THE INFLUENCE OF ACUTE HYPOXEMIA AND HYPOVOLEMIC HYPOTENSION OF NEURONAL BRAIN ACTIVITY MEASURED BY THE CEREBRAL FUNCTION MONITOR IN NEWBORN PIGLETS

Little is known about the cerebral electrical response to short period s of hypoxemia, hypotension and their combination. These conditions oc cur frequently in critically iu newborn infants; their cerebral electr ical activity can be registrated easily with the Cerebral Function Mon itor (CFM). Therefore we recorded on-line cortical electrical activity during hypoxemia and hypotension in 11 newborn piglets aged 13-18 day s. Hypoxemia was induced by reducing inspired oxygen fraction. Hypoten sion was induced by withdrawal of blood. The experimental groups were: Group I: arterial oxygen saturation (SaO(2)) 45-85%, group II: SaO(2) < 45%, group Ill. mean arterial pressure (MAP) 50-75 mmHg, group IV: MAP < 50 mmHG, group V: SAO(2) < 85% and MAP 50-75 mmHg and group VI: SaO(2) < 85% and MAP < 50 mmHg. CFM registrated normal cortical electr ical activity during periods of moderate or severe hypoxemia (group I and Il) and during isolated moderate hypotension (group III). The cort ical activity decreased significantly due to severe hypotension alone (group IV and combined hypotension and hypoxemia (group V and VI). Hyp otension has a more potent effect on cortical electrical activity than hypoxemia in the newborn piglet. Cerebral electrical activity does no t change during severe hypoxemia and moderate hypotension possibly due to cerebral now regulation. CFM recorded decreased cerebral electrica l activity during severe hypotension and hypotension with hypoxemia. C FM could provide invaluable data in severely ill newborns.