High Flow Nasal Oxygen and Acute Left Heart Failure

1. The anticipated number of patient subjects will reach 120 in the study. The patient's condition should be informed to his/her next of kin and then agree to signs the informed consent.

2. When passing spontaneous breathing trials and removing tracheal tube, the patients should be divided into two groups by random digital table.

3. Group A/HFNO group: the patients should receive the treatment of high flow nasal oxygen immediately after extubation. The initial flow speed was set at 30L/min and increased at 5L/min in titrated type until the patient feels uncomfortable. The temperature was set at 37℃. The fraction of inspiration O2 was set in accordance with specific condition of patient to insure oxygen saturation more than 95%.

Group B/NIV group: the patients should receive the treatment of non-invasive ventilation immediately after extubation. The initial pressure are set at a lower level (inspiratory pressure: 6-8cmH2O, expiratory pressure: 4cmH2O) and adjusted to a suitable level in 10-20min. The fraction of inspiration O2 was set in accordance with specific condition of patient to insure oxygen saturation more than 95%.

4. The criteria of successful extubation: the patient doesn't require re-intubation within 48 hours after extubation.

The criteria of extubation failure: the patient needs re-intubation and ventilation support within 48 hours after extubation.

5. (1) Investigators should keep a record of these patient's general condition, for instance, age, sex, diagnosis, Apache II score, treatment, etc.(2) Investigators should routinely detect clinical manifestation, ventilation parameters and physiological indices of the recruited patients. Elementary monitoring indicators consist of vital signs, oxygen saturation, ECG, tidal volume, breathing rate, inspiratory pressure, expiratory pressure and blood gas analysis. Blood gas analysis should be evaluated on an average of 12 hours, within the range of 48 hours after extubation.(3) Clinical prognosis of these patients should be recorded, including the rate of weaning failure, re-intubation rate, time for re-intubation, causes of re-intubation, duration of HFNO/HIV, length of ICU stay, hospitalization time and number of death.（4） The data of adverse effect derived from devices applied in the study should be recorded. HFNO group: dry nasal cavity, dry oropharyngeal cavity, dysphagia.HIV group: dry oropharyngeal cavity, skin injury caused by mask oppression, gaseous distention, vomiting, respiratory aspiration, air leak, drying sputum, difficulty in coughing up phlegm and claustrophobia.