Why FEV 1 for Measurement?

[Blossom/Jackie W.]

I know this forun is still young with limited members but perhaps someone can answer this for me?

WHY do we (and the medical community) use our FEV1 numbers to measure or lung capacity? Especially since some folks have low FEV1's and aren't on oxygen, vs, some have higher FEV1's are are.

Is there a point to this?

Jackie NS

[filcab]

Hi Blossom,

We learn something new every day it seems. While reviewing your question, I found out that the medical community does not use FEV1 as a yardstick, but rather FEV1/FVC. The stages as developed by the GOLD standard are based on FEV1/FVC and not on FEV1 by itself. In my case my FEV1 is 10% but my FEV1/FVC is 21%. As we can only exhale 80% of our FVC max, FEV1/FVC is a more relevant number.

Our DLCO or diffusion rate can be a determinate as well as how well we can exchange gases at higher blood flows. These rates can also determine how quickly we can saturate.

The numbers are just used as benchmarks for the patient over time and how they compare to others, other factors aside.

Hope this helps,

Phil

[chrisw]

I really do hate to disagree with the administrator, but the GOLD guidelines define COPD as anyone whose FEV1/FVC ratio as less than 0.8 (or 80%) but they do use FEV1 as a measure of the severity. This is because it is the most defining of the amount of OBSTRUCTION.
www.goldcopd.com/GuidelinesResources.asp?l1=2&l2=0
However I do agree with Phil that this only measures how well you can get air in and out of the lungs and does not address whether your lungs can actually make use of the air you can move in and out. The diffusion capacity (DLCO) is a measure of how effective the lungs are at exchanging oxygen and carbon-dioxide. There is another measure coming into use called the BODE index - body-mass index (B), the degree of airflow obstruction (O) and functional dyspnea (D), and exercise capacity (E) as assessed by the six-minute– walk test. These variables were integrated into a multidimensional index which predicts likelihood of death from COPD.
I could give you a link to a calculator for the BODE index however the calculator has an error in it so it can give an incorrect and very depressing result!
Point is that FEV1 is only a part of the equation - probably the most critical thing is how well we use what we have left and that means keeping as fit as possible

[Blossom/Jackie W.]

Hmmmmmm; I'm generally up on the latest info and have all the latest guidelines etc though I am guilty of not reading EVERYTHING within. The reason I brought it up is that almost all COPDer's refer to their lung function with the FEV1 number as a more and easily defined mutual understanding of same.

Chris - as for the BODE; it might be interesting to see but if in fact it has errors in the caluculation....no thank you.

I had a form of BMI report done approx 6 months ago for a study I'm in (actually it was a bit of a different one; fat free body mass) and I keep meaning to seek out the interpretation of it. It included Fat% , Lean Kg, Total Body Water ltr., Est Metabolic Rate at rest in joules and Est Average Energy Required in ohms. (Does a Bodystat 1500 mean anything to you?)

[larrynz]

Funny thing is our Health Department uses FEV1 as a yardstick, as an example, to qualify for Spireva with a subsidy in NZ your FEV1 must be below 40%, over 40% you pay full price.

[Blossom/Jackie W.]

I know that in Canada we have something similar I'm sure for qualifying for "PharmaCare" or whatever the provincial plans call it; anyone know what the "qualifying" (for lack of a better word) is or even if there is one?

[chrisw]

I was going to reply that BC Pharmacare is based on income with different reimbursement depending both on drugs and income level. However on Googling it I found this site which gives information on drug coverage for all Canadian provinces:
www.drugcoverage.ca/p_benefit_bc.asp
ChrisW (on Vacation visiting granddaughters in Ottawa )
what DID we do for information BG (before Google!)

[Blossom/Jackie W.]

WOW!!! A GREAT find Chris. I know just the person who might be looking for that info.