How is Peak Inspiratory Pressure (PIP) defined?

• A. Pressure at end expiration
• B. Pressure during plateau hold
• C. Pressure at start of inspiration
• D. Pressure at end of inspiration to overcome non-elastic airways

Answer: (D)

Peak inspiratory pressure is the maximum airway pressure reached during the ventilator’s inspiratory phase. It represents the pressure needed to push air into the lungs against both the resistance of the airways (the non-elastic, frictional component) and the elastic recoil of the lungs and chest wall. Because it occurs while flow is still occurring, it captures how hard the ventilator must work to overcome airway resistance as well as lung stiffness. This is different from plateau pressure, which is measured during an inspiratory hold with no flow and reflects only lung compliance. It’s also different from end-expiration pressure (PEEP) or the pressure at the start of inspiration. The option describing the pressure at the end of inspiration to overcome airway resistance aligns with Peak Inspiratory Pressure, since the peak pressure occurs near the end of the inspiratory phase when flow is slowing and resistance plus elastic recoil determine the needed pressure.