RENOVATE Palliative: HFNC vs. Standard Respiratory Support in Patients With Do-Not-Intubate Order and ARF

Experimental intervention (HFNC) The HFNC (AIRVO 2 - Fisher \& Paykel Healthcare, Auckland, New Zealand) consists of a device that allows FiO2 adjustable from 21 to 100% and that delivers a flow of humidified and heated gas up to 60 l / min and 37 degrees C of temperature. The HFNC will be offered until resolution of the ARF or until decision by the assisting team and the patient and/or their legal guardian, for the suspension of the treatment due to intolerance, and/or worsening of the discomfort and / or dyspnea. The HFNC should be offered to the patient in ARF as follows: * Initial parameters: Flow 45 ml / L, FiO2 50%, AIRVO 37oC temperature; * Titrate the flow up to 60ml / L or up to the maximum tolerated; * Titrate FiO2 to maintain SatO2 between 92% to 98%, starting with 50%; * Keep the AIRVO temperature at 37oC, if not possible, acceptable down to 34oC.

The patient randomized to standard respiratory support will be placed on conventional low flow oxygen therapy according to the center's standard of care aiming at SpO2 90 - 98% and improvement of dyspnea. For cases refractory to oxygen therapy, keeping SpO2 below 90% or if dyspnea does not improve, non-invasive positive pressure ventilation (NIPPV) may be offered at the discretion of the assistant team. NIPPV will be performed with the patient in a supine position at 45 degrees. The mask will be facial (oronasal or full face) with an appropriate size for each patient and adapted in a way to minimize leakage. A hydrocolloid dressing can be placed over the nose in order to avoid ulcerations and increase comfort. The NIPPV will be performed with the help of a ventilator with inspiratory and expiratory circuits or with Bilevel devices with a single circuit and exhalation valve according to the availability of each center.