Key result
Two-beam pulsed Doppler ultrasound strongly correlates with thermodilution for measuring cardiac output.
Why the study?
Two-beam pulsed Doppler ultrasound offers a simpler method to measure cardiac output but its accuracy and reproducibility compared to thermodilution needed evaluation.
Does two-beam pulsed Doppler ultrasound accurately measure cardiac output compared to thermodilution in ICU patients and volunteers?
Observational (n=58)
Blinded observers
Does two-beam pulsed Doppler ultrasound accurately measure cardiac output compared to thermodilution in ICU patients and volunteers?
Two-beam pulsed Doppler ultrasound provides a simpler, non-invasive method for measuring cardiac output with acceptable agreement to thermodilution, though it remains operator-dependent.
Answers are grounded in this paper and cite their sources.
Doppler CO estimation shows acceptable thermodilution agreement yet operator dependence; leaves open routine ICU adoption pending larger validation.
Two observers used two-beam pulsed Doppler ultrasound, equipped with a suprasternal probe, to measure cardiac output (QtDopp) in 38 ICU patients who had pulmonary artery catheters and in 20 adult volunteers. The two-beam pulsed Doppler method enables one device to measure simultaneously both aortic blood velocity and aortic diameter. Each observer was blind to the other's measurement and to the thermodilution cardiac output measurement (Qttd). Linear regression of the mean of both observer's QtDopp on Qttd showed QtDopp = 0.90.Qttd + 0.01 (see = 1.54 L/min, r = .90). Bias (+/- SD), defined as mean (QtDopp - Qttd) difference, was -0.69 +/- 1.55 L/min. Interobserver agreement was more variable in patients than volunteers; mean (observer 1 - observer 2) difference was 0.14 +/- 1.30 L/min in ICU patients and -0.09 +/- 0.92 L/min in volunteers. Two-beam pulsed Doppler ultrasound is a simpler method of measuring QtDopp than previous pulsed Doppler methods which measure separately the aortic diameter by echocardiography. Although its agreement with Qttd is close to other Doppler methods and has acceptable interobserver reproducibility, its accuracy remains operator-dependent.
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WONG et al. (1990) conducted an observational in ICU patients and healthy volunteers (n=58). Two-beam pulsed Doppler ultrasound vs. Thermodilution cardiac output measurement was evaluated on Cardiac output measurement agreement (QtDopp vs Qttd) (r = 0.90). Two-beam pulsed Doppler ultrasound showed strong correlation with thermodilution for measuring cardiac output, with a mean bias of -0.69 +/- 1.55 L/min.
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