Out-of-Hospital CPAP for Severe Cardiogenic Pulmonary Edema

Cardiogenic pulmonary edema (CPE) is a frequent presenting process for acute out-of-hospital practice. Acute left heart failure may occur from a variety of processes that rapidly deteriorates to this generalized cardiopulmonary disorder. The classical treatment of out-of-hospital CPE includes supplemental oxygen, vasodilators, loop diuretics, and morphine. 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. Continuous positive airway pressure (CPAP) has been proposed as an alternative to mechanical ventilation in CPE. This technique not only improves alveolar recruitment and decreases the work of breathing 4 but also reduces left ventricular afterload, and both right and left ventricular preload. The overall effect of CPAP in the acute management of CPE is to improve cardio-respiratory function and sustained tissue oxygenation. Furthermore, the combination of CPAP with medical treatment in patients with CPE significantly reduces the need for intubation and improves the outcome.

Unfortunately, very limited data are available on the effects of CPAP in the out-of-hospital practice. Thus, we tested the potential benefit of immediate use of CPAP alone in comparison with pharmacological therapy in treatment of CPE in the acute out-of-hospital environment.

The protocol lasts 45 minutes, divided into 3 periods of 15 minutes. Patients with severe pulmonary edema are randomly assigned in 2 groups: 1/ "Early CPAP" (n=63): CPAP alone (T0-T15); CPAP + medical treatment (T15-T30); medical treatment alone (T30-T45); 2/ "Late CPAP" (n=61): medical treatment alone (T0-T15); medical treatment + CPAP (T15-T30); medical treatment alone (T30-T45). Primary endpoint : effect of early CPAP on a dyspnea clinical score and on arterial blood gases. Secondary endpoints : incidence of tracheal intubation, inotropic support, and in-hospital mortality.

Inclusion criteria

• Patients with clinical symptoms of acute pulmonary edema such as orthopnea, diffuse crackles without evidence of pulmonary aspiration or infection, percutaneous oxygen saturation  90% despite supplemental oxygen therapy (15 L.min-1) provided by the first responders were included in the study.

Exclusion criteria

• patients with a history of chronic obstructive pulmonary disease, asthma, severe stenotic valvular disease, or if they had cardiovascular collapse or an impaired level of consciousness.