obstructive airway diseases Flashcards
what are examples of COPD
chronic bronchitis and emphysema
what is FEV1
forced expiratory volume of air exiting the lung in the first second of exercise
what is FVC
the final total amount of air expired
what is the usual value of FEV1
ABOUT 70-80% OF FVC
NORMALY ABOUT 3.5-4L
FVC IS ABOUT 5
NORMAL RATIO OF FEV1:FVC IS0.7:0.8
what’s another way that obstructive lung disease may be demonstrated
PEFR - peak expiratory flow rate
normally - 400 -600 litres
normal range is 80-100% of best value
50-80% is moderate fall and below 50 is marked fall
what are key features of obstructive king disease
airflow limitation PEFR is reduced FEV1 reduced FVC may be reduced FEV1 is less than 70% of FVC
what is bronchial asthma
type 1 hypersensitivity in the airways
describe bronchial asthma
generally considered to be reversible airways obstruction either spontaneously or as a result of medical intervention
bronchial smooth muscle contraction and inflammation can be modified by drugs
describe the aetiology of chronic bronchitis and emphysema
smoking
atmospheric pollution
occupation:dust
alpha anti protease (anti trypsin) deficiency is an extremely rate cause of emphysema
effect of age and susceptibility
prévalence - men>women but increasing in developing countries
how is chronic bronchitis defined clinically
cough productive of sputum most days in at least 3 consecutive months for 2 or more consecutive years
complicated when sputum turns mucopurulent (acute infective exacerbation) or FEV1 falls
what are morphological changes in chronic bronchitis
large airways - mucous gland hyperplasia, goblet cell hyperplasia and inflammation and fibrosis is a minor component
small airways - goblet cells appear, inflammation and fibrosis in long standing disease
what is the pathological definition of emphysema
increase beyond the normal size of airspace’s distal to the terminal bronchiole arising either from dilation or from destruction of their walls and without obvious fibrosis
what are the diff forms of emphysema
centriacinar
panacinar
periacinar
scar ‘irregular’ ‘bullous emphysema’
what is centriacinar
most common type of pulmonary emphysema mainly localised to the proximal resp bronchioles and predominantly found in upper lung zones
what is panacinar
dilation of air space from resp bronchioles to alveoli
what is a bullous emphysema
known as vanishing king syndrome. most often treated by surgical removal of bulls which can grow to 20 cm
why can COPD lead to hypoxaemia
airway obstruction
reduced resp drive
loss of alveolar surface area
shunt - only during severe acute infective exacerbation
what are the pulmonary vascular changes in hypoxia
physiological pulmonary arteriolar vasoconstriction
- when alveolar oxygen tension falls
- can be localised effect
- all vessels construct is there is hypoxaemia
protective mechanism
- do not send blood to alveoli short of oxygen
what is chronic (hypoxic) cor pulmonale
hypertrophy of the right ventricle resulting from disease affecting function and/or structure of lung, except where pulmonary alterations are the result of diseases primarily affecting left side of the heart or congenital heart disease
hypoxic for pulmonale
why can it lead to pulmonary hypertension
pulmonary vasoconstriction pulmonary artérioles - muscle hypertrophy and intimal fibrosis loss of capillary bed secondary polycythaemia bronchopulmonary arterial anastomoses
