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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
SUPPORTIVE_CARE
Masking
NONE
Enrollment
20
After a 'baseline' trial using Venturi Mask, within the first 120 minutes after extubation, and assessing a PaO2/FiO2 ratio \< 300, patients will be randomly assigned to a first 1h-phase of 'conventional HFNO' or 'DUET HFNO'. At the end of each session several clinical parameters (i.e. DUS, EIT, ABGs, comfort, VAS) will be collected. Specifically, Gas-flow rate will be set at a maximum of 60 L/min, temperature at a maximum of 37°C, while FiO2 will be adjusted to maintain SpO2 between 92 and 98%.
After a 'baseline' trial using Venturi Mask, within the first 120 minutes after extubation, and assessing a PaO2/FiO2 ratio \< 300, patients will be randomly assigned to a first 1h-phase of 'DUET HFNO' vs 'conventional HFNO'. At the end of each session several clinical parameters (i.e. DUS, EIT, ABGs, comfort, VAS) will be collected. Specifically, Gas-flow rate will be set at a maximum of 60 L/min, temperature at a maximum of 37°C, while FiO2 will be adjusted to maintain SpO2 between 92 and 98%. A 5-10min 'washout' phase using VM, between different interfaces, will be allowed.
Institute of Anaesthesia and Intensive Care, Padua University hospital
Padova, Italy
Breathing effort
To evaluate changes, between arms, in breathing effort (as assessed by diaphragm ultrasound (DUS)).
Time frame: Last 10 minutes of 1 hour-trial
Lung aeration
To evaluate changes, between arms, in lung aeration (as assessed by the end-expiratory lung impedance (delta EELI) through EIT.
Time frame: Last 10 minutes of 1 hour-trial
Minute ventilation (MV) (L/min)
To evaluate breathing pattern
Time frame: Last 10 minutes of 1 hour-trial
corrected MV (L/min)
To evaluate breathing pattern
Time frame: Last 10 minutes of 1 hour-trial
Breathing heterogeneity
To evaluate changes, between arms, in ventilation distribution (as assessed by pendelluft (yes/not), respiratory rates/min, tidal volume (ml), global inhomogeneity index through EIT)
Time frame: Last 10 minutes of 1 hour-trial
Comfort
To evaluate changes in comfort, between arms, as assessed by NRS scale
Time frame: Last 10 minutes of 1h-trial
Dyspnea
To evaluate changes in dyspnea, between arms, as assessed by VAS scale
Time frame: Last 10 minutes of 1h-trial
Gas exchange
To evaluate changes, between arms, in gas exchange (as assessed by PaO2 mmHg, pCO2 mmHg, pH through ABGs)
Time frame: Last 10 minutes of 1h-trial
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