Agreement of Bioreactance Cardiac Output Monitoring With Thermodilution in Healthy Standing Horses.

Klaus Hopster,Samuel D A Hurcombe

doi:10.3389/fvets.2021.701339

Klaus Hopster, Samuel D A Hurcombe

Open Access

https://doi.org/10.3389/fvets.2021.701339

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Abstract

Bioreactance is the continuous analysis of transthoracic voltage variation in response to an applied high frequency transthoracic current and was recently introduced for non-invasive cardiac output measurement (NICOM). We evaluated NICOM compared to thermodilution (TD) in adult horses. Six healthy horses were used for this prospective, blinded, experimental study. Cardiac output (CO) measurements were performed simultaneously using TD and the bioreactance method. Different cardiac output scenarios were established using xylazine (0.5 mg/kg IV) and dobutamine (1.5–3 mcg/kg/min). Statistical analysis was performed by calculating the concordance rate, performing a regression analysis, Pearson correlation, and Bland Altman. The TD-based CO and NICOM values were highly correlated for low, normal and high CO values with an overall correlation coefficient. A 4-quadrant plot showed an 89% rate of concordance. The linear regression calculated a relationship between NICOM and TDCO of Y = 0.4874 · X + 0.5936. For the corrected Bland Altman agreement, the mean bias and lower/upper limits of agreement were −0.26 and −3.88 to 3.41 L/min, respectively. Compared to TD, bioreactance- based NICOM showed good accuracy at induced low, normal, and high CO states in normal horses. Future studies performed under more clinical conditions will show if this monitor can help to assess hemodynamic status and guide therapy in horses in ICU settings and under general anesthesia.

Highlights

Measurement of cardiac output (CO) and, sometimes more importantly, changes in CO can be extremely useful when assessing circulatory function
The repeatability of the non-invasive cardiac output measurement (NICOM) measurements was satisfactory with a mean percentage error (MPE) of 8.7% for repeated baseline measurements
The administered drugs xylazine and dobutamine resulted in a CO range from 22 to 75 L/min for TD and CO range from 10.2 to 37.4 L/min for uncorrected NICOM over time during baseline measurements, after xylazine bolus and during dobutamine CRI (Figure 2)

Summary

Introduction

Measurement of cardiac output (CO) and, sometimes more importantly, changes in CO can be extremely useful when assessing circulatory function. Fast and reliable method to measure the CO is required for research purposes and for clinical settings and currently missing in equine medicine. Thermodilution technique as a measure of cardiac output (CO) was first introduced in the 1950’s and is since widely used in all kinds of species and recognized as a gold standard for evaluating and determination of the CO [1, 2]. In the clinical setting, it is considered being relatively invasive due to the necessity of placing intracardiac and -pulmonary artery catheters and often not utilized in equine patients [3]. There is a continuing search for a method of CO measurement that is less invasive than its predecessors.

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