Forster DE, et al. – This study was meant to assess the range of cerebral blood flow velocities (CBFVs) and Doppler indices of cerebrovascular resistance in normal–term neonates as a baseline for a study of hypoxic–ischaemic encephalopathy. In investigations, no correlation was observed between Doppler indices and gestation. However, less variation and smaller standard deviation of CBFV's was associated with a smaller angle of insonation.

Methods

• In the anterior and middle cerebral arteries (ACA and MCA) of 38 normal neonates, the CBFVs, resistive index (RI) and pulsatility index (PI) were measured.

Results

• The mean peak systolic, end diastolic and time–averaged velocities (PSV, EDV and TAV) were 36.3 ± 6.6, 12.4 ± 3.9 and 22.0 ± 4.0 cm/s (ACA) and 41.4 ± 13.2, 13.0 ± 5.5 and 25.8 ± 7.9 cm/s (MCA), respectively.
• All CBFVs in the ACA correlated with gestation; only EDV was correlated to post–natal age.
• The RI in the ACA (0.67 ± 0.06) and MCA (0.68 ± 0.07) were correlated (r = 0.72, P < 0.001).
• RI correlated to post–natal age.
• Two infants with RI < 0.55 were both fed within 25 mins of the study.
• RI correlated with post–prandial time (dichotomous, pivot 25 min).
• The mean PI was 1.11 ± 0.18 (ACA) and 1.17 ± 0.23 (MCA).
• Correlations were observed with post–natal age and post–prandial time (dichotomous).
• The average angle of insonation was greater in the ACA than in the MCA (median of 5° vs. 18°).