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Peak Flow vs PFTs

K

Kristen

New member
I am a bit confused - yesterday I went to the allergist and they had my do PFTs and use a peak flow meter. I'm not very experienced using peak flow meters, so I don't know a lot about them. <br><br>My PFTs were good - FEV1 115%. However, my peak flow was not so good - according to the nurse, my peak flow should have been around 488 (for my age and height), and I could not get that thing above 400 for the life of me. Can anyone explain to me why this might be?<br>
 
K

Kristen

New member
I am a bit confused - yesterday I went to the allergist and they had my do PFTs and use a peak flow meter. I'm not very experienced using peak flow meters, so I don't know a lot about them. <br><br>My PFTs were good - FEV1 115%. However, my peak flow was not so good - according to the nurse, my peak flow should have been around 488 (for my age and height), and I could not get that thing above 400 for the life of me. Can anyone explain to me why this might be?<br>
 
K

Kristen

New member
I am a bit confused - yesterday I went to the allergist and they had my do PFTs and use a peak flow meter. I'm not very experienced using peak flow meters, so I don't know a lot about them. <br><br>My PFTs were good - FEV1 115%. However, my peak flow was not so good - according to the nurse, my peak flow should have been around 488 (for my age and height), and I could not get that thing above 400 for the life of me. Can anyone explain to me why this might be?<br>
 
H

Havoc

New member
Whereas peak flow and FEV1 are very similar, PFTs give you more information, FEV 25/75 for example. The difference may be from calibration of the machine, the calculation method used, or the scale used to measure what should be normal. I would give your clinic a call and ask how many L/min your FEV1 was and compare that to what you had on the peak flow at your allergist. If the numbers are similar, then you know. I would also stress to anybody that it's more important to look at the actual numbers rather than the % predicted on a PFT report.<br>
 
H

Havoc

New member
Whereas peak flow and FEV1 are very similar, PFTs give you more information, FEV 25/75 for example. The difference may be from calibration of the machine, the calculation method used, or the scale used to measure what should be normal. I would give your clinic a call and ask how many L/min your FEV1 was and compare that to what you had on the peak flow at your allergist. If the numbers are similar, then you know. I would also stress to anybody that it's more important to look at the actual numbers rather than the % predicted on a PFT report.<br>
 
H

Havoc

New member
Whereas peak flow and FEV1 are very similar, PFTs give you more information, FEV 25/75 for example. The difference may be from calibration of the machine, the calculation method used, or the scale used to measure what should be normal. I would give your clinic a call and ask how many L/min your FEV1 was and compare that to what you had on the peak flow at your allergist. If the numbers are similar, then you know. I would also stress to anybody that it's more important to look at the actual numbers rather than the % predicted on a PFT report.<br>
 
B

BreathinSteven

Guest
I agree with Havoc -- he generally seems to have well thought-out guidance and has a broad knowledge base...

My experience with peak-flow meters is that they are an inexpensive tool for measuring lung function -- they're generally plastic things and I found them rather easy to "game" -- with certain techniques, I could make them read much higher than they should have -- though that can probably be said for many devices... They might be a good guide if you use them consistently, but since I found them so easy to manipulate, I've never placed a lot of faith in them...

Also -- a full-blown Pulmonary Function Test in the PFT lab in a hospital or office can have substantially different readings than taking a PFT at home, or at your doctor's office... The smaller, portable units are often good for providing more information, as Havoc mentioned -- but they are more appropriate for showing trends than they are for accurate measurements... And, so many factors can come into play when you're using either a spirometer or a peak-flow meter... Beyond height and age, weight can quickly become an issue if you're overweight (not a problem for too many of us CFers -- but it can be -- and gaining some belly-fat can have a strong impact on my spirometry readings...)

Love, STeve
 
B

BreathinSteven

Guest
I agree with Havoc -- he generally seems to have well thought-out guidance and has a broad knowledge base...

My experience with peak-flow meters is that they are an inexpensive tool for measuring lung function -- they're generally plastic things and I found them rather easy to "game" -- with certain techniques, I could make them read much higher than they should have -- though that can probably be said for many devices... They might be a good guide if you use them consistently, but since I found them so easy to manipulate, I've never placed a lot of faith in them...

Also -- a full-blown Pulmonary Function Test in the PFT lab in a hospital or office can have substantially different readings than taking a PFT at home, or at your doctor's office... The smaller, portable units are often good for providing more information, as Havoc mentioned -- but they are more appropriate for showing trends than they are for accurate measurements... And, so many factors can come into play when you're using either a spirometer or a peak-flow meter... Beyond height and age, weight can quickly become an issue if you're overweight (not a problem for too many of us CFers -- but it can be -- and gaining some belly-fat can have a strong impact on my spirometry readings...)

Love, STeve
 
B

BreathinSteven

Guest
I agree with Havoc -- he generally seems to have well thought-out guidance and has a broad knowledge base...

My experience with peak-flow meters is that they are an inexpensive tool for measuring lung function -- they're generally plastic things and I found them rather easy to "game" -- with certain techniques, I could make them read much higher than they should have -- though that can probably be said for many devices... They might be a good guide if you use them consistently, but since I found them so easy to manipulate, I've never placed a lot of faith in them...

Also -- a full-blown Pulmonary Function Test in the PFT lab in a hospital or office can have substantially different readings than taking a PFT at home, or at your doctor's office... The smaller, portable units are often good for providing more information, as Havoc mentioned -- but they are more appropriate for showing trends than they are for accurate measurements... And, so many factors can come into play when you're using either a spirometer or a peak-flow meter... Beyond height and age, weight can quickly become an issue if you're overweight (not a problem for too many of us CFers -- but it can be -- and gaining some belly-fat can have a strong impact on my spirometry readings...)

Love, STeve
 
T

tesorotiffa

New member
I'm not sure, but my FEV1 is around 66% and my Peak Flow reading hovers between 450-480. I don't really know what the correlation is!
 
T

tesorotiffa

New member
I'm not sure, but my FEV1 is around 66% and my Peak Flow reading hovers between 450-480. I don't really know what the correlation is!
 
T

tesorotiffa

New member
I'm not sure, but my FEV1 is around 66% and my Peak Flow reading hovers between 450-480. I don't really know what the correlation is!
 
K

Kristen

New member
Thanks for the responses. I am definitely going to ask my CF doctor about it at my next clinic visit.

I found a spirometery print-out from about two years ago, and it says my FEV1 was 110%, but my FEF 25% was only 87% predicted (about 300 L/sec compared to the 400 L/sec I blow in the peak flow meter). Then my FEF goes up (in terms of % predicted) - FEF 50% was 91%, and FEF 75% was 138%. I'm not quite sure how this correlates to my FEV1 and Peak Flow, but it seems like I might have something going on when I first blow out.
 
K

Kristen

New member
Thanks for the responses. I am definitely going to ask my CF doctor about it at my next clinic visit.

I found a spirometery print-out from about two years ago, and it says my FEV1 was 110%, but my FEF 25% was only 87% predicted (about 300 L/sec compared to the 400 L/sec I blow in the peak flow meter). Then my FEF goes up (in terms of % predicted) - FEF 50% was 91%, and FEF 75% was 138%. I'm not quite sure how this correlates to my FEV1 and Peak Flow, but it seems like I might have something going on when I first blow out.
 
K

Kristen

New member
Thanks for the responses. I am definitely going to ask my CF doctor about it at my next clinic visit.

I found a spirometery print-out from about two years ago, and it says my FEV1 was 110%, but my FEF 25% was only 87% predicted (about 300 L/sec compared to the 400 L/sec I blow in the peak flow meter). Then my FEF goes up (in terms of % predicted) - FEF 50% was 91%, and FEF 75% was 138%. I'm not quite sure how this correlates to my FEV1 and Peak Flow, but it seems like I might have something going on when I first blow out.
 
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