Obstructive Airway Disease Flashcards
What area is affected by obstructive disease?
Airways
How many times does the airways bifurcate after the trachea bifurcation?
23
What is the conducting zone?
Conducting zone of the respiratory system is made up of the nose, pharynx, larynx, trachea, bronchi, bronchioles, and terminal bronchioles
What is the function of the conducting zone?
Filter, warm, and moisten air and conduct it into the lungs
What makes up the respiratory zone?
Respiratory bronchioles and the alveolar ducts
What is the function of the respiratory zone?
Exchanging of gases
Respiratory tract =
Conducting zone + Respiratory zone
What is happening in obstructive lung disease?
People find it hard to exhale of the air in their lungs due to obstruction
What is the main symptom that obstructive and restrictive lung disease share?
Shortness of breath with exertion
Obstructive airway syndrome (3 components):
1) Chronic bronchitis 2) Emphysema 3) Asthma (umbrella term including COPD and asthma)
3 main events in airway obstruction:
1) Mucosal invagination due to inflammation and oedema, which narrows the lumen 2) Increased tonicity in away smooth muscle 3) Alveolar wall breakdown
What is the main cell causing inflammation in COPD?
Neutrophil
What is the main cell causing inflammation in asthma?
Eosinophil
What is COPD?
Progressive disease state characterised by airflow limitation that is not fully reversible, characterised by chronic bronchitis and emphysema
What conditions does COPD encompass?
Chronic bronchitis and emphysema (and airway narrowing)
What is chronic bronchitis?
Mucous hyper secretion due to mucous gland hypertrophy and increased number of goblet cells resulting from inflammation of bronchi and bronchioles
What is emphysema?
Distention and damage of the alveoli with destruction of their walls leading to reduced gas exchange - becomes one large pouch’
What is asthma?
Disease characterised by airway inflammation with increased airway responsiveness resulting in airway obstruction
What is the asthma triad (characteristics of asthma)?
1) Airway inflammation (due to eosinophils) 2) Reversible airflow obstruction 3) Airway hyper responsiveness (smooth muscle becomes twitchy)
Difference between asthma and COPD in general?
Asthma is caused primarily by airway inflammation and hyperreactivity leading bronchial muscle contraction that is reversible, while COPD is structural and histological changes (i.e. narrowing and remodelling) that is only partially reversible.
What is atopic vs non-atopic asthma?
Atopic (60%) asthma indicates there is an allergic (IgG) reaction involved, non-atopic does not
What is extrinsic vs intrinsic asthma?
Extrinsic means there is an identifiable external trigger involved, while if there is no identifiable factors then it is intrinsic
What is the dynamic evolution of asthma over time?
1) Bronchoconstriction (causing brief symptoms) 2) Chronic airway inflammation 3) Airway remodelling (scarring due to persistent inflammation leading to fixed airway obstruction)
What are the aims of treatment of asthma, considering the dynamic evolution?
Clear brief symptoms, Reverse exacerbations AHR and prevent fixed airway obstruction
What are the hallmarks of remodelling in asthma?
- Basement thickening - Collagen deposition in the submucosa - Hypertrophy of the smooth muscle
What is the inflammatory cascade in asthma?
1) Genetic loading for the cascade (initiates cascade when interact with triggers) 2) Eosinophilic inflammation occurs 3) Release of preformed allergic mediators e.g. histamine, leukotriene D4 and TH2 cytokines 4) Twitchy smooth muscle occurs (hyper-reactivity)
What is the treatment for Stage 1) Genetic loading in the inflammatory cascade in asthma?
Avoidance of the trigger
What is the treatment for Stage 2) Eosinophilic inflammation in the inflammatory cascade in asthma?
Anti-inflammatories e.g. corticosteroids
What is the treatment for Stage 3) Release of allergic mediators in the inflammatory cascade in asthma?
Anti-leukotrienes/histamines and anti-IgE
What is the treatment for Stage 4) Twitchy smooth muscle in the inflammatory cascade in asthma?
Bronchodilators to relax the bronchial smooth muscles, or muscarine antagonists to block airway constriction
Why are inhaled corticosteroids the mainstay of first line treatment for asthma?
They are the only class of drugs which will converted the anatomical mess of airway inflammation into organised anatomy
What are the diagnostic indicators of asthma?
-Reduced forced expiratory ratio (Fev1/FVC
What is the inflammatory cascade in the development of COPD?
1) Cigarette smoke or other noxious particles 2) activate resident alveolar macrophages and airway epithelial cells 3) These release cytokines 4) Activation of neutrophils, CD8 T cells, increased macrophage numbers 5) Neutrophils and macrophages release proteases that break down connective tissue in the lung parenchyma and also stimulate hyper secretion 6) Result in chronic bronchitis and emphysema
Diagnostic factors of COPD:
- Chronic symptoms (not episodic like asthma) - Smoking - Non-atopic - Daily productive cough - Progressive SOB - Frequent infective exacerbations - Expiratory wheeze from chronic bronchitis - Reduced breath sounds from emphysema
What is the progression of disease in COPD?
1) Progressive fixed airflow obstruction 2) Impaired alveolar gas exchange 3) Respiratory failure (decreased PaO2 and Increases PaCO2) 4) Pulmonary hypertension 5) Right ventricular hypertrophy/failure 6) Death
What are the main differences between asthma and COPD?
.
Asthma vs. COPD: Smoking
Asthma = non-smokers COPD = smokers
Asthma vs. COPD: Allergic
Asthma = allergic COPD = non-allergic
Asthma vs. COPD: Onset
Asthma = early or late COPD = late
Asthma vs. COPD: Symptoms duration
Asthma = intermittent COPD = chronic
Asthma vs. COPD: Inflammatory cells involved
Asthma = Eosinophils COPD = Neutrophils
Asthma vs. COPD: Diurnal variation
Asthma = Diurnal variaion COPD = None
Asthma vs. COPD: Corticosteroid and bronchodilator response
Asthma = Good COPD = Poor
Asthma vs. COPD: Progression
Asthma = none COPD =progressive decline
Asthma vs. COPD: FVC and TLCO
Asthma = Preserved COPD = Reduced
Asthma vs. COPD: Gas exchange
Asthma = Normal COPD = Impaired
Asthma vs. COPD: Cough
Asthma = non-productive cough COPD = productive cough
What classes as ‘brittle asthma’?
Wide PEF variability or sudden attacks when otherwise well controlled
What classes ‘moderate asthma exacerbation’?
PEF >50-75% predicted with increasing symptoms but no signs of acute asthma
What classes ‘acute severe asthma?’
Any one of: - PEF 33-50% predicted - RR>25/min - HR >110/min - Inability to complete sentences in one breath
What classes ‘life threatening asthma’?
Any one of the following seen in acute severe patients: - Altered conscious level - Exhaustion - Arrhythmia - Hypotension - Cyanosis - Silent chest - Poor respiratory effort - PEF
What classes ‘near fatal asthma’?
Raised PaCO2 and/or requiring mechanical ventilation with raised inflation pressures
How is smoking involved in the pathogenesis of COPD?
Smoking-tobacco smoke increases the number of neutrophils and macrophages in the lungs, its slow transit of these cells promotes neutrophil degranulation and inhibits a1-antitrypsin
Which 2 coniditons make up COPD?
Chronic bronchitis and emphysema
Chronic bronchitis
Cough productive of sputum on most days for 3 months of at least 2 consecutive years.
Chronic irritation leads to increased mucus production associated with goblet cell metaplasia, macrophage accumulation and fibrosis around bronchioles generate functional obstruction
Emphysema
Increase beyond normal size in distal airspaces to terminal bronchiole due to loss of alveolar walls (tissue destruction) due to protease activity.
Emphysema impairs respiratory function –diminished alveolar surface area for gas exchange. Loss of elastic recoil and loss of support of small airways leads to tendency to collapse.
Asthma
Chronic inflammatory disorder (eosinophilic infiltration) characterised by hyper-reactive airways leading to episodic reversible bronchoconstriction
