Non-invasive ventilation for acute pulmonary oedema

Extract in full from NHS Evidence: Sept 2011

Overview: Pulmonary oedema occurs when fluid leaks from the pulmonary capillary network into the lung interstitium and alveoli. It is frequently caused by disease affecting the heart’s left ventricle and may complicate the presentation of acute heart failure. The condition is a common medical emergency which requires urgent intensive treatment to reduce the risk of mortality.

Current treatment: Treatment of acute pulmonary oedema (ACPO) should be directed at reversing the specific cause, although this is not always possible.

Management is otherwise supportive and directed at improving oxygenation, perfusion and haemodynamics, and preventing further cardiac and/or renal damage.

Emergency treatment of acute heart failure includes morphine, nitrates, oxygen, diuretics and non-invasive ventilation (NIV), with urgent angiography if acute coronary syndrome is thought to be the cause. 
 
New evidence: A randomised controlled trial, carried out across 26 UK hospitals, set out to measure health utility and survival in patients with acute cardiogenic pulmonary oedema, identify predictors of outcome and determine the effect of initial treatment with NIV on outcomes (Goodacre, S et al. Emerg Med J 2011 28: 477-482).

The 1024 trial patients were randomised to continuous positive airway pressure, non-invasive positive pressure ventilation or standard oxygen therapy. During the five year study period 602 of the trial patients (58.7%) died.

The results showed that initial treatment with NIV did not lead to measurable long-term benefits for patients. However, the analysis pointed to the use of NIV as adjunctive therapy in patients with ACPO who have severe respiratory distress or whose condition does not improve with medical therapy.

Commentary: “NIV is part of the supportive strategy in ACPO and this important study showed no effect on short term mortality (7 day) when compared to standard oxygen therapy in ACPO. However this study did show that there was a clinically significant reduction in ‘treatment failures’ for NIV (i.e. a significant number of patients receiving standard oxygen therapy required rescue therapy with NIV) and a modest improvement in symptoms and metabolic disturbance. Thus NIV remains an important acute supportive strategy in ACPO in the absence of specific treatable reversible causes.

“In terms of longer term survival (1-5 years), NIV did not improve survival and perhaps this is not surprising if we consider NIV as ‘supportive’ or ‘palliative’ management in ACPO. One third of patients did not survive to one year, life expectancy was even shorter in patients who were older, had chronic obstructive pulmonary disease (COPD), previous cerebrovascular accident (CVA), or diabetes. This emphasises that end of life care discussions should be considered in patients surviving hospital admissions with ACPO.

“There was a poor response rate to the health utility questionnaires at 6 months as discussed by the authors and so response bias may have favoured those with better health. Nevertheless, compared to age-adjusted and sex-adjusted normal population the study population showed a reduction in health utility at 6 months which was especially marked in those following CVA.

“In summary this RCT highlights the poor prognosis and reduced quality of life following an emergency hospital admission for ACPO especially in elderly patients with additional comorbidities. NIV is a useful supportive or palliative strategy for an emergency hospital admission with ACPO, but does not influence long term outcomes.” – Dr Richard Venn, consultant in anaesthesia and intensive care, Western Sussex Hospitals NHS Trust.

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