Which action should you first take when assessing an unresponsive adult patient who is breathing and has a pulse?

When assessing an unresponsive adult patient who is breathing and has a pulse, performing a primary assessment and emergent interventions is the most critical first step. The primary assessment involves checking the airway, breathing, and circulation—often referred to as the ABCs. This is vital to determine if the patient's airway is open and if they are breathing adequately, as these aspects are essential for ensuring their immediate safety.

Once the primary assessment is completed and any emergent interventions (such as ensuring that the airway is clear or providing oxygen if needed) are conducted, you can then proceed to further actions, such as calling for advanced medical support. This systematic approach ensures that the most pressing needs of the patient are addressed right away.

Waiting to activate EMS until after completing your assessment could result in delays that may compromise the patient's condition, especially if their situation worsens. Placing the patient in a supine position is appropriate when managing someone who is unresponsive but requires further assessment before doing so; therefore, it's not the very first action to take. Moreover, calling for advanced medical support immediately could also distract from the necessary primary assessment that is crucial in providing effective care.