On a conventional ventilator, which change has the greatest impact on increasing the mean airway pressure?

• A. Increasing rate
• B. Increasing peak inspiratory pressure (PIP)
• C. Increasing inspiratory time
• D. Increasing positive end-expiratory pressure (PEEP)

Answer: (D)

Mean airway pressure is the average pressure the airways experience over a complete ventilator cycle, and it reflects how long and how high the airway pressure is maintained during breathing. The factor that raises this average the most is a higher baseline pressure kept throughout the cycle, which is what PEEP does. When you increase PEEP, the pressure in the airways stays elevated during both inspiration and expiration, so the entire pressure-time curve shifts upward. That sustained elevation raises the mean pressure more than any single spike at peak inspiratory pressure or short increases in inspiratory time or rate.

Raising peak inspiratory pressure does push the peak higher, but pressure falls back toward baseline during expiration, so the overall mean doesn’t rise as much. Extending inspiratory time increases how long the lungs stay at a higher pressure, which does raise the mean, but typically not to the extent achieved by a higher baseline PEEP. Increasing rate mainly shortens the expiratory phase, which can modestly affect the mean, but again the impact is smaller than elevating the baseline.

So, increasing PEEP has the greatest impact on mean airway pressure.