In a patient with ARDS showing increased oxygen requirements and decreased lung compliance with bilateral fluffy infiltrates, which ventilator adjustments are most appropriate?

• A. Increase VT to 500 mL, decrease f to 10 breaths/min, decrease PEEP to 5 cm H2O
• B. Decrease VT to 250 mL, increase f to 15 breaths/min, increase PEEP to 15 cm H2O
• C. Maintain VT, increase f, maintain PEEP
• D. Increase VT to 600 mL, increase f to 20 breaths/min, increase PEEP to 20 cm H2O

Answer: (B)

In ARDS with reduced lung compliance and bilateral infiltrates, the ventilator strategy should protect the lungs while improving oxygenation. That means using a low tidal volume to prevent overdistension and barotrauma, while maintaining adequate ventilation by increasing the respiratory rate to preserve minute ventilation if tidal volume is reduced. At the same time, applying higher PEEP helps recruit collapsed alveoli and keeps them open, which improves oxygenation in stiff lungs.

So the best adjustment is to lower the tidal volume, raise the respiratory rate to maintain ventilation, and increase PEEP to about recruit and support open airways. Increasing tidal volume or lowering PEEP would worsen lung injury or oxygenation, while keeping tidal volume the same without boosting PEEP wouldn’t address the poor oxygenation seen with noncompliant lungs.