What is the Plateau Pressure?

Source::http://www.ccmtutorials.com/rs/mv/platpres.htm

The plateau pressure is the pressure applied (in positive pressure ventilation) to the small airways and alveoli. It is believed that control of the plateau pressure is important, as excessive stretch of alveoli has been implicated as the cause of ventilator induced lung injury. The peak pressure is the pressure measured by the ventilator in the major airways, and it strongly reflects airways resistance. For example, in acute severe asthma, there is a large gradient between the peak pressure (high) and the plateau pressure (normal).

In pressure controlled ventilation, the pressure limit is (usually) the plateau pressure due to the dispersion of gas in inspiration. In volume control, the pressure measured (the PAW) by the ventilator is the peak airway pressure, which is really the pressure at the level of the major airways. To know the real airway pressure, the plateau pressure which is applied at alveolar level, the volume breath must be made to simulate a pressure breath. An inspiratory hold (0.5 to 1 second) is applied, and the airway pressure, from the initial peak, drops down to a plateau. The hold represents a position of no flow.

The figure above is a waveform of a patient on volume control ventilation with a 0.8 second inspiratory hold.