Which ventilator measurement alerts the clinician to potential alveolar distention?

• A. Pplat
• B. PIP
• C. PEEP
• D. Raw

Answer: (A)

Plateau pressure is the best indicator of alveolar distention. It measures the pressure inside the alveoli during an inspiratory pause when there is no flow, so it reflects the elastic recoil the lung tissue must overcome to keep the alveoli open. If plateau pressure is elevated, the alveoli are being stretched more than intended, increasing the risk of volutrauma and overdistension. That’s why clinicians aim to keep plateau pressure around ≤30 cm H2O in most patients to minimize lung injury.

Peak inspiratory pressure includes both elastic recoil and airway resistance; a high peak can occur with things like a blocked tube or bronchospasm, even if the alveoli aren’t overdistended. PEEP is the baseline pressure at end expiration and doesn’t directly quantify the peak distending pressure the alveoli experience during inspiration. Raw reflects resistance in the airways, not the distending pressure of the alveoli itself.

So, by monitoring plateau pressure during an inspiratory hold, you’re directly assessing the distending pressure on the alveoli and the risk of alveolar overdistention.