Pathology of obstructive lung disease Flashcards
What are the three main obstructive airway diseases ?
Asthma
Chronic bronchitis (COPD)
Emphysema (COPD)
What are the normal values for FEV1, FVC and the ratio between them ?
Normal FEV1 - 3.5-4L
Normal FVC - 5L
Ratio FEV1:FVC - 0.7-0.8
What is used to predict FVC ?
Age
Sex
Height
Besides FEV1/FVC ratio, how else can an obstructive lung disease be demonstrated ?
Peak expiratory flow rate (PEFR)
What are the normal values for PEFR ?
Normal 400 – 600 litres/min
Normal range is 80-100% of best value
What is PEFR moderate fall ?
50-80% of best
What is PEFR marked fall ?
<50-80% of best
What is FEV1, FVC, and PEFR in obstructive lung diseases ?
Airflow limitation PEFR is reduced FEV1 is reduced FVC may be reduced FEV1 is less than 70% of FVC
What type of hypersensitivity is bronchial asthma ?
Type 1 hypersensitivity in the airways
What causes the decrease in diameter size in bronchial asthma ?
Degranulation of mast cells and smooth muscle contraction
What physical substances obstruct airways in chronic asthma ?
Oedema
Mucus
Plasma exudation
What can ease bronchial constriction ?
Use of drugs, or spontaneously
What is COPD ?
Chronic and irreversible small airway obstruction
What is chronic bronchitis ?
Chronic and irreversible small airway obstruction with mucus production and inflammation
What is emphysema ?
Chronic and irreversible small airway obstruction with permenant enlargement of air spaces distal to terminal bronchiole and alveolar wall destruction
What is the aetiologies of COPD ?
SMOKING
Atmospheric pollution
Occupational- dust
What is a rare cause of emphysema ?
Alpha-1-antiprotease deficiency
What is the mechanisms of obstruction in large airways in COPD ?
Little contribution by glands and mucous
What is the mechanisms of obstruction in small airways in COPD ?
Smooth muscle tone
Inflammation
Fibrosis
Partial collapse of airway wall on expiration
In emphysema- loss of alveolar attachments
What portion of COPD is reversible ?
Smooth muscle tone
Inflammation
Respond to pharmacological intervention
What is chronic bronchitis defined as clinically ?
Cough production of sputum most days in at least 3 consecutive months for 2 or more consecutive years
What is complicated chronic bronchitis ?
When sputum turns mucopurulent (acute infective exacerbation)
FEV1 falls
What does chronic bronchitis exclude ?
TB
Bronchiectasis
These may be confused with asthma
What are the morphological changes in the large airways in COPD ?
Mucous glands hyperplasia
Goblet cell hyperplasia
Inflammation and fibrosis- minor component
What are the morphological changes in the small airways in COPD ?
Goblet cells appear
Inflammation and fibrosis in long standing disease
What is the pathological definition of emphysema ?
Increase beyond the normal in the size of airspaces distal to the terminal bronchiole arising from wither dilation or from destruction of their walls without obvious fibrosis
Loss in alveolar tissue, more space between alveoli.
What is an acinus ?
A region of the lung supplied with air from one of the terminal bronchioles
What is centiacinar emphysema ?
Loss of lung tissue is concentrated at middle of acinus
Then alveolar tissue is lost
Predominates in the upper part of the lungs
What is panacinar emphysema ?
Emphysema affecting all parts of the secondary pulmonary lobule, typically involving the inferior part of the lung and often associated with a α1-antitrypsin deficiency
What is periacinar emphysema ?
Tissue loss around edges of acinus
What is a bulla ?
Emphysematous space greater than 1cm
What is a bleb ?
A bulla just underneath the pleura
What is the pathogenesis of emphysema ?
Smoking (protease-antiprotease imbalance)
Ageing
Alpha-1-antitrypsin deficiency
Why is there hypoxaemia in COPD ?
Airway obstruction
Reduced respiratory drive
Loss of alveolar surface area
Shunt- only during severe acute infective exacerbation
What causes physiological pulmonary vasoconstriction ?
When alveolar oxygen tension falls
How is Physiological pulmonary arteriolar vasoconstriction protective ?
Do not send blood to alveoli short of oxygen
What is Cor pulmonale ?
Hypertrophy of the RV resulting from disease affecting the function or structure of the lung
Except where pulmonary alterations are the result of diseases primarily affecting the left side of the heart or congenital heart disease
What causes pulmonary hypertension ?
Pulmonary vasoconstriction
Pulmonary arterioles- muscle hypertrophy and intimal fibrosis
Loss of capillary bed
Secondary polycythaemia
Bronchopulmonary arterial anastomoses
