A Randomised Controlled Trial of High-Flow Nasal Oxygen Versus Standard Oxygen Therapy in Critically Ill Immunocompromised Patients

Acute respiratory failure (ARF) is the leading reason for ICU admission in immunocompromised patients. Usual oxygen therapy involves administering low-to-medium oxygen flows through a nasal cannula or mask \[with or without a bag and with or without the Venturi system\] to achieve SpO2≥95%. Oxygen therapy may be combined with non-invasive ventilation \[NIV\] providing both end-expiratory positive pressure and pressure support. However, in a recent trial by our group, non-invasive ventialtion \[NIV\] was not superior over oxygen without NIV. High-flow nasal oxygen \[HFNO\] therapy is a focus of growing attention as an alternative to standard oxygen therapy. By providing warmed and humidified gas, HFNO allows the delivery of higher flow rates \[of up to 60 L/min\] via nasal cannula devices, with Fraction of inspired oxygen (FiO2) values of nearly 100%. Physiological benefits of HFNO consist of higher and constant FiO2 values, decreased work of breathing, nasopharyngeal washout leading to improved breathing-effort efficiency, and higher positive airway pressures associated with better lung recruitment. Clinical consequences of these physiological benefits include alleviation of dyspnoea and discomfort, decreases in tachypnoea and signs of respiratory distress, a diminished need for intubation in patients with severe hypoxemia, and decreased mortality in unselected patients with acute hypoxemic respiratory failure However, although preliminary data establish the feasibility and safety of this technique, HFNO has never been properly evaluated in immunocompromised patients. Thus, this project aims at demonstrating that HFNO is superior to low/medium-flow (standard) oxygen, minimising day-28 mortality