The purpose of this study is to compare non invasive ventilation to high flow nasal cannula oxygen for the management of patients admitted with an acute respiratory failure due to an acute cardiogenic pulmonary edema.

Acute cardiogenic pulmonary oedema is a leading cause of acute respiratory distress in patients admitted in an Emergency Department. With diuretics and nitrite derivative, noninvasive ventilation is the first-line treatment of acute pulmonary oedema recommended by the European Society of Cardiology. Noninvasive ventilation is able to reduce the respiratory rate faster than standard oxygen therapy, to improve oxygenation, and some data suggest it could reduce the mortality rate. NIV may be poorly tolerated in certain patients, in whom it is associated with failure of treatment and poor outcomes. High-flow nasal cannula heated and humidified oxygen (HFNO) is a ventilatory support used in ICU and recently introduced in Emergency Departments. As compared NIV and standard oxygen therapy, HFNO reduces the mortality rate in patients with acute hypoxemic respiratory failure hospitalized in an ICU. In addition, in these patients, HFNO is also better tolerated than noninvasive ventilation. Some data suggested HFNO is superior to standard oxygen therapy in acute pulmonary oedema and could have a similar clinical effect to NIV. However, there is no research that has compared tolerance of patients admitted in an ED with acute pulmonary oedema and treated by HFNO or NIV.

Included patients will be treated with NIV or HFNO. NIV will be provided with an emergency and transport ventilator (Monnal T60, Airliquide, Antony, France) and HFNO will be provided with an AirVO2 device (Fisher and Paykel, New Zealand). Patients will be treated in an Emergency Department immediately after their admission and their consent. Treatment will be provided for a minimum of one hour. Tolerance of patients will be measured under treatment using a comfort numerical scale from 0 - well comfortable to 10 extremely uncomfortable. Clinical and biological patterns will be also recorded. Patients will be followed from their inclusion to 28 days after their inclusion.

Inclusion Criteria:

• age over or equal 18 years old
• admitted in an Emergency Department
• acute respiratory failure defined by a respiratory rate over or equal 25 breathes/min or signs of increased work of breathing
• clinical suspicion of acute heart failure defined bu the European Cardiologic Society.

Exclusion Criteria:

• patient requiring immediate invasive mechanical ventilation
• neurologic distress defined by a Glasgow Coma Scale under 13
• haemodynamic failure defined by a Mean Blood Pressure under 65 mmHg or patient requiring catecholamines