Hypothermia for newborns with hypoxic-ischemic encephalopathy

Current status and controversies in the treatment of neonatal hypoxic-ischemic encephalopathy: A review

Neonatal hypoxic-ischemic encephalopathy is a type of traumatic brain injury caused by insufficient cerebral perfusion and oxygen supply in the perinatal neonate, which can be accompanied by different types of long-term neurodevelopmental sequelae, such as cerebral palsy, learning disabilities, mental retardation and epilepsy It is one of the main causes of neonatal death and disability, and it has caused a great burden on families and society. Therefore, this article mainly reviews the latest developments in mild hypothermia therapy and related drugs for neonatal hypoxic-ischemic encephalopathy.

Relationship between EEG spectral power and dysglycemia with neurodevelopmental outcomes after neonatal encephalopathy

OBJECTIVE

We investigated how electroencephalography (EEG) quantitative measures and dysglycemia relate to neurodevelopmental outcomes following neonatal encephalopathy (NE).

METHODS

This retrospective study included 90 neonates with encephalopathy who received therapeutic hypothermia. EEG absolute spectral power was calculated during post-rewarming and 2-month follow-up. Measures of dysglycemia (hypoglycemia, hyperglycemia, and glycemic lability) and glucose variability were computed for the first 48 h of life. We evaluated the ability of EEG and glucose measures to predict neurodevelopmental outcomes at ≥ 18 months, using logistic regressions (with area under the receiver operating characteristic [AUROC] curves).

RESULTS

The post-rewarming global delta power (average all electrodes), hyperglycemia and glycemic lability predicted moderate/severe neurodevelopmental outcome separately (AUROC = 0.8, 95%CI [0.7,0.9], p < .001) and even more so when combined (AUROC = 0.9, 95%CI [0.8,0.9], p < .001). After adjusting for NE severity and magnetic resonance imaging (MRI) brain injury, only global delta power remained significantly associated with moderate/severe neurodevelopmental outcome (odds ratio [OR] = 0.9, 95%CI [0.8,1.0], p = .04), gross motor delay (OR = 0.9, 95%CI [0.8,1.0], p = .04), global developmental delay (OR = 0.9, 95%CI [0.8,1.0], p = .04), and auditory deficits (OR = 0.9, 95%CI [0.8,1.0], p = .03).

CONCLUSIONS

In NE, global delta power post-rewarming was predictive of outcomes at ≥ 18 months.

SIGNIFICANCE

EEG markers post-rewarming can aid prediction of neurodevelopmental outcomes following NE.

Practice Variations for Therapeutic Hypothermia in Neonates with Hypoxic-ischemic Encephalopathy: An International Survey

OBJECTIVE

To evaluate variations in management of therapeutic hypothermia (TH) for neonatal hypoxic-ischemic encephalopathy (HIE) among international clinical sites and to identify areas for harmonization.

STUDY DESIGN

An electronic survey was sent to Children's Hospitals Neonatal Consortium site sponsors, Canadian Neonatal Network site investigators, members of the Newborn Brain Society, and American Academy of Pediatrics Neonatology chiefs.

RESULTS

One hundred five sites responded, with most from high-income regions (n = 95). Groupings were adapted from the United Nations regional groups: US (n = 52 sites); Canada (n = 20); Western Europe and other states excluding Canada and US Group (WEOG, n = 18); and non-WEOG (central and eastern Europe, Asia, Africa, Latin America, and Caribbean, n = 15). Regional variations were seen in the eligibility criteria for TH, such as the minimum gestational age, grading of HIE severity, use of electroencephalography, and the frequency of providing TH for mild HIE. Active TH during transport varied among regions and was less likely in smaller volume sites. Amplitude-integrated electroencephalogram and/or continuous electroencephalogram to determine eligibility for TH was used by most sites in WEOG and non-WEOG but infrequently by the US and Canada Groups. For sedation during TH, morphine was most frequently used as first choice but there was relatively high (33%) use of dexmedetomidine in the US Group. Timing of brain magnetic resonance imaging and neurodevelopmental follow-up were variable. Neurodevelopmental follow occurred earlier and more frequently, although for a shorter duration, in the non-WEOG.

CONCLUSIONS

We found significant variations in practices for TH for HIE across regions internationally. Future guidelines should incorporate resource availability in a global perspective.

Eucapnic pH coupled with arterial cord pH improves hypoxic-ischemic encephalopathy prediction

OBJECTIVE

To consider the classical use of "pH < 7.0 and/or a base deficiency ≥12 mmol/L" as markers of the risk of neonatal hypoxic-ischemic encephalopathy (HIE), recalling various criticisms of the use of these markers in favor of that of neonatal eucapnic pH, which appears to be a better marker of this risk.

METHODS

Fifty-five cases of acidemia with pH < 7.00 were collected from a cohort from the Nice University Hospital with eight cases of HIE. We compared the receiver operating characteristics curves established from the positive likelihood ratio (+LR) for each case of: umbilical cord artery pH (pHa), neonatal eucapnic pH (pH euc-n) in isolation (not matched to pHa), and matched pHa to its own pH euc-n.

RESULTS

The areas under the curve (AUC) are identical for pHa and pH euc-n, but AUC for the matched pair pHa-pH euc-n appears superior but non-significant because of the small number in our cohort. However, using the bootstrap method, the partial AUC for a sensitivity greater than 75% indicates the significant superiority (P < 0.01) of the matched pair pHa-pH euc-n approach.

CONCLUSION

The originality of this study lies in the use of two methodologic approaches: (1) standardized partial analysis of the AUCs of the pHa curve and that of pHa matched to its own pH euc-n, and (2) bootstrap statistical technique, that allowed us to conclude (P < 0.01) that the combined use of pH measured at the cord coupled with its eucapnic correction is better for diagnosing metabolic acidosis and best predicting the risk of HIE.

Risk Factors for Term-Born Spastic Diplegic Cerebral Palsy: A Case-Control Study

BACKGROUND

To identify if a predetermined set of potential risk factors are associated with spastic diplegic cerebral palsy (SDCP) in term-born children.

METHODS

This is a case-control study with cases (n = 134) extracted from the Canadian Cerebral Palsy Registry (CCPR) and controls (n = 1950) from the Alberta Pregnancy Outcomes and Nutrition (APrON) study. Our primary variable was the SDCP phenotype in term-born children. Possible risk factors were selected a priori and include extreme maternal age (<19 or >35 years), pregnancy complications, maternal disease, substance use, perinatal infection, mode of delivery, perinatal adversity (i.e., neonatal encephalopathy presumably on the basis of intrapartum hypoxia-ischemia), sex, and birth weight. Multivariable analyses were used to calculate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Multivariable analysis revealed associations between term-born SDCP and pregnancy complications (OR = 4.73; 95% CI = 1.91 to 10.56), maternal disease (OR = 2.52; 95% CI = 1.57 to 3.93), substance use (OR = 3.11; 95% CI = 2.10 to 4.55), perinatal infection (OR = 2.72; 95% CI 1.32 to 5.10), Caesarean section (OR = 2.35; 95% CI = 1.62 to 3.40), and perinatal adversity (OR = 2.91; 95% CI = 1.94 to 4.50). Multiple regression analysis revealed associations between SDCP and pregnancy complications (OR = 3.28; 95% CI 1.20 to 8.15), maternal disease (OR = 2.52; 95% CI 1.50 to 4.12), substance use (OR = 3.59; 95% CI 2.37 to 5.40), perinatal infection (OR = 3.78, 95% CI 1.71 to 7.72), Caesarean section (OR = 2.72; 95% CI 1.82 to 4.03), and perinatal adversity (OR = 4.16; 95% CI 2.67 to 6.70).

INTERPRETATION

Antenatal (pregnancy complications, maternal disease, substance use) and perinatal (infections, Caesarean section, and perinatal adversity) risk factors are associated with an increased risk of SDCP in term-born children, suggesting variable interactions between risk factors to provide a clinicopathologic framework that is different from SDCP observed in preterm-born children.

Exposure to Maternal Diabetes during Pregnancy Is Associated with Aggravated Short-Term Neonatal and Neurological Outcomes following Perinatal Hypoxic-Ischemic Encephalopathy

OBJECTIVE

Infants of diabetic mothers (IDM) are at higher risk of perinatal morbidities and glycemic instability, but the impact of maternal diabetes on neonatal and neurological short-term outcomes of neonates with hypoxic-ischemic encephalopathy (HIE) remains poorly described. Our objective was to determine the impact of maternal diabetes on neonatal and neurological short-term outcomes following neonatal HIE.

STUDY DESIGN

This was a retrospective single-center study including 102 term neonates with HIE who received therapeutic hypothermia (TH) treatment between 2013 and 2020. Multiple regression analysis was used to assess the relationship between the presence of maternal diabetes and short-term outcomes.

RESULTS

Neonates with HIE and maternal diabetes exposure had a significantly lower gestational age at birth (38.6 vs. 39.7 weeks of gestation, p = 0.005) and a significantly higher mean birth weight (3,588 ± 752 vs. 3,214 ± 514 g, p = 0.012). IDM with HIE were ventilated for longer duration (8 vs. 4 days, p = 0.0047) and had a longer neonatal intensive care unit (NICU) stay (18 vs. 11 days, p = 0.0483) as well as took longer time to reach full oral feed (15 vs. 7 days, p = 0.0432) compared with neonates of nondiabetic mother. Maternal diabetes was also associated with an increased risk of death or abnormal neurological examination at discharge in neonates with HIE (odds ratio: 6.41 [1.54-26.32]).

CONCLUSION

In neonates with HIE, maternal diabetes is associated with an increased risk of death or short-term neonatal morbidities, such as longer duration of ventilation, prolonged neonatal stay, greater need for tube feeding, and being discharged with an abnormal neurological examination. Strategies to prevent, reduce, or better control maternal diabetes during pregnancy should be prioritized to minimize complications after perinatal asphyxia.

KEY POINTS

· Maternal DB is associated with unfavorable outcomes.. · IDM have longer ventilatory support and tube feeding.. · IDM have higher risk of abnormal neurological examination..

Regional variability in therapeutic hypothermia eligibility criteria for neonatal hypoxic-ischemic encephalopathy

Early induced therapeutic hypothermia represents the cornerstone treatment in neonates with probable hypoxic-ischemic encephalopathy. The selection of patients for treatment usually involves meeting criteria indicating evidence of perinatal hypoxia-ischemia and the presence of moderate or severe encephalopathy. In this review, we highlight the variability that exists between some of the different regional and national eligibility guidelines. Determining the potential presence of perinatal hypoxia-ischemia may require either one, two or three signs amongst history of acute perinatal event, prolonged resuscitation at delivery, abnormal blood gases and low Apgar score, with a range of cutoff values. Clinical neurological exams often define the severity of encephalopathy differently, with varying number of domains required for determining eligibility and blurred interpretation of findings assigned to different severity grades in different systems. The role of early electrophysiological assessment is weighted differently. A clinical implication is that infants may receive different care depending on the location in which they are born. This could also impact epidemiological data, as inference of rates of moderate-severe encephalopathy based on therapeutic hypothermia rates are misleading and influenced by different eligibility methods used. We would advocate that a universally endorsed single severity staging of encephalopathy is vital for standardizing management and neonatal outcome. IMPACT: Variability exists between regional and national therapeutic hypothermia eligibility guidelines for neonates with probable hypoxic-ischemic encephalopathy. Differences are common in both criteria indicating perinatal hypoxia-ischemia and criteria defining moderate or severe encephalopathy. The role of early electrophysiological assessment is also weighted unequally. This reflects in different individual care and impacts research data. A universally endorsed single severity staging of encephalopathy would be crucial for standardizing management.

Umbilical artery eucapnic pH to assess fetal well-being

BACKGROUND

Umbilical artery gas results help obstetricians assess fetal well-being during labor and guide screening decisions on eligibility for therapeutic hypothermia (ie, whole-body or head cooling). The accuracy of results, especially for the base deficit on arterial cord gas analysis, in predicting brain injury is questioned. A novel biomarker specifically calculated for fetal acid-base physiology and response to asphyxia-neonatal eucapnic pH as a marker of neonatal metabolic acidosis-has the potential to be an accurate predictor of hypoxic-ischemic encephalopathy.

OBJECTIVE

We aimed to compare false-negative rates of hypoxic-ischemic encephalopathy for umbilical artery pH, base deficit, and neonatal eucapnic pH in assessing fetal acid-base balance as a marker of fetal well-being and predicting acute brain injury.

STUDY DESIGN

This is a retrospective single-center cohort study of newborns ≥ 35 weeks of gestation diagnosed with hypoxic-ischemic encephalopathy. We compared false-negative rates for any grade of hypoxic-ischemic encephalopathy using unilateral paired chi-square statistical analysis based on cutoff values for umbilical artery pH ≤7.00, base deficit ≥16 mmol/L, base deficit ≥12 mmol/L and neonatal eucapnic pH ≤7.14. We performed an analysis of variance between umbilical artery pH, base deficit, and neonatal eucapnic pH for each hypoxic-ischemic encephalopathy grade.

RESULTS

We included 113 newborns. False-negative rate for hypoxic-ischemic encephalopathy was significantly higher for base deficit <16 mmol/L (n=78/113; 69.0%) than <12 mmol/L (n=46/113; 40.7%), pH >7.00 (n=41/113; 36.3%), or neonatal eucpanic pH >7.14 (n=35/113; 31.0%) (P<.0001). All true-positive cases were identified using only umbilical artery pH and neonatal eucapnic pH. Base deficit ≥16 or ≥12 mmol/L did not add any value in identifying newborns with hypoxic-ischemic encephalopathy when using umbilical artery pH and neonatal eucapnic pH. No association emerged between any marker and hypoxic-ischemic encephalopathy severity grading.

CONCLUSION

Our findings support the accuracy of neonatal eucapnic pH to assess fetal well-being during labor and to improve predictive performance for acute brain injury. Neonatal eucpanic pH, in addition to umbilical artery pH, may be a viable alternative in identifying newborns at risk for hypoxic-ischemic encephalopathy.

Determining the Effect of Birth Weight on Therapeutic Hypothermia in Neonates with Hypoxic-Ischemic Encephalopathy

OBJECTIVE

We examine the effect of birth weight (BW) for gestational age (GA) on the temperatures reached during the treatment of neonatal hypoxic-ischemic encephalopathy (HIE) with therapeutic hypothermia (TH).

STUDY DESIGN

Retrospective data of 1,736 neonates with HIE who received TH were extracted from the Canadian Neonatal Network database for neonates admitted from 2010 to 2017. Neonates were stratified into three BW groups: small for GA < 10th centile, large for GA > 90th centile, and according to GA 10th to 89th centile at a given gestation using Canadian population data norms.

RESULTS

There was no significant difference in the lowest temperature reached, the likelihood of overshooting temperatures < 32.5°C during TH, or the change of encephalopathy stages among the three groups.

CONCLUSION

BW for GA did not appear to influence the temperatures neonates reached during hypothermia or encephalopathy stage following TH.

KEY POINT

· Therapeutic hypothermia is well tolerated irrespective of weight for age. · SGA infants achieved and maintained target temperature similar to AGA and LGA babies. · Change in the Sarnat stage after hypothermia was similar across all birth weight groups.

Risk Factors and Outcomes for Cerebral Palsy With Hypoxic-Ischemic Brain Injury Patterns Without Documented Neonatal Encephalopathy

BACKGROUND AND OBJECTIVES

Perinatal hypoxic-ischemic brain injury is a leading cause of term-born cerebral palsy, the most common lifelong physical disability. Diagnosis is commonly made in the neonatal period by the combination of neonatal encephalopathy (NE) and typical neuroimaging findings. However, children without a history of neonatal encephalopathy may present later in childhood with motor disability and neuroimaging findings consistent with perinatal hypoxic-ischemic injury. We sought to determine the prevalence of such presentations using the retrospective viewpoint of a large multiregional cerebral palsy registry.

METHODS

Patient cases were extracted from the Canadian Cerebral Palsy Registry with gestational age >36 weeks, an MRI pattern consistent with hypoxic-ischemic injury (HII, acute total, partial prolonged, or combined), and an absence of postnatal cause for HII. Documentation of NE was noted. Maternal-fetal risk factors, labor and delivery, neonatal course, and clinical outcome were extracted. Comparisons were performed using χ2 tests and multivariable logistic regression with multiple imputation. Propensity scores were used to assess for bias.

RESULTS

Of the 170 children with MRI findings typical for HII, 140 (82.4%, 95% confidence interval [CI] 75.7%-87.7%) had documented NE and 29 (17.0%, 95% CI 11.7%-23.6%) did not. The group without NE had more abnormalities of amniotic fluid volume (odds ratio [OR] 15.8, 95% CI 1.2-835), had fetal growth restriction (OR 4.7, 95% CI 1.0-19.9), had less resuscitation (OR 0.03, 95% CI 0.007-0.08), had higher 5-minute Apgar scores (OR 2.2, 95% CI 1.6-3.0), were less likely to have neonatal seizures (OR 0.004, 95% CI 0.00009-0.03), and did not receive therapeutic hypothermia. MRI was performed at a median 1.1 months (interquartile range [IQR] 0.67-12.8 months) for those with NE and 12.2 months (IQR 6.6-25.9) for those without (p = 0.011). Patterns of injury on MRI were seen in similar proportions. Hemiplegia was more common in those without documented NE (OR 5.1, 95% CI 1.5-16.1); rates of preserved ambulatory function were similar.

DISCUSSION

Approximately one-sixth of term-born children with an eventual diagnosis of cerebral palsy and MRI findings consistent with perinatal hypoxic-ischemic brain injury do not have documented neonatal encephalopathy, which was associated with abnormalities of fetal growth and amniotic fluid volume, and a less complex neonatal course. Long-term outcomes seem comparable with their peers with encephalopathy. The absence of documented neonatal encephalopathy does not exclude perinatal hypoxic-ischemic injury, which may have occurred antenatally and must be carefully evaluated with MRI.

Is it time to end the use of base deficit for fetal well-being assessment?

Authors have expressed reservations regarding the use of base deficit measured in umbilical artery blood samples to assess fetal well-being during the course of labor and to predict neonatal neurologic morbidity. Despite its integration into clinical practice for more than 50 years, obstetricians and maternal-fetal medicine specialists may not realize that this marker has significant limitations in accurately identifying neonatal metabolic acidosis as a proxy for fetal well-being. In brief, there are 2 large families of base deficit, namely whole blood and extracellular fluid. Both rely on equations that use normal adult acid-base characteristics (pH 7.40 and partial CO2 pressure of 40 mm Hg) that overlook the specificity of the normal in utero acid-base status of pH 7.27 and partial CO2 pressure of 54 mm Hg. In addition, it ignores the unique characteristic of the in utero fetal response to acute hypoxia. The dependence on placental circulation for CO2 elimination may lead to extremely high values (up to 130 to 150 mm Hg) during hypoxic events, a phenomenon that is absent in adults with acute metabolic acidosis who can hyperventilate. The dispute over if to include a correction for high partial CO2 pressure in the bicarbonate estimation, as presented in the Great Trans-Atlantic Debates, remains unresolved. The key constants computed for adult acid-base physiology in the current base deficit algorithms, without accounting for the impact of high partial CO2 pressure or other fetal characteristics of buffering capacity (eg, differences in body water content composition, plasma protein, and hemoglobin attributes), may lead to an overestimation of metabolic acidosis, especially in newborns who are experiencing hypercarbia during the early stages of the hypoxic response. These unrecognized limitations impact the base deficit results and may mislead clinicians on fetal well-being assessments when discussing the management of fetal heart rate monitoring and neonatal outcomes. Based on our arguments, we believe that it is prudent to consider an alternative to base deficit for drawing conclusions regarding fetal well-being during the course of birth management. We propose a marker specifically related to the newborn acid-base physiology--the neonatal eucapnic pH correction. This marker can be added to arterial cord blood gas analysis, and we have described how to interpret it as a marker of neonatal metabolic acidosis.

An Assessment of Physical and N6-Cyclohexyladenosine-Induced Hypothermia in Rodent Distal Focal Ischemic Stroke

Therapeutic hypothermia (TH) mitigates damage in ischemic stroke models. However, safer and easier TH methods (e.g., pharmacological) are needed to circumvent physical cooling complications. This study evaluated systemic and pharmacologically induced TH using the adenosine A1 receptor agonist, N6-cyclohexyladenosine (CHA), with control groups in male Sprague-Dawley rats. CHA was administered intraperitoneally 10 minutes following a 2-hour intraluminal middle cerebral artery occlusion. We used a 1.5 mg/kg induction dose, followed by three 1.0 mg/kg doses every 6 hours for a total of 4 doses, causing 20-24 hours of hypothermia. Animals assigned to physical hypothermia and CHA-hypothermia had similar induction rates and nadir temperatures, but forced cooling lasted ∼6 hours longer compared with CHA-treated animals. The divergence is likely attributable to individual differences in CHA metabolism, which led to varied durations at nadir, whereas physical hypothermia was better regulated. Physical hypothermia significantly reduced infarction (primary endpoint) on day 7 (mean reduction of 36.8 mm3 or 39% reduction; p = 0.021 vs. normothermic animals; Cohen's d = 0.75), whereas CHA-induced hypothermia did not (p = 0.33). Similarly, physical cooling improved neurological function (physical hypothermia median = 0, physical normothermia median = 2; p = 0.008) and CHA-induced cooling did not (p > 0.99). Our findings demonstrate that forced cooling was neuroprotective compared with controls, but prolonged CHA-induced cooling was not neuroprotective.

Altered resting-state functional connectivity in newborns with hypoxic ischemic encephalopathy assessed using high-density functional near-infrared spectroscopy

Hypoxic-ischemic encephalopathy (HIE) results from a lack of oxygen to the brain during the perinatal period. HIE can lead to mortality and various acute and long-term morbidities. Improved bedside monitoring methods are needed to identify biomarkers of brain health. Functional near-infrared spectroscopy (fNIRS) can assess resting-state functional connectivity (RSFC) at the bedside. We acquired resting-state fNIRS data from 21 neonates with HIE (postmenstrual age [PMA] = 39.96), in 19 neonates the scans were acquired post-therapeutic hypothermia (TH), and from 20 term-born healthy newborns (PMA = 39.93). Twelve HIE neonates also underwent resting-state functional magnetic resonance imaging (fMRI) post-TH. RSFC was calculated as correlation coefficients amongst the time courses for fNIRS and fMRI data, respectively. The fNIRS and fMRI RSFC maps were comparable. RSFC patterns were then measured with graph theory metrics and compared between HIE infants and healthy controls. HIE newborns showed significantly increased clustering coefficients, network efficiency and modularity compared to controls. Using a support vector machine algorithm, RSFC features demonstrated good performance in classifying the HIE and healthy newborns in separate groups. Our results indicate the utility of fNIRS-connectivity patterns as potential biomarkers for HIE and fNIRS as a new bedside tool for newborns with HIE.

MicroRNA-124 negatively regulates STAT3 to alleviate hypoxic-ischemic brain damage by inhibiting oxidative stress

MicroRNA-124 (miR-124) is implicated in various neurological diseases; however, its significance in hypoxic-ischaemic brain damage (HIBD) remains unclear. This study aimed to elucidate the underlying pathophysiological mechanisms of miR-124 in HIBD. In our study performed on oxygen-glucose deprivation followed by reperfusion (OGD)/R-induced primary cortical neurons, a substantial reduction in miR-124 was observed. Furthermore, the upregulation of miR-124 significantly mitigated oxidative stress, apoptosis, and mitochondrial impairment. We demonstrated that miR-124 interacts with the signal transducer and activator of transcription 3 (STAT3) to exert its biological function using the dual-luciferase reporter gene assay. As the duration of OGD increased, miR-124 exhibited a negative correlation with STAT3. STAT3 overexpression notably attenuated the protective effects of miR-124 mimics, while knockdown of STAT3 reversed the adverse effects of the miR-124 inhibitor. Subsequently, we conducted an HIBD model in rats. In vivo experiments, miR-124 overexpression attenuated cerebral infarction volume, cerebral edema, apoptosis, oxidative stress, and improved neurological function recovery in HIBD rats. In summary, the neuroprotective effects of the miR-124/STAT3 axis were confirmed in the HIBD model. MiR-124 may serve as a potential biomarker with significant therapeutic implications for HIBD.

Biochemical profiles and organ dysfunction in neonates with hypoxic-ischemic encephalopathy post-hoc analysis of the THIN trial

BACKGROUND

Therapeutic hypothermia for infants with moderate to severe hypoxic-ischemic encephalopathy is well established as standard of care in high-income countries. Trials from low- and middle-income countries have shown contradictory results, and variations in the level of intensive care provided may partly explain these differences. We wished to evaluate biochemical profiles and clinical markers of organ dysfunction in cooled and non-cooled infants with moderate/severe hypoxic-ischemic encephalopathy.

METHODS

This secondary analysis of the THIN (Therapeutic Hypothermia in India) study, a single center randomized controlled trial, included 50 infants with moderate to severe hypoxic-ischemic encephalopathy randomized to therapeutic hypothermia (n = 25) or standard care with normothermia (n = 25) between September 2013 and October 2015. Data were collected prospectively and compared by randomization groups. Main outcomes were metabolic acidosis, coagulopathies, renal function, and supportive treatments during the intervention.

RESULTS

Cooled infants had lower pH than non-cooled infants at 6-12 h (median (IQR) 7.28 (7.20-7.32) vs 7.36 (7.31-7.40), respectively, p = 0.003) and 12-24 h (median (IQR) 7.30 (7.24-7.35) vs 7.41 (7.37-7.43), respectively, p < 0.001). Thrombocytopenia (< 100 000) was, though not statistically significant, twice as common in cooled compared to non-cooled infants (4/25 (16%) and 2/25 (8%), respectively, p = 0.67). No significant difference was found in the use of vasopressors (14/25 (56%) and 17/25 (68%), p = 0.38), intravenous bicarbonate (5/25 (20%) and 3/25 (12%), p = 0.70) or treatment with fresh frozen plasma (10/25 (40%) and 8/25 (32%), p = 0.56)) in cooled and non-cooled infants, respectively. Urine output < 1 ml/kg/h was less common in cooled infants compared to non-cooled infants at 0-24 h (7/25 (28%) vs. 16/23 (70%) respectively, p = 0.004).

CONCLUSIONS

This post hoc analysis of the THIN study support that cooling of infants with hypoxic-ischemic encephalopathy in a level III neonatal intensive care unit in India was safe. Cooled infants had slightly lower pH, but better renal function during the first day compared to non-cooled infants. More research is needed to identify the necessary level of intensive care during cooling to guide further implementation of this neuroprotective treatment in low-resource settings.

TRIAL REGISTRATION

Data from this article was collected during the THIN-study (Therapeutic Hypothermia in India; ref. CTRI/2013/05/003693 Clinical Trials Registry - India).

Acute seizure activity in neonatal inflammation-sensitized hypoxia-ischemia in mice

OBJECTIVE

To examine acute seizure activity and neuronal damage in a neonatal mouse model of inflammation-sensitized hypoxic-ischemic (IS-HI) brain injury utilizing continuous electroencephalography (cEEG) and neurohistology.

METHODS

Neonatal mice were exposed to either IS-HI with Escherichia coli lipopolysaccharide (LPS) or HI alone on postnatal (p) day 10 using unilateral carotid artery ligation followed by global hypoxia (n = 10 [5 female, 5 male] for IS-HI, n = 12 [5 female, 7 male] for HI alone). Video cEEG was recorded for the duration of the experiment and analyzed for acute seizure activity and behavior. Brain tissue was stained and scored based on the degree of neuronal injury in the hippocampus, cortex, and thalamus.

RESULTS

There was no significant difference in acute seizure activity among mice exposed to IS-HI compared to HI with regards to seizure duration (mean = 63 ± 6 seconds for HI vs mean 62 ± 5 seconds for IS-HI, p = 0.57) nor EEG background activity. Mice exposed to IS-HI had significantly more severe neural tissue damage at p30 as measured by neuropathologic scores (mean = 8 ± 1 vs 23 ± 3, p < 0.0001).

INTERPRETATION

In a neonatal mouse model of IS-HI, there was no significant difference in acute seizure activity among mice exposed to IS-HI compared to HI. Mice exposed to IS-HI did show more severe neuropathologic damage at a later age, which may indicate the presence of chronic inflammatory mechanisms of brain injury distinct from acute seizure activity.

An observational, multicenter, registry-based cohort study of Turkish Neonatal Society in neonates with Hypoxic ischemic encephalopathy

BACKGROUND

Hypoxic ischemic encephalopathy (HIE) is a significant cause of mortality and short- and long-term morbidities. Therapeutic hypothermia (TH) has been shown to be the standard care for HIE of infants ≥36 weeks gestational age (GA), as it has been demonstrated to reduce the rates of mortality, and adverse neurodevelopmental outcomes. This study aims to determine the incidence of HIE in our country, to assess the TH management in infants with HIE, and present short-term outcomes of these infants.

METHODS

The Turkish Hypoxic Ischemic Encephalopathy Online Registry database was established for this multicenter, prospective, observational, nationally-based cohort study to evaluate the data of infants born at ≥34 weeks GA who displayed evidence of neonatal encephalopathy (NE) between March, 2020 and April 2022.

RESULTS

The incidence of HIE among infants born at ≥36 weeks GA (n = 965) was 2.13 per 1000 live births (517:242440), and accounting for 1.55% (965:62062) of all neonatal intensive care unit admissions. The rates of mild, moderate and severe HİE were 25.5% (n = 246), 58.9% (n = 568), and 15.6% (n = 151), respectively. Infants with severe HIE had higher rates of abnormal magnetic resonance imaging (MRI) findings, and mortality (p<0.001). No significant difference in mortality and abnormal MRI results was found according to the time of TH initiation (<3 h, 3-6 h and >6 h) (p>0.05). TH was administered to 85 (34.5%) infants with mild HIE, and of those born of 34-35 weeks of GA, 67.4% (n = 31) received TH. A total of 58 (6%) deaths were reported with a higher mortality rate in infants born at 34-35 weeks of GA (OR 3.941, 95% Cl 1.446-10.7422, p = 0.007).

CONCLUSION

The incidence of HIE remained similar over time with a reduction in mortality rate. The timing of TH initiation, whether <3 or 3-6 h, did not result in lower occurrences of brain lesions on MRI or mortality. An increasing number of infants with mild HIE and late preterm infants with HIE are receiving TH; however, the indications for TH require further clarification. Longer follow-up studies are necessary for this vulnerable population.

An Exploratory Analysis of Gastrointestinal Morbidities and Feeding Outcomes Associated with Neonatal Hypoxic-Ischemic Encephalopathy With or Without Hypothermia Therapy

This study investigates the clinical profile and predictors of gastrointestinal/hepatic morbidities and feeding outcomes among neonates with hypoxic-ischemic encephalopathy (HIE). A single-center retrospective chart review of consecutive neonates >35 weeks of gestation admitted with a diagnosis of HIE between January 1, 2015, and December 31, 2020, and treated with therapeutic hypothermia, if met the institutional eligibility criteria. Outcomes assessed included necrotizing enterocolitis (NEC), conjugated hyperbilirubinemia, hepatic dysfunction, assisted feeding at discharge, and time to reach full enteral and oral feeds. Among 240 eligible neonates (gestational age 38.7 [1.7] weeks, birth weight 3279 [551] g), 148 (62%) received hypothermia therapy, and 7 (3%) and 5 (2%) were diagnosed with stage 1 NEC and stage 2-3 NEC, respectively. Twenty-nine (12%) were discharged home with a gastrostomy/gavage tube, conjugated hyperbilirubinemia (first week 22 [9%], at discharge 19 [8%]), and hepatic dysfunction (74 [31%]). Time to reach full oral feeds was significantly longer in hypothermic neonates compared with neonates who did not receive hypothermia (9 [7-12] days vs. 4.5 [3-9] days, p < 0.0001). Factors significantly associated with NEC were renal failure (odds ratio [OR] 9.24, 95% confidence interval [CI] 2.7-33), hepatic dysfunction (OR 5.69, 95% CI 1.6-26), and thrombocytopenia (OR 3.6, 95% CI 1.1-12), but no significant association with hypothermia, severity of brain injury, or stage of encephalopathy. Transient conjugated hyperbilirubinemia, hepatic dysfunction within first week of life, and need for assistive feeding are more common than NEC in HIE. Risk of NEC was associated with the severity of end-organ dysfunction in the first week of life, rather than severity of brain injury and hypothermia therapy per se.

Subcortical brain volumes in neonatal hypoxic-ischemic encephalopathy

BACKGROUND

Despite treatment with therapeutic hypothermia, hypoxic-ischemic encephalopathy (HIE) is associated with adverse developmental outcomes, suggesting the involvement of subcortical structures including the thalamus and basal ganglia, which may be vulnerable to perinatal asphyxia, particularly during the acute period. The aims were: (1) to examine subcortical macrostructure in neonates with HIE compared to age- and sex-matched healthy neonates within the first week of life; (2) to determine whether subcortical brain volumes are associated with HIE severity.

METHODS

Neonates (n = 56; HIE: n = 28; Healthy newborns from the Developing Human Connectome Project: n = 28) were scanned with MRI within the first week of life. Subcortical volumes were automatically extracted from T1-weighted images. General linear models assessed between-group differences in subcortical volumes, adjusting for sex, gestational age, postmenstrual age, and total cerebral volumes. Within-group analyses evaluated the association between subcortical volumes and HIE severity.

RESULTS

Neonates with HIE had smaller bilateral thalamic, basal ganglia and right hippocampal and cerebellar volumes compared to controls (all, p < 0.02). Within the HIE group, mild HIE severity was associated with smaller volumes of the left and right basal ganglia (both, p < 0.007) and the left hippocampus and thalamus (both, p < 0.04).

CONCLUSIONS

Findings suggest that, despite advances in neonatal care, HIE is associated with significant alterations in subcortical brain macrostructure.

IMPACT

Compared to their healthy counterparts, infants with HIE demonstrate significant alterations in subcortical brain macrostructure on MRI acquired as early as 4 days after birth. Smaller subcortical volumes impacting sensory and motor regions, including the thalamus, basal ganglia, and cerebellum, were seen in infants with HIE. Mild and moderate HIE were associated with smaller subcortical volumes.

Advances in Therapies to Treat Neonatal Hypoxic-Ischemic Encephalopathy

Neonatal hypoxic-ischemic encephalopathy (HIE) is a condition that results in brain damage in newborns due to insufficient blood and oxygen supply during or after birth. HIE is a major cause of neurological disability and mortality in newborns, with over one million neonatal deaths occurring annually worldwide. The severity of brain injury and the outcome of HIE depend on several factors, including the cause of oxygen deprivation, brain maturity, regional blood flow, and maternal health conditions. HIE is classified into mild, moderate, and severe categories based on the extent of brain damage and resulting neurological issues. The pathophysiology of HIE involves different phases, including the primary phase, latent phase, secondary phase, and tertiary phase. The primary and secondary phases are characterized by episodes of energy and cell metabolism failures, increased cytotoxicity and apoptosis, and activated microglia and inflammation in the brain. A tertiary phase occurs if the brain injury persists, characterized by reduced neural plasticity and neuronal loss. Understanding the cellular and molecular aspects of the different phases of HIE is crucial for developing new interventions and therapeutics. This review aims to discuss the pathophysiology of HIE, therapeutic hypothermia (TH), the only approved therapy for HIE, ongoing developments of adjuvants for TH, and potential future drugs for HIE.

Quality improvement sustainability to decrease utilization drift for therapeutic hypothermia in the NICU

OBJECTIVES

Therapeutic hypothermia (TH) is now standard of care for the neuroprotection of patients with moderate to severe hypoxic-ischemic encephalopathy (HIE). TH misuse results in increased medical complication rates and high health care resource utilization. Quality improvement (QI) methodology can address drift from clinical guidelines. Assessment of sustainability of any intervention over time is an integral part of the QI methodology.

METHODS

Our prior QI intervention improved medical documentation using an electronic medical record-smart phrase (EMR-SP) and demonstrated special cause variation. This study serves as Epoch 3 and investigates the sustainability of our QI methods to decrease TH misuse.

RESULTS

A total of 64 patients met the diagnostic criteria for HIE. Over the study period, 50 patients were treated with TH, and 33 cases (66%) used TH appropriately. The number of appropriate TH cases between cases of misuse increased to an average of 9 in Epoch 3 from 1.9 in Epoch 2. Of the 50 cases, 34 (68%) had EMR-SP documentation included. Length of stay and TH complication rates did not vary between cases of TH misuse and appropriate TH use.

CONCLUSIONS

Our study confirmed a sustained decrease in TH misuse, despite inconsistent use of EMR-SP. We speculate that culture change involving increased awareness of guidelines through education may have contributed more to a lasting change.

Comparing Three Methods of Therapeutic Hypothermia Among Transported Neonates with Hypoxic-Ischemic Encephalopathy

Hypoxic-ischemic encephalopathy (HIE) and associated multiorgan injury are significant causes of morbidity and mortality in term and near-term neonates. Therapeutic hypothermia (TH) is the current standard of care for neuroprotection in neonates with HIE. In our experience, the majority of babies born with HIE were found in nontertiary care facilities in our region, where effective methods of cooling during transport to tertiary care centers are desirable. Most centers initiate passive TH at referral hospitals, while active cooling is typically initiated during transport. The objective of this study was to evaluate the effectiveness of three methods of cooling during transport of neonates with HIE in southern Alberta. In this prospective cohort study, 186 neonates with HIE were transported between January 2013 and December 2021. Among the 186 neonates, 47 were passively cooled, 36 actively cooled with gel packs, and 103 cooled with a servo-controlled cooling device. The clinical characteristics were comparable for the three groups, with no difference in adverse events. Fifteen neonates (8%) died and 54 neonates (29%) suffered radiologically determined brain injury. Servo-controlled cooling was found to be superior to other methods in maintaining a target temperature without significant fluctuation during transport and with temperature in the target range on arrival at tertiary care facilities. The rate of overcooling was also lower in the servo-controlled group compared with other groups. There were no statistically significant differences between the groups in relation to mortality and brain MRI changes associated with HIE. Adjusting for GA, 10-minute Apgar score, base excess, HIE stage, and need for intubation during transport, passive cooling increased the odds of temperature fluctuation outside the range by 12-fold and gel pack cooling by 13-fold compared with servo-controlled cooling. The use of servo-controlled TH devices should be the preferred practice wherever feasible. (REB17-1334_REN3).

Head cooling wrap could suppress the elevation of core temperature after cardiac surgery during forced-air warming in a pediatric intensive care unit: a randomized clinical trial

PURPOSE

The main aim of the current trial was to explore our hypothesis that cooling head wraps lower the core temperature more effectively than ice packs on the head during forced-air warming after pediatric cardiac surgeries.

METHODS

This study was a single-center Randomized Controlled Trial. Participants were children with a weight ≤ 10 kg and hyperthermia during forced-air warming after cardiac surgeries. When the core temperature reached 37.5 °C, ice packs on the head (group C) or a cooling head wrap (group H) were used as cooling devices to decrease the core temperature. The primary outcome was the core temperature. The secondary outcomes were the foot surface temperature and heart rate. We measured all outcomes every 30 min for 240 min after the patient developed hyperthermia. We conducted two-way ANOVA as a pre-planned analysis and also the Bonferroni test as a post hoc analysis.

RESULTS

Twenty patients were randomly assigned to groups C and H. The series of core temperatures in group H were significantly lower than those in group C (p < 0.0001), and post hoc analysis showed that there was no significant difference in core temperatures at T0 between the two groups and statistically significant differences in all core temperatures at T30-240 between the two groups. There was no difference between the two groups' surface temperatures and heart rates.

CONCLUSIONS

Compared to ice packs on the head, head cooling wraps more effectively suppress core temperature elevation during forced-air warming after pediatric cardiac surgery.

The Use of Contrast-Enhanced Ultrasound (CEUS) in the Evaluation of the Neonatal Brain

In recent years, advancements in technology have allowed the use of contrast-enhanced ultrasounds (CEUS) with high-frequency transducers, which in turn, led to new possibilities in diagnosing a variety of diseases and conditions in the field of radiology, including neonatal brain imaging. CEUSs overcome some of the limitations of conventional ultrasounds (US) and Doppler USs. It allows the visualization of dynamic perfusion even in the smallest vessels in the whole brain and allows the quantitative analysis of perfusion parameters. An increasing number of articles are published on the topic of the use of CEUSs on children each year. In the area of brain imaging, the CEUS has already proven to be useful in cases with clinical indications, such as hypoxic-ischemic injuries, stroke, intracranial hemorrhages, vascular anomalies, brain tumors, and infections. We present and discuss the basic principles of the CEUS and its safety considerations, the examination protocol for imaging the neonatal brain, and current and emerging clinical applications.

Maternal and neonatal complications during delivery according to passive versus active second stage in woman with medical conditions (ComPActSS)

Background

The incidence of serious complications during vaginal delivery with a passive second stage in women with medical conditions is unknown.

Methods

Our retrospective cohort study with matched groups (pairing 1 passive with 2 active second stage) included women who had a medical delivery plan from the high risk obstetric team at our center. The primary outcome was a composite of major maternal and neonatal complications.

Results

The primary outcome occurred in 50% (12/24) of women in the passive group versus 35.4% (17/48) (p = 0.24) in the active group. In the passive group, we observed a longer passive second stage of labor (28 vs. 8 min, p < 0.001), a tendency towards more assisted vaginal births (29.2% vs. 12.5%, p = 0.08), and more traumatic deliveries (16.7% vs. 0%, p = 0.012).

Conclusion

The higher proportion of complications in women who had a passive second stage should encourage physicians to make this recommendation only in selected cases.

Low Temperature Delays the Effects of Ischemia in Bergmann Glia and in Cerebellar Tissue Swelling

Cerebral ischemia results in oxygen and glucose deprivation that most commonly occurs after a reduction or interruption in the blood supply to the brain. The consequences of cerebral ischemia are complex and involve the loss of metabolic ATP, excessive K⁺ and glutamate accumulation in the extracellular space, electrolyte imbalance, and brain edema formation. So far, several treatments have been proposed to alleviate ischemic damage, yet few are effective. Here, we focused on the neuroprotective role of lowering the temperature in ischemia mimicked by an episode of oxygen and glucose deprivation (OGD) in mouse cerebellar slices. Our results suggest that lowering the temperature of the extracellular 'milieu' delays both the increases in [K⁺]_e and tissue swelling, two dreaded consequences of cerebellar ischemia. Moreover, radial glial cells (Bergmann glia) display morphological changes and membrane depolarizations that are markedly impeded by lowering the temperature. Overall, in this model of cerebellar ischemia, hypothermia reduces the deleterious homeostatic changes regulated by Bergmann glia.

Characteristics of Children With Cerebral Palsy in the Post-Therapeutic Hypothermia Era

Objectives: To explore the profile of children with cerebral palsy secondary to intrapartum asphyxia treated with therapeutic hypothermia after birth and to compare characteristics of children treated with therapeutic hypothermia with mild vs severe cerebral palsy outcome. Study Design: We identified all children treated with therapeutic hypothermia for intrapartum asphyxia in a single-center tertiary-level neonatal intensive care unit from 2008 to 2018 with a cerebral palsy outcome. We collected perinatal and outcome measures from patient charts. We searched the literature for characteristics of children with cerebral palsy prior to therapeutic hypothermia (historical cohort) to compare to our cohort. We subdivided our cohort into mild vs severe cerebral palsy and compared neonatal characteristics to identify predictors of severe phenotype. Results: Thirty of 355 cooled neonates (8%) developed cerebral palsy. More children had spastic quadriparesis and epilepsy, and fewer had visual impairment in the post-therapeutic hypothermia era compared to the historical cohort, but had similar Gross Motor Function Classification System scores. In our cohort, more children had severe (19 of 30, 63%) compared to mild cerebral palsy (11 of 30, 37%). The severe group had higher mean birth weight, lower 5- and 10-minute Apgar scores, and more often white matter injury with associated deep gray matter injury or near-total injury pattern (P < .05). Conclusions: Our data demonstrated more infants with severe rather than mild cerebral palsy in our cohort treated with therapeutic hypothermia. Birthweight, 5- and 10-minute Apgar scores, and magnetic resonance imaging (MRI) findings were significantly different between mild and severe phenotype groups. Our findings can guide clinicians how to better weigh these factors, when counseling parents in the neonatal period.

Hypoxic-Ischemic Encephalopathy: Changing Outcomes Across the Spectrum

Neonatal hypoxic-ischemic encephalopathy (HIE) is a leading cause of death and neurodevelopmental impairment in neonates. Therapeutic hypothermia (TH) is the only established effective therapy and randomized trials affirm that TH reduces death and disability in moderate-to-severe HIE. Traditionally, infants with mild HIE were excluded from these trials due to the perceived low risk for impairment. Recently, multiple studies suggest that infants with untreated mild HIE may be at significant risk of abnormal neurodevelopmental outcomes. This review will focus on the changing landscape of TH, the spectrum of HIE presentations and their neurodevelopmental outcomes.

Therapeutic Hypothermia Attenuates Cortical Interneuron Loss after Cerebral Ischemia in Near-Term Fetal Sheep

Therapeutic hypothermia significantly improves outcomes after neonatal hypoxic-ischemic (HI) encephalopathy but is only partially protective. There is evidence that cortical inhibitory interneuron circuits are particularly vulnerable to HI and that loss of interneurons may be an important contributor to long-term neurological dysfunction in these infants. In the present study, we examined the hypothesis that the duration of hypothermia has differential effects on interneuron survival after HI. Near-term fetal sheep received sham ischemia or cerebral ischemia for 30 min, followed by cerebral hypothermia from 3 h after ischemia end and continued up to 48 h, 72 h, or 120 h recovery. Sheep were euthanized after 7 days for histology. Hypothermia up to 48 h recovery resulted in moderate neuroprotection of glutamate decarboxylase (GAD)⁺ and parvalbumin⁺ interneurons but did not improve survival of calbindin⁺ cells. Hypothermia up to 72 h recovery was associated with significantly increased survival of all three interneuron phenotypes compared with sham controls. By contrast, while hypothermia up to 120 h recovery did not further improve (or impair) GAD⁺ or parvalbumin⁺ neuronal survival compared with hypothermia up to 72 h, it was associated with decreased survival of calbindin⁺ interneurons. Finally, protection of parvalbumin⁺ and GAD⁺ interneurons, but not calbindin⁺ interneurons, with hypothermia was associated with improved recovery of electroencephalographic (EEG) power and frequency by day 7 after HI. The present study demonstrates differential effects of increasing the duration of hypothermia on interneuron survival after HI in near-term fetal sheep. These findings may contribute to the apparent preclinical and clinical lack of benefit of very prolonged hypothermia.

Identifying Genetic Susceptibility in Neonates With Hypoxic-Ischemic Encephalopathy: A Retrospective Case Series

Neonatal hypoxic-ischemic encephalopathy is a clinical phenomenon that often results from perinatal asphyxia. To mitigate secondary neurologic injury, prompt initial assessment and diagnosis is needed to identify patients eligible for therapeutic hypothermia. However, occasionally neonates present with a clinical picture of hypoxic-ischemic encephalopathy without significant risk factors for perinatal asphyxia. We hypothesized that in patients with genetic abnormalities, the clinical manifestation of those abnormalities may overlap with hypoxic-ischemic encephalopathy criteria, potentially contributing to a causal misattribution. We reviewed 210 charts of infants meeting local protocol criteria for moderate to severe hypoxic-ischemic encephalopathy in neonatal intensive care units in Calgary, Alberta. All patients that met criteria for therapeutic hypothermia were eligible for the study. Data were collected surrounding pregnancy and birth histories, as well as any available genetic or metabolic testing including microarray, gene panels, whole-exome sequencing, and newborn metabolic screens. Twenty-eight patients had genetic testing such as microarray, whole-exome sequencing, or a gene panel, because of clinical suspicion. Ten of 28 patients had genetic mutations, including CDKL5, pyruvate dehydrogenase, CFTR, CYP21A2, ISY1, KIF1A, KCNQ2, SCN9A, MTFMT, and NPHP1. All patients lacked significant risk factors to support a moderate to severe hypoxic-ischemic encephalopathy diagnosis. Treatment was changed in 2 patients because of confirmed genetic etiology. This study demonstrates the importance of identifying genetic comorbidities as potential contributors to a hypoxic-ischemic encephalopathy phenotype in neonates. Early identification of clinical factors that support an alternate diagnosis should be considered when the patient's clinical picture is not typical of hypoxic-ischemic encephalopathy and could aid in both treatment decisions and outcome prognostication.

Variations in care of neonates during therapeutic hypothermia: call for care practice bundle implementation

BACKGROUND

Therapeutic hypothermia (TH) is the gold-standard treatment for moderate and severe neonatal encephalopathy (NE). Care during TH has implications for long-term outcomes. Outcome variability exists among neonatal intensive care units (NICUs) in Canada, but care variations are not understood well. This study examines variations in care practices for neonates with NE treated with TH in NICUs across Canada.

METHODS

A non-anonymous, web-based questionnaire was emailed to tertiary NICUs in Canada providing TH for NE to assess care practices during the first days of life and neurodevelopmental follow-up.

RESULTS

Ninety-two percent (24/26) responded. Centres followed national guidelines regarding the use of the modified Sarnat score to assess the initial severity of NE, the need to initiate TH within the first 6 h of birth, and the importance of follow-up. However, other practices varied, including ventilation mode, definition/treatment of hypotension, routine echocardiography, use of sedation, use of electroencephalogram (EEG), MRI timing, placental analysis, and follow-up duration.

CONCLUSIONS

NICUs across Canada follow available national guidelines, but variations exist in practices for managing NE during TH. Development and implementation of a consensus-based care bundle for neonates during TH may reduce practice variability and improve outcomes.

IMPACT

This survey describes the current HIE care practices and variation among tertiary centres in Canada. Variations exist in the care of neonates with NE treated with TH in NICUs across Canada. This paper Identifies areas of variation that are not discussed in detail in the national guidelines and will help to set up quality improvement initiatives. Elucidating the variation in care practices calls for the creation and implementation of a national, consensus-based care bundle, with the objective to improve the outcomes of these critically ill neonates.

Healthcare organizational factors associated with delayed therapeutic hypothermia in neonatal hypoxic-ischemic encephalopathy: the LyTONEPAL cohort

Initiation of therapeutic hypothermia (TH) within 6 h of life is a major concern for treating neonatal hypoxic ischemic encephalopathy (HIE). We aimed to determine clinical and healthcare organizational factors associated with delayed TH in a French population-based cohort of neonates with moderate/severe HIE. Time to reach a rectal temperature of 34 °C defines optimal and delayed (within and over 6 h, respectively) TH. Clinical and healthcare organizational factors associated with delayed TH were analysed among neonates born in cooling centres (CCs) and non-cooling centres (non-CCs). Among 629 neonates eligible for TH, 574 received treatment (91.3%). TH was delayed in 29.8% neonates and in 20.3% and 36.2% of those born in CCs and non-CCs, respectively. Neonates with moderate HIE were more exposed to delayed TH in both CCs and non-CCs. After adjustment for HIE severity, maternal and neonatal characteristics and circumstances of birth were not associated with increased risk of delayed TH. However, this risk was 2 to 5 times higher in maternities with < 1999 annual births, when the delay between birth and call for transfer (adjusted odds ratio [aOR] 2.47, 95% confidence interval [CI] [1.03 to 5.96]) or between call for transfer and admission (aOR 6.06, 95%CI [2.60 to 14.12]) was > 3 h and when an undesirable event occurred during transfer (aOR 2.66, 95%CI [1.11 to 6.37].  Conclusion: Increasing early identification of neonates who could benefit from TH and access to TH in non-CCs before transfer are modifiable factors that could improve care of neonates with HIE.  Trial registration: The trial was registered at ClinicalTrials.gov (NCT02676063). What is Known: • International recommendations are to initiate therapeutic hypothermia before 6 h of life in neonates with moderate or severe hypoxic ischemic encephalopathy. What is New: •In this French population-based cohort of infants with hypoxic ischemic encephalopathy, nearly one-third of neonates eligible for treatment did not have access to hypothermia in the therapeutic window of 6 h of life. . • Among infants born in non-cooling centres, healthcare organizational factors involved in delayed care were the small size of maternities (1999 annual births), a time interval of more than 3 h between birth and call for transfer and between call for transfer and admission in neonatology, and the occurrence of an undesirable event during transfer.

Therapeutic hypothermia can cause non-infective C-reactive protein elevating

Objective

To analyze the relationship between therapeutic hypothermia (TH) and whole blood high-sensitivity C-reactive protein (hs-CRP) in neonates with hypoxic-ischemic encephalopathy (HIE).

Method

Retrospective analysis was made on the clinical data of hospitalized infants diagnosed with asphyxia in our neonatal intensive care unit from January 2014 to June 2021. According to whether TH was performed, they were divided into two groups, the control group (missed the time in other hospitals and did not receive TH) and the treatment group (TH group). In their first ten days, analysis was made on the hs-CRP, white blood cell (WBC) count, neutrophil percentage, platelet count (PLT), and brain MRI. The correlation analysis was carried out based on the severity of brain injury displayed by the brain MRI and the time of hs-CRP elevation to summarize the relationship between TH and the time of hs-CRP elevation and the severity of HIE.

Results

83 infants were included, 28 in the control group and 55 in the TH group. After birth, 33 infants (60.0%) in the TH group and 2 patients (7.1%) in the control group had elevated hs-CRP, which was statistically significant (P < 0.05). The time window for CRP elevation after TH was 72-96 h after the end of treatment; The results of the brain MRI showed 23 in the TH group and 11in the control group with moderate and severe HIE. 21 infants (all in the TH group) had elevated hs-CRP. MRI showed that the number of infants with mild injury or regular infants whose hs-CRP raised in the TH group was 12, and the rate of hs-CRP elevation was 37.5%; in the control group, the rate was 11.8%. The difference was significant. TH can decrease PLT and WBC, but no significance in the two groups. Blood and sputum cultures were negative in all infants, and there were no signs of infection.

Conclusions

TH can increase the blood hs-CRP of HIE neonates, and the probability of its occurrence is related to the severity of HIE. The heavier the HIE, the higher the risk of hs-CRP elevation after TH; The hs-CRP elevation has little to do with infection, and it doesn't recommend using antibiotics actively.

Clinical practice guidelines for neonatal hypoxic-ischemic encephalopathy: A systematic review using the appraisal of guidelines for research and evaluation (AGREE) II instrument

Background and Objective

To systematically review, critically appraise the quality of recent clinical practice guidelines (CPGs) for neonatal hypoxic ischemic encephalopathy (HIE), and map their recommendations.

Data Sources

CPG databases (GIN, ECRI, NICE, SIGN, DynaMed), Bibliographic databases (PubMed, Embase, CINAHL), and related specialized professional societies (e.g., AAP, CPS, BAPM, RCPCH, and SNS).

Study Selection

Original de-novo developed evidence-based CPGs for HIE, group authorship, Arabic or English languages, and international or national scope. The systematic review was drafted according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement and Johnston et al methodological guide.

Data Extraction

Quality assessment of the included HIE CPGs by the Appraisal of Guidelines for REsearch & Evaluation II (AGREE II) Instrument and report their characteristics, AGREE II ratings, and recommendations.

Data Synthesis

Our search retrieved 2,489 citations, of which two recent HIE CPGs were eligible and appraised: Canadian Paediatric Society (CPS) and Queensland Maternity and Neonatal Services (QMN). The overall assessment of the QMN CPG was superior (83%). Domain 1 (Scope & Purpose) scored (47%, 63%), Domain 2 (Stakeholder Involvement) (72%, 39%), Domain 3 (Rigour of Development) (48%, 43%), Domain 4 (Clarity & Presentation) (100%, 96%), Domain 5 (Applicability) (59%, 9%), and Domain 6 (Editorial Independence) (67%, 17%) for the QMN and CPS CPGs respectively. All appraisers recommended the QMN CPG for use in practice.

Conclusion

The methodological quality of the QMN CPG was superior with the relevant recommendations for its use in neonatal practice.

Limitations

limited to Arabic and English languages.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=258291, identifier: CRD42021258291.

Prospective observational study of the challenges in diagnosing common neonatal conditions in Nigeria and Kenya

OBJECTIVES

Accurate and timely diagnosis of common neonatal conditions is crucial for reducing neonatal deaths. In low/middle-income countries with limited resources, there is sparse information on how neonatal diagnoses are made. The aim of this study was to describe the diagnostic criteria used for common conditions in neonatal units (NNUs) in Nigeria and Kenya.

DESIGN

Prospective observational study. Standard case report forms for suspected sepsis, respiratory disorders, birth asphyxia and abdominal conditions were co-developed by the Neonatal Nutrition Network (https://www.lstmed.ac.uk/nnu) collaborators. Clinicians completed forms for all admissions to their NNUs. Key data were displayed using heatmaps.

SETTING

Five NNUs in Nigeria and two in Kenya comprising the Neonatal Nutrition Network.

PARTICIPANTS

2851 neonates, which included all neonates admitted to the seven NNUs over a 6-month period.

RESULTS

1230 (43.1%) neonates had suspected sepsis, 874 (30.6%) respiratory conditions, 587 (20.6%) birth asphyxia and 71 (2.5%) abdominal conditions. For all conditions and across all NNUs, clinical criteria were used consistently with sparse use of laboratory and radiological criteria.

CONCLUSION

Our findings highlight the reliance on clinical criteria and extremely limited use of diagnostic technologies for common conditions in NNUs in sub-Saharan Africa. This has implications for the management of neonatal conditions which often have overlapping clinical features. Strategies for implementation of diagnostic pathways and investment in affordable and sustainable diagnostics are needed to improve care for these vulnerable infants.

Prolonged Background Suppression Induced by Anticonvulsants Misleading Amplitude-Integrated Encephalography's Interpretation: A Single Case Report

Prognostic role of the amplitude-integrated encephalography (aEEG) is undeniable, but few works focused on the contribution of medications in misleading its interpretation. We report the case of an asphyxiated newborn enrolled for therapeutic hypothermia (TH) that required the simultaneous use of three anticonvulsants, whose administration resulted in a comatose state and in a switch to a flat trace on the aEEG. The prolonged flat trace on the aEEG, pointing toward a state of irreversible brain damage, led to early stop of TH to prevent therapeutic obstinacy; unexpectedly, once Midazolam was weaned off, the aEEG recovered to a discontinuous pattern. The case emphasizes the aEEG's noninfallibility and advises clinicians to consider the potential misleading effects of depressant medications on its interpretation in asphyxiated newborns undergoing TH.

Vitamin D suppresses ferroptosis and protects against neonatal hypoxic-ischemic encephalopathy by activating the Nrf2/HO-1 pathway

BACKGROUND

Hypoxic-ischemic encephalopathy (HIE) is a major cause of neonatal death, and vitamin D (VD) is a neuroprotection nutrition whose deficiency is associated with its risk. However, the mechanism of VD involved in neonatal HIE is not well known.

METHODS

In this experiment a hypoxic-ischemic brain damage (HIBD) model was established by using the Rice-Vannucci method, rats were intraperitoneally injected with 0.1 µg/kg VD every day for two weeks. The brain damage and mitochondria injury were examined by hematoxylin-eosin (HE) staining and transmission electron microscope (TEM), respectively. The oxidation response and inflammatory factors were determined by enzyme-linked immunosorbent assay (ELISA), and the cell viability was determined by Cell Counting Kit-8 (CCK-8). mRNA and protein expression were detected by quantitative real real-time PCR (qRT-PCR), Western blot, and immunofluorescence.

RESULTS

The results showed VD effectively ameliorated brain histologic damage and mitochondria injury induced by hypoxic ischemia (HI). VD elevated the expression of Nrf2 and HO-1, which resulted in increased levels of GPX4, superoxide dismutase (SOD), and glutathione (GSH) and reduced content of malondialdehyde (MDA) and reactive oxygen species (ROS), resulting in decreased ferroptosis in HI-treated rats. Moreover, VD reduced the secretion of inflammatory factors, tumor necrosis factor-α (TNF-α), interleukin (IL)-6, and IL-1β.

CONCLUSIONS

VD suppresses ferroptosis through activation of the Nrf2/HO-1 signaling pathway and exerts a protective role in neonatal HIE.

Causes and Pathophysiology of Acquired Sideroblastic Anemia

The sideroblastic anemias are a heterogeneous group of inherited and acquired disorders characterized by anemia and the presence of ring sideroblasts in the bone marrow. Ring sideroblasts are abnormal erythroblasts with iron-loaded mitochondria that are visualized by Prussian blue staining as a perinuclear ring of green-blue granules. The mechanisms that lead to the ring sideroblast formation are heterogeneous, but in all of them, there is an abnormal deposition of iron in the mitochondria of erythroblasts. Congenital sideroblastic anemias include nonsyndromic and syndromic disorders. Acquired sideroblastic anemias include conditions that range from clonal disorders (myeloid neoplasms as myelodysplastic syndromes and myelodysplastic/myeloproliferative neoplasms with ring sideroblasts) to toxic or metabolic reversible sideroblastic anemia. In the last 30 years, due to the advances in genomic techniques, a deep knowledge of the pathophysiological mechanisms has been accomplished and the bases for possible targeted treatments have been established. The distinction between the different forms of sideroblastic anemia is based on the study of the characteristics of the anemia, age of diagnosis, clinical manifestations, and the performance of laboratory analysis involving genetic testing in many cases. This review focuses on the differential diagnosis of acquired disorders associated with ring sideroblasts.

Short-term outcome of perinatal hypoxic-ischaemic encephalopathy at Chiang Mai University Hospital, Thailand: a 15-year retrospective study

BACKGROUND

The outcome of perinatal hypoxic-ischaemic encephalopathy (HIE) in middle-to-low-income countries varies between regions.

OBJECTIVES

To determine the mortality and morbidity, and factors influencing the deaths of infants with perinatal HIE.

METHODS

A retrospective study was conducted at Chiang Mai University Hospital, Thailand. Perinatal HIE infants of >35 weeks gestation, birthweight ≥2000 g and admitted during 2005-2019 were reviewed. Baseline Characteristics, clinical course and outcome at discharge were compared between the period before and after initiation of therapeutic hypothermia (TH). Risk of death in HIE infants who underwent TH was identified.

RESULTS

A total of 162 HIE infants were included. Compared to the period before TH initiation, the mortality rate was significantly decreased in the TH period. (27% vs. 12.8%, p=0.04) Among 100 HIE infants who underwent TH, the mortality rates was 14%(14/100), of whom 2.5% (2/76) and 50% (12/24) were in the moderate and severe HIE groups. Apgar score at 5 mins ≤1, severe HIE, seizures, hypoglycaemia, organ involvement ≥ five sites, ammonia ≥100 umol/L, lactate ≥14 mmol/L, and requirement for two or more inotropic drugs were risks of death. Multivariate analysis demonstrated that severe HIE (aOR 732.8, 95% CI 4.7-114643, p=0.01) and a need for two or more inotropic drugs (aOR 45.7, 95% CI 1.5-1040, p=0.029) were significant factors for mortality.

CONCLUSION

In the period of TH, perinatal HIE infants had decreased mortality. Severe HIE and a need for two or more inotropic drugs were associated with death in the infant with HIE who underwent TH.Abbreviations: AED: anti-epileptic drug; BW, birthweight; CI: confidence interval; CMU: Chiang Mai University; EEG: electro-encephalogram; GA: gestational age; HIE: hypoxic-ischaemic encephalopathy; IQR: interquartile range; NICU: neonatal intensive care unit; SD: standard deviation; TH: therapeutic hypothermia.

Background suppression of electrical activity is a potential biomarker of subsequent brain injury in a rat model of neonatal hypoxia-ischemia

Electrographic seizures and abnormal background activity in the neonatal electroencephalogram (EEG) may differentiate between harmful versus benign brain insults. Using two animal models of neonatal seizures, electrical activity was recorded in freely behaving rats and examined quantitatively during successive time periods with field-potential recordings obtained shortly after the brain insult (i.e., 0-4 days). Single-channel, differential recordings with miniature wireless telemetry were used to analyze spontaneous electrographic seizures and background suppression of electrical activity after 1) hypoxia-ischemia (HI), which is a model of neonatal encephalopathy that causes acute seizures and a large brain lesion with possible development of epilepsy, 2) hypoxia alone (Ha), which causes severe acute seizures without an obvious lesion or subsequent epilepsy, and 3) sham control rats. Background EEG exhibited increases in power as a function of age in control animals. Although background electrical activity was depressed in all frequency bands immediately after HI, suppression in the β and γ bands was greatest and lasted longest. Spontaneous electrographic seizures were recorded, but only in a few HI-treated animals. Ha-treated rat pups were similar to sham controls, they had no subsequent spontaneous electrographic seizures after the treatment and background suppression was only briefly observed in one frequency band. Thus, the normal age-dependent maturation of electrical activity patterns in control animals was significantly disrupted after HI. Suppression of the background EEG observed here after HI-induced acute seizures and subsequent brain injury may be a noninvasive biomarker for detecting severe brain injuries and may help predict subsequent epilepsy.NEW & NOTEWORTHY Biomarkers of neonatal brain injury are needed. Hypoxia-ischemia (HI) in immature rat pups caused severe brain injury, which was associated with strongly suppressed background EEG. The suppression was most robust in the β and γ bands; it started immediately after the HI injury and persisted for days. Thus, background suppression may be a noninvasive biomarker for detecting severe brain injuries and may help predict subsequent epilepsy.

Variations in practices and outcomes of neonates with hypoxic ischemic encephalopathy treated with therapeutic hypothermia across tertiary NICUs in Canada

OBJECTIVE

To characterize variations in practices and outcomes for neonates with hypoxic-ischemic encephalopathy (HIE) treated with therapeutic hypothermia (TH) across Canadian tertiary Neonatal Intensive Care Units (NICUs).

STUDY DESIGN

Retrospective study of neonates admitted for HIE and treated with TH in 24 tertiary NICUs from the Canadian Neonatal Network, 2010-2020. The two primary outcomes of mortality before discharge and MRI-detected brain injury were compared across NICUs using adjusted standardized ratios (SR) with 95% CI.

RESULTS

Of the 3261 neonates that received TH, 367 (11%) died and 1033 (37%) of the 2822 with MRI results had brain injury. Overall, rates varied significantly across NICUs for mortality (range 5-17%) and brain injury (range 28-51%). Significant variations in use of inotropes, inhaled nitric oxide, blood products, and feeding during TH were identified (p values < 0.01).

CONCLUSION

Significant variations exist in practices and outcomes of HIE neonates treated with hypothermia across Canada.

Expert consensus on grading management of electroencephalogram monitoring in neonates

Neonatal electroencephalogram (EEG) monitoring guidelines have been published by American Clinical Neurophysiology Society, and the expert consensus on neonatal amplitude-integrated EEG (aEEG) has also been published in China. It is difficult to strictly follow the guidelines or consensus for EEG monitoring in different levels of neonatal units due to a lack of EEG monitoring equipment and professional interpreters. The Subspecialty Group of Neonatology, Society of Pediatrics, Chinese Medical Association, established an expert group composed of professionals in neonatology, pediatric neurology, and brain electrophysiology to review published guidelines and consensuses and the articles in related fields and propose grading management recommendations for EEG monitoring in different levels of neonatal units. Based on the characteristics of video EEG and aEEG, local medical resources, and disease features, the expert group recommends that video EEG and aEEG can complement each other and can be used in different levels of neonatal units. The consensus also gives recommendations for promoting collaboration between professionals in neonatology, pediatric neurology, and brain electrophysiology and implementing remote EEG monitoring.

Amplitude-Integrated Electroencephalography: A Primer for Neonatologists and Practitioners in the NICU

Amplitude-integrated electroencephalography (aEEG) is an essential tool used in the NICU to monitor infants with central nervous system pathology and encephalopathy. This review provides a summary of aEEG, including clinical indications, interpretation of different tracing patterns, and seizure identification, which are essential skills for teams caring for sick newborns. We also discuss the limitations of the clinical application of aEEG in this population.

Pharmacometric approach to assist dosage regimen design in neonates undergoing therapeutic hypothermia

BACKGROUND

Therapeutic hypothermia (TH) is the treatment of choice for neonates diagnosed with perinatal asphyxia (PA). Dosing recommendations of various therapeutic agents including antimicrobials were not specifically available for the neonates undergoing TH.

METHODS

A systematic search methodology was used to identify pharmacokinetic (PK) studies of antimicrobials during TH. Antimicrobials with multiple PK studies were identified to create a generalizable PK model. Pharmacometric simulations were performed using the PUMAS software platform to reproduce the results of published studies. A suitable model that could reproduce the results of all other published studies was identified. With the help of a generalizable model, an optimal dosage regimen was designed considering the important covariates of the identified model.

RESULTS

With the systematic search, only gentamicin had multiple PK reports during TH. A generalizable model was identified and the model predictions could match the reported/observed concentrations of publications. Birth weight and serum creatinine were the significant covariates influencing the PK of gentamicin in neonates. A dosage nomogram was designed using pharmacometric simulations to maintain gentamicin concentrations below 10 μg/mL at peak and below 2 μg/mL at trough.

CONCLUSIONS

A generalizable PK model for gentamicin during TH in neonates was identified. Using the model, a dosing nomogram for gentamicin was designed.

IMPACT

Dosing guidelines for antimicrobials during TH in neonates is lacking. This is the first study to identify the generalizable model for gentamicin during TH in neonates. Nomogram, proposed in the study, will aid the clinicians to individualize gentamicin dosing regimen for neonates considering the birth weight and serum creatinine.

Preclinical assessment of thrombin-preconditioned human Wharton's jelly-derived mesenchymal stem cells for neonatal hypoxic-ischaemic brain injury

Hypoxic-ischaemic encephalopathy (HIE) is a type of brain injury affecting approximately 1 million newborn babies per year worldwide, the only treatment for which is therapeutic hypothermia. Thrombin-preconditioned mesenchymal stem cells (MSCs) exert neuroprotective effects by enriching cargo contents and boosting exosome biogenesis, thus showing promise as a new therapeutic strategy for HIE. This study was conducted to evaluate the tissue distribution and potential toxicity of thrombin-preconditioned human Wharton's jelly-derived mesenchymal stem cells (th-hWJMSCs) in animal models before the initiation of clinical trials. We investigated the biodistribution, tumorigenicity and general toxicity of th-hWJMSCs. MSCs were administered the maximum feasible dose (1 × 105 cells/10 µL/head) once, or at lower doses into the cerebral ventricle. To support the clinical use of th-hWJMSCs for treating brain injury, preclinical safety studies were conducted in newborn Sprague-Dawley rats and BALB/c nude mice. In addition, growth parameters were evaluated to assess the impact of th-hWJMSCs on the growth of newborn babies. Our results suggest that th-hWJMSCs are non-toxic and non-tumorigenic in rodent models, survive for up to 7 days in the brain and hold potential for HIE therapy.

Medico-legal considerations in the context of neonatal encephalopathy and therapeutic hypothermia

Neonatal encephalopathy (NE) is a significant complication of the peripartum period. It can lead to lifelong neurologic disabilities, including cerebral palsy, cognitive impairments, developmental delays, and epilepsy. Induced hypothermia is the first therapy, which has shown promise in improving the outcomes for neonates with moderate to severe NE following a presumed intrapartum insult. NE is also a frequent source of medical malpractice litigation. In this paper, we will review salient features of the American Tort System as it pertains to medical malpractice. We will discuss the obstetric medico-legal implications of therapeutic hypothermia and suggest a five-step approach to analyzing neonatal cases for causation, etiology, timing of occurrence, responsibility, and liability. We will close with three illustrative clinical cases.

A Review on the Vagus Nerve and Autonomic Nervous System During Fetal Development: Searching for Critical Windows

The autonomic nervous system (ANS) is one of the main biological systems that regulates the body's physiology. Autonomic nervous system regulatory capacity begins before birth as the sympathetic and parasympathetic activity contributes significantly to the fetus' development. In particular, several studies have shown how vagus nerve is involved in many vital processes during fetal, perinatal, and postnatal life: from the regulation of inflammation through the anti-inflammatory cholinergic pathway, which may affect the functioning of each organ, to the production of hormones involved in bioenergetic metabolism. In addition, the vagus nerve has been recognized as the primary afferent pathway capable of transmitting information to the brain from every organ of the body. Therefore, this hypothesis paper aims to review the development of ANS during fetal and perinatal life, focusing particularly on the vagus nerve, to identify possible "critical windows" that could impact its maturation. These "critical windows" could help clinicians know when to monitor fetuses to effectively assess the developmental status of both ANS and specifically the vagus nerve. In addition, this paper will focus on which factors-i.e., fetal characteristics and behaviors, maternal lifestyle and pathologies, placental health and dysfunction, labor, incubator conditions, and drug exposure-may have an impact on the development of the vagus during the above-mentioned "critical window" and how. This analysis could help clinicians and stakeholders define precise guidelines for improving the management of fetuses and newborns, particularly to reduce the potential adverse environmental impacts on ANS development that may lead to persistent long-term consequences. Since the development of ANS and the vagus influence have been shown to be reflected in cardiac variability, this paper will rely in particular on studies using fetal heart rate variability (fHRV) to monitor the continued growth and health of both animal and human fetuses. In fact, fHRV is a non-invasive marker whose changes have been associated with ANS development, vagal modulation, systemic and neurological inflammatory reactions, and even fetal distress during labor.

Evaluating Neuroprotective Effects of Uridine, Erythropoietin, and Therapeutic Hypothermia in a Ferret Model of Inflammation-Sensitized Hypoxic-Ischemic Encephalopathy

Perinatal hypoxic-ischemic (HI) brain injury, often in conjunction with an inflammatory insult, is the most common cause of death or disability in neonates. Therapeutic hypothermia (TH) is the standard of care for HI encephalopathy in term and near-term infants. However, TH may not always be available or efficacious, creating a need for novel or adjunctive neurotherapeutics. Using a near-term model of inflammation-sensitized HI brain injury in postnatal day (P) 17 ferrets, animals were randomized to either the control group (n = 43) or the HI-exposed groups: saline vehicle (Veh; n = 42), Ur (uridine monophosphate, n = 23), Epo (erythropoietin, n = 26), or TH (n = 24) to test their respective therapeutic effects. Motor development was assessed from P21 to P42 followed by analysis of cortical anatomy, ex vivo MRI, and neuropathology. HI animals took longer to complete the motor assessments compared to controls, which was exacerbated in the Ur group. Injury resulted in thinned white matter tracts and narrowed cortical sulci and gyri, which was mitigated in Epo-treated animals in addition to normalization of cortical neuropathology scores to control levels. TH and Epo treatment also resulted in region-specific improvements in diffusion parameters on ex vivo MRI; however, TH was not robustly neuroprotective in any behavioral or neuropathological outcome measures. Overall, Ur and TH did not provide meaningful neuroprotection after inflammation-sensitized HI brain injury in the ferret, and Ur appeared to worsen outcomes. By comparison, Epo appears to provide significant, though not complete, neuroprotection in this model.

Hemodynamic response to milrinone for refractory hypoxemia during therapeutic hypothermia for neonatal hypoxic ischemic encephalopathy

OBJECTIVE

Characterize the impact of milrinone on arterial pressure of neonates with persistent hypoxemic respiratory failure (HRF) and hypoxic ischemic encephalopathy (HIE) treated with inhaled nitric oxide and therapeutic hypothermia (TH).

STUDY DESIGN

Retrospective cohort study. Arterial pressure was assessed hourly for 24 h. The primary outcome was change in diastolic arterial pressure (DAP).

RESULTS

56 patients were included [(i) cases: HIE/TH who received milrinone (n = 9), (ii) Milrinone controls (n = 17), (iii) HIE controls (n = 30)]. Baseline demographics, severity of HRF and arterial pressure were comparable between groups. Only milrinone treated patients with HIE/TH had a marked drop in DAP in the first hour, which persisted for more than 12 h despite escalation in inotropes (p = 0.008).

CONCLUSION

Milrinone treated patients with HRF and HIE/TH develop profound reduction in DAP and require escalation of cardiovascular support. The risk benefit profile of milrinone should be considered and pharmacological studies are warranted to evaluate drug metabolism and clearance in this population.