Measured values for Ppeak and Pplateau

Peak airway pressure (Ppeak) is measured at the airway opening and is routinely displayed by mechanical ventilators. It represents the total pressure needed to push a volume of gas into the lung and is composed of pressures resulting from inspiratory flow resistance (resistive pressure), the elastic recoil of the lung and chest wall (elastic pressure), and the alveolar pressure present at the beginning of the breath

Plateau pressure (Pplateau) is the pressure value that is maintained constant during a portion of the inspiratory phase of the breath during no flow. No flow means there is no more resistive pressure to overcome, therefore plateau pressure equals alveolar pressure.

• Inspiratory hold: Manual end-inspiratory hold performed by the user
• Rapid interruption method: Short, automated end-inspiratory occlusion maneuver by the ventilator
• Least squares fit method: Computed calculation of Pplateau

Parameter (unit): Pplateau (cmH2O)

Monitoring window: Monitoring 1

Definition: Plateau or end-inspiratory pressure. The pressure measured at the end of inspiration when flow is or is close to zero.

• In volume modes when the set Pause is greater than zero.
• In non-volume modes when the end-inspiratory pressure is very stable (pressure change < 1 cmH2O over 100 ms).

Pplateau is a rough representation of alveolar pressure.

As shown by Mojoli in 2015 (Mojoli et al. Automatic monitoring of plateau and driving pressure during pressure and volume controlled ventilation. Intensive Care Medicine Experimental 2015 3(Suppl 1):A998.1​), the Pplateau monitoring parameter calculated using the LSF method gives a good estimation of the actual plateau pressure in situations where the flow at the end of inspiration is or is close to zero. Pplateau will only be shown in the monitoring parameters under such conditions. If the end-inspiratory flow is too high or the end-inspiratory pressure is unstable, the parameter will not be available (see Figure 2). However, it is also possible to measure Pplateau manually by performing an inspiratory hold maneuver (see Figure 3).

​To perform an inspiratory hold maneuver:

1. Ensure the Paw waveform is displayed.
2. Open the Hold window.
3. Wait until the Paw waveform plot restarts from the left side.
4. Wait for the next inspiration.
5. Then select Insp hold. Wait for 3 to 5 seconds, then select Insp hold or press the P&T knob again to deactivate the hold maneuver and close the window.
6. After the maneuver, the Hold window closes, and the freeze function is activated automatically.
7. Measure Pplateau by examining the points on the curve with the cursor.

Relevant devices (Standard on the HAMILTON-S1A​)​: HAMILTON-G5/S1 (sw v2.6x); HAMILTON-C3 (sw v2.0.x), HAMILTON-C6 (sw v1.0.x)