Grave prognostic markers include Evidence of cell lysis (serum potassium > 12 mEq / L [12 mmol / L]) Intravascular thrombosis (fibrinogen < 50 mg / dL [1.47 micromol / L]) A nonperfusing cardiac rhythm (ventricular fibrillation or asystole) For a given degree and duration of hypothermia, children are more likely to recover than adults.