Non-invasive ventilation for acute cardiogenic pulmonary oedema
September 27, 2010 Leave a comment
Blog Post by Mr Tim Case MPhil MA (Cantab) Medical Student, Hughes Hall, University of Cambridge, Cambridge, CB1 2EW, UK, and Dr Stephen T Webb MB BCh BAO FRCA EDIC, Consultant in Anaesthesia & Intensive Care Medicine, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge, CB23 3RE, UK
Acute cardiogenic pulmonary oedema (ACPO) is a life-threatening consequence of acute heart failure that affects more than 17000 patients in the UK per year[i]. As the left ventricle fails, increased hydrostatic pressure causes fluid to leave the pulmonary capillaries and fill the alveoli. Clinical features of ACPO include dyspnoea, tachypnoea, wheeze, pulmonary crepitations and hypoxaemia.
If patients remain hypoxaemic despite oxygen therapy, tracheal intubation and mechanical ventilation may be required. However, the need for mechanical ventilation can be reduced by using non-invasive ventilation (NIV) delivered via facemask, either by continuous positive airway pressure (CPAP) or by non-invasive intermittent positive pressure ventilation (NIPPV). CPAP maintains a constant positive pressure throughout the cycle, whereas NIPPV increases airway pressure during inspiration. Both forms of NIV improve oxygenation, reduce work of breathing and improve cardiac output.
Systematic reviews have found that early use of NIV reduces mortality, tracheal intubation rate and intensive care unit length of stay in patients with ACPO[ii]. The largest randomised controlled trial to date found that NIV improved symptoms and physiological parameters, but did not improve mortality[iii]. As a result of these benefits, current European Society of Cardiology guidelines recommend the use of NIV in patients with ACPO. A recent survey of Coronary Care Units in England found that only 73% have the facility to provide NIV, with the majority providing CPAP rather than NIPPVi. There is still some way to go before the benefits of NIV in ACPO are fully realised in routine clinical practice.
For more information, please see Core Topics in Cardiothoracic Critical Care, edited by Andrew Klein, Alain Vuylsteke and Samer A. M. Nashef, published by Cambridge University Press.
i. Holzmann T, Moore J, Sharman M. National survey of the use of non-invasive respiratory support for acute cardiogenic pulmonary oedema in coronary care units in England. Journal of the Intensive Care Society 2010; 11: 179-181.