Which ventilation mode measures flow and calculates volume, with flow and volume waveforms remaining constant while pressure waveform varies with compliance and resistance?

• A. Flow Controller Ventilation
• B. Volume Cycling
• C. Time Cycling
• D. Flow Limit

Answer: (A)

Flow-controlled ventilation actively sets and monitors the inspiratory flow, using a flow sensor to measure actual flow and integrate it over time to derive the delivered tidal volume. Because the inspiratory flow is regulated, the flow waveform remains essentially constant and the volume delivered can be calculated from that flow. The pressure required to deliver that flow, however, varies with the patient's mechanical properties—compliance and airway resistance—so the pressure waveform changes accordingly. This combination—constant flow, volume computed from flow, and pressure that fluctuates with compliance and resistance—fits flow-controlled ventilation best.