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What is COPD?

What is COPD?
What is COPD?
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Chronic Obstructive Pulmonary Disease (COPD) is a lung disease that is chronic and incurable. It characteristically involves both large and small airways and the lung parenchyma, that is, the lung tissue itself. Airways are living pipes that connect your mouth to alveoli (oxygen exchange units that are deep inside your lungs) and as you get deeper into the lungs airways get smaller and smaller. Think of airways as pipes that simply transport air, which of course includes oxygen.


Key stats about COPD:

  • It affects more than 5% of the population meaning if you don’t suffer from COPD you at least know someone who does.
  • It is the third most common cause of death in the US. Killing 120,00 Americans each and every year.
  • Because so many Americans suffer from COPD coupled with the fact that it’s chronic and incurable but manageable means frequent doctor visits and hospitalization.


COPD Pathophysiology:

By pathophysiology I mean how lungs go from normal to lungs that are sick with COPD.

  • Chronic bronchitis: By definition, chronic bronchitis is a daily productive cough for three consecutive months provided other causes of chronic cough have been ruled out.
  • Emphysema is destruction of lung tissue just beyond where the airways end.


Chronic Bronchitis & Airway Damage:

In COPD airways are chronically and irreversibly inflamed. By inflamed think swollen like when you sprain your ankle. Unfortunately unlike your ankle sprain the swelling in COPD is irreversible and permanently ongoing. The “swelling” limits the amount of air that flows causing the following symptoms:

  • The first symptom seen with large airways damage is slight shortness of breath, which may not even be noticed because people limit themselves to avoid it and often think it’s just because they’re getting older. As the damage worsens cough becomes an everyday friend and produces tons of goop. The mucus is usually clear but during COPD flare-ups it turns yellow or green.
  • When small airways get damaged a patient’s chest literally “swells up” because of air trapping.  Physically the patient looks barrel-chested and wheezes.



As COPD progresses the lungs lose their natural elastic recoil and the alveoli are also damaged. This destruction of lung tissue where the airways end is called emphysema.

Every patient with COPD will have both airway damage and alveoli damage. How much they have of one more than the other will dictate how they feel and their symptoms.


What causes COPD?

  • In the US 80% is from cigarette smoking. In the developing world other exposures like biomass fuel use are a big factor.
  • How much you smoke determines whether and how quickly you develop COPD. Generally you need 10-15 pack years before you develop COPD. A pack year is packs of cigarettes per day multiplied by years. In other words smoke two packs a day for twenty years gives you a forty-pack year history.  Smoke enough and inevitably you’ll develop some lung function problems but not everyone gets COPD. On the other hand nearly everybody with a 40-pack year or more will.
  • Family predisposition – in other words it runs in your family. Obviously there’s precious little you can do about this one.
  • Occasionally a genetic condition called alpha 1 anti-trypsin deficiency.  This is uncommon but anyone with COPD symptoms aged less than 45 should be screened for this genetic disorder.

Diagnostic tests:

  • Key here is pulmonary function tests. The first test that must be done is the FEV1/FVC. In simple terms this test measures how much air you can force out of your lungs in 1 second compared to how much air you have in your lungs. In COPD this is below par, less than 0.7, and even with the best medicine available won’t get better.  Ever.
  • The test we use to see how bad your COPD is at any one time is the FEV1. In simple terms this test measures how much air you can forcefully blow out in one second. As COPD progresses this test goes from good to bad to worse to awful.

Finally, the most important thing to remember if you or a loved one has been diagnosed with COPD is this – COPD is very treatable and it’s never too late to stop smoking.


PS: Check out my article “Smoking Lives” for a quick look at how smoking impacts a family and a man, me.

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