When ventilated with volume assist-control, plateau pressure is 42 cm H2O after an inspiratory hold; what should you do first?

• A. Decrease the tidal volume
• B. Increase FiO2
• C. Increase PEEP
• D. Disconnect ventilation

Answer: (A)

High plateau pressure signals overdistension or reduced lung compliance with the current tidal volume. In volume assist-control, the tidal volume is fixed, and plateau pressure reflects the pressure needed to deliver that volume at the end of inspiration. When plateau pressure is as high as 42 cm H2O, the safest first step is to lower the tidal volume to reduce alveolar distension and bring plateau pressure toward a safer range (generally ≤30 cm H2O). After lowering tidal volume, reassess ventilation: adjust the minute ventilation with the respiratory rate if CO2 rises, and manage oxygenation with FiO2 and, if needed, PEEP—but increasing PEEP would typically raise plateau pressure further. Disconnecting ventilation would stop support and is not appropriate.