Which cycling terminates breath when a preset inspiratory time (Ti) is reached?

• A. Time Cycling
• B. Pressure Cycling
• C. Volume Cycling
• D. Cycle Variable

Answer: (A)

Ending inspiration after a fixed duration is time cycling. The ventilator starts the breath and runs a timer; when the preset Ti is reached, it switches to expiration regardless of how the pressure or flow is behaving. This yields a predictable inspiratory time and I:E ratio. Other termination methods exist—pressure cycling ends when a target pressure is reached, volume cycling ends after delivering a set tidal volume, and flow cycling ends when inspiratory flow falls below a threshold—but they do not rely on a timed interval like time cycling.