In vivo validation of automatic cardiac output measurement from color flow Doppler velocity profile

Automated cardiac output measurements by ultrasound are inaccurate at high cardiac outputs

“…The present study confirms the finding that there exists a significant correlation between cardiac output values measured by ACM and TD, as has been reported in the literature 4,5 . In contrast to these studies, however, we also found a major (ACM 2 TD) difference, confirming the recent similar reported by Trindade et al 7 .…”

“…It is difficult to determine exactly why the present results are different from two 4,5 of the three previous studies 4,5,7 . The main difference is that measurements were carried out over a larger range of cardiac outputs (3.4±15.3 L/min).…”

“…The literature reports an excellent correlation between the non-invasive ACM method and the invasive TD method 4,5 . However, previously reported studies were performed in non-pregnant individuals over a fairly narrow (3.5± 7.3 L/min) cardiac output range 5 , lower than anticipated in healthy pregnant women, in whom cardiac output is known to be increased by approximately 40%, as well as in treated pre-eclamptic women 1,6 .…”

Automated Volumetric Flow Quantification Using Angle‐Corrected Color Doppler Image

“…In an effort to improve upon the PW‐Doppler method, researchers have proposed new approaches for calculating stroke volume from color Doppler images (CDI) 9–11 . The CDI is a composite image that shows both the 2D image of intracardiac structures as well as the real‐time blood velocity profile.…”

“…Volumetric flow is computed from CDIs by spatially and temporally integrating blood velocities encoded in each image throughout the ejection period. Although studies have shown a good correlation between the volumetric flow measured from CDI and other clinical techniques, there has been a consistent underestimation in flow by CDI, presumably due to the angle of incidence between the direction of ultrasound beam and the direction of blood flow 9 , 12,13 …”