How to read the report of lung function relaxation test

The report of lung function relaxation test mainly examines five aspects: basic lung function indicators, numerical changes before and after bronchial relaxation, positive judgment criteria, clinical significance, and precautions.

1. Basic indicators: The first item of the

report usually displays basic lung function data, including forced vital capacity, first second forced expiratory volume, maximum mid expiratory flow rate, etc. These values reflect the initial degree of airway patency of the tester, and the baseline values for patients with chronic obstructive pulmonary disease are often 80% lower than the predicted values. A preliminary judgment needs to be made based on the normal reference range on the right side of the report.

2. Numerical comparison:

focuses on the rate of change in indicators before and after the use of bronchodilators. The key comparison is the improvement rate of forced expiratory volume in the first second, calculated using the formula of post medication value - pre medication value/pre medication value x 100%. Some reports will directly indicate the percentage change, which is clinically significant if the value exceeds 12% and the absolute value increases by more than 200 milliliters.

3. Positive criteria:

Positive results indicate the presence of reversible airway obstruction, commonly seen in bronchial asthma. Two conditions must be met: the improvement rate of forced expiratory volume in the first second is ≥ 12%, and the absolute value increases by ≥ 200 milliliters. Some institutions use a forced lung capacity improvement rate of ≥ 12% as an auxiliary judgment criterion, but the specificity is low.

4. Clinical interpretation:

positive results are commonly seen in asthma, chronic obstructive pulmonary disease with airway hyperresponsiveness. A negative result may indicate irreversible airway disease or the use of bronchodilators prior to testing. Based on medical history, false negatives may occur in cough variant asthma, while false positives may occur in patients with severe emphysema.

5. Precautions: Before

testing, bronchodilators should be discontinued, short acting β 2 receptor agonists should be discontinued for 6 hours, and long-acting preparations should be discontinued for 12 hours. During the testing process, it is necessary to cooperate with technical personnel to complete three qualified exhalation movements, with a variation rate of less than 5%. The report form needs to be saved for follow-up comparison, and dynamic observation of changes is more valuable than a single result. After receiving the report, it is recommended to bring it to the respiratory clinic for interpretation. The doctor will conduct a comprehensive evaluation based on clinical symptoms. Smoking and exposure to secondhand smoke should be avoided in daily life, and outdoor activities should be reduced when the air quality is poor. Asthma patients can record daily peak expiratory flow rate, and patients with chronic obstructive pulmonary disease are recommended to undergo respiratory rehabilitation training. Regular follow-up of lung function can effectively monitor disease progression, and treatment plans need to be adjusted in a timely manner during acute exacerbations. Pay attention to keeping warm and preventing colds in winter, and vaccination can reduce the risk of respiratory infections.