Prehospital continuous positive airway pressure ventilation in ACPO: Part 1

Abstract

Acute cardiogenic pulmonary oedema (ACPO) is a common medical emergency facing UK paramedics. While swift management can delay progression of ACPO, many patients spiral into deteriorating respiratory and cardiac function, leading to respiratory failure requiring endotracheal intubation (ETI). Continuous pulmonary airway pressure (CPAP) is increasingly being adopted for ACPO in the hospital setting, leading to moves to introduce it into prehospital care. This article is the first in a two part review of the literature surrounding CPAP. It presents a critique of the in–hospital studies in order to highlight implications for paramedics wishing to introduce CPAP into their practice. Methods: A comprehensive literature search of MEDLINE and CINAHL from 2000 to November 2010 was conducted using ‘CPAP’ as a subject heading combined with the sub headings: ‘Pulmonary Oedema’, ‘Pulmonary Edema’ ‘ACPO’, ‘Heart Failure’ ‘pre hospital’ and ‘Paramedic’ as key words. A second search was conducted using ‘Non invasive Ventilation’ as a subject heading along with all the subheadings above. Results: 253 papers were retrieved. These were manually scanned for relevance and eligibility, leaving 53 papers for review. In hospital studies were finally limited to 10. Application of CPAP resulted in significant improvements in physiological variables, need to ETI and relief of breathlessness. However, these benefits were not transferred into improved mortality. Maximizing medical therapy to include the use of intravenous nitrates significant improved mortality, and subsequently confounded the results of many CPAP trials. Conclusion: while application of CPAP is yet to be robustly attributed to improved survival in hospital, it may offer opportunities unique to the prehospital environment. Application of CPAP earlier in the acute phase of ACPO has the potential to improve mortality; it would offer a non–invasive means of supporting ventilation prior to ETI, and palliation of breathlessness. Prior to any such moves, consideration should be given to adherence and maximisation of current medical therapy within JRCALC, and future potential for use of intravenous nitrates.