The nurse anticipates that positive-end-expiratory-pressure (PEEP) will be utilized when a patient with acute respiratory distress syndrome (ARDS) is placed on mechanical ventilation for which purpose?

A. Provide for delivery of 100% oxygen to the lungs under pressure: PEEP does not specifically deliver 100% oxygen; rather, it maintains alveolar patency at end expiration. Oxygen concentration is set separately on the ventilator. B. Prevent the fibrotic infiltration of the lung tissue: PEEP does not directly prevent fibrosis. ARDS-related fibrosis is a long-term complication, and PEEP’s role is primarily mechanical, not anti-fibrotic. C. Apply positive pressure during inhalation to fully inflate the lungs: Positive pressure during inhalation is provided by the tidal volume or inspiratory pressure, not PEEP. PEEP maintains pressure at the end of exhalation, not during inspiration. D. Prevent alveolar collapse during expiration: PEEP maintains a baseline positive pressure in the lungs at the end of expiration, preventing alveolar collapse (atelectasis). This improves oxygenation, increases functional residual capacity, and reduces ventilator-induced lung injury in ARDS patients.