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).

The decision to commence NIV, usually in the emergency department, depends on the initial response to medication (bronchodilators given by nebulizer) and the results of arterial blood gas tests.

[2] Cystic fibrosis also causes high volumes of sputum (phlegm) which may require specialised physiotherapy assistance and sometimes the insertion of a mini-tracheostomy to clear this.

[2] In acute cardiogenic pulmonary oedema caused by decompensated heart failure, the quality of evidence is poor but studies have shown a reduced risk of death and a decreased need for tracheal intubation for both NIV and CPAP.

Professional guidelines therefore do not give a clear recommendation,[6][8] and it is suggested that NIV is only used in an intensive care unit setting where further deterioration can be managed immediately,[8] or not at all.

[6] In those who have undergone mechanical ventilation on the intensive care unit and are considered at high risk of recurrence, NIV may be used to prevent this.

In addition, in stable chronic obstructive pulmonary disease, survival seems to be improved and there might be a short term benefit of health-related quality of life.

[2] American Thoracic Society (ATS) clinical practice guidelines recommend that NIV is provided on discharge with a further sleep study assessment as an outpatient.

[11] With regards to initiation of positive pressure treatment, the ATS guidelines recommend that in people being investigated for possible obstructive sleep apnea (OSA, a related condition), measurement of arterial carbon dioxide (in high probability) or venous bicarbonate (in moderate probability) is performed to identify OHS and to determine an indication for treatment.

The brand name BiPAP/BIPAP (for Bilevel Positive Airway Pressure) has also enjoyed a degree of popularity, after an early NIV machine produced by Respironics, but its use is now discouraged.