Emergency medical technicians transport a 27-year-old iron worker to the emergency department. They tell the nurse, “He fell from a two-story building. He has a large contusion on his left chest and a hematoma in the left parietal area. He has a compound fracture of his left femur and he’s comatose. We intubated him and he’s maintaining an arterial oxygen saturation of 92% by pulse oximeter with a manual resuscitation bag.” Which intervention by the nurse has the highest priority?