Which statement about volume-cycled ventilators is true?

• A. It delivers a predetermined maximum pressure during inspiration.
• B. It relies on negative pressure to inflate the lungs.
• C. It delivers a predetermined tidal volume during inspiration and is commonly used for long-term support.
• D. The expiratory phase is actively controlled.

Answer: (C)

Volume-cycled ventilators deliver a set tidal volume during inspiration and stop once that volume is reached. This makes the inhaled volume predictable from breath to breath, which is especially helpful for maintaining consistent ventilation over the long term. The pressure needed to reach that volume can vary with changes in lung compliance or airway resistance, so there isn’t a fixed maximum pressure—unlike pressure-limited modes. These ventilators use positive pressure to inflate the lungs, not negative pressure. Expiration is typically passive, with exhalation occurring without active forcing by the machine in standard volume-cycled modes. So the statement that describes delivering a predetermined tidal volume during inspiration and being commonly used for long-term support is the correct one.