Investigations concerning the application of the cross-correlation method in cardiac output measurements

Abstract

BackgroundIn spite of numerous non-invasive examinations the “gold clinical standard” of cardiac output measurements is the invasive pulmonary artery catheterization by means of the Swan-Ganz catheter and the application of the thermodilution method to estimate the blood flow. The results obtained by means of thermodilution are sensitive to many physical and biological disturbances. The unreliability of this method amounts to 20-45% and depends on the given variant of the method. Therefore some other method, more accurate and resistant to disturbances, was looked for. This paper presents a new approach to cardiac output measurements, based on cross-correlation signal analysis. The goal of investigations was to verify experimentally the application of the cross-correlation method of cardiac output measurements.ResultsIn 99.2% of the examined cases the extreme of the cross-correlation function was easy to be estimated by numerical algorithms. In 0,8% of the remaining cases (with a plateau region adjacent to the maximum point) numerical detection of the extreme was inaccurate. The typical unreliability of the investigated method amounted o 5.1% (9.8% in the worst case). Investigations performed on a physical model revealed that the unreliability of cardiac output measurements by means of the cross-correlation method is 3–5 times better than in the case of thermodilution.ConclusionsThe performed investigations and theoretical analysis have shown, that the cross-correlation method may be applied in cardiac output measurements. This kind of measurements seems to be more accurate and disturbance-resistant than clinically applied thermodilution.

Estimation of cardiac output and systemic vascular resistance using a multivariate regression model with features selected from the finger photoplethysmogram and routine cardiovascular measurements

“…Some of the reasons for the underutilization of these non-invasive methods include the requirement of a trained operator, the cost of the required specialized equipment and their disposable components, as well as the accuracy, precision and reproducibility of the measurement methods. As an example, the Doppler ultrasound method requires well-trained personnel to operate [12] and the uncertainty of the flow profile and diameter of the blood vessel contributes to the inaccuracy of the method [8,13] and the bioimpedance method has demonstrated poor results in numerous validation studies in critically ill and septic patients [8]. The minimally invasive pulse contour analysis technique requires continuous measurement of the arterial pulse pressure waveform from a peripheral artery (where the waveform itself can be measured invasively or non-invasively) as well as calibration against a standard method (such as transpulmonary thermodilution).…”

The Influence of Limited Dynamic Response of the Indicator Detector in a Swan-Ganz Catheter on the Overestimation of Cardiac Output Measurement By Means of Thermodilution

“…The results of CO measurements by means of thermodilution are sensitive to numerous disturbances with a different physical nature. It has been pointed out in many papers [1,[5][6][7] that the most significant reasons of the uncertainty of thermodilution are: inaccuracy of measurements of the indicator and blood temperature, instability of the volume of the indicator, variable thermodynamic parameters of blood (e.g. caused by intravenous injection of medicines), diseases of the valves, intracardiac leaks of blood, spontaneous ventilation, arrhythmia, displacement of the catheter during the examination and thermal instability of the patient (e.g.…”