'Optiflow + Duet' Interface' vs 'Standard' High Flow Nasal Cannula

Physiological Effects of High Flow Oxygen Therapy Using 'Optiflow + Duet' Interface vs 'Standard' High Flow Nasal Cannula for Acute Respiratory Failure After Extubation. The OPTIMARF Study.

High-flow nasal cannula (HFNC) therapy is increasingly used in the management of acute respiratory failure. Its clinical application has been largely investigated in chronic obstructive pulmonary disease (COPD) patients but only marginally in patients experiencing acute respiratory failure after extubation. Promising data have been published in vitro about new asymmetrical high flow nasal cannula, named 'Optiflow + DUET'. Positive airway pressure, that dynamically changes with breathing, and clearance of anatomical dead space are the key mechanisms of noninvasive respiratory support with nasal high flow. Pressure mainly depends on flow rate and nare occlusion. The hypothesis is that an increase in asymmetrical occlusion of the nares leads to an improvement in dead-space clearance resulting in a reduction in re-breathing and breathing work.

A prospective cross-over RCT on the effects of 'Optiflow + DUET' as compared to convetional symmetrical high flow cannula and Venturi mask.

Inclusion Criteria:

• age >18 years old;
• invasive mechanical ventilation > 24h;
• acute respiratory failure within 120 minutes after extubation (defined during a spontaneous trial using Venturi mask and assessing a PaO2/FiO2 ratio < 300;
• absence of Sars-Cov-2 positivity;
• absence of cardiological or long-term respiratory disease

Exclusion Criteria:

• pregnancy
• tracheostomy
• non-invasive ventilation after extubation
• second tracheal intubation
• contraindications for EIT belt
• facial or nose abnormalities