103 - COPD Flashcards
What makes up COPD?
Chronic bronchitis
Emphysema
(assoc with small airways disease)
What is bronchitis?
Cough, purulent sputum for 3+ months of the year for 2 years
What changes occur in bronchitis?
Inflammation and narrowing - epithelium infiltrated by neutrophils - fibrosis
Increased mucous secretion
Squamous metaplasia - loss of cilia
What is emphysema?
Destruction of lunch tissue distal to terminal bronchioles - loss off elasticity + radial traction
What changes occur in emphysema?
Inflammation, proteases released, collagen and elastic breaks down - floppy airways, collapse on expiration
Hyperinflation
What deficiency might cause an increased risk of emphysema?
Alpha-1 antitrypsin deficiency
There are 2 types of respiratory failure in COPD, what are they?
Type 1 - pink puffers - emphysema - low PaO2, normal/low PaCo2, respiratory drive is maintained
Type 2 - Blue bloaters - Bronchitis - Low PaO2, High PaCo2 - Can’t keep high enough resp effort to keep PaCo2 down
What types of bronchodilators are there?
B2 agonists - Salbutamol (SABA), Salmetrol (LABA)
Muscarinic antagonists - anticholinergics = Ipatropium, Tiotropium
What is a side effect of an anticholingeric drug (eg. ipatropium)
Dry mouth
What are the phyiological 4 aspects of respiration?
Ventilation
Diffusion
Perfusion
Ventilation-perfusion relationships
How do you measure ventillation?
Spirometry
Total ventilation = tidal vol X resp frequency
What drives air in and out of the lungs?
convection - pressure gradient
What determines the functional residual capacity?
Balance of elastic recoil of lungs inwards, and the chest outwards
What is fick’s law?
The rate of diffusion is proportional to the area of alveoli, inversly proportional to the thickeness
What does tha Va/Q relationship determine?
Gas exchange
What is the optimum Va/Q?
1
Normal lung is 0.84
What is the Va/Q of the apex of the lung, why?
More than 1
Apex is poorly perfused
Both perfusion and ventilation is reduced due to gravity, bur gravity affects blood most
What is the Va/Q of the base of the lungs? Why?
Less than 1
Base poorly ventilated
Both increased due to gravity, but affects blood most
What condition do you get a lower than expected Va/Q?
Chronic bronchitis, asthma
Poor ventilation, impairs gas exchange, low PaO2 and impaired CO2 excretion
What condition causes a higher than expected Va/Q?
Pul embolism
COPD
Poor perfusion means you get a high PaO2 but a low PaCO2, ventilation is wasted
What does a Va/Q of 0 mean?
There is no ventilation - there must be a shunt
What does a Va/Q of infinity mean?
There is no perfusion
occurs in dead space
Which nerve supplies the respiratory muscles involved in control of ventilation?
Phrenic nerves
What is the most important factor involved in controlling ventilation in normal people?
PaCO2
Where is PaCO2 levels detected?
Central - medulla PaCO2 (80% of drive)
Peripheral - Carotid and aortic bodies PaCO2 and PaO2
Stretch receptors
Where is lymph from the lungs drianed?
Bronchopulmonary nodes - tracheobronchial nodes - Bronchomediastinal nodes
What level are the inferior boarders of the lung and plura?
Lung - 6, 8, 10th rib
Pleura - 8, 10, 12th rib
