Succinylcholine-induced cardiac arrest in children with undiagnosed myopathy.

Two paediatric cases are reported in which unexpected, life-threatening arrhythmias occurred. Routine induction of general anaesthesia with thiopentone, 5 mg.kg-1, in one and with halothane in the other, and succinylcholine 1.25-1.5 mg.kg-1 i.v. was followed by the development of wide complex tachyarrhythmia with hypotension in the first case and asystole in the second case despite pre-treatment with atropine in both cases. The first patient was resuscitated with tracheal intubation, 100% oxygen, manual ventilation and intravenous lidocaine and bicarbonate. The second patient required intubation, manual ventilation, 12 min of CPR and i.v. calcium, epinephrine and bicarbonate, as well as DC counter shock. Neither patient received dantrolene. Early recovery in both patients was uneventful with no neurological sequelae. Subsequent investigations revealed the presence of a dystrophin-deficient muscular dystrophy, Duchenne muscular dystrophy and Becker muscular dystrophy respectively, previously unsuspected, in both patients. The aetiology of the observed arrhythmias was presumably hyperkalaemia, secondary to succinylcholine-induced rhabdomyolysis. It is suggested that when faced with sudden, life-threatening arrhythmias following succinylcholine at induction of anaesthesia for paediatric patients, clinicians should include occult myopathy in the differential diagnosis, and thus consider the aggressive management of hyperkalaemia in addition to basic resuscitative efforts.