A 19-year-old male was struck in the head during a hockey game. He briefly lost consciousness, regained alertness for a short period, and is now becoming increasingly drowsy and vomiting. His right pupil is dilated and nonreactive. The patient suddenly becomes unresponsive with irregular respirations, BP 180/60, and HR 48 bpm. What should the nurse do first?

A. Increase IV fluids to improve cerebral perfusion is incorrect as the immediate priority. While maintaining cerebral perfusion is important, IV fluids alone do not address the life-threatening airway and respiratory compromise occurring in this patient. B. Notify the neurosurgeon immediately is important, but it is not the first action. The patient is showing signs of impending brain herniation and respiratory failure, so addressing the airway takes precedence over notification. C. Administer mannitol as prescribed is incorrect as an immediate action. Mannitol may help reduce intracranial pressure, but the patient must first have a patent airway and adequate oxygenation before administering medications. D. Ensure a patent airway and apply oxygen is correct because the patient is unresponsive with irregular respirations, indicating potential hypoxia and risk of respiratory arrest. According to the ABC (Airway, Breathing, Circulation) principle, airway management and oxygenation are the highest priority interventions in a patient with neurological deterioration. Once airway and oxygenation are secured, the nurse can then notify the neurosurgeon and prepare for interventions to reduce ICP, such as mannitol or surgical evacuation.