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

View Article: PubMed Central - PubMed

ABSTRACT

Cardiac output measurement with pulse contour analysis is a continuous, mini-invasive, operator-independent, widely used, and cost-effective technique, which could be helpful to assess changes in cardiac output. The 4-quadrant plot and the polar plot have been described to compare the changes between 2 measurements performed under different conditions, and the direction of change by using different methods of measurements. However, the 4-quadrant plot and the polar plot present a number of limitations, with a risk of misinterpretation in routine clinical practice. We describe a new trend interchangeability method designed to objectively define the interchangeability of each change of a variable. Using the repeatability of the reference method, we classified each change as either uninterpretable or interpretable and then as either noninterchangeable, in the gray zone or interchangeable. An interchangeability rate can then be calculated by the number of interchangeable changes divided by the total number of interpretable changes. In this observational study, we used this objective method to assess cardiac output changes with 5 arterial pulse contour techniques (Wesseling's method, LiDCO, PiCCO, Hemac method, and Modelflow) in comparison with bolus thermodilution technique as reference method in 24 cardiac surgery patients. A total of 172 cardiac output variations were available from the 199 data points: 88 (51%) were uninterpretable, according to the first step of the method. The second step of the method, based on the 84 (49%) interpretable variations, showed that only 18 (21%) to 30 (36%) variations were interchangeable regardless of the technique used. None of pulse contour cardiac output technique could be interchangeable with bolus thermodilution to assess changes in cardiac output using the trend interchangeability method in cardiac surgery patients. Future studies may consider using this method to assess interchangeability of changes between different methods of measurements.

No MeSH data available.


First step of the interchangeability method to assess changes in measurements between 2 methods of measurement. For a repeatability of 20% for this example, point A could change to either point B (interpretable variation) or point B’ (uninterpretable variation). The repeatability of measurement, indicated by the solid segment on both sides of each point, overlaps for points A and B’.
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Figure 1: First step of the interchangeability method to assess changes in measurements between 2 methods of measurement. For a repeatability of 20% for this example, point A could change to either point B (interpretable variation) or point B’ (uninterpretable variation). The repeatability of measurement, indicated by the solid segment on both sides of each point, overlaps for points A and B’.

Mentions: According to the guidelines for reporting reliability and agreement studies,[14] we propose a new method to assess the interchangeability of the trends observed with 2 methods of measurement. The first step of the proposed method is to determine whether or not each variation is interpretable. We postulate that a change can only be interpretable when the confidences intervals of the reference values (reference value ± reference value multiplied with the repeatability coefficient) of the 2 measurements, do not overlap. A change between points A and B would then be interpretable (A and B with nonoverlapping confidences intervals) or uninterpretable (A and B’ with overlapping confidences intervals), as described in Fig. 1 or Fig. 3A.


Evaluation of cardiac output by 5 arterial pulse contour techniques using trend interchangeability method
First step of the interchangeability method to assess changes in measurements between 2 methods of measurement. For a repeatability of 20% for this example, point A could change to either point B (interpretable variation) or point B’ (uninterpretable variation). The repeatability of measurement, indicated by the solid segment on both sides of each point, overlaps for points A and B’.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4998299&req=5

Figure 1: First step of the interchangeability method to assess changes in measurements between 2 methods of measurement. For a repeatability of 20% for this example, point A could change to either point B (interpretable variation) or point B’ (uninterpretable variation). The repeatability of measurement, indicated by the solid segment on both sides of each point, overlaps for points A and B’.
Mentions: According to the guidelines for reporting reliability and agreement studies,[14] we propose a new method to assess the interchangeability of the trends observed with 2 methods of measurement. The first step of the proposed method is to determine whether or not each variation is interpretable. We postulate that a change can only be interpretable when the confidences intervals of the reference values (reference value ± reference value multiplied with the repeatability coefficient) of the 2 measurements, do not overlap. A change between points A and B would then be interpretable (A and B with nonoverlapping confidences intervals) or uninterpretable (A and B’ with overlapping confidences intervals), as described in Fig. 1 or Fig. 3A.

View Article: PubMed Central - PubMed

ABSTRACT

Cardiac output measurement with pulse contour analysis is a continuous, mini-invasive, operator-independent, widely used, and cost-effective technique, which could be helpful to assess changes in cardiac output. The 4-quadrant plot and the polar plot have been described to compare the changes between 2 measurements performed under different conditions, and the direction of change by using different methods of measurements. However, the 4-quadrant plot and the polar plot present a number of limitations, with a risk of misinterpretation in routine clinical practice. We describe a new trend interchangeability method designed to objectively define the interchangeability of each change of a variable. Using the repeatability of the reference method, we classified each change as either uninterpretable or interpretable and then as either noninterchangeable, in the gray zone or interchangeable. An interchangeability rate can then be calculated by the number of interchangeable changes divided by the total number of interpretable changes. In this observational study, we used this objective method to assess cardiac output changes with 5 arterial pulse contour techniques (Wesseling's method, LiDCO, PiCCO, Hemac method, and Modelflow) in comparison with bolus thermodilution technique as reference method in 24 cardiac surgery patients. A total of 172 cardiac output variations were available from the 199 data points: 88 (51%) were uninterpretable, according to the first step of the method. The second step of the method, based on the 84 (49%) interpretable variations, showed that only 18 (21%) to 30 (36%) variations were interchangeable regardless of the technique used. None of pulse contour cardiac output technique could be interchangeable with bolus thermodilution to assess changes in cardiac output using the trend interchangeability method in cardiac surgery patients. Future studies may consider using this method to assess interchangeability of changes between different methods of measurements.

No MeSH data available.