Respiratory conditions Flashcards
What are examples of obstructive airway disease?
Asthma, chronic bronchitis and emphysema, (COPD).
What is ACOS?
ACOS is asthma/COPD overlap syndrome, patients with features of both COPD and asthma, e.g. COPD with reversibility and eosinophilia who are steroid responsive.
What is asthma?
Asthma is a chronic inflammatory disease of the airways.
What is the asthma triad?
The asthma triad is reversible airflow obstruction, airway hyper-responsiveness and airway inflammation.
What are the hallmarks of remodeling in asthma?
Thickening of the basement membrane, collagen deposition in the submucosa, and hypertrophy of smooth muscle.
Describe the inflammatory cascade in asthma.
A genetic predisposition to asthma and the presence of triggers causes eosinophilic inflammation. Eosinophils release inflammatory mediators in the form of TH2 cytokines. TH2 cytokines cause hyper-reactivity of airway smooth muscle.
How can a genetic predisposition to triggers of asthma be treated?
Avoidance of those triggers, e.g. allergens.
How can eosinophilic inflammation of asthma be treated?
Anti-inflammatory drugs, e.g. corticosteroids or cromones.
How can inflammatory mediators and TH2 cytokines in asthma be treated?
Anti-leukotrienes/histamine, anti-IgE and anti-IL5.
How can hyper-reactivity of asthma be treated?
By bronchodilators, e.g. beta-2-agonists or muscarinic antagonists.
What may inflammation in asthma show on photomicrographs?
Desquamation of airway epithelium, numerous eosinophils, thickening of basement membrane.
What signs and symptoms may point to a diagnosis of asthma?
Episodic symptoms, diurnal variability (worse at night and early morning), non-productive cough, or wheeze due to turbulent airflow. Patient may also experience symptoms in response to triggers, have associated atopy or a FHx of asthma.
What is the forced expiratory ratio in asthma?
Asthmatics have a reduced forced expiratory ratio of <75%, but experience >15% reversibility in response to salbutamol.
How may a diagnosis of asthma be made?
Provocation testing leading to bronchospasm, by exercise or exposure to histamine/methacholine/mannitol.
What are the main components of COPD?
COPD is a multicomponent disease process consisting of: mucociliary dysfunction, inflammation and tissue damage/
What are the characteristics and symptoms of COPD?
A patient experiences frequent exacerbations, reduced lung function. They become increasingly breathless and have a worsening quality of life due to obstruction and disease progression.
What are the triggers and pathophysiology of COPD?
Exposure to inhaled noxious particles or gases causes lung inflammation which may lead to COPD if normal protective/repair mechanisms are defective.
Irritants activate macrophages and airway epithelial cells to release neutrophil cytokines, IL-8 and LTB4. Neutrophils and macrophages release proteases to break down connective tissues in lung parenchyma (alveolar wall destruction–> emphysema) and stimulate mucus hypersecretion (chronic bronchitis).
How may mucociliary function be compromised?
Mucociliary function may be compromised by damage to the cilia due to enzymes, e.g. neutrophil elastase, attracted to airways by toxins.
COPD patients have recurrent resp. tract infection, how may this damage the respiratory mucosa?
Commonly H. influenza, which may break down epithelial cell walls, leading to loss of ciliated cells and damaging airway tissue.
Why does emphysema occur?
Alveolar destruction, causes increased air spaces. Due to proteases, e.g. neutrophil elastase, and may relate to an imbalance of proteases and anti-proteases.
Give 4 features of chronic bronchitis.
- Chronic neutrophilic inflammation.
- Mucus hypersecretion.
- Mucociliary dysfunction.
- Altered lung microbiome.
- Smooth muscle spasm and hypertrophy.
- Partially reversible.
Give the features of emphysema.
- Alveolar destruction.
- Impaired gas exchange.
- Loss of bronchial support.
- Irreversible.
What are indicators of high risk COPD?
2 or more exacerbations within the past year, or an FEV1 <50% of predicted.
What are the signs and symptoms of COPD?
Chronic symptoms, smoker, non-atopic, a daily productive cough, progressive breathlessness, frequent infective exacerbations.
Chronic bronchitis: wheezing.
Emphysema: reduced breath sounds.