The investigators adopt Noninvasive Positive Pressure Ventilation for weaning in tracheotomy patients innovatively. The investigators randomly allocate the subjects into two groups. One group is weaned by traditional strategy. The other one is weaned by Noninvasive Positive Pressure Ventilation by plugging the tracheotomy tube and deflating the cuff.

The investigators adopt Noninvasive Positive Pressure Ventilation for weaning in tracheotomy patients innovatively .If patients'conditions met our defined criterions, the investigators randomly allocate two groups. One group adopts traditional weaning strategy, the other adopts Noninvasive Positive Pressure Ventilation. If patients' condition deteriorated in group two, the investigators turned them to invasive positive pressure ventilation, until patients adapted in a satisfactory condition, the investigators shift them into Noninvasive Positive Pressure Ventilation. The investigators will extubate the tracheotomy tube, if patients are received Noninvasive Positive Pressure Ventilation more than 24 to 48 hours. After extubation, the investigators try to wean Noninvasive Positive Pressure Ventilation. Successful wean is defined weaning mechanical ventilation more than 48 hours.

Inclusion Criteria:

• age ≥ 18 years
• tracheotomy mechanical ventilation patients

Exclusion Criteria:

• pregnancy
• respiratory and hemodynamic instability
• Recent oral，nasal，facial or cranial trauma or surgery
• contra-indications for nasal or facial mask (facial skin lesions,...)
• recent history of upper gastro-intestinal surgery
• recent history of myocardial infarction
• unconscious patients
• non cooperative patient