Lung agenesis is a congenital pathology of the development of the respiratory organs, in which the lung tissue and the main bronchus of one or both lungs are completely absent. In rare cases, it is asymptomatic, more often there is a cough with scant discharge, shortness of breath with little physical exertion, asymmetry of the chest and the lag of its corresponding half in the act of breathing. Pathology is diagnosed using radiation methods of examination of the thoracic cavity, bronchoscopy. Symptomatic treatment is carried out aimed at eliminating hypoxia and relieving inflammatory processes in the upper and lower respiratory tract.
33.3 Lung agenesis
Lung agenesis refers to rare malformations of the respiratory system. Among all congenital anomalies of the respiratory tract, this pathology ranks 13th in frequency of occurrence and is observed in 1 out of 15 thousand newborns. It is more often detected in boys. Some authors of medical articles on clinical pulmonology use the term “agenesis” in relation to lung aplasia, in which there is a fully developed main bronchus, but there is no pulmonary parenchyma. Bilateral agenesis or aplasia of the lungs is incompatible with life. In 30% of cases, the right lung is missing. The defect is often combined with other, often multiple anomalies of the development of various organs and systems.
Causes of lung agenesis
Lung agenesis is the result of stopping the development of the rudiment of the bronchial kidney, the laying of which occurs at the early (3-4 weeks of gestation) stages of embryogenesis. The impact of adverse external factors on the body of a pregnant woman for up to 16 weeks can cause violations of the formation of the respiratory system. Congenital defects of the respiratory system occur due to mechanical trauma, the effects of ionizing radiation and other harmful physical and chemical factors.
The cause of agenesis or aplasia of the lungs can be diseases of the mother of viral or bacterial etiology, taking medications with teratogenic side effects, active or passive smoking. Sometimes the absence of a lung is observed with some chromosomal aberrations. The literature describes cases of familial hypoplasia and aplasia of alveolar tissue. A certain importance in the formation of the defect has a lack of water in a pregnant woman, provoking the appearance of deformities of the chest in the fetus, diaphragmatic hernias. There is a close relationship of pathology with renal agenesis and other abnormalities of the urinary system.
In the complete absence of one lung, there is a vicarious increase in the second, displacement of the heart and main vessels. The only large lung occupies both hemithorax. Right-sided agenesis is accompanied by a maximum displacement of the mediastinum to the right. In the absence of the left lung, the heart turns around the longitudinal axis of the body so that its tip is located in the lateral part of the chest cavity. The trachea, which does not have a membranous part, smoothly, without forming a bifurcation, passes into the main bronchus. There are no pulmonary vessels.
With lung aplasia, there is a tracheal bifurcation and a blindly ending main bronchus, the diameter of which is usually smaller than the corresponding bronchus on the healthy side. There is no alveolar tissue and bronchial tree. The only lung, as a rule, is not able to provide a full-fledged gas exchange, therefore, chronic hypoxia develops. It is aggravated by inflammatory processes that join later. The displacement of the mediastinum leads to the occurrence of cardiovascular insufficiency.
Symptoms of lung agenesis
Pathology may not bother the patient for a long time and be detected accidentally during examination for another reason. However, more often respiratory failure is detected already in early childhood. The baby does not take the breast well, gets tired quickly and falls asleep while sucking. The nasolabial triangle turns blue during feeding. Sick children lag behind in physical development, they have a decrease in exercise tolerance. Shortness of breath, which occurs during physical exertion, progresses as the child grows and becomes permanent.
Respiratory infections are severe, with severe respiratory insufficiency, unproductive cough. Children often complain of chest pains. The chest is deformed. There is a flattening or sinking of one of the halves, its lag during breathing. Patients have signs of distal hypertrophic osteoarthropathy – thickening of the terminal phalanges of the fingers like drumsticks, nail changes in the form of watch glasses. Agenesis of lobes or segments of the lungs has no clinical significance.
Lung agenesis during the first year of life leads to the death of 30-50% of children born with this defect. The immediate cause of death is acute respiratory failure, purulent-inflammatory processes of a single lung, concomitant defects of the central nervous system, heart and urinary system. Right-sided agenesis is more severe, more often combined with other congenital anomalies. With aplasia, there may be an inflection of the trachea, displacement of the aorta and pulmonary trunk associated with bifurcation, which leads to severe pulmonary heart failure.
A pulmonologist is engaged in diagnostic search for suspected lung agenesis. When collecting anamnesis, the prescription of the disease, the presence of other congenital anomalies is specified. During the examination, attention is drawn to the characteristic deformities of the chest, distal phalanges of the fingers. The final diagnosis is based on the following data:
- Physical examination. With percussion, there is a sharp shift of cardiac dullness towards the lesion. Palpationally, the apical push is determined in the right or left axillary region. Heart tones are also clearly heard there, in this regard, right-sided agenesis is often mistaken for dextrocardia. There is a shortening of the percussion sound in the projection of the missing organ, but respiratory noises can be heard during auscultation of this area.
- Radiation methods. An overview radiograph of the lungs shows a displacement of the mediastinum in the diseased side. In the upper parts of the affected hemithorax, there is a section of normal lung tissue, which can lead to a diagnostic error. For the purpose of differential diagnosis of this defect with hydrothorax, atelectasis or diaphragmatic hernia, chest CT is performed. The contrast of the tracheobronchial tree during bronchography makes it possible to distinguish lung aplasia from agenesis. Angiopulmonography reveals the absence of pulmonary vessels.
- Endoscopic diagnostics. Bronchoscopy provides an opportunity to detect the absence of carina and one of the main bronchi. With aplasia of the lung tissue, a short, blindly ending bronchus of a relatively small diameter is revealed, often with signs of chronic endobronchitis.
- Functional techniques. The study of the function of external respiration is auxiliary in nature and, together with pulse oximetry, helps to determine the degree of respiratory failure. Restrictive changes of varying severity are determined on the spirogram, blood oxygen saturation is usually reduced. On the electrocardiogram, the voltage is reduced, there are signs of overload of the right parts of the heart, tachycardia and rhythm disturbances.
Treatment of lung agenesis
There are no special therapeutic methods. Symptomatic conservative therapy is prescribed. The main objective of treatment is to maximize the preservation of the functional abilities of a single lung and prevent the development of complications. Oxygen therapy in childhood allows the lung to grow and develop fully. With any inflammatory process of the respiratory tract, a patient with agenesis is hospitalized in a hospital, broad-spectrum antibacterial drugs are prescribed. If severe complications occur, artificial ventilation of the lungs may be required.
Due to the anatomical features of such patients, it is not yet possible to perform lung transplantation. If necessary, surgical treatment of concomitant anomalies of the development of the cardiovascular system, closure of tracheobronchial fistulas, correction of other defects is carried out. The inflections of the trachea arising from aplasia and its compression by the aorta require urgent surgical intervention for vital indications.
Prognosis and prevention
Bilateral aplasia or agenesis of the lungs always leads to stillbirth. Half of children with a unilateral process die at an early age. Sometimes lung agenesis is asymptomatic. The prognosis largely depends on the presence of another combined congenital pathology, which worsens significantly with the addition of a respiratory infection. Any purulent-inflammatory process of the respiratory system is a life-threatening condition for patients with a single lung.
Primary prevention includes a healthy lifestyle of a woman during pregnancy, timely prenatal screening aimed at identifying abnormalities in fetal development. Secondary prevention measures are aimed at preventing acute bronchopulmonary pathology and chronization of the process. Patients with lung agenesis are subject to medical examination, need vaccination against influenza and other respiratory infections, should be rationally employed.