BNF for Children 2011-2012

BNFC 2011–2012 15.2 Local anaesthesia 649Side-effects hepatotoxicity, pulmonary oedema, dizziness,weakness, and injection-site reactions includingerythema, rash, swelling, and thrombophlebitisLicensed use not licensed for use in childrenIndication and doseMalignant hyperthermia. By rapid intravenous injectionChild 1 month–18 years initially 2–3 mg/kg, then1 mg/kg repeated as required (total max. dose10 mg/kg)Chronic severe spasticity of voluntary musclesee section 10.2.2Dantrium Intravenous c (SpePharm) AInjection, powder for reconstitution, dantrolene sodium,net price 20-mg vial = £51.00 (hosp. only)15.2 Local anaesthesiaImportantThe drugs in section 15.2 should be used by experiencedpersonnel only and should not be administeredparenterally unless adequate resuscitationequipment is available.The use of local anaesthetics by injection or by applicationto mucous membranes to produce local analgesia isdiscussed in this section.See also section 1.7 (anus), section 11.7 (eye), section12.3 (oropharynx), and section 13.3 (skin).Use of local anaesthetics Local anaesthetic drugsact by causing a reversible block to conduction alongnerve fibres. They vary widely in their potency, toxicity,duration of action, stability, solubility in water, andability to penetrate mucous membranes. These factorsdetermine their application, e.g. topical (surface), infiltration,peripheral nerve block, intravenous regionalanaesthesia (Bier’s block), plexus, epidural (extradural),or spinal (intrathecal or subarachnoid) block. Localanaesthetics may also be used for postoperative painrelief, thereby reducing the need for analgesics such asopioids.Administration The dose of local anaestheticdepends on the injection site and the procedure used.In determining the safe dosage, it is important to takeaccount of the rate of absorption and excretion, and ofthe potency. The child’s age, weight, physique, andclinical condition, and the vascularity of the administrationsite and the duration of administration, must also beconsidered.Uptake of local anaesthetics into the systemic circulationdetermines their duration of action and producestoxicity.Great care must be taken to avoid accidental intravascularinjection; local anaesthetic injections should begiven slowly in order to detect inadvertent intravascularadministration. When prolonged analgesia is required, along-acting local anaesthetic is preferred to minimisethe likelihood of cumulative systemic toxicity. Localanaesthesia around the oral cavity may impair swallowingand therefore increases the risk of aspiration.Following most regional anaesthetic procedures, maximumarterial plasma concentration of anaestheticdevelops within about 10 to 25 minutes, so carefulsurveillance for toxic effects (see Toxicity and Sideeffects,p. 650) is necessary during the first 30 minutesafter injection.Epidural anaesthesia is combined with general anaesthesiafor certain surgical procedures in children.Use of vasoconstrictors Local anaesthetics causedilatation of blood vessels. The addition of a vasoconstrictorsuch as adrenaline (epinephrine) to the localanaesthetic preparation diminishes local blood flow,slowing the rate of absorption and thereby prolongingthe anaesthetic effect. Great care should be taken toavoid inadvertent intravenous administration of a preparationcontaining adrenaline, and it is not advisable togive adrenaline with a local anaesthetic injection indigits or appendages because of the risk of ischaemicnecrosis.Adrenaline must be used in a low concentration whenadministered with a local anaesthetic (but see alsoDental Anaesthesia, below). The total dose of adrenalineshould not exceed 5 micrograms/kg (1 mL/kg of a 1 in200 000 solution) and it is essential not to exceed aconcentration of 1 in 200 000 (5 micrograms/mL) ifmore than 50 mL of the mixture is to be injected. Caremust also be taken to calculate a safe maximum dose oflocal anaesthetic when using combination products. Forprescribing information on adrenaline, see section 2.7.2.For drug interactions of adrenaline, see Appendix 1(sympathomimetics).In children with severe hypertension or unstable cardiacrhythm, the use of adrenaline with a local anaestheticmay be hazardous. For these children an anaestheticwithout adrenaline should be used.Dental anaesthesia Lidocaine is widely used indental procedures; it is most often used in combinationwith adrenaline (epinephrine). Lidocaine 2% combinedwith adrenaline 1 in 80 000 (12.5 micrograms/mL) is asafe and effective preparation; there is no justificationfor using higher concentrations of adrenaline. See alsoUse of Vasoconstrictors, above.The local anaesthetics articaine and mepivacaine arealso used in dentistry; they are available in cartridgessuitable for dental use. Mepivacaine is available with orwithout adrenaline, and articaine is available with adrenaline.In children with severe hypertension or unstable cardiacrhythm, mepivacaine without adrenaline may be used.Alternatively, prilocaine with or without felypressin canbe used but there is no evidence that it is any safer.Felypressin can cause coronary vasoconstriction whenused at high doses; limit dose in children with coronaryartery disease.Cautions of local anaesthetics Local anaestheticsshould be administered with caution in children, especiallyif debilitated (consider dose reduction) or thosewith impaired cardiac conduction, cardiovascular disease,hypovolaemia, shock, impaired respiratory function,epilepsy, or myasthenia gravis. See also Administrationand Use of Vasoconstrictors, above.15 Anaesthesia