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Continuous wave Doppler cardiac output: use in pediatric patients receiving inotropic support
W R Morrow1, D J Murphy, D J Fisher
1Little Frank Abercrombie Section of Cardiology, Baylor College of Medicine, Houston, Texas.
Insights
Continuous wave Doppler echocardiography accurately estimates cardiac output in critically ill children. Measuring aortic diameter at the aortic valve annulus provides the best correlation with invasive methods, aiding hemodynamic management.
Area of Science:
- Pediatric Cardiology
- Echocardiography
- Hemodynamics
Background:
- Doppler estimates of cardiac output correlate well with invasive methods in stable patients.
- Validation in hemodynamically unstable pediatric patients is lacking.
Purpose of the Study:
- To assess the accuracy of continuous wave Doppler echocardiography for cardiac output estimation in hemodynamically unstable pediatric patients.
- To evaluate the impact of aortic diameter measurement site on Doppler accuracy.
Main Methods:
- 27 simultaneous Doppler and thermodilution comparisons were performed in 12 pediatric patients.
- Doppler cardiac output was calculated using aortic diameter measured at three sites: aortic valve annulus, aortic root, and ascending aorta.
- Patients received inotropic support and afterload-reducing agents.
Main Results:
- A close correlation was observed between Doppler and thermodilution techniques across all measurement sites.
- Aortic valve annulus diameter measurement yielded the best correlation (r = 0.94) and least variability.
- Percent change in Doppler stroke volume correlated well with thermodilution stroke volume (r = 0.87) for serial determinations.
Conclusions:
- Continuous wave Doppler echocardiography is a useful method for estimating cardiac output in hemodynamically unstable pediatric patients.
- Measurement site of aortic diameter significantly impacts accuracy, with the aortic valve annulus being optimal.
- Doppler is effective in detecting changes in cardiac output during hemodynamic support.
Abstract:
Doppler estimates of cardiac output have been shown to correlate closely with invasive measurement of cardiac output in hemodynamically stable adults and children. However, this method has not been validated in hemodynamically unstable pediatric patients. To assess the accuracy of continuous wave Doppler echocardiography in pediatric patients with unstable hemodynamics, we performed 27 simultaneous Doppler and thermodilution comparisons in 12 pediatric patients receiving inotropic support and afterload-reducing agents. Doppler cardiac output was calculated using aortic diameter measured from long-axis two-dimensional echocardiograms at three different sites: the aortic valve anulus, the aortic root at the sinuses of Valsalva, and the ascending aorta. For all measurements, there was a close correlation between Doppler and thermodilution techniques. However the site of measurement of aortic diameter had a significant impact on the strength on the correlation and the variability between Doppler and thermodilution. The best correlation and least variability were obtained using the aortic valve anulus diameter (r = 0.94). On serial determinations, percent change in Doppler stroke volume correlated well with thermodilution stroke volume (r = 0.87) and was useful in detecting both direction and magnitude of change in thermodilution stroke volume. Despite the administration of positive inotropic and afterload-reducing agents, Doppler cardiac output is a useful method for estimating cardiac output in hemodynamically unstable pediatric patients.