You are dispatched to an unknown medical emergency near the city park. you arrive to find police on the scene and are directed to an opening in the sidewalk where a manhole cover had been removed. you note that there is blood spatter on the edge of the manhole, and at the bottom of the ladder you see a young female in jogging clothes with her back against the wall and head slumped forward, unconscious. you also hear sonorous respirations and see a visible open femur fracture that is freely hemorrhaging, and blood dripping from her face or head. what is your first concern?