Which symptom indicates the absence of a heartbeat in a passenger?

The absence of a heartbeat in a passenger is best indicated by the presence of no pulse. When assessing a person's vital signs, the pulse is a direct reflection of the heartbeat; without a pulse, it is clear that the heart is not effectively pumping blood. This situation can arise due to various medical emergencies, including cardiac arrest, where the heart stops beating, leading to the absence of blood flow.

Recognizing the absence of a pulse is a critical step for flight attendants in identifying a potentially life-threatening condition, which requires immediate action, such as initiating CPR or using an Automated External Defibrillator (AED). This immediate identification can be life-saving, as it prompts the appropriate emergency response.

While symptoms like poisoning, shock, and severe bleeding can indicate serious medical issues, they do not specifically point to the absence of a heartbeat. Each of these conditions may present with varied symptoms, but they do not directly signify that the heart is not functioning or that a pulse is absent.