What is a sign that a casualty requires immediate medical attention?

A casualty requiring immediate medical attention is indicated by unresponsiveness or altered mental status. This sign is critical because it suggests a potential life-threatening condition that demands prompt intervention. Unresponsiveness may indicate severe neurological issues such as traumatic brain injury, stroke, or significant shock. Altered mental status can arise from various factors, including hypoxia, head trauma, or severe dehydration, and each of these conditions poses a serious risk to the casualty's life.

In contrast, a stable breathing pattern signifies that the casualty's airway is clear and they are adequately ventilating, which is a positive sign rather than a call for immediate intervention. Severe bleeding that’s been controlled is being managed effectively and does not signify an immediate need unless bleeding resumes or other complications develop. Minor abrasions and bruises generally do not require urgent medical attention, as they are usually manageable and less serious situations. The presence of altered mental status is the most urgent indicator among the choices available, necessitating quick medical evaluation and care.