Which of the following indicates a need for immediate medical evacuation?

The indication for immediate medical evacuation is the inability to maintain an airway or breathing. This situation represents a life-threatening emergency that requires urgent intervention. In combat or emergency medical situations, the airway is the top priority because it is essential for oxygen exchange. If a casualty cannot maintain their own airway, they cannot breathe effectively, leading to a rapid decline in their condition due to inadequate oxygenation.

In contrast, minor lacerations and bruises do not necessitate immediate evacuation; these injuries are typically manageable on the scene or in a lower-level medical facility. Stable vital signs indicate that a patient is currently stable, which generally means that they do not require urgent evacuation. A presence of a headache, while it may be concerning, is not by itself an indication for immediate medical evacuation without additional concerning symptoms or signs. Therefore, the clear need for urgent action arises from the inability to maintain airway or breathing, highlighting the critical nature of this condition in trauma care.