What could cause this?

[Hey Jude]

I have a low oxygen saturation rate that varies according to my activity level.  This was discovered when I had a routine CBC that showed my red blood count was high at 5.94 and my hematocrit was very high at 58.5.  The doctor thought I was going to have a stroke and sent me for a phlebotomy the next morning.  While in his office, he took my oxygen saturation rate and it was 87.  With that result, he also sent me for a chest xray and arranged for me to see a Hematologist.  I was put on oxygen 24/7.   My lung function tests suggest mild emphysima and asthma, but nothing that could account for the low oxygen saturation rate (off oxygen from 87-73 according to my O2 meter).  The Pulmonologist put me on Advair and Spiriva.  On a retest of lung function, my diffusion rate dropped even lower from 65 to 43.  Extensive Hemitology testing ruled out Polycythemia Vera.  I do not have any symptoms such as coughing, wheezing, feeling short of breath, feeling tired.  There is no swelling in my ankles.  My lung sounds have been completely clear every time.  Blood gasses show low O2 and low CO2.  I had a CT Angiogram with and without contrast, a VQ scan from head to toe, a Vent/Perf Lung Scan, a Bubble Echo Cardiogram, an abdominal ultrasound and several other chest xrays.  They show no shunts, no embolisms, no fibrosis.  A sleep study showed no apnea.  Several days ago, I had a Transesophageal Echo behind my heart to see if there is a hole behind a bulge in my heart.  This was inconclusive on the Bubble Echo Cardiogram.  The TEE did not detect a hole in my heart.  This has all been going on for 7 months.  I know that diagnosis is ultimately the hardest thing.  Do you have any suggestions of what could be causing my low oxygen saturation rate when I do not have any symptoms of anything?  Even when my saturation rate goes into the 70s, I still do not have any symptoms like shortness of breath, feeling tired, coughing, etc.  Thanks so much.  This is a great service to everyone.

[National Jewish Health]

Despite the alleged normality of your many tests, it is highly likely that you do have a shunt causing this marked fall in arterial oxygenation.  Intra-cardiac and intra-pulmonary shunts are usually, but not always, demonstrated by one or more of the studies you cite.  For that reason, you should probably have a cardio-catheterization to rule out shunting in lung or heart.

In addition, there is a condition called, hepatopulmonary syndrome.  It occurs in association with cirrhosis of the liver and large drops in oxygenation can be seen with this condition.  While highly unusual, arteriovenous shunting can sometimes occur in organs other than the heart, lungs and liver.  Abnormally low oxygen saturations can also be seen with abnormal hemoglobin, some do not carry oxygen well, including methemoglobinemia, which is an hereditary or acquired hemoglobin abnormality, following exposure to a variety of drugs/chemicals.  You should be tested for all of these by what is called hemoglobin electrophoresis.  Chronic carbon monoxide poisoning should also be considered.

Good luck

Please give us a follow-up to let us know how you are doing.

[Sunny602]

Hmm, the email didn't show up...I hope that you saved my email address, I will be looking for your email! Sunny :)

[Sunny602]

Hi maggie, I don't think I got them, but maybe they wound up in the junk mail and sometimes I get click happy and delete them without looking more closely. That has happened before with people who emailed me in the past. I am so sorry...you can always email me again. I hope that this shows up with this post... ***@****  
I look forward to your post....you are also right about the shunt, I remember the doctor saying what you did and I did do the 100% rebreathing O2 test. I too passed that one. I guess if you shunt, then the result would still be low oxygen levels on your blood gases. So yeah, that one is defintely a test to consider before more invasive tests are done if it hasn't already been done. Sunny :)

[maggiemag]

Sometimes a shunt doesn't show up with the usual tests.  I had a blood gas after breathing 100% oxygen for 15 min.  For me the test was within normal limits, but maybe they could try that.

Sunny, did you ever get my emails?  I also have a myopathy and low MIP's and MEP's.  It was a couple of months ago.  I have more questions for you. :-)

[Sunny602]

I was put on blood thinners to help with the blood clots. The diffusions got better in time. What complicates things with me is that my diaphragm was weakening too, so my PFT's were drifting downwards over time anyhow (diffusion would not be affected in that case, that's why the doc was puzzled when mine tanked). My oxygenation only improved slightly over time...it was short lived as my diaphragm got weaker (I have myopathy, a disease that essentially weakens your muscles..to this day the docs do not know why this has happened to me). It is something else that you don't have symptoms with that low oxygen level..I usually felt very out of sorts. I bet they have probably ruled out diaphragmatic weakness with you, your PFT's would show clues that would make a doc think a neuromuscular etiology was at hand. My inspiratory pressures and expiratory pressures were way below the norm which means that my effort wasn't great due to muscle issues. They also did a fluroscopy of my diaphragm, a special x ray that allows the doctor to visualize your diaphragm as you breathe. My results sucked..they barely moved! My pulmo actually demonstrated normal movement on himself, then replayed what they saw on me...it was pathetic. My muscle tests were abnormal too, so that explained my poor PFT's. When the diffusions went down (I think it was 40%), they scratched their heads as that doesn't happen with neuromuscular problems, usually causes would be advanced emphysema, fibrosis, blood clots, or other disorders that affect the exchange of oxygen to your blood. So, like I said, they put me through many many tests to figure out why this had happened until the biopsy, that really was the last test they could have done to me.
About the oxygen, I was on oxygen from the beginning of my diaphragmatic issues, but required more when the blood clots occured. It did get better for a short period of time until my weakness worsened. My diffusions did go back to normal though. Just not my PFT's...
So, as you can see, I too drove the doctor's absolutely nuts...don't you hate being called a medical conundrum? Or mystery for that matter? I felt like I was a green bug under a microscope when the docs did their rounds on me. I bet you feel the same...Again, I sure hope that they figure this out for you...Sunny

[Hey Jude]

Hi Sunny...I forgot to ask.  What did they do about the detected clots and did it get your oxygen diffusion level back to normal to get you off the oxygen?  Thanks a lot.  Hey Jude

[Hey Jude]

Thanks, Sunny.  The thing is that I am not short of breath at all with or without movement.  With or without oxygen, I am not dizzy, short of breath, and dont feel tired even when, off oxygen, my oxygen level goes into the 70s.  I will ask my Pulmonologist about what you said, but I do not have any of those symptoms.  What do you think?

[Sunny602]

Wow, you must be going out of your mind trying to find out the cause. I feel for you...I went through something similar 5 years back. I had low O2 levels and diffusion issues as well. Went through all of the tests you described above. I too was short of breath with any movment...my docs suspected pulmonary hypertension, that was ruled out with a right heart cath, fibrosis..ruled out with a CT scan, went throug the V/Q scans too. What they ultimately found was short of amazing...the doctors finally did what is called a VATS lung biopsy, they essentially go in with a scope through your chest to retrieve some lung tissue to look at and test. They found this...micro emboli in my arterioles!! That explained my low diffusions..I had little blood clots in my lungs. This was not detected by the V/Q scan or the CT scan, two commonly used tests to diagnose blood clots to the lungs. Needless to say, my pulmo was totally surprised (and so was I). Maybe the docs should consider a biopsy..I know it sounds drastic, but with all that you have been through perhaps it is one last test to really find out what is wrong. I am sure that there are other reasons why one's diffusions would be so low, I am just telling you one example that would do this. Either way, I hope that you find out what is causing this...I understand your frustrations. Sunny

[Hey Jude]

A few more details about me are that I am a 62 year old female, 5' 4" tall, weight 120 lbs., with a normal blood pressure in the 90s over the 60s.