Indications for noninvasive ventilation

Acute and long-term noninvasive ventilation can be used for various indications.

Acute noninvasive ventilation can be used in an acute exacerbation of chronic obstructive pulmonary disease (COPD), acute cardiogenic pulmonary oedema, hypoxaemic respiratory failure, life-threatening acute asthma, and to wean high-risk patients from invasive ventilation. See Common indications for acute and long-term noninvasive ventilation for more details on indications for acute noninvasive ventilation.

Acute noninvasive ventilation is usually administered in critical care or high-dependency units, where staff are adequately trained and close observation is possible, because risk of treatment failure, complications and subsequent need for mechanical intubation is high.

Long-term noninvasive ventilation can be used in chronic hypercapnia of any cause, obstructive sleep apnoea, obesity hypoventilation syndrome, neuromuscular disease (eg motor neurone disease), diaphragm palsy, chest wall disorders (eg kyphoscoliosis) and end-stage respiratory failure. See Common indications for acute and long-term noninvasive ventilation for more details on indications for long-term noninvasive ventilation.

Continuous positive airways pressure (CPAP) is usually preferred when treating acute cardiogenic pulmonary oedema, obstructive sleep apnoea and obesity hypoventilation syndrome. Bilevel positive airways pressure (BPAP) is usually preferred when treating hypercapnic respiratory failure due to COPD, neuromuscular or chest wall disorders, and to wean high-risk patients from invasive ventilation.

Table 1. Common indications for acute and long-term noninvasive ventilation
Indications	Benefits or details of noninvasive ventilation use
Acute noninvasive ventilation
Acute exacerbation of COPD	Can avoid the need for intubation, and reduce length of hospital stay and mortality. Recommended for COPD exacerbations associated with hypercapnic respiratory failure and acidosis, defined as pH below 7.35, and a PaCO₂ above 45 mmHg, despite optimal therapy (including oxygen therapy). BPAP is usually preferred.
Acute cardiogenic pulmonary oedema	Can improve respiratory distress and metabolic disturbance. CPAP is usually preferred. Reserve BPAP for patients failing to improve on CPAP, particularly if there is carbon dioxide retention.
Weaning high-risk patients from invasive ventilation	Useful in patients with a high risk of postextubation respiratory failure, including those with myopathy (eg prolonged stay in ICU, often recovering from a sudden medical or surgical event), pre-existing respiratory or cardiac disease, or morbid obesity. BPAP is usually preferred.
Hypoxaemic respiratory failure	High-flow nasal cannula oxygen therapy may be preferred, although evidence is limited. Consider trial of noninvasive ventilation if patient does not respond to high-flow nasal cannula oxygen therapy, although some hospitals may use noninvasive ventilation first line. Start in critical care or high-dependency unit because risk of treatment failure and subsequent need for mechanical intubation is high. Either BPAP or CPAP can be used. Some patients require invasive ventilation without first trialling noninvasive ventilation.
Life-threatening acute asthma	BPAP is usually preferred. Close observation in emergency department, critical care or high-dependency unit is recommended.
Long-term noninvasive ventilation
Chronic hypercapnia of any cause	Manage reversible factors (eg sedatives, excessive oxygen, electrolyte imbalance, endocrine abnormalities such as hypothyroidism) and optimise underlying medical condition(s) (eg COPD, heart failure) before starting noninvasive ventilation. Particularly effective for patients with COPD who remain hypercapnic several weeks following hospital admission for acute exacerbation. BPAP is usually preferred.
Obstructive sleep apnoea	Consider long-term nocturnal CPAP for patients with: severe obstructive sleep apnoea symptoms of daytime dysfunction and moderate obstructive sleep apnoea obstructive sleep apnoea and hypertension. See here for more information on CPAP for obstructive sleep apnoea.
Obesity hypoventilation syndrome	CPAP is usually preferred as initial therapy because it has similar long-term effectiveness as BPAP but is lower in cost and complexity. BPAP can be considered in patients who do not respond to CPAP.
Neuromuscular disease (eg motor neurone disease) Diaphragm palsy Chest wall disorders (eg kyphoscoliosis)	BPAP is usually preferred.
End-stage respiratory failure with hypercapnia in airway disease (eg COPD, cystic fibrosis)	Patients generally have nocturnal hypoventilation associated with a rise in PaCO₂ of more than 5 mmHg. They tolerate and demonstrate a physiological benefit with noninvasive ventilation. BPAP is usually preferred. See Noninvasive ventilation for breathlessness in palliative care for more advice.
Note: BPAP = bilevel positive airway pressure, COPD = chronic obstructive pulmonary disease, CPAP = continuous positive airway pressure, ICU = intensive care unit, PaCO₂ = partial pressure of carbon dioxide