Postnatal phenobarbital for the prevention of intraventricular haemorrhage in preterm infants.

BACKGROUND: Intraventricular haemorrhage (IVH) is a major complication of preterm birth. Large haemorrhages are associated with a high risk of disability and hydrocephalus. Instability of blood pressure and cerebral blood in the newborn flow are postulated as causative factors. Another mechanism may involve reperfusion damage from oxygen free radicals. It has been suggested that phenobarbital stabilises blood pressure and may protect against free radicals. This is an update of a review first published in 2001 and updated in 2007 and 2013. OBJECTIVES: To assess the benefits and harms of the postnatal administration of phenobarbital in preterm infants at risk of developing IVH compared to control (i.e. no intervention or placebo). SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL), Medline, Embase, CINAHL and clinical trial registries in January 2022. A new, more sensitive search strategy was developed, and searches were conducted without date limits.  SELECTION CRITERIA: We included randomised controlled trials (RCTs) or quasi-RCTs in which phenobarbital was given within the first 24 hours of life to preterm infants identified as being at risk of IVH because of gestational age below 34 weeks, birth weight below 1500 g or respiratory failure. Phenobarbital was compared to no intervention or placebo. We excluded infants with serious congenital malformations. DATA COLLECTION AND ANALYSIS: We used standard Cochrane methods. Our primary outcomes were all grades of IVH and severe IVH (i.e. grade III and IV); secondary outcomes were ventricular dilation or hydrocephalus, hypotension, pneumothorax, hypercapnia, acidosis, mechanical ventilation, neurodevelopmental impairment and death. We used GRADE to assess the certainty of the evidence for each outcome. MAIN RESULTS: We included 10 RCTs (792 infants). The evidence suggests that phenobarbital results in little to no difference in the incidence of IVH of any grade compared with control (risk ratio (RR) 1.00, 95% confidence interval (CI) 0.84 to 1.19; risk difference (RD) 0.00, 95% CI -0.06 to 0.07; I² for RD = 65%; 10 RCTs, 792 participants; low certainty evidence) and in severe IVH (RR 0.88, 95% CI 0.64 to 1.21; 10 RCTs, 792 participants; low certainty evidence). The evidence is very uncertain about the effect of phenobarbital on posthaemorrhagic ventricular dilation or hydrocephalus (RR 0.62, 95% CI 0.31 to 1.26; 4 RCTs, 271 participants; very low certainty evidence), mild neurodevelopmental impairment (RR 0.57, 95% CI 0.15 to 2.17; 1RCT, 101 participants; very low certainty evidence), and severe neurodevelopmental impairment (RR 1.12, 95% CI 0.44 to 2.82; 2 RCTs, 153 participants; very low certainty evidence). Phenobarbital may result in little to no difference in death before discharge (RR 0.88, 95% CI 0.64 to 1.21; 9 RCTs, 740 participants; low certainty evidence) and mortality during study period (RR 0.98, 95% CI 0.72 to 1.33; 10 RCTs, 792 participants; low certainty evidence) compared with control. We identified no ongoing trials. AUTHORS' CONCLUSIONS: The evidence suggests that phenobarbital results in little to no difference in the incidence of IVH (any grade or severe) compared with control (i.e. no intervention or placebo). The evidence is very uncertain about the effects of phenobarbital on ventricular dilation or hydrocephalus and on neurodevelopmental impairment. The evidence suggests that phenobarbital results in little to no difference in death before discharge and all deaths during the study period compared with control. Since 1993, no randomised studies have been published on phenobarbital for the prevention of IVH in preterm infants, and no trials are ongoing. The effects of postnatal phenobarbital might be assessed in infants with both neonatal seizures and IVH, in both randomised and observational studies. The assessment of benefits and harms should include long-term outcomes.

The feasibility of using a portable xenon delivery device to permit earlier xenon ventilation with therapeutic cooling of neonates during ambulance retrieval.

BACKGROUND: Therapeutic hypothermia is the standard of care after perinatal asphyxia. Preclinical studies show 50% xenon improves outcome, if started early. METHODS: During a 32-patient study randomized between hypothermia only and hypothermia with xenon, 5 neonates were given xenon during retrieval using a closed-circuit incubator-mounted system. RESULTS: Without xenon availability during retrieval, 50% of eligible infants exceeded the 5-hour treatment window. With the transportable system, 100% were recruited. Xenon delivery lasted 55 to 120 minutes, using 174 mL/h (117.5-193.2) (median [interquartile range]), after circuit priming (1300 mL). CONCLUSIONS: Xenon delivery during ambulance retrieval was feasible, reduced starting delays, and used very little gas.

Cooling neonates who do not fulfil the standard cooling criteria - short- and long-term outcomes.

AIM: Therapeutic hypothermia is effective and without serious adverse effects in term infants with hypoxic-ischaemic encephalopathy. It is unknown whether other neonatal patient groups could benefit from therapeutic hypothermia. Since 2006, our centre has offered cooling to infants fulfilling the standard cooling criteria, but also to those who did not. METHODS: Observational study with prospective data collection over a 6-year period in a regional cooling centre. Complications and outcome were compared between infants who were cooled not fulfilling the standard inclusion and exclusion criteria as set out in the CoolCap/TOBY protocol (n = 36) and infants who fulfilled the standard entry criteria (n = 129). RESULTS: 21.8% of cooled infants did not fulfil standard cooling entry criteria. This included infants cooled >6 postnatal hours, late preterm infants, and infants with postnatal collapse, major cranial haemorrhage, congenital cardiac disease and surgical conditions. Complication rates and long-term outcome did not differ significantly between the groups, apart from in infants with a major cranial haemorrhage, who had higher rates of coagulopathy and the worst outcome (80% death/disability). CONCLUSION: Cooling can be considered for infants with neonatal encephalopathy following postnatal collapse or preterm birth, those with underlying surgical or cardiac conditions, and infants starting cooling >6 postnatal hours.

Less severe cerebral palsy outcomes in infants treated with therapeutic hypothermia.

AIM: To describe the incidence, type and severity of cerebral palsy at 24 months in a regional cohort of infants treated with whole-body therapeutic hypothermia for neonatal encephalopathy. METHODS: Data were collected prospectively in a regional centre providing TH. Antenatal and perinatal clinical variables and severity of encephalopathy were collected. Infants were assessed at 18 months using the Bayley Scales of Infant and Toddler Development-III, and the presence and severity of CP was investigated at 24 months. RESULTS: A total of 125 of 132 infants fulfilled entry criteria for TH trials and completed 72 h of TH. Sixteen (13%) of the 125 infants died, and eight (6%) were not available for follow-up. Eighteen infants (14%; 18% of those assessed) developed CP. Of these, 12 (67%) were classified using the Gross Motor Function Classification System, at level 1, six (33%) at level 5 and none at levels 2, 3 or 4. CONCLUSION: Our regional clinical cohort had lower mortality and comparable rates of CP compared with historical outcomes in TH trials. In contrast to historical cohorts, only one-third of the 18 children with CP were severely affected and 12 were mildly affected, all of whom were independently ambulant by 24 months.

Equipotent subanesthetic concentrations of sevoflurane and xenon preventing cold-stimulated vocalization of neonatal rats.

BACKGROUND: The effects of inhaled anesthetics on the developing brain are studied using neonatal rodents exposed to fractions of minimum alveolar concentration (to avoid cardiorespiratory compromise). However, these fractions cannot be assumed to be equipotent. Xenon's anesthetic and neuroprotective properties warrant investigation in these models. Therefore, equipotent, subanesthetic concentrations of inhaled anesthetics are needed. METHODS: Forty-eight Wistar rats (Charles River Laboratories, Kent, United Kingdom) on postnatal day 9 were randomized to eight concentrations of inhaled anesthetics: isoflurane, sevoflurane, or xenon. Exposure was closely monitored in individual metal-based chambers resting on a 35°C mat to maintain normothermia. A 25°C mat was used to stimulate vocalization and a sound recording made (1 min, 1 to 100 kHz). Rectal temperature or partial pressure of carbon dioxide and pH of mixed arteriovenous blood were measured immediately after the exposure. Concentration-response models were constructed using logistic regression (dependent variable: vocalization and explanatory variable: concentration). The effects of all other explanatory variables were assessed by inserting them individually into the model. RESULTS: The effective inhaled concentrations preventing cold-stimulated vocalization in 50 and 95% of neonatal rats (EiC50 and EiC95) on postnatal day 9 were 0.46 and 0.89% sevoflurane and 20.15 and 34.81% xenon, respectively. The effect on the EiC50 of all other explanatory variables, including duration, was minimal. Stability of EiC50 isoflurane was not achieved over three durations (40, 80, and 120 min exposure). Partial pressure of carbon dioxide and pH in mixed arteriovenous blood appeared normal. CONCLUSIONS: The authors report equipotent subanesthetic concentrations of sevoflurane and xenon in neonatal rats with preserved cardiopulmonary function. This may be useful in designing neonatal rodent models of anesthesia.

Factors associated with permanent hearing impairment in infants treated with therapeutic hypothermia.

OBJECTIVE: To define the incidence of hearing impairment, document plasma gentamicin concentrations, and identify factors associated with permanent hearing impairment in infants subjected to therapeutic hypothermia for moderate or severe neonatal encephalopathy. STUDY DESIGN: Data were collected prospectively in a regional center providing therapeutic hypothermia. Cooled infants at ≥ 36 weeks gestation with moderate or severe neonatal encephalopathy were analyzed if a full dataset was available (n = 108), including clinical variables and gentamicin trough levels. Infants with hearing impairment were identified, and survivors were followed up with neurodevelopmental evaluation at age 18 months. Stepwise logistic regression identified factors associated with hearing impairment. RESULTS: Nine infants died, and among the survivors, 10.1% developed a permanent hearing impairment. The trough gentamicin level was above the recommended cutoff of 2 mg/L in 37% of the infants in the entire cohort and in 90% of the infants with hearing impairment. Logistic regression analysis identified high trough gentamicin level, low cord pH, and hypoglycemia (<46.8 mg/dL) in the first postnatal hour as significantly associated with hearing impairment. The need for inotropic support was close to significant (P = .055). CONCLUSION: Hearing impairment was a common finding among cooled infants. Plasma gentamicin levels were commonly >2 mg/L. Based on these findings, we propose changes in gentamicin dosing interval and trough level monitoring to minimize the risk of potentially toxic levels in cooled newborns.

Postnatal phenobarbital for the prevention of intraventricular haemorrhage in preterm infants.

BACKGROUND: Intraventricular haemorrhage (IVH) is a major complication of preterm birth. Large haemorrhages are associated with a high risk of disability and hydrocephalus. Instability of blood pressure and cerebral blood flow are postulated as causative factors. Another mechanism may involve reperfusion damage from oxygen free radicals. Phenobarbital has been suggested as a safe treatment that stabilises blood pressure and may protect against free radicals. OBJECTIVES: To determine the effect of postnatal administration of phenobarbital on the risk of IVH, neurodevelopmental impairment or death in preterm infants. SEARCH METHODS: We used the search strategy of the Neonatal Collaborative Review Group. The original review author (A Whitelaw) was an active trialist in this area and had personal contact with many groups in this field. He handsearched journals from 1976 (when cranial computed tomography (CT) scanning started) to October 2000; these included: Pediatrics, Journal of Pediatrics, Archives of Disease in Childhood, Pediatric Research, Developmental Medicine and Child Neurology, Acta Paediatrica, European Journal of Pediatrics, Neuropediatrics, New England Journal of Medicine, Lancet and British Medical Journal. We searched the National Library of Medicine (USA) database (via PubMed) and the Cochrane Central Register of Controlled Trials (CENTRAL, 2012, Issue 10) through to 31 October 2012. We did not limit the searches to the English language, as long as the article included an English abstract. We read identified articles in the original language or translated. SELECTION CRITERIA: We included randomised or quasi-randomised controlled trials in which phenobarbital was given to preterm infants identified as being at risk of IVH because of gestational age below 34 weeks, birthweight below 1500 g or respiratory failure. Adequate determination of IVH by ultrasound or CT was also required. DATA COLLECTION AND ANALYSIS: In addition to details of patient selection and control of bias, we extracted the details of the administration of phenobarbital. We searched for the following endpoints: IVH (with grading), posthaemorrhagic ventricular dilation or hydrocephalus, neurodevelopmental impairment and death. In addition, we searched for possible adverse effects of phenobarbitone, for example hypotension, mechanical ventilation, pneumothorax, hypercapnia and acidosis. MAIN RESULTS: We included 12 controlled trials that recruited 982 infants. There was heterogeneity between trials for the outcome IVH, with three trials finding a significant decrease in IVH and one trial finding an increase in IVH in the group receiving phenobarbital. Meta-analysis showed no difference between the phenobarbital-treated group and the control group in either all IVH (typical risk ratio (RR) 0.91; 95% CI 0.77 to 1.08), severe IVH (typical RR 0.77; 95% CI 0.58 to 1.04), posthaemorrhagic ventricular dilation (typical RR 0.89; 95% CI 0.38 to 2.08), severe neurodevelopmental impairment (typical RR 1.44; 95% CI 0.41 to 5.04) or death before hospital discharge (typical RR 0.88; 95% CI 0.64 to 1.21). There was a consistent trend in the trials towards increased use of mechanical ventilation in the phenobarbital-treated group, which was supported by the meta-analysis (typical RR 1.18; 95% CI 1.06 to 1.32; typical risk difference 0.129; 95% CI 0.04 to 0.21), but there was no significant difference in pneumothorax, acidosis or hypercapnia. AUTHORS' CONCLUSIONS: Postnatal administration of phenobarbital cannot be recommended as prophylaxis to prevent IVH in preterm infants and is associated with an increased need for mechanical ventilation.

The effectiveness of interventions to prevent intraventricular haemorrhage in premature infants: A systematic review and network meta-analysis.

BACKGROUND: Intraventricular haemorrhage (IVH) is a common problem in preterm infants, being a major cause of morbidity and mortality. Despite many randomised controlled trials comparing interventions to prevent IVH, the best prevention remains unclear. This study aims to review all the interventions which intended to reduce the incidence of IVH and compare them in a network meta-analysis. METHODS: A search on MEDLINE, EMBASE, Emcare, and CENTRAL was performed. Randomised controlled trials which evaluated neonatal interventions with a primary aim to reduce incidence of IVH in preterm infants were eligible. A surface under a cumulative ranking curve (SUCRA) was produced to indicate the intervention's likelihood of being the most effective for preventing IVH. RESULTS: 40 studies were eligible, enrolling over 6760 infants. Twelve intervention groups were found, including delayed cord clamping, erythropoietin, ethamsylate, fresh frozen plasma, heparin, ibuprofen, indomethacin, magnesium, nursing interventions, sedation, tranexamic acid, and vitamin E. Vitamin E and indomethacin had the highest probability of being the best interventions to prevent IVH in premature infants, but interpretation of these results is difficult due to study limitations. CONCLUSION: Despite the impact of IVH, we were unable to identify a clearly beneficial treatment to reduce its incidence. Interpretation of the network meta-analysis was limited due to differences within studied populations, wide range of therapies trialled, and underlying advances in neonatal care between units, and over time. Although vitamin E and indomethacin appear to be promising candidates, contemporaneous trials of these, or novel agents, enrolling the most at-risk infants is needed urgently.

nSeP: immune and metabolic biomarkers for early detection of neonatal sepsis-protocol for a prospective multicohort study.

INTRODUCTION: Diagnosing neonatal sepsis is heavily dependent on clinical phenotyping as culture-positive body fluid has poor sensitivity, and existing blood biomarkers have poor specificity.A combination of machine learning, statistical and deep pathway biology analyses led to the identification of a tripartite panel of biologically connected immune and metabolic markers that showed greater than 99% accuracy for detecting bacterial infection with 100% sensitivity. The cohort study described here is designed as a large-scale clinical validation of this previous work. METHODS AND ANALYSIS: This multicentre observational study will prospectively recruit a total of 1445 newborn infants (all gestations)-1084 with suspected early-or late-onset sepsis, and 361 controls-over 4 years. A small volume of whole blood will be collected from infants with suspected sepsis at the time of presentation. This sample will be used for integrated transcriptomic, lipidomic and targeted proteomics profiling. In addition, a subset of samples will be subjected to cellular phenotype and proteomic analyses. A second sample from the same patient will be collected at 24 hours, with an opportunistic sampling for stool culture. For control infants, only one set of blood and stool sample will be collected to coincide with clinical blood sampling. Along with detailed clinical information, blood and stool samples will be analysed and the information will be used to identify and validate the efficacy of immune-metabolic networks in the diagnosis of bacterial neonatal sepsis and to identify new host biomarkers for viral sepsis. ETHICS AND DISSEMINATION: The study has received research ethics committee approval from the Wales Research Ethics Committee 2 (reference 19/WA/0008) and operational approval from Health and Care Research Wales. Submission of study results for publication will involve making available all anonymised primary and processed data on public repository sites. TRIAL REGISTRATION NUMBER: NCT03777670.

Monitoring of cerebral blood flow during hypoxia-ischemia and resuscitation in the neonatal rat using laser speckle imaging.

Neonatal hypoxic-ischemic encephalopathy (HIE) is associated with alterations in cerebral blood flow (CBF) as a result of perinatal asphyxia. The extent to whichCBFchanges contribute to injury, and whether treatments that ameliorate these changes might be neuroprotective, is still unknown. Higher throughput techniques to monitorCBFchanges in rodent models ofHIEcan help elucidate the underlying pathophysiology. We developed a laser speckle imaging (LSI) technique to continuously monitorCBFin six postnatal-day 10 (P10) rats simultaneously before, during, and after unilateral hypoxia-ischemia (HI, ligation of the left carotid artery followed by hypoxia in 8% oxygen). After ligation,CBFto the ligated side fell by 30% compared to the unligated side (P < 0.0001). Hypoxia induced a bilateral 55% reduction inCBF, which was partially restored by resuscitation. Compared to resuscitation in air, resuscitation in 100% oxygen increasedCBFto the ligated side by 45% (P = 0.033). Individual variability inCBFresponse to hypoxia between animals accounted for up to 24% of the variability in hemispheric area loss to the ligated side. In both P10 and P7 models of unilateralHI, resuscitation in 100% oxygen did not affect hemispheric area loss, or hippocampalCA1 pyramidal neuron counts, after 1-week survival. ContinuousCBFmonitoring usingLSIin multiple rodents simultaneously can screen potential treatment modalities that affectCBF, and provide insight into the pathophysiology ofHI.

The effect of resuscitation in 100% oxygen on brain injury in a newborn rat model of severe hypoxic-ischaemic encephalopathy.

AIM: Infants with birth asphyxia frequently require resuscitation. Current guidance is to start newborn resuscitation in 21% oxygen. However, infants with severe hypoxia-ischaemia may require prolonged resuscitation with oxygen. To date, no study has looked at the effect of resuscitation in 100% oxygen following a severe hypoxic-ischaemic insult. METHODS: Postnatal day 7 Wistar rats underwent a severe hypoxic-ischaemic insult (modified Vannucci unilateral brain injury model) followed by immediate resuscitation in either 21% or 100% oxygen for 30 min. Seven days following the insult, negative geotaxis testing was performed in survivors, and the brains were harvested. Relative ipsilateral cortical and hippocampal area loss was assessed histologically. RESULTS: Total area loss in the affected hemisphere and area loss within the hippocampus did not significantly differ between the two groups. The same results were seen for short-term neurological assessment. No difference was seen in weight gain between pups resuscitated in 21% and 100% oxygen. CONCLUSION: Resuscitation in 100% oxygen does not cause a deleterious effect on brain injury following a severe hypoxic-ischaemic insult in a rat model of hypoxia-ischaemia. Further work investigating the effects of resuscitation in 100% oxygen is warranted, especially for newborn infants with severe hypoxic-ischaemic encephalopathy.

Combined treatment of xenon and hypothermia in newborn rats--additive or synergistic effect?

BACKGROUND: Breathing the inert gas Xenon (Xe) enhances hypothermic (HT) neuroprotection after hypoxia-ischemia (HI) in small and large newborn animal models. The underlying mechanism of the enhancement is not yet fully understood, but the combined effect of Xe and HT could either be synergistic (larger than the two effects added) or simply additive. A previously published study, using unilateral carotid ligation followed by hypoxia in seven day old (P7) rats, showed that the combination of mild HT (35°C) and low Xe concentration (20%), both not being neuroprotective alone, had a synergistic effect and was neuroprotective when both were started with a 4 h delay after a moderate HI insult. To examine whether another laboratory could confirm this finding, we repeated key aspects of the study. DESIGN/METHODS: After the HI-insult 120 pups were exposed to different post-insult treatments: three temperatures (normothermia (NT) NT37°C, HT35°C, HT32°C) or Xe concentrations (0%, 20% or 50%) starting either immediately or with a 4 h delay. To assess the synergistic potency of Xe-HT, a second set (n = 101) of P7 pups were exposed to either HT35°C+Xe0%, NT+Xe20% or a combination of HT35°C+Xe20% starting with a 4 h delay after the insult. Brain damage was analyzed using relative hemispheric (ligated side/unligated side) brain tissue area loss after seven day survival. RESULTS: Immediate HT32°C (p = 0.042), but not HT35°C significantly reduced brain injury compared to NT37°C. As previously shown, adding immediate Xe50% to HT32°C increased protection. Neither 4 h-delayed Xe20%, nor Xe50% at 37°C significantly reduced brain injury (p>0.050). In addition, neither 4 h-delayed HT35°C alone, nor HT35°C+Xe20% reduced brain injury. We found no synergistic effect of the combined treatments in this experimental model. CONCLUSIONS: Combining two treatments that individually were ineffective (delayed HT35°C and delayed Xe20%) did not exert neuroprotection when combined, and therefore did not show a synergistic treatment effect.

Sedation management during therapeutic hypothermia for neonatal encephalopathy: atropine premedication for endotracheal intubation causes a prolonged increase in heart rate.

AIM: Heart rate (HR) plays an important role in the assessment of stress during therapeutic hypothermia (TH) for neonatal encephalopathy; we aimed to quantify the effect on HR of endotracheal (ET) intubation and drugs given to facilitate it. If atropine premedication independently increased HR, the main indicator of effective sedation, we hypothesised that increased sedation would have been given. METHODS: Thirty-two, term, neonates recruited into a randomised pilot study comparing TH and TH combined with 50% Xenon inhalation were studied. Indications for ET intubation included: resuscitation at delivery, clinical need and elective re-intubation with a cuffed ET tube if randomised to Xenon. Standard intubation drugs comprised one or more of intravenous morphine, atropine, and suxamethonium. Local cooling guidelines were followed including morphine infusion for sedation. RESULTS: At postnatal hours five to eight atropine increased HR in a linear regression model (p<0.01). All other independent variables were excluded. Where more than one dose of atropine was given total morphine sedation given up to 8h into the treatment period was significantly higher (p<0.01). CONCLUSION: We have shown that atropine premedication for ET intubation significantly increased HR, the main indicator of effective sedation and total morphine dose for sedation during early TH was increased where more than one dose of atropine was given. Bradycardia was not reported in any neonate, even without atropine premedication. We suggest that the use of atropine as part of standard premedication for ET intubation of term neonates undergoing TH should be reconsidered.