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Asbestos Poisoning: Causes, Symptoms and Treatment
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Chapters
0:00 Introduction
0:46 Causes of Asbestos Poisoning
1:24 Symptoms of Asbestos Poisoning
2:01 Treatment for Asbestos Poisoning
Asbestosis is long-term inflammation and scarring of the lungs due to asbestos fibers.[4] Symptoms may include shortness of breath, cough, wheezing, and chest tightness.[1] Complications may include lung cancer, mesothelioma, and pulmonary heart disease.[1][2]
Asbestosis is caused by breathing in asbestos fibers. It requires a relatively large exposure over a long period of time, which typically only occur in those who directly work with asbestos.[1][2] All types of asbestos fibers are associated with an increased risk.[9] It is generally recommended that currently existing and undamaged asbestos be left undisturbed.[10] Diagnosis is based upon a history of exposure together with medical imaging.[4] Asbestosis is a type of interstitial pulmonary fibrosis.[4]
There is no specific treatment.[1] Recommendations may include influenza vaccination, pneumococcal vaccination, oxygen therapy, and stopping smoking.[5] Asbestosis affected about 157,000 people and resulted in 3,600 deaths in 2015.[8][7] Asbestos use has been banned in a number of countries in an effort to prevent disease.[1]
Statistics from the Health and Safety Executive showed that in 2019, there were 490 asbestosis deaths.[11]
The signs and symptoms of asbestosis typically manifest after a significant amount of time has passed following asbestos exposure, often several decades under current conditions in the US.[12] The primary symptom of asbestosis is generally the slow onset of shortness of breath, especially with physical activity.[13] Clinically advanced cases of asbestosis may lead to respiratory failure. When a stethoscope is used to listen to the lungs of a person with asbestosis, they may hear inspiratory "crackles".
The characteristic pulmonary function finding in asbestosis is a restrictive ventilatory defect.[14] This manifests as a reduction in lung volumes, particularly the vital capacity (VC) and total lung capacity (TLC). The TLC may be reduced through alveolar wall thickening; however, this is not always the case.[15] Large airway function, as reflected by FEV1/FVC, is generally well preserved.[12] In severe cases, the drastic reduction in lung function due to the stiffening of the lungs and reduced TLC may induce right-sided heart failure (cor pulmonale).[16][17] In addition to a restrictive defect, asbestosis may produce reduction in diffusion capacity and a low amount of oxygen in the blood of the arteries.
Cause
White asbestos fibers identified in room air analysis, magnified 5000 times using a scanning electron microscope
The cause of asbestosis is the inhalation of microscopic asbestos mineral fibers suspended in the air.[18] In the 1930s, E. R. A. Merewether found that greater exposure resulted in greater risk.[19]
Pathogenesis
Asbestosis is the scarring of lung tissue (beginning around terminal bronchioles and alveolar ducts and extending into the alveolar walls) resulting from the inhalation of asbestos fibers. There are two types of fibers: amphibole (thin and straight) and serpentine (curly). All forms of asbestos fibers are responsible for human disease as they are able to penetrate deeply into the lungs. When such fibers reach the alveoli (air sacs) in the lung, where oxygen is transferred into the blood, the foreign bodies (asbestos fibers) cause the activation of the lungs' local immune system and provoke an inflammatory reaction dominated by lung macrophages that respond to chemotactic factors activated by the fibers.[20] This inflammatory reaction can be described as chronic rather than acute, with a slow ongoing progression of the immune system attempting to eliminate the foreign fibers.
Due to the asbestos fibers' natural resistance to digestion, some macrophages are killed and others release inflammatory chemical signals, attracting further lung macrophages and fibrolastic cells that synthesize fibrous scar tissue, which eventually becomes diffuse and can progress in heavily exposed individuals. This tissue can be seen microscopically soon after exposure in animal models. Some asbestos fibers become layered by an iron-containing proteinaceous material (ferruginous body) in cases of heavy exposure where about 10% of the fibers become coated. Most inhaled asbestos fibers remain uncoated. About 20% of the inhaled fibers are transported by cytoskeletal components of the alveolar epithelium to the interstitial compartment of the lung where they interact with macrophages and mesenchymal cells. The cytokines, transforming growth factor beta and tumor necrosis factor alpha, appear to play major roles in the development of scarring inasmuch as the process can be blocked in animal models by preventing the expression of the growth factors.[21][22] The result is fibrosis in the interstitial space, thus asbestosis.
Chapters
0:00 Introduction
0:46 Causes of Asbestos Poisoning
1:24 Symptoms of Asbestos Poisoning
2:01 Treatment for Asbestos Poisoning
Asbestosis is long-term inflammation and scarring of the lungs due to asbestos fibers.[4] Symptoms may include shortness of breath, cough, wheezing, and chest tightness.[1] Complications may include lung cancer, mesothelioma, and pulmonary heart disease.[1][2]
Asbestosis is caused by breathing in asbestos fibers. It requires a relatively large exposure over a long period of time, which typically only occur in those who directly work with asbestos.[1][2] All types of asbestos fibers are associated with an increased risk.[9] It is generally recommended that currently existing and undamaged asbestos be left undisturbed.[10] Diagnosis is based upon a history of exposure together with medical imaging.[4] Asbestosis is a type of interstitial pulmonary fibrosis.[4]
There is no specific treatment.[1] Recommendations may include influenza vaccination, pneumococcal vaccination, oxygen therapy, and stopping smoking.[5] Asbestosis affected about 157,000 people and resulted in 3,600 deaths in 2015.[8][7] Asbestos use has been banned in a number of countries in an effort to prevent disease.[1]
Statistics from the Health and Safety Executive showed that in 2019, there were 490 asbestosis deaths.[11]
The signs and symptoms of asbestosis typically manifest after a significant amount of time has passed following asbestos exposure, often several decades under current conditions in the US.[12] The primary symptom of asbestosis is generally the slow onset of shortness of breath, especially with physical activity.[13] Clinically advanced cases of asbestosis may lead to respiratory failure. When a stethoscope is used to listen to the lungs of a person with asbestosis, they may hear inspiratory "crackles".
The characteristic pulmonary function finding in asbestosis is a restrictive ventilatory defect.[14] This manifests as a reduction in lung volumes, particularly the vital capacity (VC) and total lung capacity (TLC). The TLC may be reduced through alveolar wall thickening; however, this is not always the case.[15] Large airway function, as reflected by FEV1/FVC, is generally well preserved.[12] In severe cases, the drastic reduction in lung function due to the stiffening of the lungs and reduced TLC may induce right-sided heart failure (cor pulmonale).[16][17] In addition to a restrictive defect, asbestosis may produce reduction in diffusion capacity and a low amount of oxygen in the blood of the arteries.
Cause
White asbestos fibers identified in room air analysis, magnified 5000 times using a scanning electron microscope
The cause of asbestosis is the inhalation of microscopic asbestos mineral fibers suspended in the air.[18] In the 1930s, E. R. A. Merewether found that greater exposure resulted in greater risk.[19]
Pathogenesis
Asbestosis is the scarring of lung tissue (beginning around terminal bronchioles and alveolar ducts and extending into the alveolar walls) resulting from the inhalation of asbestos fibers. There are two types of fibers: amphibole (thin and straight) and serpentine (curly). All forms of asbestos fibers are responsible for human disease as they are able to penetrate deeply into the lungs. When such fibers reach the alveoli (air sacs) in the lung, where oxygen is transferred into the blood, the foreign bodies (asbestos fibers) cause the activation of the lungs' local immune system and provoke an inflammatory reaction dominated by lung macrophages that respond to chemotactic factors activated by the fibers.[20] This inflammatory reaction can be described as chronic rather than acute, with a slow ongoing progression of the immune system attempting to eliminate the foreign fibers.
Due to the asbestos fibers' natural resistance to digestion, some macrophages are killed and others release inflammatory chemical signals, attracting further lung macrophages and fibrolastic cells that synthesize fibrous scar tissue, which eventually becomes diffuse and can progress in heavily exposed individuals. This tissue can be seen microscopically soon after exposure in animal models. Some asbestos fibers become layered by an iron-containing proteinaceous material (ferruginous body) in cases of heavy exposure where about 10% of the fibers become coated. Most inhaled asbestos fibers remain uncoated. About 20% of the inhaled fibers are transported by cytoskeletal components of the alveolar epithelium to the interstitial compartment of the lung where they interact with macrophages and mesenchymal cells. The cytokines, transforming growth factor beta and tumor necrosis factor alpha, appear to play major roles in the development of scarring inasmuch as the process can be blocked in animal models by preventing the expression of the growth factors.[21][22] The result is fibrosis in the interstitial space, thus asbestosis.
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