Extracorporeal Arteriovenous Ultrasound Measurement of Cardiac Output in Small Children

Abstract

Editor’s Perspective What We Already Know about This Topic To date, there are not clinically practical, accurate, and precise noninvasive methods for measuring cardiac output in small children What This Article Tells Us That Is New This study describes a noninvasive method by which ultrasound can be used in small children to determine cardiac output with good precision After surgery in 43 small children for repair of atrial or ventricular septal defects, cardiac output measurements performed using saline bolus injections and ultrasound detection of the expected blood dilution showed similar precision for measuring cardiac output as a cardiac outputs measured using periaortic flow probe Background Technology for cardiac output (CO) and blood volume measurements has been developed based on blood dilution with a small bolus of physiologic body temperature saline, which, after transcardiopulmonary mixing, is detected with ultrasound sensors attached to an extracorporeal arteriovenous loop using existing central venous and peripheral arterial catheters. This study aims to compare the precision and agreement of this technology to measure cardiac output with a reference method, a perivascular flow probe placed around the aorta, in young children. The null hypothesis is that the methods are equivalent in precision, and there is no bias in the cardiac output measurements. Methods Forty-three children scheduled for cardiac surgery were included in this prospective single-center comparison study. After corrective cardiac surgery, five consecutive repeated cardiac output measurements were performed simultaneously by both methods. Results A total of 215 cardiac output measurements were compared in 43 children. The mean age of the children was 354 days (range, 30 to 1,303 days), and the mean weight was 7.1 kg (range, 2.7 to 13.6 kg). The precision assessed as two times the coefficient of error was 3.6% for the ultrasound method and 5.0% for the flow probe. Bias (mean COultrasound 1.28 l/min − mean COflow probe 1.20 l/min) was 0.08 l/min, limits of agreement was ±0.32 l/min, and the percentage error was 26.6%. Conclusions The technology to measure cardiac output with ultrasound detection of blood dilution after a bolus injection of saline yields comparable precision as cardiac output measurements by a periaortic flow probe. The difference in accuracy in the measured cardiac output between the methods can be explained by the coronary blood flow, which is excluded in the cardiac output measurements by the periaortic flow probe.

Fluid responsiveness in the pediatric population

“…However, inter-observer and intra-observer variability should be considered during echocardiographic measurements [53]. A more accurate method is placement of a perivascular flow probe around the aorta [54]. However, the application of this method is highly limited.…”

Estimation of intracardiac shunts in young children with a novel indicator dilution technology

“…It is easily applied in young children with less technical limitations, as it only requires a central and an arterial line (often in place in critically ill patients), uses body-temperature saline as an indicator in small amounts, involves no blood loss and does not require invasive control of ventilation or sedation/anesthesia when catheters are in place. COstatus has performed well in pediatric cardiac output comparison studies and could help bridge the gap between invasive hemodynamic monitors and non-invasive methods in the future 12,[25][26][27] . In our opinion, the COstatus monitor is not a technique that can replace echocardiography in the evaluation and the clinical decision-making regarding need for cardiac intervention.…”

“…To reject the null hypothesis, the sample size for this study with an alpha error of p 0.05 and power of 0.90 needed to be at least n = 28. The final number of patients was related to the fact that a higher number of patients was needed for a simultaneous cardiac output comparison study 25 .…”

Indirect Calorimetry Overestimates Oxygen Consumption in Young Children: Caution is Advised Using Direct Fick Method as a Reference Method in Cardiac Output Comparison Studies

“…Forty-two patients undergoing congenital cardiac surgery were included in this study which was a part of a larger ongoing single center prospective method comparison study [11]. The study was approved and registered by the Ethics Committee of Lund University, Sweden (Dnr 2,013,636).…”