Pulmonary alveoli are usually secondary to inflammatory lesions of the small bronchi, such as pneumonia, emphysema, and tuberculosis, and most often coexist clinically with emphysema.
Pulmonary alveoli secondary to pneumonia or lung abscess are most often seen in infants and children, either singly or in multiple cases. Due to inflammatory lesions, the small bronchial mucosa has edema, resulting in partial obstruction of the lumen, which produces a live door effect, and the air can enter the alveoli but not easily discharged, and the pressure inside the alveoli increases, and the alveolar interval gradually ruptures due to the increased pressure inside the alveoli, forming a huge air-containing cavity, which is clinically called a large alveolus; those secondary to tuberculosis are mostly solitary, and no obvious emphysema exists at the same time; those secondary to emphysema are often multiple In cases secondary to pulmonary tuberculosis, they are often multiple, and in addition to large alveoli, they are often accompanied by numerous small alveoli.
Clinical manifestations
1. Symptoms and signs: The walls of the alveoli are very thin and consist of flattened epithelial cells of the alveoli, or they may only be fibrous membranes. They can coexist with a variety of emphysema, commonly in parasternal or lobar emphysema, and may be accompanied by carbon deposits, such as coal miner’s pneumoconiosis, or without carbon deposits, such as scar tissue emphysema. Pulmonary alveoli are classified into three types according to pathological morphology.
1.1 Type I: Narrow-necked pulmonary alveoli. It protrudes from the lung surface and has a narrow band attached to the lung. Because of the live valve obstruction formed by bronchial scar tissue, the alveoli increase in size is due to alveolar side branch ventilation and gas stagnation. Type I alveoli are thin-walled, often formed by pleura and connective tissue, and occur mostly in the middle lobe or lingual lobe, but also commonly in the upper lobe of the lung, probably because of the high negative pressure in the chest cavity in this area, and the presence of alveoli can be detected on conventional chest radiographs.
1.2 Type II: Wide basal superficial pulmonary alveoli. It is located in the superficial lung layer, between the dirty pleura and emphysematous lung tissue. A connective tissue septum is visible in the lumen of the alveoli, but it does not form the wall of the alveoli and can be seen in any part of the lung.
1.3 Type III: Wide basal deep alveoli. The structure is similar to type II, but the site is deeper, surrounded by emphysematous lung tissue, and the alveoli may extend to the hilum, and can be seen in any lobe of the lung.
1.4 When the alveoli increase in size, the surrounding lung tissue is compressed and causes displacement of the lung. The compressed lung tissue appears as an increased density shadow around the alveoli on X-ray chest radiographs. All the above three types are seen in chronic bronchitis. Small lobe central emphysema is not complicated by pulmonary alveoli. Lower lobe pulmonary alveoli are commonly seen in coal miner’s pneumoconiosis and fused silicosis with complications.
1.5 Small alveoli do not cause symptoms by themselves, and patients with simple alveoli are often asymptomatic; some alveoli may remain unchanged for many years, and some may gradually increase in size. The enlargement of alveoli or the appearance of new alveoli at other sites can cause pulmonary dysfunction and the gradual development of symptoms. Large alveoli can cause chest tightness and shortness of breath. The sudden enlargement and rupture of large pulmonary alveoli can produce spontaneous pneumothorax, which can cause severe dyspnea and also chest pain similar to angina.
1.6 Patients with pulmonary alveoli are often combined with chronic bronchitis, bronchial asthma, and emphysema, and clinical symptoms are also mainly caused by these diseases, only that the clinical symptoms are further aggravated after the formation of pulmonary alveoli. Secondary infection of large pulmonary alveoli can cause cough, coughing, chills and fever, and in severe cases, cyanosis. If the draining bronchus is obstructed, the lung alveolar cavity is filled with inflammatory material and the cavity may disappear. It may occur clinically that the symptoms of infection disappear after treatment, while the large alveolar shadows on chest radiographs persist for weeks or months and do not subside.
Diagnosis and differentiation
1.Medical examination
1.1 Chest X-ray: It is the best way to diagnose pulmonary alveoli. Pulmonary alveoli in the apical part of the lung appear as very thin translucent cavities located at the edge of the lung field, which can be round, oval or flatter rectangular, varying in size, and in larger alveoli, sometimes transverse intervals can be seen. Multiple alveoli may be grouped together in a multifaceted fashion. They are usually not in direct communication with the larger bronchi, have no fluid level, and are not accessible to bronchial contrast agents. The alveoli at the base of the lungs are often not easily seen on the orthopantomogram, and some can be located completely below the level of the diaphragm apex, while others are only partially above it. The walls of the alveoli are easily mistaken for curtain-top pleural adhesions if they do not show a coherent circular line shadow. Giant alveoli are usually tense and may be surrounded by a layer of compressive atelectasis, making the alveolar wall appear thick and indistinct close to the chest wall. The nearby lung is pushed and causes partial atelectasis, and the lung texture is clustered and less translucent. The alveoli may fuse with each other to form a large, dominant alveolus, resembling a confined pneumothorax. The alveoli may also rupture and produce a restrictive pneumothorax.
1.2 Fluoroscopy and expiratory-phase chest radiographs: help to detect alveoli, which appear relatively larger and have clearer margins due to gas retention during expiration. Tomography is also helpful in clarifying the outline of the alveoli and showing compression and displacement of the surrounding lung tissue. In cases of coexisting lobar emphysema, tomograms may also show abnormalities in the shape of the pulmonary vessels.
1.3 CT examination: It can reveal large pulmonary alveoli under 1 cm in diameter that are not easily revealed by ordinary chest X-ray.
1.4 Pulmonary angiography: It can accurately show the degree of pulmonary vascular damage and the compression of blood vessels around large pulmonary alveoli.
2.Diagnostic basis
2.1 History of chronic cough, shortness of breath during activity, and in some cases, recurrent spontaneous pneumothorax.
2.2 X-ray or CT examination: there are vesicle-like changes in the lung, with most of the striated shadows in different directions in the vesicles, and no lung texture in the vesicles. The walls of the vesicles are thin, and some of them have liquid air surface in the cavity.
3.Diseases easily misdiagnosed
3.1 Restricted pneumothorax: The main point of differentiation between pulmonary alveoli and restricted pneumothorax is that the alveoli expand in all directions, so the compressed lung tissues can be seen in the apical region of the lung, the angle of the cribriform septum or the angle of the cardiodiaphragm; whereas restricted pneumothorax mainly pushes the lung tissues into the lung, and the edges of the compressed lung are usually seen to shrink toward the hilum, which is not seen in pulmonary alveoli. Thus although striated septa are seen in both, a distinction can still be given.
3.2 Tuberculosis cavity: Inflammation occurring in one of the small bronchi, resulting in local congestion and swelling. Because of the sticky secretions and bronchospasm, the small bronchi are narrowed or obstructed in a flap-like manner, so that air can enter the lungs during inspiration but not all the gas can be expelled during expiration. The air inside the alveoli becomes more and more, and the pressure gradually increases, causing the alveoli to over-expand and rupture to form alveolar emphysema, which fuses with each other to form large alveoli. The alveoli are only indirectly connected to the bronchi, so the gas is not easily expelled and can often be maintained for several years without change. In some cases, progressive alveoli may form and continue to expand until one lung is replaced by a large alveolus. Large pulmonary alveoli are not uncommon, but are easily confused with tuberculous cavities. However, tuberculous cavity is formed by the dissolution and discharge of case-like material, usually with thick walls, nearby tuberculous lesions and infiltrates, and tuberculosis bacteria can be detected in sputum, which can be differentiated by effective anti-tuberculosis treatment.
3.3 Spontaneous pneumothorax
3.31 Although both are compression of lung tissue by gas cavities, the contours of their formation and the morphology of their compression of the lung differ due to the location of the gas. Giant alveoli are formed by the rupture and enlargement of alveoli in the lung tissue, pushing the lung tissue around and compressing it in an “eccentric” manner. Spontaneous pneumothorax is the rupture of the dirty pleura, small trachea and alveoli are connected with the thoracic cavity, and a large amount of gas enters the thoracic cavity and compresses the lung tissue inward, forming “centripetal” compression, (with the exception of those with pleural adhesions). If the compression is light in idiopathic pneumothorax, a translucent area is formed in the outer zone of the lung field, and the edges of the lung tissue can be seen curving inward. In case of tension pneumothorax, the lung tissue may be pushed near the hilum, forming a circular mass-like shadow.
3.32 Once formed, giant alveoli can exist for many years, and the transillumination zone may remain unchanged on repeated review. Clinical signs and symptoms may persist for a long time. The onset of spontaneous pneumothorax is often rapid, and the fluoroscopic area may expand or shrink significantly on review within a short period of time.
3.33 Giant pulmonary alveoli without co-infection usually do not contain fluid and have no liquid-air plane. If the pneumothorax is not treated reasonably, it will form liquid pneumothorax in a short period of time.
3.34 Chest puncture, manometry and suction are generally contraindicated in giant alveoli, because puncturing the dirty layer of the pleura is likely to cause pneumothorax and aggravate the condition. If puncture manometry is done for misdiagnosed gas, the pressure fluctuation when breathing gas belongs to atmospheric pressure, fluctuating above and below “0”, and the transillumination area does not shrink and the symptoms do not improve after aspiration, while the pressure of tension pneumothorax is higher than atmospheric pressure when puncture manometry, fluctuating above “0 When the pressure fluctuates above “0” during puncture pressure measurement, it can be significantly decreased immediately after pumping, and the symptoms can be improved, and the transillumination area can be significantly reduced when the film is reviewed.
3.4 Congenital pulmonary cyst.
3.5 Diaphragmatic hernia.
3.6 Lung abscess and other diseases are differentiated.
4. Treatment of disease
1.1 Asymptomatic pulmonary alveoli do not require treatment. In patients with chronic bronchitis or emphysema, the primary lesion is treated. In case of secondary infection, antibiotics are applied.
1.2 In patients with large pulmonary alveoli, occupying 70% to 100% of one side of the chest cavity and clinically symptomatic without other lung lesions, surgical removal of the alveoli can reopen the compressed lung tissue, increase the respiratory area, disappear the intrapulmonary shunt, increase the partial pressure of arterial blood oxygen, reduce the airway resistance, increase the ventilation volume, and the patient’s symptoms of dyspnea such as chest tightness and shortness of breath can be improved.
1.3 As much healthy lung tissue as possible should be preserved during surgery, and strive to perform only alveolar resection and suture, or local wedge resection of lung tissue to avoid unnecessary loss of lung function.
1.4 Spontaneous pneumothorax caused by ruptured pulmonary alveoli can be cured by non-surgical treatments such as thoracentesis and closed thoracic flow, but spontaneous pneumothorax that occurs repeatedly should be treated by surgical methods. During surgery, the alveoli are ligated or sutured, while tetracycline or 2% iodine can be used to coat the chest cavity to fix the pleural adhesions and prevent the recurrence of pneumothorax.
1.5 Patients with combined hemopneumothorax sometimes have heavy clinical symptoms, often with chest pain and dyspnea, and also a series of manifestations of internal bleeding. Clinically, changes in the condition should be closely observed, and non-operative measures, such as blood transfusion and thoracentesis, should be taken within a short period of time, and when the symptoms do not improve significantly, open-chest exploration should be performed decisively. At this time there is often a large active bleeding, non-surgical treatment observation time is often too long to delay the disease, the prognosis is not as good as surgical hemostasis.
5.Disease prevention
1.1 Although there are no special requirements for diet, nutrition should be increased, more high-quality protein, more vitamin-rich food, less stimulating food and drinks, avoid smoking and alcohol, and avoid infection.
1.2 Patients and family members are often worried about the cost, surgical efficacy and even fear of surgery, so careful psychological care during the perioperative period can relieve patients’ tension and reduce stress reactions.
1.3 Preoperative respiratory preparation such as smoking cessation, deep breathing training, and effective coughing and sputum excretion can improve the clearance of secretions, release bronchospasm, and reduce respiratory secretions.
1.4 Respiratory care is especially important when preventing complications: after surgery, low-flow continuous oxygen should be given, deep breathing should be encouraged, and turning and patting the back once every 2 hours; psychological care should be done to avoid refusal to cough and sputum because of pain or fear of tube dislodgement; patients should learn the correct method of sputum excretion, such as: holding the breath after deep inspiration, coughing gently several times to cough up sputum to the pharynx while pressing the chest, and finally coughing hard to cough up sputum; if sputum is If the sputum is sticky, drink more water to dilute the sputum and facilitate its discharge.
6.Complications: Spontaneous pneumothorax is the most common complication of pulmonary alveoli, followed by infection and spontaneous hemopneumothorax.
1.1 Spontaneous pneumothorax: Pulmonary alveoli can be asymptomatic. When the pressure suddenly increases during sudden exertion, such as violent coughing, heavy lifting or sports, the pulmonary alveoli rupture and gas enters the pleural cavity from the lung, forming spontaneous pneumothorax, dyspnea, shortness of breath, shortness of breath, panic, and rapid pulse may occur, etc. The pneumothorax makes the negative pressure in the pleural cavity disappear, and the gas compresses the lung tissue to make it atrophy toward the pulmonary hilum, and the degree of atrophy depends on the amount of gas entering the pleural cavity, as well as the original pathology of the lung and pleura The degree of atrophy depends on the amount of gas entering the chest cavity and the pathology of the original lesions of the lung and pleura. If the amount of gas entering the chest cavity is large, the original lesions of the lung tissue are light and the compliance is still good, the lung atrophy is more, sometimes it can reach 90% of one side of the chest cavity. If the patient has emphysema, pulmonary fibrosis, long-term chronic infection of lung tissue in addition to alveoli, when the alveoli rupture, although part of the gas enters the chest cavity, and the degree of lung tissue atrophy can be less, but because the patient’s original lung function has been reduced, the symptoms are also more serious. x-ray can be seen in the compressed lung formed by the pneumothorax line, if there are adhesions, the pneumothorax line is irregular. After the rupture of the pulmonary alveoli, a small part of the fissure is small, and the fissure closes by itself after the atrophy of the lung tissue, the air leakage stops, the air accumulation in the chest cavity is gradually absorbed, the negative pressure in the chest cavity is restored, and the lung reopening is healed.
1.2 Tension pneumothorax: If the alveoli rupture forms a live valve, the negative thoracic pressure increases when inhaling, the gas enters the thoracic cavity, and the live valve closes when exhaling, the gas cannot be discharged, especially when coughing, the airway pressure increases when the vocal valve is closed, the gas enters the thoracic cavity, and after the vocal valve opens, the airway pressure decreases and the cleft closes again, the amount of gas in the thoracic cavity increases with each breath and cough, and a tension pneumothorax is formed. In tension pneumothorax, the lung tissue on the affected side is completely atrophied and the mediastinum is pushed to the healthy side, while the lung tissue on the healthy side is also compressed and the large blood vessels of the heart are displaced and the large veins are distorted and deformed, which affects the blood return and causes serious obstruction to the respiratory circulation, and the patient may experience respiratory distress, rapid pulse, decreased blood pressure, and even asphyxia and shock. The affected side of the thorax is elevated, mostly accompanied by subcutaneous emphysema on the affected side, and the trachea is obviously displaced to the healthy side, which is critical and often requires emergency treatment.
1.3 Spontaneous hemothorax: Spontaneous hemothorax caused by large pulmonary alveoli, most of which bleed from adhesions and adhesive tearing activities of the lung tissue around the large alveoli or large alveoli in the apical part of the lung with the roof of the chest. The small arteries in the adhesion zone can be up to 0.2 cm in diameter, and the vessels originate from the body circulation with higher pressure, while the thoracic cavity is under negative pressure, which increases the tendency of bleeding. In addition, the bleeding is difficult to stop automatically because the blood in the thoracic cavity does not coagulate due to the defibrotic effect of lung, heart and diaphragm movements. Clinical symptoms may vary depending on the speed of bleeding. When bleeding is slow, patients may present with gradually increasing chest tightness, dyspnea, blunted diaphragm angle visible on X-ray, or parabolic images of pleural effusion. When the bleeding is rapid, there can be shock manifestation in a short period of time.
1.4 Spontaneous hemopneumothorax: When the adhesions of the pulmonary alveoli and surrounding lung tissues to the chest wall are torn, if there are blood vessels ruptured in the adhesion zone and the lung tissues are damaged at the same time, spontaneous hemopneumothorax is formed.
1.5 Secondary infection of pulmonary alveoli: In most cases, pulmonary alveoli occur at the distal end of the bronchi above the eighth level, and most of them are not infected, but if the draining bronchi are blocked and the bronchi of pulmonary alveoli are filled with inflammatory secretions, the patient may develop fever, cough, cough and other symptoms of infection, and sometimes after anti-infection treatment, the clinical symptoms improve, while the signs of infection on chest X-ray can still persist for a longer period of time.