Tracking Changes in Cardiac Output

Abstract

When comparing 2 technologies for measuring hemodynamic parameters with regard to their ability to track changes, 2 graphical tools are omnipresent in the literature: the 4-quadrant plot and the polar plot recently proposed by Critchley et al. The polar plot is thought to be the more advanced statistical tool, but care should be taken when it comes to its interpretation. The polar plot excludes possibly important measurements from the data. The polar plot transforms the data nonlinearily, which may prevent it from being seen clearly. In this article, we compare the 4-quadrant and the polar plot in detail and thoroughly describe advantages and limitations of each. We also discuss pitfalls concerning the methods to prepare the researcher for the sound use of both methods. Finally, we briefly revisit the Bland-Altman plot for the use in this context.

Evaluation of cardiac output by 5 arterial pulse contour techniques using trend interchangeability method

“…[9,10] However, this method is associated with a high risk of misclassification when 2 methods of measurement indicate changes in opposite directions. [11] Moreover, this method does not take into account the repeatability of the RM and the polar limits of agreement are not calculated a priori, thereby preventing objective interpretation.…”

Comparison of the ability of esCCO and Volume View to measure trends in cardiac output in patients undergoing cardiac surgery

“…The advantage of this method is that it is easier to understand within the graph while the opposite variations of CO are also analyzed. However, determination of the angle is not straightforward and cannot be simply calculated as Saugel [19] has proposed.…”

“…Four-quadrant trend plots with central exclusion zone (10%) for assessing the ability of the esCCO and the VV to trend CO wherein the 45° line corresponds to the line of identity. The more the plot is far from this line, the higher the radial angle [19]. With ΔesCCO-CO values in the x axis and ΔVV-CO in the y axis, radial angle is positive when ΔesCCo-CO < ΔVV-CO, and radial angle is negative when DesCCO-CO < DVV-CO, whatever the direction of the mean ΔCO (increase or decrease).…”

“…Agreement of the change in CO (∆CO) between ΔesCCO-CO and ΔVV-CO DesCCO-CO and DVV-CO (∆CO: difference of the measurements between T1 and T2, between T3 and T4, and between T5 and T6) was assessed using the fourquadrant plot approach recently refined by Saugel [19]. Values presenting a ∆CO < 10% for both methods were excluded for the analysis (central exclusion zone) [20] This central exclusion corresponds to the noise of the device, due to the insufficient precision of the technique.…”

Innovative noninvasive hemodynamic monitoring: curb your enthusiasm after initial validation studies and evaluate the technologies’ clinical applicability

“…From the flood of data on the measurement performance of innovative less-and noninvasive hemodynamic monitoring technologies several critical problems arise: First, as discussed in detail previously [4][5][6], there are numerous unresolved problems regarding the design and interpretation of validation studies, including the interpretation of statistical methods [7,8] and the definition of poor, acceptable, and good agreement with established reference methods (such as pulmonary artery or transpulmonary thermodilution). However, even if we pretend that we theoretically know how to define ''clinical acceptable agreement'' in validation studies, a second major problem arises, namely: Can the results from positive validation studies be indiscriminately transferred to our daily clinical practice?…”