When should a first responder initiate CPR?

Initiating CPR is critical for a patient who is in cardiac arrest, and the key factor that dictates when to start CPR is the patient’s level of responsiveness. If the patient is unconscious and unresponsive, it indicates that they are likely not breathing adequately or not at all, and there is a high risk of cardiac arrest. The absence of responsiveness typically signals that the body's vital systems are failing, and immediate intervention is required to attempt to restore circulation and breathing.

In this context, beginning CPR can help maintain blood flow to vital organs until advanced medical personnel can arrive. This prompt action can significantly improve the chances of survival and reduce the risk of long-term damage to the brain and other organs due to lack of oxygen.

Other options would not prompt the initiation of CPR. For instance, waiting for the patient to be breathing or having a pulse contradicts the purpose of CPR, which is to assist a person who is experiencing such a crisis. Similarly, calling for emergency help is essential, but it should not delay the immediate start of CPR when the patient is unresponsive, as help may take time to arrive. Therefore, the critical factor for initiating CPR is the patient's unresponsiveness.