Lecture 23: COPD Flashcards
define COPD
A lung disease caused by inflammation of the small airways. Includes chronic bronchitis (characterized by productive cough ≥ 3 months in 2 consecutive years) and emphysema (dilation of the air spaces distal to the terminal bronchioles). Most cases of COPD (~ 90%) are caused by smoking.
• Group of diseases with respiratory symptoms of dyspnoea, cough, sputum production
• Airflow limitation and chronic inflammation of lung
does airflow limitation of COPD is reversible?
Its pulmonary component is characterized by airflow limitation that is not fully reversible.
what is the cause of airflow limitation in COPD?
The airflow limitation is usually progressive and associated with an abnormal inflammatory response of the lung to noxious particles or gases.
FEV1/FEV is >80 % in COPD.T/F
False
COPD is a lung disease characterized by airflow limitation (FEV1/FVC ratio of less than 70%) that is not fully reversible (FEV1 increase of 200 ml and 12% improvement above baseline FEV1 following administration of either inhaled corticosteroids or bronchodilators).
FEV1 increase of 200 ml and 12% improvement above baseline FEV1 following administration of either inhaled corticosteroids or bronchodilators are suggesting of COPD. T/F
False
It is suggestive of Asthma (reversible obstruction)
COPD comprises of 2 predominant conditions:…
Chronic bronchitis and Emphysema
define chronic bronchitis
Chronic Bronchitis is defined as a productive cough for 3 months in each of 2 successive years in a patient whom other causes of chronic sputum has been excluded.
define the emphysema
Emphysema is defined as the presence of enlargement of airspaces distal to the terminal bronchioles or acinus with destruction of their walIs without obvious fibrosis.
what is the epidemiology of COPD?
• COPD affects >10% of the population of the USA; 200 million people worldwide
• Objective evidence of persisting and irreversible airflow obstruction
• Affects 14% of male smokers versus 3% of non- smokers (i.e smoking is not the only cause of COPD!)
• COPD is the fourth leading cause of death in western world
• The only common cause of death increasing in incidence
–Sex: 3:2 male/female ratio
–The third most common cause of death worldwide
–Prevalence: 6%
at what FEV value symptoms start to occur?
- Accelerated decline in forced expiratory volume in 1 second from the normal rate in adults over 30 years of approximately 30 – 60 ml per year.
- Initially asymptomatic but lung function is deteriorating
- Symptoms occur once FEV is < 50% predicted
what are the causes of COPD?
• 90% of cases occur in chronic smokers
• 25% of heavy smokers have chronic bronchitis
• Age: high risk
• Environment: urban > rural
– Air pollutants including sulfur dioxide, nitrogen dioxide
• Dusty occupations (coal, quartz, silica, welding)
• Passive smoking
• Low birth weight; chest infections in the first year of life (eg adenovirus)
besides smoking, air pollutants also cause COPD. T/F
True
- -Air pollutants including sulfur dioxide, nitrogen dioxide
- -Dusty occupations (coal, quartz, silica, welding)
- -onorganic dust: such as industrial bronchitis in coal miners
- -Organic dust: ↑ incidence of COPD in areas where biomass fuel (e.g., wood, animal dung) is regularly burned indoors
does passive smoking increase the risk of COPD?
Yes
If precautions against smoke exposure not taken, those who live in close proximity to smokers (e.g., children, relatives) have a significantly higher risk of COPD. The risk of asthma progressing to COPD also increases with exposure to smoke.
Low birth weight; chest infections in the first year of life (eg adenovirus) can result in COPD.T/F
True
The lower the birth weight, the higher the risk of developing COPD.
what is the main causative factor of COPD?
Smoking is the main cause of COPD, but only one in five smokers is affected, so it is likely that a genetic predisposition also plays a role in development of the disease.
what are the endogenous factors increasing the risk of COPD?
- -α1-Antitrypsin deficiency
- -Antibody deficiency syndrome (e.g., IgA deficiency)
- -Primary ciliary dyskinesia (e.g., Kartagener syndrome)
The defining feature of chronic bronchitis is that mucus hypersecretion is primarily a reflection of alveolar involvement. T/F
False
bronchial involvement
what is the cause of airflow limitation in chronic bronchitis?
• Airflow obstruction component is due to peripheral involvement with:
– Inflammation, fibrosis and resultant narrowing of bronchioles (small airway disease)
– Co-existent emphysema
what is the pathogenesis of chronic bronchitis?
• Hypersecretion of mucus, beginning in the large airways
• Irritants induce hypersecretion of the bronchial mucus glands -> hypertrophy of mucus glands -> metaplastic formation of mucin secreting goblet cells in the surface epithelium
• Irritants also induce inflammation with CD8+ T lymphocytes, macrophages and neutrophils
• Gross appearance: Airways swollen and erythematous, covered by a layer of mucin / mucopurulent secretions
• Histologically:
–Hypertrophy of mucus-secreting glands
–Increase in number of goblet cells in the lining epithelium
–Loss of ciliated epithelial cells
–Inflammatory cell infiltrate
–May eventually lead to squamous metaplasia -> dysplasia -> squamous cell carcinoma
CD4 T lymphocytes mediate inflammation in chronic bronchitis. T/F
False
Increased number of neutrophils, macrophages, and CD8+ T lymphocytes → release of cytokines → amplification of inflammation and structural changes of lung parenchyma (e.g., growth factor release)
CD8 vs CD4 T cells in obstructive lung diseases?
CD8+ T lymphocytes mediate inflammation in individuals with COPD. CD4+ T lymphocytes and eosinophils mediate inflammation in individuals with bronchial asthma.
what is the cause of goblet cell proliferation seen in COPD?
Irritants induce hypersecretion of the bronchial mucus glands -> hypertrophy of mucus glands -> metaplastic formation of mucin secreting goblet cells in the surface epithelium
what is the Reid index?
The ratio of the width of the mucus-secreting glands to the combined width of the epithelium and cartilage in the bronchial tree. > 0.5 is characteristic of chronic bronchitis.
what is the consequence of chronic irritant exposure in COPD?
- -Overproduction of growth factor → peribronchiolar fibrosis → narrowing of airway → obliteration → emphysema (airflow limitation)
- -Smooth muscle hyperplasia of the small airways and pulmonary vasculature (mainly due to hypoxic vasoconstriction) → pulmonary hypertension → cor pulmonale
how bronchopulmonary tissue is destructed in COPD?
- -Bronchopulmonary inflammation ↑ proteases, and nicotine use (or other noxious stimuli) inactivates protease inhibitors (especially α1-antitrypsin) → imbalance of protease and antiprotease → ↑ elastase activity → loss of elastic tissue and lung parenchyma (via destruction of the alveolar walls), which causes:
- -Enlargement of airspaces → ↓ elastic recoil and ↑ compliance of the lung → ↓ tethering of small airways → expiratory airway collapse and obstruction → air trapping and hyperinflation → ↓ ventilation (due to air-trapping) and ↑ dead space → ↓ DLCO and ↑ ventilation-perfusion mismatch (Va/Q) → hypoxemia and hypercapnia
- -↓ Blood volume in pulmonary capillaries → ↑ dead space → ↓ DLCO and ↑ Va/Q → hypoxemia and hypercapnia
what are the hallmarks of chronic bronchitis?
- -Mucus gland hypertrophy
- -Increase in goblet cells
- -Loss of ciliated cells
- -May get squamous metaplasia
what is the clinical course of chronic bronchitis?
- Cough with production of sputum may persist without ventilatory dysfunction
- May progress to significant COPD with airflow obstruction -> hypercapnia, hypoxaemia and cyanosis
- Severe forms may develop pulmonary hypertension and cardiac failure
- Recurrent infections and respiratory failure
what is the morphologic definition of emphysema?
Permanent enlargement of air spaces distal to the terminal bronchioles accompanied by destruction of their walls
what is the epidemiology of emphysema?
- Males >females
- Heavy smokers
- Develops over many years becoming clinically significant in later life
the air conducting part is lost in emphysema. T/F
False
Anatomically, emphysema involves the acinus, a structure distal to the terminal bronchiole
• This air exchanging portion of lung is lost in emphysema
what is the respiratory acinus?
A part of the airway distal to a terminal bronchiole. Each acinus contains multiple respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli.
what is the pulmonary lobule?
- Hexagonal area of lung parenchyma 1 - 2 cm across outlined by fibrous septa
- Contains lung tissue supplied by 3 - 5 terminal bronchioles
- Consists of 3 - 5 respiratory acini
- Grossly visible