CEREBRAL-CIRCULATION ASSESSED BY TRANSCEPHALIC ELECTRICAL-IMPEDANCE DURING THE FIRST-DAY OF LIFE - A POTENTIAL PREDICTOR OF OUTCOME

Pulsatile changes in intracranial blood volume (transcephalic electric al impedance, Delta Z), arterial blood pressure (aBP) and respiration were studied during the first day after birth in 42 neonates with a bi rth weight of 1040-3850 g and gestational age of 26-36 weeks. The neur ological outcome was assessed at 1 year of age to study the predictive ability of Delta Z. Delta Z, EGG, respirogram and direct aBP were rec orded at 8-h intervals. Outcome was adverse in seven infants of whom t wo died from severe peri-intraventricular haemorrhage. PCO2 was higher (6.2 kPa) in the infants with adverse outcome than in those infants w ith favourable outcome (5.0 kPa) (P = 0.004). Blood glucose (4.5 vs. 3 .3 mmol/l, P = 0.030) and first day administration of fluid (80 vs. 63 ml/kg/day, P = 0.003) behaved, respectively. Of the infants receiving dopamine therapy, 60% had adverse outcome while only 11%, of those no t receiving dopamine had adverse outcome (P = 0.016). Of the infants w ith high diastolic blood pressure levels, 32% had adverse outcome, whi le none with low diastolic blood pressure levels had adverse outcome ( P = 0.031), Spectral analysis was used to examine signal variabilities in the frequency domain. During the first 24 h of life, the variabili ties of aBP and respiration were equal in all the infants. The high-fr equency Delta Z signal variability (1.50-4.00 Hz, heart rate level) wa s found to be lower in the infants with adverse outcome (330 units) th an in the infants with favourable outcome (1280 units, P = 0.017). The low Delta Z variability allowed us to assume that there is a decrease of pulsatile cerebral blood flow (CBF) in the infants with adverse ou tcome. We speculate that this may result from the 'no reflow phenomeno n', increased tissue pressure due to ischaemia and/or PIVH, the 'brain sparing effect' or constriction of main cerebral arteries due to incr eased pressure support or metabolic factors (PCO2, glucose). We believ e that transcephalic impedance provides a potential cot-side method fo r monitoring cerebral circulation in the neonatal period with an abili ty to predict outcome.