The patient is evaluated for potentially treatable causes; a useful memory aid is "Hs and Ts": H: H ypoxia, h ypovolemia, acidosis (h ydrogen ion), h yperkalemia or h ypokalemia, h ypothermia T: T ablet or t oxin ingestion, cardiac t amponade, t ension pneumothorax, t hrombosis (pulmonary or coronary) In pediatric cardiac arrest, h ypoglycemia is another potentially treatable cause.