These are patient-triggered breaths, identified by a drop in pressure before inspiration. In this case, the patient's inspiratory effort persists even after the ventilator cycles to exhalation, leading to immediate triggering of another breath- resulting in a double trigger. This occurs when the patient's neural inspiratory time is longer than the ventilator's set inspiratory time

The following waveform illustrates three consecutive breaths, each with distinct morphologies. On this ventilator (Maquet, Getinge), patient-triggered breaths are marked in pink at the initial rise in pressure and flow, corresponding to pressure or flow triggering. In this case, flow triggering was used. The breaths appear to be patient-triggered, as suggested by a small negative deflection in airway pressure preceding inspiration and the pink marking on the flow–time scalar.

There is always some delay between the onset of the patient's inspiration and mechanical inflation- a lag period known as trigger delay. It is usually less than 100 milliseconds. Late trigger increases patient's work of breathing. Late/delayed trigger: Trigger delay > 100 milliseconds

In pressure control mode, airway pressure remains constant throughout the inspiratory phase. However, if the patient attempts to exhale before the set inspiratory time ends, the pressure transiently rises above the set inspiratory pressure. This occurs when the patient’s neural inspiratory time is shorter than the ventilator’s set inspiratory time—a phenomenon known as late cycling . Late cycling can be recognized on ventilator waveforms by a pressure spike  on the pressure–t

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 i

These are machine-triggered mandatory breaths. During mid-inspiration, a pressure drop appears on the pressure-time scalar along with a corresponding spike on the inspiratory flow-time scalar. This indicates the onset of neural inspiration induced by passive mechanical inflation - a phenomenon known as reverse triggering. The patient's neural effort persists beyond the set inspiratory time, triggering another breath during the expiratory phase and resulting in a double trigge