Comparison of selective head cooling versus whole-body cooling

Is Selective Head Cooling Combined with Whole-Body Cooling the Most Effective Hypothermia Method for Neonatal Hypoxic-Ischemic Encephalopathy?

This study aimed to compare combined hypothermia (CH) to the 2 classical therapeutic hypothermia (TH) methods selective head cooling (SHC) and whole-body cooling (WBC). This retrospective cohort study included neonates who underwent CH, SHC, and WBC between 2012 and 2020. Mean rectal temperature was maintained at 33.5 ± 0.5°C by cooling the head and the body in the CH group, at 34.5 ± 0.5°C by cooling the head in the SHC group, and at 33.5 ± 0.5°C by cooling the body in the WBC group. The groups were compared in terms of side effects, magnetic resonance imaging (MRI) scores, and status at discharge. The study included 60 neonates in the CH group, 112 in the WBC group, and 27 in the SHC group. There was no significant difference in side effects between the groups (p > 0.05). There was no significant difference in brain MRI scores between the groups (p > 0.05); however, gray matter, white matter, and total MRI scores in the CH group were lower than in the WBC group. Duration of hospitalization was shorter in the CH group than in the other two groups (p = 0.022). CH was not associated with more side effects than the two classical TH methods. In addition, some of these findings suggest that CH might result in better clinical outcome than the two classical TH methods.

Use of Cranial Ultrasound Prior to the Start of Therapeutic Hypothermia for Newborn Encephalopathy

For a precise diagnosis of infant hypoxic-ischemic encephalopathy (HIE), neuroimaging is required. The nature and time of the brain injury, the imaging modalities used, and the timing of their application all affect the therapeutic usefulness of neuroimaging in neonatal HIE. Most neonatal intensive care units (NICUs) across the world have access to cranial ultrasound (cUS), a safe, low-cost piece of technology that may be used at the patient's bedside. Infants undergoing active therapeutic hypothermia (TH) must undergo a cUS to be screened for intracranial hemorrhage (ICH), according to the clinical practice guidelines. The guidelines advise brain cUS on days 4 and 10-14 of life after hypothermia therapy is finished in order to thoroughly assess the nature and severity of any brain impairment. Early cUS is meant to rule out major ICH, which is listed in the local guideline for TH as a relative exclusion factor. This study questions whether cUS should be a required screening method before the start of TH.

Administration of selective brain hypothermia using a simple cooling device in neonatal rats

BACKGROUND

The interruption of oxygen and blood supply to the newborn brain around the time of birth is a risk factor for hypoxic-ischemic encephalopathy and may lead to infant mortality or lifelong neurological impairments. Currently, therapeutic hypothermia, the cooling of the infant's head or entire body, is the only treatment to curb the extent of brain damage.

NEW METHOD

In this study, we designed a focal brain cooling device that circulates cooled water at a steady state temperature of 19 ± 1 °C through a coil of tubing fitted onto the neonatal rat's head. We tested its ability to selectively decrease brain temperature and offer neuroprotection in a neonatal rat model of hypoxic-ischemic brain injury.

RESULTS

Our method cooled the brain to 30-33 °C in conscious pups, while keeping the core body temperature approximately 3.2 °C warmer. Furthermore, the application of the cooling device to the neonatal rat model demonstrated a reduction in brain volume loss compared to pups maintained at normothermia and achieved a level of brain tissue protection the same as that of whole-body cooling.

COMPARISON WITH EXISTING METHODS

Prevailing methods of selective brain hypothermia are designed for adult animal models rather than for immature animals such as the rat as a conventional model of developmental brain pathology. Contrary to existing methods, our method of cooling does not require surgical manipulation or anaesthesia.

CONCLUSION

Our simple, economical, and effective method of selective brain cooling is a useful tool for rodent studies in neonatal brain injury and adaptive therapeutic interventions.

Hypothermia combined with neuroprotective adjuvants shortens the duration of hospitalization in infants with hypoxic ischemic encephalopathy: Meta-analysis

Objective: Therapeutic hypothermia (TH) is the current standard of care for neonatal hypoxic-ischemic encephalopathy (HIE), yet morbidity and mortality remain significant. Adjuvant neuroprotective agents have been suggested to augment hypothermic-mediated neuroprotection. This analysis aims to identify the classes of drugs that have been used in combination with hypothermia in the treatment of neonatal HIE and determine whether combination therapy is more efficacious than TH alone. Methods: A systematic search of PubMed, Embase and Medline from conception through December 2022 was conducted. Randomized- and quasi-randomized controlled trials, observational studies and retrospective studies evaluating HIE infants treated with combination therapy versus TH alone were selected. Primary reviewers extracted information on mortality, neurodevelopmental impairment and length of hospitalization for meta-analyses. Effect sizes were pooled using a random-effects model and measured as odds ratio (OR) or mean difference (MD) where applicable, and 95% confidence intervals (CI) were calculated. Risk of bias was assessed using the tool from the Cochrane Handbook for Systematic Reviews of Interventions. Results: The search strategy collected 519 studies, 16 of which met analysis inclusion criteria. HIE infants totaled 1,288 infants from included studies, 646 infants received some form of combination therapy, while 642 received TH alone. GABA receptor agonists, NMDA receptor antagonists, neurogenic and angiogenic agents, stem cells, glucocorticoids and antioxidants were identified as candidate adjuvants to TH that have been evaluated in clinical settings compared to TH alone. Length of hospitalization was significantly reduced in infants treated with combination therapy (MD -4.81, 95% CI [-8.42. to -1.19], p = .009) compared to those treated with TH alone. Risk of mortality and neurodevelopmental impairment did not differ between combination therapy and TH alone groups. Conclusion: Compared to the current standard of care, administration of neuroprotective adjuvants with TH reduced the duration of hospitalization but did not impact the risk of mortality or neurodevelopmental impairment in HIE infants. Meta-analysis was limited by a moderate risk of bias among included studies and small sample sizes. This analysis highlights the need for preclinical trials to conduct drug development studies in hypothermic settings to identify relevant molecular targets that may offer additive or synergistic neuroprotection to TH, and the need for larger powered clinical trials to determine the dose and timing of administration at which maximal clinical benefits are observed for adjuvant neuroprotectants.

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.

Treatment and new progress of neonatal hypoxic-ischemic brain damage

Neonatal hypoxic ischemia (HI) results in different extents of brain damage, and immature brain tissue is particularly sensitive to the stimulation of HI. Hypoxic-ischemic brain damage (HIBD) is a common and serious nervous system disease in neonates, for both full-term infants and preterm infants, and is one of the main causes of neonatal death. The surviving infants are often associated with cerebral palsy, mental retardation, and other sequelae, which severely affect quality of life. For term infants, hypoxia and ischemia mainly affect gray matter, whereas in preterm infants, the white matter. However, up to now, inadequate standards and specific measures that can be used to treat hypoxic-ischemic brain injury are available. Recently, in addition to supportive therapy and symptomatic treatment, research on the treatment of hypoxic-ischemic brain injury has focused on the following aspects: hypothermia therapy, stem cell therapy, neuroprotective agents, ibuprofen, and combination therapy. In this review, we will summarize the treatment of HIBD and make suggestions for the future treatment direction.

Oropharyngeal Dysphagia in Breastfeeding Neonates with Hypoxic-Ischemic Encephalopathy on Therapeutic Hypothermia

Purpose: To identify symptoms of oropharyngeal dysphagia (OPD) in breastfeeding neonates with hypoxic-ischemic encephalopathy (HIE) on therapeutic hypothermia (TH). Early identification of feeding problems in neonates with HIE by speech-language therapists (SLTs) may prevent secondary complications of OPD such as aspiration pneumonia and death. Materials and Methods: Twenty-eight full-term neonates with HIE (mean chronological age = 4.5 days) and 30 healthy term controls were prospectively recruited for this case-control study. Participants with HIE (mild [n = 15], moderate [n = 11], severe [n = 2]), diagnosed by pediatricians, received whole-body TH. Feeding was clinically evaluated by an SLT using the Preterm Infant Breastfeeding Behavior Scale. Results: Twenty-five neonates (89.2%) had at least one symptom of OPD. Falling asleep during feeding, noticeable oral secretions, coughing, and flaring nostrils were symptoms of OPD most frequently identified. The HIE group displayed limited arousal during breastfeeding and had less obvious rooting, shallower latching onto the breast, and more single sucks in comparison to term newborns. The HIE group had significantly more closed eyes and minimal movement during breastfeeding, while controls showed the quiet-alert state ideal for breastfeeding. Conclusions: OPD was identified in the majority of infants with HIE. Underlying the appearance of an inactive neonate with HIE may be OPD that could be overlooked if not investigated. Interprofessional collaboration between SLTs, pediatricians and nurses to determine feeding-readiness is imperative. SLTs may assist in decision-making to improve safety of breastfeeding in this population. This study contributes to the small body of research on early breastfeeding of neonates with HIE.

Selective head cooling and whole body cooling as neuroprotective agents in severe perinatal asphyxia

INTRODUCTION

The possibility that hypothermia has a therapeutic role during or after resuscitation from severe perinatal asphyxia has been a longstanding focus of research. Studies designed around this fact have shown that moderate cerebral hypothermia, initiated as early as possible, has been associated with potent, long-lasting neuroprotection in perinatal patients.

OBJECTIVES

To review the benefits of hypothermia in improving cellular function, based on the cellular characteristics of hypoxic-ischemic cerebral injury and compare the results of two different methods of cooling the brain parenchyma.

METHODS

Medline, Lilacs, Scielo, and PubMed were searched for articles registered between 1990 and 2019 in Portuguese and English, focused on trials comparing the safety and effectiveness of total body cooling with selective head cooling with HIE.

RESULTS

We found that full-body cooling provides homogenous cooling to all brain structures, including the peripheral and central regions of the brain. Selective head cooling provides a more extensive cooling to the cortical region of the brain than to the central structures.

CONCLUSIONS

Both methods demonstrated to have neuroprotective properties, although full-body cooling provides a broader area of protection. Recently, head cooling combined with some body cooling has been applied, which is the most promising approach. The challenge for the future is to find ways of improving the effectiveness of the treatment.

Neuroprotection by Therapeutic Hypothermia

Hypothermia therapy is an old and important method of neuroprotection. Until now, many neurological diseases such as stroke, traumatic brain injury, intracranial pressure elevation, subarachnoid hemorrhage, spinal cord injury, hepatic encephalopathy, and neonatal peripartum encephalopathy have proven to be suppressed by therapeutic hypothermia. Beneficial effects of therapeutic hypothermia have also been discovered, and progress has been made toward improving the benefits of therapeutic hypothermia further through combination with other neuroprotective treatments and by probing the mechanism of hypothermia neuroprotection. In this review, we compare different hypothermia induction methods and provide a summarized account of the synergistic effect of hypothermia therapy with other neuroprotective treatments, along with an overview of hypothermia neuroprotection mechanisms and cold/hypothermia-induced proteins.

Neonatal Encephalopathy: Current Management and Future Trends

It is well-documented in the literature that infants who suffer from hypoxic ischemic encephalopathy are at high risk for neurologic sequelae or even death. With the addition of therapeutic hypothermia into the treatment regimen for neonatal hypoxic ischemic encephalopathy, newborns afflicted with hypoxic ischemic encephalopathy were given the opportunity for a better outcome. Questions linger as to the most optimal treatment strategy of therapeutic hypothermia for these newborns. The goal of this article is to discuss current management strategies, as well as future trends, for infants with hypoxic ischemic encephalopathy.

Turkish Neonatal Society Guideline on neonatal encephalopathy

Neonatal encephalopathy is a major cause of neonatal mortality and morbidity. Therapeutic hypothermia is standard treatment for newborns at 35 weeks of gestation or more with intrapartum hypoxia-related neonatal encephalopathy. Term and late preterm infants with moderate-to-severe encephalopathy show improved survival and neurodevelopmental outcomes at 18 months of age after therapeutic hypothermia. Therapeutic hypothermia can increase survival without increasing major disability. Neonates with severe neonatal encephalopathy remain at risk of death or severe neurodevelopmental impairment. This guideline was prepared by the Turkish Neonatal Society to standardize the management of neonatal encephalopathy throughout the country.

Hypothermia for newborns with hypoxic-ischemic encephalopathy

Therapeutic hypothermia is a standard of care for infants ≥36 weeks gestational age (GA) with moderate-to-severe hypoxic-ischemic encephalopathy. Because some studies included infants born at 35 weeks GA, hypothermia should be considered if they meet other criteria. Cooling for infants <35 weeks GA is not recommended. Passive cooling should be started promptly in community centres, in consultation with a tertiary care centre neonatologist, while closely monitoring the infant's temperature. Best evidence suggests that maintaining core body temperature between 33°C and 34°C for 72 hours, followed by a period of rewarming of 6 to 12 hours, is optimal. Antiepileptic medications should be used when clinical or electrographic seizures are present. Maintaining serum electrolytes and glucose within normal ranges, and avoiding hypo- or hypercarbia and hyperoxia, are important adjunct treatments. A brain magnetic resonance image (MRI) is advised shortly after rewarming and, in cases where earlier findings do not match the clinical picture, a repeat MRI after 10 days of life is suggested. Multidisciplinary neurodevelopmental follow-up is recommended.

Therapeutic hypothermia for neonates with hypoxic ischemic encephalopathy

Therapeutic hypothermia (TH) is a recommended regimen for newborn infants who are at or near term with evolving moderate-to-severe hypoxic ischemic encephalopathy (HIE). The Task Force of the Taiwan Child Neurology Society and the Taiwan Society of Neonatology held a joint meeting in 2015 to establish recommendations for using TH on newborn patients with HIE. Based on current evidence and experts' experiences, this review article summarizes the key points and recommendations regarding TH for newborns with HIE, including: (1) selection criteria for TH; (2) choices of method and equipment for TH; (3) TH prior to and during transport; (4) methods for temperature maintenance, monitoring, and rewarming; (5) systemic care of patients during TH, including the care of respiratory and cardiovascular systems, management of fluids, electrolytes, and nutrition, as well as sedation and drug metabolism; (6) monitoring and management of seizures; (7) neuroimaging, prognostic factors, and outcomes; and (8) adjuvant therapy for TH.

Servo controlled versus manual cooling methods in neonates with hypoxic ischemic encephalopathy

BACKGROUND

Therapeutic hypothermia is known to improve outcomes in neonates with hypoxic ischemic encephalopathy (HIE). There are no studies that have compared servo controlled cooling (SCC) versus manually controlled cooling (MCC) methods in HIE.

AIM

To compare the outcomes of SCC versus MCC in neonates with HIE.

METHODS AND OUTCOME MEASURES

Between Jan 2008 and May 2011, MCC with cool-gel packs was used to achieve rectal temperatures of 33.5 to 34.5°C in our units. Subsequently, we changed to SCC to achieve rectal temperatures of 33 to 34°C. 105 neonates received SCC whereas 95 received MCC. Retrospective study with multivariate analysis was conducted comparing thermoregulation (primary outcome) and neurodevelopmental outcomes of SCC versus MCC.

RESULTS

In the SCC group, 72.3% had stage 2 or 3 HIE versus 77.9% in the MCC. The remaining had stage 1, but attending neonatologists decided to provide cooling. Prescribed rectal temperatures were achieved in 80.5% (5768/7168) instances in SCC versus 72.9% (4449/6108) in MCC (p<0.0001). There were no significant differences in the incidence of 'death or moderate-severe disability' [SCC 26/85 vs MCC 26/87, adjusted odds ratio: 1.29, 95% CI: 0.48, 3.42; p=0.614]. The results were similar after excluding stage 1 HIE [SCC 25/66 vs MCC 26/69, adjusted odds ratio: 1.01, 95% CI: 0.50, 2.02; p=0.981].

CONCLUSIONS

SCC resulted in better thermoregulation in neonates undergoing therapeutic hypothermia. There were no significant differences in neurodevelopmental outcomes, but the study was underpowered to answer this. Randomized trials are needed to fine-tune various aspects of TH in neonates with HIE.