Based on 2019 guidelines, 1 mg of epinephrine may be administered to patients every 3–5 minutes, but doses higher than 1 mg epinephrine are not recommended for routine use in cardiac arrest. If the patient has a non-shockable rhythm, the epinephrine should be administered as soon as possible. For a shockable rhythm, epinephrine should only be administered after initial defibrillation attempts have failed. Vasopressin overall does not improve or worsen outcomes compared to epinephrine. The combination of epinephrine, vasopressin, and methylprednisolone appears to improve outcomes. Some of the lack of long-term benefit may be related to delays in epinephrine use. While evidence does not support its use in children, guidelines state its use is reasonable. Lidocaine and amiodarone are also deemed reasonable in children with cardiac arrest who have a shockable rhythm. The general use of sodium bicarbonate or calcium is not recommended. The use of calcium in children has been associated with poor neurological function as well as decreased survival. Correct dosing of medications in children is dependent on weight. To minimize time spent calculating medication doses, the use of a Broselow tape is recommended.The 2010 guidelines from the American Heart Association no longer contain the recommendation for using atropine in pulseless electrical activity and asystole for want of evidence for its use.
A statistical analysis of many of these risk factors determined that approximately 50% of all cardiac arrests occur in 10% of the population perceived to be at greatest risk due to aggregate harm of multiple risk factors demonstrating that cumulative risk of multiple comorbidities exceeds the sum of each risk individually.Previous adverse cardiac events, non-sustained ventricular tachycardia (NSVT), syncope, and left ventricular hypertrophy (LVT) have been shown to predict sudden cardiac death in children. Current cigarette smokers with coronary artery disease were found to have a two to threefold increase in the risk of sudden death between ages 30 and 59. Furthermore, it was found that former smokers risk was closer to that of those who had never smoked.Functional changes in the heart such as reduced ejection fraction or cardiac arrhythmia have been shown to increase the risk of cardiac arrest and act independently from the risk factors previously mentioned. Conditions that produce these functional changes can be acquired following previous cardiac injury, or inherited through familial history of arrhythmogenic disorders. : 828

Causes and mechanisms
Sudden cardiac arrest (SCA), or sudden cardiac death (SCD), occur when the heart abruptly begins to beat in an abnormal or irregular rhythm (arrhythmia). Without organized electrical activity in the heart muscle, there is no consistent contraction of the ventricles, which results in the hearts inability to generate an adequate cardiac output (forward pumping of blood from heart to rest of the body).