Early Use of Transcranial Doppler Ultrasonography to Stratify Neonatal Encephalopathy

BACKGROUND

The dynamic nature of neonatal hypoxic-ischemic encephalopathy (HIE) after birth necessitates reliable biomarkers to identify infants with evolving brain injury. This prospective cohort aims to use serial Doppler ultrasonography (US) to measure cerebral blood flow velocity and resistance index (RI) to help detect the time and evolution of the clinical encephalopathy.

METHODS

A total of 60 neonates were enrolled all ≥36 weeks' gestation with perinatal acidemia, defined as a blood gas pH ≤ 7.0 or base deficit ≥16 mmol/L and encephalopathy including a matched control group without encephalopathy. Each neonate received one to three serial Doppler recordings starting at six to 24 hours of life. Mean RI ≤ 0.55 was considered abnormal.

RESULTS

Mean RIs obtained shortly after birth were significantly lower with increasing severity of encephalopathy. On the first Doppler recordings, abnormal mean RIs were seen in 11 of 18 (61%) neonates with mild, 13 of 17 (76%) with moderate, and two of two (100%) with severe HIE. Of the neonates with mild HIE and abnormal mean RIs, congruity abnormal amplitude electroencephalography (45%), brain magnetic resonance imaging (45%), and abnormal head ultrasound (44%) are here reported.

CONCLUSIONS

Doppler measurements can provide bedside adjunct biomarkers indicating the time and severity of neonatal HIE.

Women receive less targeted temperature management than men following out-of-hospital cardiac arrest due to early care limitations - A study from the CARES Investigators

BACKGROUND

Women experience worse neurological outcomes following out-of-hospital cardiac arrest (OHCA). It is unknown whether sex disparities exist in the use of targeted temperature management (TTM), a standard of care treatment to improve neurological outcomes.

METHODS

We performed a retrospective study of prospectively collected patients who survived to hospital admission following OHCA from the Cardiac Arrest Registry to Enhance Survival from 2013 through 2019. We compared receipt of TTM by sex in a mixed-effects model adjusted for patient, arrest, neighborhood, and hospital factors, with the admitting hospital modeled as a random intercept.

RESULTS

Among 123,419 patients, women had lower rates of shockable rhythms (24.4 % vs. 39.2%, P < .001) and lower rates of presumed cardiac aetiologies for arrest (74.3% vs. 81.1%, P < .001). Despite receiving a similar rate of TTM in the field (12.1% vs. 12.6%, P = .02), women received less TTM than men upon admission to the hospital (41.6% vs. 46.4%, P < .001). In an adjusted mixed-effects model, women were less likely than men to receive TTM (Odds Ratio 0.91, 95% Confidence Interval 0.89 to 0.94). Among the 27,729 patients with data indicating the reason for not using TTM, a higher percentage of women did not receive TTM due to Do-Not-Resuscitate orders/family requests (15.1% vs. 11.4%, p < .001) and non-shockable rhythms (11.1% vs. 8.4%, p < .001).

CONCLUSIONS

We found that women received less TTM than men, likely due to early care limitations and a preponderance of non-shockable rhythms.

Tubular calcium, magnesium, and phosphate excretion during therapeutic hypothermia for neonatal hypoxic-ischemic encephalopathy: A prospective study

OBJECTIVES

Hypocalcemia, hypomagnesemia, and hyperphosphatemia are common electrolyte disturbances in perinatal asphyxia (PA). Different reasons have been proposed for these electrolyte disturbances. This study investigated the effect of the urinary excretion of calcium (Ca), magnesium (Mg), and phosphorus (P) on the serum levels of these substances in babies who were treated using therapeutic hypothermia for hypoxic ischemic encephalopathy (HIE) caused by PA. This study sheds light on the pathophysiology that may cause changes in the serum values of these electrolytes.

METHODS

This study included 21 healthy newborns (control group) and 38 patients (HIE group) who had undergone therapeutic hypothermia due to HIE. Only infants with a gestational age of 36 weeks and above and a birth weight of 2000 g and above were evaluated. The urine and serum Ca, Mg, P, and creatinine levels of all infants were evaluated at 24, 48, and 72 h.

RESULTS

The lower serum Ca value and the higher serum P value of the HIE group were found to be statistically significant compared to the control group (p<0.05). There was no significant difference in serum Mg values between the groups. However, hypomagnesemia was detected in five patients from the HIE group. The urine excretion of FeCa and FeMg at 24 h, and FeP excretion at 48 and 72 h were found to be significantly higher in the HIE group compared to the control group.

CONCLUSIONS

This study determined that the urinary excretion of Ca, Mg, and P has an effect on the serum Ca, Mg, and P levels of infants with HIE.

Update on mechanisms of the pathophysiology of neonatal encephalopathy

Therapeutic hypothermia is now well established to significantly improve survival without disability after neonatal encephalopathy (NE). To further improve outcomes, we need to better understand the mechanisms of brain injury. The central finding, which offers the potential for neuroprotective and neurorestorative interventions, is that brain damage after perinatal hypoxia-ischemia evolves slowly over time. Although brain cells may die during profound hypoxia-ischemia, even after surprisingly severe insults many cells show transient recovery of oxidative metabolism during a "latent" phase characterized by actively suppressed neural metabolism and activity. Critically, after moderate to severe hypoxia-ischemia, this transient recovery is followed after ~6 h by a phase of secondary deterioration, with delayed seizures, failure of mitochondrial function, cytotoxic edema, and cell death over ~72 h. This is followed by a tertiary phase of remodeling and recovery. This review discusses the mechanisms of injury that occur during the primary, latent, secondary and tertiary phases of injury and potential treatments that target one or more of these phases. By analogy with therapeutic hypothermia, treatment as early as possible in the latent phase is likely to have the greatest potential to prevent injury ("neuroprotection"). In the secondary phase of injury, anticonvulsants can attenuate seizures, but show limited neuroprotection. Encouragingly, there is now increasing preclinical evidence that late, neurorestorative interventions have potential to improve long-term outcomes.

Therapeutic hypothermia augments the restorative effects of PKC-β and Nox2 inhibition on an in vitro model of human blood-brain barrier

To investigate whether therapeutic hypothermia augments the restorative impact of protein kinase C-β (PKC-β) and Nox2 inhibition on an in vitro model of human blood-brain barrier (BBB). Cells cultured in normoglycaemic (5.5 mM) or hyperglycaemic (25 mM, 6 to 120 h) conditions were treated with therapeutic hypothermia (35 °C) in the absence or presence of a PKC-β inhibitor (LY333531, 0.05 μM) or a Nox2 inhibitor (gp91ds-tat, 50 μM). BBB was established by co-culture of human brain microvascular endothelial cells (HBMECs) with astrocytes (HAs) and pericytes. BBB integrity and function were assessed via transendothelial electrical resistance (TEER) and paracellular flux of sodium fluorescein (NaF, 376 Da). Nox activity (lucigenin assay), superoxide anion production (cytochrome-C reduction assay), cellular proliferative capacity (wound scratch assay) and actin cytoskeletal formation (rhodamine-phalloidin staining) were assessed both in HBMECs and HAs using the specific methodologies indicated in brackets. Therapeutic hypothermia augmented the protective effects of PKC-β or Nox2 inhibition on BBB integrity and function in experimental setting of hyperglycaemia, as evidenced by increases in TEER and concomitant decreases in paracellular flux of NaF. The combinatory approaches were more effective in repairing physical damage exerted on HBMEC and HA monolayers by wound scratch and in decreasing Nox activity and superoxide anion production compared to sole treatment regimen with either agent. Similarly, the combinatory approaches were more effective in suppressing actin stress fibre formation and maintaining normal cytoskeletal structure. Therapeutic hypothermia augments the cerebral barrier-restorative capacity of agents specifically targeting PKC-β or Nox2 pathways.

Therapies for neonatal encephalopathy: Targeting the latent, secondary and tertiary phases of evolving brain injury

In term and near-term neonates with neonatal encephalopathy, therapeutic hypothermia protocols are well established. The current focus is on how to improve outcomes further and the challenge is to find safe and complementary therapies that confer additional protection, regeneration or repair in addition to cooling. Following hypoxia-ischemia, brain injury evolves over three main phases (latent, secondary and tertiary), each with a different brain energy, perfusion, neurochemical and inflammatory milieu. While therapeutic hypothermia has targeted the latent and secondary phase, we now need therapies that cover the continuum of brain injury that spans hours, days, weeks and months after the initial event. Most agents have several therapeutic actions but can be broadly classified under a predominant action (e.g., free radical scavenging, anti-apoptotic, anti-inflammatory, neuroregeneration, and vascular effects). Promising early/secondary phase therapies include Allopurinol, Azithromycin, Exendin-4, Magnesium, Melatonin, Noble gases and Sildenafil. Tertiary phase agents include Erythropoietin, Stem cells and others. We review a selection of promising therapeutic agents on the translational pipeline and suggest a framework for neuroprotection and neurorestoration that targets the evolving injury.

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.

Unanswered questions regarding therapeutic hypothermia for neonates with neonatal encephalopathy

Therapeutic hypothermia (TH) is now well established to improve intact survival after neonatal encephalopathy (NE). However, many questions could not be addressed by the randomized controlled trials. Should late preterm newborns with NE be cooled? Is cooling beneficial for mild NE? Is the current therapeutic time window optimal, or could it be shortened or prolonged? Will either milder or deeper hypothermia be effective? Does infection/inflammation exposure in the perinatal period in combination with NE offer potentially beneficial preconditioning or might it obviate hypothermic neuroprotection? In the present review, we dissect the evidence, for whom, when and how can TH best be delivered, and highlight areas that need further research.

Neonatal infratentorial subdural hematoma contributing to obstructive hydrocephalus in the setting of therapeutic cooling: A case report

BACKGROUND

Symptomatic neonatal subdural hematomas usually result from head trauma incurred during vaginal delivery, most commonly during instrument assistance. Symptomatic subdural hematomas are rare in C-section deliveries that were not preceded by assisted delivery techniques. Although the literature is inconclusive, another possible cause of subdural hematomas is therapeutic hypothermia.

CASE SUMMARY

We present a case of a term neonate who underwent therapeutic whole-body cooling for hypoxic ischemic encephalopathy following an emergent C-section delivery for prolonged decelerations. Head ultrasound on day of life 3 demonstrated a rounded mass in the posterior fossa. A follow-up brain magnetic resonance imaging confirmed hypoxic ischemic encephalopathy and clarified the subdural hematomas in the posterior fossa causing mass effect and obstructive hydrocephalus.

CONCLUSION

The aim of this report is to highlight the rarity and importance of mass-like subdural hematomas causing obstructive hydrocephalus, particularly in the setting of hypoxic ischemic encephalopathy and therapeutic whole-body cooling.

Impact of Induced Therapeutic Hypothermia by Intravenous Infusion of Ice-Cold Fluids After Hospital Arrival in Comatose Survivors of Out-of-Hospital Cardiac Arrest With Initial Shockable Rhythm

BACKGROUND

The effect of in-hospital rapid cooling by intravenous ice-cold fluids for comatose survivors of out-of-hospital cardiac arrest (OHCA) is unclear.

METHODS AND RESULTS

From the J-PULSE-HYPO study registry, data for 248 comatose survivors with return of spontaneous circulation (ROSC) who were treated with therapeutic hypothermia (34℃ for 12-72 h) after witnessed shockable OHCA were extracted. Patients were divided into 2 groups by the median collapse-to-ROSC interval (18 min), and then into 2 groups by cooling method (rapid cooling by intravenous ice-cold fluids vs. standard cooling). The primary endpoint was favorable neurological outcome (Cerebral Performance Category of 1 or 2) at 30 days after OHCA. In the whole cohort, the shorter collapse-to-ROSC interval group had significantly higher favorable neurological outcome than the longer collapse-to-ROSC interval group (78.2% vs. 46.8%, P<0.001). In the shorter collapse-to-ROSC interval group, no significant difference was observed in favorable neurological outcome between the 2 cooling groups (rapid cooling group: 79.4% vs. standard cooling group: 77.0%, P=0.75). In the longer collapse-to-ROSC interval group, however, favorable neurological outcome was significant higher in the rapid cooling group than in the standard cooling group (60.7% vs. 33.3%, P<0.01) and the adjusted odds ratio after rapid cooling was 3.069 (95% confidence interval 1.423-6.616, P=0.004).

CONCLUSIONS

In-hospital rapid cooling by intravenous ice-cold fluids improved neurologically intact survival in comatose survivors whose collapse-to-ROSC interval was delayed over 18 min after shockable OHCA.

[Adherence to hypothermia guidelines in newborns with hypoxic-ischemic encephalopathy]

INTRODUCTION

We do not have population data in Spain on the application of therapeutic hypothermia (TH). The objective was to examine adherence to management standards during TH of infants with hypoxic-ischemic encephalopathy (HIE).

METHOD

Multicenter observational cohort study from the beginning of TH (year 2010) in 5 hospitals in a Spanish region, until year 2019.

RESULTS

133 patients were recruited, 72% diagnosed with moderate HIE and the rest of them with severe HIE. In 84% of infants, passive hypothermia was started at birth. Active TH was started at a median age of 5hours of life (IQR: 3.3-6.3), although the central targeted temperature (33-34°C) was reached at a median age of 3.5hours (IQR: 1-6). Those born extramural, initiated active TH 3.3hours on average later than those born intramural, but without differences in the age at which the targeted temperature was reached. Sedoanalgesia was used in 97%. The 100% were monitored with amplitude-integrated EEG and 59% with cerebral oxymetry. MRI was performed in 94% with moderate HIE vs. 65% with severe; P<.001. Neuron-specific enolase in cerebrospinal fluid was determined in 42%. The average duration of rewarming was median 10hours (IQR: 8-12), with no differences depending on the degree of HIE (P=.57).

CONCLUSIONS

The implementation of TH successfully met the standards. However, aspects of care that could be improved were detected. Auditing newborn care with HIE is crucial to achieving programs with a high quality of care in each region.

Targeted Temperature Management After Cardiac Arrest

and that reference citations are not used in the synopsis. A devastating complication of cardiac arrest is hypoxic-ischemic injury, which leads to neurologic dysfunction and subsequently high mortality. Post-cardiac arrest care is complex and requires a multimodal approach to manage hemodynamic instability as well as provide neuroprotection. Targeted temperature management is recommended by the American Heart Association as well as the International Liaison Committee on Resuscitation as a class 1 intervention for postarrest neuroprotection in patients who remain unresponsive after cardiac arrest.

Transrectal intracolon cooling prevents paraplegia and mortality in a rat model of aortic occlusion-induced spinal cord ischemia

OBJECTIVE

Spinal cord ischemia-reperfusion injury (SC-IRI) occurs in many medical conditions such as aneurysm surgical repair but no treatment of SC-IRI is available in clinical practice. The objective of the present study was to develop a novel medical device for the treatment of SC-IRI.

METHODS

A rat model of SC-IRI was used. A novel transrectal intracolon (TRIC) temperature management device was developed to maintain an intracolon wall temperature at either 37°C (TRIC37°C) or 12°C (TRIC12°C). The upper body temperature was maintained as close as possible to 37°C in both groups. A 2F Fogarty balloon catheter was inserted via the left common carotid artery to block the distal aortic blood flow to the spinal cord. The proximal blood pressure was controlled by the withdrawal and infusion of blood via the jugular vein catheter, such that the distal tail artery blood pressure was maintained at ∼10 mmHg for 13 and 20 minutes, respectively. Next, the balloon was deflated, and TRIC temperature management was continued for an additional 30 minutes to maintain the colon wall temperature at either 37°C or 12°C during the reperfusion period.

RESULTS

All the rats subjected to 13 minutes of spinal cord ischemia in the TRIC37°C group had developed paraplegia during the postischemic phase. In striking contrast, TRIC at 12°C completely prevented the paraplegia, dramatically improved the arterial blood gas parameters, and avoided the histopathologic injuries to the spinal cord in rats subjected to 13 minutes of spinal cord ischemia. Furthermore, TRIC12°C allowed for the extension of the ischemia duration from 13 minutes to 20 minutes, with significantly reduced functional deficits.

CONCLUSIONS

Directly cooling the intestine focally with the TRIC device offered an exceptional survival rate and functional improvement after aortic occlusion-induced spinal cord ischemia.

[Challenges in the application of non-servocontrolled therapeutic hypothermia during neonatal transport in Catalonia]

INTRODUCTION

Therapeutic hypothermia (TH) improves survival and neurological prognosis in hypoxic-ischemic encephalopathic (HIE) babies, being better the sooner TH is implemented. HIE babies are born more frequently in a non-cooling centre and need to be referred.

METHODS

Prospective-observational study (April 18-November 19). Newborns (≥34 weeks of gestational age (GA) and >1800g) with moderate/severe HIE on non-servocontrolled therapeutic hypothermia by the two neonatal transport teams in Catalonia.

RESULTS

51 newborns. The median stabilisation and transport time were 68min (p25-75, 45-85min) and 30min (p25-75, 15-45min), respectively. The mean age at arrival at the receiving unit was 4h and 18min (SD 96.6). The incubator was set off in 43 (84%), iced-packs 11 (21.5%) and both (11, 21.5%). Target temperature was reached in 19 (37.3%) babies. There was no differences in the overcooling in relation to the measures applied. The transport duration was not related with temperature stabilisation or target temperature reachiness.

CONCLUSIONS

Rectal temperature monitorisation is compulsory for the stabilisation and the application of non-servocontrolled hypothermia during transport. There is still time for improving in the administration of this treatment during transport. Servo-controlled hypothermia would be a better alternative to improve the management of HIE babies.

Subcutaneous fat necrosis associated with hypercalcemia in neonates with neonatal encephalopathy treated with therapeutic hypothermia

Subcutaneous fat necrosis of the newborn (SFNN) is a rare, self-resolving panniculitis. The onset of skins lesions occurs within the first week of life, with a median age of onset around day 6 of life (range 1-70). About 50% of neonates with SFNN will develop hypercalcemia in the first month though some present later. Typically, SFNN develops prior to hypercalcemia. Only half of the neonates have classic symptoms of hypercalcemia; routine screening for hypercalcemia is recommended for neonates with SFNN or at-risk. The mechanism for hypercalcemia is usually aberrant 1,25-dihydroxyvitamin D synthesis in the necrotic tissue increasing intestinal absorption of calcium. Prompt recognition and treatment is required, often in hospital. Treatment options are low calcium-vitamin D formula or sometimes intravenous bisphosphonates. Regular monitoring post-intervention is required when normalizing the diet. Outcomes are good with routine surveillance and interventions. A multidisciplinary team approach (neonatologists, pediatric endocrinologists and nephrologists, dieticians) is optimal.

Challenges in respiratory management during therapeutic hypothermia for neonatal encephalopathy

Neonatal encephalopathy (NE) is a serious condition with devastating neurological outcomes that can impact oxygenation and ventilation. The currently recommended therapeutic hypothermia (TH) for these infants may also has several respiratory implications. It decreases metabolic rate and oxygen demands; however, it increases oxygen solubility in the blood and impacts its release to peripheral tissue including the brain. Respiratory management of infants treated with TH should aim for minimizing exposure to hypocapnia or hyperoxia. Inspiratory gas should be heated to 37 °C and humidified to prevent airway and alveolar injury. Blood gas values should be corrected to the core temperature during TH and the use of alkaline buffers is discouraged. While mild sedation/analgesia may ameliorate the discomfort related to cooling, paralytic agents/heavy sedation should be used with caution considering their side effects. Finally, the use of caffeine still needs careful investigation in this population.

The Term Newborn: Evaluation for Hypoxic-Ischemic Encephalopathy

Neonatal encephalopathy due to perinatal hypoxia-ischemia (hypoxic-ischemic encephalopathy [HIE]) occurs at a rate of 1 to 3 per 1000 live births. Therapeutic hypothermia is the standard of care and the only currently available therapy to reduce the risk of death or disability in newborns with moderate to severe HIE. Hypothermia therapy needs to be initiated within 6 hours after birth in order to provide the best chance for neuroprotection. All pediatricians and delivery room attendants should be trained to recognize encephalopathy and understand the eligibility criteria for treatment. The modified Sarnat examination is the most frequently used tool to assess the degree of encephalopathy and has six categories, each of which can have mild, moderate, severe abnormalities. Apart from historical and biochemical criteria, a neonate must have 3 of 6 categories scored in the moderate or severe range in order to qualify for hypothermia as was done in the randomized trials. Whether an infant qualifies or there is concern that an infant might have HIE, transfer to a center that can perform treatment should be initiated immediately. Hypothermia significantly reduces the risk of death or moderate to severe impairments at 2 years and at school age. On average, only 7 neonates need to be treated for one neonate to benefit. Although easy in concept, implementation of hypothermia does require expertise and should be carried out under the guidance of a neonatologist. If infants are passively cooled prior to transport, core temperature needs to be closely monitored with a target of 33.5°C ± 0.5°C. Maintenance of homeostasis is important in order to prevent conditions that may result in additional brain injury. Seizures are common in neonates with HIE, but electrographic seizures are rare in the first few hours after birth if the insult occurred during labor and delivery. Prophylactic antiepileptic drugs should not be administered. Brain monitoring in the form of electroencephalogram (EEG) and or amplitude-integrated EEG should be implemented as soon as possible to help with prognosis and to accurately diagnose seizures.

Hypothermia for cardiogenic encephalopathy in neonates with dextro-transposition of the great arteries

OBJECTIVES

Neonates with dextro-transposition of the great arteries (d-TGA) may experience rapid haemodynamic deterioration and profound hypoxaemia after birth. We report on d-TGA patients with severe acidosis, encephalopathy and their treatment with systemic hypothermia.

METHODS

This study is a single-centre retrospective cohort analysis of newborns with d-TGA.

RESULTS

Ninety-five patients (gestational age ≥35 weeks) with d-TGA and intended arterial switch operation were included. Ten infants (10.5%) with umbilical arterial blood pH > 7.10 experienced profound acidosis (pH < 7.00) within the first 2 h of life. Six of these patients displayed signs of encephalopathy and received therapeutic hypothermia. Apgar scores at 5 min independently predicted the development of neonatal encephalopathy during postnatal transition (unit Odds Ratio 0.17, 95% confidence interval 0.06-0.49, P = 0.001). Infants treated with hypothermia had a more severe preoperative course and required more often mechanical ventilation (100% vs 35%, P = 0.003), treatment with inhaled nitric oxide (50% vs 2.4%, P = 0.002) and inotropic support (67% vs 3.5%, P < 0.001), as compared to non-acidotic controls. The median age at cardiac surgery was 12 (range 6-14) days in cooled infants and 8 (4-59) days in controls (P = 0.088). Postoperative morbidity and total duration of hospitalization were not increased in infants receiving preoperative hypothermia. Mortality in newborns with severe preoperative acidosis was zero.

CONCLUSIONS

Newborn infants with d-TGA have a substantial risk for profound acidosis during the first hours of life. Systemic hypothermia for encephalopathic patients may delay corrective surgery without compromising perioperative outcomes.

Repolarization and ventricular arrhythmia during targeted temperature management post cardiac arrest

BACKGROUND

Targeted temperature management (TTM) following out-of-hospital cardiac arrest (OHCA) prolongs the QT-interval but our knowledge of different temperatures and risk of arrhythmia is incomplete.

OBJECTIVE

To assess whether the QTc, QT-peak (QTp) and T-peak to T-end interval (TpTe) may be useful markers of ventricular arrhythmia in contemporary post cardiac arrest treatment.

METHODS

An ECG-substudy of the TTM-trial (TTM at 33 °C vs. 36 °C) with serial ECGs from 680 (94%) patients. Bazett's (B) and Fridericia's (F) formula were used for heart rate correction of the QT, QTp and TpTe. Ventricular arrhythmia (VT/VF) were registered during the first three days of post cardiac arrest care.

RESULTS

The QT, QTc and QTp intervals were prolonged more at 33 °C compared to 36 °C and restored to similar and lower levels after rewarming. The TpTe-interval remained between 92-100 ms throughout TTM in both groups. The QTc intervals were associated with ventricular arrhythmia, but not after adjustment for cardiac arrest characteristics. The QTp-interval was not associated with risk of ventricular arrhythmia. Heart rate corrected TpTe-intervals were associated with higher risk of arrhythmia (Odds ratio (OR): TpTe(B): 1.12 (1.02-1.23, p = 0.01 TpTe(F): 1.12 (1.02-1.23, p = 0.02) per 20 ms). Further a prolonged TpTe-interval ≥ 90 ms was consistently associated with higher risk (OR_adjusted: TpTe(B): 2.05 (1.25-3.37), p < 0.01, TpTe(F): 2.14 (1.32-3.49), p < 0.01).

CONCLUSIONS

TTM prolongs the QT-interval by prolongation of the QTp-interval without association to increased risk. The TpTe-interval is not significantly affected by core temperature, but heart rate corrected TpTe intervals are robustly associated with risk of ventricular arrhythmia.

TRIAL REGISTRATION

The TTM-trial is registered and accessible at ClinicalTrials.gov (Identifier: NCT01020916).

Neonatal hypoxic-ischemic encephalopathy diagnosis and treatment: a National Survey in China

Background

Neonatal hypoxic-ischemic encephalopathy (HIE) affects as many as 100,000 infants each year in China. Therapeutic hypothermia reduces HIE related mortality and long-term neurodevelopmental disabilities. National guidelines for HIE management were published a decade ago. This study aimed to investigate the current status of HIE diagnosis and treatment in China.

Method

This prospective cross-sectional national survey used a questionnaire evaluating practices related to HIE management. Descriptive statistics and Chi-square or Fisher’s exact test were used, and a p-value of < 0.05 was considered significant.

Results

The 273 hospitals that completed the survey were located in 31 of the 34 provincial districts in China. Eighty-eight percent of the hospitals were Level III hospitals, and 74% treated 10 or more HIE cases annually. Awareness rates of the national guidelines for HIE diagnosis, HIE treatment, and therapeutic hypothermia protocol were 85, 63, and 78%, respectively. Neurological manifestations and blood gas were used as HIE diagnostic criteria by 96% (263/273) and 68% (186/273) of the hospitals, respectively. Therapeutic hypothermia was used in 54% (147/273) of hospitals. The percentage of general hospitals that implemented therapeutic hypothermia (43%, 71/165) was significantly lower than that in maternity and infant hospitals (67%, 49/73) (χ² = 11.752, p = 0.001) and children’s hospitals (77%, 27/35) (χ² = 13.446, p < 0.001). Reasons for not providing therapeutic hypothermia included reduction of HIE cases in recent years (39%), high cost of cooling devices and treatment (31%), lack of training (26%), and safety concerns (4%). Among the hospitals that provided therapeutic hypothermia, 27% (39/147) were in full compliance with the recommended protocol. Eighty-one percent (222/273) of the hospitals treated HIE infants with putative neuroprotective agents alone or in combination with cooling. Ninety-one percent of the hospitals had long-term neurodevelopmental follow-up programs for infants with HIE.

Conclusions

There is significant heterogeneity in HIE diagnosis and treatment in China. Therapeutic hypothermia has not become a standard of care for neonatal HIE nationwide. Unproven agents are widely used for HIE treatment. Nationwide standardization of HIE management and dissemination of therapeutic hypothermia represent the opportunities to reduce mortality and improve long-term neurodevelopmental outcomes of children affected by HIE.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-021-02737-6.

Cooling in mild encephalopathy: Costs and perils of therapeutic creep

Increasing confidence in therapeutic hypothermia and ambiguity of cooling guidelines has led to many clinicians extending its use to untested populations like mild encephalopathy, or even no encephalopathy. Poor quality clinical neurological examination for encephalopathy staging coupled with a fear of litigation if a baby with mild encephalopathy progress to moderate or severe encephalopathy appears to be the primary driver for this therapeutic creep. Recent data suggesting increased apoptosis with cooling uninjured brains, and lack of hypothermic neuroprotection in partial prolonged hypoxia, implies that such therapeutic creeps may cause more harm than benefit. Currently available preclinical and clinical data do not support the clinical use of therapeutic hypothermia for mild encephalopathy, although phase II clinical trials are ongoing. We recommend that until further evidence from adequately powered randomised controlled trials are available, cooling in mild encephalopathy need to be considered experimental and parental consent should be obtained before providing this therapy.

MRI combined with early clinical variables are excellent outcome predictors for newborn infants undergoing therapeutic hypothermia after perinatal asphyxia

BACKGROUND

Binary prediction-models for outcome [death, cognition, presence and severity of cerebral palsy (CP)], using MRI and early clinical data applicable for individual outcome prediction have not been developed.

METHODS

From Dec 1st 2006 until Dec 31st 2013, we recruited 178 infants into a population-based cohort with moderate or severe hypoxic-ischaemic encephalopathy (HIE) including postnatal collapse (PNC, n = 12) and additional diagnoses (n = 12) using CoolCap/TOBY-trial entry-criteria including depressed amplitude-integrated EEG (aEEG). Early clinical/biochemical variables and MRI scans (median day 8) were obtained in 168 infants. Injury severity was scored for cortex, basal ganglia/thalami (BGT), white matter (WM) and posterior limb of the internal capsule, summating to a total injury score (TIS, range 0-11). Outcome was categorized as adverse or favourable at 18-24 months from Bayley-III domains (cut-off 85) and neurological examination including CP classification.

FINDINGS

HIE and entry-aEEG severity were stable throughout the study. Outcome was favourable in 133/178 infants and adverse in 45/178: 17 died, 28 had low Cognition/Language scores, (including 9 with severe CP and 6 mild); seven had mild CP with favourable cognitive outcome. WMxBGT product scores and TIS were strong outcome predictors, and prediction improved when clinical/biochemical variables were added in binary logistic regression. The Positive Predictive Value for adverse outcome was 88%, increasing to 95% after excluding infants with PNC and additional diagnoses. Using WMxBGT in the regression predicted 8 of the 9 children with severe CP.

INTERPRETATION

Binary logistic regression with WMxBGT or TIS and clinical variables gave excellent outcome prediction being 12% better than single variable cross-tabulation. Our MRI scoring and regression models are readily accessible and deserve investigation in other cohorts for group and individual prediction.

FUNDING

We thank the National Health Service (NHS) and our Universities and funders in UK and Norway: SPARKS, The Moulton Foundation, The Norwegian Research Council, The Lærdal Foundation for Acute Medicine and charitable donations for their support for cooling therapy.

Temperature Variability Does Not Attenuate the Beneficial Effects of Therapeutic Hypothermia on Cellular Apoptosis and Endoplasmic Reticulum Stress in the Cerebral Cortex of a Swine Cardiac Arrest Model

BACKGROUND

Endoplasmic reticulum stress (ERS) plays a vital role in mediating apoptosis in the brain following cardiac arrest (CA). Studies have shown that therapeutic hypothermia (TH) provides neuroprotection through anti-apoptosis; however, the effects of temperature variability in TH on the brain remain unclear. In this study, we investigated the different effects of temperature variability through extracorporeal membrane oxygenation on apoptosis and ERS in the brain following CA.

METHODS

Eighteen male domestic pigs underwent 6-min duration of no-flow induced by ventricular fibrillation. Extracorporeal cardiopulmonary resuscitation was then performed, and the return of spontaneous circulation (ROSC) was achieved. The animals were randomly assigned to the following groups: normothermia, non-temperature variability, and temperature variability. TH (core temperature, 33-35 °C) was maintained for 24 h post-ROSC, and the animals were rewarmed for 8 h. Quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry for Bax and Bcl-2 transcripts and proteins, respectively, were used to investigate apoptosis in the cerebral cortex. Expression levels of the ERS molecules, GRP78 and CHOP, were also detected by qRT-PCR, and cellular morphology was evaluated using transmission electron microscopy.

RESULTS

qRT-PCR and immunohistochemistry results revealed that TH significantly increased the expression levels of Bcl-2 and GRP78 and decreased that of Bax and CHOP than under normothermia conditions. Compared to the non-temperature variability group, temperature variability did not decrease the expression levels of Bcl-2 and GRP78 and not increase the levels of Bax and CHOP. Endoplasmic reticulum ultrastructural changes were significantly improved under TH. No statistical difference was observed between the temperature variability and non-temperature variability groups.

CONCLUSION

TH can reduce neuronal apoptosis by ERS, while temperature variability does not attenuate this beneficial effect.

Cardiac arrest caused by accidental severe hypothermia and myocardial infarction during general anesthesia

Therapeutic hypothermia is often used for traumatic brain injury because of its neuroprotective effect and decreased secondary brain injury. However, this procedure lacks clinical evidence supporting its efficacy, and adverse outcomes have been reported during general anesthesia. A 61-year-old man with a history of percutaneous coronary intervention (PCI) was admitted with traumatic brain injury. Immediately after admission, he underwent mild therapeutic hypothermia with a target temperature of 33.0°C for neuroprotection. During general anesthesia for emergency surgery because he developed a mass effect, hypothermic cardiac arrest occurred following an additional decrease in the core body temperature. Moreover, myocardial infarction caused by restenosis of the previous PCI lesion also contributed to the cardiac arrest. Although the patient recovered spontaneous circulation after an hour-long cardiopulmonary resuscitation with rewarming, he eventually died of subsequent repetitive cardiac arrests. When anesthetizing patients undergoing therapeutic hypothermia, caution is required to prevent adverse outcomes that can be caused by unintentional severe hypothermia and exacerbation of underlying heart disease.