Validation study of the accuracy of echocardiographic measurements of systemic blood flow volume in newborn infants.
BACKGROUND
The echocardiographic assessment of circulatory function in sick newborn infants has the potential to improve patient care. However, measurements are prone to error and have not been sufficiently validated. Phase-contrast magnetic resonance imaging (MRI) provides highly validated measures of blood flow and has recently been applied to the newborn population. The aim of this study was to validate measures of left ventricular output and superior vena caval flow volume in newborn infants.


METHODS
Echocardiographic and MRI assessments were performed within 1 working day of each other in a cohort of newborn infants.


RESULTS
Examinations were performed in 49 infants with a median corrected gestational age at scan of 34.43 weeks (range, 27.43-40 weeks) and a median weight at scan of 1,880 g (range, 660-3,760 g). Echocardiographic assessment of left ventricular output showed a strong correlation with MRI assessment (R(2) = 0.83; mean bias, -9.6 mL/kg/min; limits of agreement, -79.6 to +60.0 mL/kg/min; repeatability index, 28.2%). Echocardiographic assessment of superior vena caval flow showed a poor correlation with MRI assessment (R(2) = 0.22; mean bias, -13.7 mL/kg/min; limits of agreement, -89.1 to +61.7 mL/kg/min; repeatability index, 68.0%). Calculating superior vena caval flow volume from an axial area measurement and applying a 50% reduction to stroke distance to compensate for overestimation gave a slightly improved correlation with MRI (R(2) = 0.29; mean bias, 2.6 mL/kg/min; limits of agreement, -53.4 to +58.6 mL/kg/min; repeatability index, 54.5%).


CONCLUSIONS
Echocardiographic assessment of left ventricular output appears relatively robust in newborn infant. Echocardiographic assessment of superior vena caval flow is of limited accuracy in this population, casting doubt on the utility of the measurement for diagnostic decision making.
Imperial College and MRC Clinical Sciences Centre, London, United Kingdom; Patologia e Terapia Intensiva Neonatale, Università degli Studi di Verona, Verona, Italy.
Benjamim
B
Ficial
Anna E
AE
Finnemore
David J
DJ
Cox
Kathryn M
KM
Broadhouse
Anthony N
AN
Price
Giuliana
G
Durighel
Georgia
G
Ekitzidou
Joseph V
JV
Hajnal
A David
AD
Edwards
Alan M
AM
Groves
D001810:Blood Volume / Q000502:physiology*; D001811:Blood Volume Determination / Q000379:methods*; D004452:Echocardiography / Q000379:methods; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D006801:Humans; D007231:Infant, Newborn / Q000502:physiology*; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014683:Vena Cava, Superior / Q000000981:diagnostic imaging* / Q000502:physiology*; D016277:Ventricular Function, Left / Q000502:physiology*
Echocardiography; LOA; LVO; Left ventricular output; Limits of agreement; MRI; Magnetic resonance imaging; PC; Phase-contrast; Phase-contrast MRI; Preterm infants; RI; Repeatability index; SVC; Superior vena caval; VTI; Velocity-time integral