What device is used to assist breathing by automatically moving air into and out of a patient's lungs?

The device that assists breathing by automatically moving air into and out of a patient's lungs is a ventilator. Ventilators are critical in medical settings for patients who are unable to breathe adequately on their own due to various health conditions. They deliver regulated volumes of air and oxygen, ensuring that patients receive the necessary respiratory support to maintain proper oxygenation and carbon dioxide elimination.

A ventilator can be used in various situations, such as during surgery, after severe respiratory distress, or in cases of chronic respiratory failure, making it an essential tool in critical care environments. It works by creating a positive pressure to push air into the lungs during inhalation and allows for passive exhalation, thereby mimicking the natural process of breathing.

The other devices listed serve different purposes. A respirator is often used to filter out harmful substances from the air a person breathes. An oximeter measures the saturation of oxygen in the blood rather than assisting with breathing itself. An aerosol machine is used to deliver medication in the form of mist inhaled into the lungs but does not assist with the mechanical act of breathing.