A flow-based trigger is typically configured relative to which reference?

• A. Flow baseline
• B. Pressure baseline
• C. Time baseline
• D. Gas baseline

Answer: (A)

Flow-based triggering relies on the steady baseline flow that the ventilator constantly maintains in the circuit. The patient initiates a breath by altering the flow, and when that change from the baseline crosses a set trigger threshold, the ventilator starts the next inspiratory phase. In other words, the reference is the flow baseline—the normal, continuous flow present when no effort is being made.

This is different from a pressure-based trigger, which uses a baseline airway pressure (like PEEP) and triggers when pressure drops a bit below that level. Time-based or other baselines aren’t used for triggering in this context. By using the flow baseline, the trigger responds directly to changes in flow caused by the patient’s effort, allowing quick and sensitive detection.