Respiratory Pathophysiology 2

More stuff on COPD! Yup, as I said, this is pretty much all about COPD. Can't really blame the professor from focusing on it, though, as it is a pretty big deal.

Once again this lecture emphasised the link between smoking and COPD. Smoking is pretty much the #1 preventable risk factor for COPD. As a point of interest, COPD used be considered a "man's disease" because before it was mainly men who smoked. Now that women smoke as well, COPD has become more common in females than males.

The first step in dealing with COPD is identifying patients that might have it. This can be done simply by asking patients a series of questions about whether they cough regularly, cough up phlegm, are short of breath, wheeze when they exert themselves or get frequent colds. Questions like these should especially be asked if the patient has other risk factors, such as a history of smoking or older than around 40 years old.

The next step in a patient identified as being at risk of COPD is testing. The main type of testing is spirometry. I'm not going to go into detail about spirometry and all of the different lung volumes, as you can read about them in an earlier post of mine. The most important new fact here is that if a patient has an FEV₁/FVC ratio of less than 0.7 after giving them a bronchodilator, then they're likely to have COPD.

The last thing you need to know here is the pattern of lung volume changes in restrictive and obstructive disease.

Restrictive disease is pretty much the opposite of obstructive disease. In restrictive disease, air can't get in. Hence all of the key lung volumes, including residual volume, functional residual capacity and total lung capacity, decrease.

In obstructive disease, as we have seen, air struggles to get out. In early stages, air trapping occurs. During air trapping, residual volume and functional residual capacity increase since the air is not being exhaled out. However, total lung capacity remains the same as a healthy individual, resulting in a smaller vital capacity (difference between total lung capacity and residual volume). If COPD progresses further, however, the body may try to compensate by increasing the total lung capacity in what is known as hyperinflation. Unfortunately, this can never completely compensate for the loss in vital capacity during COPD.