L7 18 Mar 2019 Flashcards
Asthma
What are the three types of chronic obstructive pulmonary disease?
- emphysema: alveolar wall destruction, over inflation
- chronic bronchitis: productive cough, airway inflammation
- asthma: reversible obstruction
emphysema
- irreversible enlargement of airspaces, distal to terminal bronchiole
- most smokers suffer from this
- too much coughing –> elasticity is lost, also tar deposit
chronic bronchitis
- persistent cough with sputum production for at least 3 mths in two consecutive years; may progress to COPD and may overlap with emphysema –> hypersecretion of mucus and if persistene marked increase in goblet cells in small airways
- therapy: mucolytics
asthma
- chronic disorder of airways, usually caused by immunological reaction, marked by bronchoconstriction
- increased airway sensitivity to various stimuli
- inflammation of bronchial walls
- increased mucus secretion
- bronchial hyperresponsiveness
symptoms of asthma
- recurrent episodes of wheezing
- breathlessness
- chest tightness
- dry cough
four types of asthma
- atopic asthma
- non-atopic asthma
- drug-induced asthma
- occupational asthma
atopic asthma
- triggered by environmental allergens (dusts, pollens, roach or animal dander, foods)
- type I IgEmediated hypersensitivity reaction
- hereditary, and also common type of asthma
non-atopic asthma
typically virus-induced inflammation lowers threshold to irritants
drug-induced asthma
salicylate (aspirin)-induced is a typical example
occupational asthma
exposure to fumes (plastics, organic solvents, chemical dusts)
common precipitating factors in aetiology of asthma
- common cold/other viral infections, sinusitis, bronchitis/bronchiolitis
- pollens (weeds, grasses, trees), dusts, feathers, animal fur, furniture stuffing, fungal spores
- fumes (petrol, paint, tobacco, industrial chemicals), cold air, air pollutants
- laughter, physical exertion, psychological stress, drugs
how is asthma diagnosed?
- perisistent cough
- wheezing (via stethoscope)
- shortness of breath - stethoscope
- spirometry - most common lung function test
complication of diagnosis(/misdiagnosis) with asthma
- anaphylaxis: need epinephrine
- pulmonary embolism: need blood thinning - warfarin
spirometry
measures FEV (forced expiratory volume)
- not safe to do spirometry with methacoline and exercise challenges
pathologenesis of atopic asthma
Type I IgE-mediated hypersensitivity immediate reaction
- alleren stimulates TH2 response
- class switching from IgG (B cells) to IgE
- IgE binds to Fc receptors on mast cells
- subsequent exposure to allergen = mast cell activation
atopic asthma pathologenesis
mast cell mediators
- ECF: eosinophil chemotactic factor
- NCF: neutrophil chemotactic factor
- PAF: platelet activating factor
late phase reaction = chemotactic factors + leukotrines
pathology of atopic asthma
- thickened basement membrane
- increase mucous in bronchial lumen
- goblet cell hyperplasia
- hypertrophyof submucosal glands
- hypertrophy/hyperplasia of smooth muscle
clinical features of allergic asthma
- family history usually positive
- attacks related to specific antigens
- history of eczema in childhood
- IgE associated
- skin test results usually positive
clinical features of nonallergic asthma
- family history usually negative
- attacks related to infections, exercise and other stimuli
- skin test usually negative
- no history of eczema in childhood
- not IgE associated
- consider occupational asthma as a cause
management of asthma
- majority of cases:
- short acting β2-agonist: bronchodilation
- low-dose inhaled corticosteroid: broad spectrum anti-inflammatory response
- therapy adapted with severity of disease
