A high plateau pressure during ventilation most likely indicates which of the following?

• A. High lung compliance
• B. Low airway resistance
• C. Excessively large tidal volume or reduced compliance
• D. Adequate oxygenation

Answer: (C)

Plateau pressure reflects the elastic resistance of the lungs and chest wall when airflow is momentarily stopped, so it mainly indicates how easily the lungs can be stretched (compliance) rather than the resistance of the airways. A high plateau pressure means the tidal volume is distending a stiffer system or pushing it toward overdistension, which happens when the tidal volume is too large for the current compliance or the lungs’ intrinsic stiffness is increased. In other words, excessively large tidal volume or reduced compliance best explains a high plateau pressure. If the lungs were highly compliant, plateau pressure would tend to be lower, and airway resistance affects peak pressures due to flow, not plateau pressure. Adequate oxygenation doesn’t directly address plateau pressure.