The optimal noninvasive management of acute hypoxemic respiratory failure is debated. Helmet noninvasive ventilation may be more effective than facemask noninvasive ventilation for these patients. Putatitve benefits of helmet use are the possibility to apply significantly higher positive end-expiratory pressure without air leaks and with good patient's comfort. In this randomized crossover study, the investigators will assess the physiological effects of helmet compared to facemask noninvasive ventilation, with the latter applied with different ventilator settings (similar to or different from helmet settings).
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
20
noninvasive ventilation
Fondazione Policlinico Universitaro A. Gemelli IRCCS
Rome, Italy
Inspiratory effort
negative deflection in esophageal pressure
Time frame: 1 hour
End-expiratory lung impedance
Electrical-impedance derived end-expiratory lung volume
Time frame: 1 hour
Tidal volume
Electrical-impedance derived tidal volume size
Time frame: 1 hour
Work of breathing
Esophageal pressure simplified pressure-time product
Time frame: 1 hour
Respiratory rate
Respiratory rate per minute
Time frame: 1 hour
Dynamic transpulmonary driving pressure
Tidal change in transpulmonary pressure
Time frame: 1 hour
Compliance
Ratio of tidal volume to transpulmonary driving pressure
Time frame: 1 hour
Dyspnea
Dyspnea rated through a visual analog scale (ranging from 0 to 10, with representing most severe dyspnea) adapted for critically ill patients
Time frame: 1 hour
Discomfort
Device-related discomfort (ranging from 0 to 10, with representing most severe dyspnea) rated through a visual analog scale adapted for critically ill patients
Time frame: 1 hour
Oxygenation
PaO2/FiO2 ratio
Time frame: 1 hour
Pendelluft extent
Pendelluft extent, expressed in % of the total tidal volume
Time frame: 1 hour
Corrected minute ventilation
The product of tidal volume and respiratory rate, normalized to PaCO2. This value is expressed in Arbitrary units per minute divided by mmHg and is a proxy of dead space
Time frame: 1 hour
Arteria Carbon dioxide tension
PaCO2
Time frame: 1 hour
Tidal volume distribution
Tidal volume distribution, assessed with electrical impedance tomography in 4 regions of interest (ventral, mid-ventral, mid-dorsal, dorsal)
Time frame: 1 hour
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