The definition of a child for CPR:
A child is from 1 year of age to puberty. Signs of puberty include chest or underarm hair in males and any breast development in females. If you are in doubt, provide emergency care as if the person is an adult.
Children usually have healthy hearts. Breathing trouble is often the cause of a child needing CPR. Some other causes are drowning, choking, trauma, and electrical injury.
Use one hand or two to compress the chest.
Compress the chest at least one-third the depth of the chest, or about 2 inches on the lower half of the breastbone at a rate of 100-120 compressions per minutes.
If you are alone and do not have a phone nearby, provide 5 sets of 30 compressions and 2 breaths of CPR before leaving to phone 911. Return to the child and continue CPR.