The Setup Went Wrong

The following volume control waveforms demonstrate severe work shifting, late cycling dyssynchrony, and active expiratory effort. In the pressure–time scalar, a pronounced drop below the baseline during the early inspiratory phase indicates significant work shifting (previously referred to as flow starvation), where the ventilator’s delivered flow does not meet the patient’s inspiratory demand.

As the inspiratory muscles relax and the expiratory muscles contract, the airway pressure rises above the baseline, producing a pressure spike consistent with late cycling—a mismatch where the set inspiratory time exceeds the patient’s neural inspiratory time.

The expiratory flow–time scalar further shows loss of the normal exponential decay, with a rapid return of flow to baseline, indicating active expiratory muscle involvement rather than passive recoil.

Additionally (though not shown in the figure), there is evidence of a secondary inspiratory effort occurring within the same mechanical inspiratory phase, visible as a subtle pressure dip in late inspiration, followed by muscle relaxation. This suggests the patient is attempting to initiate another breath before cycling, reinforcing the presence of significant patient–ventilator dyssynchrony.