Pulmonary Function Test (PFT) Explained Clearly – Procedure, Spirometry, FEV1
03
October

By Adem Lewis / in , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , /


kram welcome to another MedCram
lecture we’re going to talk about pulmonary function testing and this is
going to be over a couple of lectures we’re going to go over the introduction
and give you a little bit of a primer if you will on pulmonary function testing
and then get into more specifics so that you understand exactly what it is it’s
going on so the whole point of pulmonary function testing is to measure someone’s
lungs and find out whether or not they’re normal or abnormal and if it’s
abnormal find out why now this is kind of akin to getting tests on for instance
your heart with an echocardiogram or an EKG where we’re measuring the heart well
the problem is that the heart is measured on a proportion for instance
the ejection fraction is how much blood on each pump the heart can pump out and
normal is you know approximately 50% ejection fraction and we can measure the
chamber size and we can measure the valve and see if there’s regurgitation
the problem is in taking this issue and taking it over to the lungs is that the
lungs are more of an absolute and people’s lungs can be different based on
their height and other variables so we need to figure out exactly how
we’re going to figure out what’s normal for somebody’s lung and that can be a
little tricky so are there four things that we need to take into consideration
before we determine what the absolute values are for somebody who can do a
pulmonary function test and the first one is height okay so height makes a
difference let me explain you’ve got somebody here who is very
tall versus somebody who is very short obviously a proportion of their body is
going to have lungs in them and the short person is going to have smaller
lungs and the bigger person is going to have bigger lungs and so obviously the
amount of air absolutely they could be able to breathe in
out is going to be dependent on the size of their lungs so obviously height has
to come into it so that’s the first thing with it we’re going to need to
know and put into our equation to figure out what the normal lung volume should
be for somebody number two is going to be age what happens as you hit the age
of 25 which is the best that you’re ever going to be in life in terms of your
lung function is lung function generally is going to decline even if someone has
never smoked and so as you get older the lung function is going to decline and
depending where you are along that axis that x-axis is going to determine where
somebody would be normally for any point along that curve and so age is the
second variable that goes into the equation the third variable is gender
okay male and female are going to have different sized lungs and so that needs
to be taken into consideration this is independent by the way of height so
gender is the third variable that goes into that and number four is race let me
give an example if you’ve got four for sake of argument here you’ve got a white
man and african-american black man in terms of where their proportions are
generally speaking the white man is going to have his waist or his navel if
you will lower down then an african-american or the black man it
should be higher so given the same exact height black man is going to have
smaller lungs than would white and similarly you could look at the
other way that black men would have longer legs for a specific height then a
white man who would have shorter legs and this has been looked at and
researched in in the literature and so as a result race also needs to play a
role in terms of if you have someone with a specific height they’re going to
have different sized lungs based on proportionality okay so the purpose of
all of this is to come up with a customized value for each individual
based on hundreds and thousands of patients and research and distributions
and curves and things of that nature so if you put a specific human being
okay and the four variables number one is height number two is age number three
is gender and number four is race and you take all of these variables of a
person and you put it into the computer and turn a crank outcomes values x in
this case and it’s that number that’ll tell you what the normal distribution
should be so there’s going to be a distribution of patients and it will
tell you what the eighty percent limit is that number there will tell you if
you are below this number okay actually it will be down on this side here eighty
percent here if you are below this number that means you are abnormal these
are all normal patients here okay and if you are below the 80% of predicted of
that value then that means you are abnormal let me tell it to a different
way let’s say we plug in those four values and we come up with a number for
the forced vital capacity and we’ll get into these numbers
a little bit and let’s say that the number they come up with for the forced
vital capacity for argument’s sake is three point zero zero liters that means
that the 80th or the minimum 80th percent for three litres or eighty
percent if that predicted is going to be 2.4 liters and so if you are below 2.4
liters that is considered abnormal another way of saying it is that if your
value is greater than 80% of the predicted then you are normal and
there’s no problems okay so the key I want you to get out of this lecture is
specifically the lungs are a organ of the body the organ of the body that can
change in size and you can get different values for different people all with
different distributions based on the four criteria which is
height number two is age number three is gender and number four is race once you
take an individual and you plug those numbers into the computer they will give
you values and it’s those values that you must base your abnormals on this is
different than looking at blood tests for the liver or looking at an
echocardiogram for the heart because in that situation there really you don’t
really have to take into consideration these values so in our next lecture
we’re going to talk about the lung itself and the pathophysiology but this
is kind of an introduction so join us for the next lecture thanks very much you


69 thoughts on “Pulmonary Function Test (PFT) Explained Clearly – Procedure, Spirometry, FEV1

  1. It would be great if you could do a video about reading ECGs. It's hard to find someone who makes this subject easy. Thank you for your videos, they're very helpful!

  2. Not complaining that there are three parts… Just wondering what was going on.. Haven't watched the videos yet but I ve watched other videos on your channel an they re great!!!

  3. Your lectures are really nice. I am working at hospital as a nurse in Korea.These day I always study your youTube. It is very fun. I understand about disease easily. Thank you so much.

  4. ❤️thank you so much, I've watched all five videos and they are incredible… Great job making them, glad to step upon them ❤️

  5. Thank you so much for these videos; specifically "Chronic Cough, PFT etc. I've experienced almost annual Bronchial Pneumonia or Bronchitis and chronic coughing lasting 3 – 4 months. 2 prescriptions of Antibiotics this year (Jan. Mar. 2015), I am resisting family pressure and the traditional medicine approach to go for a third. I've joined a private clinic which practices an integrated medicine approach and we're investigating the 3 pronged causality outlined in your Chronic Cough video. I, at last, have hope.
    Thank you again.

  6. Beautiful explanations: better than my med school physio professor. By the way what software are you using? It just looks cool. Please do more of this because you have an excellent/logical way of explaining things.

  7. See the whole series at www.medcram.com along with other top quality videos including reviews in pulmonary, cardiology, infectious disease, and hematology!

  8. This explanation of the FEV is excellent. You explained my lung capacity better than my specialty VA medical professional.

  9. you might be extremely knowledgable about medical topics but you don't "turn a crank" to power a computer

  10. Hi Dr Roger good day to you I'm working on a project which requires me to do spirometry test on individuals exposed to cement dust and make conclusions. However my spirometer only gives the PEF and FEV1 values . Please tell me how I can use these values to make conclusions and any health problems with the test subjects. Please I really need your help .

  11. These test can be Very Emotional. Check out encourageyourselfcom.blog to see more about Karen's journey with Pulmonary Hypertension

  12. Thank you for making this video. I am studying medicine in country where english is not their native language. They promise to teach in english but it’s not 😔 so again, thank you finally i understand about this

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