What is the criteria for starting CPR in an unconscious adult?

The criteria for initiating CPR in an unconscious adult hinges on the absence of both breathing and a pulse. When an individual is unresponsive, it is crucial to quickly assess their vital signs. If there is no breathing, indicated by an inability to see chest rise or hear breath sounds, and no pulse can be felt, this indicates that the body is not functioning properly and requires immediate life-saving measures.

Starting CPR in this situation is critical because it helps maintain blood flow to vital organs, increasing the chances of survival until further medical assistance arrives. It is an essential response in cases of cardiac arrest, where the heart fails to pump blood effectively. The absence of these vital functions signals the need for immediate intervention to prevent permanent damage or death.

The other options do not align with the established guidelines for performing CPR. For instance, the presence of breathing and pulse indicates that the individual is alive and does not require CPR, while only transporting to a hospital or waiting for a defibrillator would introduce unnecessary delays in providing essential life support. Thus, recognizing the signs of unresponsiveness coupled with respiratory and cardiac failure is key to initiating the appropriate emergency response.