Sudden, Unexpected Pediatric Cardiac Arrest

MH rarely begins as an abrupt cardiac arrest after the use of succinylcholine. In the absence of upregulation of nicotinic skeletal muscle acetylcholine receptors,^[89] this reflects an occult myopathy that responds to succinylcholine with abrupt massive rhabdomyolysis and an associated acute rapid massive hyperkalemia.^{[90] [91] [92]} It is devastating to caregivers and family because an apparently healthy child can scarcely be resuscitated because of the difficulties in aiding redistribution of potassium to diminish hyperkalemic levels. Heroic efforts, including cardiopulmonary bypass, can be successful.^[93] These cases may respond acutely to calcium because it aids in counteracting hyperkalemia by reestablishing the ionic membrane balance in the heart and to dantrolene because of its effect in stabilizing muscle membrane permeability. Myopathic muscle continually suffers marked stress, and dantrolene may help to relieve that by attenuating calcium fluxes until more ATP is generated. Because of potential cerebral ischemia, glucose should be administered with caution. Succinylcholine continues to be valuable, because a nondepolarizing relaxant has not yet matched its advantages, but there should be precise indications for its use in young children.