Decreased lung capacity

Introduction Total lung capacity: refers to the maximum volume of lungs that can be accommodated, which is equal to the sum of tidal volume, supplemental inspiratory volume, supplemental expiratory volume and residual gas volume. It is also equal to the sum of the deep inspiratory volume and the functional residual gas volume. Adult males average about 5,000 ml and women about 3,500 ml. Vital capacity (VC): refers to the amount of gas exhaled for maximum exhalation after maximal inhalation. The lung capacity is equal to the sum of tidal volume, supplemental inspiratory volume and supplemental expiratory volume, which is also equal to the total lung capacity minus the residual gas volume. Normal adult males average about 3,500 ml and women about 2,500 ml. Lung capacity reflects the maximum capacity of a lung in a single ventilation. Generally speaking, the greater the lung capacity, the better the ventilation function of the lung. During the breathing cycle, the lung volume changes with the amount of gas entering and leaving the lungs, and the lung capacity increases during inhalation and decreases during exhalation. The magnitude of the change is mainly related to the depth of breathing. Certain respiratory diseases or chest surgery can cause a pathological decrease in lung capacity.

Cause

1. Thoracic surgery: 1 to 3 days after chest surgery, due to the inhibition of anesthetic drugs, surgical trauma and chest strap fixation, respiratory frequency and amplitude can be reduced, and lung capacity can be reduced.

2, respiratory diseases, such as: idiopathic pulmonary interstitial fibrosis.

an examination

Related inspection

Pulmonary ventilation function pulmonary ventilation imaging lung volume alveolar gas-arterial oxygen partial pressure difference intrapulmonary sub-flow (Qsp, Qs/Qt)

diagnosis:

Idiopathic pulmonary interstitial fibrosis:

First, clinical manifestations

1. After more than 50 years of age, the onset is concealed, mainly in the progressively aggravated activities of breathing difficulties and dry cough, the course of disease for several months or even years. It can be accompanied by symptoms such as general malaise, fatigue and weight loss, but rarely fever.

2. At the bottom of the lungs, you can smell a small pop sound or a Velcro rake and a clubbing or toe. Signs of obvious purpura, pulmonary hypertension, and right heart dysfunction can be seen in the late stage.

Second, auxiliary inspection

1. Chest X-ray examination: The typical signs are diffuse reticular or net nodular interstitial exudation based on the base and outer band of both lungs, and the volume of the honeycomb lung and lung is reduced. 5-10% of IPF patients had normal chest X-rays at the first visit.

2. Chest CT: In particular, high-resolution CT (HRCT) is more sensitive than traditional X-ray films in assessing the extent and nature of lung parenchymal abnormalities. HRCT showed a reticular shadow of the subpleural and basal parts of both lungs and a honeycomb lung with traction bronchiectasis. There may be a focal glass-like change, and pleural or mediastinal lymph nodes are rare.

3. Pulmonary function: manifested as decreased lung volume or vital capacity, decreased DLco or decreased DLco/alveolar ventilation (VA), and hypoxemia.

4. Bronchoalveolar lavage (BAL) and transbronchial lung biopsy (TBLB): BAL examination showed an increase in neutrophils and/or eosinophils, while lymphocyte increase was not significant. Because TBLB is too small, it is impossible to make a pathological diagnosis of UIP. Therefore, the main significance of BAL or TBLB is to exclude other diseases and narrow the scope of differential diagnosis.

5. Blood tests for lactate dehydrogenase (LDH), erythrocyte sedimentation rate (ESR), antinuclear antibodies (ANA), and rheumatoid factor (RF) can be slightly elevated.

6. Surgical lung biopsy (thoracotomy or thoracoscopic surgery): Surgical lung biopsy is a diagnostic method for IPF. For patients whose diagnosis is unclear, patients with no surgical contraindications should consider surgical lung biopsy. The pathological diagnosis is UIP.

Although IPF has these characteristics, these manifestations of IPF can also be seen in other interstitial lung diseases. Therefore, it is necessary to first pass a comprehensive and detailed medical history, physical examination and corresponding laboratory tests to exclude interstitial lung diseases caused by other causes.

Differential diagnosis

Need to be identified with the following symptoms:

1. Pulmonary hyperinflation: The lungs are over-inflated, which is commonly referred to as emphysema. Emphysema refers to the airway elasticity of the distal bronchioles (breathing bronchioles, alveolar ducts, alveolar sacs, and alveoli), excessive expansion, inflation, and increased lung volume or pathological conditions associated with airway wall destruction. . According to the cause of the disease, emphysema has the following types: senile emphysema, compensatory emphysema, interstitial emphysema, focal emphysema, paraventricular emphysema, obstructive pulmonary qi swollen.

2. Increased lung water content: pulmonary edema and pathological state of increased lung water content caused by fluid exchange dysfunction between blood vessels and tissues in the lung, regardless of the cause of pulmonary edema, the respiratory pathophysiology is substantially the same, ie Fluid retention in the lungs and gas exchange disorders, lung compliance decreased, ventilation / blood flow imbalance, leading to hypoxemia. The clinical manifestations were sudden onset, difficulty in breathing, hair set, frequent cough, a lot of foamy sputum, diffuse wet warm sounds in both lungs, and X-ray showed a butterfly-shaped blushing shadow on both lungs. Pulmonary edema can seriously affect respiratory function, which is a common respiratory emergency. The target of treatment is aimed at pathophysiology and basic diseases. Early diagnosis and treatment play a decisive role in the prognosis and outcome of pulmonary edema.

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