Association Between Seizures and Neurodevelopmental Outcome at Two and Five Years in Asphyxiated Newborns With Therapeutic Hypothermia

OBJECTIVE: To investigate the association between the presence and severity of seizures in asphyxiated newborns and their neurodevelopmental outcome at ages two and five years. METHODS: Retrospective data analysis from a prospectively collected multicenter cohort of 186 term-born asphyxiated newborns undergoing therapeutic hypothermia (TH) in 11 centers in the Netherlands and Belgium. Seizures were diagnosed by amplitude-integrated electroencephalography (EEG) and raw EEG signal reading up to 48 hours after rewarming. Neurodevelopmental outcome was assessed by standardized testing at age two and five years. Primary outcome was death or long-term neurodevelopmental impairment (NDI) including cerebral palsy. Associations were calculated using univariate and multivariate logistic regression analyses adjusting for Thompson score and a validated brain magnetic resonance imaging (MRI) score. RESULTS: Seventy infants (38%) had seizures during TH or rewarming, and 44 (63%) of these needed two or more antiseizure medications (ASMs). Overall mortality was 21%. Follow-up data from 147 survivors were available for 137 infants (93%) at two and for 94 of 116 infants (81%) at five years. NDI was present in 26% at two and five years. Univariate analyses showed a significant association between seizures and death or NDI, but this was no longer significant after adjusting for Thompson and MRI score in the multivariate analysis; this was also true for severe seizures (need for two or more ASMs) or seizures starting during rewarming. CONCLUSION: The presence or severity of seizures in newborns undergoing TH for hypoxic-ischemic encephalopathy was not independently associated with death or NDI up to age five years after adjusting for several confounders

Neonatal Gram Negative and Candida Sepsis Survival and Neurodevelopmental Outcome at the Corrected Age of 24 Months

Objectives: To evaluate the long term neurodevelopmental outcome of premature infants exposed to either gram- negative sepsis (GNS) or neonatal Candida sepsis (NCS), and to compare their outcome with premature infants without sepsis. Methods: Historical cohort study in a population of infants born at <30 weeks gestation and admitted to the Neonatal Intensive Care Unit (NICU) of the Academic Medical Center in Amsterdam during the period 1997-2007. Outcome of infants exposed to GNS or NCS and 120 randomly chosen uncomplicated controls (UC) from the same NICU were compared. Clinical data during hospitalization and neurodevelopmental outcome data (clinical neurological status; Bayley -test results and vision/hearing test results) at the corrected age of 24 months were collected. An association model with sepsis as the central determinant of either good or adverse outcome (death or severe developmental delay) was made, corrected for confounders using multiple logistic regression analysis. Results: Of 1362 patients, 55 suffered from GNS and 29 suffered from NCS; cumulative incidence 4.2% and 2.2%, respectively. During the follow-up period the mortality rate was 34% for both GNS and NCS and 5% for UC. The adjusted Odds Ratio (OR) [95% CI] for adverse outcome in the GNS group compared to the NCS group was 1.4 [0.4-4.9]. The adjusted ORs [95% CI] for adverse outcome in the GNS and NCS groups compared to the UC group were 4.8 [1.5-15.9] and 3.2 [0.7-14.7], respectively. Conclusions: We found no statistically significant difference in outcome at the corrected age of 24 months between neonatal GNS and NCS cases. Suffering from either gram -negative or Candida sepsis increased the odds for adverse outcome compared with an uncomplicated neonatal period

Population pharmacokinetics of vancomycin in term neonates with perinatal asphyxia treated with therapeutic hypothermia

Aims: Little is known about the population pharmacokinetics (PPK) of vancomycin in neonates with perinatal asphyxia treated with therapeutic hypothermia (TH). We aimed to describe the PPK of vancomycin and propose an initial dosing regimen for the first 48 h of treatment with pharmacokinetic/pharmacodynamic target attainment. Methods: Neonates with perinatal asphyxia treated with TH were included from birth until Day 6 in a multicentre prospective cohort study. A vancomycin PPK model was constructed using nonlinear mixed-effects modelling. The model was used to evaluate published dosing guidelines with regard to pharmacokinetic/pharmacodynamic target attainment. The area under the curve/minimal inhibitory concentration ratio of 400–600 mg*h/L was used as target range. Results: Sixteen patients received vancomycin (median gestational age: 41 [range: 38–42] weeks, postnatal age: 4.4 [2.5–5.5] days, birth weight: 3.5 [2.3–4.7] kg), and 112 vancomycin plasma concentrations were available. Most samples (79%) were collected during the rewarming and normothermic phase, as vancomycin was rarely initiated during the hypothermic phase due to its nonempirical use. An allometrically scaled 1-compartment model showed the best fit. Vancomycin clearance was 0.17 L/h, lower than literature values for term neonates of 3.5 kg without perinatal asphyxia (range: 0.20–0.32 L/h). Volume of distribution was similar. Published dosing regimens led to overexposure within 24 h of treatment. A loading dose of 10 mg/kg followed by 24 mg/kg/day in 4 doses resulted in target attainment. Conclusion: Results of this study suggest that vancomycin clearance is reduced in term neonates with perinatal asphyxia treated with TH. Lower dosing regimens should be considered followed by model-informed precision dosing.</p

Population Pharmacokinetics and Dosing Optimization of Ceftazidime in Term Asphyxiated Neonates during Controlled Therapeutic Hypothermia

Ceftazidime is an antibiotic commonly used to treat bacterial infections in term neonates undergoing controlled therapeutic hypothermia (TH) for hypoxic-ischemic encephalopathy after perinatal asphyxia. We aimed to describe the population pharmacokinetics (PK) of ceftazidime in asphyxiated neonates during hypothermia, rewarming, and normothermia and propose a population-based rational dosing regimen with optimal PK/pharmacodynamic (PD) target attainment. Data were collected in the PharmaCool prospective observational multicenter study. A population PK model was constructed, and the probability of target attainment (PTA) was assessed during all phases of controlled TH using targets of 100% of the time that the concentration in the blood exceeds the MIC (T.MIC) (for efficacy purposes and 100% T.4×MIC and 100% T.5×MIC to prevent resistance). A total of 35 patients with 338 ceftazidime concentrations were included. An allometrically scaled one-compartment model with postnatal age and body temperature as covariates on clearance was constructed. For a typical patient receiving the current dose of 100 mg/kg of body weight/day in 2 doses and assuming a worst-case MIC of 8 mg/L for Pseudomonas aeruginosa, the PTA was 99.7% for 100% T.MIC during hypothermia (33.7°C; postnatal age [PNA] of 2 days). The PTA decreased to 87.7% for 100% T.MIC during normothermia (36.7°C; PNA of 5 days). Therefore, a dosing regimen of 100 mg/kg/day in 2 doses during hypothermia and rewarming and 150 mg/kg/day in 3 doses during the following normothermic phase is advised. Higher-dosing regimens (150 mg/kg/day in 3 doses during hypothermia and 200 mg/kg/day in 4 doses during normothermia) could be considered when achievements of 100% T.4×MIC and 100% T.5×MIC are desired.</p

Population pharmacokinetics of vancomycin in term neonates with perinatal asphyxia treated with therapeutic hypothermia

Aims: Little is known about the population pharmacokinetics (PPK) of vancomycin in neonates with perinatal asphyxia treated with therapeutic hypothermia (TH). We aimed to describe the PPK of vancomycin and propose an initial dosing regimen for the first 48 h of treatment with pharmacokinetic/pharmacodynamic target attainment. Methods: Neonates with perinatal asphyxia treated with TH were included from birth until Day 6 in a multicentre prospective cohort study. A vancomycin PPK model was constructed using nonlinear mixed-effects modelling. The model was used to evaluate published dosing guidelines with regard to pharmacokinetic/pharmacodynamic target attainment. The area under the curve/minimal inhibitory concentration ratio of 400–600 mg*h/L was used as target range. Results: Sixteen patients received vancomycin (median gestational age: 41 [range: 38–42] weeks, postnatal age: 4.4 [2.5–5.5] days, birth weight: 3.5 [2.3–4.7] kg), and 112 vancomycin plasma concentrations were available. Most samples (79%) were collected during the rewarming and normothermic phase, as vancomycin was rarely initiated during the hypothermic phase due to its nonempirical use. An allometrically scaled 1-compartment model showed the best fit. Vancomycin clearance was 0.17 L/h, lower than literature values for term neonates of 3.5 kg without perinatal asphyxia (range: 0.20–0.32 L/h). Volume of distribution was similar. Published dosing regimens led to overexposure within 24 h of treatment. A loading dose of 10 mg/kg followed by 24 mg/kg/day in 4 doses resulted in target attainment. Conclusion: Results of this study suggest that vancomycin clearance is reduced in term neonates with perinatal asphyxia treated with TH. Lower dosing regimens should be considered followed by model-informed precision dosing.</p

Predictive Performance of a Gentamicin Pharmacokinetic Model in Term Neonates with Perinatal Asphyxia Undergoing Controlled Therapeutic Hypothermia

Background:Model validation procedures are crucial when population pharmacokinetic (PK) models are used to develop dosing algorithms and to perform model-informed precision dosing. We have previously published a population PK model describing the PK of gentamicin in term neonates with perinatal asphyxia during controlled therapeutic hypothermia (TH), which showed altered gentamicin clearance during the hypothermic phase dependent on gestational age and weight. In this study, the predictive performance and generalizability of this model were assessed using an independent data set of neonates with perinatal asphyxia undergoing controlled TH.Methods:The external data set contained a subset of neonates included in the prospective observational multicenter PharmaCool Study. Predictive performance was assessed by visually inspecting observed-versus-predicted concentration plots and calculating bias and precision. In addition, simulation-based diagnostics, model refitting, and bootstrap analyses were performed.Results:The external data set included 323 gentamicin concentrations of 39 neonates. Both the model-building and external data set included neonates from multiple centers. The original gentamicin PK model predicted the observed gentamicin concentrations with adequate accuracy and precision during all phases of controlled TH. Model appropriateness was confirmed with prediction-corrected visual predictive checks and normalized prediction distribution error analyses. Model refitting to the merged data set (n = 86 neonates with 935 samples) showed accurate estimation of PK parameters.Conclusions:The results of this external validation study justify the generalizability of the gentamicin dosing recommendations made in the original study for neonates with perinatal asphyxia undergoing controlled TH (5 mg/kg every 36 or 24 h with gestational age 36-41 and 42 wk, respectively) and its applicability in model-informed precision dosing.</p

Predictive Performance of a Gentamicin Pharmacokinetic Model in Term Neonates with Perinatal Asphyxia Undergoing Controlled Therapeutic Hypothermia

Background:Model validation procedures are crucial when population pharmacokinetic (PK) models are used to develop dosing algorithms and to perform model-informed precision dosing. We have previously published a population PK model describing the PK of gentamicin in term neonates with perinatal asphyxia during controlled therapeutic hypothermia (TH), which showed altered gentamicin clearance during the hypothermic phase dependent on gestational age and weight. In this study, the predictive performance and generalizability of this model were assessed using an independent data set of neonates with perinatal asphyxia undergoing controlled TH.Methods:The external data set contained a subset of neonates included in the prospective observational multicenter PharmaCool Study. Predictive performance was assessed by visually inspecting observed-versus-predicted concentration plots and calculating bias and precision. In addition, simulation-based diagnostics, model refitting, and bootstrap analyses were performed.Results:The external data set included 323 gentamicin concentrations of 39 neonates. Both the model-building and external data set included neonates from multiple centers. The original gentamicin PK model predicted the observed gentamicin concentrations with adequate accuracy and precision during all phases of controlled TH. Model appropriateness was confirmed with prediction-corrected visual predictive checks and normalized prediction distribution error analyses. Model refitting to the merged data set (n = 86 neonates with 935 samples) showed accurate estimation of PK parameters.Conclusions:The results of this external validation study justify the generalizability of the gentamicin dosing recommendations made in the original study for neonates with perinatal asphyxia undergoing controlled TH (5 mg/kg every 36 or 24 h with gestational age 36-41 and 42 wk, respectively) and its applicability in model-informed precision dosing.</p

Pharmacokinetics of morphine in encephalopathic neonates treated with therapeutic hypothermia

Objective Morphine is a commonly used drug in encephalopathic neonates treated with therapeutic hypothermia after perinatal asphyxia. Pharmacokinetics and optimal dosing of morphine in this population are largely unknown. The objective of this study was to describe pharmacokinetics of morphine and its metabolites morphine-3-glucuronide and morphine-6-glucuronide in encephalopathic neonates treated with therapeutic hypothermia and to develop pharmacokinetics based dosing guidelines for this population. Study design Term and near-term encephalopathic neonates treated with therapeutic hypothermia and receiving morphine were included in two multicenter cohort studies between 2008-2010 (SHIVER) and 2010-2014 (PharmaCool). Data were collected during hypothermia and rewarming, including blood samples for quantification of morphine and its metabolites. Parental informed consent was obtained for all participants. Results 244 patients (GA mean (sd) 39.8 (1.6) weeks, BW mean (sd) 3,428 (613) g, male 61.5%) were included. Morphine clearance was reduced under hypothermia (33.5 degrees C) by 6.89%/degrees C (95% CI 5.37%/degrees C-8.41%/degrees C, p<0.001) and metabolite clearance by 4.91%/degrees C (95% CI 3.53%/degrees C-6.22%/degrees C, p<0.001) compared to normothermia (36.5 degrees C). Simulations showed that a loading dose of 50 mu g/kg followed by continuous infusion of 5 mu g/kg/h resulted in morphine plasma concentrations in the desired range (between 10 and 40 mu g/L) during hypothermia. Conclusions Clearance of morphine and its metabolites in neonates is affected by therapeutic hypothermia. The regimen suggested by the simulations will be sufficient in the majority of patients. However, due to the large interpatient variability a higher dose might be necessary in individual patients to achieve the desired effect

Phenobarbital, midazolam pharmacokinetics, effectiveness, and drug-drug interaction in asphyxiated neonates undergoing therapeutic hypothermia

Background: Phenobarbital and midazolam are commonly used drugs in (near-)term neonates treated with therapeutic hypothermia for hypoxic-ischaemic encephalopathy, for sedation, and/or as anti-epileptic drug. Phenobarbital is an inducer of cytochrome P450 (CYP) 3A, while midazolam is a CYP3A substrate. Therefore, co-treatment with phenobarbital might impact midazolam clearance. Objectives: To assess pharmacokinetics and clinical anti-epileptic effectiveness of phenobarbital and midazolam in asphyxiated neonates and to develop dosing guidelines. Methods: Data were collected in the prospective multicentre PharmaCool study. In the present study, neonates treated with therapeutic hypothermia and receiving midazolam and/or phenobarbital were included. Plasma concentrations of phenobarbital and midazolam including its metabolites were determined in blood samples drawn on days 2–5 after birth. Pharmacokinetic analyses were performed using non-linear mixed effects modelling; clinical effectiveness was defined as no use of additional anti-epileptic drugs. Results: Data were available from 113 (phenobarbital) and 118 (midazolam) neonates; 68 were treated with both medications. Only clearance of 1-hydroxy midazolam was influenced by hypothermia. Phenobarbital co-administration increased midazolam clearance by a factor 2.3 (95% CI 1.9–2.9, p < 0.05). Anticonvulsant effectiveness was 65.5% for phenobarbital and 37.1% for add-on midazolam. Conclusions: Therapeutic hypothermia does not influence clearance of phenobarbital or midazolam in (near-)term neonates with hypoxic-ischaemic encephalopathy. A phenobarbital dose of 30 mg/kg is advised to reach therapeutic concentrations. Phenobarbital co-administration significantly increased midazolam clearance. Should phenobarbital be substituted by non-CYP3A inducers as first-line anticonvulsant, a 50% lower midazolam maintenance dose might be appropriate to avoid excessive exposure during the first days after birth. © 2019 The Author(s) Published by S. Karger AG, Base

Population pharmacokinetics of vancomycin in term neonates with perinatal asphyxia treated with therapeutic hypothermia

Aims: Little is known about the population pharmacokinetics (PPK) of vancomycin in neonates with perinatal asphyxia treated with therapeutic hypothermia (TH). We aimed to describe the PPK of vancomycin and propose an initial dosing regimen for the first 48 h of treatment with pharmacokinetic/pharmacodynamic target attainment. Methods: Neonates with perinatal asphyxia treated with TH were included from birth until Day 6 in a multicentre prospective cohort study. A vancomycin PPK model was constructed using nonlinear mixed-effects modelling. The model was used to evaluate published dosing guidelines with regard to pharmacokinetic/pharmacodynamic target attainment. The area under the curve/minimal inhibitory concentration ratio of 400–600 mg*h/L was used as target range. Results: Sixteen patients received vancomycin (median gestational age: 41 [range: 38–42] weeks, postnatal age: 4.4 [2.5–5.5] days, birth weight: 3.5 [2.3–4.7] kg), and 112 vancomycin plasma concentrations were available. Most samples (79%) were collected during the rewarming and normothermic phase, as vancomycin was rarely initiated during the hypothermic phase due to its nonempirical use. An allometrically scaled 1-compartment model showed the best fit. Vancomycin clearance was 0.17 L/h, lower than literature values for term neonates of 3.5 kg without perinatal asphyxia (range: 0.20–0.32 L/h). Volume of distribution was similar. Published dosing regimens led to overexposure within 24 h of treatment. A loading dose of 10 mg/kg followed by 24 mg/kg/day in 4 doses resulted in target attainment. Conclusion: Results of this study suggest that vancomycin clearance is reduced in term neonates with perinatal asphyxia treated with TH. Lower dosing regimens should be considered followed by model-informed precision dosing