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People admitted to hospital with a severe exacerbation of chronic obstructive pulmonary disease (COPD) were 46% less likely to die if they received non-invasive ventilation. Only 12% of those receiving non-invasive ventilation needed subsequent invasive ventilation via a tube, compared to 34% of those who had usual care.

This review identified 17 trials of adults with a severe acute exacerbation of COPD with high carbon dioxide levels. Trials compared usual care, including steroids and antibiotics with usual care plus non-invasive ventilation, which delivers air at high pressure via a mask. Airways are forced open and respiratory muscles can rest.

This updated review shows benefits of immediate treatment with non-invasive ventilation for people with COPD admitted with respiratory failure. The results do not apply to patients in respiratory failure from other causes.

Acceptability of the treatment to patients, quality of life and cost measures need further exploration.

Why was this study needed?

Chronic obstructive pulmonary disease (COPD) affects about three million people in the UK, mostly smokers over 40 years old. It accounts for about 30,000 deaths annually and costs the NHS £1.9 billion per year.

COPD is an irreversible condition. It incorporates emphysema (damage to the lung air sacs), and chronic bronchitis (long-term airways inflammation). An exacerbation of COPD causes severe breathlessness, confusion, low blood oxygen levels and can cause high carbon dioxide levels.

Non-invasive ventilation pushes air into the lungs via a facemask. Unlike invasive ventilation, patients are not sedated and do not need a tube inserted into the windpipe. There is a lower risk of complications, such as pneumonia than with invasive ventilation.

Non-invasive ventilation is increasingly being used for people admitted to hospital with acute exacerbations of COPD in severe respiratory failure. This review aimed to gather evidence on the effectiveness of this approach.

What did this study do?

This systematic review found 17 randomised controlled trials involving 1,264 adults admitted to hospital with a severe exacerbation of chronic obstructive pulmonary disease. This was defined as a low blood pH (less than 7.35) and high levels of carbon dioxide (6kPa or more).

Non-invasive ventilation was delivered with a Bilevel Positive Airway Pressure machine on a hospital ward. Usual care involved typical medical treatment without ventilation. People with pneumonia were excluded.

The review looked primarily at mortality during the hospital admission and the need to insert a tube into the windpipe.

The evidence was rated as moderate quality. The intervention made blinding difficult although this was unlikely to affect the primary objective outcomes. Treatment duration and the type of ward setting varied somewhat between studies.

What did it find?

  • Participants who received ventilation were 46% less likely to die during that hospital admission than those who just received usual care (risk ratio [RR] 0.54, 95% confidence interval [C.I] 0.38 to 0.76). During the 10% (42/434) of participants who received ventilation and usual care died compared with 18% (77/420) who received usual care. This pooled analysis was from 12 studies.
  • Intubation was required by 12% (67/559) people who received ventilation, compared with 34% (186/546) of those with usual care alone (RR 0.36, 95% CI 0.28 to 0.46). These results were from 17 studies.
  • Pooled results from ten studies involving 888 participants found that people who initially received ventilation stayed in the for on average 14.1 days compared to 17.5 days for usual care alone (mean difference -3.39, 95% CI -5.93 to -0.85).
  • Six studies, 346 participants, found that people were less likely to tolerate non-invasive ventilation than usual care. This result given the nature of ventilation delivery (risk difference 0.11, 95% CI 0.04 to 0.17).

What does current guidance say on this issue?

NICE 2010 guidance recommends using non-invasive ventilation as the treatment of choice for persistent respiratory failure despite optimal medical therapy. It should be delivered in a dedicated setting with trained staff who are experienced in its use. There should be a clear plan covering what to do in the event of deterioration and ceilings of therapy should be agreed. The 2008 guideline from the Royal College of Physicians, British Thoracic Society and Intensive Care Society recommends that non-invasive ventilation should be considered if the blood acidity remains low despite a maximum of one hour of standard medical therapy.

What are the implications?

This review suggests that prompt non-invasive ventilation during admission could save lives and avoid invasive ventilation. This may have training implications as it should only be delivered by staff proficient in its use and who understand its limitations. There may also be issues around availability of Bilevel Positive Airways Pressure machines.

The results don’t apply to people who are coming off invasive ventilation therapy or those in respiratory failure not due to chronic obstructive pulmonary disease.

There was no cost analysis, but reduced hospital stays suggest potential financial savings. It would be useful to see patient-centred outcomes in the future including the acceptability of these devices and quality of life.


Citation and Funding

Osadnik CR, Tee VS, Carson-Chahhoud KV, et al. Non-invasive ventilation for the management of acute hypercapnic respiratory failure due to exacerbation of chronic obstructive pulmonary disease. Cochrane Database Syst Rev. 2017;7:CD004104.

This project was funded by the National Institute for Health Research via Cochrane infrastructure funding to the Cochrane Airways Group.



British Lung Foundation. Estimating the economic burden of respiratory illness in the UK. London: British Lung Foundation; 2017.

National Clinical Guideline Centre. Chronic obstructive pulmonary disease: Management of chronic obstructive pulmonary disease in adults in primary and secondary care. London: National Clinical Guideline Centre; 2010.

NCEPOD. Acute Non-Invasive Ventilation: Inspiring Change. London: National Confidential Enquiry into Patient Outcome and Death; 2017.

NHS Choices. Chronic obstructive pulmonary disease (COPD). London: Department of Health; 2016.

NICE. Chronic Obstructive Pulmonary Disease in over 16s: diagnosis and management. CG101. London: National Institute for Health and Care Excellence; 2010.

Patient. Chronic Obstructive Pulmonary Disease. Leeds: Patient; 2015.

Produced by the University of Southampton and Bazian on behalf of NIHR through the NIHR Dissemination Centre


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Bilevel Positive Airways Pressure involved delivering air at high pressure via a nasal cannula (a tube in the nose) or a facemask. It increases oxygen levels and helps the wearer breathe out more carbon dioxide. It also helps to rest respiratory muscles. 
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