• Treatment success after the one hour study period, defined as all of respiratory rate less than 25 bpm, oxygen saturation greater than 90 %.
  

• Physiological parameters: vital signs, dyspnea , intubation rate
  
• Safety parameters: adverse events , duration of hospitalisation , mortality 5 days and 30 days after the end of the one hour study period.
  

Acute cardiogenic pulmonary edema is a frequent medical emergency. Several studies have shown that continuous positive airway pressure is effective in acute cardiogenic pulmonary edema, through improvement in gas exchange, reduction in intubation rate and a trend towards reduced mortality. CPAP is usually obtained with a hermetic nasal or facemask witch has an expiratory valve to maintain a positive pressure at the end of the expiration. With this support, the patient does not receive any assistance with respiration.

The available data about CPAP concern patients hospitalised in cardiology intensive care units, in resuscitation areas or in emergency departments.

We will undertake a controlled prospective randomised trial to investigate whether the early use of CPAP would improve oxygenation and survival, as compared with standard medical therapy in patients with acute cardiogenic pulmonary edema.

This study will include 124 patients over 18 years of age, suffering of acute cardiogenic pulmonary edema, with a respiratory rate greater than 25 bpm and oxygen saturation less than 90 %. The patients will be include just after the beginning of the episode, in prehospital mobile intensive car unit (SAMU) and will be all admitted in resuscitation area in a central hospital. They will be randomly assigned to CPAP or conventional oxygen therapy. The randomisation sequence is generated by the random numbers table. Closed envelopes containing the allocated treatment will be stored in the emergency department and will be opened when the patient is included.

Oxygen saturation (by pulse-oxymetry), heart rate, respiratory rate, dyspnea, blood pressure will be measured every 15 min during the transport to the intensive care unit and every hour. The blood gazes will be measured at the arrival. The intubation rate, the duration of the hospitalisation and the mortality in the thirty days following initial treatment will be noted.