Obstructive and Restrictive Pulmonary Disease Flashcards
What happens to overall size of the lungs in obstructive disease compared to a normal lung?
It gets bigger. This is due to air getting trapped prior to breathing in (after breathing out in the previous breath)
What happens to overall size of the lungs in restrictive disease?
The reduced compliance of the lung prevents it from inflating as much as it should thus making it smaller overall.
What is FVC?
The maximum amount of air that can be forced out after taking the deepest breath possible.
What is FEV1?
Amount of air that can be expired forcefully in 1 second.
What happens to FEV1:FVC ratio in obstructive lung disease?
It is decreased due to slower expelling of air from the lungs as a result of the obstruction.
FVC is typically normal in obstructive lung disease or it can be slightly decreased (probably due to trapping of gas)
Examples of Obstructive Lung Diseases:
Chronic bronchitis (mucous gland hypertrophy, hyperplasia, and hypersecretion)
Bronchiectasis (airway dilation and scarring)
Asthma (Smooth muscle hypertrophy and hyperplasia, mucous secretion and inflammation)
Emphysema (Air space enlargement and wall destruction)
Bronchiolitis (inflammatory scarring and partial obliteration of bronchioles)
What is asthma?
A chronic inflammatory disorder characterised by hyper-responsive airways. (people become overly-reactive to stimuli reversibly undergoing bronchospasm/bronchoconstriction
What are the types of asthma and their subtypes?
Extrinsic asthma: Atopic asthma, Drug-induced asthma, and Occupational asthma
Intrinsic asthma: Non-atopic asthma
What is atopic asthma?
Allergic asthma which is caused by type I IgE mediated hypersensitivity reaction. This is often triggered by allergens such as dust, pollen, infections and animal hair.
What is non-atopic asthma?
Asthma that isn’t triggered by allergic reactions. (negative allergen tests and aren’t always associated with family history, typically overlaps with bronchitis and mostly in people who smoke)
What are the symptoms of asthma?
Severe dyspnoea with wheezing which lasts for several hours or more and subsides naturally or responds to bronchodilators.
What is the mortality rate of asthma?
0.2% per annum
What is the condition in which asthma fails to subside for days/weeks called? What can this condition cause?
Status asthmaticus which can cause respiratory failure and death
How is asthma treated?
Prevention of asthma attacks are the mainstay of treatment
Is childhood asthma permanent?
No it may resolve with adulthood in approximately 50% of people
What happens in people with asthma?
Classic atopic asthma is associated with excessive type 2 helper T cells releasing IL-5, IL-13, and IL-4 and IL-3
In asthmatics what does IL-5 trigger?
Eosinophil activation
In asthmatics what does IL-13 trigger?
Mucus production
In asthmatics what do IL-3 and 4 trigger?
Mast cells degranulate
What are the phases of an asthma reaction? What happens during these phases?
Early phase (bronchoconstriction, increased mucous production, and vasodilation)
Late phase (Inflammatory mediators stimulate epithelial cells to produce chemokines and recruiting of Th2 cells and eosinophils which amplifies inflammatory response)
What happens to lung tissue in response to repeated infection?
Airway remodeling as a result of smooth muscle hypertrophy, mucous gland hypertrophy, and increased collagen deposition.
This has often already occured by the time the patient shows up in clinic
What happens histologically to lung tissue in asthma?
Mucus plugging of bronchi
Focal necrosis of epithelium
Eosinophilic inflammation
Oedema of bronchial walls
Thickening of epithelial basement membrane
Hypertrophy of bronchial mucous glands
Hypertrophy of smooth muscle of bronchial wall
The formation of Charcot-Leyden Crystals
Curschmann’s spirals
What are Charcot-Leydin Crystals?
Crystals that form from reaction between eosinophil granules and proteins
What are Curschmann’s spirals?
Casts of airways formed by mucin and cell debris
What is emphysema?
Abnormal permanent enlargement of airspaces distal to terminal bronchiole (just before the alveoli) WITHOUT obvious fibrotic damage
What abnormal lung changes does emphysema result in?
Trapping of air in dilated airspaces and loss of elastic recoil of the lungs (when breathing out) due to damage of parenchyma
What causes emphysema?
2 main causes:
Smoking / air pollution / industrial exposure and accumulation of neutrophils + macrophages in respiratory bronchioles
Genetic predisposition (most common in alpha1-antitrypsin deficiency)
How is damage caused in emphysema?
Acinar (physical) damage + Chronic inflammation + Protease (in neutrophils + macrophages in lung) / anti-protease activity (bronchial mucus)
What does smoking do to lungs that causes emphysema?
It inhibits alpha1 antitrypsin and other antiproteases.
The result is those proteases accumulate causing damage to the lining of the bronchioles in addition to the action of inflammation without being inhibited by the antiproteases.
Where does antitrypsin get produced?
Typically in the liver so cirrhosis of the liver in infancy means there can be severe emphysema in early adult life
How common is homozygous alpha1-antitripsin deficiency? What does this do to levels of antitrypsin and what is the resulting effect?
1 in 7000 adults
10% of normal level of antitrypsin which causes cirrhosis of the liver in infancy and severe emphysema in early adult life
How common is heterozygous alpha1-antitripsin deficiency? What does this do to levels of antitrypsin and what is the resulting effect?
3 - 9% of adults
60% of normal levels, may be asymptomatic but develop emphysema much earlier if exposed to pollutants
What are the clinical symptoms of emphysema?
Progressive dyspnoea when more than a third of lung tissue is affected
Barrel chest expiratory difficulty
Wheezing
Cough if associated with chronic bronchitis
Chest hyper resonant to percussion
Lungs show low desnsity on X-ray
What are the severe complications that result from emphysema?
Respiratory failure with acidosis and coma
Right sided heart failure (due to cor pulmonale)
Pneumothorax (result of direct communication between air inside the lung caused by the damage)
What are the major types of emphysema?
Centriacinar
Panacinar
What are the minor types of emphysema?
Distal acinar
Irregular
What is the difference between centriacinar and panacinar emphysema?
Primarily affects the upper lobes and usually seen in smokers and is 20x more common than panacinar
Panacinar involves all lung fields. Loss of all portions of the acinus from the respiratory bronchiole to the alveoli and normally seen in alpha-1 antitrypsin deficiency
What is the difference between distal acinar and irregular emphysema?
Distal acinar is very uncommon and affects distal portion of acinus whereas irregular emphysema affects acinus irregularly.
Distal acinar often forms bullae (bubbles) whereas irregular emphysema is associated with clinically significant scarring.
What happens to lungs macroscopically in emphysema?
Pale, spongy and almost balloon-like lungs with bullae that can rupture and result in pneumothorax.
Anthracosis is often seen (carbon pigment from smoking, air pollution)
Secondary infections and other lung diseases can often be seen as well.
What happens to lungs microscopically in emphysema?
Damage to alveolar walls and large alveolar spaces
What is chronic bronchitis?
It is a clinical diagnosis which describes the condition in which there is productive cough on most days for 3 months of the year for at least 2 consecutive years.
Approximately 75 mls of sputum per day.
What are the symptoms and signs of chronic bronchitis?
Dyspnoea
Eventually respiratory failure with hypoxaemia, hypercapnia, and cyanosis
What causes chronic bronchitis?
Chronic irritation which leads to hypersecretion of mucus in larger airways with subsequent development of inflammation of bronchi and bronchioles
What are some complications that can arise from chronic bronchitis?
Acute infective episodes with pneumonia or exacerbation of respiratory failure
Cor pulmonale and right heart failure
Squamous metaplasia [from columnar epithelium] ( can lead to dysplasia and malignant change in bronchial epithelium)
Secondary fibrosis of bronchial lumen
What happens to lung tissue in chronic bronchitis?
Increased mucous without eosinophils
Plugging of bronchi in acute exacerbations
Squamous metaplasia
What are pink puffers and blue bloaters?
Pink puffers are mostly people with emphysema who stain pink on histology slides due to air trapping.
Blue bloaters are bronchitis patients who stain blue
What is the difference in symptoms between chronic bronchitis and emphysema?
Bronchitis results in mild + late dyspnoea early and copious production of sputum and increased airway resistance. Chest X-ray shows prominant vessels and a large heart.
Emphysema shows severe and early dyspnoea, late and little sputum/cough, normal airway resistance and low elastic recoil. Chest X-ray shows hyperinflation and small heart.
Does bronchitis show cor pulmonale often?
Yes cor pulmonale is common in chronic bronchitis
Does emphysema show cor pulmonale often?
Rare and when it does show up it is terminal
Are secondary infections commonly seen in bronchitis and emphysema?
In bronchitis they are common, in emphysema they are occassional
How does respiratory insufficiency show up in bronchitis and emphysema?
In bronchitis it is repeated.
In emphysema it is progressive and terminal
What happens to elastic recoil in chronic bronchitis and emphysema?
Emphysema results in low recoil and bronchitis results in normal recoil
What is bronchiectasis?
Permanent and abnormal dilation of the bronchi and bronchioles as a result of bronchial obstruction, infection, or both.
What are the symptoms of bronchiectasis?
Persistent cough with foul-smelling sputum
Sometimes haemoptysis (couhging up blood)
Cough tends to be paroxysmal on awakening
Can surgery fix bronchiectasis?
Only if the bronchiectasis is localised.
What causes bronchiectasis?
Tumour or foreign body obstruction
Infection
Congenital disorders such as cystic fibrosis
What are some congenital disorders that can result in bronchiectasis?
Cystic fibrosis
Mucoviscidosis
Kartagener’s syndrome
Defect in development of bronchi
What happens to obstructed lungs?
Obstruction leads to distal collapse, inflammation and accumulation of secretions expanding the bronchial tissue and causing necrosis in surround lung tissue and fibrous replacement by scar tissue that contracts exerting traction on airways which dilate.
What kind of diseases cause restrictive lung diseases?
Chest wall disorders
Chronic interstitial diseases
Acute lung injury/adult respiratory distress syndrome
What is acute lung injury?
Abrupt onset of significant hypoxemia and diffuse pulmonary infliltrates in the absence of cardiac failure (acute respiratory distress and respiratory distress of the newborn)
What happens in acute lung injury?
Inflammation-associated increase in vascular permeability and epithelial + endothelial cell death.
What is the mortality of acute lung injury?
~40%
What do histological slides of acute lung injury show?
Diffuse alveolar damage with hyaline membranes (pink membranes), haemorrhagic and heavy lungs, reactive proliferation of type II pneumocytes.
Most acute lung injury has a known aetiology most common is sepsis
What are chronic interestitial lung diseases?
A heterogeneous group of disorders characterised by inflammation and fibrosis of pulmonary connective tissue, principally the interstitium between alveolar walls.
What causes chronic interstitial diseases?
A lot of overlap between the diseases’ histologic features but the reason is unknown.
What is the pathological reason of most chronic interstitial lung diseases?
Inflammation and fibrosis of pulmonary connective tissue principally the interstitium between alveolar walls.
What is the most common cause of chronic interstitial lung diseases?
Pulmonary fibrosis
What percentage of non-infectious diseases seen by pulmonary physicians are caused by chronic interstitial lung diseases?
15%
What features are common to all chronic interstitial lung diseases?
Reduced compliance
Reduced diffusion capacity
Reduced lung volume
What should be considered when trying to understand the kind of chronic interstitial lung disease we are dealing with?
Distribution (anatomical/spatial)
Distribution (temporal)
Known aetiology vs idiopathic
What are the categories of chronic interstitial lung diseases?
Fibrosing diseases
Granulomatous diseases
Eosinophilic
Smoking related
Other
What are some fibrosing diseases?
Usual interstitial pneumonia (idiopathic pulmonary fibrosis)
Non-specific interstitial pneumonia
Cryptogenic organising pneumonia
Autoimmune related
What are some granulomatous causes of chronic interstitial lung diseases?
Sarcoid
Hypersensitivity pneumonitis/extrinsic allergic alveolitis
What are the chronic interstitial lung diseases commonly caused by smoking?
Desquamative interstitial pneumonia
Respiratory bronchiolitis
What is Usual Interstitial pneumonitis / Idiopathic Pulmonary Fibrosis?
An interstitial pneumonitis of unknown cause
What happens in UIP/IPF to the lungs?
Temporally heterogeneous damage which means damage in some areas is acute and others is a result of chronic damage.
Subpleural damage
Fibroplastic foci which are patchy type fibrosis of interstitium.
Eventually the diease develops a pattern called honeycomb lung.
What is the median survival rate of UIP/IPF?
<5 years
What does UIP/IPF look like radiologically?
Classical radiological appearances which are similar to that of chronic hypersensitivity pneumonia and asbestos toxicity
Why does airway narrow in asthma?
Increase mucus secretion
Increase airway smooth muscle constriction (spasm)
Increase thickening airway wall (from inflammation)
