*Obstructive Airway Disease Flashcards
What is obstructive airway disease?
Any respiratory disease characterised by air trapping caused by either decrease airway diameter or increased airway secretions, or both
what are 3 obstructive airway disease?
Asthma
Chronic bronchitis
Emphysema
What is asthma/ COPD overlap syndrome?
Not clearly defined but patients with features of asthma and COPD (e.g. atopic smoker with partially reversible airway obstruction) - COPD with reversibility and eosinophilia who are steroid responsivE
What causes the turbulent airflow in asthma and COPD?
Mucosa and sub-mucosa become inflamed and invaginate and therefore obstruct airflow
what type of leukocytes are involved in COPD and asthma?
COPD = neutrophil Asthma = eosinophil
How can the tone of the smooth muscle be described in COPD and asthma?
COPD = hypertrophic Asthma = twitchy
What 3 sets of words can be used to describe asthma?
Early onset/ late onset
Atopic (allergic)/ non-atopic
Extrinsic (external factor)/ intrinsic (internal factor)
What is the asthma triad?
Airway inflammation Reversible airflow obstruction Airway hyperresponsivenes (hyperreactivity)
What is the evolution of asthma?
Bronchoconstriction (brief symtpoms) Chronic airway inflammation (exacerbations airway hyperresponsiveness) Airway remodelling (fixed airway obstruction = COPD like symptoms)
What are the hallmarks of asthma remodelling? (3)
Basement membrane = thickened
Submucosa = collagen deposition
Smooth muscle = hypertrophy
What is the inflammatory cascade in asthma? + treatment?
Genetic predisposition + triggers (viruses, allergen, chemical, nutrition) - avoidance
Eosinophilic inflammation - anti-inflamatory (corticosteroid)
TH2 cells release mediators (Interleukins e.g. IL-12, IL-4, IL-5) - anti-leukotriene/ histamine, anti-IgE, anti-IL5)
Twitchy smooth muscle (hyper-reactivity) - bronchodilators (beta-2 agonists, muscarinic antagonists)
What are examples of the environmental factors that can affect asthma?
Genetic factors?
Age, gender, obesity, infeciton, atopic status, allergin exposure
Genetic = Epithelial-specific asthma gene signature
Examples of some asthma triggers?
Animal dander Dust mites Pollens Fungi Exercise Viral infection Smoke Cold Chemicals drugs (NSAIDs, beta-blockers)
What are the clinical signs of asthma?
Episodic symptoms and signs diurnal variability (nocturnal/ early morning) non-productive cough, wheeze triggers assocaited atopy family history
What can be used to help diagnose asthma?
History and examination
diurnal variation of peak flow rate
Reduced forced expiator rate (FEV1/FVC 15%)
Provocation testing leads to bronchospasm
What can be used to provoke asthma in the clinical setting?
Exercise
Histamine/ metacholine/ mannitol
What are the 3 components of COPD caused by noxious particles or gases?
Mucociliary dysfunction
Neutrophilic inflammation
Tissue damage
(these lead to the development of obstruction and ongoing disease progression)
What are the characteristics of COPD? (2)
Exacerbations
Reduced lung fucntion
What is the disease process in COPD?
Inhaled noxious chemicals causes inflammation of the lungs (if normal protective mechanisms aren’t working properly)
Cigarette smoke activated macrophages and airway epithelial cells which release neutrophili chemotaxis factor
Neutrophils and macrophages then releases proteases that break down lung parenchyma (emphysema)and stimulate mucous hyper secretion (chronic bronchitis)
Cytotoxic T cells may also be involved
In COPD, what is there an imbalance of?
Proteases and anti-proteases (e.g. alpha1-antitrypsin)
What are the features of chronic bronchitis?
Chronic neutrophilic inflamation mucus hypersecretion mucociliary dysfunction altered lung biome smooth muscle spasm and hypertrophy Partially reversible
What are the features of emphysema?
Alveolar destruction
Impaired gas exchange
Loss of bronchial support
Irreversible
What are indicative of high risk COPD?
2 exacerbations or more within the past year or FEV2 less than 50%
Clinical features of COPD?
Chronic symptoms (not episodic) Smoking Non-atopic Daily productive cough Progressive breathlessness Frequent infective exacerbations Chronic bronchitis = wheezing Emphysema = reduced breath sounds
