What limit variable controls volume and flow during inspiration?

• A. Time Control
• B. Volume Control
• C. Pressure Control
• D. Flow Control

Answer: (B)

Setting a tidal volume means you specify how much air the patient should receive with each breath. In volume-controlled ventilation, the ventilator uses that volume target to drive the inspiratory flow and deliver air until the set volume is reached within the chosen inspiratory time. Because the goal is a fixed amount of air, the volume target also dictates how much flow is needed to reach it, shaping the inspiratory flow accordingly.

Time control would only fix how long the breath lasts, which can influence volume but doesn’t guarantee a specific amount. Pressure control limits the pressure and leaves the resulting volume to depend on lung mechanics, so volume isn’t directly controlled. Flow control sets a maximum flow but doesn’t ensure a particular tidal volume.