Lung B/35 Bronchial asthma and emphysema Flashcards
Characteristic FVC and FEV1 values for bronchial asthma
FVC: Forced Vital Capacity, it is normal in asthma
FEV1: is decreased
FEV1/FVC is decreased
The two main forms of bronchial asthma?
What are they mediated by in the acute phase
Intrinsic and Extrinsic
Aka
Non-Atopic and Atopic
Extrinsic:
Allergen provokes a TH2 mediated cytokine response. IL4- induces IgE, IL5- activates eosinophils, IL13- mucus production.
Mast cells and eosinophils degranulate Histamine, Prostaglandins, ACh, and leukotrienes and promote bronchospasm
IgE are produced excessively by B cells.
There is family history, and serum IgE is elevated
Intrinsic:
No associated allegries, and IgE levels are normal.
There is hyper-responsive bronchial epithelium.
Asthma attacks are provoked by inhaled pollutants and viral infections.
Both:
The bronchospasm is mediated by eiosinophil and mast cell degranulation and inflammatory mediators provoking bronchospasm, subsequent tissue damage and fibrosis
How is asthma treated?
with bronchodilators (beta2R agonists) and corticosteroids
Clinical presentation of bronchial asthma?
Histological presentation?
Severe dyspnea, wheezing, especially at night. Reversible with bronchodilators..
Attacks usually last about an hour.
Status Asthmaticus: refractory asthma attack that lasts for several days, can be fatal.
Histology: “Airway Remodelling” occurs in chronic asthma:
Chronic bronchial inflammation.
Eosinophil infiltration.
Smooth muscle hypertrophy. Mucus gland hypertrophy.
Increased mucus secretions.
Increased collagen deposition and lung fibrosis
Thickened walls of airways
Goblet cell metaplasia
Mucous plugs containing CURSCHMANN SPIRALS,
and
CHARCOT-LEYDEN CRYSTALS.
Curschmann Spirals of thick mucous with dark, basophilic whorls of shed epithelial cells.
Charcot-Leyden crystals of crystallized eosinophilic proteins from eosinophil granules.
Potential genes invovled in asthma
HLA alleles
IL-13
IL-4 receptors
Diagnosing atopic vs non-atopic asthma
Atopic asthma
Allergen skin test and positive DHT reaction for the allergen.
Serology for IgEs against allergens
Non-Atopic
negative skin tests
Sputum containing curschmann spirals and charcot leyden crystals is diagnositc for asthma of both types.
What are the other forms of asthma besides the two major ones?
Drug induced asthma - Aspirin is the most common culprit. COX inhibition without LOX inhibition somehow shifts the lung balance to promote bronchospasm.
Occupational astham –> acquired atopic asthma after repeated exposure to the occupational antigen of dust or plastic.
What are the types of emphysema?
Centriacinar / centrilobular
Panacinar / panlobular
Distal acinar / paraseptal
Irregular
Describe the most common type of emphysema
Centriacinar aka centrilobular
The most central/proximal part of the respiratory bronchiole is most dilated, while the distal alvioli are normal.
Caused primarily by smoking.
Affects the Upper lobes most strongly (just think that smoke rises and affects the top lobes first)
Histologically: destruction of alveolar septa, and central dilation WITHOUT FIBROSIS OF THE REMAINING ALVEOLAR SEPTA.
There IS FIBROSIS of the BRONCHIOLES in advanced emphysema.
LOSS OF ELASTIC TISSUE that would be in the septa.
This causes ALVEOLAR COLLAPSE that is part of the obstruction in severe emphysema/COPD.
Describe the second most common type of emphysema
Panacinar or panlobular emphnysema
The entire alveolus and resp. bronchiole is dilated.
Occurs from an alpha1-antitrypsin deficiency.
Occurs more in the lower lobes than apical.
Describe distal acinar emphysema
Distal acinar aka Paraseptal emphysema
The proximal resp. bronchiole is normal, but the distal alvolar walls are dilated.
This occurs mostly at the lung BORDERS, of the PLEURA and FIBROUS SEPTA.
This type of Emphysema forms the BULLAE, which can rupture and invoke spontaneous PTX.
Describe irregular emphysema
Dilation of no consistent pattern.
Associated with scarred regions that have healed after an inflammatory lesion.
Describe senile emphysema
This is observed on the gross lung specimen, where the mediastinal regions of the lung are most emphysemic, as these regions are the ones subjected to the largest amount of movement and stretching during ventilation, so over time they become the most damaged.
Describe mediastinal emphysema
The crazy kind where there is a rupture of the lung tissue leading to air flowing into the connective tissue of the lung parenchyma.
Can be seen in whooping cough or extreme vomitting/coughing fits due to very high increased alveolar pressure.
Air forced into the lung parenchyma and then into the body of the patient, causing marked swelling of the head and neck due to air in the subcutaneous tissue.
