I have a new pulmonary arterial venous malformation (PAVM) and I have read this can increase DLCO results on the PFT. In August 2016 my DLCO was 17%. By October 2016 it was 27%. In March 2017 it was 38%. In October 2017, a chest CT showed the PAVM. Can the PAVM be the reason for this drastic increase in DLCO? The odd thing is I am actually requiring more oxygen when walking (3-4 LPM) instead of using less. So if I am improving, why do I need more oxygen instead of less?

Response: PAVM usually causes a decrease in DLCO and hypoxia due to Right-to-Left (venous to arterial) shunting, although this only tends to occur in severe cases.  A decrease in shunting could cause DLCO to increase but should also decrease your hypoxia and your need for supplemental O2.  For this reason I don’t think the PAVM is the primary reason for the changes in DLCO but I’m a technologist and this is far from my area of expertise. It is clear that there is something complex going on with you and the questions you are asking should really be addressed to a pulmonary physician.

Hello, Appreciate if you could share your thoughts below – Diagnosed with costochondritis in 2008. Chronic and continuous chest pain and Shortness of breath over last many years. What has changed- Intensity/episodes of pain much less for last 1.5 years. However persistent (daily) and chronic shortness of breath (without exertion). SoB stays for hours and sometimes days. No change in SoB with exertion – in fact feel better while active (including sports). No whizzing, no cough/ mucus. Tightness/pain in chest while breathing. SOB seems to be getting worse. Heart EKG, Echo and Stress test, blood work, normal. Recent chest CT scans (2016 and 2017) normal. working diagnosis of obstructive pulmonary disease. however doctors unsure given chronic and persistent nature of SOB, inhaler medication doesn’t work and no definite asthma symptoms (no wheezing/coughing). also no change in FEV1 with bronchodilator during PFT and DLCO low (72% predicted). Results from PFT tests (2014, 2017 march, 2017 nov)

  • FEV1 – 79%, 74%, 77% (all predicted)
  • FVC – 84%, 82%, 90% (all predicted)
  • FEV1/FVC – 77%, 71%, 69%
  • TLC – 87%, 95%, 88% (all predicted)
  • RV – 100%, 86%, 84% (all predicted)
  • DLCO – 72%, 80%, 72% (all predicted)
  • DLCO/VA – 92%, 82%, 82%

result from bronchochallenge test (dec 16) – 29% reduction in fev1 at25 mg/ml what is likely diagnosis? is this SOB related to costochondritis? or is this related to lung? or is it both? if it is related to lung is it obstructive (asthma or COPD) or restrictive? or is this early inset of ILD given low DLCO? what further tests (blood, PFT, CT) should be done to confirm diagnosis? how frequently should the tests be repeated going forward? Thanks much in advance

Response:  Please remember that I’m a technologist, and not a physician.  I’m qualified to discuss test quality and physiology, but the questions you are asking should really be addressed to a physician.  

Having said that all of your tests show mild airway obstruction with normal lung volumes.  The 2014 and Nov 2017 results also show a mild gas exchange defect.  I am sorry to say that these test results are not anywhere near abnormal enough to explain your shortness of breath, nor for that matter, does your costochondritis.  The costochondritis by itself however, could easily explain your chest pain since that is a common complaint.

A diagnosis of asthma has a low probability given your lack of response to bronchodilator and in addition a low DLCO is not usually seen with asthma.  You did have significant bronchoconstriction during the bronchochallenge test but if it was a methacholine challenge (and not mannitol) the 25 mg/ml dose is very high and puts you in the normal range.  

ILD also has a low probability and that’s because your TLC and FVC are within normal limits and have not changed significantly in 3 years.

COPD is a possibility, but you don’t mention any history of smoking or any occupational exposures so it’s hard to say how likely that really is.

I am speculating here, but costochondritis makes it painful to take a deep breath in, so for that reason I have to wonder if you are hypoventilating (not breathing enough) and in particular, if you are not taking what’s called a “sigh breath” regularly.  Whether they realize it or not, everybody takes an extra deep breath (sigh breath) every minute or so.  A sigh breath helps to re-expand your lung and prevents atelectasis (collapse of the lung tissue).  When you exercise you probably breath more often and more deeply and that may well be why you feel better when you exercise than you do when you are just sitting around.

For your peace of mind, I’d suggest that you have spirometry and a DLCO test a least once a year for the next several years.  If there is a trend in any particular direction, that should be enough to detect it.

My test results are-
FEVI of 1.98L (60% of predicted)
forced vital capacity of 69%
ratio of FEVI over forced vital capacity was 77%
total lung capacity 104%

I am a 72 (73 in Feb.) year old male about 5’6′ and 160lb
I walk my dog 2 miles every morning, lead a very active life and do 30 minutes on the treadmill every other evening
*what is your interpretation of these results?
Thank you VERY much

Response:  Your spirometry results show moderate airway obstruction.  Your normal TLC says that your FVC is likely reduced because of the airway obstruction (you just can’t blow out long enough).

I have been short of breath at rest and increased with exertion for months. CBC, CXR, EKG have been normal. My PFT was normal except for the DLCO was at 134% predicted. What are some things that this result could indicate?

Response:  A DLCO that is 134% of predicted is not particularly abnormal.  An elevated DLCO is seen commonly in individuals with asthma or who are obese.  It can also be due to which reference equations are being used.

Hi. I’m 37, been told I have mild copd, cannot understand numbers. No symptoms. Please help!

Base 3.74, %Pr101, predicted 3.70,Post 3.83,%pred104.
FEV1/FVC Base 79, predicted 81.post 79.

Response:  Your spirometry results are normal so I am not sure why you were told that you have COPD.  You didn’t have a significant change in your results after the bronchodilator, but given that the baseline results are normal in the first place that’s not a real surprise.

Hi, I have had about 3 Pulmonary Function tests done for shortness of Breath on exercise over the past couple of years. All the Diffusing Capacity results are moderately reduced of predicted % of DLCO but the rest of Spirometry is normal in all 3 tests. I have not been a smoker for over 50 years and when I smoked as a young person it was only for about 6 months. The first DLCO was 55% and DL/Adj 54% The second a little more reduced and the third one was down to 49% and 48% adjusted. I was told this was only a mild reduction but that is not what I have read on “Up to date” and other medical reports on the DLCO. I have what seems to be increasing shortness of breath on exercise but because high resolution CT Scan, Echocardiogram and finally a right Heart Cath did not show any obvious signs of disease no one seems concerned about my shortness of breath or my lowering DLCO. I occasionally have some desaturation on exercise which I tried to measure myself with finger pulse oximtery, but usually its reasonable, 95 – 97 until I finish exercise and then at rest the O2 sats will sometimes drop to about 91-93. I don’t understand what all this means. For a period of time the shortness of breath on exercise seemed to improve but then I had a Procedure for another medical condition and had the complication of a small bowel perforation with fluid collections and some lung issues. This resolved with conservative treatment, not surgery, but I am now much more short of breath on exercise again and also get easily exhausted, and weak. The Bowel Perforation was about 5 months ago. Would like to understand what is happening to me and why my DLCO is abnormal and seems to be getting worse.

Response:  I’m a little unclear about some of the information you’ve presented.  If your physician was saying that a decrease in DLCO from 55% to 49% is only a mild decrease, then I would agree.  On the other hand, if they were referring to a DLCO of around 50% of predicted as only mildly reduced, then I would disagree and say that according to the ATS/ERS standards that would be moderately reduced, and in either case worth some degree of concern.  

In addition you said that your DL/Adj was 54% and 48%.  Can you say whether the Adj(ustment) was for hemoglobin or for alveolar volume (VA)?  

You said your spirometry was normal but not whether you’ve had your lung volumes measured.  Although it’s is somewhat uncommon it is possible for some people with a restrictive lung disease to have normal spirometry but a reduced TLC.  I’m not in any way suggesting you have something like Sarcoidosis or Pulmonary Fibrosis but without that additional piece of information it is hard to differentiate between possible causes of a reduced DLCO.

Realistically, with a DLCO around 50% of predicted I’m surprised that your SaO2 isn’t dropping when you exercise, but the reasons that sometimes happens after you stop are likely complicated (possibly O2 debt versus ventilatory drive) but aren’t likely concerning.  I’m sorry to hear about the complications you had from the procedure but recovering from what are likely fairly serious complications could by itself make you short of breath regardless of what your lung function is like.

I been a occasional smoker and in the year 2016 i smoked a lot due to stress and i quit smoking from December 2016. after april 2017, i started getting shortness of breath, chest pain, gastric problem, LEX LES, When i went to doctor for 1st time, My FEV1 is 92% and FEF2575 is 66%. and i have been given a puff tool to take Foracart 200 cipla every day morning 8am and 8pm. after 3 months, FEV1 is 95% and FEF2575 is 79%. My question is, am i in serious issue? Do i have cancer or something ? My CT scan says Hyperinflated lungs. Please advice..

Response:  First and most importantly, there are no pulmonary function tests that can tell you whether or not you have lung cancer. That is what chest X-rays and CT scans are for.

At worst you may have mild airway obstruction, but that isn’t clear without knowing what your FEV1/FVC ratio is.  The change in FEV1 after 3 months is not significant and the FEF25-75 is not a useful measurement (really!).  

In order to confirm the CT scan’s finding of hyperinflation you need to have your lung volumes measured (either by plethysmography, helium dilution or N2 washout). Hyperinflation usually only occurs in the presence of severe airway obstruction (which you do not have) and only over many years.  It is more likely that you just have larger than normal lungs.

A diffusing capacity (DLCO) test would actually be most helpful in determining whether your lungs have been damaged by the cigarette smoking.  I would suggest that you ask your physician to order a more complete set of pulmonary function tests for you.

FVC % predict 89 FEV1 81 FEF 25/75 64 FEV1/FEC 71 Normal? Thoughts. Thank you.

Response:  By themselves both your FVC and FEV1 are within normal limits.  The FEV1/FVC ratio is what’s used to determine if you have airway obstruction but there is some disagreement among pulmonary physicians about where the threshold for a normal FEV1/FVC ratio lies.  Some consider that an FEV1/FVC ratio less than 95% of predicted indicates airway obstruction and by this criteria you would be considered have mild airway obstruction (FYI: the FEV1/FVC you reported is the actual ratio, not the percent predicted).

Some physicians however, consider the Lower Limit of Normal (which is approximately 89% of predicted depending on which reference equations you use) to be the threshold, and by this criteria your results are within normal limits.

My personal belief is that the truth is somewhere between these two thresholds.  I think that 95% of predicted for the FEV1/FVC ratio tends to overdiagnose the number of elderly individuals (60+) with airway obstruction but that the Lower Limit of Normal tends to underdiagnose airway obstruction in the young (20-40).

2013 Results: FVC – 91

FEV1 -88
FEV1% – 98
FEF25-75 – 79
PEF – 80

2017 Results
FVC – 78
FEV1 – 83
FEV1% – 105
PEF – 61

Response:  The 2013 results are within normal limits.  At first glance the 2017 results suggest a reduced lung volume (restriction) but this could only be determined from lung volume measurements.

The major problem with diagnosing lung restriction from spirometry results alone is that about 5%-10% of people with asthma have an FVC that is lower than their FEV1 but this is due to a type of air trapping from their airway obstruction and not from a reduced lung volume.

I have fvc,3.06 65%,,,

fev1 1.52 41%,fev3 2.36 55%,Delco 23.1 82% ,,,,are these bad numbers

Response:  Your reduced FEV1 suggests that you have severe airway obstruction.  The normal DLCO indicates that this is probably something more like asthma than like COPD.  

The reduced FVC may be due to the airway obstruction (you can’t blow out long enough) but a reduced lung volume (restriction) is also possible.  The only way to know would be to have your lung volumes measured.

My 87 yr old mom has been having shortness of breath…

mostly upon exertion for about 6-9 months with it gradually gettin worse. Spiro results in July,2017 FVC 100% of pred, FEV1 71% of pred, FEV1/FVC 71%. Had a full pulmonary function test yesterday with results of: FEV1 1.31 @ 115%, FVC 2.25 @ 142%, FEV1/FVC 58 pred @ 80%, TLC 124, RV 122……Unable to obtain lung vol and diffusing capacity due to patient having adverse reaction to testing…. became extremely short of breath, started shivering, felt very cold, headache started, just didn’t feel right. BP was 95/60. It took about 15 minutes for my mom to begin to feel a bit better and to start breathing better. Doctor came in and said everything on test was normal and she couldn’t explain her reaction. Discussed recent Chest CT scan with possible pulmonary fibrosis, some calcified nodules and some linear interesting markings. Put her on a course of Prednisone and said to come back in 6 weeks unless we need her sooner. Something just doesn’t feel right to me especially after witnessing what happened during her testing. What do her numbers say to you as well as the reaction she had during the testing? Thank you

Response:  The spirometry results from July show a mild airway obstruction (i.e. asthma, bronchitis or COPD). There appears to be significant improvement in the FULL results but there is still possibly some mild obstruction. The difference between these two sets of results could be due to a change in medications or, if they were performed in different locations, may be due to a change in reference values or an improvement in test quality.

You said that lung volumes could not be obtained but you also put in that the TLC was 124% of predicted which is mildly elevated (??).

Your mother’s symptoms during testing (shivering, cold, headache, low BP) are not in any way normal responses to pulmonary function testing and are most likely due to something else. Shortness of breath is more common however, and it’s too bad that she was unable to perform a DLCO test since that would have helped sort things out.

What results you’ve shared from the second set of tests, given that they’re fairly normal, isn’t really consistent with pulmonary fibrosis per se, but my lab sees a number of patients with pulmonary fibrosis who have normal-ish spirometry.

Unfortunately, shortness of breath is a non-specific symptom and can have numerous causes, many of which have nothing to do with the lung. The fact that your mother’s spirometry results appear to be highly variable makes me a bit suspicious about test quality. I would be happier if there DLCO or oximetry results since that would help make the overall picture clearer.

I’m coughing mucus sometime with blood

for a year hrct [High Resolution Cat Scan] normal bronchoscopy normal Spirometry jan 17 Fvc 5.24 112% Fev1 4.80 105% Dlco 94% Spirometry aug 17 Fvc 4.80 98% Fev1 4.00 97% Dlco 104% I don’t have a clear diagnostic my dr belive i may have a prolonged infection

Response:  Although both spirometry tests are probably within normal limits you had a significant decrease in FEV1 between January and August (-17%). This isn’t as apparent as it should be since the predicted FEV1 (and FVC) are different for the two tests.  In January the predicted FEV1 was somewhere around 4.57 L and in August it was around 4.12 L so you either had your tests at two different places or they changed reference equations in between.

A decrease in FEV1 like that could be a concern but some people are normally variable, or it could be a difference between testing systems or it actually could indicate a trend.  You won’t know for sure until you are tested again.  At the moment however, your August results, which includes your DLCO, are within normal limits so I wouldn’t be overly concerned about it at this time.

A chronic cough is, unfortunately, a non-specific symptom.  It can be due to a wide variety of lung disorders but just as often it is due to allergies or environmental causes.  Frequent or violent coughing can also cause hemorrhaging of the blood vessels in the airways so the blood in your sputum may be due to the cough and not to an underlying lung disorder.  

It is possible you have a lung infection but these are often difficult to diagnose since there are a wide variety of bacterial, fungal and viral causes.  I’m not up to date on diagnosing lung infections (not my area of expertise anyway) but having your sputum cultured for organisms used to be a relatively common practice.  It would be best if you talked to your physician about this.

Would you be so kind and explain my lung function results:

During a hospital stay in November 2015 my hand held spiromentry showed – FEV1/FVC = 73%, FEV1 = 1.57 (64%), FVC = 2.14 (74%). During May 2016 my lung function tests showed normal spirometry with an FEV1 of 91% and an FVC of 97% my TLCO was reduced to 65% and the KCO at 76% . Thank you so very much. Kind regards. 

Response: Your first set of tests would be interpreted as showing moderate airway obstruction (such as asthma or COPD). The second set shows reasonably normal spirometry without any significant airway obstruction but the decreased TLCO (DLCO in the US) shows a mild gas exchange defect (your lungs aren’t working as well at getting oxygen into your blood stream as they ought to).

The increase in FVC and FEV1 between your first and your second set of tests isn’t uncommon, particularly since you were hospitalized for the first set.  You mentioned that your first spirometry test was performed with a hand-held spirometer so I’m going to guess it was done in your hospital room.  A factor that may contribute to somewhat lower FVC and FEV1 readings would be if you did the test while in bed. If it was possible they should have had you sit on the side of the bed but if you were lying down in anyway that would cause your test results to be up to 10% lower than they would be otherwise.

Even though your test results did improve over time they do show that you have some form of airway obstruction. Although this, along with the reduced TLCO, could suggest mild COPD, realistically that has to be complete speculation because there are many causes of a reduced TLCO (including testing issues) and they may not have anything to do with each other. 

I was diagnosed with ild last year…

…waiting on explanation of lung biopsy results that show mixed rbild, nsip and early uip pattern. My last pfts show fev1 of 2.56 90% predicted, fvc 3.17 95% predicted with ratio 81 and tlco of 3.28 54% predicted. I’m guessing the fev1 and fvc are not too bad but concerned about tlco, what does this mean and is 54% something to worry about?

Response:  Lung volumes (FVC and TLC) are usually decreased when interstitial lung diseases (ILD) are present but this is not a given.  Your spirometry results (FVC and FEV1) are reasonably normal but a TLCO (DLCO) that is 54% of predicted is moderately reduced.  When gas exchange is this low it can indicate that you might need supplemental O2. Some forms of ILD respond to steroids and other medications; many, unfortunately, do not.

FVC 122 DLCO 59, KCO 63

Response:  Your FVC is elevated, which makes it an outlier phyiologically speaking, but is not clinically abnormal.  It also suggests that your overall lung volume is probably normal.

Your DLCO and KCO are both reduced, however.  Some important information you did not include was your FEV1 and FEV1/FVC ratio.  DLCO is often reduced when the FEV1 and FEV1/FVC ratio are reduced (think COPD).  If your FEV1 and FEV1/FVC ratio are normal, then the reason for a reduced DLCO is probably something more like pulmonary vascular disease (which can include a pulmonary emboli).

Another possibility is that the DLCO test quality may be low. This can be partially assessed by your inspired volume from the DLCO test.  The inspired volume should be at least 85% of your FVC.  If the inspired volume is signicantly lower than that then the DLCO may be underestimated.

Would these results be normal?

Fev1/Fvc ratio 79,  Fev1 101%, fev 95%, tlc 95% , rv 94%, rv/tlc 37. Dlco 70% dl/va 101%.

Response:  The spirometry results (FEV1/FVC ratio, FEV1, and I assume you meant FVC instead of ‘fev’) and lung volume results (TLC and RV/TLC) look normal.

At 70% of predicted your DLCO is mildly reduced which could indicate that you have a problem with gas exchange (getting oxygen in and carbon dioxide out).  I do have some reservations about your DLCO test quality however. Specifically, given that your DLCO was 70% of predicted the DL/VA of 101% means that the VA was also reduced to about 70% of predicted.  VA is expected to be approximately equal to your TLC, which was 95% of predicted.  This most likely means that your inspired volume (the amount of air you breathed in before you held your breath) was probably less than it should have been.  This could mean that your DLCO was reduced because of poor test quality and not because you really have a problem with gas exchange but without seeing the raw data from your DLCO test this can only be speculation on my part.

My mom recently found out her DLCO was at 31%.

She was diagnosed with Emphysema a month or so ago and we are trying to figure this out as we go along. My question is, what is the significance of a low DLCO when Emphysema is the diagnosis? Can this improve with rehabilitation? 

Response:  Emphysema is a disease both of the airways and of the alveoli.  There is usually a correlation between these two things and because spirometry is a quick and simple test it tends to be the most commonly performed for individuals with COPD and Emphysema.  A spirometry test can only measure airway function however, and a DLCO test measures how well the alveoli are functioning.  Since the alveoli are where gases (oxygen and carbon dioxide) are exchanged in the lung a low DLCO means that the your Mom’s alveoli aren’t working very well.

When DLCO is reduced because of emphysema it usually doesn’t get any better.  What rehabilitation will do however, is to train people ways to deal with their lung disease (it’s not just for Emphysema) which includes breathing techniques, diet and learning how to pace yourself.  There’s also the fact that when anybody has trouble with their breathing they tend to do less and less over time, and this leads to physical debility. Rehabilitation gets individuals to exercise again which helps to re-build muscles and allows them to make better use of what they have.

You did not mention supplemental oxygen, and for a DLCO that low it is likely your Mom will need it.  Most patients will probably say that supplemental oxygen is a pain to deal with but my experience is that it measurably improves the quality of life and is worth the extra effort.

My DLCO was 70%

and I have mild pulmonic insufficiency. Is this something to worry about?

Response:  Pulmonic insufficiency refers to the ability of the right side of the heart to pump blood.  Venous blood returns from the body and is pumped first through the lungs by the right side of the heart and then is pumped through the body by the left side of the heart.  

It’s possible the DLCO is reduced simply because there isn’t as much blood being pumped into the lung as there should be. If this is the case then gravity would cause the lower parts of the lung to have a lot more blood than the upper parts of the lung.  This is a ventilation-perfusion mismatch and you would need a special test (V-Q scan) to show if this is happening or not.  

There are no simple answers however and this is because the interaction between the heart and the lungs is very complicated and cause-and-effect can be difficult to determine.  I would recommend that you see a pulmonologist or cardiologist that specializes in pulmonary circulation.

I am 57 yr old female smoker what does this mean?

DL/VA is 69 DLCO is 54 Spirometer is normal

Response:  DLCO is a measure of the lung’s gas exchange efficiency and a DLCO that is 54% of predicted that this is moderately reduced.  By itself a reduced DLCO cannot say whether or not it was a result of smoking. The fact that your spirometry is normal could suggest that the cause of the reduced DLCO is due to something else since the FEV1 and FEV1/FVC ratio are also usually decreased when a DLCO is reduced because of COPD.

How much you smoke and how recently you smoked before having a DLCO test can affect your DLCO results.  A recent cigarette (within 15-30 minuted of testing) will cause you to have elevated levels of carbon monoxide in your lung. Because the DLCO test is essentially a measurement of carbon monoxide uptake, an elevated level of carbon monoxide in your lung from a cigarette will make it look like your uptake rate is lower than it really is and will therefore lower your measured DLCO.  

In addition, if you are a regular smoker you will have an elevated level of carboxyhemoglobin in your blood. Carboxyhemoglobin is hemoglobin that is bound to carbon monoxide rather than oxygen and when this happens that hemoglobin is not available to bind either with oxygen (which is why you can die from carbon monoxide poisoning) or with any of the carbon monoxide used in the DLCO test.  An elevated carboxyhemoglobin level will therefore also act to reduce your measured DLCO.

Regardless of the reason your DLCO is reduced, continuing to smoke is not a good idea.  I’m sure you already know this, and I know how difficult it can be to quit.  Please try, though. You’re not alone and there are many resources out there for anybody that wants to quit.  Talking to your physician is a good starting point.

Final note; the DL/VA is not a useful value for you so it can be ignored.

Hope you can answer some questions…..I’m TERRIFIED OF COPD

….mainly because my father died of complications from same….at 70!!…..I have taken the test for Antitrypsin…..it was negative….but am still worried….embarrassed to say that I am still smoking (less than 1/2 a pack a day….but I know….) If you could interpret my values that would be amazing…..my PCP is great, but not a specialist, obviously…..here are results from 2015 battery of PFT’s and those from last week….

2015 2017
Pre, %Pred: Post-BD, %Pred: Pre, %Pred: Post-BD, %Pred:
FVC 124% 128% 108% 114%
FEV1 105% 108% 88% 93%
FEV1/FVC 67% 65%
TLC 124% 133%
RV 121% 179%
RV/TLC 32% 45%
DLCO 83% 86%
DL/VA 78% 78%

Impressions 2015….. “Spirometry reveals mild airway obstruction”; “Lung volumes are normal”; “Diffusing capacity is normal”; “No significant response to bronchodilator” Impressions 2017… “Spirometry reveals mild airway obstruction”; “Lung volumes suggest minimal HYPERINFLATION”……YIKES…. “Diffusing capacity is normal”; “Minimal response to bronchodilator”. i am alarmed by the 2017 RV value!!…..”179″ seems frightening! ….any feedback you can give me would be welcome…..I am a 61 year old male, 5’6″, 155 lbs……I am in good health (low cholesterol, low BP, low A1C, etc.)…..I run 15-20 miles per week, and post-excercise pulse ox/resting is always 95-97….up to now, at least, I have no breathing difficulties at all…. PLEASE, wise one!…..give me a reading here! Thank you so much!

Response:  You have an elevated FVC and a normal FEV1 and this causes a low FEV1/FVC ratio.  Although a low FEV1/FVC ratio is usually considered to be a sign of airway obstruction it may be a sign of something that’s called dysnaptic growth instead.  Dysnaptic growth is where during childhood development the lung tissue volume (FVC) is higher than airway diameter (FEV1). To some degree this is seconded by your elevated TLC. Yes, TLC can be elevated in end-stage COPD, but your 2015 RV is normal and that makes this look a lot more like dysnaptic growth that gas trapping and hyperinflation (your 2017 RV is elevated but this is far more likely due to a testing error).  For these reasons and considering that your FEV1 is normal I find it hard to be terribly concerned about your FEV1/FVC ratio.  In addition your DLCO is normal (ignore the DL/VA, it is relatively meaningless in this situation).  

You have had a significant decrease in FEV1 from 2015 to 2017 but this could be due to a couple different reasons.  First it’s possible that the lab you had the tests performed at has changed which reference equations it uses during that time interval.  You need to look at the change in the actual test values to know if this change is real or due to something like this.

Second, FEV1 doesn’t usually change this quickly because of COPD.  Yes, FEV1 decreases faster in somebody with COPD than somebody without COPD, but if the change is real then it could be due to equipment problems or you could have bronchitis or asthma (and simply because there wasn’t a big change in FEV1 between pre- and post-BD tests doesn’t mean you can’t have asthma).

I think it is unlikely that you have COPD.  Your results look more like a combination of dysnaptic growth and possibly asthma or bronchitis. COPD is most often a self-inflicted disease caused by smoking (although it can also caused by an Alpha-1 Antitrypsin deficiency).  Assuming you don’t smoke (you didn’t say although it is unlikely given the distances you can run) then your risk for it is slight at best.

I have received copies of PFT testing and was hoping that you would be able to shed some light on the numbers.

I am a 54 year old white female who is 5’5″ and my weight fluctuates but at the time of testing I was 163. Spirometry: Pre Med = FVC 59% and FEV1 of 49% Post Med = FVC 64% and FEV1 of 48% DLCO: 1. 28.4 2. 27.4 I do have copies of all the other #’s of the Spirometry and DLCO testing if needed for further input from you. And so based off of these test results I was told I have “Severe Obstruction” COPD / Asthma (Due to remodeling)?

Response:  Your spirometry results show severe airway obstruction.  Your DLCO is normal, however, and this argues against a diagnosis of COPD.  Chronic asthma can lead to what’s called airway re-modeling, which causes a more or less permanent decrease in airway diameter.  The fact that your FEV1 did not change after inhaling a bronchodilator would tend to agree with the idea of airway remodeling but asthma can also have an inflammatory component which also causes airways to narrow and can be treated to some extent with inhaled steroids.  The only way to find out would be to go on inhaled steroids for a reasonable period of time (at least a couple months) and have your spirometry performed again. You’d have to do this with the assistance and agreement from your physician, however.

Your reduced FVC is probably due to gas trapping (i.e. not being able to blow out long enough to completely empty your lungs) because of your airway obstruction, but without actually measuring your lung volumes it’s not possible to rule out co-existing restriction (reduced lung capacity).

I am 33 years old..

is fev1/fvc 83% normal.  I am hacking up brown mucus for 6 month..what does it mean?

Response:  If you mean the actual FEV1/FVC ratio is 0.83 then yes, that is probably normal.  If you’re asking if an FEV1/FVC ratio that is 83% of predicted is normal, then no it isn’t.  

You need to see a physician about the mucus you’re coughing up.  There are many possible reasons for ranging from chronic bronchitis to a nasal infection and only a physician will be able to tell you what’s causing it.

I am a 54 yr. old white female who was diagnosed with “asthma”

about 5 years ago after a trip to the E.R. due to shortness of breath, wheezing, etc. I have been always prone to “bronchitis” due to being an allergy sufferer or so I was told.

Last year I was hospitalized prompted by a call to 911 and transported to hospital via ambulance due to being unable to breathe.  I was hospitalized for 4 days due to another bad bout of bronchitis – however now I am being told that I have COPD and Asthma from testing that was done at hospital and doctors office.

I am being sent to have a DLCO done  by the Social Security Disability determination board. They recently sent me for a Spirometry and now the DLCO.

I am perplexed as to why they are wanting this test? And two how will it be interpreted if I have both Asthma and COPD and one increases the DLCO and the other decreases? I am confused.  And should a blood sample be done for hemoglobin purposes, thus giving the DLCO a true and complete reading.

Response:  There is an overlap between asthma, chronic bronchitis and emphysema.  Even if you never smoked it is still possible to have COPD from chronic asthma.  “Airway remodeling” can occur because of asthma and when it does most of the asthma medications (bronchodilators) tend not to work very well any more.

The SSA website does have some explanation for what constitutes a disability based on spirometry and other pulmonary function tests.  For spirometry they state:

“During testing, if your FEV1 is less than 70 percent of your predicted normal value, we require repeat spirometry after inhalation of a bronchodilator to evaluate your respiratory disorder…”

But in Table I where they show the criteria used to evaluate the FEV1 there is nothing that specifically states they use the the pre- or post-bronchodilator results.

Their webpage does mention that the SSA may require a DLCO and Table III on the webpage indicates the criteria they use to evaluate results.  In your case they may be requiring the DLCO because of your diagnosis of COPD.

Interestingly, in the SSA explanation of DLCO testing they specifically state:

“We use the average of two of your unadjusted (that is, uncorrected for hemoglobin concentration) DLCO measurements reported in mL CO (STPD)/min/mmHg to evaluate your respiratory disorder under 3.02C1.”

I am not sure why this is the case since DLCO can be reduced because of anemia, but it’s what’s in their regulations.

I have been followed by a neurologist for a few years for suspicion of MS.

Just saw a respirologist- I assumed asthma would be the issue. The respirologist examined me (and the PFTs) and said I have respiratory muscle weakness and should pursue Bpap. Asthma is not the problem. I am scheduled for chest/sniff fluoroscopy.  My question is: why would there be an obstructive pattern with muscle weakness?

Response:  Airway obstruction is not the normal consequence of respiratory muscles weakness.

Respiratory muscle weakness primarily reduces the ability to completely fill and empty the lung.  During exhalation the elastic recoil of the lung (think of the lung being like a toy balloon) is responsible for a good part of how fast the air comes out of the lung. This means that as long as you can inhale you don’t need a lot of muscle strength to exhale. 

The presence of airway obstruction is usually indicated by a decrease in the FEV1/FVC ratio.  When respiratory muscles are weak both the FEV1 and the FVC decrease but usually at the same rate.  This means that the FEV1/FVC ratio usually remains the same even when there is significant respiratory muscle weakness – unless it was already reduced to begin with.

Hi, I am having difficulty taking full breaths in neck deep water and while laying flat.

I did have full PFT with spirometry. The test quality was reported as poor but an underlying obstructive defect of moderate severity was identified. The MEP(38% predicted) was markedly lower than MIP(46% predicted). I have been referred to a pulmonologist who suspects asthma. The question I have is: Does asthma present with low MIP/MEPs?

Response:  No, asthma is definitely not associated with the respiratory muscle weakness that your low MIP and MEP suggests.  Yes, it would be associated with the moderately severe obstruction you mentioned but to be definitive that it’s asthma and not something else you should have pre- and post-bronchodilator spirometry, a methacholine challenge or even just a trial period on the standard asthma medications.  

Your shortness of breath in the water and while laying flat (orthopnea) could be due to respiratory muscle weakness.  Upright and supine spirometry could help determine if it is primarily your diaphragm or your respiratory muscles in general that are weak (see Supine Spirometry for a more technical an in-depth discussion of this subject).  You might also want to consider seeing a neurologist.

I just took the PFT yesterday and my doctors app is not for a month.

Could you tell me if there is anything serious from these test results.  [results were placed in a table and edited for clarity]

Test: Predicted: Pre-BD Observed: %Predicted: Post-BD: %Predicted: %Change:
FVC(L): 3.57 2.08 58% 2.46 69% +19%
FEV1(L) 2.85 1.59 56% 1.80 63% +13%
FEV1/FVC: 80 77 96% 73 91% -9%
FEF25-75: 2.94 1.31 45% 1.20 41% -9%
FEF25%: 6.97 3.98 57% 6.36 91% +60%
FEF50%: 3.68 1.94 53% 1.72 47% -12%
FEF75%: 1.28 0.48 37 0.41 32 -13%
PEF (L/sec): 7.64 5.37 70% 7.40 97% +38%
FIVC (L): 3.57 2.08 58% 2.38 67% +14%
MVV (L/min): 123 57 46%
TLC (L): 5.76 8.45 147% 4.88 85% -42%
VC(L): 3.57 2.22 62% 2.50 70% +13%
IC (L): 2.72 2.18 80% 2.38 87% +9%
FRC (L): 2.38 6.27 263% 2.50 105% -60%
ERV (L): 0.11 0.12 18%
RV(L): 2.20 6.23 283% 2.37 108% -62%
RV/TLC: 39 74 191% 49 126% -34%
DLCO: 28.0 21.6 77%
DLCO/VA: 3.70 5.18 140%
VA: 4.18
RAW: 216 12.14 561% 585 270% -52%
GAW: 0.571 00.82 14% 0.171 30% +108%
sRAW: 5.15 79.04 1535% 16.02 311% -80%
sGAW: 0.194 0.013 7% 0.062 32% +393%
MIP (cm H2O) 108 113 105%
MEP (cm H2O): 202 90 45%

Response:  To start with I am going to ignore your pre-BD TLC, FRC and RV because I think they were seriously overestimated due to problems with your testing (see What’s the frequency, plethysmograph for a technical and in-depth explanation of the probable cause).  Your post-BD TLC, FRC and RV look much more realistic.

I am also going to ignore your airway resistance measurements (RAW, GAW, sRAW, sGAW) partly because the test quality looks very poor but also because these measurements aren’t usually very helpful in general.

In my lab this would be interpreted as “Moderately severe airway obstruction with a mild gas exchange defect and normal lung volumes.  The significant increase in FVC and FEV1 following inhaled bronchodilator indicates an element of airway hyperreactivity.  Respiratory muscle strength is within normal limits.”  

This could be consistent with COPD but fits several other lung disorders as well.

FYI, although your MEP is only 45% of predicted, the predicted value is too high and values above 70 cm H2O are within normal limits.  I also see some math errors in the DLCO/VA but that doesn’t change how the DLCO would be interpreted. 

When you look at spirometry to determine whether an obstruction is present…

do you look at the largest FVC and FEV1 regardless of whether they come from the same trial and if so can you give me authority for same.

Response:  The answer is a qualified yes, in that we always take the largest FVC regardless of which effort it comes from. Although the ATS/ERS statement on spirometry (the authority for this) also says that you should take the largest FEV1, again regardless of which effort it come from, my lab, and many others, also take the Peak Expiratory Flow into consideration as a quality indictor.  For a more detailed and technical discussion of this problem see  “Selecting the best FEV1. What role should PEF play?

The ATS/ERS statement on spirometry is considered the primary standard for performing spirometry throughout the world.  This was published in the  European Respiratory Journal in 2005 (volume 26(2): pages 319-338) and specific to your question refer to page 326, left column, the paragraph entitled “Test result selection”.  This article can be downloaded from the ATS website.

Are these results okay?

[Note: edited slightly for clarity]

Observed: Predicted: %Predicted:
FVC(L): 1.84 2.00 91.83
FEV1(L): 1.47 1.52 90.96
FEV1/FVC: 79.82
TLCO: 2.14 6.23 34.36

Response:  The spirometry results (FVC, FEV1 and FEV1/FVC ratio) are normal but your gas exchange (TLCO) is only about one-third what it should be.  Given that the spirometry results are normal there is no easy explanation for the decrease in TLCO.  More testing (lung volumes and a ventilation-perfusion scan for example) would be needed to determine the reason.

Note: In Europe and other parts of the world, DLCO is known as the transfer factor and not as diffusing capacity. For this reason it is abbreviated TLCO and not DLCO. There are also different units used for TLCO (mmol/min/kPa) and a multiplication factor of approximately 6 converts these units to those used with DLCO (ml/min/mmHg).

How would you interpret these results?

FEV1 57%, predicted FVC 70%, predicted FEV1/FVC ratio 73%, predicted, PEFR 66% predicted. I’m a 19 year old female non-smoker diagnosed currently with asthma but finding its getting worse (more coughing and wheezing at night, morning and on exertion) despite using a combination inhaler. Salbutamol helps relieve my symptoms but I’m worried more could be going on.

Response: Based on your FEV1 your results would be classified as moderately severe airway obstruction which I suspect is something you’d rather not hear.  Your symptoms and spirometry results are consistent with asthma, but other than that it’s all those results can say.  Your FVC is also reduced but that’s relatively common with the degree of airway obstruction you have. In order to rule in or rule out anything else you’d need to also have lung volume measurements and a diffusing capacity test. Since you are concerned I’d suggest that you ask your physician to order a more complete set of tests. 

Does FEV1/FVC has its upper limit value?

I don’t know why some people they have this value larger than 1? Is that reasonable? Thank you

Response:  The FEV1/FVC ratio can never be larger than 1.0. The FEV1 is the amount of air you can blow out in 1 second. The FVC is the maximum amount of air you can blow out. The FEV1 can never be larger than the FVC.  If you stopped blowing out after exactly 1 second then the ratio would be 1.0, otherwise if you continue to blow out then the ratio would have to be less than 1.0.  

The FEV1/FVC ratio decreases with age and at around age 20 it’s about 0.85 and around age 75 it’s about 0.70.

If you’re referring to percent of predicted however, then that’s a different thing.  It’s possible to have a higher FEV1 percent of predicted than the FVC percent of predicted and if that happens then the FEV1 % predicted/FVC % predicted ratio would be above 1.0.

I have been told I have mild restriction on my lungs due to systemic sclerosis.

At a recent PFT, these results were shared with me: FEV 70%, FVC 71%, and a DLCO of 54%. My rheumatologist told me this DLCO does not warrant treatment at this time, as it indicates a minor restriction. I have been experiencing increased shortness of breath of late. How low does a DLCO need to be before it is considered more serious?

Response:  DLCO is not a lung volume measurement and its results cannot be used to determine the amount or degree of restriction.  Your FVC is mildly reduced but because the FVC %predicted is often greater than the TLC %predicted, FVC cannot be used to either diagnose or assess the severity of restriction. Even though the severity of lung restriction is usually based on TLC however, your DLCO is moderately reduced and this at least suggests that your restriction is also moderate.

In my opinion a DLCO that’s 54% of predicted is serious (but please remember I’m a technologist, not a physician) and I say that because individuals with that low of a DLCO often require supplemental O2.  

Your rheumatologist may be using the FVC/DLCO ratio to assess  the severity of your systemic sclerosis.  Your ratio is 1.31 and the upper limit of normal for the ratio is usually considered to be 1.40 or higher.  This ratio is terribly flawed however, since it is based on numerous misconceptions and can be very misleading. 

Since your shortness of breath has become a concern for you I would suggest you get a more complete set of pulmonary function tests (with lung volume measurements and walking oximetry) and get a second opinion from a pulmonologist.

I’ve been diagnosed with asthma for years. I end up with bronchitis almost every year.

Usually multiple times or for a couple weeks to months at a time. This year I got sick again and was diagnosed with bronchitis over a week ago X-ray showed no pneumonia. Had a really hard time breathing 2 days ago and ended up in the ED. They put me on antibiotics and 60mg of prednisone. I woke up feeling the best I have in over a week today and had a scheduled PFT. Was a little short of breath when I got there and ended getting pretty light headed during the test but looking at the readings everything seems to be in the normal range. How come I feel like I have a hard time breathing out but the PFT says my FVC and FEV are normal. I was always told it was my asthma that made it feel like it was hard to get the air out of my lungs when I have my flare ups. Breathing in doesn’t seem to be an issue ( other then a pain when I take a really deep breath). It just feels like I almost have to push harder to breath it out. Like I’m using my stomach muscles to exhale. Could the prednisone affect the results. I do feel better then I did 2 days ago but not back to normal yet. Just really confused on why my PFT looked so good but I feel so bad.

Response:  Without seeing your current and past spirometry test results there is no easy answer and even then there may not be one with them.  But let’s talk about the concept of normal and what pulmonary doctors mean when they say that.

{Sorry, this is somewhat long winded but it’s important for everyone to understand some of the fine points.}

The issue of where the dividing line between normal and abnormal test results has been debated for decades among pulmonary physicians and continues to be debated. Everybody pretty much agrees about those people who clearly have normal lung function and those who clearly have abnormal lung function but there is a big gray area in between these two extremes where it isn’t clear at all.

First, normal values come from population studies where some number of people (dozens, hundreds or thousands) have been tested and their results have been statistically analyzed. Since they are supposed to be studying “normal” subjects that may be determined by their medical history, their current condition or just whether they were able to perform the tests correctly. So a good first question is how many people were in the study and who was included and who was excluded. A good second question is how well the different heights, ages, genders and ethnicities were represented. A good third question was how was it decided which test results were kept and analyzed and which results were rejected. What this means is that there are no perfect population studies; they’re expensive, time consuming and all of them have at least some limitations. Moreover, there can be some pretty significant differences between them and most importantly this means that there is no single, clear standard for what’s normal.

It also means that there are dozens of studies and reference equations. Somehow every PFT lab has to choose a set of reference equations that they think matches their patient population the best and there are few guidelines about how to do this. Some labs (like mine) choose a set of equations that comes from one of the largest and most statistically sophisticated population studies ever performed (NHANESIII) even though there is no assurance that the population that was studied is an exact match for their patients. Other labs choose based on the ethnicity or locality of the study population.  And yet other labs continue to use reference equations that may be out of date but keep them for continuity and because their physicians are used to them. This is why you can have tests performed at different PFT labs with essentially the same results but have different percent predicted values.

Once a set of reference equations has been selected there are two approaches to determining what’s normal and what’s abnormal.  First and simplest, everything that’s 80% of predicted and above is normal, everything that’s 79% of predicted and below is abnormal. This approach was developed somewhere around 1970 and remains in use today despite being relatively arbitrary partly because it’s simple and partly because it works reasonably well.  The second approach is the Lower Limit of Normal (LLN) and is statistically based. Basically, it says that the lowest 5% of the study population is probably abnormal and finds that dividing line with statistics. Neither approach is perfect and both draw a pretty broad line around what’s normal.

Finally what this means is that if your your lung function was above normal to begin with (remember, lung function a bell-shaped curve, so half of everybody should be above “normal”) it could have decreased noticeably but still be within normal limits. So as far as your pulmonary doctors are concerned your results may be normal but that doesn’t mean they haven’t changed enough that you can feel the difference.

Been short of breath.

Just got over the Flu which was believed to turn into bronchitis and was the cause of my breathing problem.  Had a PFT today and was wondering what the results mean. I believe they are saying I’m pretty normal.

                  Pre.   Post
FVC-          122%  125%
FEV-          115%. 121%
FEV/FVC.    95%.  98%

ERV.          178%
TLC           112%
RV-            80%
RV/TLC.      72%

DLCO        98%
DLCO/VA.   83%

Won’t hear from my doctor about it for a week so was hoping for a little insight before then. Thanks

Response:  Yes, all of your results are within normal limits.  The ERV is a little high, but that may be an artifact of how your slow vital capacity (SVC) was measured and isn’t anything to be concerned about.

I am scheduled for a complete pft with hemoglobin. What is that and what should I expect?

Response: Hemoglobin is the molecule that carries oxygen in your blood stream and what makes your red blood cells red. Your diffusing capacity (DLCO) test results are affected by the amount of hemoglobin in your blood (underestimated if hemoglobin is low, overestimated if hemoglobin is elevated).  DLCO tests should be routinely corrected for your hemoglobin but how this is done differs from lab to lab.  Some labs will measure your hemoglobin with a finger-prick blood test and that is most likely what you should expect.  

[Note: For a technical and in-depth discussion of hemoglobin and DLCO see Adjusting DLCO for hemoglobin.]

Other than that, complete PFTs usually consist of spirometry (possibly with and without bronchodilators), static lung volumes and a diffusing capacity (DLCO) test.

Is this normal?

Note: This was edited slightly for clarity

FVC(L) – 106%, FEV1(L) – 104%,  FEVI1/FVC-98%,  FEF25-75%(L/S)-81%, PEF-(L/S)-109%, FET(S)- – FIVC(L) – 105%, PIF(L/S) – – YOUR FEVI/PREDICTED – 104% IS ABOVE NORMAL

Response:  Yes, all the results are normal.

How would a history of pulmonary contusion, and severe chest wall injury change the accuracy of a PFT when measuring the progression of emphysema?

This event was five years ago, but there is still an inability to inhale deeply, and cough because of injury to the rib cage. There was also traumatic fracture of the scapula. This involved 10 fractured ribs, some in multiple areas.

Response:  Without access to chest x-rays and similar information this will have to be speculation but when the lung expands during an inhalation this occurs because the diaphragm moves downwards and the ribs move outwards. The ribs, of course, do not bend but they are curved and they rotate. This rotation has been likened to movement of a bucket handle and is what allows the chest to expand. A severe injury to the ribs can leave the ribs unable to rotate and this would mean that the only possible expansion of the lung would be through the movement of the diaphragm. This would limit lung capacity and although mechanical in nature would, by definition, be a restrictive disorder (i.e. a reduction in lung capacity). Emphysema is an obstructive disorder which is usually shown by a decrease in expiratory flow rates. There is no reason that an individual can’t have both a reduction in lung capacity and a reduction in expiratory flow rates and a small number of patients seen in my lab have a combined disorder like this.  A common feature in more advanced cases of emphysema however, is gas trapping (elevated RV and RV/TLC ratio) and hyperinflation (elevated TLC). If lung capacity is reduced because the chest cannot expand, then gas trapping can still occur but hyperinflation probably cannot. In addition, any gas trapping will cause a reduction in the FVC and therefore an increase in the FEV1/FVC ratio which could be taken as an indication that airway obstruction isn’t as severe as it really is.

Are these normal?

45 year old female, shortness of breath, cough, non-smoker. Are these normal, had a PFT and DLCO. FEV1 3.93 110% FVC 4.74 106% FEV1/FVC ratio at 83 Diffusion capacity at 35.50 107%

Response: Yes, all of the results are normal.

Is this normal?

fvc pre meas 3.38 ref 3.44 98%
fev1 pre meas 2.61 ref 2.83 92%
fev1/fvc% pre meas 77 ref 83 93%

Response:  Mostly yes but there is some disagreement about where to draw the line for the FEV1/FVC ratio.  The ATS/ERS recommends the use of the LLN (lower limit of normal) for the FEV1/FVC ratio which for most individuals is about 89-90% of predicted.  Some labs however, think this sets the bar too low and use an FEV1/FVC ratio <95% of predicted instead and there your results would be read as mild airway obstruction.

My personal opinion is that in general the LLN tends to under-diagnose airway obstruction and that <95% tends to over-diagnose it, and that to some extent it depends on the individual in question.  For a young individual in otherwise good health I’d say an FEV1/FVC ratio with a percent predicted of 93% is probably an indication of some airway obstruction.  For somebody that was elderly I’d be more inclined to believe that it was within normal limits.

I have been dx with mild restrictive ILD.

My FVC remains at 73, my FEV1 is 80, my FEV1/FVC 107. My TLC has been 83 in past and this time is up to 90. (All % of predicted). Does the increase of TLC indicate anything? My DLC unc remains unchanged at 85.

Response:  Strictly speaking your increase in TLC is not significant, at least by my lab’s standards.  You had an increase of about 8% and we’d want to see an increase of 10% for it to be significant.  

TLC is more difficult to measure than you might expect and we see a certain amount of variability from one test to another.  Within a single testing session this variability is usually less than 5%. When there’s a change from one visit to another it’s hard to say whether the change is because of testing variability or not, and that’s because these tests are usually only repeated on individuals where we are expecting to see changes due to a progression or an improvement in their underlying lung disorder.

What I want to know is do air trapping and/or hyperinflation cause TLC to rise?

All of my numbers as well as my flow volume loop indicate restrictive lung disease, except that the narrow, steep flow volume loop has a “scooped out appearance at the 50% location. The report says I have a combination of obstructive and restrictive lung disease. The problems is that the TLC is normal. But the RV is elevated and the RV/TLC ratio is increased, indicating air trapping. Does air trapping and/or hyperinflation cause TLC to rise?

Response: If your TLC is normal then by definition you do not have restrictive lung disease.  Restrictive flow-volume loops are usually are tall and narrow, but a reasonable number of people (5%?) have an elevated peak flow (the loop is significantly taller than expected) with a normal exhaled volume, often with “scooping” or “coving”, and with a normal FVC and FEV1.  By all criteria these results are normal.  This kind of loop may look “restrictive” in a general sense but all it means is that you can blast your air out faster than expected.

There is no “official” definition of air trapping.  My personal opinion is that you can’t definitively say there is air trapping until both the FRC and RV are elevated and that you can’t definitively say that hyperinflation is present until the TLC, FRC and RV are elevated.  An elevated RV and RV/TLC ratio often means that the vital capacity you performed as part of the lung volume test was underestimated and nothing more.

The answer to your initial question is that eventually, yes, air trapping and hyperinflation can cause TLC to rise but this takes quite a few years of chronic airway obstruction to occur and is less common than it used to be due to better treatment of COPD.  When COPD (emphysema and chronic bronchitis) progresses, the first change to lung volumes is an elevated RV, second is an elevated RV and FRC, and finally an elevated RV, FRC and TLC.

Finally, although it is relatively uncommon it is possible to have both restrictive and obstructive lung diseases at the same time.  However, for this to diagnosed you must have a TLC that is below normal and and an FEV1/FVC ratio that is also below normal.  When this happens RV (and the RV/TLC ratio) may be elevated but this does not happen in all cases.

What do these PFT results mean?

FVC 75% of reference; FEV1 – 73%; FEV1/FVC ratio 97% (No significant response to Albuterol). Total lung capacity normal at 97%; RV increased @127% of reference; RV/TLC ratio is increased @128% of reference (Air trapping suggested); ERV is only 29% of reference (what are implications of this?). DLCO is 56% of reference; DL-adj is also 56% of reference; DLCO/VA is 79% of reference. Please give me some answers based on the data given. I am kind of afraid I might have ILD.

Response:  As you are probably aware there are some inconsistancies in your PFT results.  If you took just the spirometry (FVC, FEV1, FEV1/FVC ratio) and the DLCO results by themselves, then I am sorry to say they would be consistent with a diagnosis of ILD.  The problem is that Total Lung Capacity of 97% of predicted doesn’t really agree with this.

At this point the only way to be sure would be to take a close look at each test’s quality.  For example, if the FVC was significantly underestimated for some reason this would mean that the FEV1/FVC ratio should really be reduced and then the overall picture looks more like COPD.  If the TLC is significantly overestimated and is really smaller than 97% of predicted then the picture is more like ILD.

Is this a good result considering I am asthmatic?

My parameters from august are: FVC 104% FEV1 106% FEV1/FVC 102% PEF 136% 

Response:  Yes, your results are normal with no sign of airway obstruction. 

How do you interpret this?

Fvc 107%
Fev1 96%
No change after albuteral

Tlc was 178%
RV was 295 %

The comment listed was Evidence of air trapping However
The dlco was actually elevated
Clinical correlation would be necessary

I have bad upper airway breathing when i lay down?


Your spirometry results (FVC, FEV1) likely shows some mild airway obstruction. 

The TLC and RV results (Total Lung Capacity and Residual Volume) do not make any sense and have to be due to a testing error of some kind.  An elevated TLC and RV can be due to air trapping but (1) only in the presence of very severe airway obstruction which you do not have and (2) in over 40 years of pulmonary function testing I’ve never seen a TLC that high that wasn’t the result of an error.

Mild airway obstruction with an elevated DLCO on the other hand, is often seen with Asthma and I would think this is far more likely than COPD or Emphysema.

The official name for having trouble with your breathing when you lie down is called Orthopnea.  If this only happens when you are sleeping or trying to sleep then it is probably a sign of Obstructive Sleep Apnea (OSA).  If it happens every time you lie down then it is more often a sign of problems with your heart.

I don’t understand how to read this?

My FVC was 5.34 predicted 107%
FEV1 was 4.36 predicted 112%
PEF25-75 4.53 predicted 127%
What does this mean is the test normal? There are other numbers that i don’t understand!!

Response:  Yes, these results are normal.  What are the other numbers?

Please explain the interpretation of these findings:

No change in FVC or FEV1. Clinical benefit may be seen in the absence of a response to bronchodilators in the laboratory. Increased TLC is suggestive of hyperinflation. Increased RV is suggestive of gas trapping. Diffusing capacity for carbon monoxide is moderately reduced.

(Note: results were edited slightly for clarity.)

Pre: Ref: %Ref: Post: %Ref: %Chg:
FVC (L) 3.28 3.33 99% 2.86 86% -13%
FEV1(L) 2.67 2.57 104% 2.37 92% -11%
FEV1/FVC 81 78 83
  Pre: Ref: %Ref:
TLC (L) 7.28 5.08 143%
RV (L) 3.99 2.00 200%
RV/TLC 55 30  
Pre: Ref: %Ref:
DLCO (ml/min/mmHg) 12.4 21.6 58

Response:  These results are contradictory and for this reason a bit of a puzzle. The Pre: spirometry results (i.e., FVC, FEV1 and FEV1/FVC ratio) are normal. Although at first glance the elevated TLC and RV results are consistent with the stated interpretation of hyperinflation and gas trapping this is not consistent with the normal spirometry. In fact this amount of hyperinflation and gas trapping would usually only be seen with very severe airway obstruction (FEV1 < 35% of predicted!).  Given this discrepancy I would be concerned about the lung volume test quality.  FYI, regardless of how lung volumes are measured (plethysmography, helium dilution or nitrogen washout) the majority of possible testing errors leads to the overestimation of TLC and RV and I have to suspect that is what we are seeing here.

The decrease in FVC and FEV1 following bronchodilator could be due to a sensitivity to the bronchodilator (a small number of individuals have airways that constrict rather than dilate after breathing an inhaled bronchodilator) and the reduced DLCO could be due to a real gas exchange defect but given the apparent problems with the lung volume measurements I would again be concerned about test quality.

Testing errors can lead to over- and under-estimation of all test results so in order to accurately interpret pulmonary function test results you also need to be able to assess test quality.  Unfortunately although the results presented here raise questions about test quality they do not provide anything that would allow it to be judged.

Concerned and puzzled about low FVC, low DLCO, but high DLCO/VA

FVC 60%, TLC 62%, DLCO 68%, VA 52%, DLCO/VA 131%
How do you interpret these numbers (consistent with two previous PFTs done within the last 16 months)? No symptoms, no SOB on activity, lung sounds clear, CT with contrast clear?? Thanks.

Response:  At first glance it looks like a mild to moderate restrictive disorder.  The elevated DL/VA suggests that this would be due to something other than interstitial disease and to some extent this would agree with the clear lung sounds and clear CT. FYI, many people do not complain of SOB until the DLCO gets closer to or below 60%.  As a cause I’d be looking for a reason why your lungs aren’t able to expand as much as they should and that would be at things like your rib cage, pleura and diaphragm.

At the risk of over-analyzing the results however, there is one problem with this is and that is that the VA is a fair amount less than the TLC (52% vs 62%) and this may be causing the DL/VA to be overestimated. There are generally two reasons why the VA can be lower than the TLC: first, that you didn’t inhale as much as you should have at the beginning of the DLCO test; second, that you also have some airway obstruction (reduced FEV1/FVC ratio). I would want to have a more complete look at your test results before I felt comfortable ruling out an interstitial component.

Note: The use of DL/VA when interpreting DLCO results is complicated and often misunderstood. If you want an in-depth look at this subject see Using DL/VA (no, no, no, it’s really KCO!) to assess PFT results.

Oximeter readings and Carbon Monoxide:


Response:    Finger (pulse) oximeters tend to overestimate the oxygen levels in your blood when carbon monoxide is present.  A laboratory instrument called a CO-Oximeter uses 8 wavelengths of infrared light and can measure both oxygen saturation and how much carbon monoxide is in your blood.  A finger (pulse) oximeter uses only 3 wavelengths and cannot measure how much carbon monoxide is in your blood and since the wavelengths for oxygen and carbon monoxide overlap, it will overestimate oxygen levels.  This is (or at least it should be) a well known problem in Emergency Rooms when they try to deal with people with carbon monoxide poisoning.

Without actually taking a blood sample and running it through a CO-Oximeter it is not really possible to predict how much carbon monoxide is in the blood of a smoker.  Levels of between 5%-10% are not uncommon and I’ve seen levels as high as 15%.  Every percent of CO in your blood is one less percent of oxygen that you can have.  For example, if you had a CO level of 10% (not saying you do) then the absolute highest that oxygen that can ever be in your blood (even if you’re on oxygen) is 90%.  The normal oxygen level is usually over 95%.

Please also note that the accuracy of a finger (pulse) oximeter is also dependent on good blood flow to your fingers.  If your fingers are cold or you have any kind of peripheral vascular disease then it may not read accurately.  Warming your fingers usually helps improve the signal quality.

PFT results for 59 y/o female former smoker with emphysema diagnosis.  

“Would these results explain sob (particularly the DLCO)? Also curious why the FEF25-75 and PEF would go down following after bronchodilator. Any thoughts/input would be much appreciated.”

FVC Pre 3.25/96% predicted FVC Post 3.69/109% predicted (%change 14)
FEV1 Pre 2.4/93% predicted FEV1 Post 2.75/103% predicted (%change 11)
FEV1/FVC Ref-78 Pre 76 Post 75
FEF25-75% Pre 1.96 77% Post 1.85 72% (%change-6)
PEF Pre 9.19 Post 8.55 (%change-7)
FET100% Pre 4.31 Post 6.49 (%change 51)

VC 3.43 101%
TLC 5.13 95%
RV 1.70 82%
RV/TLC ref-39 pre-33
FRC PC 3.22 106%
ERV 1.40 125%
Vtg 2.40

DLCO 20.0 77%
DL Adj 17.6 67%
DLCO/VA 3.61 71%
DL/VA Adj 3.17 no % given

Response:  With emphysema you’d expect to see airway obstruction (a reduced FEV1 and FEV1/FVC ratio), signs of hyperinflation (elevated RV) and a reduced DLCO.

Because emphysema can be diagnosed via x-rays and when mild may not greatly affect PFT results I can’t say this isn’t emphysema but in this case, the baseline spirometry is normal (normal FVC, FEV1 and FEV1/FVC ratio) and there was a significant increase in FVC and a borderline significant increase in FEV1 following bronchodilator which is more consistent with hyperreactive airways (asthma) than with COPD.  In addition the lung volumes (TLC and RV) were normal without any sign of hyperinflation (elevated RV and RV/TLC ratio).

The DLCO results however, are reduced and do indicate a mild gas exchange defect. There is also an indication that polycythemia (an elevated hemoglobin level) is present. Polycythemia can occur because of chronic hypoxia (low blood levels of oxygen) but the gas exchange defect is only mild so there may well be another reason.

The change in peak flow is not significant and is actually within the range of normal test-to-test variation.  The FEF25-75 measurement is dependent on both the FVC volume and the expiratory time of the spirometry test, and for these (and many other) reasons is not considered to be a reliable indicator of airway obstruction.

Knowing nothing else about the patient other than these PFT results in my lab these would probably be interpreted as follows:

“Mild gas exchange defect with normal spirometry and lung volumes. The significant improvement following bronchodilator indicates the presence of hyperreactive airways.  The isolated decrease in DLCO suggests pulmonary vascular disease.”

The reduced DLCO and possible asthma may explain some of the patient’s shortness of breath, but if they were looking for more answers a CardioPulmonary Exercise Test (CPET) would be a reasonable place to start.

What does DLCO say about restrictive lung disease?

My son’s (15) PFT results are as follows:
FVC 73
FEV1 74
DLCO. 95
FRC. 78
TLC. 71

For the DLCO the comments are:
1. diff single brath (TLC FRC)
2. Hgb corrected DLCO

I understand this is the indication for a restrictive disease but don’t undrrstand whether IDL related or neuromuscular. Would the DLCO number (based on the comments) be an adjusted number for either TLC or VA or the raw, unadjusted number?

Response: The DLCO has been adjusted (corrected) for hemoglobin.  Hemoglobin is the molecule that carries oxygen in the bloodstream so DLCO results can be low if anemia is present.  Adjusting DLCO for hemoglobin shows what DLCO would be if there was no anemia.

In normal lungs DLCO decreases as lung volume decreases, but not at the same rate.  If DLCO remains normal when TLC decreases this is a sign that the lung tissue is likely normal but that something is preventing the lung from expanding as much as it should be capable of.  This in turn can be a sign of neuromuscular disease (weak respiratory muscles) or chest wall disease (rib cage or pleura).

If DLCO was lower than TLC (which it isn’t) this would definitely be a sign of an interstitial lung disease (pulmonary fibrosis, sarcoidosis or others).

‘Diff single breath’ refers to the specific type of diffusing capacity test but since the Single Breath DLCO is the primary way DLCO is measured worldwide this comment appears to be somewhat redundant. To be honest I am not sure what the ‘(TLC FRC)’ is referring to since those values usually come from a different test and including them in a comment about DLCO is not a standard approach.  It is possible that the lab where the tests were performed was using the DLCO test to also measure TLC (basically a quick lung volume measurement is made as part of the DLCO test and although this measurement is similar to TLC there are technical reasons why most labs do not report it as TLC).

Are these results normal?:

Here are my results of my pft test im 54 year old male 60 pack year smoker not taking any meds: fvc: 105%, fev1 98%, fev1/fvc 93%,fef 25-75% 75%, ic 106%,erv 77%, rv 174% tlc 122% rv/tlc 141%. Are these results normal?

Response: The FVC and FEV1 are normal.  Depending on who you talk to the FEV1/FVC ratio is either within normal limits or shows mild airway obstruction. FEF25-75 is not a useful measurement.  I am concerned about the quality of your lung volume measurements (TLC, RV, RV/TLC) because they look like what I’d see if there was a leak during the test. Taken at face value I’d say they suggest hyperinflation but you don’t have enough airway obstruction to take that seriously.

What does an FEV1 of 77% indicate?

Response: If the FVC is normal it likely indicates mild airway obstruction.


Is a FVC of 125% good?

Response: Yes, for FVC bigger is usually better.  Having said that, your percent predicted can be overestimated if your age, height, gender or ethnicity was entered incorrectly or if an inappropriate reference equation was used.

Why does DLCO drop when FVC stays the same?

Response: DLCO and FVC measure different things. The FVC is dependent on the overall volume of the lung while the DLCO is a measure of the lungs ability to exchange gases. An example would be a pulmonary emboli (a blood clot in the lungs) which will lower gas exchange because blood cannot flow through the entire lung.  A pulmonary emboli does not necessarily affect FVC but it will decrease DLCO.

How can the FEV1/FVC be normal but the FVC be severely reduced?

Response: Usually FEV1 and FVC both decrease with restrictive lung disease (such as pulmonary fibrosis or sarcoidosis).  This means the FEV1/FVC tends to remain normal (or can even increase if FEV1 doesn’t decrease as much as FVC). FEV1/FVC is used to assess airway obstruction (such as asthma or COPD) and is not terribly useful when diagnosing or monitoring restrictive disease.

How important is the FEF25-75?

Response: FEF25-75 is the average expiratory flow rate during the middle 50% of a forced exhalation. At one time a low FEF25-75 was thought to be an indication of what was termed “small airways disease”.  FEF25-75 can vary a lot from one spirometry effort to another and depends a lot on how long you exhale.  For this and other reasons most pulmonary physicians no longer use this value for diagnoses or when monitoring spirometry values over time.

What does an elevated FRC mean?  

I recently completed complex lung function tests, results stated; normal airflow function, no change post bronch, normal TLC (101%), normal transfer factor (DLCO 111%) and transfer co-efficient (DLCO/VA 115%). My results were:

• FVC 106%

• FEV1 113%

• FEV1/FVC 91 (predicted was 83)

My concern is that the FRC result is elevated – predicted was 2.82 and my result was 3.63 (129%). I’ve read that this often indicates hyperinflation? What does this result mean in the scheme of the testing? Should I be concerned?

Response: FRC (and RV) are often elevated in severe COPD (emphysema or chronic bronchitis) and this is a sign of hyperinflation.  However, your spirometry results are normal so this is unlikely to be the case.  FRC is the amount of air in your lungs at the end of a normal exhalation and its volume is dynamically determined by the balance of forces between your lung, rib cage and diaphragm.  An elevated – or reduced – FRC by itself doesn’t mean a lot.  Since your FVC, FEV1, TLC and DLCO are all normal your elevated FRC may be due to something as simple as breathing too fast during the test.

Concerned about a low FEF25-75%

My FVC 104% of predicted and my FEV1 was 90% of predicted but the FE25-75 was only 62%. And the diagnosis on the report states” possible early obstructive pulmonary impairment” I just so happen to be at the end of a chest cold and still spitting up. I have been diagnosed previously with asthma but after the ventolin my numbers didn’t move at all. Would the chest cold directly affect the absorbtion rate of the ventolin (waited five minutes after inhalation) The tester said it still needs to be reviewed by the physician but I can’t help but think that the test is flawed, as I seemed rushed and not properly coached.

Response: I suspect that you were given a computer interpretation because the language sounds similar to some of those that I am familiar with.  Computer interpretations are very simplistic and for this reason I certainly hope that your test results are reviewed and interpreted by a pulmonary physician.

At my PFT Lab an FEV1 of 90% of predicted in combination with an FVC of 104% of predicted would indicate mild airways obstruction.  I realize that both the FEV1 and the FVC are “normal” but their ratio (FEV1/FVC) is below normal.  My lab has not used the FEF25-75 as part of the interpretation for probably the  last 20 years.  This is because the statistically normal range of FEF25-75 is quite wide.  There are also issues with how it is calculated that make it a less than reliable measurement.

In Asthma airways can be narrowed both because of muscular tightening (bronchoconstriction) and inflammation. Albuterol only affects the muscles of the airway and does not relieve inflammation.  Simply because you didn’t respond to the albuterol does not mean you are not an asthmatic.

I am sorry you were rushed and did not feel you were coached properly. I’d like to say that never happens at my PFT Lab but the fact is that we are often working under time constraints and have to do the best we can in less time than we’d like.

Concerned about low TLC and breathlessness:

Rv 77% predicted
Erv 70%  predicted
Frc 74% predicted
Tlc 89% predicted
Understand tlc is reduced due to low frc. Other values 100% predicted.
Also low fef25/75 . 71% predicted.
Why is this.
Breathless symptoms.

Response: First, your TLC is not reduced because a TLC that is 89% of predicted is within normal limits.  Second, FRC can be reduced – or elevated – without affecting the TLC. FRC is a balance point of the various forces between the lung, rib cage and diaphragm and it will change dynamically due to breathing patterns or posture.  FRC is often reduced when people are overweight, but TLC is usually completely normal at the same time.

When my lab used to look at the FEF25-75 (which we haven’t done for over 15 years) we considered 70% and above to be normal, so that is also normal.

Realistically what I see are relatively normal spirometry and lung volume results. What I don’t see are any DLCO (Diffusing Capacity) results, which would tell me how good your lungs are at getting oxygen into your blood stream and carbon dioxide out.

I should also mention that you can have perfectly normal lung function and still feel short of breath.  When somebody complains of shortness of breath, pulmonary function tests are a good place to start when you are looking for a reason but there are a variety of conditions that can make you feel breathless without affecting your lungs.

Do you have a question?

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