Comparison of changes in cerebral and systemic perfusion between appropriate- and small-for-gestational-age infants during the first three days after birth

Purpose: The aims of the current study were to compare changes in cerebral and systemic perfusion in appropriate-for-gestational-age (AGA) and small-for-gestational-age (SGA) infants immediately after birth. Methods: Cerebral blood volume (CBV), cerebral Hb oxygen saturation (cSO2) and cerebral fractional tissue oxygen extraction (cFTOE) among 57 AGA infants and 30 SGA infants were monitored using a newly developed time-resolved spectroscopy system during the first 3 days of life. The left ventricular ejection fraction (LVEF), left ventricular cardiac output (LVCO) and E/e′ values were determined by three-dimensional echocardiography and tissue Doppler imaging performed simultaneously. Results: There were significant differences between the body weights of both the AGA and SGA infants, but not between the gestational age and head circumferences in both groups. Although CBV showed no significant difference between the groups, cSO2 was significantly higher and cFTOE was lower in SGA infants than in AGA infants. Hematocrit (Ht) levels were significantly higher and LVEF and LVCO were lower in SGA infants than in AGA infants. Negative correlation was observed between CBV and Ht levels in AGA infants, but not in SGA infants. Conclusions: The high Ht levels and vasoreactivity in SGA infants might be a compensatory mechanism in order to maintain oxygen delivery to the brain, which reflects the condition of chronic hypoxia during the fetal period and also reflects the weak contraction and low cardiac output of the left ventricle sustaining the relatively large brain from the fetal period to after birth.