Cardiopulmonary resuscitation (CPR) involves chest compressions and mouth-to-mouth breathing to circulate oxygenated blood to vital organs until more advanced treatment can be provided. CPR consists of 30 chest compressions followed by 2 breaths, repeating in cycles until emergency help arrives. For children, CPR is similar but uses only the heel of one hand for compressions at a rate of 100-120 per minute and a depth of at least 1/3 the chest diameter. CPR can double a victim's chance of survival from cardiac arrest.