Which describes the primary function of a mechanical ventilator?

• A. It delivers oxygen only with no pressure.
• B. It produces a controlled flow of gas into the airways, with positive pressure that inflates the lungs.
• C. It requires frequent recalibration of FiO2.
• D. It is used only for patients with chronic respiratory failure.

Answer: (B)

A mechanical ventilator’s main job is to provide positive-pressure ventilation: it delivers a controlled flow of gas into the airways under positive pressure to inflate the lungs and support or replace the patient’s spontaneous breathing. This positive-pressure breath ensures adequate ventilation and gas exchange, and settings can be adjusted for tidal volume, rate, PEEP, and FiO2 as needed. The essence isn’t just delivering oxygen; oxygen can be given by other devices without pressurized breaths, but the ventilator specifically provides breaths that inflate the lungs. It’s used in both acute and chronic settings, not limited to chronic respiratory failure, and while FiO2 adjustments are part of its use, the primary function remains delivering ventilatory support through positive-pressure breaths.