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Now how do we diagnose COPD? Well we're going to get a really complete history of symptoms
from the patient. We might do some pulmonary function test that gives us specific numbers on
how well the patient's able to breathe. We also might look at a CAT scan or a chest x-ray. Now
how do we look at this progressive decline? Well we talked about pulmonary function test
now you see it in there with a clip on their nose and they have that mouthpiece in their mouth
and it's attached to a piece of equipment. So, a pulmonary function test, these are breathing
tests that they perform before and after a bronchodilator. So, they will do the test then they'll
give patient a bronchodilator that's inhaled and now they'll figure out if the airflow limitation
is present and/or partially or fully reversible. Remember that's a criteria we talked about
earlier. So, we're looking at pulmonary function test. You do them first then you give the
patient an inhaled bronchodilator then you measure again. That will help us know if the airflow
limitation is present and if it's partially or fully reversible with the bronchodilator. Now
spirometry measures the ratio of the amount of forced expiratory volume in 1 second and
that's forced vital capacity. So you divide the forced expiratory volume divided by the forced
vital capacity, that will give us a percentage. So that's what we're looking at, that percentage
number. So in a pulmonary function test, we're going to end up with that percentage that
gives us an indication of the patient's overall status. So, FEV divided by FVC gives us a
percentage. A baseline is important and then we consistently check in back with the patient
to see how they're progressing. Are they getting better or they go into that anticipated
progressive decline that we're trying to prevent. Now, a CAT scan or a chest x-ray are
2 examples of imaging that we use when diagnosing COPD. A chest x-ray will help us rule out
other diseases like maybe the patient has lung cancer or bronchiectasis, maybe pleural disease
or interstitial lung disease or even heart failure. So, this patient's having shortness of breath,
those are other things that we would consider as differential diagnosis and we want to rule
them out. Chest x-ray would help that. That also help us identify complications of COPD so we
want to make sure that do they have a pneumonia or not, do they have a pneumothorax and
air in there that has caused collapse of the lungs or then heart failure. So, chest x-ray can
help us rule out other causes or it might help us identify complications of COPD. You know
that some of the things are the same in both lists that's why it's never just a one test and we
know that's what it is. You have to look at all the pieces of information to put together the
puzzle to figure out the underlying cause of the patient's respiratory problems. Now, ABGs
and COPD, what would you expect? Well, usually you'll see a mild to moderate COPD, usually
shows moderate hypoxemia without any hypercapnia. Now if we didn't use those words, what
does hypoxemia mean? Hypo means low, emia is in the blood. So we're looking at ox in the
middle, that's oxygen. So low oxygen in the blood without hyperelevated capnia, meaning CO2.
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So with mild to moderate COPD, we normally see moderate low oxygen without elevated CO2.
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Now as COPD progresses, you're more likely to see an elevated CO2 level which we call
hypercapnia. Now, ABGs are often worse with an exacerbation, right, with exertion. So the
patient's just had a lot of activity then it's going to be worse if they've had an exacerbation
of COPD, those are also going to be worse. But it's always a good idea because ABGs only show
you what was going on at that exact moment that you drew that arterial blood gas sample,
that's what the ABG tells you. So good idea to look at trends. Do you have other values? Do
you have trends of before and after treatment? Those are critically important things to help
you put that whole puzzle together.