Cardiac Output Measurement Using the Ultrasonic Cardiac Output Monitor: A Validation Study in Newborn Infants

Abstract

<b><i>Objectives:</i></b> We aimed to determine the accuracy and validity of the Ultrasonic Cardiac Output Monitor (USCOM) measurements of cardiac output (CO) compared to echocardiography in newborn infants, and the inter-rater agreement of USCOM measurements. <b><i>Methods:</i></b> In a single-center study we prospectively evaluated neonates undergoing an echocardiographic evaluation. USCOM measurements of CO were obtained at the pulmonary and aortic valve by 2 physicians blinded to the echocardiographic results. All echocardiographic measurements were performed blinded to USCOM measurements. We first enrolled an ascertainment cohort which was subsequently validated in an independent new cohort. Agreement between echocardiography and USCOM methods was assessed by Bland-Altman analysis. Intra-class correlation coefficients (ICC) assessed the agreement between the 2 operators. The ascertainment cohort correction factors were applied in a second validation cohort and agreement of the calibrated measures evaluated with repeat Bland-Altman comparisons. <b><i>Results:</i></b> A total of 50 infants were enrolled in the initial cohort and 15 in the validation cohort. There was a high degree of correlation between the USCOM operators (ICC = 0.975). USCOM measurements of CO were significantly higher compared to echocardiography (left ventricular output bias 95 ± 52 mL/kg/min and right ventricular output bias 64 ± 30 mL/kg/min). There was no difference in the subgroup of infants with and without a ductus arteriosus. After the correction was applied to the validation cohort, there was no longer a significant difference between the measures. <b><i>Conclusions:</i></b> CO measured by USCOM consistently overestimated the results obtained from echocardiography. USCOM is not adequate to provide absolute estimates of CO. However, it may allow longitudinal hemodynamic assessment of sick neonates.

Evaluation of hemodynamics in healthy term neonates using ultrasonic cardiac output monitor

“…In particular it Fig. 3 (a [6]. In our study, we show that USCOM may be considered reliable since we find concordance between measures by USCOM and echocardiography for what concerns PDA patients.…”

“…Furthermore, LGA infants are often born from diabetic mothers and the impact of maternal diabetes on fetal heart is well known as it is known the higher incidence of cardiac malformations in this cohort [11]. In our dataset only 1 out of 6 LGA was born from diabetic mother (gestational diabetes). However, it is important to underline that during postnatal adaptation phase, there are major changes in cardiomyocyte metabolism.…”

“…Recently published data on newborns show that USCOM may over-estimate CO compared to echocardiograph. However, the authors confirm that USCOM may be reliable if used for repetitive measures or if appropriate corrections are made [ 6 ]. In our study, we show that USCOM may be considered reliable since we find concordance between measures by USCOM and echocardiography for what concerns PDA patients.…”

“…Despite being widely used on adult patients, USCOM applicability to newborn is still debated. In particular it is debated how much USCOM measures agree with traditional echocardiography measure in determining cardiac output with contrasting data in literature [ 5 , 6 , 16 , 17 ]. Recently published data on newborns show that USCOM may over-estimate CO compared to echocardiograph.…”

“…A Chinese group published some years ago a study in which they monitored cardiac output in healthy term infants during transitional phase, starting from 4 h after birth up to 8 h of life [5]. In a recent work USCOM was used on newborn in comparison to echocardiography and it was shown to over-estimate CO [6]. In this study we aimed to confirm previously published data on healthy newborn population but extending the analysis to longer time-points, and we aimed to assess the impact of several commonly found conditions on the transition phase.…”