In the patients with COPD mechanical ventilation, the bronchial dilatation is very common. However, the evaluation of the efficacy of the medical examination and other subjective indicators, such as doctors, depends on the doctor's experience; at present, there is no objective evaluation index. For patients with mechanical ventilation, the risk of cross infection can not only increase the risk of cross infection, but also increase the workload of clinical doctors and nurses. Therefore, this study proposes an objective evaluation method to evaluate the response of COPD patients to bronchial dilation. The hypothesis of this study can be used to guide the clinical medication through the test of the bronchus. If the patients with bronchial dilation test positive were used in the test, the patients were not used. In this evaluation method, the changes of airway resistance were measured by the accurate measurement of the patients with inhaled bronchial dilatation.

Inclusion Criteria:

• Acute exacerbation of chronic obstructive pulmonary disease
• The mechanical ventilation time of the outdoor endotracheal intubation in the intensive care unit was less than 48 hours

Exclusion Criteria:

• asthma
• has received tracheotomy
• long term mechanical ventilation (which has been accepted for more than 21 days).
• severe pneumonia
• Patients who cannot use a patient with bronchial dilation
• there's a taboo on the use of a sedative.
• refusal to participate in the study
• 48 hours to pull out the tube