The SafeBoosC II randomized trial: treatment guided by near-infrared spectroscopy reduces cerebral hypoxia without changing early biomarkers of brain injury

Effect of Cerebral Oximetry-Guided Treatment on Brain Injury in Preterm Infants as Assessed by Magnetic Resonance Imaging at Term Equivalent Age: An Ancillary SafeBoosC-III Study

INTRODUCTION

The SafeBoosC-III trial investigated the effect of cerebral oximetry-guided treatment in the first 72 h after birth on mortality and severe brain injury diagnosed by cranial ultrasound in extremely preterm infants (EPIs). This ancillary study evaluated the effect of cerebral oximetry on global brain injury as assessed by magnetic resonance imaging (MRI) at term equivalent age (TEA).

METHODS

MRI scans were obtained between 36 and 44.9 weeks PMA. The Kidokoro score was independently evaluated by two blinded assessors. The intervention effect was assessed using the nonparametric Wilcoxon rank sum test for median difference and 95% Hodges-Lehmann (HL) confidence intervals (CIs). The intraclass correlation coefficient (ICC) was used to assess the agreement between the assessors.

RESULTS

A total of 210 patients from 8 centers were included, of whom 121 underwent MRI at TEA (75.6% of alive patients): 57 in the cerebral oximetry group and 64 in the usual care group. There was an excellent correlation between the assessors for the Kidokoro score (ICC agreement: 0.93, 95% CI: 0.91-0.95). The results showed no significant differences between the cerebral oximetry group (median 2, interquartile range [IQR]: 1-4) and the usual care group (median 3, IQR: 1-4; median difference -1 to 0, 95% HLCI: -1 to 0; p value 0.1196).

CONCLUSIONS

In EPI, the use of cerebral oximetry-guided treatment did not lead to significant alterations in brain injury, as determined by MRI at TEA. The strong correlation between the assessors highlights the potential of the Kidokoro score in multicenter trials.

Predicting the effectiveness of drugs used for treating cardiovascular conditions in newborn infants

BACKGROUND

Cardiovascular support (CVS) treatment failure (TF) is associated with a poor prognosis in preterm infants.

METHODS

Medical charts of infants with a birth weight <1500 g who received either dopamine (Dp) or dobutamine (Db), were reviewed. Treatment response (TR) occurred if blood pressure increased >3rd centile for gestational age or superior vena cava flow was maintained >55 ml/kg/min, with decreased lactate or less negative base excess, without additional CVS. A predictive model of Dp and Db on TR was designed and the impact of TR on survival was analyzed.

RESULTS

Sixty-six infants (median gestational age 27.3 weeks, median birth weight 864 g) received Dp (n = 44) or Db (n = 22). TR occurred in 59% of the cases treated with Dp and 31% with Db, p = 0.04. Machine learning identified a model that correctly labeled Db response in 90% of the cases and Dp response in 61.4%. Sixteen infants died (9% of the TR group, 39% of the TF group; p = 0.004). Brain or gut morbidity-free survival was observed in 52% vs 30% in the TR and TF groups, respectively (p = 0.08).

CONCLUSIONS

New predictive models can anticipate Db but not Dp effectiveness in preterm infants. These algorithms may help the clinicians in the decision-making process.

IMPACT

Failure of cardiovascular support treatment increases the risk of mortality in very low birth weight infants. A predictive model built with machine learning techniques can help anticipate treatment response to dobutamine with high accuracy. Predictive models based on artificial intelligence may guide the clinicians in the decision-making process.

Early EEG-burst sharpness and 2-year disability in extremely preterm infants

BACKGROUND

Automated computational measures of EEG have the potential for large-scale application. We hypothesised that a predefined measure of early EEG-burst shape (increased burst sharpness) could predict neurodevelopmental impairment (NDI) and mental developmental index (MDI) at 2 years of age over-and-above that of brain ultrasound.

METHODS

We carried out a secondary analysis of data from extremely preterm infants collected for an RCT (SafeBoosC-II). Two hours of single-channel cross-brain EEG was used to analyse burst sharpness with an automated algorithm. The co-primary outcomes were moderate-or-severe NDI and MDI. Complete data were available from 58 infants. A predefined statistical analysis was adjusted for GA, sex and no, mild-moderate, and severe brain injury as detected by cranial ultrasound.

RESULTS

Nine infants had moderate-or-severe NDI and the mean MDI was 87 ± 17.3 SD. The typical burst sharpness was low (negative values) and varied relatively little (mean -0.81 ± 0.11 SD), but the odds ratio for NDI was increased by 3.8 (p = 0.008) and the MDI was reduced by -3.2 points (p = 0.14) per 0.1 burst sharpness units increase (+1 SD) in the adjusted analysis.

CONCLUSION

This study confirms the association between EEG-burst measures in preterm infants and neurodevelopment in childhood. Importantly, this was by a priori defined analysis.

IMPACT

A fully automated, computational measure of EEG in the first week of life was predictive of neurodevelopmental impairment at 2 years of age. This confirms many previous studies using expert reading of EEG. Only single-channel EEG data were used, adding to the applicability. EEG was recorded by several different devices thus this measure appears to be robust to differences in electrodes, amplifiers and filters. The likelihood ratio of a positive EEG test, however, was only about 2, suggesting little immediate clinical value.

Cross-sectional association between red blood cell distribution width and regional cerebral tissue oxygen saturation in preterm infants in the first 14 days after birth

Background

Hypoxia can threaten the metabolic functions of different systems in immature neonates, particularly the central nervous system. The red blood cell distribution width (RDW) has recently been reported as a prognostic factor in neurologic diseases. Herein, we examined the correlation between RDW and regional cerebral tissue oxygen saturation (rcSO2).

Methods

This cross-sectional study included 110 preterm infants born at a gestational age (GA) of <32 weeks, or with a birth weight (BW) of <1,500 g at our institution between January and June 2,022. The rcSO2 was monitored using near-infrared spectroscopy, and RDW was extracted from the complete blood count during the first 14 days after birth. RDW and rcSO2 measurements were analyzed using a cross-sectional research method.

Results

We divided the study population into two groups, with a mean rcSO2 value over the first 14 days. Fifty-three preterm had rcSO2 ≥ 55% and 57% < 55%. The 14-days-mean in the study population showing an association of lower rcSO2 values with higher RDW values. Significantly higher RDW values were observed in the low rcSO2 group compared with those in the high rcSO2 group. Threshold effect analysis showed that rcSO2 decreased with RDW values ≥18% (β, -0.03; 95% CI, -0.04 and -0.02; p ≥ 0.0001). After adjusting for potential confounders, an RDW of ≥18% was determined as the predictive cutoff value for preterm infants with low rcSO2 (Model I: OR, 3.31; 95% CI, 1.36-8.06; p = 0.009; and Model II: OR, 3.31; 95% CI, 1.28-8.53; p = 0.013).

Conclusions

An RDW of ≥18% in the first 14 days is associated with rcSO2 of <55% in preterm infants.

Cerebral oxygenation immediately after birth and long-term outcome in preterm neonates-a retrospective analysis

BACKGROUND

Prematurity is associated with increased risk for morbidity and mortality. Aim of this study was to evaluate whether cerebral oxygenation during fetal-to-neonatal transition period was associated with long-term outcome in very preterm neonates.

METHODS

Preterm neonates ≤ 32 weeks of gestation and/or ≤ 1500 g with measurements of cerebral regional oxygen saturation (crSO₂) and cerebral fractional tissue oxygen extraction (cFTOE) within the first 15 min after birth were analysed retrospectively. Arterial oxygen saturation (SpO₂) and heart rate (HR) were measured with pulse oximetry. Long-term outcome was assessed at two years using "Bayley Scales of Infant Development" (BSID-II/III). Included preterm neonates were stratified into two groups: adverse outcome group (BSID-III ≤ 70 or testing not possible due to severe cognitive impairment or mortality) or favorable outcome group (BSID-III > 70). As the association between gestational age and long-term outcome is well known, correction for gestational age might disguise the potential association between crSO₂ and neurodevelopmental impairment. Therefore, due to an explorative approach the two groups were compared without correction for gestational age.

RESULTS

Forty-two preterm neonates were included: adverse outcome group n = 13; favorable outcome group n = 29. Median(IQR) gestational age and birth weight were 24.8 weeks (24.2-29.8) and 760 g (670-1054) in adverse outcome group and 30.6 weeks (28.1-32.0) (p = 0.009*) and 1250 g (972-1390) (p = 0.001*) in the favorable outcome group, respectively. crSO₂ was lower (significant in 10 out of 14 min) and cFTOE higher in adverse outcome group. There were no difference in SpO₂, HR and fraction of inspired oxygen (FiO₂), except for FiO₂ in minute 11, with higher FiO₂ in the adverse outcome group.

CONCLUSION

Preterm neonates with adverse outcome had beside lower gestational age also a lower crSO₂ during immediate fetal-to-neonatal transition when compared to preterm neonates with age appropriate outcome. Lower gestational age in the adverse outcome group would suggest beside lower crSO₂ also lower SpO₂ and HR in this group, which were however similar in both groups.

Neuromonitoring in neonatal critical care part II: extremely premature infants and critically ill neonates

Neonatal intensive care has expanded from cardiorespiratory care to a holistic approach emphasizing brain health. To best understand and monitor brain function and physiology in the neonatal intensive care unit (NICU), the most commonly used tools are amplitude-integrated EEG, full multichannel continuous EEG, and near-infrared spectroscopy. Each of these modalities has unique characteristics and functions. While some of these tools have been the subject of expert consensus statements or guidelines, there is no overarching agreement on the optimal approach to neuromonitoring in the NICU. This work reviews current evidence to assist decision making for the best utilization of these neuromonitoring tools to promote neuroprotective care in extremely premature infants and in critically ill neonates. Neuromonitoring approaches in neonatal encephalopathy and neonates with possible seizures are discussed separately in the companion paper. IMPACT: For extremely premature infants, NIRS monitoring has a potential role in individualized brain-oriented care, and selective use of aEEG and cEEG can assist in seizure detection and prognostication. For critically ill neonates, NIRS can monitor cerebral perfusion, oxygen delivery, and extraction associated with disease processes as well as respiratory and hypodynamic management. Selective use of aEEG and cEEG is important in those with a high risk of seizures and brain injury. Continuous multimodal monitoring as well as monitoring of sleep, sleep-wake cycling, and autonomic nervous system have a promising role in neonatal neurocritical care.

Near-infrared spectroscopy in the medical management of infants

Near-infrared spectroscopy (NIRS) is a technology that is easy to use and can provide helpful information about organ oxygenation and perfusion by measuring regional tissue oxygen saturation (rSO2) with near-infrared light. The sensors can be placed in different anatomical locations to monitor rSO2 levels in several organs. While NIRS is not without limitations, this equipment is now becoming increasingly integrated into modern healthcare practice with the goal of achieving better outcomes for patients. It can be particularly applicable in the monitoring of pediatric patients because of their size, and especially so in infant patients. Infants are ideal for NIRS monitoring as nearly all of their vital organs lie near the skin surface which near-infrared light penetrates through. In addition, infants are a difficult population to evaluate with traditional invasive monitoring techniques that normally rely on the use of larger catheters and maintaining vascular access. Pediatric clinicians can observe rSO2 values in order to gain insight about tissue perfusion, oxygenation, and the metabolic status of their patients. In this way, NIRS can be used in a non-invasive manner to either continuously or periodically check rSO2. Because of these attributes and capabilities, NIRS can be used in various pediatric inpatient settings and on a variety of patients who require monitoring. The primary objective of this review is to provide pediatric clinicians with a general understanding of how NIRS works, to discuss how it currently is being studied and employed, and how NIRS could be increasingly used in the near future, all with a focus on infant management.

Association of early cerebral oxygen saturation and brain injury in extremely preterm infants

OBJECTIVE

To assess the association between cerebral saturation (crSO2) using Near-Infrared Spectroscopy (NIRS) and brain injury in extremely preterm infants.

STUDY DESIGN

This retrospective study includes 62 infants (<28 weeks gestation) who underwent continuous NIRS monitoring in the first 5 days after birth. Median crSO2 were compared in 12 h increments between infants with and without germinal matrix/intraventricular hemorrhage (GM/IVH). crSO2 was also compared by IVH severity, onset, and by grade of injury on term equivalent MRI.

RESULTS

After 48 h of life (HOL), infants with GM/IVH had significantly lower crSO2 than those without GM/IVH in analysis adjusted for potential confounding e.g., at 49-60 HOL (69.5 (66.2, 72.8) vs. 74.7 (71.8, 77.6), p = 0.023). There were no significant differences in crSO2 by IVH subcategory or injury severity on MRI.

CONCLUSION

Clinical use of NIRS has the potential to identify crSO2 patterns associated with development of GM/IVH.

Prevention of severe brain injury in very preterm neonates: A quality improvement initiative

OBJECTIVE

To determine the impact of neuroprotection interventions bundle on the incidence of severe brain injury or early death (intraventricular hemorrhage grade 3/4 or death by 7 days or ventriculomegaly or cystic periventricular leukomalacia on 1-month head ultrasound, primary composite outcome) in very preterm (27^0/7 to ≤ 29^6/7 weeks gestational age) infants.

STUDY DESIGN

Prospective quality improvement initiative, from April 2017-September 2019, with neuroprotection interventions bundle including cerebral NIRS, TcCO₂, and HeRO monitoring-based management algorithm, indomethacin prophylaxis, protocolized bicarbonate and inotropes use, noise reduction, and neutral positioning.

RESULT

There was a decrease in the incidence of the primary composite outcome in the intervention period on unadjusted (N = 11/99, pre-intervention to N = 0/127, intervention period, p < 0.001) and adjusted analysis (adjusted for birthweight and Apgar score <5 at 5 min, aOR = 0.042, 95% CI = 0.003-0.670, p = 0.024).

CONCLUSIONS

Neuroprotection interventions bundle was associated with significant decrease in severe brain injury or early death in very preterm infants.

Pathogenesis and prevention of intraventricular hemorrhage

Despite improvements in the mortality rates of preterm infants, rates of germinal matrix intraventricular hemorrhage (IVH) have remained static with an overall incidence of 25% in infants less than 32 weeks. The importance of the lesion relates primarily to the underlying injury to the developing brain and the associated long-term neurodevelopmental consequences. This clinical-orientated review focuses on the pathogenesis of IVH and discusses the evidence behind proposed prevention strategies.

Multi-laboratory performance assessment of diffuse optics instruments: the BitMap exercise

SIGNIFICANCE

Multi-laboratory initiatives are essential in performance assessment and standardization-crucial for bringing biophotonics to mature clinical use-to establish protocols and develop reference tissue phantoms that all will allow universal instrument comparison.

AIM

The largest multi-laboratory comparison of performance assessment in near-infrared diffuse optics is presented, involving 28 instruments and 12 institutions on a total of eight experiments based on three consolidated protocols (BIP, MEDPHOT, and NEUROPT) as implemented on three kits of tissue phantoms. A total of 20 synthetic indicators were extracted from the dataset, some of them defined here anew.

APPROACH

The exercise stems from the Innovative Training Network BitMap funded by the European Commission and expanded to include other European laboratories. A large variety of diffuse optics instruments were considered, based on different approaches (time domain/frequency domain/continuous wave), at various stages of maturity and designed for different applications (e.g., oximetry, spectroscopy, and imaging).

RESULTS

This study highlights a substantial difference in hardware performances (e.g., nine decades in responsivity, four decades in dark count rate, and one decade in temporal resolution). Agreement in the estimates of homogeneous optical properties was within 12% of the median value for half of the systems, with a temporal stability of <5  %   over 1 h, and day-to-day reproducibility of <3  %  . Other tests encompassed linearity, crosstalk, uncertainty, and detection of optical inhomogeneities.

CONCLUSIONS

This extensive multi-laboratory exercise provides a detailed assessment of near-infrared Diffuse optical instruments and can be used for reference grading. The dataset-available soon in an open data repository-can be evaluated in multiple ways, for instance, to compare different analysis tools or study the impact of hardware implementations.

Multimodal Neurologic Monitoring in Children With Acute Brain Injury

Children with acute neurologic illness are at high risk of mortality and long-term neurologic disability. Severe traumatic brain injury, cardiac arrest, stroke, and central nervous system infection are often complicated by cerebral hypoxia, hypoperfusion, and edema, leading to secondary neurologic injury and worse outcome. Owing to the paucity of targeted neuroprotective therapies for these conditions, management emphasizes close physiologic monitoring and supportive care. In this review, we will discuss advanced neurologic monitoring strategies in pediatric acute neurologic illness, emphasizing the physiologic concepts underlying each tool. We will also highlight recent innovations including novel monitoring modalities, and the application of neurologic monitoring in critically ill patients at risk of developing neurologic sequelae.

Early cerebral hypoxia in extremely preterm infants and neurodevelopmental impairment at 2 year of age: A post hoc analysis of the SafeBoosC II trial

BACKGROUND

The SafeBoosC II, randomised clinical trial, showed that the burden of cerebral hypoxia was reduced with the combination of near infrared spectroscopy and a treatment guideline in extremely preterm infants during the first 72 hours after birth. We have previously reported that a high burden of cerebral hypoxia was associated with cerebral haemorrhage and EEG suppression towards the end of the 72-hour intervention period, regardless of allocation. In this study we describe the associations between the burden of cerebral hypoxia and the 2-year outcome.

METHODS

Cerebral oxygenation was continuously monitored from 3 to 72 hours after birth in 166 extremely preterm infants. At 2 years of age 114 of 133 surviving children participated in the follow-up program: medical examination, Bayley II or III test and the parental Ages and Stages Questionnaire. The infants were classified according to the burden of hypoxia: within the first three quartiles (n = 86, low burden) or within in the 4th quartile (n = 28, high burden). All analyses were conducted post hoc.

RESULTS

There were no statistically significant differences between the quantitative assessments of neurodevelopment in the groups of infants with the low burden of cerebral hypoxia versus the group of infants with the high burden of cerebral hypoxia. The infants in the high hypoxia burden group had a higher-though again not statistically significant-rate of cerebral palsy (OR 2.14 (0.33-13.78)) and severe developmental impairment (OR 4.74 (0.74-30.49).

CONCLUSIONS

The burden of cerebral hypoxia was not significantly associated with impaired 2-year neurodevelopmental outcome in this post-hoc analysis of a feasibility trial.

Three Physiological Components That Influence Regional Cerebral Tissue Oxygen Saturation

Near-infrared spectroscopy (NIRS) measurement of regional cerebral tissue oxygen saturation (rcStO2) has become a topic of high interest in neonatology. Multiple studies have demonstrated that rcStO2 measurements are feasible in the delivery room during immediate transition and resuscitation as well as after admission to the neonatal intensive care unit. Reference ranges for different gestational ages, modes of delivery, and devices have already been published. RcStO2 reflects a mixed tissue saturation, composed of arterial (A), venous (V), and capillary signals, derived from small vessels within the measurement compartment. The A:V signal ratio fluctuates based on changes in oxygen delivery and oxygen consumption, which enables a reliable trend monitoring of the balance between these two parameters. While the increasing research evidence supports its use, the interpretation of the absolute values of and trends in rcStO2 is still challenging, which halts its routine use in the delivery room and at the bedside. To visualize the influencing factors and improve the understanding of rcStO2 values, we have created a flowchart, which focuses on the three major physiological components that affect rcStO2: oxygen content, circulation, and oxygen extraction. Each of these has its defining parameters, which are discussed in detail in each section.

The Effect of Antenatal Neuroprotective Magnesium Sulfate Treatment on Cerebral Oxygenation in Preterm Infants

OBJECTIVE

Antenatal magnesium sulfate (MgSO₄) treatment is associated with reduced risk of cerebral palsy in preterm infants. We aimed to investigate whether this treatment leads to any alterations on cerebral hemodynamics which could be detected by near-infrared spectroscopy (NIRS) readings in early postnatal life.

STUDY DESIGN

Infants with gestational ages (GAs) ≤ 32 weeks were divided into two groups regarding their exposure to antenatal neuroprotective MgSO₄ treatment or not. NIRS monitoring was performed to all infants, and readings were recorded for 2 hours each day during the first 3 days of life. The primary aim was to compare regional cerebral oxygen saturation (rcSO₂) and cerebral fractional tissue oxygen extraction (cFTOE) between the groups.

RESULTS

Sixty-six infants were exposed to antenatal MgSO₄, while 64 of them did not. GA and birth weight were significantly lower in the treatment group (p < 0.01). No difference was observed in rcSO₂ and cFTOE levels in the first, second, and the third days of life (p > 0.05). An insignificant reduction in severe intraventricular hemorrhage rates was observed (8 vs. 15%, p = 0.24).

CONCLUSION

We could not demonstrate any effect on cerebral oxygenation of preterm infants in early postnatal life that could be attributed to antenatal neuroprotective MgSO₄ treatment. Future studies are warranted to clarify the exact underlying mechanisms of neuroprotection.

Pilot study of cerebral and somatic autoregulation using NIRS in preterm neonates

BACKGROUND

As neonates transition from a relatively hypoxic environment to extra-uterine life, arterial oxygen saturation dramatically increases. This transition occurs while most organs have not fully matured. The ability for immature tissue to adequately extract and utilize oxygen remains largely unknown. With the development of near-infrared spectroscopy (NIRS), measuring specific tissue oxygen saturation (StO2) noninvasively, clinicians can measure StO2 and determine if adequate tissue oxygenation is maintained. The objective of this study is to determine the relationships of NIRS brain and somatic autoregulation function to patients' severity of illness.

METHODS

In this prospective cohort pilot study, after parental consent, neonates less than 34 weeks with arterial access, were enrolled. The FORE-SIGHT NIRS probe was placed on the forehead and abdominal wall for 24 hours. Continuous arterial blood pressure, SpO2 and cerebral and somatic NIRS were used to derive autoregulation function.

RESULTS

Data was obtained from 17 neonates (0.540 to 2.37 kg, gestation 23.0 to 33.2 weeks). The autoregulation function categorizes pressure passive index (PPI) values as good, borderline, or poor. For normal autoregulation function, PPI values tend to be low and fairly constant for a range of MAP. The PPI borderline zone is a hypothetical range of PPI values where autoregulation function transitions from good to poor.

CONCLUSION

Our results show most premature neonates, as long as they maintained normal BP and systemic circulation can autoregulate cerebral perfusion. When BP are above or below the normal MAP for age, the neonate is at risk for losing brain and somatic autoregulation.

Cerebral Blood Flow Monitoring in High-Risk Fetal and Neonatal Populations

Cerebrovascular pressure autoregulation promotes stable cerebral blood flow (CBF) across a range of arterial blood pressures. Cerebral autoregulation (CA) is a developmental process that reaches maturity around term gestation and can be monitored prenatally with both Doppler ultrasound and magnetic resonance imaging (MRI) techniques. Postnatally, there are key advantages and limitations to assessing CA with Doppler ultrasound, MRI, and near-infrared spectroscopy. Here we review these CBF monitoring techniques as well as their application to both fetal and neonatal populations at risk of perturbations in CBF. Specifically, we discuss CBF monitoring in fetuses with intrauterine growth restriction, anemia, congenital heart disease, neonates born preterm and those with hypoxic-ischemic encephalopathy. We conclude the review with insights into the future directions in this field with an emphasis on collaborative science and precision medicine approaches.

Fetal Hemoglobin and Tissue Oxygenation Measured With Near-Infrared Spectroscopy-A Systematic Qualitative Review

Fetal hemoglobin (HbF) is a principal oxygen carrier in the blood of preterm and term neonates. Compared to adult hemoglobin, it has a significantly higher affinity for oxygen and its oxyhemoglobin dissociation curve (ODC) is left-shifted accordingly. Tissue oxygenation measured with near-infrared spectroscopy (NIRS) during neonatal intensive care is directly affected by hemoglobin concentration. We performed a systematic qualitative review regarding the impact of HbF on tissue oxygenation monitoring by NIRS. The PubMed/Medline, EMBASE, Cochrane library and CINAHL databases were searched from inception to May 2021 for studies relating to HbF and NIRS in preterm and term neonates in the first days and weeks after birth. Out of 1,429 eligible records, four observational studies were included. Three studies found no effect of HbF on cerebral tissue oxygenation. One peripheral NIRS study found a positive correlation between HbF and peripheral fractional oxygen extraction (FOE). Currently available limited data suggest that FHbF could affect peripheral muscle FOE, but seems not to affect cerebral oxygenation in preterm neonates. More studies are needed to draw a final conclusion on this matter, especially concerning the oxygenation changes driven by adult RBC transfusions.

Applications of functional near-infrared spectroscopy (fNIRS) in neonates

Functional near-infrared spectroscopy (fNIRS) is a method of monitoring brain oxygenation. This technique investigates hemodynamic changes in the cerebral cortex. fNIRS is widely used in clinical and scientific research. In this review, we focus on the applications of fNIRS on neonates. Here, applications form two distinct categories: task associated studies, and hemoglobin phase change studies. fNIRS is non-invasive, easily performed, and repeatable. However, it has limited monitoring depth and spatial resolution when used in newborns. Moreover, with recent technological advances, it is now possible to explore neuronal activity patterns using fNIRS in both healthy and pathological conditions. For more than 20 years, fNIRS has enabled clinicians to gain insight into cerebral development and mechanisms of injury in neonates. fNIRS is a useful supplement to existing technologies due to its ability to interrogate the neonatal brain function.

Construction and validation of a database of head models for functional imaging of the neonatal brain

The neonatal brain undergoes dramatic structural and functional changes over the last trimester of gestation. The accuracy of source localisation of brain activity recorded from the scalp therefore relies on accurate age-specific head models. Although an age-appropriate population-level atlas could be used, detail is lost in the construction of such atlases, in particular with regard to the smoothing of the cortical surface, and so such a model is not representative of anatomy at an individual level. In this work, we describe the construction of a database of individual structural priors of the neonatal head using 215 individual-level datasets at ages 29-44 weeks postmenstrual age from the Developing Human Connectome Project. We have validated a method to segment the extra-cerebral tissue against manual segmentation. We have also conducted a leave-one-out analysis to quantify the expected spatial error incurred with regard to localising functional activation when using a best-matching individual from the database in place of a subject-specific model; the median error was calculated to be 8.3 mm (median absolute deviation 3.8 mm). The database can be applied for any functional neuroimaging modality which requires structural data whereby the physical parameters associated with that modality vary with tissue type and is freely available at www.ucl.ac.uk/dot-hub.

Intervention and Outcome for Neonatal Hypotension

Many observational studies have shown that infants with blood pressures (BPs) that are in the lower range for their gestational age tend to have increased complications such as an increased rate of significant intraventricular hemorrhage and adverse long-term outcome. This relationship does not prove causation nor should it create an indication for treatment. However, many continue to intervene with medication for low BP on the assumption that an increase in BP will result in improved outcome. Only adequately powered prospective randomized controlled trials can answer the question of whether individual treatments of low BP are beneficial.

The Various Oximetric Techniques Used for the Evaluation of Blood Oxygenation

Adequate oxygen delivery to a tissue depends on sufficient oxygen content in arterial blood and blood flow to the tissue. Oximetry is a technique for the assessment of blood oxygenation by measurements of light transmission through the blood, which is based on the different absorption spectra of oxygenated and deoxygenated hemoglobin. Oxygen saturation in arterial blood provides information on the adequacy of respiration and is routinely measured in clinical settings, utilizing pulse oximetry. Oxygen saturation, in venous blood (SvO₂) and in the entire blood in a tissue (StO₂), is related to the blood supply to the tissue, and several oximetric techniques have been developed for their assessment. SvO₂ can be measured non-invasively in the fingers, making use of modified pulse oximetry, and in the retina, using the modified Beer–Lambert Law. StO₂ is measured in peripheral muscle and cerebral tissue by means of various modes of near infrared spectroscopy (NIRS), utilizing the relative transparency of infrared light in muscle and cerebral tissue. The primary problem of oximetry is the discrimination between absorption by hemoglobin and scattering by tissue elements in the attenuation measurement, and the various techniques developed for isolating the absorption effect are presented in the current review, with their limitations.

Burden of hypoxia and intraventricular haemorrhage in extremely preterm infants

OBJECTIVE

Thresholds of cerebral hypoxia through monitoring of near-infrared spectroscopy tissue oxygenation index (TOI) were used to investigate the relationship between intraventricular haemorrhage (IVH) and indices of hypoxia.

DESIGN

Prospective observational study.

SETTING

A single-centre neonatal intensive care unit.

PATIENTS

Infants <28 weeks' gestation with an umbilical artery catheter.

METHODS

Thresholds of hypoxia were determined from mean values of TOI using sequential Χ² tests and used alongside thresholds from existing literature to calculate percentage of time in hypoxia and burden of hypoxia below each threshold. These indices were then compared between IVH groups.

RESULTS

44 infants were studied for a median of 18.5 (range 6-21) hours in the first 24 hours of life. Sequential Χ² analysis yielded a TOI threshold of 71% to differentiate between IVH (16 infants) and no IVH (28 infants). Percentage of time in hypoxia was significantly higher in infants with IVH than those without, using thresholds of 60%-67%. Burden of hypoxia was significantly higher in infants with IVH than without, using thresholds of 62%-80%. With the threshold of 71%, percentage of time in hypoxia was lower by 12.2% with a 95% CI of (-25.7 to 1.2) (p=0.073), and the burden of hypoxia was lower by 29.2% hour (%h) (95% CI -55.2 to -3.1)%h (p=0.012) in infants without IVH than those with IVH.

CONCLUSIONS

Using defined TOI thresholds, infants with IVH spent higher percentage of time in hypoxia with higher burden of cerebral hypoxia than those without, in the first 24 hours of life.

Resting-State NIRS-EEG in Unresponsive Patients with Acute Brain Injury: A Proof-of-Concept Study

BACKGROUND

Neurovascular-based imaging techniques such as functional MRI (fMRI) may reveal signs of consciousness in clinically unresponsive patients but are often subject to logistical challenges in the intensive care unit (ICU). Near-infrared spectroscopy (NIRS) is another neurovascular imaging technique but low cost, can be performed serially at the bedside, and may be combined with electroencephalography (EEG), which are important advantages compared to fMRI. Combined NIRS-EEG, however, has never been evaluated for the assessment of neurovascular coupling and consciousness in acute brain injury.

METHODS

We explored resting-state oscillations in eight-channel NIRS oxyhemoglobin and eight-channel EEG band-power signals to assess neurovascular coupling, the prerequisite for neurovascular-based imaging detection of consciousness, in patients with acute brain injury in the ICU (n = 9). Conscious neurological patients from step-down units and wards served as controls (n = 14). Unsupervised adaptive mixture-independent component analysis (AMICA) was used to correlate NIRS-EEG data with levels of consciousness and clinical outcome.

RESULTS

Neurovascular coupling between NIRS oxyhemoglobin (0.07-0.13 Hz) and EEG band-power (1-12 Hz) signals at frontal areas was sensitive and prognostic to changing consciousness levels. AMICA revealed a mixture of five models from EEG data, with the relative probabilities of these models reflecting levels of consciousness over multiple days, although the accuracy was less than 85%. However, when combined with two channels of bilateral frontal neurovascular coupling, weighted k-nearest neighbor classification of AMICA probabilities distinguished unresponsive patients from conscious controls with > 90% accuracy (positive predictive value 93%, false discovery rate 7%) and, additionally, identified patients who subsequently failed to recover consciousness with > 99% accuracy.

DISCUSSION

We suggest that NIRS-EEG for monitoring of acute brain injury in the ICU is worthy of further exploration. Normalization of neurovascular coupling may herald recovery of consciousness after acute brain injury.

Defining the reference range of regional cerebral tissue oxygen saturation using a new portable near-infrared spectroscopy device for term infants

BACKGROUND

The arterial oxygen saturation of infants requiring resuscitation can be monitored using a pulse oximeter. However, the device cannot provide information about cerebral oxygenation. Thus, we used a new portable near-infrared spectroscopy (NIRS) device that can monitor regional cerebral tissue oxygen saturation (crSO₂) with a probe attached to the examiner's finger.

AIM

To identify the reference ranges for crSO₂ within the first 10 min after birth in term infants who did not receive any medical intervention in the delivery room.

RESULTS

crSO₂ in the left frontoparietal area of the forebrain was measured within the first 10 min of life in 127 healthy term infants. The median gestational age and birth weight were 37.6 weeks and 2742 g, respectively, and 85% of the infants were delivered via a scheduled cesarean section. The 3rd-97th percentile values for crSO₂ ranged from 33.1% to 56.7% at 1 min, from 33.2% to 59.5% at 2 min, and from 38.7% to 66.6% at 5 min after birth. A median of 3.5 min was required to achieve a crSO₂ > 50%.

CONCLUSIONS

This study showed the reference ranges for crSO₂ measured with the new portable NIRS device within the first 10 min after birth in term infants.

Combined Multimodal Cerebral Monitoring and Focused Hemodynamic Assessment in the First 72 h in Extremely Low Gestational Age Infants

BACKGROUND

Characteristic changes in cerebral saturation (CrSO2), amplitude-integrated electroencephalography (aEEG), and echocardiography (ECHO) may be associated with intraventricular hemorrhage (IVH); however, the feasibility of their combined application is not known.

OBJECTIVE

The aim of this work was to investigate the feasibility and safety of combined multimodal cerebral and hemodynamic monitoring in extremely low gestational age (ELGA) infants in the first 72 h after birth.

METHODS

In this prospective -observational study of 50 infants born between 23 + 0 and 27 + 6 weeks gestation, we measured CrSO2 and aEEG, starting <8 h until 72 h of age. Sequential echocardiography and head ultrasound were performed at 4-8, 12-18, 24-30, and 48-60 h of age. The primary outcome was feasibility of multimodal monitoring, defined as >75% of the subjects satisfying at least 3/4 criteria: (a) CrSO2 and (b) aEEG monitoring each for >75% of the time, and (c) at least 2 out of 4 ECHO and (d) head ultrasounds (at least one by age 24 h). Adverse reactions to sensors, desaturation, and bradycardia during ultrasound studies were recorded.

RESULTS

Fifty infants were enrolled over 14 months. Multimodal monitoring was feasible in 49 (98%) infants. Forty-one (82%) infants fulfilled all 4 criteria. Mild erythema below CrSO2 sensors lasting 3-8 h without skin breakdown was noted in 8/50 subjects (16%). Desaturation was noted during 17/197 (8.6%) of the ultrasound studies. In total, 26/50 (52%) infants developed IVH (grade I/II, n = 22; grade III/IV, n = 4).

CONCLUSION

Multimodal monitoring is feasible, safe, and well tolerated in ELGA infants in the first 72 h after birth.

A practical approach to cerebral near-infrared spectroscopy (NIRS) directed hemodynamic management in noncardiac pediatric anesthesia

Safeguarding cerebral function is of major importance during pediatric anesthesia. Premature, ex-premature, and full-term neonates can be vulnerable to physiological changes that occur during anesthesia and surgery. Data from studies performed during pediatric cardiac surgery and in neonatal/pediatric intensive care units have shown the benefits of near-infrared spectroscopy (NIRS) monitoring of regional cerebral oxygenation (c-rSO₂ ). However, NIRS monitoring is seldom used during noncardiac pediatric anesthesia. Despite compelling evidence that blood pressure does not reflect end-organ perfusion, it is still regarded as the most important determinant of cerebral perfusion and the most relevant hemodynamic management target parameter by most (pediatric) anesthetists. The principle of NIRS monitoring is not self-explanatory and sometimes seems even counterintuitive, which may explain why many anesthesiologists are reserved regarding its use. The first part of this paper is dedicated to a clinical introduction to NIRS monitoring. Despite scientific efforts, it has not yet been possible to define individual lower limit c-rSO₂ values and it is unlikely this will succeed in the near future. Nonetheless, published treatment algorithms usually specify c-rSO₂ values which may be associated with cerebral hypoxia. Our treatment guideline for maintaining sufficient cerebral oxygenation differs fundamentally from all previously published approaches. We define a baseline c-rSO₂ value, registered in the awake child prior to anesthesia induction, as the lowest acceptable limit during anesthesia and surgery. The cerebral rSO₂ is the single target parameter, while blood pressure, heart rate, P_a CO₂ , and SaO₂ are major parameters that determine the c-rSO2. Cerebral NIRS monitoring, interpreted together with its continuously available contributing parameters, may help avoid potentially harmful episodes of cerebral desaturation in anesthetized pediatric patients.

Regional tissue oxygenation monitoring in the neonatal intensive care unit: evidence for clinical strategies and future directions

Near-infrared spectroscopy (NIRS)-based monitoring of regional tissue oxygenation (rSO₂) is becoming more commonplace in the neonatal intensive care unit (NICU). While increasing evidence supports rSO₂ monitoring, actual standards for applying this noninvasive bedside technique continue to evolve. This review highlights the current strengths and pitfalls surrounding practical NIRS-based monitoring in the neonatal population. The physiologic background of rSO₂ monitoring is discussed, with attention to understanding oxygen delivery/consumption mismatch and its effects on tissue oxygen extraction. The bedside utility of both cerebral and peripheral rSO₂ monitoring in the NICU is then explored from two perspectives: (1) disease/event-specific "responsive" monitoring and (2) "routine," continuous monitoring. Recent evidence incorporating both monitoring approaches is summarized with emphasis on practical applicability in the NICU. Finally, a future paradigm for a broad-based NIRS monitoring strategy is presented, with attention towards improving personalization of neonatal care and ultimately enhancing long-term outcomes.

Cerebral perfusion and assessing hemodynamic significance for patent ductus arteriosus using near infrared red spectroscopy in very low birth weight infants

INTRODUCTION/OBJECTIVE

To study the impact of hemodynamically significant patent ductus arteriosus (hsPDA), using near infrared red spectroscopy (NIRS) regional cerebral (SrO₂), renal (RrO₂) saturation measurements, and fractional tissue oxygenation extraction (FTOE) before and after medical and/or surgical treatment.

METHODS

Prospective cohort study of very low birth weight (VLBW) preterm infants with hsPDA requiring treatment from March 2014 to December 2016 in a tertiary Neonatal Intensive Care Unit in Singapore. NIRS was applied at diagnosis until 24-48 h after the last dose of ibuprofen or postsurgical ligation. All PDAs were documented to be closed by echocardiography. Post-treatment values (control group) were compared against pretreatment values.

RESULTS

Twenty-nine infants were studied, with mean gestational age of 26.7 weeks and birth weight of 956 g. Median day of life of PDA diagnosis was 4. Seven infants (24.1%) underwent PDA ligation. There was significant reduction in FTOE before treatment till after last dose of medication or ligation by a mean difference of 7.27% (p < .05). Reduction in FTOE was also found between the first dose of medication till after the last dose or ligation. Cerebral SrO₂ significantly increased between first dose of medication till last dose of medication by a mean difference of 3.09% (p = .034). RrSO2 values were not significantly affected. No correlation between NIRS values and PDA size was found.

CONCLUSIONS

Significant increase in cerebral SrO₂ and reduction in FTOE by NIRS post PDA closure in hemodynamically significant PDAs suggest that PDA closure may reduce cerebral hypoxia burden.

No neurodevelopmental benefit of cerebral oximetry in the first randomised trial (SafeBoosC II) in preterm infants during the first days of life

AIM

Cerebral hypoxia has been associated with neurodevelopmental impairment. We studied whether reducing cerebral hypoxia in extremely preterm infants during the first 72 hours of life affected neurological outcomes at two years of corrected age.

METHODS

In 2012-2013, the phase II randomised Safeguarding the Brains of our smallest Children trial compared visible cerebral near-infrared spectroscopy (NIRS) monitoring in an intervention group and blinded NIRS monitoring in a control group. Cerebral hypoxia was significantly reduced in the intervention group. We followed up 115 survivors from eight European centres at two years of corrected age, by conducting a medical examination and assessing their neurodevelopment with the Bayley Scales of Infant and Toddler Development, Second or Third Edition, and the parental Ages and Stages Questionnaire (ASQ).

RESULTS

There were no differences between the intervention (n = 65) and control (n = 50) groups with regard to the mean mental developmental index (89.6 ± 19.5 versus 88.4 ± 14.7, p = 0.77), ASQ score (215 ± 58 versus 213 ± 58, p = 0.88) and the number of children with moderate-to-severe neurodevelopmental impairment (10 versus six, p = 0.58).

CONCLUSION

Cerebral NIRS monitoring was not associated with long-term benefits or harm with regard to neurodevelopmental outcome at two years of corrected age.

Interpretation of Cerebral Oxygenation Changes in the Preterm Infant

Near-infrared spectroscopy (NIRS) allows for continuous, non-invasive monitoring of end-organ tissue oxygenation. The use of NIRS, cerebral NIRS (cNIRS) in particular, in neonatal care has increased significantly over the last few years. This dynamic monitoring technique provides real-time information on the cerebral and haemodynamic status of the neonate and has the potential to serve as an important adjunct to patient care with some centres routinely utilising cNIRS to aid decision-making at the bedside. cNIRS values may be influenced by many variables, including cardiac, respiratory and metabolic parameters, and therefore it is essential to understand the pathophysiology behind alterations in cNIRS values. Correct interpretation is required to direct appropriate patient-specific interventions. This article aims to assist clinicians in deciphering cNIRS values by providing an overview of potential causes of fluctuations in cNIRS values, illustrated by common clinical scenarios, with particular emphasis on the preterm infant.

Noninvasive hemodynamic monitoring of septic shock in children

Septic shock in children is associated with high mortality and morbidity. Its management is time-sensitive and must be aggressive and target oriented. The use of clinical assessment alone to differentiate between cold and warm shock and to select the appropriate inotropic and vasoactive medications is fraught with errors. Semi-quantitative and quantitative assessment of the preload, contractility and afterload using non-invasive tools has been suggested, in conjunction with clinical and laboratory assessment, to direct shock management and select between vasopressors, vasodilators and inotropes or a combination of these drugs. This review aims to describe non-invasive tools to assess the hemodynamic status in septic shock including echocardiography, trans-thoracic/trans-esophageal Doppler and electrical cardiometry. As septic shock is a dynamic condition that changes markedly overtime, frequent or continuous measurement of the cardiac output (CO), systemic vascular resistance (SVR) and other hemodynamic parameters using the above-mentioned tools is essential to personalize the treatment and adapt it over time. The different combinations of blood pressure, CO and SVR serve as a pathophysiological framework to manage fluid therapy and titrate inotropic and vasoactive drugs. Near infrared spectroscopy is introduced as a non-invasive method to measure end organ perfusion and assess the response to treatment.

Non-invasive imaging modalities to study neurodegenerative diseases of aging brain

The aim of this article is to highlight current approaches for imaging elderly brain, indispensable for cognitive neuroscience research with emphasis on the basic physical principles of various non-invasive neuroimaging techniques. The first part of this article presents a quick overview of the primary non-invasive neuroimaging modalities used by cognitive neuroscientists such as transcranial magnetic stimulation (TMS), transcranial electrical stimulation (tES), electroencephalography (EEG), magnetoencephalography (MEG), single photon emission computed tomography (SPECT), positron emission tomography (PET), magnetic resonance spectroscopic imaging (MRSI), Profusion imaging, functional magnetic resonance imaging (fMRI), near infrared spectroscopy (NIRS) and diffusion tensor imaging (DTI) along with tractography and connectomics. The second part provides a comprehensive overview of different multimodality imaging techniques for various cognitive neuroscience studies of aging brain.

An International, Multicenter, Observational Study of Cerebral Oxygenation during Infant and Neonatal Anesthesia

BACKGROUND

General anesthesia during infancy is associated with neurocognitive abnormalities. Potential mechanisms include anesthetic neurotoxicity, surgical disease, and cerebral hypoxia-ischemia. This study aimed to determine the incidence of low cerebral oxygenation and associated factors during general anesthesia in infants.

METHODS

This multicenter study enrolled 453 infants aged less than 6 months having general anesthesia for 30 min or more. Regional cerebral oxygenation was measured by near-infrared spectroscopy. We defined events (more than 3 min) for low cerebral oxygenation as mild (60 to 69% or 11 to 20% below baseline), moderate (50 to 59% or 21 to 30% below baseline), or severe (less than 50% or more than 30% below baseline); for low mean arterial pressure as mild (36 to 45 mmHg), moderate (26 to 35 mmHg), or severe (less than 25 mmHg); and low pulse oximetry saturation as mild (80 to 89%), moderate (70 to 79%), or severe (less than 70%).

RESULTS

The incidences of mild, moderate, and severe low cerebral oxygenation were 43%, 11%, and 2%, respectively; mild, moderate, and severe low mean arterial pressure were 62%, 36%, and 13%, respectively; and mild, moderate, and severe low arterial saturation were 15%, 4%, and 2%, respectively. Severe low oxygen saturation measured by pulse oximetry was associated with mild and moderate cerebral desaturation; American Society of Anesthesiology Physical Status III or IV versus I was associated with moderate cerebral desaturation. Severe low cerebral saturation events were too infrequent to analyze.

CONCLUSIONS

Mild and moderate low cerebral saturation occurred frequently, whereas severe low cerebral saturation was uncommon. Low mean arterial pressure was common and not well associated with low cerebral saturation. Unrecognized severe desaturation lasting 3 min or longer in infants seems unlikely to explain the subsequent development of neurocognitive abnormalities.

The role of near-infrared spectroscopy monitoring in preterm infants

Neurological morbidities such as peri/intraventricular hemorrhage and periventricular leukomalacia largely determine the neurodevelopmental outcome of vulnerable preterm infants and our aim should be to minimize their occurrence or severity. Bed-side neuromonitoring could provide valuable pieces of information about possible hemodynamic disturbances that are significantly associated with neurological morbidities and increased mortality. Near-infrared spectroscopy offers evaluation of regional cerebral oxygenation, which in conjunction with other non-invasive methods may give us a more complete picture about end-organ perfusion. This monitoring tool could help us fully understand the pathophysiology of severe neurological morbidities and guide our management in order to reduce their incidence.

Simultaneous functional near-infrared spectroscopy and electroencephalography for monitoring of human brain activity and oxygenation: a review

Multimodal monitoring has become particularly common in the study of human brain function. In this context, combined, synchronous measurements of functional near-infrared spectroscopy (fNIRS) and electroencephalography (EEG) are getting increased interest. Because of the absence of electro-optical interference, it is quite simple to integrate these two noninvasive recording procedures of brain activity. fNIRS and EEG are both scalp-located procedures. fNIRS estimates brain hemodynamic fluctuations relying on spectroscopic measurements, whereas EEG captures the macroscopic temporal dynamics of brain electrical activity through passive voltages evaluations. The "orthogonal" neurophysiological information provided by the two technologies and the increasing interest in the neurovascular coupling phenomenon further encourage their integration. This review provides, together with an introduction regarding the principles and future directions of the two technologies, an evaluation of major clinical and nonclinical applications of this flexible, low-cost combination of neuroimaging modalities. fNIRS-EEG systems exploit the ability of the two technologies to be conducted in an environment or experimental setting and/or on subjects that are generally not suited for other neuroimaging modalities, such as functional magnetic resonance imaging, positron emission tomography, and magnetoencephalography. fNIRS-EEG brain monitoring settles itself as a useful multimodal tool for brain electrical and hemodynamic activity investigation.

Cerebral near-infrared spectroscopy monitoring for prevention of brain injury in very preterm infants

BACKGROUND

Cerebral injury and long-term neurodevelopmental impairment is common in extremely preterm infants. Cerebral near-infrared spectroscopy (NIRS) enables continuous estimation of cerebral oxygenation. This diagnostic method coupled with appropriate interventions if NIRS is out of normal range (that is cerebral oxygenation within the 55% to 85% range) may offer benefits without causing more harms. Therefore, NIRS coupled with appropriate responses to abnormal findings on NIRS needs assessment in a systematic review of randomised clinical trials and quasi-randomised studies.

OBJECTIVES

To evaluate the benefits and harms of interventions that attempt to alter cerebral oxygenation guided by cerebral NIRS monitoring in order to prevent cerebral injury, improve neurological outcome, and increase survival in preterm infants born more than 8 weeks preterm.

SEARCH METHODS

We used the standard search strategy of the Cochrane Neonatal Review Group to search the Cochrane Central Register of Controlled Trials (CENTRAL 2016, Issue 8), MEDLINE via PubMed (1966 to 10 September 2016), Embase (1980 to 10 September 2016), and CINAHL (1982 to 10 September 2016). We also searched clinical trial databases, conference proceedings, and the reference lists of retrieved articles for randomised clinical trials and quasi-randomised studies.

SELECTION CRITERIA

Randomised clinical trials and quasi-randomised clinical studies comparing continuous cerebral NIRS monitoring for at least 24 hours versus blinded NIRS or versus no NIRS monitoring.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected, assessed the quality of, and extracted data from the included trials and studies. If necessary, we contacted authors for further information. We conducted assessments of risks of bias; risks of design errors; and controlled the risks of random errors with Trial Sequential Analysis. We assessed the quality of the evidence with GRADE.

MAIN RESULTS

One randomised clinical trial met inclusion criteria, including infants born more than 12 weeks preterm. The trial employed adequate methodologies and was assessed at low risk of bias. One hundred and sixty-six infants were randomised to start continuous cerebral NIRS monitoring less than 3 hours after birth until 72 hours after birth plus appropriate interventions if NIRS was out of normal range according to a guideline versus conventional monitoring with blinded NIRS. There was no effect of NIRS plus guideline of mortality until term-equivalent age (RR 0.50, 95% CI 0.29 to 1.00; one trial; 166 participants). There were no effects of NIRS plus guideline on intraventricular haemorrhages: all grades (RR 0.93, 95% CI 0.65 to 1.34; one trial; 166 participants); grade III/IV (RR 0.57, 95% CI 0.25 to 1.31; one trial; 166 participants); and cystic periventricular leukomalacia (which did not occur in either group). Likewise, there was no effect of NIRS plus guideline on the occurrence of a patent ductus arteriosus (RR 1.96, 95% CI 0.94 to 4.08; one trial; 166 participants); chronic lung disease (RR 1.27, 95% CI 0.94 to 1.50; one trial; 166 participants); necrotising enterocolitis (RR 0.83, 95% CI 0.33 to 1.94; one trial; 166 participants); and retinopathy of prematurity (RR 1.64, 95% CI 0.75 to 3.00; one trial; 166 participants). There were no serious adverse events in any of the intervention groups. NIRS plus guideline caused more skin marks from the NIRS sensor in the control group than in the experimental group (unadjusted RR 0.31, 95% CI 0.10 to 0.92; one trial; 166 participants). There are no data regarding neurodevelopmental outcome, renal impairment or air leaks.The quality of evidence for all comparisons discussed above was assessed as very low apart from all-cause mortality and adverse events: these were assessed as low and moderate, respectively. The validity of all comparisons is hampered by a small sample of randomised infants, risk of bias due to lack of blinding, and indirectness of outcomes.

AUTHORS' CONCLUSIONS

The only eligible randomised clinical trial did not demonstrate any consistent effects of NIRS plus a guideline on the assessed clinical outcomes. The trial was, however, only powered to detect difference in cerebral oxygenation, not morbidities or mortality. Our systematic review did not reach sufficient power to prove or disprove effects on clinical outcomes. Further randomised clinical trials with low risks of bias and low risks of random errors are needed.

How to assess hemodynamic status in very preterm newborns in the first week of life?

BACKGROUND

Assessing hemodynamic status in preterm newborns is an essential task, as many studies have shown increased morbidity when hemodynamic parameters are abnormal. Although oscillometric monitoring of arterial blood pressure (BP) is widely used due to its simplicity and lack of side effects, these values are not always correlated with microcirculation and oxygen delivery.

OBJECTIVES

This review focuses on different tools for the assessment of hemodynamic status in preterm newborns. These include the measurement of clinical (BP, capillary refill time and urinary output (UO)) or biological parameters (lactate analysis), functional echocardiography, and near-infrared spectroscopy (NIRS). We describe the concepts and techniques involved in these tools in detail, and examine the interest and limitations of each type of assessment.

CONCLUSIONS

This review highlights the complementarities between the different parameters used to assess hemodynamic status in preterm newborns during the first week of life. The analysis of arterial BP measured by oscillometric monitoring must take into account other clinical data, in particular capillary refill time and UO, and biological data such as lactate levels. Echocardiography improves noninvasive hemodynamic management in newborns but requires specific training. In contrast, NIRS may be useful in monitoring the clinical course of infants at risk of, or presenting with, hypotension. It holds the potential for early and noninvasive identification of silent hypoperfusion in critically ill preterm infants. However, more data are needed to confirm the usefulness of this promising tool in significantly changing the outcome of these infants.

Hemodynamic Assessment and Monitoring of Premature Infants

The management of the hemodynamic status of critically ill preterm infants, particularly around the periviable period, remains a significant challenge in the neonatal intensive care unit for a multitude of reasons. The causes of hemodynamic compromise in this population are heterogeneous and usually superimposed on the complex physiologic processes that occur during transition from fetal to neonatal life. This review outlines the unique nature of low blood flow states in this population and present an overview of the current methods for identification and assessment of hemodynamic compromise.

Early biomarkers of brain injury and cerebral hypo- and hyperoxia in the SafeBoosC II trial

BACKGROUND

The randomized clinical trial, SafeBoosC II, examined the effect of monitoring of cerebral oxygenation by near-infrared spectroscopy combined with a guideline on treatment when cerebral oxygenation was out of the target range. Data on cerebral oxygenation was collected in both the intervention and the control group. The primary outcome was the reduction in the burden of cerebral hypo- and hyperoxia between the two groups. In this study we describe the associations between the burden of cerebral hypo- and hyperoxia, regardless of allocation to intervention or control group, and the biomarkers of brain injury from birth till term equivalent age that was collected as secondary and explorative outcomes in the SafeBoosC II trial.

METHODS

Cerebral oxygenation was continuously monitored during the first 72h of life in 166 extremely preterm infants. Cranial ultrasound was performed at day 1,4,7,14, and 35 and at term. Electroencephalogram (EEG) was recorded at 64h. Blood-samples taken at 6 and 64 hours were analysed for the brain injury biomarkers; S100beta, brain-fatty-acid-binding-protein, and neuroketal. All analyses were conducted post hoc.

RESULTS

Significantly more infants with a cerebral burden of hypoxia within the 4th quartile versus infants within quartile 1-3 were diagnosed with severe intracranial haemorrhage (11/39 versus 11/117, p = 0.003), had low burst rate on EEG (12/28 versus 21/103, p = 0.015), or died (14/41 versus 18/123, p = 0.006), whereas none of these events were significantly associated with cerebral hyperoxia. The blood biomarkers were not significantly associated with the burden of cerebral hypo- or hyperoxia.

CONCLUSIONS

The explorative analysis showed that early burden of cerebral hypoxia, but not hyperoxia was significantly associated with low brain electrical activity and severe intracranial haemorrhage while none of the three blood biomarkers were associated with the burden of either cerebral hypo- or hyperoxia.

Research Opportunities to Improve Neonatal Red Blood Cell Transfusion

Red blood cell (RBC) transfusion is a common and lifesaving therapy for anemic neonates and infants, particularly among those born prematurely or undergoing surgery. However, evidence-based indications for when to administer RBCs and adverse effects of RBC transfusion on important outcomes including necrotizing enterocolitis, survival, and long-term neurodevelopmental impairment remain uncertain. In addition, blood-banking practices for preterm and term neonates and infants have been largely developed using studies from older children and adults. Use of and refinements in emerging technologies and advances in biomarker discovery and neonatal-specific RBC transfusion databases may allow clinicians to better define and tailor RBC transfusion needs and practices to individual neonates. Decreasing the need for RBC transfusion and developing neonatal-specific approaches in the preparation of donor RBCs have potential for reducing resource utilization and cost, improving outcomes, and assuring blood safety. Finally, large donor-recipient-linked cohort studies can provide data to better understand the balance of the risks and benefits of RBC transfusion in neonates. These studies may also guide the translation of new research into best practices that can rapidly be integrated into routine care. This review highlights key opportunities in transfusion medicine and neonatology for improving the preparation and transfusion of RBCs into neonates and infants. We focus on timely, currently addressable knowledge gaps that can increase the safety and efficacy of preterm and term neonatal and infant RBC transfusion practices.

Cerebral oximetry in preterm infants: an agenda for research with a clear clinical goal

Preterm birth constitutes a major cause of death before 5 years of age and it is a major cause of neurodevelopmental impairment across the world. Preterm infants are most unstable during the transition between fetal and newborn life during the first days of life and most brain damage occurs in this period. The brain of the preterm infant is accessible for tissue oximetry by near-infrared spectroscopy. Cerebral oximetry has the potential to improve the long-term outcome by helping to tailor the support of respiration and circulation to the individual infant's needs, but the evidence is still lacking. The goals for research include testing the benefit and harms of cerebral oximetry in large-scale randomized trials, improved definition of the hypoxic threshold, better understanding the effects of intensive care on cerebral oxygenation, as well as improved precision of oximeters and calibration among devices or standardization of values in the hypoxic range. These goals can be pursued in parallel.