What is the key intervention in the Care under fire phase?

The key intervention in the Care under fire phase is to control life-threatening hemorrhage with a tourniquet. This phase occurs in a high-threat environment where combatants must prioritize actions that immediately impact survival. The most critical factor in this scenario is to prevent exsanguination, which is the loss of blood that can rapidly lead to death.

Using a tourniquet effectively stops or significantly slows down the bleeding from an extremity injury, allowing the casualty to survive until safer conditions allow for further medical care. The focus in this phase is to not only protect the casualty but also to ensure that the rescuer can safely attend to their own protection and prepare for extraction if necessary.

In contrast, while interventions like providing oxygen or securing an airway can be very important for casualty management under other circumstances, they are secondary to managing severe hemorrhage in this particular high-risk environment. Stabilizing the spine is also crucial in many medical situations, especially in cases of spinal injuries, but it does not take precedence over immediate lifesaving measures like hemorrhage control in the Care under fire phase.