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This is a plain English summary of an original research article. The views expressed are those of the author(s) and reviewer(s) at the time of publication.
Non-invasive positive pressure ventilation may help people with rapidly deteriorating heart failure who become short of breath due to fluid build-up in the lungs. For people not requiring immediate mechanical ventilation using an endotracheal tube, this approach may reduce the risk of death in hospital and the need for intubation.
This review evaluated 24 trials of 2,664 adults comparing a group who received air under pressure through a mask, to a group receiving standard medical care. These types of masks are not routinely used for all people with deteriorating heart failure currently. However, this review found that they may be beneficial earlier in the progression of the condition, and this can avoid escalation of care to more invasive ventilation.
The evidence was not strong enough to say that the techniques shortened hospital stay or reduced heart attacks.
Why was this study needed?
There are more than 580,000 people diagnosed with heart failure in the UK, and there are thought to be thousands more who are living with the condition. In 2017/18, there were 57,926 admissions for people with deteriorating heart failure that had caused pulmonary oedema.
Symptoms of pulmonary oedema include difficulty breathing, shortness of breath when lying down, cough and fatigue. Medications aim to reduce the fluid, increase the blood supply to the heart and treat the underlying cause.
This Cochrane review aimed to investigate whether adding non-invasive positive pressure ventilation to usual medical care in adults in this situation reduces rates of deaths, acute myocardial infarction (heart attacks), hospital length of stay or the need for intubation for mechanical ventilation. The researchers wanted to evaluate the impact of new literature available since the last version of this review, first published in May 2013.
What did this study do?
This systematic review and meta-analyses evaluated 24 parallel-design randomised controlled trials which compared non-invasive positive pressure ventilation to standard medical care in 2,664 adults with acute cardiogenic pulmonary oedema. Their average age was 73.
Ventilation could be received nasally or using a face mask supplying pressurised air using two techniques: via continuous positive airway pressure or via bi-level positive airway pressure, a two-level variation.
The studies were conducted in 14 countries, three of them in the UK. They varied in size from eight to 1,069 participants. Where clear, the follow-up period ranged from one to 41 days. Ten studies were in the emergency department and eight in intensive care.
The researchers reported lack of blinding and inconsistent reporting of outcomes which should be kept in mind when interpreting the results, though blinding is unlikely to have been possible in trials of this intervention in this setting.
What did it find?
- Non-invasive positive pressure ventilation may reduce hospital mortality from 17.6% to 11.4% (risk ratio [RR] 0.65, 95% confidence interval [CI] 0.51 to 0.82; 2,484 adults, 21 studies, low quality evidence).
- Fewer people needed an endotracheal tube for mechanical ventilation if they had used non-invasive positive pressure ventilation first – 15.4% needed intubation following standard care compared with 7.5% after the non-invasive technique (RR 0.49, 95% CI 0.28 to 0.62; 2,449 adults, 20 studies, moderate-quality evidence).
- No difference was observed for the use of non-invasive positive pressure ventilation compared with standard medical care for the incidence of acute myocardial infarction, which occurred in 42.1% of people on standard care compared with 43.3% on non-invasive techniques or in length of stay.
- The main adverse effect was discomfort from wearing the mask. Other events, such as swelling of the stomach, were rare.
What does current guidance say on this issue?
NICE 2014 guidelines do not recommend routine use of non-invasive positive pressure ventilation in individuals presenting with acute cardiogenic pulmonary oedema.
The guidelines suggest that in severe cases, for example, when a person with acute heart failure has particular difficulty breathing, respiratory failure or reduced consciousness, that ventilation should be considered without delay.
What are the implications?
The findings support consideration of broader indication for non-invasive positive pressure ventilation in deteriorating patients with heart failure as it is relatively safe and may improve mortality rates.
It remains unclear, from this research, at what point it should be started and which of the non-invasive positive pressure ventilation techniques might be best.
Given the large number of admissions for acute heart failure each year, and the need for resources and anaesthetist supervision, there could be resource implications if these techniques are to be used earlier on. Reduced need for more invasive mechanical ventilation, such as intubation, will be favoured by patients.
Citation and Funding
Berbenetz N, Wang Y, Brown J et al. Non-invasive positive pressure ventilation (CPAP or bilevel NPPV) for cardiogenic pulmonary oedema. Cochrane Database Syst Rev. 2019;4:CD005351.
Cochrane UK and the Heart Cochrane Review Group are supported by NIHR infrastructure funding.
Bibliography
British Heart Foundation. Statistics factsheet - UK. London: British Heart Foundation; 2019.
NHS Digital. Hospital admitted patient care activity, 2017-18: diagnosis. London: Department of Health and Social Care; 2018.
NICE. Acute heart failure: diagnosis and management. CG187. London: National Institute for Health and Care Excellence; 2014.
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