8 (17.9) ml (p = 0.049).Fourteen (33%) and 23 (54.8%) patients exhibited a stroke volume response > 10% and > 5%, respectively; a significant negative correlation was found between heart rate and stroke volume changes. Spinal hypotension in 20 patients was associated with an increase from baseline in cardiac index of 0.6 l.min À1 .m À2 (mean difference 11.5%; p < 0.0001). After a median [range] dose of 50 lg phenylephrine or 15 [7.5-37.5] mg ephedrine, the percentage change in cardiac index during the measurement period of 150 s was greater, and negative, in patients receiving phenylephrine vs. ephedrine, at À12.0 (7.3)% vs. 2.6 (6.0)%, respectively (p = 0.0001). The percentage change in heart rate after vasopressor was higher in patients receiving phenylephrine, at À9.1 (3.4)% vs. 5.3 (12.6)% (p = 0.0027), as was the change in systemic vascular resistance, at 22.3 (7.5) vs. À1.9 (10.5)% (p < 0.0001). Phenylephrine effectively reverses spinal anaesthesiainduced haemodynamic changes in severe pre-eclampsia, if left ventricular systolic function is preserved.

NPs provide a simple, noninvasive and complementary tool to echocardiography that can be used to assist clinicians in the assessment and management of pediatric patients with congenital heart disease in the perioperative period.