Patients are included at home after informed consent by the emergency medical team and transported during the following 2 hours to a cardiac intensive care unit were the treatment is purchased as well. Randomization process has been done previously with envelopes ; group A : pharmaceutical treatment alone , B pharmaceutical plus CPAP. Medical treatment includes furosemide and nitroglycerin (continuous perfusion and bolus), inotropes if needed, and all other specific treatment required (ex : anti antiarrhythmic drugs). Doses are free, adapted to the clinical response for respiratory and hemodynamic distress. CPAP is a passive high flow venturi system device alimented by a hyperbaric oxygen. FiO2 can be controlled and adapted to the pulsed oxygen saturation. PEP must be initially celled at least at 7.5 cmH2O and increased to 10 if well tolerated.