Effect of therapeutic hypothermia on renal and myocardial function in asphyxiated (near) term neonates: A systematic review and meta-analysis

Echinocystic acid ameliorates ischemic acute kidney injury in neonatal rats by attenuating ferroptosis via the Nrf2/GPX4 pathway

Acute kidney injury (AKI) is the most common complication in neonates with hypoxic-ischemic encephalopathy (HIE), significantly contributing to both morbidity and mortality, and targeting key pathological processes, such as inflammation, ferroptosis and apoptosis, could be an effective approach to improving survival outcomes in these patients. In this context, echinocystic acid (EA), a pentacyclic triterpene, has shown promising anti-inflammatory, antioxidant, and anti-apoptotic effects in various disease models, suggesting its potential as a therapeutic agent for AKI in HIE. To evaluate the therapeutic potential and underlying mechanisms of EA in ameliorating ischemia/reperfusion (IR)-induced AKI in neonatal rats. Seven-day-old neonatal rat pups were subjected to an IR injury model to induce AKI and treated with EA via intraperitoneal injection. The effects of EA on renal injury were assessed using western blotting, terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL), immunofluorescence, reverse transcription-quantitative polymerase chain reaction (RT-qPCR), enzyme-linked immunosorbent assay (ELISA), and hematoxylin and eosin (H&E) staining. Treatment with EA significantly reduced IR-induced renal pathology and injury scores, as well as serum levels of blood urea nitrogen (BUN) and creatinine (Cr). In addition, EA diminished the release of pro-inflammatory cytokines and reduced the levels of F4/80, a macrophage marker, in the IR-treated pups. EA also attenuated ferroptosis, as evidenced by decreased levels of iron (Fe2⁺), reactive oxygen species (ROS), myeloperoxidase (MPO), and malondialdehyde (MDA), while simultaneously increasing the activity of antioxidant enzymes such as catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD), and glutathione (GSH). Furthermore, EA reduced apoptosis, as demonstrated by lower levels of cleaved caspase 3 and cleaved poly(ADP-ribose) polymerase (PARP). Mechanistically, EA activated the Nrf2/GPX4 pathway, and inhibition of Nrf2 with ML385 reversed EA's beneficial effects on ferroptosis, inflammation, and renal injury. EA may relieve ischemic AKI in neonatal rats by modulating inflammation, ferroptosis and apoptosis, through the activation of the Nrf2/GPX4 pathway, indicating that it could be a promising therapeutic agent for AKI in neonates.

Population Pharmacokinetics of Caffeine in Infants with Hypoxic-Ischemic Encephalopathy: A Phase I, Dose-Escalating Trial

The mainstay of treatment for infants with hypoxic-ischemic encephalopathy (HIE) is cooling. Caffeine may be an important adjunct to cooling and provide neuroprotection via its anti-inflammatory and anti-oxidative properties. This study aimed to characterize caffeine pharmacokinetics in term infants with HIE receiving cooling. In this phase 1, dose-escalating study, enrolled infants received IV caffeine 20 mg/kg followed by up to two daily doses of 5 or 10 mg/kg. A population pharmacokinetic analysis was performed using NONMEM (v7.5). The effects of clinical covariates, including cooling, on pharmacokinetic parameters were evaluated. Dosing simulations were performed to evaluate the percentage of plasma exposures in the reference range (15-25 mg/L). Seventeen infants were included in model development. A one-compartment model best fit the data. Population clearance was 0.445 L/h/70 kg and volume of distribution was 87.1 L/70 kg. Current dosing regimens (20 mg/kg followed by 5 mg/kg) resulted in 89.5% of infants having at least one simulated exposure below the reference range across the dosing interval. Dosing regimens of 30 mg/kg followed by 5 or 10 mg/kg were predicted to result in more than half of infants achieving simulated exposures in the reference range, with ≤20% of infants having simulated exposures in the toxic range (>46 mg/L). Term infants with HIE had similar weight-normalized clearance but higher weight-normalized volume of distribution compared to prior studies in preterm infants without HIE or cooling. While exposure targets for neuroprotection in HIE are unknown, this phase 1 study suggests alternate dosing strategies should be considered in future studies.

Role of the very low frequencies of the renal oxygen saturation signal in acute kidney injury in newborns with perinatal asphyxia

Objective

Renal autoregulation, hemodynamic response, and endothelial dysfunction play significant roles in acute kidney injury (AKI) during perinatal asphyxia. A third mechanism of autoregulation, involving very low-frequency oscillations, has been described. This study aimed to evaluate the relationship between the power of the very low-frequency component of the Fast Fourier Transform (FFT) and AKI during therapeutic hypothermia (TH) treatment in neonates with perinatal asphyxia.

Study design

A retrospective longitudinal study was conducted on neonates with moderate and severe perinatal asphyxia. AKI was defined as a decrease of less than 33% in the serum creatinine level by day 3. The power of the very low-frequency component in the FFT was assessed by analyzing renal oxygen saturation using near-infrared spectroscopy (NIRS), focusing on a frequency band of approximately 0.01 Hz. Bivariate analyses were performed to explore the association between the power of the very-low-frequency component and AKI. The predictive ability of this component for AKI was evaluated using a receiver operating characteristic (ROC) curve. Additionally, a generalized estimating equation (GEE) was developed to investigate whether changes in the power of the very-low-frequency component during treatment differed according to the presence of AKI.

Results

A total of 91 patients were included in the study, of whom 15 (16.5%) developed AKI. Neonates with AKI exhibited a significantly lower power of the very low-frequency component on the second day of treatment (p = 0.001). This component demonstrated good predictive ability for AKI (ROC curve 0.77, 95% CI 0.63-0.90).

Conclusion

Among neonates with perinatal asphyxia who developed AKI, a lower power of the very-low-frequency component in FFT (approximately 0.01 Hz) was observed on the second day of therapeutic hypothermia. This finding suggests that alterations in very-low-frequency oscillations may reflect endothelial dysfunction and contribute to the development of AKI, warranting further investigation in larger cohorts.

Case Report: Hypercalcemia, subcutaneous fat necrosis and nephrocalcinosis in neonates who undergo therapeutic hypothermia: a not so rare association, with different onset time

Subcutaneous fat necrosis (SCFN) in newborns is an uncommon and self-limiting non-infectious panniculitis. It can occur in the first weeks of life in full-term newborns with hypoxic-ischemic encephalopathy who underwent therapeutic hypothermia. Hypercalcemia may develop and has been implicated as the cause of several complications as nephrocalcinosis. Hypercalcemia has been previously reported to appear only after resolution of skin lesions. Herein, we report how hypercalcemia can be evident already at diagnosis of subcutaneous fat necrosis after therapeutic hypothermia and can be associated with an early onset developing nephrocalcinosis. We compare two cases of these uncommon findings and review the recent literature.

Population pharmacokinetics of vancomycin in term neonates with perinatal asphyxia treated with therapeutic hypothermia

AIMS

Little is known about the population pharmacokinetics (PPK) of vancomycin in neonates with perinatal asphyxia treated with therapeutic hypothermia (TH). We aimed to describe the PPK of vancomycin and propose an initial dosing regimen for the first 48 h of treatment with pharmacokinetic/pharmacodynamic target attainment.

METHODS

Neonates with perinatal asphyxia treated with TH were included from birth until Day 6 in a multicentre prospective cohort study. A vancomycin PPK model was constructed using nonlinear mixed-effects modelling. The model was used to evaluate published dosing guidelines with regard to pharmacokinetic/pharmacodynamic target attainment. The area under the curve/minimal inhibitory concentration ratio of 400-600 mg*h/L was used as target range.

RESULTS

Sixteen patients received vancomycin (median gestational age: 41 [range: 38-42] weeks, postnatal age: 4.4 [2.5-5.5] days, birth weight: 3.5 [2.3-4.7] kg), and 112 vancomycin plasma concentrations were available. Most samples (79%) were collected during the rewarming and normothermic phase, as vancomycin was rarely initiated during the hypothermic phase due to its nonempirical use. An allometrically scaled 1-compartment model showed the best fit. Vancomycin clearance was 0.17 L/h, lower than literature values for term neonates of 3.5 kg without perinatal asphyxia (range: 0.20-0.32 L/h). Volume of distribution was similar. Published dosing regimens led to overexposure within 24 h of treatment. A loading dose of 10 mg/kg followed by 24 mg/kg/day in 4 doses resulted in target attainment.

CONCLUSION

Results of this study suggest that vancomycin clearance is reduced in term neonates with perinatal asphyxia treated with TH. Lower dosing regimens should be considered followed by model-informed precision dosing.

Renal artery flow alterations in neonates with hypoxic ischemic encephalopathy

BACKGROUND

To compare kidney blood flow and kidney function tests in infants with hypoxic ischemic encephalopathy (HIE), and the effects of therapeutic hypothermia (TH) during the first 7 days of life.

METHODS

Fifty-nine infants with HIE were prospectively evaluated. Infants with moderate-severe HIE who required TH were classified as group 1 (n = 36), infants with mild HIE were classified as group 2 (n = 23), and healthy infants were classified as group 3 (n = 60). Kidney function tests were evaluated on the sixth hour, third and seventh days of life in Group 1 and Group 2, and on the sixth hour and third day of life in group 3. Renal artery (RA) Doppler ultrasonography (dUS) was performed in all infants on the first, third, and seventh days of life.

RESULTS

Systolic and end diastolic blood flow in RA tended to increase and RA resistive index (RI) tended to decrease with time in group 1 (p = 0.0001). While end diastolic blood flow rates in RA on the third day were similar in patients with severe HIE and mild HIE, it was lower in patients with mild-moderate-severe HIE than healthy newborns. On the seventh day, all three groups had similar values (p > 0.05). Serum blood urea nitrogen (BUN), creatinine, uric acid, and cystatin C levels gradually decreased and glomerular filtration rate (GFR) gradually increased during TH in group 1 (p = 0.0001). Serum creatinine levels gradually decreased while GFR gradually increased during the study period in group 2.

CONCLUSIONS

Therapeutic hypothermia seems to help restore renal blood flow and kidney functions during the neonatal adaptive period with its neuroprotective properties.

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).

A Population Model of Time-Dependent Changes in Serum Creatinine in (Near)term Neonates with Hypoxic-Ischemic Encephalopathy During and After Therapeutic Hypothermia

The objective was to apply a population model to describe the time course and variability of serum creatinine (sCr) in (near)term neonates with moderate to severe encephalopathy during and after therapeutic hypothermia (TH). The data consisted of sCr observations up to 10 days of postnatal age in neonates who underwent TH during the first 3 days after birth. Available covariates were birth weight (BWT), gestational age (GA), survival, and acute kidney injury (AKI). A previously published population model of sCr kinetics in neonates served as the base model. This model predicted not only sCr but also the glomerular filtration rate normalized by its value at birth (GFR/GFR0). The model was used to compare the TH neonates with a reference full term non-asphyxiated population of neonates. The estimates of the model parameters had good precision and showed high between subject variability. AKI influenced most of the estimated parameters denoting a strong impact on sCr kinetics and GFR. BWT and GA were not significant covariates. TH transiently increased [Formula: see text] in TH neonates over the first days compared to the reference group. Asphyxia impacted not only GFR, but also the [Formula: see text] synthesis rate. We also observed that AKI neonates exhibit a delayed onset of postnatal GFR increase and have a higher [Formula: see text] synthesis rate compared to no-AKI patients. Our findings show that the use of [Formula: see text] as marker of renal function in asphyxiated neonates treated with TH to guide dose selection for renally cleared drugs is challenging, while we captured the postnatal sCr patterns in this specific population.

Prognostic value of neutrophil-lymphocyte ratio in out-of-hospital cardiac arrest patients receiving targeted temperature management: An observational cohort study

BACKGROUND

Out-hospital cardiac arrest (OHCA) is a major cause of mortality and morbidity worldwide. The magnitude of the post-resuscitation inflammatory response is closely related to the severity of the circulatory dysfunction. Currently, targeted temperature management (TTM) has become an essential part of the post-resuscitation care for unconscious OHCA survivors. Some novel prognostic inflammatory markers may help predict outcomes of OHCA patients after TTM.

METHODS

A retrospective observational cohort study of 65 OHCA patients treated with TTM was conducted in a tertiary hospital in Taiwan. The primary outcome measure was in-hospital mortality. Baseline and post-TTM neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte (PLR), and the systemic immune inflammation index (SII) were identified as potential predictors.

RESULTS

These patients had a mean age of 62.2 ± 17.0 years. Among the total sample, 53.8% had an initial shockable rhythm and 61.5% had a presumed cardiac etiology. The median resuscitation duration was 20 min (IQR 13.5-28.5) and 60% received subsequent percutaneous coronary intervention. The mean baseline NLR, PLR and SII were 7.5 ± 16.7, 118 ± 207, 1395 ± 3004, and the mean post-TTM NLR, PLR and SII were 15.0 ± 11.6, 206 ± 124, 2369 ± 2569, respectively. Using multiple logistic regression analysis, post-TTM NLR was one of the independent factors which predicted in-hospital mortality (adjusted odds ratio (aOR): 1.249, 95% confidence interval (CI): 1.040-1.501, p = 0.017).

CONCLUSION

Post-TTM NLR is a predictor of in-hospital mortality in OHCA patients who underwent TTM.

Pharmacokinetics during therapeutic hypothermia in neonates: from pathophysiology to translational knowledge and physiologically-based pharmacokinetic (PBPK) modeling

INTRODUCTION

Perinatal asphyxia (PA) still causes significant morbidity and mortality. Therapeutic hypothermia (TH) is the only effective therapy for neonates with moderate to severe hypoxic-ischemic encephalopathy after PA. These neonates need additional pharmacotherapy, and both PA and TH may impact physiology and, consequently, pharmacokinetics (PK) and pharmacodynamics (PD).

AREAS COVERED

This review provides an overview of the available knowledge in PubMed (until November 2022) on the pathophysiology of neonates with PA/TH. In vivo pig models for this setting enable distinguishing the effect of PA versus TH on PK and translating this effect to human neonates. Available asphyxia pig models and methodological considerations are described. A summary of human neonatal PK of supportive pharmacotherapy to improve neurodevelopmental outcomes is provided.

EXPERT OPINION

To support drug development for this population, knowledge from clinical observations (PK data, real-world data on physiology), preclinical (in vitro and in vivo (minipig)) data, and molecular and cellular biology insights can be integrated into a predictive physiologically-based PK (PBPK) framework, as illustrated by the I-PREDICT project (Innovative physiology-based pharmacokinetic model to predict drug exposure in neonates undergoing cooling therapy). Current knowledge, challenges, and expert opinion on the future directions of this research topic are provided.

Population Pharmacokinetics and Dosing Optimization of Ceftazidime in Term Asphyxiated Neonates during Controlled Therapeutic Hypothermia

Ceftazidime is an antibiotic commonly used to treat bacterial infections in term neonates undergoing controlled therapeutic hypothermia (TH) for hypoxic-ischemic encephalopathy after perinatal asphyxia. We aimed to describe the population pharmacokinetics (PK) of ceftazidime in asphyxiated neonates during hypothermia, rewarming, and normothermia and propose a population-based rational dosing regimen with optimal PK/pharmacodynamic (PD) target attainment. Data were collected in the PharmaCool prospective observational multicenter study. A population PK model was constructed, and the probability of target attainment (PTA) was assessed during all phases of controlled TH using targets of 100% of the time that the concentration in the blood exceeds the MIC (T>MIC) (for efficacy purposes and 100% T>4×MIC and 100% T>5×MIC to prevent resistance). A total of 35 patients with 338 ceftazidime concentrations were included. An allometrically scaled one-compartment model with postnatal age and body temperature as covariates on clearance was constructed. For a typical patient receiving the current dose of 100 mg/kg of body weight/day in 2 doses and assuming a worst-case MIC of 8 mg/L for Pseudomonas aeruginosa, the PTA was 99.7% for 100% T>MIC during hypothermia (33.7°C; postnatal age [PNA] of 2 days). The PTA decreased to 87.7% for 100% T>MIC during normothermia (36.7°C; PNA of 5 days). Therefore, a dosing regimen of 100 mg/kg/day in 2 doses during hypothermia and rewarming and 150 mg/kg/day in 3 doses during the following normothermic phase is advised. Higher-dosing regimens (150 mg/kg/day in 3 doses during hypothermia and 200 mg/kg/day in 4 doses during normothermia) could be considered when achievements of 100% T>4×MIC and 100% T>5×MIC are desired.

Predictive value of cord blood myocardial enzyme and troponin levels for myocardial injury after neonatal asphyxia

PURPOSES

To assess the value of myocardial enzymes and troponins in cord blood in the early diagnosis of myocardial injury after neonatal asphyxia.

METHODS

We retrospectively analyzed the clinical data of 50 cases of perinatal asphyxia neonates and 40 normal newborns in this study. The clinical manifestation, electrocardiograph (ECG) and echocardiography result, and the cord blood myocardial enzyme and troponin levels were compared between the two groups. The receiver operating characteristic (ROC) curve analysis was used to explore the diagnostic value of cord blood myocardial enzymes and troponins for myocardial injury after neonatal asphyxia.

RESULTS

All cases in the asphyxia group had different degrees of clinical manifestations of myocardial injury, as well as ECG and echocardiography abnormalities. Compared with the control group, cord blood aspartate aminotransferase (AST), lactate dehydrogenase (LDH), creatine kinase (CK), creatine kinase isoenzyme MB (CK-MB), cardiac troponin T (cTNT), and cardiac troponin I (cTNI) levels in the asphyxia group were all elevated (all P < 0.05). Levels of the six biomarkers were all significantly higher in asphyxiated newborns with myocardial injury than in asphyxiated newborns without myocardial injury (all P < 0.05). ROC curve analyses showed that cord blood levels of CK-MB, cTNT, and cTNI could be used to differentiate asphyxiated newborn with and without myocardial damage. Calculation of AUC (area under curve) values indicated that CK-MB, cTNT, and cTNI had significant discriminatory ability (P=0.014, 0.021, and 0.009, respectively). The optimal cutoff value of CK-MB, cTNT, and cTNI were 135.4 U/L, 112.6 ng/L, and 55.3 ng/L, respectively.

CONCLUSIONS

Cord blood CK-MB, cTNT, and cTNI levels could be used for early prediction of myocardial injury after neonatal asphyxia.

Neonatal hypoxic ischemic encephalopathy increases acute kidney injury urinary biomarkers in a rat model

Hypoxic ischemic encephalopathy (HIE) is associated with acute kidney injury (AKI) in neonates with birth asphyxia. This study aimed to utilize urinary biomarkers to characterize AKI in an established neonatal rat model of HIE. Day 7 Sprague-Dawley rat pups underwent HIE using the Rice-Vannucci model (unilateral carotid ligation followed by 120 mins of 8% oxygen). Controls included no surgery and sham surgery. Weights and urine for biomarkers (NGAL, osteopontin, KIM-1, albumin) were collected the day prior, daily for 3 days post-intervention, and at sacrifice day 14. Kidneys and brains were processed for histology. HIE pups displayed histological evidence of kidney injury including damage to the proximal tubules, consistent with resolving acute tubular necrosis, and had significantly elevated urinary levels of NGAL and albumin compared to sham or controls 1-day post-insult that elevated for 3 days. KIM-1 significantly increased for 2 days post-HIE. HIE did not significantly alter osteopontin levels. Seven days post-start of experiment, controls were 81.2% above starting weight compared to 52.1% in HIE pups. NGAL and albumin levels inversely correlated with body weight following HIE injury. The AKI produced by the Rice-Vannucci HIE model is detectable by urinary biomarkers, which can be used for future studies of treatments to reduce kidney injury.

Incidence and outcomes of intrapartum-related neonatal encephalopathy in low-income and middle-income countries: a systematic review and meta-analysis

AIM

To examine the incidence of intrapartum-related neonatal encephalopathy, and neonatal mortality and neurodevelopmental outcomes associated with it in low-income and middle-income countries.

METHODS

Reports were included when neonatal encephalopathy diagnosed clinically within 24 hours of birth in term or near-term infants born after intrapartum hypoxia-ischaemia defined as any of the following: (1) pH≤7.1 or base excess ≤-12 or lactate ≥6, (2) Apgar score ≤5 at 5 or 10 min, (3) continuing resuscitation at 5 or 10 min or (4) no cry from baby at 5 or 10 min. Peer-reviewed articles were searched from Ovid MEDLINE, Cochrane, Web of Science and WHO Global Index Medicus with date limits 1 November 2009 to 17 November 2021. Risk of bias was assessed using modified Newcastle Ottawa Scale. Inverse variance of heterogenicity was used for meta-analyses.

RESULTS

There were 53 reports from 51 studies presenting data on 4181 children with intrapartum-related neonatal encephalopathy included in the review. Only five studies had data on incidence, which ranged from 1.5 to 20.3 per 1000 live births. Neonatal mortality was examined in 45 studies and in total 636 of the 3307 (19.2%) infants died. Combined outcome of death or moderate to severe neurodevelopmental disability was reported in 19 studies and occurred in 712 out of 1595 children (44.6%) with follow-up 1 to 3.5 years.

CONCLUSION

Though there has been progress in some regions, incidence, case mortality and morbidity in intrapartum-related neonatal encephalopathy has been static in the last 10 years.

PROSPERO REGISTRATION NUMBER

CRD42020177928.

Interventions for preventing and treating acute kidney injury in children

This is a protocol for a Cochrane Review (intervention). The objectives are as follows:

This review aims to look at the benefits and harms of all pharmacological interventions except dialysis for the prevention and treatment of AKI.

Short-term outcome and complications of therapeutic hypothermia in neonates with moderate-to-severe hypoxic ischaemic encephalopathy: a single-centre retrospective observational study in a hospital in Mumbai, India

BACKGROUND

Although shown to reduce death or disability in moderate-to-severe hypoxic ischaemic encephalopathy (HIE), therapeutic hypothermia (TH) has recently been associated with an increase in adverse events in low- and middle-income countries (LMIC).

AIM

To determine the clinical characteristics, complications and short-term outcome in neonates receiving TH in King Edward Memorial Hospital, Mumbai, India.

METHODS

A retrospective single-centre study of neonates with moderate-to-severe HIE who received TH from 1 January 2018 to 31 December 2021 was undertaken. TH was provided as per the unit's protocol using either a servo-controlled device or a phase-changing material (PCM).

RESULTS

One hundred and fifty-five neonates were included with 94.2% intramural births. Mean gestation and birthweight were 38.6 (1.5) weeks and 2776.7 (431) g, respectively. HIE staging was moderate in 87.1% and severe in 12.9%, with a mean cord pH of 6.93 (0.14) and seizures in 38.7%. Adverse events included shock (50.3%), clinically significant bleeding (16%), acute kidney injury (6.7%), culture-positive sepsis (11.6%), persistent pulmonary hypertension (9%), bradycardia (9%), food intolerance (14.9%) and premature termination (7.1%). A servo-controlled device (15.5%) or PCM (84.5%) was used, with comparable adverse events. 84.5% of the neonates were discharged, 7.1% discharged against medical advice and 8.4% died. Detailed neurological assessment at discharge/discharge against medical advice suggested neurological impairment in 128 (87.1%) neonates.

CONCLUSION

Adverse events during TH range from asymptomatic laboratory abnormalities to life-threatening complications, which are manageable in well equipped units. Neurological impairment at discharge in neonates who received cooling mandates strict neurological follow-up.Abbreviations: aEEG: amplitude-integrated EEG; AKI: acute kidney injury; BW: birthweight; EEG: electro-encephalogram; GA: gestational age; HELIX: hypothermia for encephalopathy in low- and middle-income countries; HIE: hypoxic ischaemic encephalopathy; IVH: intraventricular haemorrhage; LMIC: low- and middle-income countries; NICHD: National Institute of Child Health and Human Development; NICU: neonatal intensive care unit; PPHN: persistent pulmonary hypertension of newborn; PCM: phase-changing material; SGA: small-for-gestational age; TH: therapeutic hypothermia.

Acute kidney injury in infants with hypothermia-treated hypoxic-ischaemic encephalopathy: An observational population-based study

AIM

To describe incidence and outcome of acute kidney injury (AKI) in infants with hypothermia-treated hypoxic-ischaemic encephalopathy (HIE).

METHODS

This observational population-based study included all term and near-term infants with hypothermia-treated HIE born between 2007 and 2009 in greater Stockholm. The KDIGO definition modified for neonatal patients was used to identify infants with AKI. We analysed association between AKI and neonatal morbidity/mortality. Furthermore, we calculated estimated glomerular filtration rate (eGFR) at the age of 10-12 years.

RESULTS

Out of 83,939 live births in the Stockholm region, 66 infants underwent hypothermia treatment due to HIE. Out of 65 included infants, 45% suffered AKI. Degree of AKI correlated with HIE severity. One infant needed kidney replacement therapy; others were treated conservatively. AKI was associated with increased mortality and need for blood products (p < 0.05). eGFR at age 10-12 years was available for 72% of survivors. Nine children (21%) had subnormal eGFR, with no difference between those with and without a history of neonatal AKI.

CONCLUSION

Despite therapeutic hypothermia, AKI remains a common complication in infants with HIE and is associated with increased neonatal mortality. Twenty-one per cent of children had subnormal eGFR at 10-12 years, highlighting the need for long-term follow-up of renal function.

Hypothermia cannot ameliorate renal fibrosis after asphyxia in the newborn piglet

BACKGROUND

The effects of therapeutic hypothermia (TH) on renal function are not widely reported, especially in longer term animal models. The hypothesis of this study was that TH of the kidneys of hypoxic-ischemic newborn piglets would reduce pathological renal fibrosis.

METHODS

Twenty-five newborn piglets obtained within 24 h of birth were classified into a control group (n = 5), an hypoxic insult with normothermia (HI-NT) group (n = 12), and an hypoxic insult with TH (HI-TH) group (33.5 °C ± 0.5 °C for 24 h; n = 8). Five days after the insult, all piglets were sacrificed under deep anesthesia by isoflurane inhalation. The kidneys were perfused with phosphate-buffered paraformaldehyde and immersed in formalin buffer. Territory fibrosis was studied and scored in the renal medulla using Azan staining.

RESULTS

Fibrosis area scores (means ± standard deviations) based on Azan staining were 1.00 ± 0.46 in the control group, 2.85 ± 0.93 in the HI-NT group, and 3.58 ± 1.14 in the HI-TH group. The fibrosis area of the HI-NT and HI-TH groups was larger than that of the control. The HI-NT and HI-TH groups were not statistically different.

CONCLUSIONS

Renal fibrosis is affected by perinatal asphyxia and cannot be prevented by TH, based on histopathological findings.

Serum Creatinine Patterns in Neonates Treated with Therapeutic Hypothermia for Neonatal Encephalopathy

INTRODUCTION

There is large variability in kidney function and injury in neonates with neonatal encephalopathy (NE) treated with therapeutic hypothermia (TH). Acute kidney injury (AKI) definitions that apply categorical approaches may lose valuable information about kidney function in individual patients. Centile serum creatinine (SCr) over postnatal age (PNA) may provide more valuable information in TH neonates.

METHODS

Data from seven TH neonates and one non-TH-treated, non-NE control cohorts were pooled in a retrospective study. SCr centiles over PNA, and AKI incidence (definition: SCr ↑≥0.3 mg/dL within 48 h, or ↑ ≥1.5 fold vs. the lowest prior SCr within 7 days) and mortality were calculated. Repeated measurement linear models were applied to SCr trends, modeling SCr on PNA, birth weight or gestational age (GA), using heterogeneous autoregressive residual covariance structure and maximum likelihood methods. Findings were compared to patterns in the control cohort.

RESULTS

Among 1,136 TH neonates, representing 4,724 SCr observations, SCr (10th-25th-50th-75th-90th-95th) PNA centiles (day 1-10) were generated. In TH neonates, the AKI incidence was 132/1,136 (11.6%), mortality 193/1,136 (17%). AKI neonates had a higher mortality (37.2-14.3%, p < 0.001). Median SCr patterns over PNA were significantly higher in nonsurvivors (p < 0.01) or AKI neonates (p < 0.001). In TH-treated neonates, PNA and GA or birth weight explained SCr variability. Patterns over PNA were significantly higher in TH neonates to controls (801 neonates, 2,779 SCr).

CONCLUSIONS

SCr patterns in TH-treated NE neonates are specific. Knowing PNA-related patterns enable clinicians to better assess kidney function and tailor pharmacotherapy, fluids, or kidney supportive therapies.

A single dose of aminophylline administration during therapeutic hypothermia; does it make a difference in glomerular filtration rate?

Aminophylline has been demonstrated to be effective in improving renal functions of the infants suffering from acute kidney injury (AKI) due to perinatal asphyxia. We aimed to evaluate the effect of a single-dose aminophylline on estimated glomerular filtration rate (eGFR), urine output (UO), and incidence and severity of AKI according to the pediatric-modified RIFLE and neonatal RIFLE criteria in newborns with perinatal asphyxia under therapeutic hypothermia. This was a single-center, retrospective cohort study including newborns (gestational age ≥36 weeks) who underwent therapeutic hypothermia due to hypoxic ischemic encephalopathy between 2016 and 2019. Demographic and clinical data were obtained from electronic medical records and patient files. Two patient groups were established: aminophylline group and control group which were only under therapeutic hypothermia. Twenty-one newborns were in the aminophylline group and 13 newborns were in the control group. Our study revealed that on the third day of life (DOL), eGFR was significantly higher in the control group (p=0.025), but UO was significantly higher in the aminophylline group (p=0.021). In the aminophylline group, eGFR on the first DOL was higher than the value on the second DOL (p=0.017) while UO was higher on the second and third DOL compared to the first DOL (1-2 DOL p=0.006, and 1-3 DOL p=0.004). However, in the control group, there was no statistically significant difference in UO over the four DOL. Both groups were similar in the presence, severity, and outcome of AKI.Conclusion: This study demonstrated that aminophylline increases UO even in the infants under therapeutic hypothermia. However, the eGFR did not significantly increase in the aminophylline group. Understanding how therapeutic hypothermia affects pharmacokinetics may help us improve our results in future studies. What is known: • Therapeutic hypothermia (TH) reduces the incidence of acute kidney injury in asphyxiated newborns. • Aminophylline is effective in improving renal functions in asphyxiated newborns. What is new: • This is the first study evaluating the effect of a single dose of aminophylline on renal functions in newborns under TH. • A single dose of aminophylline administration in newborns under TH was associated with increased urine output especially on the third day of life. However, no significant increase was detected in glomerular filtration rate associated with aminophylline administration.

Creatinine Trends and Patterns in Neonates Undergoing Whole Body Hypothermia: A Systematic Review

Many neonates undergoing whole body hypothermia (WBH) following moderate to severe perinatal asphyxia may also suffer from renal impairment. While recent data suggest WBH-related reno-protection, differences in serum creatinine (Scr) patterns to reference patterns were not yet reported. We therefore aimed to document Scr trends and patterns in asphyxiated neonates undergoing WBH and compared these to centiles from a reference Scr data set of non-asphyxiated (near)term neonates. Using a systematic review strategy, reports on Scr trends (mean ± SD, median or interquartile range) were collected (day 1-7) in WBH cohorts and compared to centiles of an earlier reported reference cohort of non-asphyxia cases. Based on 13 papers on asphyxia + WBH cases, a pattern of postnatal Scr trends in asphyxia + WBH cases was constructed. Compared to the reference 50th centile Scr values, mean or median Scr values at birth and up to 48 h were higher in asphyxia + WBH cases with a subsequent uncertain declining trend towards, at best, high or high-normal creatinine values afterwards. Such patterns are valuable for anticipating average changes in renal drug clearance but do not yet cover the relevant inter-patient variability observed in WBH cases, as this needs pooling of individual Screa profiles, preferably beyond the first week of life.