Advanced dynamic Doppler flow of the pulmonary artery in a normal population: reference values from 18 to 41 weeks of gestation calculated by automatic Doppler waveform analysis.

ABSTRACT

OBJECTIVE: The aim of the present cross-sectional prospective study was to establish Doppler reference ranges for blood flow velocity waveforms (V max, V mean and V min) and resistance indices (PI, RI) of the fetal pulmonary arteries using the new pulsed-wave color advanced dynamic flow (ADF) Doppler technique. METHOD: Data were collected in 206 low-risk pregnancies at 18-41 weeks of gestation. The measurements were obtained in the proximal pulmonary artery near the first bifurcation in the absence of fetal body or breathing movements. RESULTS: The pulsatility index (PI) in the pulmonary artery showed mean increases of 2.43-3.59 between gestational weeks 18 and 42. A similar pattern was observed for the resistance index (RI) with increases of 0.79-0.90. Increases in systolic (V max), mean (V mean) and end diastolic (V min) blood flow velocities of 36.0-63.3, 10.8-19.9 and 5.71-7.53 cm/s, respectively, were noted during the observation interval. CONCLUSIONS: The ranges for blood flow velocities and impedance indices in the fetal pulmonary artery calculated by the authors may serve as reference values to help distinguish a normal patient population from patients carrying fetuses at high risk for neonatal lung disease in antenatal examinations.