I had a stress echo ran, PFT, all were normal. My pulse ox however wants to go into the mid 80's when I exert. I can run the vacumm and sweat will run off of me, and I can't breathe, a walk from the shower, the same. This all started a few monthes ago. I had to pressure the dr's to look for it, because they only looked at resting readings. They had thought pulmonary hypertension but ruled it out. Now I am scheduled for a CT of my chest. I have been in and out of ER alot in the past 5 years for Resp/infections. They have told me 2 times, they thought I had a blood clot in my lung but then when they look again it is gone. My father died from clots to both lungs. I have recently found out I have Factor 2 gene disorder. I am on warfarin the rest of my life. What things can cause a low pulse ox on exertion, but heart and lungs are healthy? My sleeping ox is fine, upper 90's?
What you have described suggests three or possibly four issues, some of which could be related: 1) recurrent lung infections and what predisposes you to them, (possibly evident on the CT Scan or due to an immunodeficiency state) 2) a genetic predisposition to abnormal clotting, deep vein thrombosis (DVT) and pulmonary emboli (PE) , 3) unexplained arterial blood oxygen saturation with exertion and, 4) the question of pulmonary hypertension.
Your description suggests that blood clots to the lungs (PE) have been suspected, but equivocally ruled-out. Reconsideration of the diagnosis of PE might be in order given the recurring question of pulmonary hypertension and, seemingly, a familial clotting disorder
You ask, “What things can cause a low pulse ox on exertion, but heart and lungs are healthy?” One not uncommon cause is what is called Right to Left Shunting (of blood). That is the passage of blood from the right side of the heart to the left side of the heart most likely through what is called a Patent Foramen Ovale (with a bypass of the lungs) or shunting that occurs within the lungs by way of what are called Arterio-venous (AV) malformations, that enable blood to pass through the lung and back to the heart without being oxygenated within the lungs. Shunting within the heart may not be evident on a Standard Echocardiogram. A-V malformations within the lungs are usually apparent on CT Scans of the lungs.
The presence of pulmonary hypertension (whatever the cause) can potentiate the shunting of blood within the heart.
Finally, if your oxygen saturations are consistently higher (even with each in the “normal” range) when supine than when seated or erect this could be the result of a condition called Orthodeoxia.
You might wish to discuss the preceding with your doctors to elicit their opinions on the likelihood of any of the above.
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