Coupling between Regional Oxygen Saturation of the Brain and Vital Signs during Immediate Transition after Birth.

INTRODUCTION: The primary aim was to analyze any coupling of heart rate (HR)/arterial oxygen saturation (SpO2) and regional cerebral oxygen saturation (rScO2) and regional cerebral fractional tissue oxygen extraction (cFTOE) during immediate transition after birth in term and preterm neonates to gain more insight into interactions. METHODS: The present study is a post hoc analysis of data from 106 neonates, obtained from a prospective, observational study. Measurements of HR, SpO2, rScO2, and cFTOE were performed during the first 15 min after birth. The linear and nonlinear correlation were computed between these parameters in a sliding window. The resulting coupling curves were clustered. After clustering, demographic data of the clusters were de-blinded and compared. RESULTS: Due to missing data, 58 out of 106 eligible patients were excluded. Two clusters were obtained: cluster 1 (N = 39) and cluster 2 (N = 9). SpO2 had linear and nonlinear correlations with rScO2 and cFTOE, whereby the correlations with rScO2 were more pronounced in cluster 2. HR-rScO2 and HR-cFTOE demonstrated a nonlinear correlation in both clusters, again being more pronounced in cluster 2, whereby linear correlations were mainly absent. After de-blinding, the demographic data revealed that the neonates in cluster 2 had significantly lower gestational age (mainly preterm) compared to cluster 1 (mainly term). DISCUSSION: Besides SpO2, also HR demonstrated a nonlinear correlation with rScO2 and cFTOE in term and preterm neonates during immediate transition after birth. In addition, the coupling of SpO2 and HR with cerebral oxygenation was more pronounced in neonates with a lower gestational age.

Cerebrovascular autoregulation in preterm fetal growth restricted neonates.

OBJECTIVE: To investigate the effect of fetal growth restriction (FGR) on cerebrovascular autoregulation in preterm neonates during the first 3 days of life. DESIGN: Case-control study. SETTING: Neonatal intensive care unit of the Wilhelmina Children's Hospital, The Netherlands. PATIENTS: 57 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. METHODS: The 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. RESULTS: FGR 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). CONCLUSION: FGR 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.

Weighted Performance Metrics for Automatic Neonatal Seizure Detection Using Multiscored EEG Data.

In neonatal intensive care units, there is a need for around the clock monitoring of electroencephalogram (EEG), especially for recognizing seizures. An automated seizure detector with an acceptable performance can partly fill this need. In order to develop a detector, an extensive dataset labeled by experts is needed. However, accurately defining neonatal seizures on EEG is a challenge, especially when seizure discharges do not meet exact definitions of repetitiveness or evolution in amplitude and frequency. When several readers score seizures independently, disagreement can be high. Commonly used metrics such as good detection rate (GDR) and false alarm rate (FAR) derived from data scored by multiple raters have their limitations. Therefore, new metrics are needed to measure the performance with respect to the different labels. In this paper, instead of defining the labels by consensus or majority voting, popular metrics including GDR, FAR, positive predictive value, sensitivity, specificity, and selectivity are modified such that they can take different scores into account. To this end, 353 hours of EEG data containing seizures from 81 neonates were visually scored by a clinical neurophysiologist, and then processed by an automated seizure detector. The scored seizures were mixed with false detections of an automated seizure detector and were relabeled by three independent EEG readers. Then, all labels were used in the proposed performance metrics and the result was compared with the majority voting technique and showed higher accuracy and robustness for the proposed metrics. Results were confirmed using a bootstrapping test.

Interrelationship Between Broadband NIRS Measurements of Cerebral Cytochrome C Oxidase and Systemic Changes Indicates Injury Severity in Neonatal Encephalopathy.

Perinatal hypoxic ischaemic encephalopathy (HIE) is associated with severe neurodevelopmental problems and mortality. There is a clinical need for techniques to provide cotside assessment of the injury extent. This study aims to use non-invasive cerebral broadband near-infrared spectroscopy (NIRS) in combination with systemic physiology to assess the severity of HIE injury. Broadband NIRS is used to measure the changes in haemodynamics, oxygenation and the oxidation state of cytochrome c oxidase (oxCCO). We used canonical correlation analysis (CCA), a multivariate statistical technique, to measure the relationship between cerebral broadband NIRS measurements and systemic physiology. A strong relationship between the metabolic marker, oxCCO, and systemic changes indicated severe brain injury; if more than 60 % of the oxCCO signal could be explained by the systemic variations, then the neurodevelopmental outcome was poor. This boundary has high sensitivity and specificity (100 and 83 %, respectively). Broadband NIRS measured concentration changes of the oxidation state of cytochrome c oxidase has the potential to become a useful cotside tool for assessment of injury severity following hypoxic ischaemic brain injury.