Cardiac output by pulsed Doppler in neonates using the apical window

Area of Science:

• Pediatric Cardiology
• Medical Imaging
• Neonatal Physiology

Background:

• Accurate measurement of cardiac output is crucial for assessing hemodynamic status in neonates.
• Non-invasive methods are preferred for pediatric cardiac assessment.
• Doppler echocardiography offers a non-invasive approach to evaluate blood flow dynamics.

Purpose of the Study:

• To evaluate the accuracy of range-gated Doppler echocardiography for measuring cardiac output in healthy neonates.
• To compare cardiac index values obtained using maximal versus modal flow velocities.
• To determine the optimal measurement site (left ventricular outflow tract vs. ascending aorta) for cardiac output assessment.

Main Methods:

• Cardiac output was measured in 18 healthy neonates using range-gated Doppler echocardiography and 2D echocardiography via an apical approach.
• Spectral analysis was used to compare maximal and modal flow velocities.
• Measurements were taken in the left ventricular outflow tract and ascending aorta.

Main Results:

• Cardiac index (cardiac output per kg body weight) averaged 170 +/- 45 ml/min/kg (maximal velocity) and 133 +/- 39 ml/min/kg (modal velocity) in the left ventricular outflow tract (p < 0.05).
• In the ascending aorta, cardiac index averaged 198 +/- 73 ml/min/kg (maximal velocity) and 167 +/- 58 ml/min/kg (modal velocity).
• Maximal flow velocities in the ascending aorta showed the closest agreement with published invasive and non-invasive data.

Conclusions:

• Range-gated Doppler echocardiography is a viable method for assessing cardiac output in neonates.
• Measuring maximal flow velocities in the ascending aorta appears to provide the most reliable estimates of cardiac index in this population.
• This technique can aid in non-invasive hemodynamic monitoring of neonates.