A nurse is caring for a client who develops a pulmonary embolism. Which of the following interventions is the priority for the nurse to take?

Choice A rationale Administering an IV infusion like Lactated Ringer's addresses potential hypovolemia or shock but is not the immediate priority for a client with pulmonary embolism (PE). PE primarily causes an obstruction of pulmonary blood flow, leading to ventilation-perfusion (V/Q) mismatch and resulting in hypoxemia, which must be addressed first. Choice B rationale IV morphine can alleviate the pleuritic chest pain and anxiety associated with a pulmonary embolism by depressing the central nervous system and reducing myocardial oxygen demand. However, managing pain is a secondary intervention to the life-threatening impairment of oxygenation. Choice C rationale Initiating cardiac monitoring is vital for detecting potential complications such as dysrhythmias or right heart strain secondary to increased pulmonary vascular resistance. Nevertheless, the immediate threat to life is profound hypoxemia due to the massive V/Q mismatch, making oxygen delivery paramount. Choice D rationale Beginning oxygen therapy is the priority intervention because a pulmonary embolism obstructs blood flow to the alveoli, causing a severe ventilation-perfusion (V/Q) mismatch and hypoxemia. Supplemental oxygen directly increases the PaO_2 and SaO_2, which are essential for maintaining adequate tissue oxygenation and preventing organ damage.