Pediatric defibrillation is not a common occurence, and of course when it does occur, the cardiac arrest is due to drowning, electrocution, drug overdose, etc. Comparatively, of course, cardiac arrest in older patients will be due to MI's or underlying arrhythmias that convert. The main difference you see when defibrillating a child is the shock dosage. It is, of course, much lower than what is given to an adult, and where an adult shock is a standard amount, in children it is measured and administered according to their weight. For example, the first shock would be 2 joules/kg according to pediatric advanced cardiac life support (PACLS) guidelines.