A ventilator is a machine that helps a person breathe or breathes for the person, controlling and monitoring the amounts of air and oxygen flowing into the person's lungs. Ventilators may be used for people who have serious breathing conditions such as asthma, cystic fibrosis, and chronic obstructive pulmonary disease (COPD).

Doctors typically attach a ventilator to a tube they have inserted into the person's windpipe (trachea) through the person's mouth or nose. If the person needs the ventilator for a long period of time, the surgeon may make an opening directly in the trachea (tracheostomy) and place the tube through this opening.