Final answer:
CPR is not necessary if the patient has a pulse, as it indicates the heart is still beating. If no pulse is detected, CPR should be started immediately following proper technique and training.
Step-by-step explanation:
If the patient has a pulse, you generally do not need to start cardiopulmonary resuscitation (CPR). CPR is intended for use when a person's heart has stopped or when they are not breathing. When feeling a pulse, you are detecting the heart's contractions indicating that it is still pumping blood. If a patient has a pulse but is not breathing, you should begin rescue breathing. However if there is no pulse that is when you start CPR to manually compress the heart to maintain blood flow especially to important organs like the brain where irreversible damage can occur within minutes due to lack of blood flow.
It is critical to apply pressure correctly on the sternum to avoid causing harm, such as broken ribs or damage to internal organs which is why proper CPR training is essential for anyone who may need to perform it.