Partially, however, this may be due to mathematical coupling.
This could be due to mathematical coupling, because the formula used to determine ITBVI includes aortic CI, and thus aortic SVI indirectly, as a variable [ 22].
The conclusion that we drew on DO2 and consumption is hampered by the fact that our method of calculation of these parameters may be biased due to mathematical coupling of the data.
However, this correlation weakened when changes in ITBVI were plotted against changes in pulmonary arterial SVI, which was in part probably due to mathematical coupling between ITBVI and aortic SVI.
Furthermore, it has been suggested this so-called 'pathologic supply dependency' may result from spurious up-sloping of the VO2/DO2 relationship due to mathematical coupling of measurement errors when using a pulmonary artery catheter (PAC), because in some studies simultaneous independent VO2 assessment revealed a plateau [ 5, 6, 32].
Thus, the relationship between low nPNA and poor outcome could be due to uremia, low Kt/V or due to reported mathematical coupling between nPNA and Kt/V.
Hence, while the changes in O2ER may be true, they may also be due to the mathematical coupling of a shared measurement error.
Moreover, fat mass is a component of body weight, when both fat mass and weight are considered in a regression model, it will give misleading results due to the problem of mathematical coupling [ 30, 31] which has been raised since the early 20th century [ 32].
So, mathematical coupling can be excluded.
Moreover, the relationship between V O2 and D O2 is subject to mathematical coupling of data.
