Flow Cycling in Pressure Support Mode

In pressure support mode, the cycling mechanism is known as flow cycling. In this mode, the operator sets the percentage of peak inspiratory flow as a cycling criteria. The ventilator terminates the inspiratory phase when the inspiratory flow drops to the predetermined percentage of the peak inspiratory flow.

Note: Ventilator settings, patients' inspiratory effort, and respiratory mechanics impact the peak inspiratory flow

E.g. 1: End inspiration setting (Expiratory trigger sensitivity/exp cycling) 50% and peak inspiratory flow 80 lit/min.

The ventilator ends the inspiratory phase when the inspiratory flow drops to 40 lit/ min (50% of peak inspiratory flow=50% of 80 lit/min= 40 lit/min)

E.g. 2: End inspiration setting 25% and peak inspiratory flow 80 lit/min

The ventilator ends the inspiratory phase when the inspiratory flow drops to 20 lit/ min (25% of peak inspiratory flow=25% of 80 lit/min= 20 lit/min)

E.g. 3: End inspiration setting 50% and peak inspiratory flow 50 lit/min

The ventilator ends the inspiratory phase when the inspiratory flow drops to 25 lit/ min (50% of peak inspiratory flow=50% of 50 lit/min= 25 lit/min)

Flow cycling is also known as patient cycling since the inspiratory flow is influenced by patients inspiratory effort and respiratory mechanics