Reverse Trigger and 1:2 Entrainment

The second and fourth breaths are machine initiated mandatory breaths (No pressure drop before inspiration)

The first and third breaths are considered mandatory breaths, but there is noticeable evidence of inspiratory muscle activity (P insp mus) during the second half of the inspiratory phase and early expiratory phase. This occurrence is referred to as reverse triggering, which involves the passive inflation of the lungs leading to neural activation of the diaphragm. This pattern repeats in alternating breaths, known as 1:2 entrainment.

Activation of inspiratory muscles during a mandatory breath can lead to:

-Decreased peak inspiratory pressure

-Deformation of the inspiratory phase

-Loss of plateau phase

-Slight pressure drop below the baseline during early expiration

-Decreased peak expiratory flow

-An upward deflection in the expiratory flow-time scalar (decreased expiratory flow)

The morphology of the inspiratory flow-time scalar is not affected by Pmus because the flow pattern is predetermined/ fixed in volume control mode.

When utilizing an esophageal balloon catheter, one can detect a decrease in pressure within the esophageal pressure waveform, occurring simultaneously with the initiation of neural activity during the latter part of the inspiratory phase of a mandatory breath.