To Assess the Utility of Impulse Oscillometry on a Differential Diagnosis among the Patients with ACOS,asthma and COPD over Age 40.

ACOS,asthma and COPD are prevalent diseases with similar manifestations and different type airway impairments. The differential diagnosis is not easy because the patients always complain of the similar symptoms and are not able to complete spirometry well.

Impulse Oscillometry System (IOS) is capable of identifying airway obstruction and reactions to bronchodilators by providing impedance data and curves. IOS is also a patient-friendly and valuable tool with minimal demands on patient and requiring only passive cooperation.

IOS is a tool to measure lung function during tidal breathing. The output is a measure of respiratory impedance (Zrs), which include the respiratory resistance (Rrs) and respiratory reactance (Xrs) measured over a range of frequencies (usually from 3 to 35 Hz).

The main objective of this study is to investigate the ability of IOS to measure small airway disease by providing different impedance profiles for participants with ACOS,asthma and COPD. Another objective of this study is to investigate the differential ability to identify three diseases by measuring airway impedance and reactions to bronchodilators.

First,participants completed the IOS test.Second,participants inhaled salbutamol for 200g 15 minutes to repeat the IOS.The investigators collect these 2 data for analysis.

Inclusion Criteria:

- 1.1 ACOS:

1. Patient is older than 40 years old.
2. There are characteristics of bronchial asthma and COPD.
3. There is a history of exposure to risk factors.
4. Existence of persistent airflow limitation: After the application of bronchodilators, FEV1/FVC<0.7, and lung function proved reversible exhalation.
5. The existence of reversible airflow limitation: Bronchial Dilation Test positive.

1.2Asthma: 1)Patient is older than 40 years old. 2)History of reversible respiratory symptoms. 3) non-smokers. 4)lung function:At least one time proved that the airflow limitation: Bronchial Dilation Test positive.

5)previously diagnosed asthma. 1.3COPD:

1. Patient is older than 40 years old.
2. Complaints about dyspnea, chronic cough or expectoration.
3. There is a history of exposure to risk factors.
4. Existence of persistent airflow limitation: After the application of bronchodilators, FEV1/FVC<0.7.
5. The existence of irreversible airflow limitation: Bronchial Dilation Test negative.

Exclusion Criteria:

- 2.1 Combining other respiratory diseases that affect airflow,such as lung cancer, tuberculosis, pneumonia and bronchiectasis.

2.2 At the time doing lung function test, the factors that affect the airflow limitation are not stopped or just stopped with the time interval not long enough to meet the test standard.

2.3 Using special accompanying medication. For example, patients with drugs such as glucocorticoid.

1. Patients that meet one of the diganosis:ACOS,Asthma and COPD.
2. Without factors in exclusion criteria.
3. Over 40 years old.