Tuesday, February 13, 2007

Low DLCO

Here is a submission from John B: It is interesting that it is close to the very first post of this blog.

I continually test a low (60% I think) DLCO on a PFT. All other parts of that test are normal.
I have dizziness, lightheadedness, sob (random- at rest or exertion). Palpitations at times, but not nearly as often as in the past.
Occasional feeling of pressure in chest. Echo was normal, but imo it looks like values have been increasing over the past 2 years- still in normal ranges, but I do show some trace/mild tricuspid regurg and trace mitral regurg.
Two times I have done a cardiopulmonary stress test, and both times it shows a cardiovascular limitation evidenced by crossing of the anaerobic threshold earlier than I should- metabolic acidosis after exertion.
Nuclear stress test shows no blockages.
Also, my own testing with a pulse oximeter seems to indicate occasional drops in my O2 to as low as 92, but then quickly recovering to 96-98. This has never happened in doctor's office with their oximeters, so I don't know if mine is accurate (however, when testing my wife as a control subject, she always shows 96-98).

high-res CT scan of chest - normal (6 months ago)
non-invasive ct angiography (body scan) - normal lungs / lung blood vessels (1+ year ago)
- calcium score was 0 (2 years ago)

multiple echocardiograms are in normal range but show trace / mild regurgitation
- cardiopulmonary stress test shows a cardiovascular limitation evidenced by a metabolic acidosis at peak exercise
- low DLCO (+-60% of predicted - 1 month ago)
- nuclear stress test shows no blockages (1.5 years ago)
- triglycerides 270 - vldl 56 - ldl 240 - hdl 36)
- lyme disease- treated with abx in past

No one knows what to make of this. I was thinking of requesting a stress echo, to see if there is more regurgitation after exercise.
Any other tests I should have done? Would really appreciate some assistance. I can provide more specific data if needed.

-John

11 comments - CLICK HERE to read & add your own!:

Anonymous said...

What is your BMI? DLCO/VA? Desaturation with ambulation? Estimated PAP on echo?
Isolated low DLCO and abnormal CV limitation on CPX suggest pulmonary HTN.
You might need rt heart cath.

Baleeiro said...

I think the R heart cath is a good idea. A stress echo may also uncover subtle changes like exercise-related LV diastolic dysfunction that may be missed on a plain echo.
The normal HRCT and lung mechanics make significant primary lung disease very unlikely.
The Mayo clinic has been doing more exercise heart caths and finding a lot of these exercise-related-only subtle cardiac findings.
Finally some component of anxiety/stress leading to primary hyperventilation may explain the random episodes of dyspnea at rest.

Johnny B said...

Cardiologist refused a rt heart cath years ago when the pulmonologist requested one (after seeing the echo). Cardio docs keep saying I am fine. Even the pulmonologist seems to have ruled out PH now, though I am not sure why, esp with low DLCO and not much else to go on.

BMI - unknown- I am 5'7" and 145 lbs- not overweight

DLCO/VA mL/mHg/min/L = 5.86 (from 2005 - haven't received new one yet)

Desaturation with ambulation- not usually- did see this once on a CPX awhile back (down to 93 on pulse ox but no ABGs done that time), but a more recent one showed no desaturation on exercise.

Desaturation seems to be either at rest or random- sp02 is sometimes slightly lower when sitting and will go back up when I stand / move.

I don't see anything specific to estimated PAP on the echo results. Any specific value I should be looking at?

Thanks.

Anonymous said...

I would suggest you go to Mayo to get an exercise heart cath done if local cardiologists are refusing to do so.

Jeff H said...

I agree that this sounds like pulmonary hypertension. It is not common for echocardiograms to underestimate RVSP's and PAP's, but the increasing tricuspid regurgitation you mention is also suspicious. An important question, however, is whether this is progressing. How many years has the DLCO been stable?

The gold standard here is a right heart cath with a vasodilator study. As Carlos brought up, subtle pulmonary hypertension may be exacerbated with exercise. So, I think that is a very reasonable next step, but you need to be seen at a center with expertise in pulmonary hypertension.

Finally, just to throw this one out there, and it does not explain the low DlCO, but a metabolic myopathy could also cause an early lactic acidosis, and can effect the heart causing a cardiovascular limitation on CPET.

Johnny B said...

DLCO has been around the same since 2003.... made mistake before on DLCO/VA. Here are old and new results:

2005: DLCO=22.3 DLCO/VA=3.53 VA=6.33

2007: DLCO=21.4 DLCO/VA=3.26 VA=6.58

But my FVC, FEV1, FEV3 are all like 120% of normal.

One doctor suggested "a leak in the system" in the past but never followed up with other tests.

So a rt heart cath may be in order? I'll bring a printout of this discussion and ask.

Jeff H said...

Good luck. But I'll caution you that we have only heard a small amount here. Only your physician, with all information and necessary studies, is in a position to assist you in medical decision making.

Anonymous said...

John, I am in similar boat as you but without as much cardiac testing. Had one stress echo - initially reported as normal but E/I ratio indicating possible early diastolic function. No numbers were given on report at all though. Just diagrams marked o.k. What the heck is one supposed to do with this kind of report, and from a major institution. Requested they at least assess for sign of PH, all I got back was the same report - the comments about diastolic dysfunction were taken out (which probably isn't uncommon in RA, or my family and now many women in general), and just replaced with, "RV - 19".

My dlco has been steadily dropping since 2001, dlco/VA has dropped also. 2001 was something like 15.0, then brief increase to 18, and every test since then dropping, to about 13.5 I think is where I am at now (48% of predicted, given weight gain over years - but about 60% if you don't factor the weight gain or age in). Believe dlco/va has dropped from 80% to 60%. BMI about 30. I do have RA, and previous GGO, now gone, but now do have subtle but obvious mosaic (more lower half of lungs)on Inspiratory CTs taken 2003 and 2005. Expiratory views not done. No one seems to be too concerned about this. Stress echo ordered by primary for some chest pain, not for dlco. Sats are fine, in fact better last couple of years than first few years. Spiro and volumes at 100% for most part. RV and ERV vary most. TLC improved with clearing of GGO. RV/TLC ratio normal. FRC a little low. Apparently some report in Chest this month about waist/hip ratio affecting gas exchange. Study done on morbidly obese undergoing bariatric surgery. Have seen previous study on same population associating low dlco to GERD.

mark a said...

I have to second, third or fourth all the above. I had a patient not to long ago with an isolated reduction in DLCO and a normal ECHO. Sent him for an exercise cath and it was pulm htn. Additionally, the reported error on ECHO in estimating PAP can be as high as 20mmHg.

Johnny B said...

Update: Due to some palps and occasional chest pains, along with the SOB that comes and goes, the cardiologist finally ordered a cath, and after talking to my pulmonologist, they did the rt-heart cath as well.
PAP was normal! Good news.
Still doesn't explain all the symptoms, though. So we seem to have ruled out pulmonary hypertension... I know a metabolic myopathy was suggested as well. I don't even know what type of doc to see about getting tested for that. Isn't it uncommon? Any ideas?

Thanks.

Kimberly said...

I just came across your post. I am a 20 year old female and experiencing the exact same problems except my o2 levels have stayed at 100% during testing. I have been experiencing SOB, unusually high amount of persperation with exercise, chest tightness and pain, pins and needles sensation down my left arm and bursts of pain only on my left side of my chest at times. This has been going on for over a year now. During the begining stages I had viral meningitis associated with lyme disease. I have had the echocardio stress test, pulmonary stress, CT scans with and without dye, PFTs....and am actually scheduled now to have the right heart catheterization done now. I have a low DLCO and my anerobic threshold is borderline.
I was recently told I have one heart beat louder than the other and it become more noticeable when I lay flat on my back. I was told I most likely have pulmonary hyperstension but wont know for sure until the catheterization tests.
Have you recently been diagnosed with anything else?