Which HFOV parameter is equivalent to peak inspiratory pressure in conventional ventilation?

• A. Mean airway pressure
• B. Delta P (Amplitude)
• C. Frequency (Hz)
• D. Oxygen concentration

Answer: (B)

In HFOV, ventilation occurs with a constant mean airway pressure plus rapid, tiny pressure oscillations. The element that plays the role of peak inspiratory pressure from conventional ventilation is the amplitude of those oscillations—the Delta P. This amplitude is the pressure swing above (and below) the mean; increasing it increases the driving pressure and enhances ventilation/CO2 removal, similar to raising PIP in conventional ventilation. The mean airway pressure mainly governs oxygenation by keeping the lungs inflated, frequency affects how often the oscillations happen (and influences CO2 clearance indirectly), and the oxygen concentration is about FiO2, not pressure.