OBJECTIVE: Do external Doppler indices correlated sufficiently to the peripheral resistance? METHODS: The resistance of 7 fetal sheep was measured inductively and was correlated to external Doppler measurements. The correlation of different indices and methods was compared. RESULTS: Only bloodflow velocities and the harmonic component index (HCI) yield good correlations (r > or = 7) to the peripheral resistance. PI, RI, S/D-Ratio and Vpeak/Vmean showed r-values from .47 to .59. None of the Doppler parameters reached the values of indices derived from the inductive flow probe. CONCLUSIONS: The blood flow velocities and the HCI seem to be superior to the classical indices in estimation of blood flow in the fetal aorta.
