During positive pressure mechanical ventilation, PEEP (positive end-expiratory pressure) is added. The primary physiological benefit of PEEP in ARDS management is:

• A Reduction of tidal volume requirement
• B Prevention of alveolar derecruitment and improvement of functional residual capacity ✓
• C Reduction of intracranial pressure
• D Enhancement of cardiac output by reducing venous return

Explanation

PEEP maintains airway pressure above atmospheric at the end of expiration, preventing alveolar collapse (derecruitment) between breaths and recruiting previously collapsed alveoli. This increases functional residual capacity (FRC), improves ventilation-perfusion matching, reduces intrapulmonary shunt, and allows reduction of FiO2 while maintaining adequate oxygenation in ARDS. High PEEP reduces cardiac output by increasing intrathoracic pressure and impeding venous return (the opposite of option D). PEEP also increases ICP slightly and must be used cautiously in patients with raised intracranial pressure.

Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.