Identifying Reverse Trigger in Volume Control Mode

These breaths are initiated by the ventilator (time-triggered). An observable change in the pressure-time curve occurs during late inspiration, where the pressure waveform returns towards the baseline without maintaining a plateau. This suggests that neural inspiration begins after passive mechanical inflation, a phenomenon known as reverse triggering. Neural inspiration extends into the expiratory phase, causing an upward distortion of the expiratory flow-time curve (where inspiratory effort impedes expiratory flow).

Red dotted line shows normal waveform/ expected shape of scalars in the absence of reverse triggering.

NOTE: Early cycling can also result in an expiratory flow-time curve resembling reverse triggering. However, the key distinction lies in the initiation of the breath: in early cycling, the patient initiates the breath, whereas in reverse triggering, the breath is initiated by the machine.