A 70-year-old woman is found lying supine in severe respiratory distress. What should the EMT do first?

Elevating the patient's upper body and administering oxygen is the most appropriate first step in managing a 70-year-old woman in severe respiratory distress found lying supine. This action helps to alleviate the pressure on the diaphragm, potentially improving respiratory mechanics and comfort.

When a patient is in respiratory distress, they may have difficulty breathing due to several factors, including fluid accumulation in the lungs or airway obstruction. By elevating the upper body, gravity can facilitate easier breathing, especially if the patient has any fluid overload or issues such as congestive heart failure. Administering oxygen ensures that the patient receives the necessary supplemental oxygen to address potential hypoxemia while further assessments and interventions are planned.

Initiating treatment with basic supportive care, such as positioning and providing oxygen, is crucial before moving on to more complex interventions like ventilation assistance or further assessments. While assessing lung sounds and applying a pulse oximeter are important components of a comprehensive evaluation, those actions would typically follow immediate supportive interventions in a scenario where a patient presents with severe distress. Immediate transport without first addressing the patient's airway and respiratory status may place the patient at higher risk.