The Effects of Preterm Birth on Cerebral Pressure‐Flow Dynamics

Abstract

Altered cortical and neurodevelopmental outcomes have been described following very preterm birth and imparied blood pressure (BP) and cerebral blood flow regulation have been implicated as possible mechanisms. However, whether haemodynamic impairment persists into early childhood following preterm birth remains unclear. To test the hypothesis that cerebrovascular dysfunction persists in early childood (age 6.6 yrs ±0.8) following preterm brith, we recorded BP and middle cerebral blood velocity (MCAv) in 10 preterm children (5 males, mean gestastion age at birth =32.2 weeks ±2.7) and 10 children born at term (5 males, mean gestation age at birth =39.7 weeks ±1.0) under spontaneous baseline conditions. Cerebral BP-MCAv dynamics were assessed using linear transfer function analysis. Additionally, we applied Granger's causlity test to determine the direction and strength of BP-MCAv interactions using Vector Autoregressive Moving Average Models. Results showed that compared to term children, BP-MCAv coherence was higher in preterm females (0.35±0.079 vs. 0.58±0.086, p=0.08) but similar in males (0.41±0.072 vs. 0.049±0.10, p=0.53). The average directionality index was similar between term and preterm children but the standard deviation was greater in preterm children (-7.2±13.33 vs -7.8±32.25). Further, the directionality index was positively correlated to the transfer function coherence (r=48, p<0.05). These results indicate that preterm females may have impaired cerebrovacular regulation and that, as a group, preterm children are more likley to exhibit pressure-flow dynamics that are dominated by either BP or cerebral blood flow.