<unk>  <unk>  is the use of breathing support administered through a face mask, nasal mask, or a helmet. Air, usually with added oxygen, is given through the mask under positive pressure; generally the amount of pressure is alternated depending on whether someone is breathing in or out. It is termed "non-invasive" because it is delivered with a mask that is tightly fitted to the face or around the head, but without a need for tracheal intubation (a tube through the mouth into the windpipe). While there are similarities with regard to the interface,<unk>  is not the same as continuous positive airway pressure (CPAP), which applies a single level of positive airway pressure throughout the whole respiratory cycle; CPAP does not deliver<unk>  but is occasionally used in conditions also treated with<unk> .<unk>  is used in acute respiratory failure caused by a number of medical conditions, most prominently chronic obstructive pulmonary disease (COPD); numerous studies have shown that appropriate use of<unk>  reduces the need for<unk><unk>  and its complications. Furthermore, it may be used on a long-term basis in people who cannot breathe independently as a result of a chronic condition.
Non-invasive ventilation
Negative pressure ventilator
Mechanical ventilation
Artificial ventilation
Positive airway pressure
High-frequency ventilation
Bubble CPAP
Pressure support ventilation