Which symptom indicates cardiac arrest?

Cardiac arrest is a critical medical condition defined by the cessation of effective heart function, which leads to the absence of circulation and inadequate blood flow to vital organs. In this context, the indication that a patient is unresponsive and not breathing is a direct sign of cardiac arrest. When a person is unresponsive, they show no signs of consciousness or awareness, which signifies a serious impairment of brain function and overall bodily distress. Additionally, the absence of breathing indicates that oxygen is not being supplied to the body, another key factor in determining cardiac arrest.

The other scenarios present conditions where the patient still shows some level of responsiveness or breathing, indicating that cardiac arrest has not occurred. For example, if the victim is responsive and breathing, they are clearly not in cardiac arrest. Similarly, an unresponsive but breathing victim may still have some level of cardiac function, meaning cardiovascular support might be required but does not reflect full arrest. If the victim is alert but has ineffective breathing, this points to a respiratory issue rather than complete cardiac failure. Thus, the only situation representing a full cardiac arrest occurs when someone is unresponsive and not breathing.