Abstract
Evaluation of hemodynamics in patients with acute myocardial infarction is crucial. In clinical practice, the comparison of a new measurement technique with an established one is often needed to see whether they agree sufficiently for the new to replace the old. Such investigations are often analyzed inappropriately, notably by using correlation coefficients. Our objective is to present an alternative approach, suggested by D. G. Altman and J. M. Bland, based on graphical techniques and simple calculations, for evaluation of the agreement of two methods--intermittent thermodilution (recognized and accepted as a "gold standard" for hemodynamic monitoring) and impedance cardiography (newly introduced method). A total of 34 patients (20 (58.8%) men and 14 (41.2%) women) were investigated according to the study protocol at Kaunas University of Medicine Hospital. A prospective controlled study was designed to compare two different methods--intermittent thermodilution and impedance cardiography--of cardiac output measurement simultaneously in patients with acute myocardial infarction. Statistical analysis was performed with Bland-Altman and linear regression. A total of 34 paired measurements were carried out in 34 patients at the initiation of hemodynamic monitoring and 30 paired measurements in 32 patients after subsequent improvement or stabilization of clinical status. Correlation coefficient ranged from 0.37 to 0.98. Bland-Altman analysis is an alternative method for assessing the agreement between two methods of clinical measurement. According to our data, noninvasive technique--impedance cardiography--is a reliable method for hemodynamic monitoring in noncomplicated cases of acute myocardial infarction.
Highlights
In clinical practice, it is usually expected to have precise values of different parameters, for example cardiac output or stroke volume where direct measurements without adverse effects are difficult or impossible [1]
Bland–Altman analysis is an alternative method for assessing the agreement between two methods of clinical measurement
cardiac output (CO) values obtained by two different methods of hemodynamic monitoring are presented in Table
Summary
It is usually expected to have precise values of different parameters, for example cardiac output or stroke volume where direct measurements without adverse effects are difficult or impossible [1]. Almost all direct measurements are obtained by the application of invasive techniques and procedures. Priority is given for noninvasive methods, as for more convenient and safe ones. The main problem is validation of noninvasive techniques and further legalization for clinical application. If a new method agrees sufficiently well with the old, the old may be replaced [1]. Many statistical approaches have been proposed for the evaluation of correlation between two different methods
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