Supratherapeutic Vancomycin Concentrations Associated With Hypothermia in a Burn Patient

Hypothermia is a dangerous adverse effect that occurs in burn patients. Hypothermia leads to decreased renal blood flow and may decrease renal clearance of medications. Few human studies examine the effect of hypothermia on drug clearance and no known studies examine its effect on vancomycin clearance in burn patients. This case report describes a 39-year-old female who suffered 60% total body surface area third-degree burns. The patient required vancomycin, empirically, and for definitive treatment of methicillin-resistant Staphylococcus aureus. During three of the vancomycin courses, the patient experienced significant hypothermia. Vancomycin concentrations obtained during normothermia were found to be subtherapeutic or therapeutic. Concentrations obtained during hypothermia were found to be supratherapeutic and rate elimination constants were found to be significantly decreased by 45, 25, and 31%, respectively. These patient data suggest that hypothermia can decrease vancomycin clearance in burn patients as evidenced by supratherapeutic vancomycin concentrations and decreased rate elimination constants. Burn patients should be monitored closely for hypothermia. If hypothermia occurs during treatment, vancomycin concentrations should be obtained frequently, even if renal function appears stable. Dosing based on concentrations may be necessary in order to avoid supratherapeutic vancomycin concentrations and associated adverse drug events.

Effect of hypothermia on interleukin-1 receptor antagonist pharmacodynamics in inflammatory-sensitized hypoxic-ischemic encephalopathy of term newborns

Background

Hypothermia is increasingly tested in several neurological conditions, such as neonatal encephalopathy, stroke, traumatic brain injury, subarachnoid hemorrhage, spinal cord injury, and neurological outcomes of cardiac arrest. Current studies aim to increase benefits of hypothermia with new add-on therapies including immunomodulatory agents. Hypothermia has been shown to affect the metabolism of commonly used drugs, including those acting on neuroimmune pathways.

Objective

This study focuses on the effect of hypothermia on interleukin-1 receptor antagonist pharmacodynamics in a model of neonatal encephalopathy.

Methods

The effect of hypothermia on (i) the tissue concentration of the interleukin-1 receptor antagonist, (ii) the interleukin-1 inflammatory cascade, and (iii) the neuroprotective potential of interleukin-1 receptor antagonist has been assessed on our rat model of neonatal encephalopathy resulting from inflammation induced by bacterial compound plus hypoxia-ischemia.

Results

Hypothermia reduced the surface of core and penumbra lesions, as well as alleviated the brain weight loss induced by LPS+HI exposure. Hypothermia compared to normothermia significantly increased (range 50–65%) the concentration of the interleukin-1 receptor antagonist within the central nervous system. Despite this increase of intracerebral interleukin-1 receptor antagonist concentration, the intracerebral interleukin-1-induced tumor necrosis factor-alpha cascade was upregulated. In hypothermic condition, the known neuroprotective effect of interleukin-1 receptor antagonist was neutralized (50 mg/kg/12 h for 72 h) or even reversed (200 mg/kg/12 h for 72 h) as compared to normothermic condition.

Conclusion

Hypothermia interferes with the pharmacodynamic parameters of the interleukin-1 receptor antagonist, through a bioaccumulation of the drug within the central nervous system and a paradoxical upregulation of the interleukin-1 pathway. These effects seem to be at the origin of the loss of efficiency or even toxicity of the interleukin-1 receptor antagonist when combined with hypothermia. Such bioaccumulation could happen similarly with the use of other drugs combined to hypothermia in a clinical context.

Effect of hypothermia treatment on gentamicin pharmacokinetics in neonates with hypoxic-ischaemic encephalopathy: A systematic review and meta-analysis

WHAT IS KNOWN AND OBJECTIVE

Hypothermia is the current standard therapy for asphyxiated neonates with hypoxic-ischaemic encephalopathy (HIE). Gentamicin is used for the empirical treatment of early-onset neonatal sepsis. We investigated the influence of hypothermia treatment on gentamicin pharmacokinetics and suggested the appropriate dosing recommendations for gentamicin in neonates with HIE receiving hypothermia treatment.

METHODS

We searched studies published until February 2017 in MEDLINE using PubMed, EMBASE and the Cochrane Library. Three independent reviewers screened the literature and extracted data from each study. All of the studies that reported the blood concentrations or pharmacokinetic parameters of gentamicin in hypothermic neonates with HIE were included in this review. Articles were excluded if they were not original research.

RESULT AND DISCUSSION

A total of 8 observational studies met the inclusion criteria. Meta-analyses were performed in which the mean difference of gentamicin for the trough concentration and clearance between hypothermic and normothermic neonates were 0.81 mg/L (95% confidence interval [-0.07, 1.69]) and -0.21 mL/kg/min (95% confidence interval [-0.31, -0.12]), respectively. The factors affecting gentamicin clearance in hypothermic neonates with HIE were gestational age, birthweight and serum creatinine.

WHAT IS NEW AND CONCLUSION

Gentamicin clearance is decreased in neonates with HIE receiving hypothermia treatment compared to those not receiving hypothermia treatment. Modified gentamicin dosing regimens are required to avoid potential toxicity related to higher concentrations during hypothermia treatment.

Pharmacokinetic considerations for pediatric patients receiving analgesia in the intensive care unit; targeting postoperative, ECMO and hypothermia patients

INTRODUCTION

Adequate postoperative analgesia in pediatric patients in the intensive care unit (ICU) matters, since untreated pain is associated with negative outcomes. Compared to routine postoperative patients, children undergoing hypothermia (HT) or extracorporeal membrane oxygenation (ECMO), or recovering after cardiac surgery likely display non-maturational differences in pharmacokinetics (PK) and pharmacodynamics (PD). These differences warrant additional dosing recommendations to optimize pain treatment. Areas covered: Specific populations within the ICU will be discussed with respect to expected variations in PK and PD for various analgesics. We hereby move beyond maturational changes and focus on why PK/PD may be different in children undergoing HT, ECMO or cardiac surgery. We provide a stepwise manner to develop PK-based dosing regimens using population PK approaches in these populations. Expert opinion: A one-dose to size-fits-all for analgesia is suboptimal, but for several commonly used analgesics the impact of HT, ECMO or cardiac surgery on average PK parameters in children is not yet sufficiently known. Parameters considering both maturational and non-maturational covariates are important to develop population PK-based dosing advices as part of a strategy to optimize pain treatment.

Severity of asphyxia is a covariate of phenobarbital clearance in newborns undergoing hypothermia

AIM

Phenobarbital (PB) pharmacokinetics (PK) in asphyxiated newborns show large variability, not only explained by hypothermia (HT). We evaluated potential relevant covariates of PK of PB in newborns treated with or without HT for hypoxic-ischemic encephalopathy (HIE).

METHODS

Clearance (CL), distribution volume (Vd) and elimination half-life (t_1/2) were calculated using one-compartment analysis. Covariates were clinical characteristics (weight, gestational age, hepatic, renal, and circulatory status), comedication and HIE severity [time to reach normal aEEG pattern (T_normaEEG), dichotomous, within 24 h] and asphyxia severity [severe aspyhxia = pH ≤7.1 + Apgar score ≤5 (5 min), dichotomous]. Student's t-test, two-way ANOVA, correlation and Pearson's chi-square test were used.

RESULTS

Forty newborns were included [14 non-HT; 26 HT with T_normaEEG <24 h in 14/26 (group_1-HT) and T_normaEEG ≥24 h in 12/26 (group_2-HT)]. Severe asphyxia was present in 26/40 [5/14 non-HT, 11/14 and 10/12 in both HT groups]. PB-CL, Vd and t_1/2 were similar between the non-HT and HT group. However, within the HT group, PB-CL was significantly different between group_1-HT and group_2-HT (p = .043). ANOVA showed that HT (p = .034) and severity of asphyxia (p = .038) reduced PB-CL (-50%).

CONCLUSION

The interaction of severity of asphyxia and HT is associated with a clinical relevant reduced PB-CL, suggesting the potential relevance of disease characteristics beyond HT itself.

Correction to: Pharmacokinetics of Fentanyl and Its Derivatives in Children: A Comprehensive Review

Fentanyl and its derivatives sufentanil, alfentanil, and remifentanil are potent opioids. A comprehensive review of the use of fentanyl and its derivatives in the pediatric population was performed using the National Library of Medicine PubMed. Studies were included if they contained original pharmacokinetic parameters or models using established routes of administration in patients younger than 18 years of age. Of 372 retrieved articles, 44 eligible pharmacokinetic studies contained data of 821 patients younger than 18 years of age, including more than 46 preterm infants, 64 full-term neonates, 115 infants/toddlers, 188 children, and 28 adolescents. Underlying diagnoses included congenital heart and pulmonary disease and abdominal disorders. Routes of drug administration were intravenous, epidural, oral-transmucosal, intranasal, and transdermal. Despite extensive use in daily clinical practice, few studies have been performed. Preterm and term infants have lower clearance and protein binding. Pharmacokinetics was not altered by chronic renal or hepatic disease. Analyses of the pooled individual patients' data revealed that clearance maturation relating to body weight could be best described by the Hill function for sufentanil (R ² = 0.71, B _max 876 mL/min, K ₅₀ 16.3 kg) and alfentanil (R ² = 0.70, B _{max (fixed)} 420 mL/min, K ₅₀ 28 kg). The allometric exponent for estimation of clearance of sufentanil was 0.99 and 0.75 for alfentanil clearance. Maturation of remifentanil clearance was described by linear regression to bodyweight (R ² = 0.69). The allometric exponent for estimation of remifentanil clearance was 0.76. For fentanyl, linear regression showed only a weak correlation between clearance and bodyweight in preterm and term neonates (R ² = 0.22) owing to a lack of data in older age groups. A large heterogeneity regarding study design, clinical setting, drug administration, laboratory assays, and pharmacokinetic estimation was observed between studies introducing bias into the analyses performed in this review. A limitation of this review is that pharmacokinetic data, based on different modes of administration, dosing schemes, and parameter estimation methods, were combined.

Amikacin Pharmacokinetics To Optimize Dosing in Neonates with Perinatal Asphyxia Treated with Hypothermia

Aminoglycoside pharmacokinetics (PK) is expected to change in neonates with perinatal asphyxia treated with therapeutic hypothermia (PATH). Several amikacin dosing guidelines have been proposed for treating neonates with (suspected) septicemia; however, none provide adjustments for cases of PATH. Therefore, we aimed to quantify the differences in amikacin PK between neonates with and without PATH to propose suitable dosing recommendations. Based on amikacin therapeutic drug monitoring data collected retrospectively from neonates with PATH, combined with a published data set, we assessed the impact of PATH on amikacin PK by using population modeling. Monte Carlo and stochastic simulations were performed to establish amikacin exposures in neonates with PATH after dosing according to the current guidelines and according to proposed model-derived dosing guidelines. Amikacin clearance was decreased 40.6% in neonates with PATH, with no changes in volume of distribution. Simulations showed that increasing the dosing interval by 12 h results in a decrease in the percentage of neonates reaching toxic trough levels (>5 mg/liter), from 40 to 76% to 14 to 25%, while still reaching efficacy targets compared to the results of current dosing regimens. Based on this study, a 12-h increase in the amikacin dosing interval in neonates with PATH is proposed to correct for the reduced clearance, yielding safe and effective exposures. As amikacin is renally excreted, further studies into other renally excreted drugs may be required, as their clearance may also be impaired.

Population Pharmacokinetics of Amoxicillin in Term Neonates Undergoing Moderate Hypothermia

The pharmacokinetics (PK) of amoxicillin in asphyxiated newborns undergoing moderate hypothermia were quantified using prospective data (N = 125). The population PK was described by a 2-compartment model with a priori birthweight (BW) based allometric scaling. Significant correlations were observed between clearance (Cl) and postnatal age (PNA), gestational age (GA), body temperature (TEMP), and urine output (UO). For a typical patient with GA 40 weeks, BW 3,000 g, 2 days PNA (i.e., TEMP 33.5°C), and normal UO, Cl was 0.26 L/h (interindividual variability (IIV) 41.9%) and volume of distribution of the central compartment was 0.34 L/kg (IIV of 114.6%). For this patient, Cl increased to 0.41 L/h at PNA 5 days and TEMP 37.0°C. The respective contributions of both covariates were 23% and 27%. Based on Monte Carlo simulations we recommend 50 and 75 mg/kg/24h amoxicillin in three doses for patients with GA 36-37 and 38-42 weeks, respectively.

Uptake of dendrimer-drug by different cell types in the hippocampus after hypoxic-ischemic insult in neonatal mice: Effects of injury, microglial activation and hypothermia

Perinatal hypoxic-ischemic encephalopathy (HIE) can result in neurodevelopmental disability, including cerebral palsy. The only treatment, hypothermia, provides incomplete neuroprotection. Hydroxyl polyamidoamine (PAMAM) dendrimers are being explored for targeted delivery of therapy for HIE. Understanding the biodistribution of dendrimer-conjugated drugs into microglia, neurons and astrocytes after brain injury is essential for optimizing drug delivery. We conjugated N-acetyl-L-cysteine to Cy5-labeled PAMAM dendrimer (Cy5-D-NAC) and used a mouse model of perinatal HIE to study effects of timing of administration, hypothermia, brain injury, and microglial activation on uptake. Dendrimer conjugation delivered therapy most effectively to activated microglia but also targeted some astrocytes and injured neurons. Cy5-D-NAC uptake was correlated with brain injury in all cell types and with activated morphology in microglia. Uptake was not inhibited by hypothermia, except in CD68+ microglia. Thus, dendrimer-conjugated drug delivery can target microglia, astrocytes and neurons and can be used in combination with hypothermia for treatment of HIE.

The beneficial hemodynamic effects of afterload reduction by sodium nitroprusside during rewarming from experimental hypothermia

BACKGROUND

Rewarming from hypothermia is associated with depressed cardiac function, known as hypothermia-induced cardiac dysfunction (HCD), and increased systemic vascular resistance (SVR). Previous studies on pharmacological treatment of HCD have demonstrated beneficial effects when using drugs with the combined effects; cardiac inotropic support and peripheral vasodilation. The presented study aims to investigate the isolated effects of arterial dilatation on cardiac functional variables during rewarming from hypothermia using sodium nitroprusside (SNP).

METHODS

We utilized a rat model designed to induce HCD following 4 h at 15 °C and rewarming. To study effects on left ventricular (LV) functional variables in response to afterload reduction by SNP during rewarming a conductance catheter was used. Index of LV contractility, preload recruitable stroke work (PRSW), was obtained with inferior vena cava occlusions at 37 °C before and after hypothermia. Pressure signals from a catheter in the left femoral artery was used to pharmacologically adjust SVR.

RESULTS

After rewarming both animal groups showed significant reduction in both SV and CO as a manifestation of HCD. However, compared to saline controls, SV and CO in SNP-treated animals increased significantly during rewarming in response to afterload reduction displayed as reduced SVR, mean arterial- and end-systolic pressures. The cardiac contractility variable PRSW was equally reduced after rewarming in both groups.

CONCLUSION

When rewarming the present model of HCD a significant increase in SVR takes place. In this context, pharmacologic intervention aimed at reducing SVR show clear positive results on CO and SV. However, a reduction in SVR alone is not sufficient to fully alleviate CO during HCD, and indicate the need of additional inotropic support.

The influence of targeted temperature management on the pharmacokinetics of drugs administered during and after cardiac arrest: a systematic review

OBJECTIVE

Pharmacokinetic parameters of drugs are widely investigated under normothermic conditions and normal hemodynamic parameters. The European Resuscitation Council recommends the use of targeted temperature management (TTM) with a target temperature of 34 °C in cardiac arrest (CA) patients. The aim of this literature review is to investigate the influence of CA combined with TTM on the pharmacokinetics of drugs. Results of preclinical and clinical studies are compared with each other. Only the most important drugs, administered during CA in emergency setting, were studied.

METHODS

A literature search was conducted within PubMed and Google Scholar. The search terms included 'therapeutic hypothermia', 'TTM', 'drug metabolism', 'pharmacokinetics during hypothermia', 'cardiac arrest/etiology'. In Pubmed, MeSH-terms were also included: 'myocardial infarction/therapy', 'heart arrest/complications' and 'hypothermia'. To search for preclinical studies: the search terms 'pigs' and 'swine' were used. After the primary shift of relevant findings, further articles were found through references of these (snowballing method), as well as through related articles as suggested by the databases.

RESULTS

Due to the reduced cardiac output during TTM, most of the distribution volume ([Formula: see text]) of drugs included in this literature study is decreased. Only the [Formula: see text] of chlorzoxazone in CA rats and midazolam in non-CA patients are significantly increased during respectively deep and mild hypothermia. The renal, hepatic and biliary clearance of drugs administered during CA/TTM/hypothermia are decreased.

DISCUSSION

The combination of a decreased [Formula: see text] and a decrease in the metabolization/excretion of drugs during CA/TTM result in higher plasma concentrations compared to the plasma concentrations during CA without TTM.

Dosing antibiotic prophylaxis during cardiopulmonary bypass-a higher level of complexity? A structured review

In highly invasive procedures such as open heart surgery, the risk of post-operative infection is particularly high due to exposure of the surgical field to multiple foreign devices. Adequate antibiotic prophylaxis is an essential intervention to minimise post-operative morbidity and mortality. However, there is a lack of clear understanding on the adequacy of traditional prophylactic dosing regimens, which are rarely supported by data. The aim of this structured review is to describe the relevant pharmacokinetic/pharmacodynamic (PK/PD) considerations for optimal antibiotic prophylaxis for major cardiac surgery including cardiopulmonary bypass (CPB). A structured review of the relevant published literature was performed and 45 relevant studies describing antibiotic pharmacokinetics in patients receiving extracorporeal CPB as part of major cardiac surgery were identified. Some of the studies suggested marked PK alterations in the peri-operative period with increases in volume of distribution (V_d) by up to 58% and altered drug clearances of up to 20%. Mechanisms proposed as causing the PK changes included haemodilution, hypothermia, retention of the antibiotic within the extracorporeal circuit, altered physiology related to a systemic inflammatory response, and maldistribution of blood flow. Of note, some studies reported no or minimal impact of the CPB procedure on antibiotic pharmacokinetics. Given the inconsistent data, ongoing research should focus on clarifying the influence of CPB procedure and related clinical covariates on the pharmacokinetics of different antibiotics during cardiac surgery. Traditional prophylactic dosing regimens may need to be re-assessed to ensure sufficient drug exposures that will minimise the risk of surgical site infections.

Adverse drug reactions in therapeutic hypothermia after cardiac arrest

BACKGROUND

Therapeutic hypothermia (TH) improves survival and neurologic function in comatose survivors of cardiac arrest. Many medications used to support TH have altered pharmacokinetics and pharmacodynamics during this treatment. It is unknown if or at what frequency the medications used during TH cause adverse drug reactions (ADRs).

METHODS

A retrospective chart review was conducted for patients admitted to an intensive care unit (ICU) after cardiac arrest and treated with TH from January 2009 to June 2012 at two urban, university-affiliated, tertiary-care medical centres. Medications commonly used during TH were screened for association with significant ADRs (grade 3 or greater per Common Terminology Criteria for Adverse Events) using three published ADR detection instruments.

RESULTS

A total of 229 patients were included, the majority being males with median age of 62 presenting with an out-of-hospital cardiac arrest in pulseless electrical activity or asystole. The most common comorbidities were hypertension, coronary artery disease, and diabetes mellitus. There were 670 possible ADRs and 69 probable ADRs identified. Of the 670 possible ADRs, propofol, fentanyl, and acetaminophen were the most common drugs associated with ADRs. Whereas fentanyl, insulin, and propofol were the most common drugs associated with a probable ADR. Patients were managed with TH for a median of 22 hours, with 38% of patients surviving to hospital discharge.

CONCLUSIONS

Patients undergoing TH after cardiac arrest frequently experience possible adverse reactions associated with medications and the corresponding laboratory abnormalities are significant. There is a need for judicious use and close monitoring of drugs in the setting of TH until recommendations for dose adjustments are available to help prevent ADRs.

Neuromuscular Blockade in the 21st Century Management of the Critically Ill Patient

Neuromuscular blockings agents (NMBAs) have a controversial role in the ventilatory and medical management of critical illness. The clinical concern surrounding NMBA-induced complications stems from evidence presented in the 2002 clinical practice guidelines, but new evidence from subsequent randomized trials and studies provides a more optimistic outlook about the application of NMBAs in the ICU. Furthermore, changes in the delivery of critical care, such as protocolized care pathways, minimizing or interrupting sedation, increased monitoring techniques, and overall improvements in reducing immobility, have created a modern, 21st century ICU environment whereby NMBAs may be administered safely. In this article we start with a review of the mechanism of action, side effects, and pharmacology of commonly used NMBAs. We then address the rationale for NMBA use for an expanding number of indications (endotracheal intubation, acute respiratory distress syndrome, status asthmaticus, increased intracranial and intra-abdominal pressure, and therapeutic hypothermia after cardiac arrest), with an emphasis on NMBA use in facilitating lung-protective ventilation for respiratory failure. We end with an appraisal over the importance of monitoring depth of paralysis and the concerns of complications, such as prolonged skeletal muscle weakness. In the context of adequate sedation and analgesia, monitored NMBA use (continuous or bolus administration) can be considered for the small number of clinical indications in critically ill patients for which evidence currently exists.

The Evolving Paradigm of Individualized Postresuscitation Care After Cardiac Arrest

The postresuscitation period after a cardiac arrest is characterized by a wide range of physiological derangements. Variations between patients include preexisting medical problems, the underlying cause of the cardiac arrest, presence or absence of hemodynamic and circulatory instability, severity of the ischemia-reperfusion injury, and resuscitation-related injuries such as pulmonary aspiration and rib or sternal fractures. Although protocols can be applied to many elements of postresuscitation care, the widely disparate clinical condition of cardiac arrest survivors requires an individualized approach that stratifies patients according to their clinical profile and targets specific treatments to patients most likely to benefit. This article describes such an individualized approach, provides a practical framework for evaluation and triage at the bedside, and reviews concerns specific to all members of the interprofessional postresuscitation care team.

Accidental hypothermia-an update : The content of this review is endorsed by the International Commission for Mountain Emergency Medicine (ICAR MEDCOM)

BACKGROUND

This paper provides an up-to-date review of the management and outcome of accidental hypothermia patients with and without cardiac arrest.

METHODS

The authors reviewed the relevant literature in their specialist field. Summaries were merged, discussed and approved to produce this narrative review.

RESULTS

The hospital use of minimally-invasive rewarming for non-arrested, otherwise healthy, patients with primary hypothermia and stable vital signs has the potential to substantially decrease morbidity and mortality for these patients. Extracorporeal life support (ECLS) has revolutionised the management of hypothermic cardiac arrest, with survival rates approaching 100 % in some cases. Hypothermic patients with risk factors for imminent cardiac arrest (temperature <28 °C, ventricular arrhythmia, systolic blood pressure <90 mmHg), and those who have already arrested, should be transferred directly to an ECLS-centre. Cardiac arrest patients should receive continuous cardiopulmonary resuscitation (CPR) during transfer. If prolonged transport is required or terrain is difficult, mechanical CPR can be helpful. Delayed or intermittent CPR may be appropriate in hypothermic arrest when continuous CPR is impossible. Modern post-resuscitation care should be implemented following hypothermic arrest. Structured protocols should be in place to optimise pre-hospital triage, transport and treatment as well as in-hospital management, including detailed criteria and protocols for the use of ECLS and post-resuscitation care.

CONCLUSIONS

Based on new evidence, additional clinical experience and clearer management guidelines and documentation, the treatment of accidental hypothermia has been refined. ECLS has substantially improved survival and is the treatment of choice in the patient with unstable circulation or cardiac arrest.

Effect of Hypothermia and Targeted Temperature Management on Drug Disposition and Response Following Cardiac Arrest: A Comprehensive Review of Preclinical and Clinical Investigations

Targeted temperature management (TTM) has been shown to reduce mortality and improve neurological outcomes in out-of-hospital cardiac arrest (CA) patients and in neonates with hypoxic-ischemic encephalopathy (HIE). TTM has also been associated with adverse drug events in the critically ill patient due to its effect on drug pharmacokinetics (PKs) and pharmacodynamics (PDs). We aim to evaluate the current literature on the effect of TTM on drug PKs and PDs following CA. MEDLINE/PubMed databases were searched for publications, which include the MeSH terms hypothermia, drug metabolism, drug transport, P450, critical care, cardiac arrest, hypoxic-ischemic encephalopathy, pharmacokinetics, and pharmacodynamics between July 2006 and October 2015. Twenty-three studies were included in this review. The studies demonstrate that hypothermia impacts PK parameters and increases concentrations of cytochrome-P450-metabolized drugs in the cooling and rewarming phase. Furthermore, the current data demonstrate a combined effect of CA and hypothermia on drug PK. Importantly, these effects can last greater than 4-5 days post-treatment. Limited evidence suggests hypothermia-mediated changes in the Phase II metabolism and the Phase III transport of drugs. Hypothermia also has been shown to potentially decrease the effect of specific drugs at the receptor level. Therapeutic hypothermia, as commonly deployed/applied during TTM, alters PK, and elevates concentrations of several commonly used medications. Hypothermia-mediated effects are an important factor when dosing and monitoring patients undergoing TTM treatment.

Decreased Morphine Clearance in Neonates With Hypoxic Ischemic Encephalopathy Receiving Hypothermia

Morphine is commonly used in neonates with hypothermic ischemic encephalopathy (HIE) during therapeutic hypothermia to provide comfort and analgesia. However, pharmacokinetic data to support morphine dosing in this vulnerable population are lacking. A prospective, 2-center clinical pharmacokinetic study of morphine was conducted in 20 neonates (birthweight, 1.82-5.3 kg) with HIE receiving hypothermia. Morphine dosing was per standard of care at each center. Morphine and glucuronide metabolites (morphine-3-glucuronide and morphine-6-gluronide) were measured via a validated dried blood spot liquid chromatography-tandem mass spectrometry assay. From the available concentration data (n = 106 for morphine; n = 106 for each metabolite), a population pharmacokinetic model was developed using nonlinear mixed-effects modeling. The clearance of morphine and glucuronide metabolites was best predicted by birthweight allometrically scaled using an exponent of 1.23. In addition, the clearance of each glucuronide metabolite was influenced by serum creatinine. No other significant predictors of clearance or volume of distribution were found. For a 3.5-kg neonate, morphine clearance was 0.77 L/h (CV, 48%), and the steady-state volume of distribution was 8.0 L (CV, 49%). Compared with previous studies in full-term newborns without HIE, morphine clearance was markedly lower. Dosing strategies customized for this vulnerable population will be needed. Applying the final population pharmacokinetic model, repeated Monte Carlo simulations (n = 1000 per simulation) were performed to evaluate various morphine dosing strategies that optimized achievement of morphine concentrations between 10 and 40 ng/mL. An optimized morphine loading dose of 50 μg/kg followed by a continuous infusion of 5 μg/kg/h was predicted across birthweights.

Vasopressor requirement during targeted temperature management for out-of-hospital cardiac arrest caused by acute myocardial infarction without cardiogenic shock

Objective

We investigated whether patients with out-of-hospital cardiac arrest (OHCA) due to an acute myocardial infarction without cardiogenic shock required higher doses of vasopressors with low targeted temperature management (TTM) after return of spontaneous circulation.

Methods

We included consecutive comatose patients resuscitated from OHCA between January 2011 and December 2013. Patients with return of spontaneous circulation, regional wall motion abnormality on echocardiography, and coronary artery stenosis of ≥70% on percutaneous coronary artery angiography were enrolled. These patients received 36°C TTM or 33°C TTM following approval of TTM by patients’ next-of-kin (36°C and 33°C TTM groups, respectively). The cumulative vasopressor index was compared between groups.

Results

During induction phase, dose of vasopressors did not differ between groups. In the maintenance phase, the norepinephrine dose was 0.37±0.57 and 0.26±0.91 µg·kg^-1·min^-1 in the 33°C and 36°C TTM groups, respectively (P<0.01). During the rewarming phase, the norepinephrine and dopamine doses were 0.49±0.60 and 9.67±9.60 mcg·kg^-1·min^-1 in the 33°C TTM group and 0.14±0.46 and 3.13±7.19 mcg·kg^-1·min^-1 in the 36°C TTM group, respectively (P<0.01). The median cumulative vasopressor index was 8 (interquartile range, 3 to 8) and 4 (interquartile range, 0 to 8) in the 33°C and 36°C TTM groups, respectively (P=0.03).

Conclusion

In this study, patients with OHCA due to acute myocardial infarction without cardiogenic shock had an elevated vasopressor requirement with 33°C TTM compared to 36°C TTM during the maintenance and rewarming phases.

Role of enterohepatic recirculation in drug disposition: cooperation and complications

Enterohepatic recirculation (EHC) concerns many physiological processes and notably affects pharmacokinetic parameters such as plasma half-life and AUC as well as estimates of bioavailability of drugs. Also, EHC plays a detrimental role as the compounds/drugs are allowed to recycle. An in-depth comprehension of this phenomenon and its consequences on the pharmacological effects of affected drugs is important and decisive in the design and development of new candidate drugs. EHC of a compound/drug occurs by biliary excretion and intestinal reabsorption, sometimes with hepatic conjugation and intestinal deconjugation. EHC leads to prolonged elimination half-life of the drugs, altered pharmacokinetics and pharmacodynamics. Study of the EHC of any drug is complicated due to unavailability of the apposite model, sophisticated procedures and ethical concerns. Different in vitro and in vivo methods for studies in experimental animals and humans have been devised, each having its own merits and demerits. Involvement of the different transporters in biliary excretion, intra- and inter-species, pathological and biochemical variabilities obscure the study of the phenomenon. Modeling of drugs undergoing EHC has always been intricate and exigent models have been exploited to interpret the pharmacokinetic profiles of drugs witnessing multiple peaks due to EHC. Here, we critically appraise the mechanisms of bile formation, factors affecting biliary drug elimination, methods to estimate biliary excretion of drugs, EHC, multiple peak phenomenon and its modeling.

Sedation in Critically Ill Children with Respiratory Failure

This article discusses the rationale of sedation in respiratory failure, sedation goals, how to assess the need for sedation as well as effectiveness of interventions in critically ill children, with validated observational sedation scales. The drugs and non-pharmacological approaches used for optimal sedation in ventilated children are reviewed, and specifically the rationale for drug selection, including short- and long-term efficacy and safety aspects of the selected drugs. The specific pharmacokinetic and pharmacodynamic aspects of sedative drugs in the critically ill child and consequences for dosing are presented. Furthermore, we discuss different sedation strategies and their adverse events, such as iatrogenic withdrawal syndrome and delirium. These principles can guide clinicians in the choice of sedative drugs in pediatric respiratory failure.

A Literature Review of the Pharmacokinetics and Pharmacodynamics of Dobutamine in Neonates

Since its discovery in 1975 dobutamine has been used off-label for treating hemodynamic insufficiency in newborns and children. We present a structured literature review of pharmacokinetic and pharmacodynamic data for dobutamine in the pediatric population. Structured searches were conducted to identify relevant articles according to pre-defined inclusion criteria. Where possible, results for the pharmacodynamic and pharmacokinetic effect of dobutamine were reported as pooled data. Forty-six papers met the inclusion criteria. With regard to pharmacodynamic data a number of studies reported significant increases in a number of clinical parameters such as heart rate, blood pressure, cardiac output across a wide range of pediatric populations. With regard to pharmacokinetic data studies reported that the infusion rate was positively correlated to plasma dobutamine concentration. There was great variability with regard to dobutamine clearance between individuals and as to whether it followed first- or zero-order elimination kinetics. While the pharmacodynamic effects of dobutamine appear to reflect the pharmacological profile of the drug, the pharmacokinetic data are difficult to interpret due to inhomogeneity between study populations ages, comorbidities, dobutamine dosages and methodologies. High-quality prospective pharmacokinetic and pharmacodynamic data especially in newborns are urgently required prior to a large randomized study.

Mild hypothermia decreases the total clearance of glibenclamide after low dose administration in rats

BACKGROUND AND PURPOSE

Low dose glibenclamide exhibits pleiotropic protective effects in different central nervous system diseases. Previously, we have shown that mild hypothermia enhanced the efficacy of glibenclamide in the cultured cortical neuronal cells. This study aims to evaluate the impact of mild hypothermia on the pharmacokinetics of low dose glibenclamide in rats via its cytochrome P450 2C9 (CYP2C9) metabolic pathway.

METHODS

Male Sprague-Dawley rats were maintained at 37°C (normothermic group) or cooled to 33°C (hypothermic group). Glibenclamide (33μg/kg) or diclofenac (10mg/kg, a probe drug for assessing the activity of CYP2C9 which involves in glibenclamide and diclofenac metabolism in liver) were intravenously administered at 10min after stabilization of temperature. Plasma samples were collected at 9 different time points. Glibenclamide and diclofenac in sera were separated by liquid chromatography and quantified with tandem mass spectrometry.

RESULTS

Compared with normothermia, mild hypothermia significantly decreased the total clearance of glibenclamide (16.00±4.1-6.72±2.1mL/min/kg; p<0.01), and there was a non-significant trend in a slightly higher half-life, (1.64±0.34-2.71±1.7h, p=0.157). Area under the plasma concentration versus time curve (AUClast) in the hypothermic group was increased (33.2±11-77.8±18hng/mL, p<0.01). Moreover, mild hypothermia reduced the total clearance of diclofenac (10.33±1.53-7.20±1.66mL/min/kg, p<0.01), indicating that the CYP2C9 activity was compromised in reduced temperature.

CONCLUSION

Mild hypothermia reduced the total clearance of glibenclamide, probably via mediating the activity of CYP2C9. The impact of hypothermia in clinical application of glibenclamide should be considered.

Pilot evaluation of the population pharmacokinetics of bumetanide in term newborn infants with seizures

Recent experimental data suggest bumetanide as a possible therapeutic option in newborn infants with seizures after birth asphyxia. Because pharmacokinetic (PK) data are lacking in this population, who very often benefit from therapeutic cooling, which can modify the PK behavior of a drug, a PK study was conducted in term infants with seizures caused by hypoxic-ischemic encephalopathy. Fourteen infants were included, 13 of them being cooled. Forty-nine blood samples were available for the determination of the plasma concentration of bumetanide. Concentration-time data were analyzed by the use of a population approach performed with Monolix Software. Bumetanide was found to follow a 2-compartment model. The mean values were 0.063 L/h for clearance, 0.28 and 0.44 L for the central and peripheral distribution volumes, respectively, and 0.59 L/h for the distribution clearance. Birth body weight explained the interindividual variability of bumetanide clearance via an allometric model. No relationship was found between bumetanide exposure and its efficacy (reduction in seizure burden) or its toxicity (hearing loss). This study describes the first PK model of bumetanide in hypothermia-treated infants with seizures.

The effect of targeted temperature management on coagulation parameters and bleeding events after out-of-hospital cardiac arrest of presumed cardiac cause

AIMS

Targeted temperature management (TTM) is part of the standard treatment of comatose patients after out-of-hospital cardiac arrest (OHCA) to attenuate neurological injury. In other clinical settings, hypothermia promotes coagulopathy leading to an increase in bleeding and thrombosis tendency. Thus, concern has been raised as to whether TTM can be applied safely, as acute myocardial infarction requiring primary percutaneous coronary intervention (PCI) with the need of effective antiplatelet therapy is frequent following OHCA. This study investigated the influence of TTM at 33 or 36°C on various laboratory and coagulation parameters.

METHODS AND RESULTS

In this single-center predefined substudy of the TTM trial, 171 patients were randomized to TTM at either 33 or 36°C in the postresuscitation phase. The two subgroups were compared regarding standard laboratory coagulation parameters, thrombelastography (TEG), bleeding, and stent thrombosis events. Platelet counts were lower in the TTM33-group compared to TTM36 (p=0.009), but neither standard coagulation nor TEG-parameters showed any difference between the groups. TEG revealed a normocoagulable state in the majority of patients, while approximately 20% of the population presented as hypercoagulable. Adverse events included 38 bleeding events, one stent thrombosis, and one reinfarction, with no significant difference between the groups.

CONCLUSIONS

There was no evidence supporting the assumption that TTM at 33°C was associated with impaired hemostasis or increased the frequency of adverse bleeding and thrombotic events compared to TTM at 36°C. We found that TTM at either temperature can safely be applied in the postresuscitation phase after acute myocardial infarction and primary PCI.

Prolonged cooling duration mitigates myocardial and cerebral damage in cardiac arrest

BACKGROUND

The purpose of this study was to investigate the effect of prolonged cooling on cardiac and cerebral injury in animals under cardiac arrest.

METHODS

Adult male Wistar rats were equally randomized to normothermia, 5H1, 5H2, 7H1, 7H2, and 7H4 groups. The first number in the group name indicated ventricular fibrillation duration (minutes), the middle H indicated hypothermia, and the last number signified hypothermia duration (hours). Ventricular fibrillation was induced and untreated for 5 minutes (normothermia, 5H1, and 5H2) or 7 minutes (7H1, 7H2, and 7H4) followed by 1 minute of cardiopulmonary resuscitation followed by electric shocks. Hypothermia was initiated simultaneously with cardiopulmonary resuscitation initiation and maintained for 1 hour (5H1 and 7H1), 2 hours (5H2 and 7H2) or 4 hours (7H4).

RESULTS

There were 12 rats in each group. Compared with the 7H1 group, the 7H4 group had significantly better systolic function (dp/dt40) and cardiac output within the early postcardiac arrest period. Histologic examination disclosed less myocardial and hippocampal damage in the 7H4 group than the 7H1 group and in the 5H2 group than the 5H1 group. Plasma troponin I, fatty acid-binding protein, and S-100β concentrations were significantly lower in the 7H4 and 5H2 groups. The 7H4 and 5H2 groups survived statistically longer than the groups with shorter cooling duration.

CONCLUSION

Slightly prolonging hypothermia may mitigate myocardial and cerebral damage and improve survival and neurologic outcomes in a rat model of ventricular fibrillation cardiac arrest.

Management of neonatal morbidities during hypothermia treatment

Although the primary goal of therapeutic hypothermia is to improve the neurodevelopmental outcome in asphyxiated infants, optimal management of the full range of multi-organ system complications typically presented by such infants during cooling treatment is necessary for improvement of the overall outcome. For this reason, adequate knowledge of how cooling affects all organ systems of asphyxiated infants with multi-organ hypoxic-ischemic injury is essential. Adequate diagnostic resources, readily available subspecialty consultant services and trained multidisciplinary staff to monitor and manage multi-organ system complications in asphyxiated infants during therapeutic cooling must be ensured during implementation of a cooling program. As therapeutic hypothermia is being used more widely, centers should consider participation in national or international benchmarking of outcomes and short-term adverse events during cooling to facilitate continuous quality improvement efforts.

Ethics of drug research in the pediatric intensive care unit

Critical illness and treatment modalities change pharmacokinetics and pharmacodynamics of medications used in critically ill children, in addition to age-related changes in drug disposition and effect. Hence, to ensure effective and safe drug therapy, research in this population is urgently needed. However, conducting research in the vulnerable population of the pediatric intensive care unit (PICU) presents with ethical challenges. This article addresses the main ethical issues specific to drug research in these critically ill children and proposes several solutions. The extraordinary environment of the PICU raises specific challenges to the design and conduct of research. The need for proxy consent of parents (or legal guardians) and the stress-inducing physical environment may threaten informed consent. The informed consent process is challenging because emergency research reduces or even eliminates the time to seek consent. Moreover, parental anxiety may impede adequate understanding and generate misconceptions. Alternative forms of consent have been developed taking into account the unpredictable reality of the acute critical care environment. As with any research in children, the burden and risk should be minimized. Recent developments in sample collection and analysis as well as pharmacokinetic analysis should be considered in the design of studies. Despite the difficulties inherent to drug research in critically ill children, methods are available to conduct ethically sound research resulting in relevant and generalizable data. This should motivate the PICU community to commit to drug research to ultimately provide the right drug at the right dose for every individual child.

Dexmedetomidine and fentanyl exhibit temperature dependent effects on human respiratory cilia

BACKGROUND

Dexmedetomidine (dex) is commonly used in intensive care due to its effective sedation and analgesia with few adverse effects and minimal respiratory depression. However, we recently observed that exposing mouse epithelial respiratory cells to dex decreased ciliary beat frequency (CBF), suggesting dex may pose pulmonary risk.

OBJECTIVE

The purpose of this study is to determine the effects of dex at clinically relevant doses on CBF in human respiratory epithelia.

METHODS

Human nasal epithelial cilia were obtained from the inferior nasal turbinate with a rhinoprobe and placed in culture medium at 15°C and 37°C. At 5 and 30 min, video-microscopy was used to assess CBF, either without (control) or with different concentrations (1, 5, and 10 nM) of dex, fentanyl (fen), and dex + fen combination.

RESULTS

At 15°C, CBF was lower in the dex group compared to controls at 5 and 30 min. At 37°C, there was a significant increase in CBF with dex at 5 and 30 min, except for dex at 5 nM after 5 min, which showed a significant decrease. At 15°C the combination of dex + fen showed a positive interaction, causing less ciliary inhibition as expected. In contrast, no interaction between drugs was seen between dex and fen at 37°C.

CONCLUSION

At low temperatures, dex reduces CBF in human respiratory epithelia, whereas dex increases CBF at physiologic temperature in vitro. Whether these effects translate into clinical consequences during hypothermia, as with cardiopulmonary bypass surgery will require further studies.

Short- and long-term consequences of perinatal asphyxia: looking for neuroprotective strategies

Perinatal asphyxia constitutes a prototype of obstetric complications occurring when pulmonary oxygenation is delayed or interrupted. A primary insult is first produced by the length of the time without oxygenation, leading to hypoxia/ischemia and death if oxygenation is not promptly established. A second insult is produced by re-oxygenation, eliciting a cascade of biochemical events for restoring function, implying, however, improper homeostasis. The effects observed long after perinatal asphyxia can be explained by over-expression of sentinel proteins, such as poly(ADP-ribose) polymerase-1 (PARP-1), competing for oxidised nicotinamide adenine dinucleotide (NAD(+)) during re-oxygenation. Asphyxia also induces transcriptional activation of pro-inflammatory factors, including nuclear factor κB (NFκB) and its subunit p65, whose translocation to the nucleus is significantly increased in brain tissue from asphyxia-exposed animals, in tandem with PARP-1 overactivation, leading to the idea that sentinel protein inhibition constitutes a suitable therapeutic strategy. It is proposed that PARP-1 inhibition also down-regulates the expression of pro-inflammatory cytokines.Nicotinamide is a suitable PARP-1 inhibitor, whose effects have been studied in an experimental model of global perinatal asphyxia in rats, inducing the insult by immersing rat foetuses into a water bath for various periods of time. Following asphyxia, the pups are delivered, immediately treated, or given to surrogate dams for nursing, pending further experiments. Systemic administration of nicotinamide 1 h after the insult inhibited PARP-1 overactivity in peripheral and brain tissue, preventing several of the long-term consequences elicited by perinatal asphyxia, supporting the idea that it constitutes a lead for exploring compounds with similar or better pharmacological profiles.

Anticonvulsant effectiveness and hemodynamic safety of midazolam in full-term infants treated with hypothermia

BACKGROUND

Midazolam is used as an anticonvulsant in neonatology, including newborns with perinatal asphyxia treated with hypothermia. Hypothermia may affect the safety and effectiveness of midazolam in these patients.

OBJECTIVES

The objective was to evaluate the anticonvulsant effectiveness and hemodynamic safety of midazolam in hypothermic newborns and to provide dosing guidance.

METHODS

Hypothermic newborns with perinatal asphyxia and treated with midazolam were included. Effectiveness was studied using continuous amplitude-integrated electroencephalography. Hemodynamic safety was assessed using pharmacokinetic-pharmacodynamic modeling with plasma samples and blood pressure recordings (mean arterial blood pressure) under hypothermia.

RESULTS

No effect of therapeutic hypothermia on pharmacokinetics could be identified. Add-on seizure control with midazolam was limited (23% seizure control). An inverse relationship between the midazolam plasma concentration and mean arterial blood pressure could be identified. At least one hypotensive episode was experienced in 64%. The concomitant use of inotropes decreased midazolam clearance by 33%.

CONCLUSIONS

Under therapeutic hypothermia, midazolam has limited add-on clinical anticonvulsant effectiveness after phenobarbital administration. Due to occurrence of hypotension requiring inotropic support, midazolam is less suitable as a second-line anticonvulsant drug under hypothermia.

Managing moderate and severe pain in mountain rescue

AIMS

We aimed to describe evidence-based options for prehospital analgesia, and to offer practical advice to physicians and nonphysicians working in mountain rescue.

METHODS

A literature search was performed; the results and recommendations were discussed among the authors. Four authors considered a scenario. The final article was discussed and approved by the International Commission for Mountain Emergency Medicine (ICAR MEDCOM) in October 2013.

RESULTS AND RECOMMENDATIONS

Many health care providers fail to recognize, assess, and treat pain adequately. Assessment scales and treatment protocols should be implemented in mountain rescue services to encourage better management of pain. Specific training in assessing and managing pain is essential for all mountain rescuers. Persons administrating analgesics should receive appropriate detailed training. There is no ideal analgesic that will accomplish all that is expected in every situation. A range of drugs and delivery methods will be needed. Thus, an 'analgesic module' reflecting its users and the environment should be developed. The number of drugs carried should be reduced to a minimum by careful selection and, where possible, utilizing drugs with multiple delivery options. A strong opioid is recommended as the core drug for managing moderate or severe pain; a multimodal approach may provide additional benefits.

Prospective validation of neonatal vancomycin dosing regimens is urgently needed

BACKGROUND

Although vancomycin is frequently used to treat neonatal late-onset sepsis, there is no consensus on the optimal dosing regimen. Because many neonates needed dosing adaptation due to suboptimal trough values, the vancomycin dosing regimen in our neonatal department was changed during 2012.

OBJECTIVE

We aimed to document the need for validation of neonatal vancomycin dosing by exploring serum trough levels achieved using 2 published dosing regimens (previous regimen: based on postmenstrual age and serum creatinine and new regimen: based on postmenstrual age and postnatal age) and to identify covariates associated with suboptimal vancomycin trough levels (<10 mg/L).

METHODS

Routine therapeutic drug monitoring serum trough levels quantified after initiation of intravenous vancomycin therapy and clinical covariates were retrospectively collected. Median vancomycin trough levels of both dosing regimens were compared using the Mann-Whitney U test. The influence of continuous and dichotomous covariates on achieving a suboptimal trough level was explored using the Van Elteren test (stratified Mann-Whitney U test) and Mantel-Haenszel test (stratified χ(2) test), respectively. Covariates significant in monovariate analysis were subsequently included in a logistic regression analysis.

RESULTS

In total, 294 observations (median current weight 1870 g [range = 420-4863 g] and median postmenstrual age 35.07 weeks [range = 25.14-56.00 weeks]) were included. Using the previous and new dosing regimens, 66.3% and 76.2% of trough levels, respectively, were below 10 mg/L. Overall, suboptimal vancomycin trough values were significantly associated with lower weight (birth weight and current weight) and age (gestational age and postmenstrual age).

CONCLUSIONS

The majority of vancomycin trough levels in neonates achieved using 2 published dosing regimens did not reach the target of 10 mg/L. This illustrates the urgent need for prospective validation of neonatal vancomycin dosing regimens. We anticipate that dosing regimens integrating covariates reflecting general physiological maturation and renal maturation, as well as disease characteristics, could improve vancomycin exposure in neonates.

An update in postcardiac arrest management and prognosis in the era of therapeutic hypothermia

Prognostication of patients who remain comatose following successful resuscitation after cardiac arrest has long posed a challenge for the consulting neurologist. With increasing rates of early defibrillation, out-of-hospital cardiopulmonary resuscitation, and expanding use of therapeutic hypothermia, prognostication in hypoxic-ischemic encephalopathy has become an increasingly common consult for neurologists. Much of the data we previously relied upon for prognostication were taken from patients who were not treated with therapeutic hypothermia. In this review, we examine useful prognostic tools and markers, including the physical examination, evaluation of myoclonus, electroencephalogram monitoring, somatosensory-evoked potentials, biochemical markers of neuronal injury, and neuroimaging. Neurologists must avoid overly pessimistic prognostic statements regarding survival, awakening from coma, or future quality of life, as such statements may unduly influence decisions regarding the continuation of life-sustaining treatment. Conversely, continuation of aggressive medical management in a patient without any hope of awakening should also be avoided. Thus, an understanding of the utility and the limitations of these prognostic tools in the era of therapeutic hypothermia is essential.

Concentrations of remifentanil, propofol, fentanyl, and midazolam during rewarming from therapeutic hypothermia

BACKGROUND

The clearance of sedatives and analgesics may be reduced by therapeutic hypothermia. However, little is known about the concentrations of such drugs during rewarming. The aim of this study was to describe the serum concentrations of sedatives and analgesics during rewarming from therapeutic hypothermia.

METHODS

Blood samples were collected for quantification of drug concentrations in 22 patients given analgesia/sedation with either remifentanil/propofol or fentanyl/midazolam during rewarming from therapeutic hypothermia (33-34°C) after cardiac arrest. Samples for were drawn before (-2 h) and during rewarming (0-8 h). Linear mixed effects models were used to describe serum concentrations and adjust for rates of infusion during rewarming from therapeutic hypothermia.

RESULTS

Subjects with samples analyzed were remifentanil (n = 8), propofol (n = 14), fentanyl (n = 8), and midazolam (n = 8). Age, body mass index, and simplified acute physiology score II [mean (standard deviation)] were 64 (14.2) years, 27.3 (3.7) kg/m(2), and 69 (13.2), respectively. While the concentration of fentanyl was not significantly affected by temperature, concentrations of remifentanil, propofol, and midazolam decreased with core temperature by 16%, 12%, and 11% (mean values) from 33°C to 37°C after adjusting for rates of infusion, respectively.

CONCLUSION

Concentrations of remifentanil, propofol, and midazolam decreased during rewarming from therapeutic hypothermia when adjusting for rates of infusion. No changes were demonstrated for fentanyl.

Current status of hypothermia for hypoxemic ischemia of the newborn

This article reviews the pathophysiology of hypoxic-ischemic brain injury, and the impact of hypothermia as neuroprotection in the clinical setting. The results of trials performed in well resourced and mid and low resourced countries is presented. Infant and childhood outcome following hypothermia is provided. Biomarkers of outcome that are clinical, electrophysiological and imaging which will be helpful to clinicians are noted. Management of infants with encephalopathy, including safety of hypothermia is reviewed. The article concludes with knowledge gaps in neuroprotection and the future of hypothermia therapy.

Advances in management of neonatal seizures

Seizures are more common in the neonatal period than any other time in the human lifespan. A high index of suspicion for seizures should be maintained for infants who present with encephalopathy soon after birth, have had a stroke, central nervous system (CNS) infection or intracranial hemorrhage or have a genetic or metabolic condition associated with CNS malformations. Complicating the matter, most neonatal seizures lack a clinical correlate with only subtle autonomic changes and often no clinical indication at all. Over the last three decades, several tools have been developed to enhance the detection and treatment of neonatal seizures. The use of electroencephalography (EEG) and the later development of amplitude-integrated EEG (aEEG), allows for Neurologists and non-Neurologists alike, to significantly increase the sensitivity of seizure detection. When applied to the appropriate clinical setting, time to diagnosis and start of therapy is greatly reduced. Phenobarbital maintains the status of first-line therapy in worldwide use. However, newer anti-epileptic agents such as, levetiracetam, bumetanide, and topiramate are increasingly being applied to the neonatal population, offering the potential for seizure treatment with a significantly better side-effect profile. Seizures in premature infants, continue to confound clinicians and researchers alike. Though the apparent seizure burden is significant and there is an association between seizures and adverse outcomes, the two are not cleanly correlated. Compounding the issue, GABA-ergic anti-epileptic drugs are not only less effective in this age group due to reversed neuronal ion gradients but may cause harm. Selecting an appropriate treatment group remains a challenge.