Neonatal cerebrovascular autoregulation

Brain MRI Injury Patterns across Gestational Age among Preterm Infants with Perinatal Asphyxia

INTRODUCTION

Brain injury patterns of preterm infants with perinatal asphyxia (PA) are underreported. We aimed to explore brain magnetic resonance imaging (MRI) findings and associated neurodevelopmental outcomes in these newborns.

METHODS

Retrospective multicenter study included infants with gestational age (GA) 24.0-36.0 weeks and PA, defined as ≥2 of the following: (1) umbilical cord pH ≤7.0, (2) 5-min Apgar score ≤5, and (3) fetal distress or systemic effects of PA. Findings were compared between GA <28.0 (group 1), 28.0-31.9 (group 2), and 32.0-36.0 weeks (group 3). Early MRI (<36 weeks postmenstrual age or <10 postnatal days) was categorized according to predominant injury pattern, and MRI around term-equivalent age (TEA, 36.0-44.0 weeks and ≥10 postnatal days) using the Kidokoro score. Adverse outcomes included death, cerebral palsy, epilepsy, severe hearing/visual impairment, or neurodevelopment <-1 SD at 18-24 months corrected age.

RESULTS

One hundred nineteen infants with early MRI (n = 94) and/or MRI around TEA (n = 66) were included. Early MRI showed predominantly hemorrhagic injury in groups 1 (56%) and 2 (45%), and white matter (WM)/watershed injury in group 3 (43%). Around TEA, WM scores were highest in groups 2 and 3. Deep gray matter (DGM) (aOR 15.0, 95% CI: 3.8-58.9) and hemorrhagic injury on early MRI (aOR 2.5, 95% CI: 1.3-4.6) and Kidokoro WM (aOR 1.3, 95% CI: 1.0-1.6) and DGM sub-scores (aOR 4.8, 95% CI: 1.1-21.7) around TEA were associated with adverse neurodevelopmental outcomes.

CONCLUSION

The brain injury patterns following PA in preterm infants differ across GA. Particularly DGM abnormalities are associated with adverse neurodevelopmental outcomes.

Cerebral oxygenation saturation in childhood: difference by age and comparison of two cerebral oximetry algorithms

Few reports are available on the monitoring of regional cerebral oxygen saturation (rSO2) in pediatric patients undergoing non-cardiac surgical procedures. In addition, no study has examined the rSO2 levels in children of a broad age range. In this study, we aimed to assess and compare rSO2 levels in pediatric patients of different age groups undergoing non-cardiac surgery. We used two oximeters, tNIRS-1, which uses time-resolved spectroscopy, and conventional INVOS 5100C. Seventy-eight children-26 infants, 26 toddlers, and 26 schoolchildren-undergoing non-cardiac surgery were included. We investigated the differences in the rSO2 levels among the age groups and the correlation between the models and physiological factors influencing the rSO2 values. rSO2 measured by INVOS 5100C was significantly lower in infants than those in other patients. rSO2 measured by tNIRS-1 was higher in the toddler group than those in the other groups. The rSO2 values of tNIRS-1 and INVOS 5100C were moderately correlated (r = 0.41); however, those of INVOS 5100C were approximately 20% higher, and a ceiling effect was observed. The values in INVOS 5100C and tNIRS-1 were affected by blood pressure and the minimum alveolar concentration of sevoflurane, respectively. In pediatric patients undergoing non-cardiac surgery, rSO2 values differed across the three age groups, and the pattern of these differences varied between the two oximeters employing different algorithms. Further research must be conducted to clarify cerebral oxygenation in children.

Assessment of Autoregulation of the Cerebral Circulation during Acute Lung Injury in a Neonatal Porcine Model

In neonates with acute lung injury (ALI), targeting lower oxygenation saturations is suggested to limit oxygen toxicity while maintaining vital organ function. Although thresholds for cerebral autoregulation are studied for the management of premature infants, the impact of hypoxia on hemodynamics, tissue oxygen consumption and extraction is not well understood in term infants with ALI. We examined hemodynamics, cerebral autoregulation and fractional oxygen extraction, as measured by near-infrared spectroscopy (NIRS) and blood gases, in a neonatal porcine oleic acid injury model of moderate ALI. We hypothesized that in ALI animals, cerebral oxygen extraction would be increased to a greater degree than kidney or gut oxygen extraction as indicative of the brain's adaptive efforts to increase cerebral oxygen extraction at the expense of splanchnic end organs. Fifteen anesthetized, ventilated 5-day-old neonatal piglets were divided into moderate lung injury by treatment with oleic acid or control (sham injection). The degree of lung injury was quantified at baseline and after establishment of ALI by blood gases, ventilation parameters and calculated oxygenation deficit, hemodynamic indices by echocardiography and lung injury score by ultrasound. PaCO2 was maintained constant during ventilation. Cerebral, renal and gut oxygenation was determined by NIRS during stepwise decreases in inspired oxygen from 50% to 21%, correlated with PaO2 and PvO2; changes in fractional oxygen extraction (ΔFOE) were calculated from NIRS and from regional blood gas samples. The proportion of cerebral autoregulation impairment attributable to blood pressure, and to hypoxemia, was calculated from autoregulation nomograms. ALI manifested as hypoxemia with increasing intrapulmonary shunt fraction, decreased lung compliance and increased resistance, and marked increase in lung ultrasound score. Brain, gut and renal NIRS, obtained from probes placed over the anterior skull, central abdomen and flank, respectively, correlated with concurrent SVC (brain) or IVC (gut, renal) PvO2 and SvO2. Cerebral autoregulation was impaired after ALI as a function of blood pressure at all FiO2 steps, but predominantly by hypoxemia at FiO2 < 40%. Cerebral ΔFOE was higher in ALI animals at all FiO2 steps. We conclude that in an animal model of neonatal ALI, cerebrovascular blood flow regulation is primarily dependent on oxygenation. There is not a defined oxygenation threshold below which cerebral autoregulation is impaired in ALI. Cerebral oxygen extraction is enhanced in ALI, reflecting compensation for exhausted cerebral autoregulation due to the degree of hypoxemia and/or hypotension, thereby protecting against tissue hypoxia.

Effect of early clinical management on metabolic acidemia in neonates with hypoxic-ischemic encephalopathy

OBJECTIVE

To determine the safety and effectiveness of sodium bicarbonate administration in the management of metabolic acidemia and short-term outcomes in neonates with hypoxic-ischemic encephalopathy (HIE).

STUDY DESIGN

Retrospective cohort study of neonates born at ≥35 weeks of gestation and receiving therapeutic hypothermia. Demographics, pH, lactate, base deficit, treatment, MRI findings, seizure incidence, death prior to discharge were collected.

RESULTS

There was higher mortality (p = 0.010) and injury on MRI (p = 0.008)-primarily deep gray matter (p < 0.001) and cortical injury (p = 0.003)-in the bicarbonate group compared to controls in univariate analysis. The combined outcome of death or abnormal MRI was not significantly associated (OR 1.97, 95% CI 0.80-4.87, p = 0.141) with bicarbonate administration when adjusting for sex, 5-minute Apgar, and initial base deficit.

CONCLUSION

This study demonstrated association between bicarbonate use after HIE and negative short-term outcomes. Future prospective trials could overcome the treatment bias limitation demonstrated in this retrospective study.

Macroperiodic Oscillations: A Potential Novel Biomarker of Outcome in Neonatal Encephalopathy

PURPOSE

Neonatal encephalopathy (NE) is a common cause of neurodevelopmental morbidity. Tools to accurately predict outcomes after therapeutic hypothermia remain limited. We evaluated a novel EEG biomarker, macroperiodic oscillations (MOs), to predict neurodevelopmental outcomes.

METHODS

We conducted a secondary analysis of a randomized controlled trial of neonates with moderate-to-severe NE who underwent standardized clinical examination, magnetic resonance (MR) scoring, video EEG, and neurodevelopmental assessment with Bayley III evaluation at 18 to 24 months. A non-NE cohort of neonates was also assessed for the presence of MOs. The relationship between clinical examination, MR score, MOs, and neurodevelopmental assessment was analyzed.

RESULTS

The study included 37 neonates with 24 of whom survived and underwent neurodevelopmental assessment (70%). The strength of MOs correlated with severity of clinical encephalopathy. MO strength and spread significantly correlated with Bayley III cognitive percentile ( P = 0.017 and 0.046). MO strength outperformed MR score in predicting a combined adverse outcome of death or disability ( P = 0.019, sensitivity 100%, specificity 77% vs. P = 0.079, sensitivity 100%, specificity 59%).

CONCLUSIONS

MOs are an EEG-derived, quantitative biomarker of neurodevelopmental outcome that outperformed a comprehensive validated MRI injury score and a detailed systematic discharge examination in this small cohort. Future work is needed to validate MOs in a larger cohort and elucidate the underlying pathophysiology of MOs.

Postnatal Cerebral Hemodynamics and Placental Vascular Malperfusion Lesions in Neonates With Congenital Heart Disease

BACKGROUND

Neonates with congenital heart disease (CHD) have smaller brain volume at birth. High rates of placental vascular malperfusion lesions may play a role in disrupted brain development.

METHODS

This is a single-center retrospective cohort study of infants born between 2010 and 2019 who were diagnosed with a major cardiac defect requiring surgery in the first year of life. Doppler ultrasound RI of the middle cerebral artery (MCA) and anterior cerebral artery were calculated within the first 72 hours of life. Placentas were evaluated using a standardized approach.

RESULTS

Over the study period, there were 52 patients with hypoplastic left heart syndrome (HLHS), 22 with single-ventricle right ventricular outflow tract obstruction (SV-RVOTO), 75 with a two-ventricle cardiac defect (2V), and 25 with transposition of the great arteries (TGA). MCA Doppler RI were significantly higher for all subgroups of CHD compared with control subjects (0.68 ± 0.11 in control subjects compared with 0.78 ± 0.13 in HLHS, P = 0.03; 0.77 ± 0.10 in SV-RVOTO, P = 0.002; 0.78 ± 0.13 in 2V, P = 0.03; and 0.80 ± 0.14 in TGA; P = 0.001) with the highest average MCA RI in the TGA group. In subgroup analyses, placental fetal vascular malperfusion in the 2V group was associated with higher MCA RI, but this relationship was not present in other subgroups, nor in regards to maternal vascular malperfusion.

CONCLUSIONS

Major forms of CHD are associated with significantly higher cerebral artery RI postnatally, but placental vascular malperfusion lesions may not contribute to this hemodynamic adaptation.

Multimodal neuromonitoring in the pediatric intensive care unit

Neuromonitoring is used to assess the central nervous system in the intensive care unit. The purpose of neuromonitoring is to detect neurologic deterioration and intervene to prevent irreversible nervous system dysfunction. Neuromonitoring starts with the standard neurologic examination, which may lag behind the pathophysiologic changes. Additional modalities including continuous electroencephalography (CEEG), multiple physiologic parameters, and structural neuroimaging may detect changes earlier. Multimodal neuromonitoring now refers to an integrated combination and display of non-invasive and invasive modalities, permitting tailored treatment for the individual patient. This chapter reviews the non-invasive and invasive modalities used in pediatric neurocritical care.

The prediction of estimated cerebral perfusion pressure with trans-systolic time in preterm and term infants

It is important to monitor cerebral perfusion in infants because hypo- and hyperperfusion can contribute to neurological injury. This study aimed to clarify the relationship between trans-systolic time (TST) and critical closing pressure (CrCP) or estimated cerebral perfusion pressure (CPPe) in neonates. Moreover, we aimed to determine the TST values in preterm and term infants with stable cerebral perfusion to clarify normative reference data. This multicentre prospective study included infants with arterial lines admitted to the neonatal intensive care units between December 2021 and August 2023. TST, CrCP, and CPPe were calculated using middle cerebral artery waveforms recorded using transcranial Doppler ultrasonography when clinicians collected arterial blood samples. Three hundred and sixty samples were obtained from 112 infants with a gestational age of 32 (interquartile range, 27-37) weeks and a birth weight of 1481 (956-2355) g. TST was positively correlated with CPPe (r = 0.60, p < 0.001), but not with CrCP (r = 0.08, p = 0.10). The normative reference values of TST in preterm and term infants without samples of hyper- or hypocapnia and/or hyper- or hypotension, which may affect cerebral perfusion, were as follows: ≤ 29 weeks, 0.12 (0.11-0.14) s; 30-36 weeks, 0.14 (0.12-0.15) s; and ≥ 37 weeks, 0.16 (0.14-0.17) s, respectively.  Conclusion: TST in neonates significantly correlated with CPPe, but not with CrCP. TST may be a good predictor of cerebral perfusion and potentially have wider clinical applications. What is Known: • Trans-systolic time (TST) is used in evaluating the effects of increased intracranial pressure on cerebral haemodynamics. However, little is known about the efficacy of TST in predicting neonatal cerebral perfusion pressure. What is New: • This study added evidence that TST correlated with estimated cerebral perfusion pressure, but not with critical closing pressure. Additionally, we showed the normative reference values of the TST in preterm and term infants.

Blood Pressure Goals: Is Cerebral Saturation the New Mean Arterial Pressure?

OBJECTIVE

 The objective of this article was to correlate hypotension and cerebral saturation from near-infrared spectroscopy (cNIRS) in neonates on dopamine.

STUDY DESIGN

 Retrospective review of neonates receiving dopamine between August 2018 and 2019 was performed. Hypotension thresholds included mean arterial pressure (MAP) of postmenstrual age (PMA) ± 5 and 30 mm Hg and gestational age (GA) ± 5 mm Hg. Time below threshold MAP was compared with time with cerebral hypoxia (cNIRS <55%).

RESULTS

 Hypotension occurred 6 to 33% of the time on dopamine in 59 cases. Hypotension did not correlate with abnormal cNIRS overall, within PMA subgroups or by outcomes. Hypotensive periods with MAP < GA had fewer corresponding percent time with abnormal cNIRS events (3.7 ± 1.3%) compared with MAP < PMA (11.9 ± 4.9%, p < 0.003) or 30 mm Hg thresholds (12.2 ± 4.7%, p < 0.0001). In most premature infants, mean cNIRS values during hypotension were still within normal range (57 ± 6%).

CONCLUSION

 cNIRS may be a more clinically relevant measure than MAP for the assessment of neonatal hypotension.

KEY POINTS

· Hypotension occurred 6 to 33% of the time on dopamine in 59 cases.. · Hypotension did not correlate with abnormal cNIRS overall, within PMA subgroups or by outcomes.. · MAP. · We found no cNIRS difference between IVH grades, mortality, average Hct, lactates, or urine output.. · cNIRS may be a more clinically relevant measure than MAP for the assessment of neonatal hypotension..

Cerebrovascular responses to a 90° tilt in healthy neonates

BACKGROUND

Tilts can induce alterations in cerebral hemodynamics in healthy neonates, but prior studies have only examined systemic parameters or used small tilt angles (<90°). The healthy neonatal population, however, are commonly subjected to large tilt angles (≥90°). We sought to characterize the cerebrovascular response to a 90° tilt in healthy term neonates.

METHODS

We performed a secondary descriptive analysis on 44 healthy term neonates. We measured cerebral oxygen saturation (rcSO2), oxygen saturation (SpO2), heart rate (HR), breathing rate (BR), and cerebral fractional tissue oxygen extraction (cFTOE) over three consecutive 90° tilts. These parameters were measured for 2-min while neonates were in a supine (0°) position and 2-min while tilted to a sitting (90°) position. We measured oscillometric mean blood pressure (MBP) at the start of each tilt.

RESULTS

rcSO2 and BR decreased significantly in the sitting position, whereas cFTOE, SpO2, and MBP increased significantly in the sitting position. We detected a significant position-by-time interaction for all physiological parameters.

CONCLUSION

A 90° tilt induces a decline in rcSO2 and an increase in cFTOE in healthy term neonates. Understanding the normal cerebrovascular response to a 90° tilt in healthy neonates will help clinicians to recognize abnormal responses in high-risk infant populations.

IMPACT

Healthy term neonates (≤14 days old) had decreased cerebral oxygen saturation (~1.1%) and increased cerebral oxygen extraction (~0.01) following a 90° tilt. We detected a significant position-by-time interaction with all physiological parameters measured, suggesting the effect of position varied across consecutive tilts. No prior study has characterized the cerebral oxygen saturation response to a 90° tilt in healthy term neonates.

Cerebral perfusion differences are linked to executive function performance in very preterm-born children and adolescents

Children and adolescents born very preterm are at risk of cognitive impairment, particularly affecting executive functions. To date, the neural correlates of these cognitive differences are not yet fully understood, although converging evidence points to a pattern of structural and functional brain alterations, including reduced brain volumes, altered connectivity, and altered brain activation patterns. In very preterm neonates, alterations in brain perfusion have also been reported, but the extent to which these perfusion alterations persist into later childhood is not yet known. This study evaluated global and regional brain perfusion, measured with arterial spin labelling (ASL) MRI, in 26 very preterm children and adolescents and 34 term-born peers. Perfusion was compared between groups and relative to executive function (EF) scores, derived from an extensive EF battery assessing working memory, cognitive flexibility, and planning. Very preterm children and adolescents showed regions of altered perfusion, some of which were also related to EF scores. Most of these regions were located in the right hemisphere and included regions like the thalamus and hippocampus, which are known to play a role in executive functioning and can be affected by prematurity. In addition, perfusion decreased with age during adolescence and showed a significant interaction between birth status and sex, such that very preterm girls showed lower perfusion than term-born girls, but this trend was not seen in boys. Taken together, our results indicate a regionally altered perfusion in very preterm children and adolescents, with age and sex related changes during adolescence.

Impact on cerebral hemodynamics of the use of volume guarantee combined with high frequency oscillatory ventilation in a neonatal animal respiratory distress model

High-frequency oscillatory ventilation (HFOV) is an alternative to conventional mechanical ventilation (CMV). Recently, the use of volume guarantee (VG) combined with HFOV has been suggested as a safe strategy capable of reducing the damage induced by ventilation in immature lungs. However, the possible impact of this new ventilation technique on cerebral hemodynamics is unknown. To evaluate the cerebral hemodynamics effect of HFOV combined with VG in an experimental animal model of neonatal respiratory distress syndrome (RDS) due to surfactant deficiency compared with HFOV and CMV+VG (control group). Eighteen newborn piglets were randomized, before and after the induction of RDS by bronchoalveolar lavage, into 3 mechanical ventilation groups: CMV, HFOV and HFOV with VG. Changes in cerebral oxygen transport and consumption and cerebral blood flow were analyzed by non-invasive regional cerebral oxygen saturation (CrSO2), jugular venous saturation (SjO2), the calculated cerebral oxygen extraction fraction (COEF), the calculated cerebral fractional tissue oxygen extraction (cFTOE) and direct measurement of carotid artery flow. To analyze the temporal evolution of these variables, a mixed-effects linear regression model was constructed. After randomization, the following statistically significant results were found in every group: a drop in carotid artery flow: at a rate of -1.7 mL/kg/min (95% CI: -2.5 to -0.81; p < 0.001), CrSO2: at a rate of -6.2% (95% CI: -7.9 to -4.4; p < 0.001) and SjO2: at a rate of -20% (95% CI: -26 to -15; p < 0.001), accompanied by an increase in COEF: at a rate of 20% (95% CI: 15 to 26; p < 0.001) and cFTOE: at a rate of 0.07 (95% CI: 0.05 to 0.08; p < 0.001) in all groups. No statistically significant differences were found between the HFOV groups.

CONCLUSION

No differences were observed at cerebral hemodynamic between respiratory assistance in HFOV with and without VG, being the latter ventilatory strategy equally safe.

WHAT IS KNOWN

• Preterm have a situation of fragility of cerebral perfusion wich means that any mechanical ventilation strategy can have a significant influence. High-frequency oscillatory ventilation (HFOV) is an alternative to conventional mechanical ventilation (CMV). Recently, the use of volume guarantee (VG) combined with HFOV has been suggested as a safe strategy capable of reducing the damage induced by ventilation in immature lungs. Several studies have compared CMV and HFOV and their effects at hemodynamic level. It is known that the use of high mean airway pressure in HFOV can cause an increase in pulmonary vascular resistance with a decrease in thoracic venous return.

WHAT IS NEW

• The possible impact of VAFO + VG on cerebral hemodynamics is unknown. Due the lack of studies and the existing controversy, we have carried out this research project in an experimental animal model with the aim of evaluating the cerebral hemodynamic repercussion of the use of VG in HFOV compared to the classic strategy without VG.

Cerebral autoregulation monitoring using the cerebral oximetry index after neonatal cardiac surgery: A single-center retrospective cohort study

OBJECTIVE

To investigate whether cerebral autoregulation is impaired after neonatal cardiac surgery and whether changes in autoregulation metrics are associated with different congenital heart defects or the incidence of postoperative neurologic events.

METHODS

This is a retrospective observational study of neonates undergoing monitoring during the first 72 hours after cardiac surgery. Archived data were processed to calculate the cerebral oximetry index (COx) and derived metrics. Acute neurologic events were identified by an electronic medical record review. The Skillings-Mack test and the Wilcoxon signed-rank test were used to analyze the evolution of autoregulation metrics over time; the Mann-Whitney U test was used for comparison between groups.

RESULTS

We included 28 neonates, 7 (25%) with hypoplastic left heart syndrome and 21 (75%) with transposition of the great arteries. Overall, the median percentage of time spent with impaired autoregulation, defined as percentage of time with a COx >0.3, was 31.6% (interquartile range, 21.1%-38.3%). No differences in autoregulation metrics between different cardiac defects subgroups were observed. Seven patients (25%) experienced a postoperative acute neurologic event. Compared to the neonates without an acute neurologic event, those with an acute neurologic event had a higher COx (0.16 vs 0.07; P = .035), a higher percentage of time with a COx >0.3 (39.4% vs 29.2%; P = .017), and a higher percentage of time with a mean arterial pressure below the lower limit of autoregulation (13.3% vs 6.9%; P = .048).

CONCLUSIONS

COx monitoring after cardiac surgery allowed for the detection of impaired cerebral autoregulation, which was more frequent in neonates with postoperative acute neurologic events.

Brain injury and long-term outcome after neonatal surgery for non-cardiac congenital anomalies

BACKGROUND

There is growing evidence that neonatal surgery for non-cardiac congenital anomalies (NCCAs) in the neonatal period adversely affects long-term neurodevelopmental outcome. However, less is known about acquired brain injury after surgery for NCCA and abnormal brain maturation leading to these impairments.

METHODS

A systematic search was performed in PubMed, Embase, and The Cochrane Library on May 6, 2022 on brain injury and maturation abnormalities seen on magnetic resonance imaging (MRI) and its associations with neurodevelopment in neonates undergoing NCCA surgery the first month postpartum. Rayyan was used for article screening and ROBINS-I for risk of bias assessment. Data on the studies, infants, surgery, MRI, and outcome were extracted.

RESULTS

Three eligible studies were included, reporting 197 infants. Brain injury was found in n = 120 (50%) patients after NCCA surgery. Sixty (30%) were diagnosed with white matter injury. Cortical folding was delayed in the majority of cases. Brain injury and delayed brain maturation was associated with a decrease in neurodevelopmental outcome at 2 years of age.

CONCLUSIONS

Surgery for NCCA was associated with high risk of brain injury and delay in maturation leading to delay in neurocognitive and motor development. However, more research is recommended for strong conclusions in this group of patients.

IMPACT

Brain injury was found in 50% of neonates who underwent NCCA surgery. NCCA surgery is associated with a delay in cortical folding. There is an important research gap regarding perioperative brain injury and NCCA surgery.

Preterm infants variability in cerebral near-infrared spectroscopy measurements in the first 72-h after birth

BACKGROUND

Cerebral near-infrared spectroscopy is a non-invasive tool used to measure regional cerebral tissue oxygenation (rScO2) initially validated in adult and pediatric populations. Preterm neonates, vulnerable to neurologic injury, are attractive candidates for NIRS monitoring; however, normative data and the brain regions measured by the current technology have not yet been established for this population.

METHODS

This study's aim was to analyze continuous rScO2 readings within the first 6-72 h after birth in 60 neonates without intracerebral hemorrhage born at ≤1250 g and/or ≤30 weeks' gestational age (GA) to better understand the role of head circumference (HC) and brain regions measured.

RESULTS

Using a standardized brain MRI atlas, we determined that rScO2 in infants with smaller HCs likely measures the ventricular spaces. GA is linearly correlated, and HC is non-linearly correlated, with rScO2 readings. For HC, we infer that rScO2 is lower in infants with smaller HCs due to measuring the ventricular spaces, with values increasing in the smallest HCs as the deep cerebral structures are reached.

CONCLUSION

Clinicians should be aware that in preterm infants with small HCs, rScO2 displayed may reflect readings from the ventricular spaces and deep cerebral tissue.

IMPACT

Clinicians should be aware that in preterm infants with small head circumferences, cerebral near-infrared spectroscopy readings of rScO2 displayed may reflect readings from the ventricular spaces and deep cerebral tissue. This highlights the importance of rigorously re-validating technologies before extrapolating them to different populations. Standard rScO2 trajectories should only be established after determining whether the mathematical models used in NIRS equipment are appropriate in premature infants and the brain region(s) NIRS sensors captures in this population, including the influence of both gestational age and head circumference.

Cerebral Hemodynamic and Metabolic Abnormalities in Neonatal Hypocalcemia: Findings from Advanced MRI

BACKGROUND AND PURPOSE

Neonatal hypocalcemia is the most common metabolic disorder, and whether asymptomatic disease should be treated with calcium supplements remains controversial. We aimed to quantify neonatal hypocalcemia's global CBF and cerebral metabolic rate of oxygen (CMRO2) using physiologic MR imaging and elucidate the pathophysiologic vulnerabilities of neonatal hypocalcemia.

MATERIALS AND METHODS

A total of 37 consecutive patients with neonatal hypocalcemia were enrolled. They were further divided into subgroups with and without structural MR imaging abnormalities, denoted as neonatal hypocalcemia-a (n = 24) and neonatal hypocalcemia-n (n = 13). Nineteen healthy neonates were enrolled as a control group. Brain physiologic parameters determined using phase-contrast MR imaging, T2-relaxation-under-spin-tagging MR imaging, and brain volume were compared between patients with neonatal hypocalcemia (their subgroups) and controls. Predictors for neonatal hypocalcemia-related brain injuries were identified using multivariate logistic regression analysis and expressed as ORs with 95% CIs.

RESULTS

Patients with neonatal hypocalcemia showed significantly lower CBF and CMRO2 compared with controls. Furthermore, the neonatal hypocalcemia-a subset (versus controls or neonatal hypocalcemia-n) had significantly lower CBF and CMRO2. There was no obvious difference in CBF and CMRO2 between the neonatal hypocalcemia-n subset and controls. CBF and CMRO2 were independently associated with neonatal hypocalcemia. The ORs were 0.80 (95% CI, 0.65-0.99) and 0.97 (95% CI, 0.89-1.05) for CBF and CMRO2, respectively.

CONCLUSIONS

Neonatal hypocalcemia with structural damage may exhibit lower hemodynamics and cerebral metabolism. CBF may be useful in assessing the need for calcium supplementation in asymptomatic neonatal hypocalcemia to prevent brain injury.

Comparison of Near-Infrared Spectroscopy-Based Cerebral Autoregulatory Indices in Extremely Low Birth Weight Infants

BACKGROUND

Premature infants are born with immature cerebral autoregulation function and are vulnerable to pressure passive cerebral circulation and subsequent brain injury. Measurements derived from near-infrared spectroscopy (NIRS) have enabled continuous assessment of cerebral vasoreactivity. Although NIRS has enabled a growing field of research, the lack of clear standardization in the field remains problematic. A major limitation of current literature is the absence of a comparative analysis of the different methodologies.

OBJECTIVES

To determine the relationship between NIRS-derived continuous indices of cerebral autoregulation in a cohort of extremely low birth weight (ELBW) infants.

METHODS

Premature infants of birth weight 401-1000 g were studied during the first 72 h of life. The cerebral oximetry index (COx), hemoglobin volume index (HVx), and tissue oxygenation heart rate reactivity index (TOHRx) were simultaneously calculated. The relationship between each of the indices was assessed with Pearson correlation.

RESULTS

Fifty-eight infants with a median gestational age of 25.8 weeks and a median birth weight of 738 g were included. Intraventricular hemorrhage (IVH) was detected in 33% of individuals. COx and HVx demonstrated the highest degree of correlation, although the relationship was moderate at best (r = 0.543, p < 0.001). No correlation was found either between COx and TOHRx (r = 0.318, p < 0.015) or between HVx and TOHRx (r = 0.287, p < 0.029). No significant differences in these relationships were found with respect to IVH and no IVH in subgroup analysis.

CONCLUSIONS

COx, HVx, and TOHRx are not numerically equivalent. Caution must be applied when interpreting or comparing results based on different methodologies for measuring cerebral autoregulation. Uniformity regarding data acquisition and analytical methodology are needed to firmly establish a gold standard for neonatal cerebral autoregulation monitoring.

Arousal state transitions occlude sensory-evoked neurovascular coupling in neonatal mice

In the adult sensory cortex, increases in neural activity elicited by sensory stimulation usually drive vasodilation mediated by neurovascular coupling. However, whether neurovascular coupling is the same in neonatal animals as adults is controversial, as both canonical and inverted responses have been observed. We investigated the nature of neurovascular coupling in unanesthetized neonatal mice using optical imaging, electrophysiology, and BOLD fMRI. We find in neonatal (postnatal day 15, P15) mice, sensory stimulation induces a small increase in blood volume/BOLD signal, often followed by a large decrease in blood volume. An examination of arousal state of the mice revealed that neonatal mice were asleep a substantial fraction of the time, and that stimulation caused the animal to awaken. As cortical blood volume is much higher during REM and NREM sleep than the awake state, awakening occludes any sensory-evoked neurovascular coupling. When neonatal mice are stimulated during an awake period, they showed relatively normal (but slowed) neurovascular coupling, showing that that the typically observed constriction is due to arousal state changes. These result show that sleep-related vascular changes dominate over any sensory-evoked changes, and hemodynamic measures need to be considered in the context of arousal state changes.

Advanced Neuromonitoring Modalities on the Horizon: Detection and Management of Acute Brain Injury in Children

Timely detection and monitoring of acute brain injury in children is essential to mitigate causes of injury and prevent secondary insults. Increasing survival in critically ill children has emphasized the importance of neuroprotective management strategies for long-term quality of life. In emergent and critical care settings, traditional neuroimaging modalities, such as computed tomography and magnetic resonance imaging (MRI), remain frontline diagnostic techniques to detect acute brain injury. Although detection of structural and anatomical abnormalities remains crucial, advanced MRI sequences assessing functional alterations in cerebral physiology provide unique diagnostic utility. Head ultrasound has emerged as a portable neuroimaging modality for point-of-care diagnosis via assessments of anatomical and perfusion abnormalities. Application of electroencephalography and near-infrared spectroscopy provides the opportunity for real-time detection and goal-directed management of neurological abnormalities at the bedside. In this review, we describe recent technological advancements in these neurodiagnostic modalities and elaborate on their current and potential utility in the detection and management of acute brain injury.

Cord management in non-vigorous newborns

Cord management in non-vigorous newborns remains up for debate, as limited studies have validated strategies in this high-risk population. While multiple national and international governing bodies now recommend the routine practice of delayed cord clamping (DCC) in vigorous neonates, these organizations have not reached a consensus on the appropriate approach in non-vigorous neonates.1 Benefits of placental transfusion are greatly needed amongst non-vigorous neonates who are at risk of asphyxiation-associated mortality and morbidities, but the need for immediate resuscitation complicates matters. This chapter discusses the physiological benefits of placental transfusion for non-vigorous neonates and reviews the available literature on different umbilical cord management strategies for this population.

Continuous monitoring of cerebral blood flow during general anaesthesia in infants

Background

General anaesthesia is associated with neurocognitive deficits in infants after noncardiac surgery. Disturbances in cerebral perfusion as a result of systemic hypotension and impaired autoregulation may be a potential cause. Our aim was to study cerebral blood flow (CBF) velocity continuously during general anaesthesia in infants undergoing noncardiac surgery and compare variations in CBF velocity with simultaneously measured near-infrared spectroscopy (NIRS), blood pressure, and heart rate.

Methods

NeoDoppler, a recently developed ultrasound system, was used to monitor CBF velocity via the anterior fontanelle during induction and maintenance of general anaesthesia until the start of surgery, and during recovery. NIRS, blood pressure, and heart rate were monitored simultaneously and synchronised with the NeoDoppler measurements.

Results

Thirty infants, with a median postmenstrual age at surgery of 37.6 weeks (range 28.6-60.0) were included. Compared with baseline, the trend curves showed a decrease in CBF velocity during induction and maintenance of anaesthesia and returned to baseline values during recovery. End-diastolic velocity decreased in all infants during anaesthesia, on average by 59%, whereas peak systolic- and time-averaged velocities decreased by 26% and 45%, respectively. In comparison, the reduction in mean arterial pressure was only 20%. NIRS values were high and remained stable. When adjusting for mean arterial pressure, the significant decrease in end-diastolic velocity persisted, whereas there was only a small reduction in peak systolic velocity.

Conclusions

Continuous monitoring of CBF velocity using NeoDoppler during anaesthesia is feasible and may provide valuable information about cerebral perfusion contributing to a more targeted haemodynamic management in anaesthetised infants.

A Wearable Fiber-Free Optical Sensor for Continuous Monitoring of Cerebral Blood Flow in Freely Behaving Mice

OBJECTIVE

Wearable technologies for functional brain monitoring in freely behaving subjects can advance our understanding of cognitive processing and adaptive behavior. Existing technologies are lacking in this capability or need procedures that are invasive and/or otherwise impede brain assessments during social behavioral conditions, exercise, and sleep.

METHODS

In response a complete system was developed to combine relative cerebral blood flow (rCBF) measurement, O2 and CO2 supplies, and behavior recording for use on conscious, freely behaving mice. An innovative diffuse speckle contrast flowmetry (DSCF) device and associated hardware were miniaturized and optimized for rCBF measurements in small subject applications. The use of this wearable, fiber-free, near-infrared DSCF head-stage/probe allowed no craniotomy, minimally invasive probe implantation, and minimal restraint of the awake animal.

RESULTS AND CONCLUSIONS

Significant correlations were found between measurements with the new DSCF design and an optical standard. The system successfully detected rCBF responses to CO2-induced hypercapnia in both anesthetized and freely behaving mice.

SIGNIFICANCE

Collecting rCBF and activity information together during natural behaviors provides realistic physiological results and opens the path to exploring their correlations with pathophysiological conditions.

Effect of the change of mechanical ventilation mode on cerebral oxygen saturation level in neonates

BACKGROUND

This study aimed to apply near-infrared spectroscopy (NIRS) to monitor cerebral oxygen saturation (SrO2) level in neonates before and after the change of mechanical ventilation mode, and thus, the effects of the change of mechanical ventilator mode on SrO2 level in neonates were assessed.

METHODS

This trial was designed as an observational study .A total of 70 neonates who were admitted to the Department of Neonatology of Beijing Luhe Hospital Affiliated to Capital Medical University (Beijing, China) between September 2019 and October 2021 and required respiratory support were included. The variations of SrO2 level before and after the change of mechanical ventilation mode, including changing from Synchronized intermittent mandatory ventilation (SIMV) to noninvasive ventilation (NIV, group 1), and from NIV to oxygen inhalation (group 2), were monitored by Enginmed EGOS-600 A. The changes of SrO2 level at 30 min before and 1 h after the change of ventilation mode were compared between the two groups.

RESULTS

The SrO2 level in the group 1 30 min before, as well as 10 min, 30 min, and 1 h after the change of ventilation mode was 62.54 ± 3.36%, 65.43 ± 3.98%, 64.38 ± 4.23%, and 64.63 ± 3.71%, respectively. The SrO2 level at all the points after the change of ventilation mode increased compared with 30 min before the change (P < 0.05). The SrO2 level in the group 2 at each time point was 62.67 ± 4.69%, 64.61 ± 5.00%, 64.04 ± 4.48%, and 64.55 ± 4.32%, respectively. Compared with 30 min before ventilator weaning, the SrO2 level at all the points after ventilator weaning increased (P < 0.05). Peak inspiratory pressure (PIP) excluding Nasal Continuous Positive Airway Pressure (NCPAP)) in group 1 was lower than that before extubation, and the difference was statistically significant (P = 0) (Table 7).

CONCLUSIONS

SrO2 level showed an increasing trend after the change of ventilation mode, and the increase of SrO2 level at 10 min after the change of ventilation mode was the most prominent. From SIMV to NIV, increased SrO2 levels may be associated with decreased PIP.

Developmental Brain Injury and Social Determinants of Health: Opportunities to Combine Preclinical Models for Mechanistic Insights into Recovery

Epidemiological studies show that social determinants of health are among the strongest factors associated with developmental outcomes after prenatal and perinatal brain injuries, even when controlling for the severity of the initial injury. Elevated socioeconomic status and a higher level of parental education correlate with improved neurologic function after premature birth. Conversely, children experiencing early life adversity have worse outcomes after developmental brain injuries. Animal models have provided vital insight into mechanisms perturbed by developmental brain injuries, which have indicated directions for novel therapeutics or interventions. Animal models have also been used to learn how social environments affect brain maturation through enriched environments and early adverse conditions. We recognize animal models cannot fully recapitulate human social circumstances. However, we posit that mechanistic studies combining models of developmental brain injuries and early life social environments will provide insight into pathways important for recovery. Some studies combining enriched environments with neonatal hypoxic injury models have shown improvements in developmental outcomes, but further studies are needed to understand the mechanisms underlying these improvements. By contrast, there have been more limited studies of the effects of adverse conditions on developmental brain injury extent and recovery. Uncovering the biological underpinnings for early life social experiences has translational relevance, enabling the development of novel strategies to improve outcomes through lifelong treatment. With the emergence of new technologies to analyze subtle molecular and behavioral phenotypes, here we discuss the opportunities for combining animal models of developmental brain injury with social construct models to deconvolute the complex interactions between injury, recovery, and social inequity.

Cerebral Blood Flow of the Neonatal Brain after Hypoxic-Ischemic Injury

OBJECTIVE

Hypoxic-ischemic encephalopathy (HIE) in infants can have long-term adverse neurodevelopmental effects and markedly reduce quality of life. Both the initial hypoperfusion and the subsequent rapid reperfusion can cause deleterious effects in brain tissue. Cerebral blood flow (CBF) assessment in newborns with HIE can help detect abnormalities in brain perfusion to guide therapy and prognosticate patient outcomes.

STUDY DESIGN

The review will provide an overview of the pathophysiological implications of CBF derangements in neonatal HIE, current and emerging techniques for CBF quantification, and the potential to utilize CBF as a physiologic target in managing neonates with acute HIE.

CONCLUSION

The alterations of CBF in infants during hypoxia-ischemia have been studied by using different neuroimaging techniques, including nitrous oxide and xenon clearance, transcranial Doppler ultrasonography, contrast-enhanced ultrasound, arterial spin labeling MRI, 18F-FDG positron emission tomography, near-infrared spectroscopy (NIRS), functional NIRS, and diffuse correlation spectroscopy. Consensus is lacking regarding the clinical significance of CBF estimations detected by these different modalities. Heterogeneity in the imaging modality used, regional versus global estimations of CBF, time for the scan, and variables impacting brain perfusion and cohort clinical characteristics should be considered when translating the findings described in the literature to routine practice and implementation of therapeutic interventions.

KEY POINTS

· Hypoxic-ischemic injury in infants can result in adverse long-term neurologic sequelae.. · Cerebral blood flow is a useful biomarker in neonatal hypoxic-ischemic injury.. · Imaging modality, variables affecting cerebral blood flow, and patient characteristics affect cerebral blood flow assessment..

Brain-Oriented Strategies for Neuroprotection of Asphyxiated Newborns in the First Hours of Life

Perinatal asphyxia represents the first cause of severe neurological disabilities and the second cause of neonatal death in term-born babies. Currently, no treatment can prevent immediate cell death from necrosis, but some therapeutic interventions, such as therapeutic hypothermia (TH), can reduce delayed cell death from apoptosis. TH significantly improves the combined outcome of mortality or major neurodevelopmental disability, but the number of patients to be treated is 7 to get 1 child with no adverse neurological outcome. The aim of this educational review is to analyze the other care strategies to be implemented to improve the neurological outcome of children with hypoxic ischemic encephalopathy (HIE). Hypocapnia, hypoglycemia, pain control, and functional brain monitoring are recognized as appropriate approaches to improve outcome in critically ill infants with HIE. Pharmacologic neuroprotective adjuncts are currently under investigation. New drugs such as allopurinol and melatonin seem to provide positive effects although more randomized controlled trials are required to establish the effective therapeutic scheme. In the meantime, sustaining the respiratory, metabolic, and cardiovascular system during TH can be a valuable aid in managing and treating the patient with HIE in an optimal way.

Impact of cardiopulmonary bypass on cerebrovascular autoregulation assessed by ultrafast ultrasound imaging

Newborns with congenital heart disease undergoing cardiac surgery are at risk of neurodevelopmental impairment with limited understanding of the impact of intra-operative cardiopulmonary bypass (CPB), deep hypothermia and selective cerebral perfusion on the brain. We hypothesized that a novel ultrasound technique, ultrafast power Doppler (UPD), can assess variations of cerebral blood volume (CBV) in neonates undergoing cardiac surgery requiring CPB. UPD was performed before, during and after surgery in newborns with hypoplastic left heart syndrome undergoing a Norwood operation. We found that global CBV was not significantly different between patients and controls (P = 0.98) and between pre- and post-surgery (P = 0.62). UPD was able to monitor changes in CBV throughout surgery, revealing regional differences in CBV during hypothermia during which CBV correlated with CPB flow rate (R²  = 0.52, P = 0.021). Brain injury on post-operative magnetic resonance imaging was observed in patients with higher maximum variation in CBV. Our findings suggest that UPD can quantify global and regional brain perfusion variation during neonatal cardiac surgery with this first intra-operative application demonstrating an association between CBV and CPB flow rate, suggesting loss of autoregulation. Therefore, the measurement of CBV by UPD could enable optimization of cerebral perfusion during cardiac surgery in neonates. KEY POINTS: The impact of cardiopulmonary bypass (CPB) on the neonatal brain undergoing cardiac surgery is poorly understood. Ultrafast power Doppler (UPD) quantifies cerebral blood volume (CBV), a surrogate of brain perfusion. CBV varies throughout CPB surgery and is associated with variation of the bypass pump flow rate during deep hypothermia. Association between CBV and bypass pump flow rate suggests loss of cerebrovascular autoregulatory processes. Quantitative monitoring of cerebral perfusion by UPD could provide a direct parameter to optimize CPB flow rate.

Changes in Cerebral Hemodynamics During Systemic Pulmonary Shunt and Pulmonary Artery Banding in Infants with Congenital Heart Disease

Palliative surgery is often performed in the treatment of congenital heart disease. Two representative palliative procedures are the systemic pulmonary shunt and pulmonary artery banding. Dramatic changes in cerebral hemodynamics may occur in these operations due to changes in the pulmonary-to-systemic blood flow ratio and systemic oxygenation. However, there seem to be almost no studies evaluating them. Accordingly, we evaluated cerebral perfusion by transcranial Doppler ultrasonography and cerebral oxygenation by near infrared spectroscopy during these procedures. In the post hoc analysis of a previous prospective observational study, cerebral blood flow velocities of the middle cerebral artery measured by transcranial Doppler were compared between the start and end of surgery as were the pulsatility index and resistance index. The cerebral oxygenation values were also compared between the start and end of surgery. Twenty-two infants with systemic pulmonary shunt and 20 infants with pulmonary artery banding were evaluated. There were no significant differences of the flow velocities between the start and end of surgery in either procedure. The pulsatility index significantly increased after pulmonary artery banding, which may compete with the increase in cerebral perfusion due to the increase in systemic blood flow. The cerebral oxygenation decreased in both procedures, possibly due to an increase in body temperature. Arterial oxygen saturation was almost the same before and after both procedures. Contrary to our expectation, the changes in cerebral hemodynamics in the palliative operations were small if the management of physiological indices such as arterial oxygen saturation was properly performed during the procedures.

Intraoperative monitoring of cerebrovascular autoregulation in infants and toddlers receiving major elective surgery to determine the individually optimal blood pressure - a pilot study

INTRODUCTION

Inducing general anesthesia (GA) in children can considerably affect blood pressure, and the rate of severe critical events owing to this remains high. Cerebrovascular autoregulation (CAR) protects the brain against blood-flow-related injury. Impaired CAR may contribute to the risk of cerebral hypoxic-ischemic or hyperemic injury. However, blood pressure limits of autoregulation (LAR) in infants and children are unclear.

MATERIALS AND METHODS

In this pilot study CAR was monitored prospectively in 20 patients aged <4 years receiving elective surgery under GA. Cardiac- or neurosurgical procedures were excluded. The possibility of calculating the CAR index hemoglobin volume index (HVx), by correlating near-infrared-spectroscopy (NIRS)-derived relative cerebral tissue hemoglobin and invasive mean arterial blood pressure (MAP) was determined. Optimal MAP (MAPopt), LAR, and the proportion of time with a MAP outside LAR were determined.

RESULTS

The mean patient age was 14 ± 10 months. MAPopt could be determined in 19 of 20 patients, with an average of 62 ± 12 mmHg. The required time for a first MAPopt depended on the extent of spontaneous MAP fluctuations. The actual MAP was outside the LAR in 30% ± 24% of the measuring time. MAPopt significantly differed among patients with similar demographics. The CAR range averaged 19 ± 6 mmHg. Using weight-adjusted blood pressure recommendations or regional cerebral tissue saturation, only a fraction of the phases with inadequate MAP could be identified.

CONCLUSION

Non-invasive CAR monitoring using NIRS-derived HVx in infants, toddlers, and children receiving elective surgery under GA was reliable and provided robust data in this pilot study. Using a CAR-driven approach, individual MAPopt could be determined intraoperatively. The intensity of blood pressure fluctuations influences the initial measuring time. MAPopt may differ considerably from recommendations in the literature, and the MAP range within LAR in children may be smaller than that in adults. The necessity of manual artifact elimination represents a limitation. Larger prospective and multicenter cohort studies are necessary to confirm the feasibility of CAR-driven MAP management in children receiving major surgery under GA and to enable an interventional trial design using MAPopt as a target.

Newer indications for neuromonitoring in critically ill neonates

Continuous neuromonitoring in the neonatal intensive care unit allows for bedside assessment of brain oxygenation and perfusion as well as cerebral function and seizure identification. Near-infrared spectroscopy (NIRS) reflects the balance between oxygen delivery and consumption, and use of multisite monitoring of regional oxygenation provides organ-specific assessment of perfusion. With understanding of the underlying principles of NIRS as well as the physiologic factors which impact oxygenation and perfusion of the brain, kidneys and bowel, changes in neonatal physiology can be more easily recognized by bedside providers, allowing for appropriate, targeted interventions. Amplitude-integrated electroencephalography (aEEG) allows continuous bedside evaluation of cerebral background activity patterns indicative of the level of cerebral function as well as identification of seizure activity. Normal background patterns are reassuring while abnormal background patterns indicate abnormal brain function. Combining brain monitoring information together with continuous vital sign monitoring (blood pressure, pulse oximetry, heart rate and temperature) at the bedside may be described as multi-modality monitoring and facilitates understanding of physiology. We describe 10 cases in critically ill neonates that demonstrate how comprehensive multimodal monitoring provided greater recognition of the hemodynamic status and its impact on cerebral oxygenation and cerebral function thereby informing treatment decisions. We anticipate that there are numerous other uses of NIRS as well as NIRS in conjunction with aEEG which are yet to be reported.

Therapeutic Hypothermia Treatment for an Infant with Hypoxic-Ischemic Encephalopathy and Gastroschisis: A Case Report

Gastroschisis is a congenital, typically isolated, full-thickness abdominal wall defect in which the abdominal contents, usually only the small intestine, remain outside the abdominal cavity. It is commonly detected on fetal ultrasonography, and has generally excellent survival and outcomes, though these can be decreased in cases of complicated gastroschisis. We present the case of a female infant with a prenatal diagnosis of gastroschisis who required a prolonged and complex resuscitation after delivery. In addition to her gastroschisis, she presented with a history and physical examination consistent with severe hypoxic-ischemic encephalopathy and was treated with therapeutic hypothermia (TH) without further compromise to her bowel. In addition, careful consideration of neuroprotection, fluid status, bowel viability, and hemodynamics were undertaken in her care. She was discharged home on full enteral feeds, with only mild language and gross motor delays at 6 months of age. To our knowledge, there are no reports in the literature of the use of TH in the setting of unrepaired simple gastroschisis.

The Effect of Electroencephalography Abnormalities on Cerebral Autoregulation in Sedated Ventilated Children

Purpose: To determine the effects of non-ictal electroencephalogram (EEG) changes on cerebrovascular autoregulation (AR) using the cerebral oximetry index (COx). Materials and Methods: Mean arterial blood pressure (MAP), cerebral tissue oxygenation (CrSO2), and EEG were acquired for 96 h. From all of the EEG recordings, 30 min recording segments were extracted using the endotracheal suction events as the guide. EEG recordings were classified as EEG normal and EEG abnormal groups. Each 30 min segment was further divided into six 5 min epochs. Continuous recordings of MAP and CrSO2 by near-infrared spectroscopy (NIRS) were extracted. The COx value was defined as the concordance (R) value of the Pearson correlation between MAP and CrSO2 in a 5 min epoch. Then, an Independent-Samples Mann-Whitney U test was used to analyze the number of epochs within the 30 min segments above various R cutoff values (0.2, 0.3, and 0.4) in normal and abnormal EEG groups. A p-value < 0.05 was considered significant, and all analyses were two-tailed. Results: Among 16 sedated, mechanically ventilated children, 382 EEG recordings of 30 min segments were analyzed. The proportions of epochs in each 30 min segment above the R cutoff values were similar between the EEG normal and EEG abnormal groups (p > 0.05). The median concordance values for CSrO2 and MAP in EEG normal and EEG abnormal groups were similar (0.26 (0.17−0.35) and 0.18 (0.12−0.31); p = 0.09). Conclusions: Abnormal EEG patterns without ictal changes do not affect cerebrovascular autoregulation in sedated and mechanically ventilated children.

Identifying the optimal blood pressure for cerebral autoregulation in infants after cardiac surgery by monitoring cerebrovascular reactivity-A pilot study

BACKGROUND

Advances in the treatment of pediatric congenital heart disease have increased survival rates. Despite efforts to prevent neurological injury, many patients suffer from impaired neurodevelopmental outcomes. Compromised cerebral autoregulation can increase the risk of brain injury following pediatric cardiac surgery with cardiopulmonary bypass. Monitoring autoregulation and maintaining adequate cerebral blood flow can help prevent neurological injury.

AIMS

Our objective was to evaluate autoregulation parameters and to define the optimal blood pressure as well as the lower and upper blood pressure limits of autoregulation.

METHODS

Autoregulation was monitored prospectively in 36 infants after cardiopulmonary bypass surgery for congenital heart defects between January and December 2019. Autoregulation indices were calculated by correlating invasive arterial blood pressure, cortical oxygen saturation, and relative tissue hemoglobin levels with near-infrared spectroscopy parameters.

RESULTS

The mean patient age was 4.1 ± 2.8 months, and the mean patient weight was 5.2 ± 1.8 kg. Optimal mean arterial pressure could be identified in 88.9% of patients via the hemoglobin volume index and in 91.7% of patients via the cerebral oxygenation index, and a lower limit of autoregulation could be found in 66.7% and 63.9% of patients, respectively. No significant changes in autoregulation indices at the beginning or end of the monitoring period were observed. In 76.5% ± 11.1% and 83.8% ± 9.9% of the 8 and 16 h monitoring times, respectively, the mean blood pressure was inside the range of intact autoregulation (below in 21.5% ± 25.4% and 11.3% ± 16.5% and above in 8.7% ± 10.4% and 6.0% ± 11.0%, respectively). The mean optimal blood pressure was 57.4 ± 8.7 mmHg and 58.2 ± 7.9 mmHg and the mean lower limit of autoregulation was 48.8 ± 8.3 mmHg and 45.5 ± 6.7 mmHg when generated via the hemoglobin volume index and cerebral oxygenation index, respectively.

CONCLUSIONS

Postoperative noninvasive autoregulation monitoring after cardiac surgery in children can be reliably and safely performed using the hemoglobin volume index and cerebral oxygenation index and provides robust data. This monitoring can be used to identify individual hemodynamic targets to optimize autoregulation, which differs from those recommended in the literature. Further evaluation of this subject is needed.

Cerebellar development after preterm birth

Preterm birth and its complications and the associated adverse factors, including brain hemorrhage, inflammation, and the side effects of medical treatments, are the leading causes of neurodevelopmental disability. Growing evidence suggests that preterm birth affects the cerebellum, which is the brain region involved in motor coordination, cognition, learning, memory, and social communication. The cerebellum is particularly vulnerable to the adverse effects of preterm birth because key cerebellar developmental processes, including the proliferation of neural progenitors, and differentiation and migration of neurons, occur in the third trimester of a human pregnancy. This review discusses the negative impacts of preterm birth and its associated factors on cerebellar development, focusing on the cellular and molecular mechanisms that mediate cerebellar pathology. A better understanding of the cerebellar developmental mechanisms affected by preterm birth is necessary for developing novel treatment and neuroprotective strategies to ameliorate the cognitive, behavioral, and motor deficits experienced by preterm subjects.

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.

Early Cerebrovascular Autoregulation in Neonates with Congenital Heart Disease

Neonates with congenital heart disease (CHD) display delayed brain development, predisposing them to impaired cerebrovascular autoregulation (CAR) and ischemic brain injury. For this paper, we analyzed the percentage of time with impaired CAR (%time impaired CAR) during the first 72 h after birth, the relation with clinical factors, and survival in 57 neonates with CHD. The primary outcome was a correlation coefficient of cerebral oxygenation (rcSO2) and mean arterial blood pressure (MABP, mmHg) for two hours on a daily basis. The %time impaired CAR ranged from 9.3% of the studied time on day one to 4.6% on day three. Variables associated with more %time impaired CAR were the use of inotropes (day 1, B = 19.5, 95%CI = 10.6–28.3; day 3, B = 11.5, 95%CI = 7.1–16), lower MABP (day 1, B = −0.6, 95%CI = −1.2–0.0), and dextro-transposition of the great arteries (dTGA) (16.2%) compared with other CHD types (2.0–5.0%; day 1, p = 0.022). Survival was not an associated variable. To summarize, impaired CAR was found in CHD neonates in up to 9.3% of the studied time. More evidence is necessary to evaluate an association with inotropes, dTGA, %time impaired CAR, and long-term outcome, further in larger cohorts.

Association Between Early Change in Arterial Carbon Dioxide Tension and Outcomes in Neonates Treated by Extracorporeal Membrane Oxygenation

The primary objective was to investigate the association between partial pressure of carbon dioxide (PaCO2) change after extracorporeal membrane oxygenation (ECMO) initiation and neurologic outcome in neonates treated for respiratory failure. A retrospective analysis of the Extracorporeal Life Support Organization (ELSO) database including newborns supported by ECMO for respiratory indication during 2015-2020. The closest Pre-ECMO (Pre-ECMO PaCO2) and at 24 hours after ECMO initiation (H24 PaCO2) PaCO2 values allowed to calculate the relative change in PaCO2 (Rel Δ PaCO2 = [H24 PaCO2 - Pre-ECMO PaCO2]/Pre-ECMO PaCO2). The primary outcome was the onset of any acute neurologic event (ANE), defined as cerebral bleeding, ischemic stroke, clinical or electrical seizure, or brain death during ECMO. We included 3,583 newborns (median age 1 day [interquartile range {IQR}, 1-3], median weight 3.2 kg [IQR, 2.8-3.6]) from 198 ELSO centers. The median Rel Δ PaCO2 value was -29.9% [IQR, -46.2 to -8.5]. Six hundred nine (17%) of them had ANE (405 cerebral bleedings, 111 ischemic strokes, 225 seizures, and 6 brain deaths). Patients with a decrease of PaCO2 > 50% were more likely to develop ANE than others (odds ratio [OR] 1.78, 95% confidence interval [CI], 1.31-2.42, p < 0.001). This was still observed after adjustment for all clinically relevant confounding factors (adjusted OR 1.94, 95% CI, 1.29-2.92, p = 0.001). A significant decrease in PaCO2 after ECMO start is associated with ANE among neonates requiring ECMO for respiratory failure. Cautious PaCO2 decrease should be considered after start of ECMO therapy.

Pediatric Neuroanesthesia — a Review of the Recent Literature

Purpose of Review

Pediatric neuroanesthesia is a growing and still challenging subspecialty. The purpose of this review is to summarize the available knowledge and highlight the most recent findings of the literature on non-traumatic pediatric neuroanesthesia care.

Recent Findings

Several human studies have confirmed the negative effects of early life anesthetic exposure. According to non-human studies, volatile anesthetics and opioids contribute to tumor progression. Tranexamic acid effectively reduces perioperative blood loss; it is used in several different doses without standard guidelines on optimal dosing. The widespread use of neuromonitoring has necessitated the development of anesthetic methods that do not affect neuromuscular transmission.

Summary

Pediatric anesthetic neurotoxicity, management of intraoperative bleeding, and the effect of anesthesia on tumor growth are among the most debated and researched topics in pediatric neuroanesthesia. The lack of evidence and clinical guidelines underlines the need for further large prospective studies in this subspecialty.

Age Difference of the Relationship Between Cerebral Oxygen Saturation and Physiological Parameters in Pediatric Cardiac Surgery with Cardiopulmonary Bypass: Analysis Using the Random-Effects Model

Recently, monitoring of cerebral oxygen saturation (ScO₂) has become widespread in pediatric cardiac surgery. Our previous study reported that mean blood pressure (mBP) was the major contributor to ScO₂ throughout cardiac surgery with cardiopulmonary bypass (CPB) in children weighing under 10 kg. We speculated that this result might be attributable to incomplete cerebral autoregulation in such young children. Accordingly, our hypothesis is that the relationship between ScO₂ and the physiological parameters may change according to the growth of the children. ScO₂ was measured with an INVOS 5100C (Somanetics, Troy, MI). Random-effects analysis was employed with ScO₂ as a dependent variable, and seven physiological parameters (mBP, central venous pressure, nasopharyngeal temperature, SaO₂, hematocrit, PaCO₂, and pH) were entered as independent covariates. The analysis was performed during the pre-CPB, CPB, and post-CPB periods by dividing the patients into two groups: infants (Infant Group) and children who were more than 1 year old (Child Group). The Infant and Child Groups consisted of 28 and 21 patients. In the random-effects analysis, mBP was the major contributor to ScO₂ during CPB in both groups. During the pre-CPB period, the effect of mBP was strongest in the Infant group. However, its effect was second to that of SaO₂ in the Child Group. During the post-CPB period, SaO₂ and mBP still affected ScO₂ in the Infant group. However, the dominant contributors were unclear in the Child Group. Cerebral autoregulation may be immature in infants. In addition, it may be impaired during CPB even after 1 year of age.

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.

Neurocardiovascular coupling in congenital diaphragmatic hernia patients undergoing different types of surgical treatment

BACKGROUND

The effect of peri-operative management on the neonatal brain is largely unknown. Triggers for perioperative brain injury might be revealed by studying changes in neonatal physiology peri-operatively.

OBJECTIVE

To study neonatal pathophysiology and cerebral blood flow regulation peri-operatively using the neuro-cardiovascular graph.

DESIGN

Observational, prospective cohort study on perioperative neuromonitoring. Neonates were included between July 2018 and April 2020.

SETTING

Multicentre study in two high-volume tertiary university hospitals.

PATIENTS

Neonates with congenital diaphragmatic hernia were eligible if they received surgical treatment within the first 28 days of life. Exclusion criteria were major cardiac or chromosomal anomalies, or syndromes associated with altered cerebral perfusion or major neurodevelopmental impairment. The neonates were stratified into different groups by type of peri-operative management.

INTERVENTION

Each patient was monitored using near-infrared spectroscopy and EEG in addition to the routine peri-operative monitoring. Neurocardiovascular graphs were computed off-line.

MAIN OUTCOME MEASURES

The primary endpoint was the difference in neurocardiovascular graph connectivity in the groups over time.

RESULTS

Thirty-six patients were included. The intraoperative graph connectivity decreased in all patients operated upon in the operation room (OR) with sevoflurane-based anaesthesia ( P  < 0.001) but remained stable in all patients operated upon in the neonatal intensive care unit (NICU) with midazolam-based anaesthesia. Thoracoscopic surgery in the OR was associated with the largest median connectivity reduction (0.33 to 0.12, P  < 0.001) and a loss of baroreflex and neurovascular coupling. During open surgery in the OR, all regulation mechanisms remained intact. Open surgery in the NICU was associated with the highest neurovascular coupling values.

CONCLUSION

Neurocardiovascular graphs provided more insight into the effect of the peri-operative management on the pathophysiology of neonates undergoing surgery. The neonate's clinical condition as well as the surgical and the anaesthesiological approach affected the neonatal physiology and CBF regulation mechanisms at different levels.

TRIAL REGISTRATION

NL6972, URL: https://www.trialre-gister.nl/trial/6972 .

Diffuse correlation spectroscopy blood flow monitoring for intraventricular hemorrhage vulnerability in extremely low gestational age newborns

In premature infants with an extremely low gestational age (ELGA, < 29 weeks GA), dysregulated changes in cerebral blood flow (CBF) are among the major pathogenic factors leading to germinal matrix/intraventricular hemorrhage (GM/IVH). Continuous monitoring of CBF can guide interventions to minimize the risk of brain injury, but there are no clinically standard techniques or tools for its measurement. We report the feasibility of the continuous monitoring of CBF, including measures of autoregulation, via diffuse correlation spectroscopy (DCS) in ELGA infants using CBF variability and correlation with scalp blood flow (SBF, served as a surrogate measure of systemic perturbations). In nineteen ELGA infants (with 9 cases of GM/IVH) monitored for 6–24 h between days 2–5 of life, we found a strong correlation between CBF and SBF in severe IVH (Grade III or IV) and IVH diagnosed within 72 h of life, while CBF variability alone was not associated with IVH. The proposed method is potentially useful at the bedside for the prompt assessment of cerebral autoregulation and early identification of infants vulnerable to GM/IVH.

Transcranial ultrasound diagnostic value of hemodynamic cerebral changes in preterm infants for early-onset sepsis

BACKGROUND

Due to the limitation of blood culture diagnosis, this study sought to evaluate the cerebral hemodynamic changes by Doppler ultrasound for timely and objective diagnosis techniques in preterm infants with early onset-neonatal sepsis.

METHODS

In this retrospective study, 86 preterm infants treated at the Department of Neonatology, Renmin Hospital of Wuhan University from January 1, 2019 to March 31, 2021, were divided into the following 2 groups: (I) the early onset neonatal sepsis (EONS) group (G1, n=41); (II) the normal control group (G2, n=45). The cerebral hemodynamic changes were examined by transcranial ultrasound. Stata15.0 and SPSS26.0 software were used for the data analysis. The pair-wise comparisons of the receiver operating characteristic (ROC) curves were on the MedCalc18.2.1 software. For all the statistical analyses, P value <0.05 was considered significant.

RESULTS

Sex, birth weight, and gestational age did not differ significantly between the groups (P>0.05); the peak systolic velocity (PSV), mean velocity (MV), end diastolic velocity (EDV) (cm/s), resistivity index (RI), pulsatility index (PI) of the anterior cerebral artery (ACA), middle cerebral artery (MCA), and posterior cerebral artery (PCA) differed significantly between 2 groups (P<0.05). In relation to the diagnostic sensitivity, the area under the receiver operating characteristic (AUROC) analyses showed that compared to IL-6 (0.95, 1.00), EDV of the ACA, and PSV, EDV and MV of the MCA and PCA had a higher sensitivity than the others (AUROC: 1, all 95% CI: 1.00, 1.00). The diagnostic points of the EDV and MV of the ACA were 9.8 and 17.3 cm/s, respectively, the PSV, EDV, and MV of the MCA were 55.9, 10.9, and 20.4 cm/s, respectively, and the PSV, EDV, and MV of the PCA were 27.5, 7.5, and 9.8 cm/s, respectively.

CONCLUSIONS

The study showed that PI increases and RI decreases, MV increases, and cerebral blood flow increases in EONS. Further, the EDV and MV of the ACA and the PSV, EDV, and MV of the MCA and PCA showed higher sensitivity than IL-6.

Clinical determinants of cerebrovascular reactivity in very preterm infants during the transitional period

BACKGROUND

Preterm infants are at enhanced risk of brain injury due to altered cerebral haemodynamics during postnatal transition. This observational study aimed to assess the clinical determinants of transitional cerebrovascular reactivity and its association with intraventricular haemorrhage (IVH).

METHODS

Preterm infants <32 weeks underwent continuous monitoring of cerebral oxygenation and heart rate over the first 72 h after birth. Serial cranial and cardiac ultrasound assessments were performed to evaluate the ductal status and to diagnose IVH onset. The moving correlation coefficient between cerebral oxygenation and heart rate (TOHRx) was calculated. Linear mixed-effect models were used to analyse the impact of relevant clinical variables on TOHRx. The association between TOHRx and IVH development was also assessed.

RESULTS

Seventy-seven infants were included. A haemodynamically significant patent ductus arteriosus (hsPDA) (β = 0.044, 95% CI: 0.007-0.081) and ongoing dopamine treatment (β = 0.096, 95% CI: 0.032-0.159) were associated with increasing TOHRx, indicating impaired cerebrovascular reactivity. A significant association between TOHRx, mean arterial blood pressure (β = -0.004, 95% CI: -0.007, -0.001) and CRIB-II score (β = 0.007, 95% CI: 0.001-0.015) was also observed. TOHRx was significantly higher in infants developing high-grade IVH compared to those without IVH.

CONCLUSIONS

Dopamine treatment, low blood pressure, hsPDA and high CRIB-II are associated with impaired cerebrovascular reactivity during postnatal transition, with potential implications on IVH development.

IMPACT

The correlation coefficient between cerebral oxygenation and heart rate (TOHRx) provides a non-invasive estimation of cerebrovascular reactivity, whose failure has a potential pathogenic role in the development of IVH in preterm infants. This study shows that cerebrovascular reactivity during the transitional period improves over time and is affected by specific clinical and therapeutic factors, whose knowledge could support the development of individualized neuroprotective strategies in at-risk preterm infants. The evidence of increased TOHRx in infants developing high-grade compared to low-grade or no IVH during the transitional period further supports the role of impaired cerebrovascular reactivity in IVH pathophysiology.

Cerebral Blood Flow Autoregulation in Offspring From Experimentally Preeclamptic Rats and the Effect of Age

Preeclampsia is a hypertensive disorder of pregnancy that causes significant, long term cardiovascular effects for both the mother and offspring. A previous study demonstrated that middle cerebral arteries in offspring from an experimental rat model of preeclampsia were smaller, stiffer, and did not enlarge over the course of maturation, suggesting potential hemodynamic alterations in these offspring. Here we investigated the effect of experimental preeclampsia on cerebral blood flow autoregulation in juvenile and adult offspring that were born from normal pregnant or experimentally preeclamptic rats. Relative cerebral blood flow was measured using laser Doppler flowmetry, and cerebral blood flow autoregulation curves were constructed by raising blood pressure and controlled hemorrhage to lower blood pressure. Immunohistochemistry was used to assess middle cerebral artery size. Heart rate and blood pressure were measured in awake adult offspring using implanted radiotelemetry. Serum epinephrine was measured using enzyme-linked immunosorbent assay. Offspring from both groups showed maturation of cerebral blood flow autoregulation as offspring aged from juvenile to adulthood as demonstrated by the wider autoregulatory plateau. Experimental preeclampsia did not affect cerebral blood flow autoregulation in juvenile offspring, and it had no effect on cerebral blood flow autoregulation in adult offspring over the lower range of blood pressures. However, experimental preeclampsia caused a right shift in the upper range of blood pressures in adult offspring (compared to normal pregnant). Structurally, middle cerebral arteries from normal pregnant offspring demonstrated growth with aging, while middle cerebral arteries from experimentally preeclamptic offspring did not, and by adulthood normal pregnant offspring had significantly larger middle cerebral arteries. Middle cerebral artery lumen diameters did not significantly change as offspring aged. Serum epinephrine was elevated in juvenile experimentally preeclamptic offspring, and a greater degree of hemorrhage was required to induce hypotension, suggesting increased sympathetic activity. Finally, despite no evidence of increased sympathetic activity, adult experimentally preeclamptic offspring were found to have persistently higher heart rate. These results demonstrate a significant effect of experimental preeclampsia on the upper range of autoregulation and cerebrovascular structure in juvenile and adult offspring that could have an important influence on brain perfusion under conditions of hypo and/or hypertension.

Neonatal hemorrhage stroke and severe coagulopathy in a late preterm infant after receiving umbilical cord milking: A case report

BACKGROUND

Umbilical cord milking (UCM) is an alternative placental transfusion method for delayed umbilical cord clamping in routine obstetric practice, allowing prompt resuscitation of an infant. Thus, UCM has been adopted at some tertiary neonatal centers for preterm infants to enhance placental-to-fetal transfusion. It is not suggested for babies less than 28 wk of gestational age because it is associated with severe brain hemorrhage. For late preterm or term infants who do not require resuscitation, cord management is recommended to increase iron levels and prevent the development of iron deficiency anemia, which is associated with impaired motor development, behavioral problems, and cognitive delays. Concerns remain about whether UCM increases the incidence of intraventricular hemorrhage. However, there are very few reports of late preterm infants presenting with neonatal hemorrhage stroke (NHS) and severe coagulopathy after receiving UCM. Here, we report a case of a late preterm infant born at 34 wk of gestation. She abruptly deteriorated, exhibiting signs and symptoms of NHS and severe coagulopathy after receiving UCM on the first day of life.

CASE SUMMARY

A female preterm infant born at 34 wk of gestation received UCM after birth. She was small for her gestational age and described as vigorous with Apgar scores of 9 and 10 at one minute and five minutes of life, respectively. After hospitalization in the neonatal intensive care unit, she showed hypoglycemia and metabolic acidosis. The baby was administered glucose and sodium bicarbonate infusions. Intramuscular vitamin K1 was also used to prevent vitamin K deficiency. The baby developed umbilical cord bleeding and gastric bleeding on day 1 of life; a physical examination showed bilateral conjunctival hemorrhage, and a blood test showed thrombocytopenia, prolonged prothrombin time, prolonged activated partial thromboplastin time, low fibrinogen, raised D-dimer levels and anemia. A subsequent cranial ultrasound and computed tomography scan showed a left parenchymal brain hemorrhage with extension into the ventricular and subarachnoid spaces. The patient was diagnosed with NHS in addition to disseminated intravascular coagulation (DIC). Fresh frozen plasma (FFP) and prothrombin complex concentrate were given for coagulopathy. Red blood cell and platelet transfusions were provided for thrombocytopenia and anemia. A bolus of midazolam, intravenous calcium and phenobarbital sodium were administered to control seizures. The baby’s clinical condition improved on day 5 of life, and the baby was hospitalized for 46 d and recovered well without seizure recurrence. Our case report suggests that preterm infants who receive UCM should undergo careful clinical assessment for intracranial hemorrhage, NHS and severe coagulopathy that may develop under certain circumstances. Supportive management, such as intensive care, FFP and blood transfusion, is recommended when the development of massive NHS and associated DIC is suspected.

CONCLUSION

Our case report suggests that for late preterm infants who are small for gestational age and who receive UCM for alternative placental transfusion, neonatal health care professionals should be cautious in assessing the development of NHS and severe coagulopathy. Neonatal health care professionals should also be more cautious in assessing the complications of late preterm infants after they receive UCM.

Impact of surgery and anesthesia during early brain development: A perfect storm

Neonatal surgery and concomitant anesthesia coincide with a timeframe of rapid brain development. The speed and complexity of early brain development superimposed on immature regulatory mechanisms that include incomplete cerebral autoregulation, insufficient free radical scavenging and an immature immune response puts the brain at risk. Brain injury may have long-term consequences for multiple functional domains including cognition, learning skills, and behavior. Neurodevelopmental follow-up studies have noted mild-to-moderate deficits in children who underwent major neonatal surgery and related anesthesia. The present review evaluates neonatal surgery against the background of neurobiological processes that unfold at a pace unparalleled by any other period of human brain development. First, a structured summary of early brain development is provided in order to establish theoretical groundwork. Next, literature on brain injury and neurodevelopmental outcome after neonatal surgery is discussed. Special attention is given to recent findings of structural brain damage reported after neonatal surgery. Notably, high-quality imaging data acquired before surgery are currently lacking. Third, mechanisms of injury are interrogated taking the perspective of early brain development into account. We propose a novel disease model that constitutes a triad of inflammation, vascular immaturity, and neurotoxicity of prolonged exposure to anesthetic drugs. With each of these components exacerbating the other, this amalgam incites the perfect storm, resulting in brain injury. When examining the brain, it seems intuitive to distinguish between neonates (i.e., <60 postconceptional weeks) and more mature infants, multiple and/or prolonged anesthesia exposure and single, short surgery. This review culminates in an outline of anesthetic considerations and future directions that we believe will help move the field forward.

Protecting the brain of the micropreemie

Advances in perinatal care have seen substantial improvements in survival without disability for extremely preterm infants. Protecting the developing brain and reducing neurodevelopmental sequelae of extremely preterm birth are strategic priorities for both research and clinical care. A number of evidence-based interventions exist for neuroprotection in micropreemies, inclusive of prevention of preterm birth and multiple births with implantation of only one embryo during in vitro fertilisation, as well as antenatal care to optimize fetal wellbeing, strategies for supporting neonatal transition, and neuroprotective developmental care. Avoidance of complications that trigger ischemia and inflammation is vital for minimizing brain dysmaturation and injury, particularly of the white matter. Neurodevelopmental surveillance, early diagnosis of cerebral palsy and early intervention are essential for optimizing long-term outcomes and quality of life. Research priorities include further evaluation of putative neuroprotective agents, and investigation of common neonatal interventions in trials adequately powered to assess neurodevelopmental outcome.

The effect of head positioning on brain tissue oxygenation in preterm infants: a randomized clinical trial study

BACKGROUND

CNS injury in preterm infants is still one of the leading causes of mortality and morbidity. Routine care events might affect the perfusion and cerebral oxygenation of preterm infants. Although positioning the infant's head in a particular condition to improve brain oxygenation is included in many institutions, there is no robust clinical evidence to support this intervention's effectiveness.

OBJECTIVE

The present study aimed to determine the effect of head positioning on brain tissue oxygenation in preterm infants.

METHODS

This study is a randomized clinical trial. In the first 48 h after birth, 39 infants who met the study inclusion criteria underwent head positioning intervention. In this case, the infants were placed in the supine position, and every 2 h, the head position was changed continuously to one of six randomized modes [using random modes generated by SPSS]. During each head positioning, brain tissue oxygenation was recorded by NIRS.

RESULTS

The findings showed a significant difference in brain tissue oxygen saturation among these positions (P < 0.001). Dunn's test showed that the brain tissue oxygen saturation in the third position (head rotates 45-60 degrees from the midline to the right and the head of the bed is zero degrees) was significantly lower than the baseline (P = 0.029; Mean difference = 2.3). Also, in the third position, compared to the first position (P = 0.002; Mean difference = 1.9) and compared to the fourth position (P = 0.003; Mean difference = -2.1), and in the second position compared to the first position (P = 0.046; Mean difference = 1.3), the brain tissue oxygen saturation of the infants was lower.

CONCLUSION

Based on the results of the present study, head positioning was effective on brain tissue oxygenation in preterm infants in the first 48 h after birth; Therefore, it is recommended when possible, not to rotate the infant's head during the first 48 h after birth while the head of the bed is at 0°.