Postnatal Reversal of Discordancy of Cerebral Blood Flow Velocity (CBFV) in Growth Retarded (IUGR) Premature Neonates

Abstract 300 Poster Session IV, Tuesday, 5/4 (poster 266)

Asymmetry of CBFV in IUGR fetuses has been noted, with decreased pulsatility indices on the right. Such discordance between right and left blood flow has been attributed to intrauterine ductal shunting. We hypothesized that the asymmetry would be reversed postnatally given the physiologic reversal of ductal shunting in the early neonatal period. Methods We studied premature neonates ≤1750 gm., during the first week of life, with cerebral pulsed doppler studies of the middle cerebral artery. Right and left systolic flow velocities (SV); velocity time intervals (VTI) (reflective of cerebral blood flow); and pulsatility indices (PI) were assessed. Results: Appropriate for gestational age (AGA; n=67) and small for gestational age (SGA; n=18) were compared. Gestational age 31±2 vs 31±3wk was similar in both groups; birth weights were different by definition (1414±305 gm vs 979±331 gms). (Table) Conclusions/Speculation: These data demonstrate: 1- No asymmetry of cerebral flow in AGA infants. 2- An increase in right SV with a trend towards a decrease in left SV in SGA infants (RSV vs. LSV p=0.022). 3- An increased right pulsatility index in SGA infants. We speculate that SGA infants, in an effort to achieve "brain spaing" attempt to divert blood flow towards the brain. Given the proximity of the left subclavian artery to the ductus arteriosus and given that postnatal ductal shunting is left to right, CBFV postnatally is reversed with increased, rather than decreased, flow to the right.

Table 1 No caption available

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