Final answer:
The primary intervention for a patient with signs of severe respiratory distress should be to administer high-flow oxygen therapy via facemask to stabilize oxygenation before proceeding with other interventions.
Step-by-step explanation:
The priority nursing intervention for a patient who comes into the emergency department (ED) extremely anxious, tachycardic, struggling for air, and with a moist cough productive of frothy, blood-tinged sputum is b. Administer high-flow oxygen therapy via facemask. This immediate intervention is crucial to address the patient's hypoxemia, as evidenced by the low oxygen saturation (indicated by the symptoms of the patient which resemble those of pulmonary edema or acute respiratory distress). Tachycardia and the production of frothy, blood-tinged sputum are indicative of significant respiratory compromise possibly requiring immediate oxygenation support.
Although all the listed interventions might be necessary as the situation progresses, the initial priority is to stabilize the patient's oxygenation status. Therefore, administering high-flow oxygen can help improve the patient's oxygen saturation levels and potentially stabilize their condition before additional interventions are implemented such as continuous positive airway pressure (CPAP) ventilation, or intubation and mechanical ventilation, which can be prepared for concurrently if the patient's condition does not improve.