A medical / hospital ventilator is a machine designed to move breathable air into and out of the lungs or to provide breathing for a patient who is physically unable to breathe or breathing insufficiently. The ventilator will help the patient to breathe or take over the breathing completely and will producing the right volume of gas/air. The two main categories are Non-invasive and Invasive. Freelance Surgical offers preowned ventilators from leading brands such as Datex or Smiths.