Title: Support ventilation versus conventional oxygen
Abstract: Although the population size in Josep Masip and colleagues’ study1Masip J Betbesé AJ Páez J et al.Non-invasive pressure support ventilation versus conventional oxygen therapy in acute cardiogenic pulmonary oedema: a randomised trial.Lancet. 2000; 356: 2126-2132Summary Full Text Full Text PDF PubMed Scopus (359) Google Scholar was small, they were able to show a more rapid recovery and a lower likelihood of endotracheal intubation with noninvasive pressure support ventilation than with conventional oxygen therapy. We did a similar trial of continuous positive airways pressure (CPAP) in 58 patients (mean age 78 years, 26 men) admitted to our institution with acute cardiogenic pulmonary oedema. All patients received standard intravenous opiate, nitrate, and diuretic therapy and were randomly assigned CPAP or conventional oxygen therapy. Patients’ baseline characteristics were well matched in the two groups. Patients receiving CPAP therapy reported a significantly better improvement in symptoms, coincident with a greater reduction in respiratory rate, heart rate, and acidosis at 1 h, than did those receiving conventional oxygen therapy. These differences were not sustained at 6 h. The length of stay in high-dependency areas, endotracheal intubation rate, and the total duration of hostital stay were similar for the two groups. The overall hospital mortality in patients treated with CPAP was also lower than that for patients receiving conventional treatment. When we compare our findings with previous CPAP trials (table), the pooled data suggest that CPAP therapy confers an overall survival benefit in patients who have acute pulmonary oedema, with a relative risk reduction of 0·5 (95% CI 0·30–0·84).TableEffect of CPAP on predischarge hospital mortality: pooled dataConventional oxygen therapyCPAPDiedTotalDiedTotalRäsänen et al. 19852Rasanen J Heikkla J Downs J Nikki P Vaisanen I Viitanen A Continuous positive airway pressure by face mask in acute cardiogenic pulmonary edema.Am J Cardiol. 1985; 55: 296-300Summary Full Text PDF PubMed Scopus (306) Google Scholar620320Bersten et al, 19913Bersten AD Holt AW Vedig AE Skowronski GA Baggoley CJ Treatment of severe cardiogenic pulmonary edema with continuous positive airway pressure delivered by face mask.N Engl J Med. 1991; 325: 1825-1830Crossref PubMed Scopus (531) Google Scholar420219Lin et al, 19954Lin M Yang YF Chiang HT Chang MS Chiang BN Cheitlin MD Reappraisal of continuous positive air-way pressure therapy in acute cardiogenic pulmonary edema: short-term results and long-term follow-up.Chest. 1995; 107: 1379-1386Crossref PubMed Scopus (283) Google Scholar650450Edinburgh study731227Pooled data*p<0·01, χ2 test for conventional oxygen therapy versus CPAP.2312111116* p<0·01, χ2 test for conventional oxygen therapy versus CPAP. Open table in a new tab There have been many small-scale trials of CPAP, BiPAP,5Mehta S Jay GD Woolard RH et al.Randomized, prospective trial of bilevel versus continuous positive airway pressure in acute oulmonary edema.Crit Care Med. 1997; 25: 620-628Crossref PubMed Scopus (417) Google Scholar and now non-invasive pressure support ventilation, for acute pulmonary oedema. No trial has been of sufficient power to be definitive, but all studies report conistent findings and the pooled data we present are encouraging. There is an urgent need for a multicentre randomised controlled trial of positive airway pressure support compared with conventional oxygen therapy. Whether specific modes of pressure support are better than others would, as Masip and colleagues suggest, require a much larger trial, but this issue is perhaps subsiduary to the main question of whether all patients presenting with acute cardiogenic pulmonary oedema should be considered for positive airway pressure support because of potential morbidity and mortality benefits.