Science, medicine, and the future: Role of molecular cell biology in understanding disease

Abstract

About one quarter of the population are aged under 15 years and many of them will require anaesthesia and surgery. Several recent developments have contributed to making anaesthesia for children easier, safer, and more pleasant for the child and parents. Topical cutaneous anaesthesiaOne of the most unpleasant procedures for children in hospital is insertion of a venous cannula for induction of anaesthesia, taking blood samples, or administering fluid and drugs. To try to reduce the pain associated with the procedure a topically active local anaesthetic preparation is applied such as Emla cream (a mixture of 2.5 mg/ml of lignocaine and 2.5 mg/ml of prilocaine). To work properly Emla cream has to be applied at least an hour before the procedure, 1 2 which means it is not suitable for emergency and some day case patients. Even when applied for 60 minutes it is effective in only 65% of children, 3 although this proportion rises if it is left in place for 90-120 minutes. 4 Emla cream also causes vasoconstriction at the site of application, which can make venepuncture difficult. 5 The recent development and licensing of a topical cream made with the local anaesthetic amethocaine has greatly improved topical anaesthesia. Amethocaine has a much higher lipid solubility than Emla and penetrates the stratum corneum, the main barrier to absorption of drugs through the skin, with comparative ease. A gel containing 4% amethocaine has been shown to provide analgesia for venous cannulation in over 80% of children compared with 66% of children who had Emla cream applied for the same period. 6This makes amethocaine particularly useful in outpatient day case surgery. Amethocaine has also been found to cause erythema and vasodilatation at the site of application, which may facilitate venous cannulation. 7 SevofluraneOne of the ways in which paediatric anaesthesia differs from adult anaesthesia is that inhalational induction is used much more commonly. The characteristics of the volatile anaesthetic agent used are important. It needs to induce anaesthesia quickly, have a low incidence of complications such as coughing, laryngospasm, and hypoxia during induction, and allow rapid recovery. Until recently halothane was the most commonly used agent, and this generally results in smooth, trouble free inductions. However, a new agent, sevoflurane, is now available in Britain which has very low solubility in blood (the blood-gas partition coefficient is 0.47 compared with 2.1 for halothane). Studies have shown that it induces anaesthesia more rapidly than halothane, [8][9][10][11][12] and it is also eliminated more quickly from the blood, producing a faster recovery. [10][11][12][13][14] Sevoflurane has a pleasant smell and is the least irritant of the volatile agents to the respiratory tract. There is a low incidence of respiratory tract irritation during its use.15 16 It produces similar degrees of myocardial depression and hypotension to equipotent concentrations of halothane in children 10 and less sensitisation of the myocardium...