“…Finally,15O 2 is considered the gold standard for noninvasive estimation of MVȮ 2 because oxygen is the final electron acceptor in all pathways of aerobic metabolism. This approach yields absolute values of MVȮ 2 and is impervious to the confounding influence of pathological disease states. However, availability, logistics, and data analysis are challenging, making it unreliable and difficult to apply widely.…”