Continuous positive airway pressure for cardiogenic pulmonary edema: a randomized study

Abstract

Study Objective

The purpose of this randomized controlled trial was to determine the immediate and delayed effects of noninvasive ventilation for patients in acute cardiogenic pulmonary edema (ACPE) in addition to aggressive usual care in a medical prehospital setting.

Methods

Out-of-hospital patients in severe ACPE were eligible for the study. Patients were randomized to receive either usual care, including conventional optimal treatment with furosemide, oxygen, and high-dose boluses of isosorbide dinitrate plus oxygen, or conventional medications plus out-of-hospital continuous positive airway pressure (CPAP). The primary outcome was the treatment success defined as all of respiratory rate less than 25 breaths per minute and oxygen saturation of greater than 90% at the end of 1-hour study. Secondary end points included death during 30 days after inclusion. Lengths of intensive care unit and hospital stays were also recorded.

Results

In total, 124 patients were enrolled into the study. The 2 groups had similar baseline characteristics. For the primary outcome analysis, 22 (35.5%) of 62 patients were considered as experiencing a treatment success in the usual care group vs 19 (31.7%) of 60 in the CPAP group (P = .65). Seven patients died within 30 days in the usual care group vs 6 in the CPAP group (P = .52). There were no statistically significant differences between the treatment groups for length of stay either in hospital or in the intensive care unit.

Conclusion

In the prehospital setting, in spite of its potential advantages for patients in ACPE, CPAP may not be preferred to a strict optimal intravenous treatment.

Introduction

Acute cardiogenic pulmonary edema (ACPE) is a frequent presenting disease for acute out-of-hospital practice. Acute left ventricular failure may occur from a variety of processes that rapidly deteriorates to this generalized cardiopulmonary disorder. The classical treatment of out-of-hospital ACPE includes supplemental oxygen, vasodilators, and loop diuretics. If not effective or because of the associated respiratory depression, tracheal intubation and mechanical ventilation are often needed, which, by themselves are associated with a worse prognosis [1]. Bilevel positive airway pressure (BiPAP) and continuous positive airway pressure (CPAP) has been proposed to avoid mechanical ventilation in severe ACPE [2], [3], [4], [5], [6]. The overall effect of CPAP in the acute management of ACPE is to improve cardiorespiratory function and sustained tissue oxygenation. This technique not only decreases intrapulmonary shunt [6] and work of breathing [7] but also reduces left ventricular afterload and both right and left ventricular preload [8]. Collectively, the available data suggest that CPAP is effective in reduction in intubation rate and that there is a trend toward reduced mortality in emergency departments [9]. Some randomized prospective trials [10], [11], [12] have demonstrated significant improvements in vital signs and gas exchange as well as drastic reductions in intubation rates attributable to the use of CPAP. In patients with ACPE, with no effect on short-term mortality. However, the evidence for CPAP in the out-of-hospital setting is limited only to several case series, nonrandomized studies, and few randomized studies [13], [14], [15], [16], [17], [18], [19], [20], [21]. One randomized study focused on severe respiratory distress with paramedic-staffed ambulances [20], and another study focused on immediate effects on early vs late CPAP in a prehospital setting with physician-staffed ambulances [21]. To our knowledge, no study focused on ACPE in a prehospital setting compared CPAP to a placebo treatment, and no study was focused on delayed effects of CPAP vs usual care for ACPE (eg, later than in-hospital death). The purpose of this study was then to determine whether out-of-hospital treatment with CPAP improves significantly respiratory distress for patients in ACPE.