Reproducibility of linear cardiac output measurement by Doppler ultrasound alone.

Abstract

Inclusion of a pig aorta in an artificial circulation with pulsed blood flow allowed correlation of minute distance, measured in the aorta by Doppler ultrasound, and absolute blood flow, measured by timed blood-volume collection. The correlation coefficient was 0.99 with a standard error of prediction that was 5.4% of the minute distance predicted at a standard flow rate of 5 litres per minute. The horizontal distance between 95% confidence limits for a single prediction expressed as a percentage of 5 litres per minute was 33%, and this corresponded to the range of flow rates of 1.65 litres per minute that could give rise to the same measurement. In 142 patients duplicate measurements of minute distance were made with repositioning of the ultrasound transducer between recordings. The mean difference between paired readings, expressed as a percentage of the average (SD) of each pair was 5.4 (4.7)%. Thus, the non-invasive measurement of linear cardiac output by Doppler ultrasound is similarly reproducible in vitro and in vivo and compares favourably with the measurement of volumetric cardiac output by thermodilution.

Determination of stroke volume and cardiac output during exercise: comparison of two-dimensional and Doppler echocardiography, Fick oximetry, and thermodilution.

“…Absolute and relative changes in peak velocity were lower in their study, reflecting lower peak heart rates and their use of consecutive rather than maximal velocity signals as was done here. The use of several consecutive velocity signals to calculate this velocity integral may be preferable, as noted by McLennan et al 21 However, we found acquisition of clean consecutive signals to be impractical at peak workloads with ytandard ergometers.…”

Method of assessing the reproducibility of blood flow measurement: factors influencing the performance of thermodilution cardiac output computers.

“…The roller pump we used closely simulates naturally occurring pulsatile flow, as judged by the similar appearances of the Doppler ultrasound recordings in vitro and in vivo. 38 In all three cardiac output computers accuracy and variability were significantly worse with pulsatile than with continuous flow. The pooled result of the predicted measurement at a continuous flow rate of 5 litres per minute was 5-6 (1 1) litres per minute and that during pulsatile flow was 8-1 (1-2) litres per minute.…”

Carvedilol but Not Metoprolol Reduces β-Adrenergic Responsiveness After Complete Elimination From Plasma In Vivo

“…LV SD is equivalent to LV stroke volume, which was used to calculate minute distance (MD), an equivalent of cardiac output (CO). 11 The following formulas were applied: fractional shortening (FS)ϭ(EDDϪESD)/EDD; mean velocity of circumferential fiber shortening (VCF)ϭFS/ET; HRcorrected VCF (VCF c )ϭVCFϫ(60/HR) 1/2 ; minute distance (MD)ϭHRϫstroke distance; and systemic vascular resistance (SVR)ϭmean arterial blood pressure/MD. Echocardiographic recordings were performed by the same investigator and evaluated offline in a blinded manner by 2 independent investigators using the EchoPac ultrasound software (GE Medical Systems).…”