Management of neonatal morbidities during hypothermia treatment

Cardiac Dysfunction in Neonatal HIE Is Associated with Increased Mortality and Brain Injury by MRI

OBJECTIVE

Describe the association between cardiac dysfunction and death or moderate-to-severe abnormalities on brain magnetic resonance imaging (MRI) in neonates undergoing therapeutic hypothermia for hypoxic ischemic encephalopathy (HIE).

STUDY DESIGN

Retrospective study in neonates with moderate or severe HIE undergoing therapeutic hypothermia between 2008 and 2017. Primary outcome was death or moderate-to-severe brain injury using the Barkovich score. Conventional and speckle-tracking echocardiography measures were extracted from available echocardiograms to quantify right (RV) and left (LV) ventricular functions.

RESULTS

A total of 166 newborns underwent therapeutic hypothermia of which 53 (36.5%) had echocardiography performed. Ten (19%) died prior to hospital discharge, and 11 (26%) had moderate-to-severe brain injury. There was no difference in chronologic age at echocardiography between the normal and adverse outcome groups (22 [±19] vs. 28 [±21] hours, p = 0.35). Cardiac findings in newborns with abnormal outcome included lower systolic and diastolic blood pressure (BP) at echocardiography (p = 0.004) and decreased tricuspid annular plane systolic excursion (a marker of RV systolic function; p = 0.01), while the ratio of systolic pulmonary artery (PA) pressure to systolic BP indicated isosystemic pressures (>2/3 systemic) in both groups. A multilogistic regression analysis, adjusting for weight and seizure status, indicated an association between abnormal outcome and LV function by longitudinal strain, as well as by ejection fraction.

CONCLUSION

Newborns who died or had moderate-to-severe brain injury had a higher incidence of cardiac dysfunction but similar PA pressures when compared with those who survived with mild or no MRI abnormalities.

KEY POINTS

· Newborns with HIE with functional LV/RV dysfunction are at risk for death or brain injury.. · All neonates with HIE had elevated pulmonary pressure, but neonates with poor outcome had RV dysfunction.. · When evaluating newborns with HIE by echocardiography, beyond estimation of pulmonary pressure, it is important to assess biventricular function..

Process variations between Swiss units treating neonates with hypoxic-ischemic encephalopathy and their effect on short-term outcome

OBJECTIVE

To compare therapeutic hypothermia (TH) treatment of term and near-term neonates with hypoxic-ischemic encephalopathy (HIE) between neonatal units.

STUDY DESIGN

Population-based, retrospective analysis of TH initiation and maintenance, and of diagnostic imaging. The comparison between units was based on crude data analysis, indirect standardization, and adjusted logistic regression.

RESULTS

TH was provided to 570 neonates with HIE between 2011 and 2018 in 10 Swiss units. We excluded 121 off-protocol cooled neonates to avoid selection bias. Of the remaining 449 neonates, the outcome was favorable to international benchmarks, but there were large unit-to-unit variations in baseline perinatal data and TH management. A total of 5% neonates did not reach target temperature within 7 h (3-10% between units), and 29% experienced over- or undercooling (0-38%).

CONCLUSION

Although the neonates had favorable short-term outcomes, areas for improvement remain for Swiss units in both process and outcome measures.

Does Severity of Brain Injury on Magnetic Resonance Imaging Predict Short-Term Outcome in Neonates Who Received Therapeutic Hypothermia?

OBJECTIVE

 The National Institute of Child Health and Human Development (NICHD) magnetic resonance imaging (MRI) pattern of brain injury is a known biomarker of childhood outcome following therapeutic hypothermia for neonatal hypoxic-ischemic encephalopathy (HIE). However, usefulness of this classification has not been evaluated to predict short-term outcomes. The study aimed to test the hypothesis that infants with NICHD MRI pattern of severe hypoxic-ischemic brain injury will be sicker with more severe asphyxia-induced multiorgan dysfunction resulting in prolonged length of stay (LOS) following therapeutic hypothermia. We also evaluated the role of other risk factors which may prolong LOS.

STUDY DESIGN

 We retrospectively reviewed the medical records of 71 consecutively cooled neonates to examine the ability of MRI patterns of brain injury to predict the LOS. A neuroradiologist masked to outcomes classified the patterns of brain injury on MRI as per NICHD. Pattern 2A (basal ganglia thalamic, internal capsule, or watershed infarction), 2B (2A with cerebral lesions), and 3 (hemispheric devastation) of brain injury was deemed "severe injury."

RESULTS

 Out of 71 infants, 59 surviving infants had both MRI and LOS data. LOS was higher for infants who had Apgar's score of ≤5 at 10 minutes, severe HIE, seizures, coagulopathy, or needed vasopressors or inhaled nitric oxide, or had persistent feeding difficulty, or remained intubated following cooling. However, median LOS did not differ between the infants with and without MRI pattern of severe injury (15 days, interquartile range [IQR]: 9-28 vs. 12 days, IQR: 10-20; p = 0.4294). On multivariate linear regression analysis, only persistent feeding difficulty (β coefficient = 11, p = 0.001; or LOS = 11 days longer if had feeding difficulty) and ventilator days (β coefficient 1.7, p < 0.001; or LOS increased 1.7 times for each day of ventilator support) but not the severity of brain injury predicted LOS.

CONCLUSION

 Unlike neurodevelopmental outcome, LOS is not related to severity of brain injury as defined by the NICHD.

KEY POINTS

· The NICHD pattern of brain injury on MRI predicts neurodevelopmental outcome following hypothermia treatment for neonatal HIE.. · LOS did not differ between the infants with and without MRI patterns of severe injury.. · The severity of brain injury as defined by the NICHD was not predictive of the LOS following therapeutic hypothermia..

System Specific Effects of Therapeutic Hypothermia with Neonatal Encephalopathy: Pearls for Clinicians

Neonatal encephalopathy (NE) is defined as a condition of impaired neurological function often caused by a peripartum event that impairs gas exchange resulting in hypoxia, hypercapnia, cerebral ischemia, and metabolic acidosis. NE is a significant cause of neonatal morbidity and mortality. Therapeutic hypothermia (TH) is the standard of care for the treatment of moderate and severe NE and has significantly improved long-term outcomes for affected infants. There are extensive systemic physiologic effects associated with TH that clinicians need to be aware of to optimize care for these infants. There is a paucity of literature that comprehensively identifies causal relationships between the physiologic and biochemical effects of TH. This can leave neonatal clinicians devoid of a comprehensive understanding of the medical management of NE. Therefore, this article seeks to help fill this gap, improve clinician knowledge base, and ultimately improve the care of infants undergoing TH.

Multiple Organ Dysfunction During Therapeutic Cooling of Asphyxiated Infants

The main purpose of therapeutic cooling is neuroprotection of asphyxiated infants with significant hypoxic-ischemic encephalopathy. However, to improve the overall outcome, it is necessary to properly manage the full range of multiple organ system complications found in asphyxiated infants undergoing therapeutic cooling. Every physiologic process in an asphyxiated infant can potentially be affected by the cooling treatment. The purpose of this review is to discuss the effect of cooling on neonatal physiology in the current recommended cooling range and the management thereof.

A Case Study of Severe Hypercalcemia Secondary to Subcutaneous Fat Necrosis: A Diagnosis of Exclusion

Subcutaneous fat necrosis (SCFN) is a rare complication, usually occurring in otherwise healthy full-term infants who have experienced some level of trauma that causes ischemic injury to adipose tissue. Tissue injury usually occurs in areas of the body that are exposed to excessive pressure as during delivery. Tissue injury has also been described secondary to therapeutic cooling. This case study presents an infant who received whole body cooling for hypoxic ischemic injury and later developed severe hypercalcemia at one month of age without the skin lesions consistent with SCFN. The differential diagnosis for hypercalcemia and how it relates to SCFN is presented, as well as clinical presentation, treatment, and prognosis.

Population Pharmacokinetics of Gentamicin in Neonates with Hypoxemic-Ischemic Encephalopathy Receiving Controlled Hypothermia

OBJECTIVE

Identify population pharmacokinetics and pharmacodynamic target attainment of gentamicin in neonates with hypoxic-ischemic encephalopathy (HIE) undergoing controlled hypothermia (CH).

DESIGN

Prospective open-label pharmacokinetic study. Gentamicin concentrations were modeled and dosing regimens simulated for a 5000-patient neonatal population with HIE receiving CH using PMetrics, a nonparametric, pharmacometric modeling, and simulation package for R.

SETTING

A 189-bed children's tertiary care teaching hospital.

RESULTS

Twelve patients, 5 (42%) females and 7 (58%) males, met inclusion criteria with a median gestation age of 39.9 weeks (interquartile range [IQR] 38.5-40.2 wks) and a median birthweight (BW) of 3.3 kg (IQR 3.1-3.7 kg). Gentamicin concentrations were best described by a two-compartment model with first-order elimination with BW as a covariate on volume of distribution (Vd). The mean total body population clearance (CL) was 2.2 ± 0.7 ml/minute/kg, and the volume of the central compartment was 0.44 ± 0.06 L/kg. The R² , bias, and precision for the observed versus population predicted model were 0.917, 1.15, and 10.9 μg/ml; the R² , bias, and precision for the observed versus individual predicted model were 0.982, -0.132, and 0.932 μg/ml, respectively. The calculated mean population estimate for the total Vd was 0.96 ± 0.4 L/kg. The dosing regimen that most consistently produced a maximum concentration (C_max ) in the range of 10-12 mg/L with a minimum concentration (C_min ) level less than 2 mg/L was 5 mg/kg/dose given every 36 hours.

CONCLUSION

These data suggest the population pharmacokinetics of gentamicin in neonates with HIE receiving CH have an increase in gentamicin CL and are different from previous reports in neonates with HIE not receiving CH and/or neonates without HIE. This analysis suggests a dosing regimen of 5 mg/kg/dose every 36 hours results in a gentamicin C_max within the range of 10-12 mg/L with a C_min lower than 2 mg/L, which is appropriate for treating susceptible gram-negative organisms with minimum inhibitory concentrations of 1 mg/L or lower.