In which of the following cases might higher airway pressures be necessary to ventilate the lungs?

• A. Cardiogenic pulmonary edema
• B. All of the above
• C. Adult respiratory distress syndrome
• D. Bronchospasm

Answer: (B)

Higher airway pressures are needed when the lungs are less compliant or the airways are more resistant, so more force is required to deliver a given tidal volume and keep gas exchange going. In cardiogenic pulmonary edema, fluid in the lungs makes them stiff, reducing compliance, so increasing pressure helps expand the alveoli and improve ventilation and oxygenation. In ARDS, diffuse alveolar damage severely decreases compliance and causes alveolar collapse; higher mean airway pressures and careful use of PEEP are often necessary to recruit and keep alveoli open, again aiming to improve oxygenation while avoiding overdistension. In bronchospasm, narrowed airways raise resistance to airflow, so higher inspiratory pressures may be needed to push air through and achieve adequate ventilation. While these pressures can be helpful, they must be used with close monitoring (plateau pressures, lung mechanics) to minimize risk of barotrauma.