CLINICAL MANAGEMENT OF THE PATIENT DISPOS ED TO DEVELOP MALIGNANT HYPERTHERMIA

Preparation for anaesthesia in the patient with a predisposition to ma lignant hyperthermia requires both organisational and clinical measure s. On the occasion of the preoperative consultation, the problem must be explained to the patient, and the need to confirm the suspected dia gnosis by means of a muscle biopsy discussed. Treatment with calcium c hannel blockers must be terminated or a changeover made to beta blocke rs. When, during the intervention, a muscle biopsy is scheduled for a halothane-coffeine contracture test, haloperidol must also be stopped. Premedication taking the form of orally administered benzodiazepine a nd avoidance of atropine is applied; in the case of children weighing 20 kg or less, rectal induction of anaesthesia using methohexital has proven useful. Premedication with dantrolene is contraindicated prior to obtaining a diagnostic muscle biopsy. If dantrolene is to be admini stered prophylactically prior to some other intervention, the short-te rm infusion (2.4 mg/kg over 20 minutes before anaesthesia induction) i s to be preferred to oral administration. Technical preparations shoul d include ensuring that the anaesthesia machine is not contaminated wi th volatile inhalation anaesthetics, and provision of capnometry and p ulse oximetry as well as a supply of dantrolene (greater-than-or-equal -to 5 mg/kg). Anaesthetic techniques of first choice are local and reg ional analgesia. When general anaesthesia is applied, the use of trigg er substances must be avoided. In the extubation and recovery phase, t he antagonisation of the continuing effects of muscle relaxants, opioi ds and benzodiazepines is permitted. Postoperative care following mino r complication-free surgery is administered in the general ward. Follo wing intraoperative malignant hyperthermia or major traumatising or hi ghly painful surgical procedures performed in a patient susceptible to malignant hyperthermia, monitoring in the ICU with testing of laborat ory parameters is indicated. If dantrolene has been administered in co mbination with non-depolarising muscle relaxants, respiratory complica tions or, in combination with calcium channel blockers, cardiac arrhyt hmias may be expected.