Thursday, May 05, 2005

Isolated DLCO

I'll start it off with a patient referred to me for dyspnea with an isolated DLCO. Leave any comments about what you might do next or other suggestions/questions. Not all of the ones you all present have to be this long.

50-year-old woman with a history of arthritis (rheumatoid factor negative in 2001) who had bilateral hip replacement (right hip in December and left hip in February 2005). Last month, one month postop, the patient noticed that she was out of breath while walking from the parking space to the local store. No CP. Since that time, she has had dyspnea on exertion with just minimal exertion such as walking from room to room. She denies any dyspnea at rest or other triggers, although on that first episode described above the air was more cold. The patient denies any acute chest pain, cough, fevers, chills, night sweats, or other constitutional symptoms. The shortness of breath is relieved with rest. She went to a local Emergency Room for this dyspnea and the workup revealed a normal BNP, negative lower extremity Dopplers, an EKG with normal sinus rhythm and a VQ scan that was read as "normal appearing." A confirmatory PE-protocol CT was not done, perhaps because she had a history of getting nauseous from the dye. Other workup included a spirometry with evidence of abnormal DLCO. Of note also, the patient did have some postop anemia, but this has been treated with iron.
PAST MEDICAL HISTORY: Arthritis, depression.
MEDICATIONS: Effexor, Xanax, and iron.
SOCIAL : ex-smoker. She did smoke half a pack a day, quit in 1999. The smoking was intermittent. Occupation is a lawyer. No known occupational exposures.

FAMILY HISTORY: Father has emphysema (smoker)

Exam: VSS Weight 145 lb Lungs: CTA. Cor: normal. Ext no edema.

Labs: Hct 40.
ABG 7.47/28/113 on RA. carboxyhemoglobin not high.
Lactate was 7.1 but this must be an error.
PFTs: everything is normal (including RV, TLC, IVC). DLCO is 61% predicted. corrected to VA (if you beleive in that) makes it still low at 68% predicted.

HRCT: No evidence of ILD. radiologist called masaic pattern on expiratory LLL but the call is soft.
PE-protocal CT was negative for embolus.
Echo showed PAP of 25 with normal vnetrical and atrium size.

Exercise test was order and not done yet.

Here is the HRCT with the possible mosaic.


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

Carlos said...

Her A-a gradient is completely normal (actually pretty low). Her pH is a bit lowe than I would expect with just primary hypervent with PaCO2 down to 28. Do u think there is something more to that lactate? Like some metabolic/mitochondrial myopathy with fatigue/dyspnea and a met acidosis driving the hyperventilation?

Jennings said...
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Jennings said...

Yes I ALSO found it strange that her Aa was normal in the setting of an abnormal abnormal DLCO. Didn't think about various myopathys as possibilities. Stay tuned for results of exercise test (due this friday).

Jennings said...

Update: those gases I posted were from the peak exercise (same with the lactate). I will await the official exercise test results in terms of anerobic threshold etc. That should shed some more light on this...


Carlos said...

So she had a pretty good acidosis. Even for peak exercise 7.1 Lac seems a bit high.
Maybe her dead space is slightly elevated (we'll see the Vd/Vt) due to very early COPD, still with good mechanics (hence the low DLCO) and she has a myopathy (acidosis, fatigue, etc.)

Jennings said...

The exercise showed AT reached at only 26% of predicted and no dead space. This goes against any lung involvedment (and the HRCT supports that). That leaves myopathy and heart disease I think. It could be peripheral vasc disease, but she doesn't have any exertional pain in the muscles so prob. not. I would say it would be early heart, as I can't see how a myopathy would lead to decreased DLCO especially with lack of
CO2 retention on exercise. I think I will get a stress-echo.. Everyone agree?

Carlos said...

A stress echo is a good idea but I think I would still pursue the myopathy. The (posssible) myopathy would not be the cause of the decreased DLCO but she may have two processes.

Mike L said...

Have you checked a TSH in this patient. Also, this Fe deficient anemia... how bad is it? I believe that anemia alone can make the DLCO low and may give you a cardiac pattern on the exercise test.

Jennings said...

I didn't check a TSH. Does that give low DLCO? Also, a recheck of the anemia showed that it had resolved but the repeat DLCO was still low in the 60's.

Jeff H said...

I like the idea of a myopathy, but agree that it doesn't explain the DlCO. She had a normal BNP, but has she had a regular Echo yet? I don't think that PE has been ruled out (although a normal Aa speaks against it). I think an echo to look for evidence of pulmonary hypertension might also be useful. Could explain the fatigue, dyspnea, and decreased DLCO. Any associated low CO state could explain the early AT and rapid elevation in lactate.

Jennings said...

No the echo (resting) was normal with a PAP of 25. PE was ruled out with a dedicated pe-protocol CT, which I got after a V/Q was read as normal. Sop i think pe is ruled out. Also, to boot, dopplers of lower ext were negative on that ER visit she had.

Anonymous said...

Any final diagnosis on this patient?

Anonymous said...

Is it a clear case of COPD? As the DLCO states!!

Anonymous said...

Bubble study to evaluate for pulmonary AVM'S?