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Recruitment to Inflation Ratio

Lung Recruitability and Airway Opening Pressure

To test recruitability the PEEP must be changed from a higher PEEP to a lower level of PEEP (ideally by 10 cm H2O). Example: 15 cm H2O to 5 cm H2O. Addtionally, Volume Assist Control should be used. PLEASE USE A 0.3 SECOND INSPIRATORY PAUSE SETTING TO MEASURE PLATEAU PRESSURE. DO NOT PERFORM A MANUAL INSPIRATORY PAUSE. (Performing a manual inspiratory pause that is too long can often lead to erroneously low plateau pressure readings)

A test for Airway Closure should be done before this recruitability test. Please input the value into this form (instructional video for performing the test is at the end of this page).

The 'High PEEP' of the R/I ratio maneuver should be ideally AT LEAST 5 cm H2O above AOP provided Pplat is < 30 cm H2O. Continue to use a delta pressure of 10 cmH2O (even though it may cross the AOP) to be consistent with the expiratory driving pressure used in the study. (Reference)

Reduce the respiratory rate to 6-8 bpm to ensure enough time to exhale when PEEP is dropped.

Perform the following steps (see the video demonstration below):

  1. Input the exhaled volume at high PEEP with the respiratory rate set to 6-8 bpm
  2. Change to the lower PEEP ( do not do a gradual decrease), observe the exhaled volume when the PEEP changes from high to low!
  3. Look at the plateau pressure (some ventilators it would be the end-inspiratory pressure) measured by the ventilator with 0.3 second inspiratory pause setting (as shown in the video at the bottom of this page).

Note: High PEEP needs to be higher than AOP.

Airway Opening Pressure
Leave it empty if no airway closure
cm H2O
High PEEP
cm H2O
Set Tidal Volume (VT)
ml
VT exhaled @ high PEEP
ml
Low PEEP
cm H2O
VT exhaled from high to low PEEP
ml
Plateau Pressure (at low PEEP)
cm H2O

{{ recruitmentRatio }} {{ recruitmentRatio }}

Recruitment to Inflation Ratio

The value below is the ratio between the compliance of the recruited lung to that of the respiratory system.
Values >= 0.5 suggest more potential for lung recruitment with respect to lung inflation.

Reference Videos

Airway Opening Pressure Servoi

Recruitability Maneuver

Airway Opening Pressure PB980

Airway Opening Pressure PB840

This calculator is ideal for education and simulation purposes. It DOES NOT replace clinical or professional judgement. Use at your own discretion.

Calculator created by Thomas Piraino RRT in collaboration with Lu Chen MD