This study is designed to determine whether the optimized inhalation therapy based on peak inspiratory flow rates (PIFR) measured against the simulated resistance can reduce the rate of treatment failure in patients recovering from acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Errors in inhaler use and quality of life are also to be evaluated.

The study will recruit 460 patients with AECOPD whose exacerbated symptoms are relieved by 5-7 days of standard therapy. The participants are divided into PIFR group and control group in a 1:1 ratio according to a random number table method. All the patients will be given inhaled corticosteroid（ICS）/long-acting β agonist（LABA） (budesonide/ formoterolSymbicort turbuhaler® 160/4.5 μg bid or Beclometasone/ Formoterol Foster® pressure metered dose inhaler(pMDI) 100/6 μg 2 puff bid). For symptomatic patients before acute exacerbation, Spiriva handihaler® 18μg qd or Spiriva respimat® 2.5μg qd will be prescribed in combination with ICS/LABA. For PIFR group, PIFR is measured by InCheck DIAL(Clement Clarke International Ltd, Harlow, UK and Alliance Tech Medical). If PIFR is less than 60L/min , the patient will be given pMDI with spacer. If PIFR value is over 60 L/min, the patient will be given dry powder inhaler(DPI).). The control group will be given DPI or pMDI with spacer according to the judgment of a respiratory physician. Both groups will be taught to use the device after the prescription, and then be reminded to use medication via a WeChat public account.

The primary endpoint of the study is the 30-day treatment failure including AECOPD recurrence resulting in an emergency visit, admission, or need for intensified medication). The secondary endpoints of the study are the error rate of inhalation device use, satisfaction with inhalation devices, symptoms and quality of life, 30-day mortality, chronic obstructive pulmonary diseases(COPD)-related treatment costs and PIFR.

Inclusion Criteria:

• Patients with acute exacerbation of chronic obstructive pulmonary disease(AECOPD) whose acute respiratory symptoms have been controlled after 5-7 day-standard AECOPD treatment including atomized or inhaled brochodilator plus oral or intravenous glucocorticoid (prednisone equivalent dose 40-50mg) or Pulmicort 2mg atomization Bid plus broad-spectrum antibiotics.
• Patients with moderate and above chronic obstructive pulmonary disease diagnosed by spirometry, ie, forced expiratory volume in one second(FEV1)/forced vital capacity(FVC) <70% post-bronchodilator and FEV1% predicted value <80%.
• Patients have signed an informed consent form.

Exclusion Criteria:

• Patients who is already using home nebulization therapy because of the severity of the illness.
• Patients with bronchial asthma, pulmonary interstitial fibrosis, bronchiectasis, pulmonary embolism and other lung diseases; or hypertension, heart disease, chronic liver and kidney disease, diabetes, chronic gastrointestinal diseases, malignant tumors, critically ill patients.
• Patient's mental state cannot match the observation or suffer from cognitive impairment.
• Patient's peak inspiratory flow rates (PIFR) is less than 20L/min.