Allergic alveolitis - Clinicals, Diagnosis, and Management

Pulmonology

Clinicals - History

Fact Explanation
Exposure to allergens This condition is triggered by exposure to various extrinsic substances. These substances cause type 1 and 3 hypersensitivity reactions in the distal bronchioles and alveoli which give rise to various symptoms. Some of these substances are misting fountains, yeast, pigeon antigens , spores of fungi and actinomycetes. and wood dust. Exposure to allergens
This condition is triggered by exposure to various extrinsic substances. These substances cause type 1 and 3 hypersensitivity reactions in the distal bronchioles and alveoli which give rise to various symptoms. Some of these substances are misting fountains, yeast, pigeon antigens , spores of fungi and actinomycetes. and wood dust.
Presentation This could be acute, subacute and chronic. Fever, chills, headaches, coughing, shortness of breath may be the acute presentation. Acute and subacute stages, mainly affect the lower parts of the lungs and chronic variety mainly the mid to upper parts of lungs. Same presentation as in acute stage with the less severity is seen in subacute type and fibrosis of the lung is the characteristic feature in late stages. Presentation
This could be acute, subacute and chronic. Fever, chills, headaches, coughing, shortness of breath may be the acute presentation. Acute and subacute stages, mainly affect the lower parts of the lungs and chronic variety mainly the mid to upper parts of lungs. Same presentation as in acute stage with the less severity is seen in subacute type and fibrosis of the lung is the characteristic feature in late stages.
Shortness of breath Usually develops after few hours of exposure. May be due to hypersensitivity pneumonitis. Shortness of breath
Usually develops after few hours of exposure. May be due to hypersensitivity pneumonitis.
Fever This may be one of the earliest symptoms which can develop even within few hours of exposure. Allergens trigger a hypersensitivity reaction in the lung, causing inflammation that releases pyrogens to cause fever. Fever
This may be one of the earliest symptoms which can develop even within few hours of exposure. Allergens trigger a hypersensitivity reaction in the lung, causing inflammation that releases pyrogens to cause fever.
Cough Cough is also a common clinical feature in these patients. There will be mechanical irritation of the receptors in the bronchial wall due to the extrinsic allergens. Cough
Cough is also a common clinical feature in these patients. There will be mechanical irritation of the receptors in the bronchial wall due to the extrinsic allergens.
History of asthma People who had a past history of asthma tend to get affected by the extrinsic allergens causing allergic alveolitis. History of asthma
People who had a past history of asthma tend to get affected by the extrinsic allergens causing allergic alveolitis.
Ankle swelling Allergic alveolitis can result in hypoxia. and if prolonged it can cause chronic hypoxia leading to right heart failure. Ankle swelling
Allergic alveolitis can result in hypoxia. and if prolonged it can cause chronic hypoxia leading to right heart failure.

Clinicals - Examination

Fact Explanation
Febrile Fever may be an earliest finding associated with the respiratory symptoms. Febrile
Fever may be an earliest finding associated with the respiratory symptoms.
Tachypnea This may be due to hypoxia, pneumonitis, or airway obstruction. Tachypnea
This may be due to hypoxia, pneumonitis, or airway obstruction.
Dyspnoea Dyspnoea is a frequent finding After exposure There can be an acute asthmatic reaction and may be due to hypersensitivity pneumonitis and develops even after few hours of exposure. Dyspnoea
Dyspnoea is a frequent finding After exposure There can be an acute asthmatic reaction and may be due to hypersensitivity pneumonitis and develops even after few hours of exposure.
Clubbing Lung fibrosis occurs in chronic disease and clubbing may be a feature of chronic disease. Clubbing
Lung fibrosis occurs in chronic disease and clubbing may be a feature of chronic disease.
Features of lung fibrosis (reduced chest expansion, increased vocal fremitus, dull percussion note, reduced breath sounds and coarse crepitations) During the pathogenesis of allergic alveolitis, there is hypersensitivity pneumonitis associated with the immune mechanisms, notably the involvement of CD8+ T lymphocytes. Ultimate result of all these is to cause interstitial fibrosis which can give the signs of consolidation. Features of lung fibrosis (reduced chest expansion, increased vocal fremitus, dull percussion note, reduced breath sounds and coarse crepitations)
During the pathogenesis of allergic alveolitis, there is hypersensitivity pneumonitis associated with the immune mechanisms, notably the involvement of CD8+ T lymphocytes. Ultimate result of all these is to cause interstitial fibrosis which can give the signs of consolidation.
Features of right heart failure(ankle and sacreal oedema, elevated jugular venous pressure) Hypoxia causes right heart failure. Features of right heart failure(ankle and sacreal oedema, elevated jugular venous pressure)
Hypoxia causes right heart failure.

Investigations - Diagnosis

Fact Explanation
Chest X-ray Reticular or nodular patterns is seen. This can be used to exclude the other conditions which may have the same presentation. Chest X-ray
Reticular or nodular patterns is seen. This can be used to exclude the other conditions which may have the same presentation.
HHigh resolution computed tomography (HRCT) This is one of the best investigations available. There will be opacities in the acute stage with ground-glass appearance and air trapping in the subacute stage. In the chronic stage there will be fibrosis and honeycombing of the lung. HHigh resolution computed tomography (HRCT)
This is one of the best investigations available. There will be opacities in the acute stage with ground-glass appearance and air trapping in the subacute stage. In the chronic stage there will be fibrosis and honeycombing of the lung.
Lung function tests Restrictive pattern is seen. Both vital capacity and forced expiratory volume in first second is reduced in these patients. Lung function tests
Restrictive pattern is seen. Both vital capacity and forced expiratory volume in first second is reduced in these patients.
Diffusing lung capacity Reduction of diffusing lung capacity in these patients and will be a marker of prognosis. Diffusing lung capacity
Reduction of diffusing lung capacity in these patients and will be a marker of prognosis.
IgG antibodies Antibodies to specific extrinsic allergen are found in the serum and sometimes in alveolar fluid via bronchoalveolar lavage. But on some occasions patients with the disease may have negative results. IgG antibodies
Antibodies to specific extrinsic allergen are found in the serum and sometimes in alveolar fluid via bronchoalveolar lavage. But on some occasions patients with the disease may have negative results.
Lung biopsy If there is any doubt about the diagnosis, a lung biopsy can be done and will reveal lymphohistiocytic patterns, bronchiolitis, and granulomas. Usually these patients have collections of CD8+ T lymphocytes in their airways. This will usually confirms the diagnosis. Lung biopsy
If there is any doubt about the diagnosis, a lung biopsy can be done and will reveal lymphohistiocytic patterns, bronchiolitis, and granulomas. Usually these patients have collections of CD8+ T lymphocytes in their airways. This will usually confirms the diagnosis.
Bronchoalveolar lavage There is alveolitis, which can give rise to lymphocytic or neutrophilic infiltration. Sometimes there will be moderate neutrophilia, and eosinophilia in the alveolar fluid. High neutrophil count in the bronchoalveolar fluid will be a n adverse prognostic factor. Bronchoalveolar lavage
There is alveolitis, which can give rise to lymphocytic or neutrophilic infiltration. Sometimes there will be moderate neutrophilia, and eosinophilia in the alveolar fluid. High neutrophil count in the bronchoalveolar fluid will be a n adverse prognostic factor.
Full blood count This will show leucocytosis. Full blood count
This will show leucocytosis.
Erythrocyte sedimentation rate (ESR)/ C Reactive protein(CRP) As there is an inflammation of the alveoli ESR and CRP can be elevated. Erythrocyte sedimentation rate (ESR)/ C Reactive protein(CRP)
As there is an inflammation of the alveoli ESR and CRP can be elevated.

Investigations - Management

Fact Explanation
Lung function tests Restrictive pattern is seen in lung functions and may be improving as the patient is avoiding the allergens. Lung function tests
Restrictive pattern is seen in lung functions and may be improving as the patient is avoiding the allergens.
IgG antibodies The level of antibodies to specific allergens may be elevated in these patients which usually decrease as the condition is improving. IgG antibodies
The level of antibodies to specific allergens may be elevated in these patients which usually decrease as the condition is improving.
Full blood count Patient may be having anaemia and low haemoglobin level in chronic lung diseases. Full blood count
Patient may be having anaemia and low haemoglobin level in chronic lung diseases.
Pulse oximetry They can develop hypoxia due to the pneumonitis and airway obstruction. Pulse oximetry
They can develop hypoxia due to the pneumonitis and airway obstruction.
High resolution computer tomography This is the best method to evaluate the conditions like interstitial fibrosis. High resolution computer tomography
This is the best method to evaluate the conditions like interstitial fibrosis.

Management - Supportive

Fact Explanation
Prevention of exposure This is the best management option available. This will reduce the disease progression and further episodes. Prevention of exposure
This is the best management option available. This will reduce the disease progression and further episodes.
Management of complications Patient may be presenting with hypoxia during an acute attack, which may require oxygen therapy. Management of complications
Patient may be presenting with hypoxia during an acute attack, which may require oxygen therapy.

Management - Specific

Fact Explanation
Early diagnosis This is the key for proper management and prevent the progression of disease. Early diagnosis
This is the key for proper management and prevent the progression of disease.
Steroid therapy Corticosteroids can be used for the treatment of allergic alveolitis. It is used in acute, subacute and chronic diseases, sometimes it is used for the long-term treatment of chronic disease. During the acute form 2-3 weeks of treatment may be sufficient, but chronic form may require much higher doses. Clinical symptoms, and lung functions are usually improved with the treatment and should not be used for long-term, if there is no clinical improvement. Long term course of corticosteroids can lead to side effects and measures should be taken to minimize them. Side effects would be cushingoid features (moon face, increased fat deposition over the back of the neck, truncal obesity), diabetes, hypertension and osteoporosis. Steroid therapy
Corticosteroids can be used for the treatment of allergic alveolitis. It is used in acute, subacute and chronic diseases, sometimes it is used for the long-term treatment of chronic disease. During the acute form 2-3 weeks of treatment may be sufficient, but chronic form may require much higher doses. Clinical symptoms, and lung functions are usually improved with the treatment and should not be used for long-term, if there is no clinical improvement. Long term course of corticosteroids can lead to side effects and measures should be taken to minimize them. Side effects would be cushingoid features (moon face, increased fat deposition over the back of the neck, truncal obesity), diabetes, hypertension and osteoporosis.

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