The Acute Respiratory Intervention StudiEs in Africa (ARISE-AFRICA) Study

Inclusion Criteria: * De novo acute respiratory distress, as defined by dyspnea, use of accessory respiratory muscles, and a respiratory rate of 25 breaths per minute or more, * Hypoxemia, as defined by a ratio of the partial pressure of arterial oxygen (PaO2) to the fraction of inspired oxygen (FiO2) of less than 300 mm Hg or a oxygen saturation by pulse oximetry SpO2/FiO2 ratio \<315 will be considered for inclusion * Informed consent obtained in accordance with local regulations; Exclusion Criteria: * Exacerbation of asthma, chronic obstructive pulmonary disease or another known or suspected chronic respiratory disease; * Absolute contraindications to CPAP or HFNC * Cardiac arrest; severe ventricular arrhythmia; shock defined by the need for vasopressors (dopamine \> 5 microg/kg/min or adrenaline or noradrenaline at any dose) * Altered consciousness (Coma Glasgow Score below 12 points); * Do not intubate order, do not resuscitate order, or decision to limit full care taken before obtaining informed consent; * Refusal to participate, prior enrolment in the trial, participation in another interventional study on respiratory distress;