ABSTRACT
The range of paediatric patients is very broad from the tiny preterm infant with immature organ function to the teenager who is (in pharmacological terms) an adult. Organ function matures during the first year of life but differences from adults in regional blood flow, body composition, enzyme activity, integrity of the blood-brain barrier and development of the central nervous system (CNS) mean that extrapolations from adult dosing are inaccurate. Healthy young children often need a relatively high induction dose of intravenous agent per unit of body weight and for total intravenous anaesthesia (TIVA) maintenance infusion rates often need to be higher than the weight-corrected
dose for adults. In contrast, the immature neonate, the critically ill child or those with major organ failure may need considerably reduced doses of intravenous anaesthetic agents and care is particularly needed in children receiving vasodilator medication and with certain forms of congenital heart disease. Allergic reactions to intravenous agents or their solubilising vehicles can occur unexpectedly but some can be prevented by a careful preoperative history (e.g. allergy to egg protein and propofol emulsion). In some medical conditions certain intravenous agents are specifically contraindicated, such as barbiturates in porphyria, but, in contrast, intravenous anaesthesia without volatile anaesthetic agents may be the technique of choice in the child susceptible to malignant hyperthermia. Drugs with
Introduction 169 Basic developmental pharmacology of intravenous
induction agents 170
Properties and doses of individual drugs in paediatrics 174 Total intravenous anaesthesia 178 References 181
sedative properties all potentiate each other’s sedating and CNS depressant effects and this can be used to allow a reduction in the dose of each individual agent and possibly, therefore, reduce adverse effects of each. Titration to clinical endpoints rather than strict dosing by formula is advisable to allow for wide interindividual variation in pharmacokinetics (i.e. what the body does to the drug) and pharmacodynamics (i.e. what the drug does to the body). Electronic monitoring may be useful but has not yet been well validated in paediatrics.
