Diagnosis of COPD

Once the disease occurs, COPD will seriously affect the patient's physical health, making it impossible for the patient to live and work normally. The patient may even feel that he or she often has symptoms of difficulty breathing, which is very uncomfortable. Therefore, COPD needs to be diagnosed as soon as possible so that it can be treated early and will not delay the treatment opportunity.

How to diagnose COPD

Pulmonary function tests are objective indicators for judging airflow limitation with good repeatability. They are of great significance for the diagnosis, severity evaluation, disease progression, prognosis and treatment response of acute exacerbation of COPD. Pulmonary function tests are the gold standard for diagnosing acute exacerbation of COPD.

The pulmonary function indicators for diagnosing acute exacerbation of COPD are: after using bronchodilators, FEV1 < 80% of the predicted value and FEV1/FVC < 70%, which can be determined as incompletely reversible airflow limitation. In addition to detecting FVC, spirometry can also be used to measure the content of lung gas in different inhalation or breathing states, such as vital capacity (VC), tidal volume (VT), etc.

1. FEV1 (forced expiratory volume in one second)

It is a test in which the patient takes a deep breath and then exhales as forcefully as possible, and the volume of gas exhaled in the first second is measured.

2. FVC (Forced Vital Capacity) is also called Forced Expiratory Capacity

It refers to the maximum volume of gas that can be exhaled by inhaling to the total lung volume and then exhaling to the residual volume with the greatest force and fastest speed.

3.VC (vital capacity) is also called slow vital capacity (SVC)

It refers to the maximum expiratory volume that can be achieved by slow, unforced breathing after a deep, forced inspiration to the total lung capacity. In patients with acute exacerbations of COPD, VC is often greater than FVC because of premature airway collapse and occlusion during forced expiration.

COPD should be differentiated from bronchial asthma, bronchiectasis, congestive heart failure, pulmonary tuberculosis, bronchial lung cancer, and bronchiolitis obliterans. It is sometimes difficult to differentiate it from bronchial asthma. COPD usually develops after middle age, while asthma usually develops in childhood or adolescence. The symptoms of COPD progress slowly and gradually worsen, while the symptoms of asthma fluctuate greatly. Patients with COPD often have a history of long-term smoking and/or exposure to harmful gases and toxic particles. Asthma is often accompanied by specific constitution, allergic rhinitis and/or eczema, and some patients have a family history of asthma.

The airflow limitation in COPD is basically irreversible, while that in asthma is mostly reversible. However, for some patients with long-term asthma who have already undergone airway remodeling, the airflow limitation cannot be completely reversed; while for a small number of patients with COPD and airway hyperresponsiveness, their airflow limitation may be partially reversible. At this time, a comprehensive analysis should be conducted based on clinical and laboratory examinations, and if necessary, bronchial provocation tests, bronchial dilation tests and (or) diurnal variation of maximum expiratory flow (PEF) should be performed for differentiation. In a small number of patients, these two diseases may overlap.