Chronic Obstructive Pulmonary Disease
Prevalence: 600,000 Canadians [1.7% of pop.]
Mortality: 5 cause in men [4.5 per 100,000]
4 in women [2.8 per 100,000]
Smoking in 80-90% of individuals with COPD
50% of smokers have sub-clinical COPD
Smoking “increases” your risk for lung cancer but doesn’t cause it
Smoking causes COPD
Whenever we get a cold we get an obstruction of the airways but this is acute, in COPD cases
it is chronic, which can eventually lead to heart disease
Person with COPD has an airway problem (can be reversible) and a pulmonary problem
(irreversible most of the time)
Steps of COPD
Step 1: Smoking
Step 2: Chronic bronchitis
Step 3: Emphysema
Step 4: Chronic hypoxemia
Step 5: Cor pulmonale
this all takes YEARS to develop but we only start seeing it happen in the 50’s because of
irreversible pulmonary disease
Step 2 – Chronic Bronchitis
The first thing is that it injures epithelial cells in the bronchi. When cells get attacked they are
injured and the epithelial cells have glands (secret mucous) that react to fight and protect. That’s
why you see that the first thing that happens when you start smoking is that you start losing
more secretions because this is a defense mechanism in the airway.
Chronic smoking causes many of the cells to die.
The danger is in the ones that adapt. The respiratory epithelium is ciliated. When these cells
are attacked they become metaplasia. The respiratory epithelium becomes squamous
epithelium. This epithelium does have any cilia, therefore when you get a cold it’ll take a lot
longer to get over the cold. This can also cause infection.
Smoke has carcinogens so many of the cells that adapt will be defected.
Chronic bronchitis is airways that are full of mucous all the time.
If you stop smoking the dysplasia will disappear and most of the cilia will come back.
Air trapping is a big problem for people with chronic bronchitis
The second thing that happens is something that is called bronchiectasis. This is dilation of
the bronchi. This is because chronically inflamed walls can become permanently dilated. This
will cause turbulence and mucous, fungi and bacteria, biofilms will form there (people will have
infections all the time).
Once you have weakened bronchial walls, it’ll never go away (if you stop smoking). Step 3 – Emphysema
is pulmonary damage caused by obstruction called emphysema.
It is basically a lung with a lot of holes. If these holes break (pleura) the lungs might collapse
this is called pneumothorax.
Air trapping will increase the pressure inside all of the alveolar sacs.
Whenever you smoke you are inducing inflammation in the alveolar walls and eventually this
wall will be destroyed and that’s how these holes happen.
The alveolar walls are essential for gas exchange and they have the capillaries that come from
the pulmonary arteries.
If you started smoking, it would damage your alveolar walls.
The roll of macrophages is to phagocytosis anything that comes through the air.
So if you smoke the macrophages will try to eat the
Whenever you smoke the deeper you inhale the more stuff will get into your
alveolar walls and this will cause acute inflammation.
Elastase is an enzyme that is released to clean up the inflammatory cells. These
are very bad in the lungs because they will be destroyed and this will cause the
alveolar walls to become weaker.
Some families have more anti-elastase and protection, and some of them have
inherited alpha1 antitrypsin which neutralized elastase which protects them
against COPD and emphysema. Step 4- Chronic Hypoxemia
This shows why hypoxemia occurs
In smokers you get impaired ventilation, collapsed alveoli or alveolar dead space (although
air goes in there is no blood going in)
When the venous blood bypasses the lungs is it called shunting (short cut that the blood takes
so it doesn’t get oxygenated) the more emphysema the more shunting.
Whenever this person gets an infection that they will go into respiratory acidosis and they will
be chronically hypoxemic.
Because the alveolar walls are required to remove CO2 then CO2 will not be removed causing
hypercapnia (person will breath more, look like they’re in distr