Key result
Concentric beam Doppler noninvasively estimates cardiac output with moderate correlation of ~0.68 vs. invasive standards.
Why the study?
Noninvasive stand-alone Doppler assessment of cardiac output requires evaluation against invasive reference standards to determine accuracy and feasibility.
Does a concentric beam Doppler ultrasonic flowmeter accurately estimate cardiac output compared to invasive methods in patients undergoing invasive hemodynamic assessment?
Observational (n=54)
Does a concentric beam Doppler ultrasonic flowmeter accurately estimate cardiac output compared to invasive methods in patients undergoing invasive hemodynamic assessment?
The concentric beam Doppler ultrasonic flowmeter provides feasible noninvasive cardiac output estimates that correlate well with invasive methods under optimal conditions, though its utility is limited in difficult ICU scenarios.
Answers are grounded in this paper and cite their sources.
Noninvasive cardiac output estimates with this Doppler device require validation; leaves open clinical adoption pending larger studies.
A concentric beam Doppler ultrasonic flowmeter has been developed. This instrument has capacity for independent assessment of volumetric flow, as it determines flow cross-section area, stroke length, and pulse rate from the Doppler signals alone. The method is practically independent of the angle of interrogation. We used this device and obtained noninvasive estimates of cardiac output in 54 patients undergoing invasive assessment of cardiac output by thermodilution, Fick, or indicator dye methods (x). Correlations against pooled cardiac output reference standards ranged from r = .86 (y = .86x + 1.03) in 26 studies of high confidence to r = .45 (y = .30x + 2.62) in 17 studies under difficult conditions. The overall correlation was r = .68 (y = .63x + 1.49, n = 87). Noninvasive results of experienced and inexperienced operators were similar (r = .87). The instrument returned accurate assessments of heart rate (r = .83), but underestimated stroke length (r = .72) and appeared to be limited in the assessment of aortic diameters less than 28 or greater than 31 mm (r = .23). We conclude that stand-alone Doppler assessment of cardiac output is appealing and feasible, but difficult or impossible in many ICU scenarios. Further evolution of the concentric beam Doppler approach is needed and anticipated.
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Niclou et al. (1990) conducted an observational in Patients undergoing invasive assessment of cardiac output (n=54). Concentric beam Doppler ultrasonic flowmeter vs. Invasive assessment of cardiac output (thermodilution, Fick, or indicator dye methods) was evaluated on Correlation of cardiac output estimates against pooled reference standards (r = 0.68). Noninvasive estimation of cardiac output using a concentric beam Doppler ultrasonic flowmeter showed an overall correlation of r=0.68 compared to invasive reference standards.
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