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1.  Safety and efficacy of topiramate in neonates with hypoxic ischemic encephalopathy treated with hypothermia (NeoNATI) 
BMC Pediatrics  2012;12:144.
Despite progresses in neonatal care, the mortality and the incidence of neuro-motor disability after perinatal asphyxia have failed to show substantial improvements. In countries with a high level of perinatal care, the incidence of asphyxia responsible for moderate or severe encephalopathy is still 2–3 per 1000 term newborns. Recent trials have demonstrated that moderate hypothermia, started within 6 hours after birth and protracted for 72 hours, can significantly improve survival and reduce neurologic impairment in neonates with hypoxic-ischemic encephalopathy. It is not currently known whether neuroprotective drugs can further improve the beneficial effects of hypothermia. Topiramate has been proven to reduce brain injury in animal models of neonatal hypoxic ischemic encephalopathy. However, the association of mild hypothermia and topiramate treatment has never been studied in human newborns. The objective of this research project is to evaluate, through a multicenter randomized controlled trial, whether the efficacy of moderate hypothermia can be increased by concomitant topiramate treatment.
Term newborns (gestational age ≥ 36 weeks and birth weight ≥ 1800 g) with precocious metabolic, clinical and electroencephalographic (EEG) signs of hypoxic-ischemic encephalopathy will be randomized, according to their EEG pattern, to receive topiramate added to standard treatment with moderate hypothermia or standard treatment alone. Topiramate will be administered at 10 mg/kg once a day for the first 3 days of life. Topiramate concentrations will be measured on serial dried blood spots. 64 participants will be recruited in the study. To evaluate the safety of topiramate administration, cardiac and respiratory parameters will be continuously monitored. Blood samplings will be performed to check renal, liver and metabolic balance. To evaluate the efficacy of topiramate, the neurologic outcome of enrolled newborns will be evaluated by serial neurologic and neuroradiologic examinations. Visual function will be evaluated by means of behavioural standardized tests.
This pilot study will explore the possible therapeutic role of topiramate in combination with moderate hypothermia. Any favourable results of this research might open new perspectives about the reduction of cerebral damage in asphyxiated newborns.
Trial registration
Current Controlled Trials ISRCTN62175998; Identifier NCT01241019; EudraCT Number 2010-018627-25
PMCID: PMC3478965  PMID: 22950861
Neonatal hypoxic-ischemic encephalopathy; Therapeutic hypothermia; Topiramate
2.  Pharmacokinetics of dexmedetomidine combined with therapeutic hypothermia in a piglet asphyxia model 
The highly selective α2-adrenoreceptor agonist, dexmedetomidine, exerts neuroprotective, analgesic, anti-inflammatory and sympatholytic properties that may be beneficial for perinatal asphyxia. The optimal safe dose for pre-clinical newborn neuroprotection studies is unknown.
Following cerebral hypoxia-ischaemia, dexmedetomidine was administered to nine newborn piglets in a de-escalation dose study in combination with hypothermia (whole body cooling to 33.5°C). Dexmedetomidine was administered with a loading dose of 1 μg/kg and maintenance infusion at doses from 10 to 0.6 μg/kg/h. One additional piglet was not subjected to hypoxia-ischaemia. Blood for pharmacokinetic analysis was sampled pre-insult and frequently post-insult. A one-compartment linear disposition model was used to fit data. Population parameter estimates were obtained using non-linear mixed effects modelling.
All dexmedetomidine infusion regimens led to plasma concentrations above those associated with sedation in neonates and children (0.4–0.8 μg/l). Seven out of the nine piglets with hypoxia-ischaemia experienced periods of bradycardia, hypotension, hypertension and cardiac arrest; all haemodynamic adverse events occurred in piglets with plasma concentrations greater than 1 μg/l. Dexmedetomidine clearance was 0.126 l/kg/h [coefficient of variation (CV) 46.6.%] and volume of distribution was 3.37 l/kg (CV 191%). Dexmedetomidine clearance was reduced by 32.7% at a temperature of 33.5°C. Dexmedetomidine clearance was reduced by 55.8% following hypoxia-ischaemia.
Dexmedetomidine clearance was reduced almost tenfold compared with adult values in the newborn piglet following hypoxic-ischaemic brain injury and subsequent therapeutic hypothermia. Reduced clearance was related to cumulative effects of both hypothermia and exposure to hypoxia. High plasma levels of dexmedetomidine were associated with major cardiovascular complications.
PMCID: PMC4171780  PMID: 24724965
3.  Perinatal asphyxia 
BMJ Clinical Evidence  2007;2007:0320.
In resource-rich countries, the incidence of severe perinatal asphyxia (causing death or severe neurological impairment) is about 1/1000 live births. In resource-poor countries, perinatal asphyxia is probably much more common. Data from hospital-based studies in such settings suggest an incidence of 5–10/1000 live births.
Methods and outcomes
We conducted a systematic review and aimed to answer the following clinical question: What are the effects of interventions in term or near-term newborns with perinatal asphyxia? We searched: Medline, Embase, The Cochrane Library and other important databases up to June 2006 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).
We found 25 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.
In this systematic review we present information relating to the effectiveness and safety of the following interventions: anticonvulsants (prophylactic), antioxidants, calcium channel blockers, corticosteroids, fluid restriction, head and/or whole body hypothermia, hyperbaric oxygen treatment, hyperventilation, inotrope support, magnesium sulphate, mannitol, opiate antagonists, and resuscitation (in air versus higher concentrations of oxygen).
Key Points
Estimates of the incidence of perinatal asphyxia vary. In resource-rich countries, severe perinatal asphyxia (causing death or severe neurological impairment) is 1/1000 live births; in resource-poor countries, studies suggest an incidence of 5–10/1000 live births.
Limited evidence from three small, weak RCTs suggests that mortality may be lower in infants treated with antioxidants compared with placebo.
There is limited evidence that hypothermia reduces mortality and neurodevelopmental disability in infants with perinatal asphyxia.
Limited evidence from one small RCT suggests that a magnesium sulphate/dopamine combination may be more effective than no treatment in reducing a combined outcome of mortality, abnormal scans, and failure to feed.
Small RCTs with flawed methods suggest that anticonvulsants are of no benefit in reducing mortality or improving neurodevelopmental outcomes in term infants with perinatal asphyxia.
Resuscitation in air lowered mortality in infants with perinatal asphyxia compared with resuscitation in 100% oxygen. However, current clinical practice is to use 100% oxygen.
Limited evidence from a systematic review that reported problems with publication bias in the RCTs it identified suggests that hyperbaric oxygen treatment lowers rates of mortality and adverse neurological outcomes in infants with perinatal asphyxia and hypoxic–ischaemic encephalopathy. This treatment, although widely used in China, is not standard practice in other countries.
We don't know whether calcium channel blockers, corticosteroids, fluid restriction, hyperventilation, inotrope support, mannitol, or opiate antagonists are helpful in infants with perinatal asphyxia.
PMCID: PMC2943784  PMID: 19450354
4.  Effect of Temperature on Thromboelastography (TEG) and Implications for Clinical Use in Neonates Undergoing Therapeutic Hypothermia 
Pediatric research  2014;75(5):663-669.
Encephalopathic neonates undergoing therapeutic hypothermia have increased risk for coagulopathy secondary to perinatal asphyxia and effects of cooling on the coagulation enzyme cascade. Thromboelastography (TEG) allows for a comprehensive assessment of coagulation that can be regulated for temperature. TEG has not been previously evaluated in newborns undergoing hypothermia treatment.
Encephalopathic neonates treated with systemic hypothermia were enrolled in this prospective observational study. Daily blood specimens were collected for standard coagulation tests and platelet counts during hypothermia and after rewarming. Concurrent TEG assays were performed at 33.5°C and 37.0°C for comparison.
A total of 48 paired TEGs from 24 subjects were performed. Mean (± SD) birthweight was 3.2±0.7 Kg, gestational age 38.4±1.4 weeks, and 40% were male. TEG results differed significantly between assays performed at 37.0°C versus 33.5°C, indicating more impaired coagulation at 33.5°C. TEG parameters K, α, MA and CI were significantly associated with clinical bleeding (p<0.05). These remained significant (except for MA) after controlling for transfusion therapy.
TEG results are affected by temperature, consistent with the known association of hypothermia with coagulopathy. Several TEG parameters are predictive of clinical bleeding in newborns undergoing hypothermia. Selected cutpoints to predict bleeding risk are temperature dependent.
PMCID: PMC3992188  PMID: 24522100
5.  Physiologic and pharmacologic considerations for hypothermia therapy in neonates 
With mounting evidence that hypothermia is neuroprotective in newborns with hypoxic-ischemic encephalopathy (HIE), an increasing number of centers are offering this therapy. Hypothermia is associated with a wide range of physiologic changes affecting every organ system, and awareness of these effects is essential for optimum patient management. Lowering the core temperature also alters pharmacokinetic and pharmacodynamic properties of medications commonly used in asphyxiated neonates, necessitating close attention to drug efficacy and side effects. Rewarming introduces additional risks and challenges as the hypothermia-associated physiologic and pharmacologic changes are reversed. In this review we provide an organ system-based assessment of physiologic changes associated with hypothermia. We also summarize evidence from randomized controlled trials showing lack of serious adverse effects of moderate hypothermia therapy in term and near-term newborns with moderate-to-severe HIE. Finally, we review the effects of hypothermia on drug metabolism and clearance based on studies in animal models and human adults, and limited data from neonates.
PMCID: PMC3552186  PMID: 21183927
hypothermia; hypoxic-ischemic encephalopathy; neonate; pharmacologic effect; physiology effect; rewarming
Critical care medicine  2013;41(10):2379-2387.
Preclinical and clinical studies have suggested that therapeutic hypothermia, while decreasing neurological injury, may also lead to drug toxicity that may limit its benefit. Cooling decreases cytochrome p450(CYP)-mediated drug metabolism and limited clinical data suggest that drug levels are elevated. Fosphenytoin is metabolized by CYP2C, has a narrow therapeutic range, and is a commonly used antiepileptic medication. The objective of the study was to evaluate the impact of therapeutic hypothermia on phenytoin levels and pharmacokinetics in children with severe TBI.
Pharmacokinetic analysis of subjects participating in a multicenter randomized Phase III study of therapeutic hypothermia for severe TBI.
Intensive care unit at the Children’s Hospital of Pittsburgh
Nineteen children with severe TBI.
Measurements and Main Results
A total of 121 total and 114 free phenytoin levels were evaluated retrospectively in 10 hypothermia- and 9 normothermia-treated children who were randomized to 48h of cooling to 32–33°C followed by slow rewarming or controlled normothermia. Drug dosing, body temperatures, and demographics were collected during cooling, rewarming, and post-treatment periods(8 days). A trend towards elevated free phenytoin levels in the hypothermia group(p=0.051) to a median of 2.2 mg/L during rewarming was observed and was not explained by dosing differences. Nonlinear mixed effects modeling incorporating both free and total levels demonstrated that therapeutic hypothermia specifically decreased the time-variant component of the maximum velocity of phenytoin metabolism(Vmax) 4.6-fold(11.6 to 2.53 mg/h) and reduced the overall Vmax by ~50%. Simulations showed that the increased risk for drug toxicity extends many days beyond the end of the cooling period.
Therapeutic hypothermia significantly reduces phenytoin elimination in children with severe TBI leading to increased drug levels for an extended period of time after cooling. Pharmacokinetic interactions between hypothermia and medications should be considered when caring for children receiving this therapy.
PMCID: PMC3783553  PMID: 23896831
children; drug metabolism; hypothermia; phenytoin; pharmacokinetics; traumatic brain injury
7.  Selective head cooling for the treatment of neurologic complications of acute liver failure in a newborn with disseminated herpes infection 
SpringerPlus  2013;2:572.
Neurologic complications of pediatric acute liver failure (ALF) are a major determinant of outcome. Management of these complications, including increased intracranial pressure (ICP) is largely supportive. Although hypothermia is an effective treatment for perinatal asphyxia and is used to reduce ICP following traumatic brain injury, it has not been evaluated for neurologic complications of ALF in the newborn.
Case report.
We present a case of neonatal herpes simplex virus (HSV)-associated ALF with profound neurologic impairment and increased ICP. The patient was treated with selective head cooling, and monitored with transcranial doppler (TCD) studies of cerebral blood flow velocity, and electroencephalograms (EEG). The duration of head cooling was influenced by absent diastolic flow on TCDs, which subsequently improved during hypothermia. Continuous EEGs captured subclinical seizures, which improved with antiepileptic medications. Her death was attributed to a massive pulmonary hemorrhage and a hypoxemic cardiac arrest secondary to significant coagulopathy.
This case demonstrates that selective head cooling may attenuate increased ICP in neonatal encephalopathy, and that TCDs may guide management in the absence of invasive monitoring.
PMCID: PMC3825224  PMID: 24255865
Acute liver failure; Transcranial doppler; EEG; Neonate; Hypothermia
8.  Erythropoietin for Neuroprotection in Neonatal Encephalopathy: Safety and Pharmacokinetics 
Pediatrics  2012;130(4):683-691.
To determine the safety and pharmacokinetics of erythropoietin (Epo) given in conjunction with hypothermia for hypoxic-ischemic encephalopathy (HIE). We hypothesized that high dose Epo would produce plasma concentrations that are neuroprotective in animal studies (ie, maximum concentration = 6000–10 000 U/L; area under the curve = 117 000–140 000 U*h/L).
In this multicenter, open-label, dose-escalation, phase I study, we enrolled 24 newborns undergoing hypothermia for HIE. All patients had decreased consciousness and acidosis (pH < 7.00 or base deficit ≥ 12), 10-minute Apgar score ≤ 5, or ongoing resuscitation at 10 minutes. Patients received 1 of 4 Epo doses intravenously: 250 (N = 3), 500 (N = 6), 1000 (N = 7), or 2500 U/kg per dose (N = 8). We gave up to 6 doses every 48 hours starting at <24 hours of age and performed pharmacokinetic and safety analyses.
Patients received mean 4.8 ± 1.2 Epo doses. Although Epo followed nonlinear pharmacokinetics, excessive accumulation did not occur during multiple dosing. At 500, 1000, and 2500 U/kg Epo, half-life was 7.2, 15.0, and 18.7 hours; maximum concentration was 7046, 13 780, and 33 316 U/L, and total Epo exposure (area under the curve) was 50 306, 131 054, and 328 002 U*h/L, respectively. Drug clearance at a given dose was slower than reported in uncooled preterm infants. No deaths or serious adverse effects were seen.
Epo 1000 U/kg per dose intravenously given in conjunction with hypothermia is well tolerated and produces plasma concentrations that are neuroprotective in animals. A large efficacy trial is needed to determine whether Epo add-on therapy further improves outcome in infants undergoing hypothermia for HIE.
PMCID: PMC3457622  PMID: 23008465
neonatal encephalopathy; asphyxia; hypoxia-ischemia; neuroprotection
9.  Hypothermia for hypoxic–ischemic encephalopathy 
Moderate to severe hypoxic–ischemic injury in newborn infants, manifested as encephalopathy immediately or within hours after birth, is associated with a high risk of either death or a lifetime with disability. In recent multicenter clinical trials, hypothermia initiated within the first 6 postnatal hours has emerged as a therapy that reduces the risk of death or impairment among infants with hypoxic–ischemic encephalopathy. Prior to hypothermia, no therapies directly targeting neonatal encephalopathy secondary to hypoxic–ischemic injury had convincing evidence of efficacy. Hypothermia therapy is now becoming increasingly available at tertiary centers. Despite the deserved enthusiasm for hypothermia, obstetric and neonatology caregivers, as well as society at large, must be reminded that in the clinical trials more than 40% of cooled infants died or survived with impairment. Although hypothermia is an evidence-based therapy, additional discoveries are needed to further improve outcome after HIE. In this article, we briefly present the epidemiology of neonatal encephalopathy due to hypoxic–ischemic injury, describe the rationale for the use of hypothermia therapy for hypoxic–ischemic encephalopathy, and present results of the clinical trials that have demonstrated the efficacy of hypothermia. We also present findings noted during and after these trials that will guide care and direct research for this devastating problem.
PMCID: PMC2897079  PMID: 20625441
HIE; hyperthermia; hypothermia; hypoxic–ischemic encephalopathy; neonate; perinatal asphyxia
10.  Gentamicin Pharmacokinetics in Neonates Undergoing Therapeutic Hypothermia 
Therapeutic drug monitoring  2013;35(2):217-222.
To identify whether therapeutic hypothermia in newborns with hypoxic ischemic encephalopathy affects gentamicin pharmacokinetics.
Study Design
Retrospective case–control study consisting of 16 neonates who underwent therapeutic hypothermia and received gentamicin with interpretable peak and trough serum levels obtained during the period of cooling and at steady state; comparator group consisting of 7 neonates met the criteria but did not undergo therapeutic hypothermia.
Significant differences in gentamicin pharmacokinetics were noted between the therapeutic hypothermia group and the comparator group in elimination rate constant (0.08/h versus 0.11/h; P < 0.01), elimination half-life (9.16 hours versus 6.56 hours; P < 0.01), and clearance (0.04 L/kg.h−1 versus 0.05 L/kg.h−1; P < 0.01), respectively. Higher gentamicin trough serum concentrations were seen with the therapeutic hypothermia group (1.68 mcg/mL versus 0.77 mcg/mL; P < 0.01).
Therapeutic hypothermia is associated with alterations in gentamicin pharmacokinetics, reducing gentamicin clearance by 25.5% in neonates with hypoxic ischemic encephalopathy, which may result in increased trough serum concentrations.
PMCID: PMC4000311  PMID: 23503448
hypoxic ischemic encephalopathy; cooling; aminoglycoside
11.  The Practice of Therapeutic Hypothermia after Cardiac Arrest in France: A National Survey 
PLoS ONE  2012;7(9):e45284.
Cardiac arrest is a major health concern worldwide accounting for 375,000 cases per year in Europe with a survival rate of <10%. Therapeutic hypothermia has been shown to improve patients’ neurological outcome and is recommended by scientific societies. Despite these guidelines, different surveys report a heterogeneous application of this treatment. The aim of the present study was to evaluate the clinical practice of therapeutic hypothermia in cardiac arrest patients.
This self-declarative web based survey was proposed to all registered French adult intensive care units (ICUs) (n = 357). Paediatrics and neurosurgery ICUs were excluded. The different questions addressed the structure, the practical modalities of therapeutic hypothermia and the use of prognostic factors in patients admitted after cardiac arrest.
One hundred and thirty-two out of 357 ICUs (37%) answered the questionnaire. Adherence to recommendations regarding the targeted temperature and hypothermia duration were 98% and 94% respectively. Both guidelines were followed in 92% ICUs. During therapeutic hypothermia, sedative drugs were given in 99% ICUs, mostly midazolam (77%) and sufentanil (59%). Neuromuscular blocking agents (NMBA) were used in 97% ICUs, mainly cisatracurium (77%). Numerous prognostic factors were used after cardiac arrest such as clinical factors (95%), biomarkers (53%), electroencephalography (78%) and evoked potentials (35%).
In France, adherence to recommendations for therapeutic hypothermia after cardiac arrest is higher than those previously reported in other countries. Numerous prognostic factors are widely used even if their reliability remains controversial.
PMCID: PMC3458038  PMID: 23049783
12.  Neonatal Thrombocytopenia after Perinatal Asphyxia Treated with Hypothermia: A Retrospective Case Control Study 
Our objective was to estimate the effect of therapeutic hypothermia on platelet count in neonates after perinatal asphyxia. We performed a retrospective case control study of all (near-) term neonates with perinatal asphyxia admitted between 2004 and 2012 to our neonatal intensive care unit. All neonates treated with therapeutic hypothermia were included in this study (hypothermia group) and compared with a historic control group of neonates with perinatal asphyxia treated before introduction of therapeutic hypothermia (2008). Primary outcome was thrombocytopenia during the first week after birth. Thrombocytopenia was found significantly more often in the hypothermia group than in the control group, 80% (43/54) versus 59% (27/46) (P = .02). The lowest mean platelet count in the hypothermia group and control group was 97 × 109/L and 125 × 109/L (P = .06), respectively, and was reached at a mean age of 4.1 days in the hypothermia group and 2.9 days in the control group (P < .001). The incidence of moderate/severe cerebral hemorrhage was 6% (3/47) in the hypothermia group versus 9% (3/35) in the control group (P = .64). In conclusion, neonates with perinatal asphyxia treated with therapeutic hypothermia are at increased risk of thrombocytopenia, without increased risk of cerebral hemorrhage.
PMCID: PMC4158299  PMID: 25214854
13.  Therapeutic hypothermia in asphyxiated neonates with hypoxic-ischemic encephalopathy: A single-center experience from its first application in Greece 
Hippokratia  2014;18(3):226-230.
Therapeutic hypothermia has become an established therapy in asphyxiated neonates with evidence of moderate/severe hypoxic-ischemic encephalopathy. Herein, we describe our recent experience with total body cooling in asphyxiated neonates, which is the first relevant report in Greece.
Patients and Methods:
The medical records of all asphyxiated newborns treated with therapeutic hypothermia in our center between September 2010 and October 2013 were retrospectively reviewed. We recorded data related to neonatal-perinatal characteristics, whole body cooling and outcome.
Twelve asphyxiated neonates [median gestational age 38 weeks (36-40)] received whole body cooling (rectal temperature 33.5 ± 0.5 oC for 72 hours) during the study period for moderate (n=3) and severe (n=9) hypoxic-ischemic encephalopathy. Cooling was passive in 4 and active in 8 (66.7%) cases. Therapeutic hypothermia was initiated at the median age of 5 hours (0.5-11) after birth. Seven neonates survived (58.3%) to hospital discharge. On follow-up (7-35 months), neurodevelopment outcome was normal in 1 case, while 3, 1 and 2 subjects had mild, moderate and severe impairment, respectively.
Our initial experience with whole body cooling supports its beneficial effect in asphyxiated neonates. This treatment should be offered in all centers involved in the care of such neonates using either simple means (passive cooling) or automated cooling devices. Hippokratia 2014; 18 (3): 226-230.
PMCID: PMC4309142
neonatal encephalopathy; neonatal care; perinatal asphyxia
14.  The effect of therapeutic hypothermia on drug metabolism and drug response: cellular mechanisms to organ function 
Therapeutic hypothermia is being employed, clinically based, on its neuro-protective benefits. Both critical illness and therapeutic hypothermia significantly affect drug disposition, potentially contributing to drug-therapy and drug-disease interaction. Currently, there is limited written information of the known alterations in drug concentration and response during mild hypothermia treatment and there is a limited understanding of the specific mechanisms that underlie alterations in drug concentrations and the potential clinical importance of these changes.
Areas covered
A systemic review of the effect of therapeutic hypothermia on drug metabolism, disposition, and response is provided. Specifically, the clinical and preclinical evidence of the effects of therapeutic hypothermia on blood flow, specific hepatic metabolism pathways, transporter, renal excretion, pharmacodynamics and rewarming effect are reviewed.
Expert Opinion
Available evidence demonstrates that mild hypothermia decreases the clearance of a variety of drugs with apparently little change in drug protein binding. Recent evidence suggests that the magnitude of the change is elimination route specific. Further research is needed to determine the impact of these alterations on both drug concentration and response in order to optimize the hypothermia therapy in this vulnerable patient population.
PMCID: PMC3116014  PMID: 21473710
critical care; drug metabolism; drug response; pharmacokinetics; therapeutic hypothermia
15.  Outcomes of Safety and Effectiveness in a Multicenter Randomized, Controlled Trial of Whole-Body Hypothermia for Neonatal Hypoxic-Ischemic Encephalopathy 
Pediatrics  2008;122(4):e791.
Whole-body hypothermia reduced the frequency of death or moderate/severe disabilities in neonates with hypoxic-ischemic encephalopathy in a randomized, controlled multicenter trial.
Our goal was to evaluate outcomes of safety and effectiveness of hypothermia in infants up to 18 to 22 months of age.
A priori outcomes were evaluated between hypothermia (n = 102) and control (n = 106) groups.
Encephalopathy attributable to causes other than hypoxia-ischemia at birth was not noted. Inotropic support (hypothermia, 59% of infants; control, 56% of infants) was similar during the 72-hour study intervention period in both groups. Need for blood transfusions (hypothermia, 24%; control, 24%), platelet transfusions (hypothermia, 20%; control, 12%), and volume expanders (hypothermia, 54%; control, 49%) was similar in the 2 groups. Among infants with persistent pulmonary hypertension (hypothermia, 25%; control, 22%), nitric-oxide use (hypothermia, 68%; control, 57%) and placement on extracorporeal membrane oxygenation (hypothermia, 4%; control, 9%) was similar between the 2 groups. Non–central nervous system organ dysfunctions occurred with similar frequency in the hypothermia (74%) and control (73%) groups. Rehospitalization occurred among 27% of the infants in the hypothermia group and 42% of infants in the control group. At 18 months, the hypothermia group had 24 deaths, 19 severe disabilities, and 2 moderate disabilities, whereas the control group had 38 deaths, 25 severe disabilities, and 1 moderate disability. Growth parameters were similar between survivors. No adverse outcomes were noted among infants receiving hypothermia with transient reduction of temperature below a target of 33.5°C at initiation of cooling. There was a trend in reduction of frequency of all outcomes in the hypothermia group compared with the control group in both moderate and severe encephalopathy categories.
Although not powered to test these secondary outcomes, whole-body hypothermia in infants with encephalopathy was safe and was associated with a consistent trend for decreasing frequency of each of the components of disability.
PMCID: PMC2819143  PMID: 18829776
hypoxic-ischemic encephalopathy; whole-body hypothermia; safety; effectiveness
16.  Bench-to-bedside review: Hypothermia in traumatic brain injury 
Critical Care  2010;14(1):204.
Traumatic brain injury remains a major cause of death and severe disability throughout the world. Traumatic brain injury leads to 1,000,000 hospital admissions per annum throughout the European Union. It causes the majority of the 50,000 deaths from road traffic accidents and leaves 10,000 patients severely handicapped: three quarters of these victims are young people. Therapeutic hypothermia has been shown to improve outcome after cardiac arrest, and consequently the European Resuscitation Council and American Heart Association guidelines recommend the use of hypothermia in these patients. Hypothermia is also thought to improve neurological outcome after neonatal birth asphyxia. Cardiac arrest and neonatal asphyxia patient populations present to health care services rapidly and without posing a diagnostic dilemma; therefore, therapeutic systemic hypothermia may be implemented relatively quickly. As a result, hypothermia in these two populations is similar to the laboratory models wherein systemic therapeutic hypothermia is commenced very soon after the injury and has shown so much promise. The need for resuscitation and computerised tomography imaging to confirm the diagnosis in patients with traumatic brain injury is a factor that delays intervention with temperature reduction strategies. Treatments in traumatic brain injury have traditionally focussed on restoring and maintaining adequate brain perfusion, surgically evacuating large haematomas where necessary, and preventing or promptly treating oedema. Brain swelling can be monitored by measuring intracranial pressure (ICP), and in most centres ICP is used to guide treatments and to monitor their success. There is an absence of evidence for the five commonly used treatments for raised ICP and all are potential 'double-edged swords' with significant disadvantages. The use of hypothermia in patients with traumatic brain injury may have beneficial effects in both ICP reduction and possible neuro-protection. This review will focus on the bench-to-bedside evidence that has supported the development of the Eurotherm3235Trial protocol.
PMCID: PMC2875496  PMID: 20236503
17.  The global burden of neonatal hypothermia: systematic review of a major challenge for newborn survival 
BMC Medicine  2013;11:24.
To provide evidence on the global epidemiological situation of neonatal hypothermia and to provide recommendations for future policy and research directions.
Using PubMed as our principal electronic reference library, we searched studies for prevalence and risk factor data on neonatal hypothermia in resource-limited environments globally. Studies specifying study location, setting (hospital or community based), sample size, case definition of body temperature for hypothermia, temperature measurement method, and point estimates for hypothermia prevalence were eligible for inclusion.
Hypothermia is common in infants born at hospitals (prevalence range, 32% to 85%) and homes (prevalence range, 11% to 92%), even in tropical environments. The lack of thermal protection is still an underappreciated major challenge for newborn survival in developing countries. Although hypothermia is rarely a direct cause of death, it contributes to a substantial proportion of neonatal mortality globally, mostly as a comorbidity of severe neonatal infections, preterm birth, and asphyxia. Thresholds for the definition of hypothermia vary, and data on its prevalence in neonates is scarce, particularly on a community level in Africa.
A standardized approach to the collection and analysis of hypothermia data in existing newborn programs and studies is needed to inform policy and program planners on optimal thermal protection interventions. Thermoprotective behavior changes such as skin-to-skin care or the use of appropriate devices have not yet been scaled up globally. The introduction of simple hypothermia prevention messages and interventions into evidence-based, cost-effective packages for maternal and newborn care has promising potential to decrease the heavy global burden of newborn deaths attributable to severe infections, prematurity, and asphyxia. Because preventing and treating newborn hypothermia in health institutions and communities is relatively easy, addressing this widespread challenge might play a substantial role in reaching Millennium Development Goal 4, a reduction of child mortality.
PMCID: PMC3606398  PMID: 23369256
hypothermia; mortality; neonatal; newborn; prematurity
18.  Gentamicin Pharmacokinetics and Dosing in Neonates with Hypoxic Ischemic Encephalopathy Receiving Hypothermia 
Pharmacotherapy  2013;33(7):718-726.
Study Objective
To evaluate the pharmacokinetics of gentamicin in neonates with hypoxic ischemic encephalopathy (HIE) receiving hypothermia and to identify an empiric gentamicin dosing strategy in this population that optimizes achievement of target peak and trough concentrations.
Population pharmacokinetic study using retrospective medical record data.
Tertiary neonatal intensive care unit.
A total of 29 term neonates diagnosed with HIE treated with hypothermia who received gentamicin and underwent therapeutic drug monitoring.
Measurement and Main Results
Patient demographics and gentamicin concentration data were retrospectively collected over a 2-year period. A population-based pharmacokinetic model was developed using nonlinear mixed-effects modeling (NONMEM). Using the developed model, Monte Carlo simulations were performed to evaluate the probability of achieving target peak (>6 mg/L) and trough (<2 mg/L) gentamicin concentrations for various potential dosing regimens. A one-compartment model best described the available gentamicin concentration data. Birthweight (BW) and serum creatinine (SCr) significantly influenced gentamicin clearance. For the typical study neonate (BW 3.3 kg; SCr 0.9 mg/dL), clearance was 0.034 L/H/kg and volume was 0.52 L/kg. At a 24-hour dosing interval, Monte Carlo simulations predicted target gentamicin peak and trough concentrations could not be reliably achieved at any dose. At a 36-hour dosing interval, a dose of 4-5 mg/kg is predicted to achieve target gentamicin peak and trough concentrations in >90% of neonates.
Gentamicin clearance is decreased in neonates with HIE treated with hypothermia compared with previous reports in nonasphyxiated normothermic term neonates. A prolonged 36-hour dosing interval will be needed to achieve target gentamicin trough concentrations in this population. Further prospective evaluation of this dosing recommendation is needed.
PMCID: PMC3700641  PMID: 23553582
gentamicin; neonates; pharmacokinetics; hypothermia; hypoxic ischemic encephalopathy
19.  Every 36-hour Gentamicin Dosing in Neonates with Hypoxic Ischemic Encephalopathy Receiving Hypothermia 
To examine the impact of a change in the empiric gentamicin dose from 5 mg/kg every 24h to 5 mg/kg every 36h on target drug concentration achievement in neonates with hypoxic ischemic encephalopathy (HIE) receiving therapeutic hypothermia.
Study Design
Gentamicin drug concentrations in neonates with HIE receiving therapeutic hypothermia were examined during two time periods in a retrospective chart review. During the initial treatment period (November 2007 to March 2010; n=29), neonates received gentamicin 5 mg/kg every 24h (Q24h period). During the second treatment period (January 2011 to May 2012; n=23), the dose was changed to 5 mg/kg every 36h (Q36h period). Cooling criteria and protocol remained the same between treatment periods. Gentamicin drug concentrations including achievement of target trough concentrations (<2 mg/L) were compared between treatment periods. Individual Bayesian estimates of gentamicin clearance were also compared.
Neonates with an elevated trough concentration >2 mg/L decreased from 38% to 4% with implementation of a Q36h dosing interval (P<0.007). The mean gentamicin trough concentration was 2.0 ± 0.8 mg/L during the Q24h period and 0.9 ± 0.4 mg/L during the Q36h period (P<0.001). Peak concentrations were minimally impacted (Q24h 11.4 ± 2.3 mg/L vs. Q36h 10.0 ± 1.9 mg/L; P=0.05). The change in gentamicin trough concentration could not be accounted for by differences in gentamicin clearance between treatment periods (P=0.9).
A 5 mg/kg every 36h gentamicin dosing strategy in neonates with HIE receiving therapeutic hypothermia improved achievement of target trough concentration <2 mg/L while still providing high peak concentration exposure.
PMCID: PMC3762884  PMID: 23702622
gentamicin; neonates; pharmacokinetics; hypothermia; hypoxic ischemic encephalopathy
20.  Mild Hypothermia Decreases Fentanyl and Midazolam Steady-State clearance in a Rat Model of Cardiac Arrest 
Critical Care Medicine  2012;40(4):1221-1228.
Therapeutic hypothermia is widely-employed for neuroprotection after cardiac arrest(CA). However, concern regarding elevated drug concentrations during hypothermia and increased adverse drug reaction risk complicates concurrent pharmacotherapy. Many commonly used medications in critically ill patients rely on the cytochrome P450(CYP) 3A isoform for their elimination. Therefore, our study objectives were to determine the effect of mild hypothermia on the in vivo pharmacokinetics of fentanyl and midazolam, two clinically-relevant CYP3A substrates, after CA and to investigate the mechanisms of these alterations.
Prospective, randomized, controlled study
University research laboratory
Thirty two adult male Sprague-Dawley rats
An asphyxial CA rat model was used and mild hypothermia(33 °C) was induced 1h post injury by surface cooling and continued for 10 hours to mimic the prolonged clinical application of hypothermia accompanied by intensive care interventions. Fentanyl and midazolam were independently administered by intravenous infusion and plasma and brain concentrations were analyzed using ultra-performance liquid chromatography tandem mass spectrometry. Cyp3a2 protein expression was measured and a Michaelis-Menten enzyme kinetic analysis was performed at 37°C and 33°C using control rat microsomes.
Measurements and Main Results
Mild hypothermia decreased the systemic clearance of both fentanyl (61.5±11.5 to 48.9±8.95 mL/min/kg;p < 0.05) and midazolam (89.2±12.5 to 73.6±12.1 mL/min/kg;p < 0.05) after CA. The elevated systemic concentrations did not lead to parallel increased brain exposures of either drug. Mechanistically, no differences in Cyp3a2 expression was observed, but the in vitro metabolism of both drugs was decreased at 33 °C versus 37 °C through reductions in enzyme metabolic capacity rather than substrate affinity.
Mild hypothermia reduces the systemic clearances of fentanyl and midazolam in rats after CA through alterations in Cyp3a metabolic capacity rather than enzyme affinity as observed with other CYPs. Contrasting effects on blood and brain levels further complicates drug dosing. Consideration of the impact of hypothermia on medications whose clearance is dependent on CYP3A metabolism is warranted.
PMCID: PMC3307845  PMID: 22067624
hypothermia; cardiac arrest; drug metabolism; pharmacokinetics; midazolam; fentanyl
21.  Perinatal asphyxia: current status and approaches towards neuroprotective strategies, with focus on sentinel proteins 
Neurotoxicity Research  2010;19(4):603-627.
Delivery is a stressful and risky event menacing the newborn. The mother-dependent respiration has to be replaced by autonomous pulmonary breathing immediately after delivery. If delayed, it may lead to deficient oxygen supply compromising survival and development of the central nervous system. Lack of oxygen availability gives rise to depletion of NAD+ tissue stores, decrease of ATP formation, weakening of the electron transport pump and anaerobic metabolism and acidosis, leading necessarily to death if oxygenation is not promptly re-established. Re-oxygenation triggers a cascade of compensatory biochemical events to restore function, which may be accompanied by improper homeostasis and oxidative stress. Consequences may be incomplete recovery, or excess reactions that worsen the biological outcome by disturbed metabolism and/or imbalance produced by over-expression of alternative metabolic pathways. Perinatal asphyxia has been associated with severe neurological and psychiatric sequelae with delayed clinical onset. No specific treatments have yet been established. In the clinical setting, after resuscitation of an infant with birth asphyxia, the emphasis is on supportive therapy. Several interventions have been proposed to attenuate secondary neuronal injuries elicited by asphyxia, including hypothermia. Although promising, the clinical efficacy of hypothermia has not been fully demonstrated. It is evident that new approaches are warranted. The purpose of this review is to discuss the concept of sentinel proteins as targets for neuroprotection. Several sentinel proteins have been described to protect the integrity of the genome (e.g. PARP-1; XRCC1; DNA ligase IIIα; DNA polymerase β, ERCC2, DNA-dependent protein kinases). They act by eliciting metabolic cascades leading to (i) activation of cell survival and neurotrophic pathways; (ii) early and delayed programmed cell death, and (iii) promotion of cell proliferation, differentiation, neuritogenesis and synaptogenesis. It is proposed that sentinel proteins can be used as markers for characterising long-term effects of perinatal asphyxia, and as targets for novel therapeutic development and innovative strategies for neonatal care.
PMCID: PMC3291837  PMID: 20645042
Hypoxia; Poly(ADP-ribose) polymerase; Neonatal; Apoptosis; Neurogenesis; Developmental deficits; Rats
22.  Early Antioxidant Treatment and Delayed Hypothermia After Hypoxia-Ischemia Have No Additive Neuroprotection in Newborn Pigs 
Anesthesia and analgesia  2012;115(3):627-637.
The implementation and clinical efficacy of hypothermia in neonatal hypoxic-ischemic (HI) encephalopathy are limited, in part, by the delay in instituting hypothermia and access to equipment. In a piglet model of HI, half of the neurons in putamen already showed ischemic cytopathology by 6 hours of recovery. We tested the hypothesis that treatment with the superoxide dismutase-catalase mimetic EUK-134 at 30 minutes of recovery provides additive neuronal protection when combined with one day of whole body hypothermia implemented 4 hours after resuscitation.
Anesthetized piglets were subjected to 40 minutes of hypoxia (10% inspired oxygen) followed by 7 minutes of airway occlusion and resuscitation. Body temperature was maintained at 38.5°C in normothermic groups and at 34°C in hypothermic groups. All groups were mechanically ventilated, sedated, and received muscle relaxants during the first day of recovery. Neuropathology was assessed by profile and stereological cell counting methods.
At 10 days of recovery, neuronal viability in putamen of a normothermic group treated with saline vehicle was reduced to 17±6% (±95% confidence interval) of the value in a sham-operated control group (100±15%). Intravenous infusion of EUK-134 (2.5 mg/kg at 30 minutes of recovery + 1.25 mg/kg/h until 4 hours of recovery) with normothermic recovery resulted in 40±12% viable neurons in putamen. Treatment with saline vehicle followed by delayed hypothermia resulted in partial protection (46±15%). Combining early EUK-134 treatment with delayed hypothermia also produced partial protection (47±18%) that was not significantly greater than single treatment with EUK-134 (confidence interval of difference: −15% to 29%) or delayed hypothermia (−16% to 19%). Furthermore, no additive neuroprotection was detected in caudate nucleus or parasagittal neocortex, where neuronal loss was less severe.
We conclude that early treatment with this antioxidant does not substantially enhance the therapeutic benefit of delayed hypothermia in protecting highly vulnerable neurons in HI-insulted newborns, possibly because basal ganglia neurons are already undergoing irreversible cell death signaling by the time EUK-134 is administered or because this compound and hypothermia attenuate similar mechanisms of injury.
PMCID: PMC3425722  PMID: 22745113
23.  Overview of Therapeutic Hypothermia 
Therapeutic Hypothermia has proven neuroprotective effects in global cerebral ischemia. Indications for hypothermia induction include cardiac arrest and neonatal asphyxia. The two general methods of induced hypothermia are either surface cooling or endovascular cooling. Hypothermia should be induced as early as possible to achieve maximum neuroprotection and edema blocking effect. Endovascular cooling has the benefit of shorter time to reach target temperature but catheter insertion requires expertise and training, which may be a barrier to widespread availability. The optimum method of cooling is yet to be determined but a multimodal approach is necessary to address three phases of cooling: induction, maintentance, and re-warm. Specifying core practitioners who are well-versed in established guidelines can help integrate the multidisciplinary team that is needed to successfully implement cooling protocols. Reducing shivering to make heat exchange more efficient with tighter temperature control enables quicker time to target temperature and avoids re-warming which can lead to inadvertent increase in intracranial pressure and cerebral edema. Promising applications but yet to be determined is whether hypothermia treatment can improve outcomes in acute ischemic stroke or traumatic brain injury.
PMCID: PMC3519955  PMID: 23007950
Hypothermia; Therapeutic hypothermia; Cardiac arrest; Cerebral ischemia; Surface cooling; Endovascular cooling; Shivering; Neuroprotection; Treatment
24.  Cost-effective therapeutic hypothermia treatment device for hypoxic ischemic encephalopathy 
Despite recent advances in neonatal care and monitoring, asphyxia globally accounts for 23% of the 4 million annual deaths of newborns, and leads to hypoxic-ischemic encephalopathy (HIE). Occurring in five of 1000 live-born infants globally and even more in developing countries, HIE is a serious problem that causes death in 25%–50% of affected neonates and neurological disability to at least 25% of survivors. In order to prevent the damage caused by HIE, our invention provides an effective whole-body cooling of the neonates by utilizing evaporation and an endothermic reaction. Our device is composed of basic electronics, clay pots, sand, and urea-based instant cold pack powder. A larger clay pot, lined with nearly 5 cm of sand, contains a smaller pot, where the neonate will be placed for therapeutic treatment. When the sand is mixed with instant cold pack urea powder and wetted with water, the device can extract heat from inside to outside and maintain the inner pot at 17°C for more than 24 hours with monitoring by LED lights and thermistors. Using a piglet model, we confirmed that our device fits the specific parameters of therapeutic hypothermia, lowering the body temperature to 33.5°C with a 1°C margin of error. After the therapeutic hypothermia treatment, warming is regulated by adjusting the amount of water added and the location of baby inside the device. Our invention uniquely limits the amount of electricity required to power and operate the device compared with current expensive and high-tech devices available in the United States. Our device costs a maximum of 40 dollars and is simple enough to be used in neonatal intensive care units in developing countries.
PMCID: PMC3540914  PMID: 23319871
therapeutic hypothermia; evaporative cooling; hypoxic ischemic encephalopathy; birth asphyxia; neuroprotection
25.  Systematic Review and Meta-Analysis of Therapeutic Hypothermia in Animal Models of Spinal Cord Injury 
PLoS ONE  2013;8(8):e71317.
Therapeutic hypothermia is a clinically useful neuroprotective therapy for cardiac arrest and neonatal hypoxic ischemic encephalopathy and may potentially be useful for the treatment of other neurological conditions including traumatic spinal cord injury (SCI). The pre-clinical studies evaluating the effectiveness of hypothermia in acute SCI broadly utilise either systemic hypothermia or cooling regional to the site of injury. The literature has not been uniformly positive with conflicting studies of varying quality, some performed decades previously.
In this study, we systematically review and meta-analyse the literature to determine the efficacy of systemic and regional hypothermia in traumatic SCI, the experimental conditions influencing this efficacy, and the influence of study quality on outcome. Three databases were utilised; PubMed, ISI Web of Science and Embase. Our inclusion criteria consisted of the (i) reporting of efficacy of hypothermia on functional outcome (ii) number of animals and (iii) mean outcome and variance in each group.
Systemic hypothermia improved behavioural outcomes by 24.5% (95% CI 10.2 to 38.8) and a similar magnitude of improvement was seen across a number of high quality studies. The overall behavioural improvement with regional hypothermia was 26.2%, but the variance was wide (95% CI −3.77 to 56.2). This result may reflect a preponderance of positive low quality data, although a preferential effect of hypothermia in ischaemic models of injury may explain some of the disparate data. Sufficient heterogeneity was present between studies of regional hypothermia to reveal a number of factors potentially influencing efficacy, including depth and duration of hypothermia, animal species, and neurobehavioural assessment. However, these factors could reflect the influence of earlier lower quality literature.
Systemic hypothermia appears to be a promising potential method of treating acute SCI on the basis of meta-analysis of the pre-clinical literature and the results of high quality animal studies.
PMCID: PMC3739756  PMID: 23951131

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