Idiopathic pulmonary fibrosis is a pathological process based on extensive lesion of interstitial lung tissue, leading to the development of fibrous changes and respiratory failure. The progression of disease is accompanied by a steady increase in weakness, weight loss, shortness of breath, unproductive cough, chest pain, cyanosis. Diagnosis is based on the data of radiography and computed tomography of the lungs, spirometry, lung biopsy. Treatment includes anti-inflammatory and immunosuppressive therapy, oxygen therapy; according to the indications – lung transplantation.
ICD 10
J84.1 Other interstitial pulmonary diseases with mention of fibrosis
Meaning
Idiopathic pulmonary fibrosis (fibrosing alveolitis, Hammen-Rich syndrome) is a progressive diffuse bilateral lesion of the alveoli and interstitial lung tissue, accompanied by the development of diffuse fibrosis and increasing respiratory failure. Disease has an exclusively pulmonary localization, does not respond well to therapy, and often ends in death.
Fibrosing alveolitis is a relatively rare disease of unclear etiology, but it tends to increase. Pathology more often affects men older than 50 years (20 cases out of 100 thousand) than women (13 cases out of 100 thousand). Mortality in fibrosing alveolitis reaches 3.3 cases per 100 thousand population.
Causes of idiopathic pulmonary fibrosis
The causes of fibrosing alveolitis are unclear. There are assumptions about the autoimmune nature of the disease, viral nature (herpesvirus, hepatitis C virus, adenoviruses, cytomegalovirus), hereditary predisposition.
In the prevalence of fibrosing alveolitis, professional, environmental, household and geographical factors are important. Thus, it has been noted that the development of idiopathic fibrosing alveolitis is most susceptible to farmers raising birds, workers in contact with wood, asbestos, metal and silicate dust, smoking patients.
Pathogenesis
Inflammatory phenomena in the alveoli cause irreversible thickening of their walls and a decrease in permeability for gas exchange. The development of idiopathic fibrosing alveolitis is characterized by three interrelated processes: interstitial edema, interstitial inflammation (alveolitis) and interstitial fibrosis.
In the acute stage of interstitial edema, alveolar capillaries and epithelium are affected, their edema and the formation of hyaline membrane complexes that prevent the expansion of alveolar tissue during breathing. At this stage, regression of the process or the development of interstitial pneumonia is possible. The chronic stage of interstitial inflammation is characterized by further progression of the process, deposition of collagen in the alveoli and the development of widespread fibrosis with extensive damage to the lung tissue.
In the terminal stage of interstitial fibrosis, the capillary network and alveolar tissue are completely replaced by fibrous tissue with the formation of cavity extensions. The lung tissue resembles a honeycomb in appearance. Irreversible changes in the alveolar-capillary system of the lungs with fibrosing alveolitis lead to restrictive changes, gas exchange disorder, progression of respiratory failure and death of the patient.
Classification
In clinical pulmonology , there are 3 forms of fibrosing alveolites:
- Fibrosing idiopathic alveolitis. They include the following morphological forms: common interstitial pneumonia, desquamative interstitial pneumonia, acute interstitial pneumonia and nonspecific interstitial pneumonia.
- Alveolitis is exogenous allergic.Exogenous allergic alveolites include diseases caused by prolonged and intensive inhalation of dust containing animal and vegetable proteins or inorganic pollutants, and accompanied by diffuse allergic damage to interstitial and alveolar pulmonary structures (syndromes “farmer’s lung”, “poultry breeder’s lung”, “cheese maker’s lung”, “worker’s lung”, etc.).
- Fibrosing toxic alveolites. Fibrotic toxic alveolitis includes lung diseases resulting from the toxic effects of industrial, chemical substances and medicinal chemotherapeutics. Downstream, I distinguish acute, subacute and chronic fibrosing alveolitis.
Idiopathic pulmonary fibrosis symptoms
The development of the disease is gradual with the development of irreversible changes in the alveoli and a steady increase in shortness of breath. For a long time, patients do not attach importance to this and do not consult a doctor, explaining the changes in their well-being by fatigue at work, cessation of sports, weight gain, etc. It usually takes from 3 months to 1-3 years from the onset of the first symptoms of fibrosing alveolitis to treatment at a medical institution.
The leading complaints in fibrosing alveolitis are pronounced shortness of breath with minimal physical exertion and an unproductive cough. Patients are concerned about chest pains (under the shoulder blades) that prevent deep breathing, weight loss, weakness, muscle and joint pain, increased body temperature. In half of patients with fibrosing alveolitis, the nail phalanges acquire the characteristic appearance of “drumsticks” with “watch glasses”. Cyanosis and shortness of breath are resistant to therapy. In the future, there is an increase in hypoxemia, pulmonary hypertension and right ventricular failure.
Complications
In the terminal stage of fibrosing alveolitis, signs of respiratory failure and the development of the pulmonary heart disease increase: gray-ash diffuse cyanosis, swelling of the neck veins, edema, the development of cachexia. The course of fibrosing alveolitis causes progressive respiratory failure, the development of a pulmonary heart, and may be complicated by pulmonary edema.
Diagnostics of idiopathic pulmonary fibrosis
With fibrosing alveolitis in the lungs, hard breathing, crepitation (a symptom of “cellophane crackling”) is heard and dry wheezing; percussion sound is shortened. Changes on the part of the heart are characterized by tachycardia and muffled tones. Stages of diagnosis:
- Radiography. In lung x-ray, the picture of ideopathic fibrosing alveolitis corresponds to small-focal diffuse bilateral changes in the lungs, more pronounced in the lower parts, emphysema of the lungs. The late stage of fibrosing alveolitis corresponds to secondary cystic changes in the lungs (“cellular lung”). Dynamic radiography provides information about the irreversibility of changes characteristic of fibrosing alveolitis.
- Computed tomography. Allows you to identify changes in the lungs in the early stages. A characteristic feature of fibrosing alveolitis is the definition of a symptom of “frosted glass” – a gentle homogeneous darkening of the pulmonary fields. According to the CT of the lungs, it is possible to determine the site of the modified tissue for taking a lung biopsy.
- Functional diagnostics. Indicators of the function of external respiration (spirometry, peak flowmetry) in fibrosing alveolitis indicate ventilation disorders and a decrease in the diffuse ability of the lungs. ECG shows signs of hypertrophy and overload of the right parts of the heart.
- Blood test. Laboratory blood parameters are characterized by leukocytosis and acceleration of ESR, increased hemoglobin and hematocrit; increased levels of fibrin, sialic acids, immunoglobulins, determination of rheumatoid factor.
- Bronchoscopy. In fibrosing alveolitis, it is performed for the purpose of differential diagnosis with infectious or tumor processes in the lungs. In the lavage fluid obtained during bronchoscopy, an increase in total protein, immunoglobulins, macrophages with cytoplasmic inclusions, neutrophils is determined.
Conducting an open lung biopsy for fibrosing alveolitis allows you to determine the stage of the disease, the choice of appropriate treatment, and the development of the disease. During histological examination, five degrees of changes are distinguished:
- 1 – infiltration and thickening of the alveolar septa;
- 2 – filling of the lumen of the alveoli with exudate and cellular composition;
- 3 – destruction of the alveoli;
- 4 – complete change in the structure of lung tissue;
- 5 – formation of cystic-altered cavities.
Differential diagnosis
Fibrosing alveolitis should be differentiated with pneumonia, granulomatosis, sarcoidosis, disseminated tuberculosis, bronchioloalveolar cancer, pneumoconiosis, diffuse amyloidosis, etc.
Large and small diagnostic criteria for fibrosing alveolitis have been developed. Fibrosing alveolitis is most likely to be diagnosed by determining 4 large and 3 small criteria. The big criteria for the verification of ideopathic fibrosing alveolitis are:
- exclusion of other interstitial lung pathology, including toxic and allergic fibrotic alveolitis, systemic connective tissue diseases;
- characteristic violations of the function of external respiration
- the presence of bilateral changes in the lower parts of the lungs (symptoms of “frosted glass” and “cellular lung”);
- histological exclusion of other pulmonary pathology.
The small criteria of ideopathic fibrosing alveolitis include:
- the age of the patient is over 50 years old;
- gradual imperceptible increase in shortness of breath during physical exertion;
- the duration of the disease is more than 3 months;
- crepitation (crackling) when breathing in the lower parts of the lungs.
Idiopathic pulmonary fibrosis treatment
Non-drug therapy
The purpose of the treatment carried out by a pulmonologist is to alleviate the course of the disease, slow down the progression of pulmonary fibrosis, and improve the quality of life of the patient. Non-drug treatment of fibrosing alveolitis includes special rehabilitation programs, including physical training, psychological support for patients. Oxygen therapy has a pronounced therapeutic effect, reducing shortness of breath and increasing the endurance of physical exertion in patients with fibrosing alveolitis.
Pharmacotherapy
To achieve a state of remission, anti-inflammatory and antifibrotic drugs, immunosuppressants (azathioprine), as well as their combination are included in the drug therapy of fibrosing alveolitis. At the same time, veroshpiron, potassium preparations, pyridoxine, bronchodilators are prescribed. Drug therapy gives effect only in cases of absence of pronounced pneumofibrosis. In order to prevent viral infections, influenza and anti-pneumococcal vaccination is indicated for all patients with fibrosing alveolitis.
Radical treatment of fibrosing alveolitis involves lung transplantation, which gives a high percentage of 5-year survival – up to 50-60%. Indications for lung transplantation are pronounced hypoxemia, dyspnea, a decrease in the VCL below 70%, a decrease in the diffuse ability of the lungs.
Prognosis and prevention
During idiopathic fibrosing alveolitis, periods of remission are observed after drug therapy, but the disease still gradually progresses. The average survival rate in the diagnosis of untreated fibrosing alveolitis is 3-4 years. Allergic and toxic alveolitis differ in a more favorable course, which, when the provoking factor is eliminated in the early stages, can regress.
Measures for the prevention of idiopathic fibrosing alveolitis include the prevention of infections, the exclusion of harmful occupational, environmental and household factors. Patients with fibrosing alveolitis should be registered at the dispensary with a pulmonologist, allergist and a professional pathologist.
Literature
- Idiopathic pulmonary fibrosis: evolving concepts. Ryu JH, Moua T, Daniels CE, Hartman TE, Yi ES, Utz JP, Limper AH. Mayo Clin Proc. 2014 Aug;89(8):1130-42. link
- Usual interstitial pneumonia end-stage features from explants with radiologic and pathological correlations. Rabeyrin M, Thivolet F, Ferretti GR. 2015 Aug;19(4):269-76. link
- Idiopathic pulmonary fibrosis. Doubková M, Skhicková J. Vnitr Lek. 2005 Dec;51(12):1375-84. link
- Idiopathic pulmonary fibrosis. Cordier JF. Rev Prat. 2007 Dec 31;57(20):2227-34 link