Change in cardiac output. The change in cardiac output (ΔCO) measured by intermittent thermodilution cardiac output (ICO) and by either arterial pressure-based cardiac output (APCO) or continuous cardiac output (CCO). ΔCO is the difference in two measurements (by one method) of cardiac output expressed as a percentage of the mean of those measurements. Points that fall within squares along the central diagonal (green squares) reflect equivalent changes for the test cardiac output measurement method (APCO or CCO) and ICO. Points that fall within the yellow squares reflect changes of similar direction but different magnitudes. Points that fall within white sections in the upper left and lower right reflect non-correlated changes between the test measurement method and ICO.