The Efficacy of the Whisperflow CPAP System Versus Nasal High Flow in Patients at High Risk for Postextubation Failure
The Efficacy of the Whisperflow CPAP System Versus Nasal High Flow in Patients at High Risk for Postextubation Failure
The purpose of this study is to compare the effect of continuous positive airway pressure
 (CPAP) delivered by the variable generator WhisperFlow System with high flow nasal cannula
 oxygen therapy in mechanically ventilated patient who are at risk for postextubation failure.
Postextubation respiratory failure is not an uncommon condition after discontinuation of
 mechanical ventilation. Subsequently reintubation and mechanical ventilation for
 postextubation respiratory failure may lead to increasing of hospital morbidity and mortality
 and and prolonging intensive care and hospital stay. Several studies have demonstrated the
 efficacy of non-invasive ventilation to prevent the postextubation failure in patients with
 high risk for extubation failure.

 The variable generator whisper flow system ((Philips Respironics, Murrysville, PA, USA) is
 the one of widely used continuous positive airway pressure(CPAP) device in UK. This device
 employs an oxygen-driven venturi to entrain air and generates high fresh gas flow up to 140
 liter per minute. The oxygen/air mixture enters the breathing circuit and exits through a
 threshold resistor namely CPAP valve. Whisperflow is able to provide the flow into the
 breathing system via oronasal mask which exceeds the peak inspiratory flow rate of the
 patient and may improve work of breathing as well as gas exchange. In daily clinical
 practice, the investigators apply this device with humidifier in patients with weaning
 difficulty and patients who are at risk for postextubation failure.

 High-flow nasal oxygen therapy(HFNO) is a device which heated and humidified oxygen is
 distributed to the nose at high flow rates. With the high flow rate (up to 60 Liter per
 minute), it generates low level of positive airway pressure. Physiological benefits of HFNO
 comprises decreasing of the dead space, work of breathing and the low level of positive
 airway pressure associated with better lung recruitment. Furthermore, the fraction of
 inspired oxygen can be adjusted and measured by changing the fraction of oxygen in the
 driving gas.

 In the present randomized, controlled trial, the investigators will compare two devices for
 oxygen therapy, with low levels of continuous positive airway pressure, nasal high-flow
 oxygen therapy and CPAP of 5 cmH2O delivered by the variable generator WhisperFlow System
 with oronasal mask , in critically ill patients who are at risk for postextubation failure.
 The investigators hypothesize that nasal high-flow is superior to CPAP the in terms of
 reintubation rate.
Inclusion Criteria:

 -  Mechanical ventilation > 48 hours and

 -  high risk for extubation failure namely , congestive heart failure, ineffective cough
 and excessive tracheobronchial secretions, more than one failure of a weaning trial,
 more than one co-morbid condition, patients who had hypercapnia, and upper airway
 obstruction without immediately required intubation

 Exclusion Criteria:

 -  age<18 years

 -  pregnancy

 -  tracheostomy

 -  uncontrolled cardiac ischemia or arrhythmias

 -  unstable hemodynamic status

 -  documented swallowing problem

 -  documented cervical spine injury

 -  Facial anatomical abnormalities interfering with the mask fit

 -  agitated or uncooperative state

 -  lack of informed consent