Relationship between early changes in cerebral blood volume and electrocortical activity after hypoxic–ischemic insult in newborn piglets

Abstract

Background: Early changes in cerebral hemodynamics and depressed electrocortical activity have been reported after a hypoxic–ischemic (HI) insult. However, the relationship between these two parameters is unclear. This study aimed to examine the relationship between changes in cerebral blood volume (CBV) and cerebral Hb oxygen saturation (ScO2) after a HI insult and the low amplitude-integrated electroencephalography (aEEG) duration concomitantly observed. Methods: Sixteen newborn piglets obtained within 24h of birth were used (n=3 controls). Thirteen piglets were subjected to a HI insult of 20-min low-amplitude aEEG (<5μV, LAEEG), after which a low mean arterial blood pressure (<70% of baseline) was maintained for 10min. We measured changes in CBV and ScO2 using near-infrared time-resolved spectroscopy (TRS) and cerebral electrocortical activities using aEEG until 6h after the insult. Results: A positive correlation was observed between the LAEEG duration and CBV increase, but not ScO2, after the insult. Conclusion: These results suggest that a larger increase in CBV reflected a more severe failure in cerebral circulation to maintain cell membrane action potentials, which induced a more extended recovery period of electrocortical activity after the insult. We conclude that an early increase in CBV and longer LAEEG indicate severe brain injury.