Inclusion Criteria:  Tracheotomy and invasive mechanical ventilation is expected to be required for > 48h; When support pressure ≤ 15 cmH2O, it can withstand pressure support ventilation (PSV) time > 1h;  Exclusion Criteria:  Age < 18 years or > 85 years; Deep sedation. Severe hemodynamic instability (norepinephrine or equivalent converted dose of other vasoactive drugs > 1ug / kg.min or map ≤ 65mmhg) Severe respiratory center depression, high paraplegia, neuromuscular disease; Esophageal obstruction, esophageal perforation, severe esophageal variceal bleeding, upper gastrointestinal surgery, diaphragmatic hernia and thoracic deformity; Patients with chronic respiratory diseases requiring long-term home oxygen therapy; Patients with severe coagulation dysfunction (INR > 1.5, APTT > 44s, history of leukemia); Severe other organ dysfunction is expected to die in a short time (7 days) or palliative treatment. The estimated survival time of advanced solid organ or hematological system tumors is < 30 days Participate in other clinical studies within 30 days; Failing to sign the informed consent form;