What is plateau pressure and why should it be kept low?

• A. Plateau pressure is the alveolar pressure during an inspiratory hold; keep ≤30 cm H2O to minimize ventilator-induced lung injury.
• B. Plateau pressure is the peak airway pressure during inspiration; keep ≤60 cm H2O.
• C. Plateau pressure is the pressure in the pleural space; keep at 5 cm H2O.
• D. Plateau pressure is the mean airway pressure; keep below 15 to prevent barotrauma.

Answer: (A)

Plateau pressure is the pressure inside the alveoli at the end of a full inspiration during an inspiratory hold when there is no gas flow. This momentary pause removes the pressure effects of airway resistance, so the measurement reflects the elastic distending pressure of the lungs and chest wall—the true pressure acting to open the alveoli.

Keeping plateau pressure low is important because high plateau pressures indicate the lungs are being overdistended, which raises the risk of ventilator-induced lung injury (barotrauma and volutrauma). The commonly used target is to keep this pressure at or below about 30 cm H2O to minimize alveolar damage while still delivering adequate ventilation.

If plateau pressure is too high, adjust by reducing tidal volume (for example, around 6 mL/kg predicted body weight) and/or optimizing PEEP to improve compliance. This approach lowers the distending pressure on the alveoli without simply increasing overall pressures.

It’s different from peak airway pressure, which includes resistance in the airways and tends to be higher when there’s bronchospasm or secretions. Plateau pressure is measured during a no-flow hold and reflects alveolar pressure, not mean airway pressure or pleural pressure.