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ObjectiveTo investigate the effect of fetal growth restriction (FGR) on cerebrovascular autoregulation in preterm neonates during the first 3 days of life.DesignCase–control study.SettingNeonatal intensive care unit of the Wilhelmina Children’s Hospital, The Netherlands.Patients57 FGR (birth weight <10th percentile) and 57 appropriate for gestational age (AGA) (birth weight 20th–80th percentiles) preterm neonates, matched for gender, gestational age, respiratory and blood pressure support.MethodsThe correlation between continuously measured mean arterial blood pressure and regional cerebral oxygen saturation was calculated to generate the cerebral oximetry index (COx). Mean COx was calculated for each patient for each postnatal day. The percentage of time with impaired autoregulation (COx>0.5) was also calculated.ResultsFGR neonates had higher mean COx values than their AGA peers on day 2 (0.15 (95% CI 0.11 to 0.18) vs 0.09 (95% CI 0.06 to 0.13), p=0.029) and day 3 (0.17 (95% CI 0.13 to 0.20) vs 0.09 (95% CI 0.06 to 0.12), p=0.003) of life. FGR neonates spent more time with impaired autoregulation (COx value >0.5) than controls on postnatal day 2 (19% (95% CI 16% to 22%) vs 14% (95% CI 12% to 17%), p=0.035) and day 3 (20% (95% CI 17% to 24%) vs 15% (95% CI 12% to 18%), p=0.016).ConclusionFGR preterm neonates more frequently display impaired cerebrovascular autoregulation compared with AGA peers on days 2 and 3 of life which may predispose them to brain injury. Further studies are required to investigate whether this impairment persists beyond the first few days of life and whether this impairment is linked to poor neurodevelopmental outcome.

IntroductionElevated carbon dioxide (CO2) blood levels have a depressant effect on the central nervous system and can lead to coma in adults. Less is known about the effect of CO2on the neurological function of infants.ObjectiveTo describe the effect of acute severe hypercapnia (PaCO2>70 mm Hg) on amplitude-integrated electroencephalography (aEEG) and cerebral oxygenation in newborn infants.Study designObservational study of full-term and preterm infants with acute severe hypercapnia (identified by arterial blood gas measurements), monitored with aEEG. Visual analysis of the aEEG was performed in all infants. In preterm infants <32 weeks postmenstrual age (PMA), analysis of two-channel EEG was performed. Mean spontaneous activity transients (SAT) rate (SATs/min), interval between SATs (ISI in seconds) and the ISI percentage (ISP) were calculated for 10-min periods before, during and after hypercapnia. Mean regional cerebral oxygen saturation (rScO2) and fractional tissue oxygen extraction (FTOE) measured with near-infrared spectroscopy were also calculated for these periods.ResultsTwenty-five infants (21 preterm, 4 full-term) comprising 32 episodes of acute severe hypercapnia were identified. Twenty-seven episodes were accompanied by a transient aEEG depression. Twenty-two episodes in 15 preterm infants <32 weeks PMA were quantitatively analysed. During hypercapnia, SAT rate decreased and ISI and ISP increased significantly. No significant change occurred in rScO2or FTOE during hypercapnia.ConclusionProfound depression of brain activity due to severe hypercapnia is also seen in infants. It can be recognised by an acute depression of the aEEG, without clinically detectable changes in cerebral oxygenation.

Near-infrared spectroscopy is a noninvasive method for monitoring brain oxygenation. The aim of the study was to investigate differences between cerebral oxygenation in different brain regions in newborns. In a prospective study, we monitored simultaneously left and right frontoparietal and temporo-occipital regional cerebral oxygen saturation (rScO2) and cerebral fractional tissue extraction (cFTOE: (arterial oxygen saturation (SaO2) − rScO2)/SaO2) using near-infrared spectroscopy. A 2-h measurement was performed on d 1, 3, and 7. We included 10 very preterm (GA <32 wk), 10 preterm (GA: 32–37 wk), and 10 term (GA ≥37 wk) neonates. Limits of agreement for difference of the measurements between different places were determined using the Bland-Altman method. In all subgroups, the rScO2and cFTOE values at different regions were not different. Limits of agreement were between ±14 and ±18% for all subgroups. Left-to-right differences were small between different postnatal and GAs. A decrease and increase over time for rScO2and cFTOE values was detected for all four brain regions, most pronounced for infants with GA <32 wk. Cerebral oxygenation in stable preterm and term neonates seems not to differ between different regions of the brain during the early neonatal period. However, variability of individual measurements was quite high as indicated by large limits of agreement.

In a prospective study, we monitored simultaneously left and right parieto-frontal-cerebral oxygen saturation (rScO2) and cerebral fractional tissue oxygen extraction (cFTOE) using near-infrared spectroscopy in 36 very preterm neonates during the first 3 d of life. Simple regression analysis showed a close correlation between left and right rScO2(r = 0.89, p < 0.01) and cFTOE (r = 0.88, p < 0.01), respectively. The Bland and Altman-determined limits of agreement found overall limits of agreement of -8.5 to +9.5% and of -0.10 to +0.093% between left and right for rScO2and for cFTOE, respectively. However, we found that during stable systemic oxygenation (i.e., arterial oxygen saturation [SaO2between 85 and 97%]) the limits of agreement between left and right improved from -7.8 to +8.2% and -0.088 to +0.084 for rScO2and cFTOE, respectively (all p < 0.05). We conclude that bilateral near-infrared spectroscopy–measured rScO2and cFTOE can reveal differences up to 10% between left and right hemisphere, especially during unstable arterial saturations, which may indicate uneven cerebral oxygenation.