Plateau pressure is an important parameter in ventilator management. Which statement correctly describes its measurement and purpose?

• A. Measured during expiration; reflects airway resistance
• B. Measured during inspiration with a normal inspiratory ramp; equals peak airway pressure
• C. Measured during an inspiratory hold; reflects alveolar pressure and risk of volutrauma; aim ≤30 cm H2O
• D. Measured continuously; no specific target

Answer: (C)

Plateau pressure is the pressure in the alveoli when there is no flow, which is why it’s measured with a brief inspiratory hold at the end of inspiration. This静 static reading isolates the elastic recoil of the lung from airway resistance and airflow, giving a direct read on the distending pressure the lung tissue actually experiences.

This makes it the best measure for guiding safe ventilation. If plateau pressure is high, the alveoli are being distended too much, increasing the risk of volutrauma (and barotrauma). Therefore, the goal is to keep the plateau pressure at or below about 30 cm H2O to minimize this risk.

It’s distinct from peak inspiratory pressure, which includes resistive pressure from airway resistance during flow. The plateau pressure reflects alveolar pressure with no flow, not the dynamic peak. It isn’t measured during expiration, and it isn’t intended to be a continuously read number without a target—there is a specific aim to maintain it under the 30 cm H2O threshold.