Bronchiectasis is most often seen in children and young adults. Most of them are secondary to acute or chronic respiratory tract infections and bronchial obstruction, resulting in abnormal and persistent bronchial dilatation due to repeated bronchial inflammation and structural destruction of the bronchial wall. The clinical manifestations are mainly chronic cough, coughing up large amounts of pus sputum and/or repeated hemoptysis. In recent years, the incidence of acute and chronic respiratory infections has tended to decrease with proper treatment.
Etiology and pathogenesis
The main etiology of bronchiectasis is bronchio-pulmonary tissue infection and bronchial obstruction. Both interact with each other and contribute to the onset and development of bronchiectasis. Bronchiectasis may also be caused by congenital developmental disorders and genetic factors, but is less common. The etiology of bronchiectasis is unknown in about 30% of patients, but usually diffuse bronchiectasis occurs in patients with genetic, immune or anatomical defects such as cystic fibrosis, ciliary dyskinesia and severe al-antitrypsin deficiency. Hypoimmunoglobulinemia and immunodeficiencies and rare structural abnormalities of the airways can also cause diffuse disorders such as tracheobronchial dilatation (Mounier-Kuhn syndrome), cartilage defects (Williams-Campbell syndrome), and rare complications of common diseases such as allergic bronchopulmonary aspergillosis. Focal bronchiectasis can arise from untreated pneumonia or obstruction, such as a foreign body or tumor, exogenous compression or anatomic displacement after lobectomy. Predisposing factors for bronchiectasis are shown in Table 2-4-1.
All of these diseases impair host airway clearance mechanisms and defenses, making them less capable of clearing secretions and susceptible to infection and inflammation. Repeated bacterial infections can cause progressive enlargement, scarring and distortion of airways filled with inflammatory mediators and pathogenic bacterial mucous fluid. The bronchial walls thicken due to edema, inflammation and new blood vessel formation. Nontuberculous mycobacteria also cause bronchial dilatation in patients. Destruction of the surrounding interstitial tissue and alveoli leads to fibrosis, emphysema, or both.
Pathology
Bronchiectasis is often a disruption and inflammatory change located in the walls of segmental or subsegmental bronchi, where the structures of the affected walls, including cartilage, muscle, and elastic tissue, are destroyed and replaced by fibrous tissue. Dilated bronchi may accumulate thick purulent secretions, and their peripheral airways are often obstructed by secretions or replaced by fibrous tissue occlusion. Dilated bronchi include three different types. (1) Columnar dilatation: the bronchi are uniformly dilated and suddenly thin in one place, and the distal small airways are often obstructed by secretions. (ii) Cystic dilatation: The dilated bronchial lumen is cystically altered, and the blind end of the bronchus also has an unidentifiable cystic structure. (iii) Irregular dilatation: The diseased bronchial lumen shows irregular changes or bead-like changes. Microscopically, bronchial inflammation and fibrosis, bronchial wall ulceration, squamous epithelial metaplasia and mucus gland hyperplasia were seen. Fibrosis, emphysema, bronchopneumonia, and pulmonary atrophy may also be present in the lung parenchyma adjacent to the diseased bronchi. Inflammation may result in increased vascularity in the bronchial wall with corresponding bronchial artery dilatation and anastomosis of the bronchial artery and pulmonary artery.
Clinical manifestations
(A) Symptoms
1. Chronic cough, large amount of pus sputum Related to the change of position, this is due to the accumulation of secretions at the site of bronchial dilatation, and the secretions stimulate the bronchial mucosa when changing the position causing cough and sputum discharge. Its severity can be estimated by sputum volume: mild,
2. Recurrent hemoptysis 50%-7O% of patients have hemoptysis of varying degrees, ranging from blood in the sputum to massive hemoptysis, with the amount of hemoptysis sometimes inconsistent with the severity of the disease and the extent of the lesion. Some patients have recurrent hemoptysis as the only symptom, which is clinically known as “dry bronchiectasis”, and the lesions are mostly located in the upper lobe bronchi with good drainage.
3. Recurrent pulmonary infections are characterized by recurrent pneumonia in the same lung segment and persist. This is due to the loss of function of the dilated bronchus to clear secretions, poor drainage, and easy recurrence of infection.
4, chronic infection poisoning symptoms such as repeated infections, may appear fever, fatigue, loss of appetite, wasting, anemia, etc., children may affect development.
(B) Physical signs
In early stage or dry bronchiectasis, there may be no abnormal pulmonary signs, but in case of heavy lesions or secondary infection, a fixed and persistent limited coarse wet stalls in the lower chest and back can often be smelled.
Laboratory tests and others
On chest X-ray, the airway of cystic bronchiectasis appears as a significant cystic lumen, and a gas-fluid plane may be present in the lumen (Figure 2-4-1). In the absence of air-fluid planes in the cystic lumen, it is difficult to differentiate from emphysema herpetiformis or cellular lung with severe interstitial lung lesions. Other manifestations of bronchiectasis are thickening of the airway walls, mainly due to peribronchial inflammation. The dilated airways tend to converge due to hyperventilation and atrophy of the affected lung parenchyma, which may appear as a “double-track sign” in longitudinal views and a “ring shadow” in transverse views. This is due to the fact that the dilated airway is filled with secretions and the lumen appears denser than the translucent area, producing an opaque duct or branching tubular structure. However, this test lacks specificity in determining the presence or absence of bronchiectasis, and imaging may be normal when the lesion is mild.
The imaging test that can definitively diagnose bronchiectasis is bronchography, which is the direct visualization of dilated bronchi by dripping an opaque iodine lipid contrast on the airway surface through a catheter or bronchoscope. However, because this technique is invasive, it has been replaced by CT, which can also clearly visualize dilated bronchi in cross-section (Figure 2-4-2). The advent of high-resolution CT (HRCT) has further improved the sensitivity of CT in diagnosing bronchial dilatation. It has now become the main diagnostic method for bronchiectasis because it is noninvasive, easily reproducible, and readily accepted by patients.
Other tests are useful for visual or etiologic diagnosis of bronchiectasis. Fiberoptic bronchoscopy may reveal crater-like changes when bronchial dilatation is focal and located above the segmental bronchus. Sputum examination often shows an abundance of neutrophils and a variety of colonized or infected microorganisms. Sputum smear staining as well as sputum bacterial culture results can guide antibiotic therapy. Pulmonary function measurements can confirm airflow limitation due to diffuse bronchiectasis or associated obstructive lung disease.
Diagnosis and differential diagnosis
(I) Diagnosis
A definite diagnosis of bronchiectasis can be made based on a history of recurrent purulent sputum and hemoptysis and a history of previous respiratory infections that induce bronchiectasis, and HRCT showing abnormal imaging changes of bronchiectasis. Fibrinoscopy or local bronchogram can clarify the site of bleeding, dilatation or obstruction. Local lavage can also be performed via fibrinoscopy, and specimens of lavage fluid can be taken for smear, bacteriological and cytological examination to further assist diagnosis and guide treatment.
(ii) Differential diagnosis
The diseases that need to be differentiated from bronchiectasis are mainly chronic bronchitis, lung abscess, tuberculosis, congenital lung cyst, bronchopulmonary carcinoma and diffuse panbronchiectasis, etc. Careful study of the medical history and clinical manifestations, as well as reference to the features of chest X-ray, HRCT, fiberoptic bronchoscopy and bronchography can often make a clear differential diagnosis. The following points have some reference significance for differential diagnosis: ① Chronic bronchitis: it occurs mostly in middle-aged patients and above, and the cough and sputum are obvious in winter and spring when the climate is changeable, mostly white mucus sputum, and purulent sputum may appear during acute attacks of infection, but there is no history of repeated hemoptysis. On auscultation, scattered dry and moist woven wool can be heard in both lungs, and on X-rays, dense local inflammatory shadows with cavitary fluid can be seen. Acute lung abscesses can be treated with effective antibiotics and the inflammation can be completely absorbed and subside. In case of chronic lung abscess, there is mostly a past history of acute lung abscess. ③Pulmonary tuberculosis: there are often symptoms of tuberculosis toxicity such as low fever, night sweats, malaise, wasting, etc. The diagnosis can be made by dry and wet sternal bridle swings and admonition to play the dried X-ray chest film and sputum tuberculosis bacillus examination. ④ Congenital pulmonary cyst: X-ray examination reveals multiple round or elliptical shadows with slender borders, thin walls, and no inflammatory infiltration of surrounding tissues. Chest CT examination and bronchography can help to make the diagnosis. ⑤ Diffuse panbronchitis: with chronic cough, sputum, dyspnea on activity, often accompanied by chronic sinusitis, chest radiograph and chest CT show diffusely distributed small nodular shadows, and macrolide antibiotic treatment is effective.
Treatment
(I) Treatment of underlying disease
Active pulmonary tuberculosis with bronchiectasis should be treated with active antituberculosis therapy, and immunoglobulin replacement therapy is available for hypoimmunoglobulinemia.
(2) Control of infection
Antibiotics should be applied when there are signs of acute infection such as increase in sputum volume and its purulent components. Antibiotics can be guided by sputum Gram stain and sputum culture, but empirical treatment (e.g., ampicillin, amoxicillin, or cefaclor) is often required at the beginning. In the presence of Pseudomonas aeruginosa infection, oral quinolones and intravenous aminoglycosides or third-generation cephalosporins are options. In patients with chronic purulent sputum, in addition to a short course of antibiotics, a longer course of antibiotics, such as oral amoxicillin or inhaled aminoglycosides, or intermittent and regular use of a single antibiotic as well as rotation of antibiotics, may be considered.
(iii) Improvement of airflow limitation
Bronchodilators can improve airflow limitation and help clear secretions, and are often effective in patients with airway hyperreactivity and reversible airflow limitation.
(iv) Removal of airway secretions
Phlegmolytic drugs, as well as chest physiotherapy such as vibration, back tapping and postural drainage, can help clear airway secretions. To improve secretion clearance, postural drainage and nebulized inhalation of recombinant deoxyribonuclease, which reduces sputum viscosity by blocking DNA release from neutrophils, should be emphasized.
(v) Surgical treatment
If the bronchiectasis is limited and recurrent recurrence persists despite adequate medical treatment, surgical resection of the diseased lung tissue may be considered. If the hemorrhage comes from a hyperplastic bronchial artery, and if conservative treatment such as rest and antibiotics do not relieve recurrent hemoptysis, surgery may be considered for those with limited lesions, otherwise bronchial artery embolization is used. In cases of disability despite all treatment, lung transplantation may be considered in appropriate cases.
Prognosis
Depends on the extent of bronchiectasis and the presence of complications. In cases with limited bronchiectasis, aggressive treatment will rarely affect quality of life and longevity. Extensive bronchiectasis can impair lung function and even lead to respiratory failure, resulting in death. Massive hemoptysis can also seriously affect the prognosis.