SNT Gatchaman
Senior Member
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- New Zealand
Don’t his findings run counter to the idea that long Covid patients have low venous O2?
Hmm, really interesting. LC patients won't typically be attempting peak exercise of course, but this finding that they are higher at rest does run counter to what I was suggesting.
The studied LC patients were —
We consecutively enrolled all patients who had recovered from COVID-19 and were referred to the Brigham and Women’s Hospital Dyspnea Clinic (Boston, MA) and the Yale New Haven Hospital Pulmonary Vascular Disease Clinic (New Haven, CT) between February and June 2021 for unexplained exercise intolerance.
So presumably between 12-16 months disease duration for those that got COVID first, with some in the study a bit less.
At rest: higher (normal) SvO2
Exercise: very much higher SvO2
Normal controls can extract a lot more O2 during peak exercise. If LC patients can't, then the key factor in the equation during peak exercise might be the reduced diffusion capacity. Maybe RBCs can't offload oxygen due to the interposed clot between them and endothelium, but they are moving through relatively well during high output state. Alternatively, they have already formed micro-circulation AV collaterals and under high-demand states are bypassing much of the capillary bed.
If we find that low SvO2 occurs at the beginning, maybe it's only generally in the first 6-12 months, before micro-circulation changes bring it back to normal or high. This could vary depending on the number of patient crashes, placing additional stress on the micro-circulation.