Ventilators are medical devices supporting patients' breathing. These systems are lifesaving machines.

A positive pressure ventilator forces oxygen into lungs, while a negative pressure ventilator (NPV) is a less common variety that assists breating creating a vacuum effect that expands lungs and chest, pulling air into your lungs. After the inalation phase, the machine removes the lower pressure to let lungs and chest contract, helping the patinet to exhale .

Examples of NPV are the iron lung, Cuirass ventilator and jacket ventilator. Some disadvantages compared to positive pressure ventilation include:

• it is less convenient to use.
• it is less portable.
• It has a higher risk of causing upper airway blockages.

However, during the recent pandemic, NPV demonstrated to be a valuable therapy for patients with severe cases of COVID19.