https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6157889/
https://pubmed.ncbi.nlm.nih.gov/30256820-hypocapnic-cerebral-hypoperfusion-a-biomarker-of-orthostatic-intolerance/?dopt=Abstract
Hypocapnic cerebral hypoperfusion: A biomarker of orthostatic intolerance