Respiratory system diseases are the most common and frequently occurring diseases, among which respiratory system diseases are one of the 'four chronic diseases' that seriously endanger people's health. Fourth place. To achieve the goal of preventing chronic respiratory diseases, early detection and early intervention are the keys, and pulmonary function testing is the key technology.

What are the common respiratory diseases?

· Asthma

· Lung infection

· Bronchiectasis


· Occupational lung disease

· Acute and chronic cough

· Rhinitis

· Sore throat

· Pediatric Respiratory Disorders

· Cold and cough

· Bronchitis

The clinical significance of pulmonary function tests

The diagnosis and differential diagnosis

1. Early diagnosis of lung and airway diseases

2. Diagnose the lesion site

3. Identify the cause of dyspnea

2. Condition assessment

1. Severity assessment

2. Assess the tolerance and complication risk of thoracoabdominal surgery

3. Assess labor intensity and tolerance

3. Guided treatment

4. Monitoring

1. Monitor the changes and prognosis of the disease

2. Monitoring of critically ill patients

Early detection of COPD

Pulmonary function testing is the most effective method for detecting early COPD (chronic obstructive pulmonary disease).

Neither X-ray nor arterial blood gas analysis can detect COPD before shortness of breath has progressed to a severe degree; in the early stages of the disease, only pulmonary function tests can detect COPD.

Pulmonary function assays can detect COPD 5-10 years earlier than other methods.

Pulmonary ventilation function

Forced Vital Capacity FVC

1. Forced vital capacity (FVC) refers to the deep inhalation to the total lung capacity, and then the forced and rapid exhalation to the residual capacity. The measured vital capacity is called forced vital capacity, and the exhaled air volume in 1, 2, and 3 seconds is measured at the same time, and is called forced expiratory volume in first second (FEV1), forced expiratory volume in second second (FEV2), Forced expiratory volume in the third second (FEV3).

2. FEV1/FVC is called the forced expiratory rate in the first second, that is, the one-second rate.

3. Maximum mid-expiratory flow rate (MMEF): Divide the forced vital capacity into four equal parts, and divide the exhaled mid-half volume by the time spent in liters/second.

    Normal range: FVC%Pred ≥80%

                            FEV1%Pred ≥80%

                            FEV1/FVC ≥70%

Clinical Significance

1. The FVC of normal people is close to the VC, but in patients with obstructive pulmonary disease, due to the increased intrathoracic pressure and the premature closure of the small airways, the FVC can be smaller than the VC.

2. Evaluation of ventilatory dysfunction:

· Obstructive disease FEV1/FVC% decreased, the curve slope is flat, while restrictive disease FEV1/FVC% normal or increased, the curve is steep, forced vital capacity is usually completed ahead of schedule.

· FEV1/FVC% can detect airflow obstruction sensitively, and FEV1%pred helps to judge the degree of airflow obstruction. When grading the severity of chronic obstructive pulmonary disease (COPD), the index of FEV1%pred is generally used.

Portable spirometer Air Smart

In response to the above-mentioned respiratory diseases, the Raffles Institute of Nebulization Medicine has launched the Air Smart, a portable lung function tester.