Limited Ultrasound Protocol for Upper Extremity Peripherally Inserted Central Catheter Monitoring: A Pilot Study in the Neonatal Intensive Care Unit.

OBJECTIVES: To assess whether a limited ultrasound (US) scanning protocol to monitor the upper extremity peripherally inserted central catheter (PICC) location in neonates is feasible for experienced US operators. METHODS: A radiologist, who was blinded to the PICC location on chest radiography, performed 14 US scans on 11 neonates with upper extremity PICCs. A US machine with 13-6-MHz linear and 8-4-MHz phased array transducers was used for the examinations. RESULTS: The study population included 54% (n = 6) preterm infants, with 72% (n = 8) weighing less than 1500 g. The US location of the PICC was the same as the chest radiographic report in all 14 scans. A subclavicular long-axis view of the anterior chest visualized all PICCs in the subclavian or brachiocephalic veins. A parasternal long-axis right ventricular inflow view was able to visualize PICCs in the superior vena cava (SVC), and a subcostal long-axis view evaluated PICCs in the lower SVC and heart. The scanning time was location dependent: less than 5 minutes for PICCs in the brachiocephalic or subclavian vein and 5 to 10 minutes for PICCs in the SVC or heart. There were no desaturations below 90%, increases in the fraction of inspired oxygen need, or hypotension episodes during scanning. CONCLUSIONS: A limited US scanning protocol to determine the upper extremity PICC location is feasible. Our protocol needs to be tested in neonatal providers before further dissemination.

A Ferret Model of Encephalopathy of Prematurity.

There is an ongoing need for relevant animal models in which to test therapeutic interventions for infants with neurological sequelae of prematurity. The ferret is an attractive model species as it has a gyrified brain with a white-to-gray matter ratio similar to that in the human brain. A model of encephalopathy of prematurity was developed in postnatal day 10 (P10) ferret kits, considered to be developmentally equivalent to infants of 24-26 weeks' gestation. Cross-fostered P10 ferret kits received 5 mg/kg of lipopolysaccharide (LPS) before undergoing consecutive hypoxia-hyperoxia-hypoxia (60 min at 9%, 120 min at 60%, and 30 min at 9%). Control animals received saline vehicle followed by normoxia. The development of basic reflexes (negative geotaxis, cliff aversion, and righting) as well as gait coordination on an automated catwalk were assessed between P28 and P70, followed by ex vivo magnetic resonance imaging (MRI) and immunohistochemical analysis. Compared to controls, injured animals had slower overall reflex development between P28 and P40, as well as smaller hind-paw areas consistent with "toe walking" at P42. Injured animals also displayed significantly greater lateral movement during CatWalk assessment as a result of reduced gait coordination. Ex vivo MRI showed widespread white-matter hyperintensity on T2-weighted imaging as well as altered connectivity patterns. This coincided with white-matter dysmaturation characterized by increased intensity of myelin basic protein staining, white-matter thinning, and loss of oligodendrocyte transcription factor 2 (OLIG2)-positive cells. These results suggest both pathological and motor deficits consistent with premature white-matter injury. This newborn ferret model can therefore provide an additional platform to assess potential therapies before translation to human clinical trials.

Long-Term Neuropathological Changes Associated with Cerebral Palsy in a Nonhuman Primate Model of Hypoxic-Ischemic Encephalopathy.

BACKGROUND: Cerebral palsy (CP) is the most common motor disability in childhood, with a worldwide prevalence of 1.5-4/1,000 live births. Hypoxic-ischemic encephalopathy (HIE) contributes to the burden of CP, but the long-term neuropathological findings of this association remain limited. METHODOLOGY: Thirty-four term Macaca nemestrina macaques were included in this long-term neuropathological study: 9 control animals delivered by cesarean section and 25 animals with perinatal asphyxia delivered by cesarean section after 15-18 min of umbilical cord occlusion (UCO). UCO animals were randomized to saline (n = 11), therapeutic hypothermia (TH; n = 6), or TH + erythropoietin (Epo; n = 8). Epo was given on days 1, 2, 3, and 7. Animals had serial developmental assessments and underwent magnetic resonance imaging with diffusion tensor imaging at 9 months of age followed by necropsy. Histology and immunohistochemical (IHC) staining of brain and brainstem sections were performed. RESULTS: All UCO animals demonstrated and met the standard diagnostic criteria for human neonates with moderate-to-severe HIE. Four animals developed moderate-to-severe CP (3 UCO and 1 UCO + TH), 9 had mild CP (2 UCO, 3 UCO + TH, 3 UCO + TH + Epo, and 1 control), and 2 UCO animals died. None of the animals treated with TH + Epo died, had moderate-to-severe CP, or demonstrated signs of long-term neuropathological toxicity. Compared to animals grouped together as having no CP (no-CP; controls and mild CP only), animals with CP (moderate and severe) demonstrated decreased fractional anisotropy of multiple white-matter tracts including the corpus callosum and internal capsule, when using Tract-Based Spatial Statistics (TBSS). Animals with CP had decreased staining for cortical neurons and increased brainstem glial scarring compared to animals without CP. The cerebellar cell density of the internal granular layer and white matter was decreased in CP animals compared to that in control animals without CP. CONCLUSIONS/SIGNIFICANCE: In this nonhuman primate HIE model, animals treated with TH + Epo had less brain pathology noted on TBSS and IHC staining, which supports the long-term safety of TH + Epo in the setting of HIE. Animals that developed CP showed white-matter changes noted on TBSS, subtle histopathological changes in both the white and gray matter, and brainstem injury that correlated with CP severity. This HIE model may lend itself to further study of the relationship between brainstem injury and CP.

Systemic glycerol decreases neonatal rabbit brain and cerebellar growth independent of intraventricular hemorrhage.

BACKGROUND: Cerebellar hypoplasia is a common problem in preterm infants and infants suffering from intraventricular hemorrhage (IVH). To evaluate the effects of IVH on cerebellar growth and development, we used a neonatal rabbit model of systemic glycerol to produce IVH. METHODS: New Zealand White rabbit kits were surgically delivered 2 d preterm and treated with intraperitoneal glycerol (3.25-6.5 g/kg). Controls were born at term. IVH was documented by ultrasonography. Brain volumes determined by magnetic resonance imaging, cerebellar foliation, proliferation (Ki-67), and Purkinje cell density were assessed at 2 wk of life. Tissue glycerol and glutathione concentrations were measured. RESULTS: Glycerol increased IVH, subarachnoid hemorrhages, and mortality in a dose-dependent manner. Total cerebellar volumes, cerebellar foliation, and cerebellar proliferation were decreased in a dose-dependent manner. Glycerol accumulated rapidly in blood, brain, and liver and was associated with increased glutathione concentration. All of these results were independent of IVH status. CONCLUSION: Cerebellar hypoplasia was induced after glycerol administration in a dose-dependent manner. Given the rapid tissue accumulation of glycerol, dose-dependent decrease in brain growth, and lack of IVH effect on measured outcomes, we question the validity of this model because glycerol toxicity cannot be ruled out. A better physiological model of IVH is needed.

Concurrent erythropoietin and hypothermia treatment improve outcomes in a term nonhuman primate model of perinatal asphyxia.

BACKGROUND: Up to 65% of untreated infants suffering from moderate to severe hypoxic-ischemic encephalopathy (HIE) are at risk of death or major disability. Therapeutic hypothermia (HT) reduces this risk to approximately 50% (number needed to treat: 7-9). Erythropoietin (Epo) is a neuroprotective treatment that is promising as an adjunctive therapy to decrease HIE-induced injury because Epo decreases apoptosis, inflammation, and oxidative injury and promotes glial cell survival and angiogenesis. We hypothesized that HT and concurrent Epo will be safe and effective, improve survival, and reduce moderate-severe cerebral palsy (CP) in a term nonhuman primate model of perinatal asphyxia. METHODOLOGY: Thirty-five Macaca nemestrina were delivered after 15-18 min of umbilical cord occlusion (UCO) and randomized to saline (n = 14), HT only (n = 9), or HT+Epo (n = 12). There were 12 unasphyxiated controls. Epo (3,500 U/kg × 1 dose followed by 3 doses of 2,500 U/kg, or Epo 1,000 U/kg/day × 4 doses) was given on days 1, 2, 3, and 7. Timed blood samples were collected to measure plasma Epo concentrations. Animals underwent MRI/MRS and diffusion tensor imaging (DTI) at <72 h of age and again at 9 months. A battery of weekly developmental assessments was performed. RESULTS: UCO resulted in death or moderate-severe CP in 43% of saline-, 44% of HT-, and 0% of HT+Epo-treated animals. Compared to non-UCO control animals, UCO animals exhibit poor weight gain, behavioral impairment, poor cerebellar growth, and abnormal brain DTI. Compared to UCO saline, UCO HT+Epo improved motor and cognitive responses, cerebellar growth, and DTI measures and produced a death/disability relative risk reduction of 0.911 (95% CI -0.429 to 0.994), an absolute risk reduction of 0.395 (95% CI 0.072-0.635), and a number needed to treat of 2 (95% CI 2-14). The effects of HT+Epo on DTI included an improved mode of anisotropy, fractional anisotropy, relative anisotropy, and volume ratio as compared to UCO saline-treated infants. No adverse drug reactions were noted in animals receiving Epo, and there were no hematology, liver, or kidney laboratory effects. CONCLUSIONS/SIGNIFICANCE: HT+Epo treatment improved outcomes in nonhuman primates exposed to UCO. Adjunctive use of Epo combined with HT may improve the outcomes of term human infants with HIE, and clinical trials are warranted.

Neonatal subarachnoid hemorrhage disrupts multiple aspects of cerebellar development.

Over the past decade, survival rates for extremely low gestational age neonates (ELGANs; <28 weeks gestation) has markedly improved. Unfortunately, a significant proportion of ELGANs will suffer from neurodevelopmental dysfunction. Cerebellar hemorrhagic injury (CHI) has been increasingly recognized in the ELGANs population and may contribute to neurologic dysfunction; however, the underlying mechanisms are poorly understood. To address this gap in knowledge, we developed a novel model of early isolated posterior fossa subarachnoid hemorrhage (SAH) in neonatal mice and investigated both acute and long-term effects. Following SAH on postnatal day 6 (P6), we found significant decreased levels of proliferation with the external granular layer (EGL), thinning of the EGL, decreased Purkinje cell (PC) density, and increased Bergmann glial (BG) fiber crossings at P8. At P42, CHI resulted in decreased PC density, decreased molecular layer interneuron (MLI) density, and increased BG fiber crossings. Results from both Rotarod and inverted screen assays did not demonstrate significant effects on motor strength or learning at P35-38. Treatment with the anti-inflammatory drug Ketoprofen did not significantly alter our findings after CHI, suggesting that treatment of neuro-inflammation does not provide significant neuroprotection post CHI. Further studies are required to fully elucidate the mechanisms through which CHI disrupts cerebellar developmental programming in order to develop therapeutic strategies for neuroprotection in ELGANs.

Neonatal Subarachnoid Hemorrhage Disrupts Multiple Aspects of Cerebellar Development.

Over the past decade, survival rates for extremely low gestational age neonates (ELGANs; <28 weeks gestation) has markedly improved. Unfortunately, a significant proportion of ELGANs will suffer from neurodevelopmental dysfunction. Cerebellar hemorrhagic injury (CHI) has been increasingly recognized in the ELGANs population and may contribute to neurologic dysfunction; however, the underlying mechanisms are poorly understood. To address this gap in knowledge, we developed a novel model of early isolated posterior fossa subarachnoid hemorrhage (SAH) in neonatal mice and investigated both acute and long-term effects. Following SAH on postnatal day 6 (P6), we found significant decreased levels of proliferation with the external granular layer (EGL), thinning of the EGL, decreased Purkinje cell (PC) density, and increased Bergmann glial (BG) fiber crossings at P8. At P42, CHI resulted in decreased PC density, decreased molecular layer interneuron (MLI) density, and increased BG fiber crossings. Results from both Rotarod and inverted screen assays did not demonstrate significant effects on motor strength or learning at P35-38. Treatment with the anti-inflammatory drug Ketoprofen did not significantly alter our findings after CHI, suggesting that treatment of neuro-inflammation does not provide significant neuroprotection post CHI. Further studies are required to fully elucidate the mechanisms through which CHI disrupts cerebellar developmental programming in order to develop therapeutic strategies for neuroprotection in ELGANs.

Postnatal morphine administration alters hippocampal development in rats.

Morphine is frequently used as an analgesic and sedative in preterm infants. Adult rats exposed to morphine have an altered hippocampal neurochemical profile and decreased neurogenesis in the dentate gyrus of the hippocampus. To evaluate whether neonatal rats are similarly affected, rat pups were injected twice daily with 2 mg/kg morphine or normal saline from postnatal days 3 to 7. On postnatal day 8, the hippocampal neurochemical profile was determined using in vivo (1)H NMR spectroscopy. The mRNA and protein concentrations of specific analytes were measured in hippocampus, and cell division in dentate gyrus was assessed using bromodeoxyuridine. The concentrations of γ-aminobutyric acid (GABA), taurine, and myo-insotol were decreased, whereas concentrations of glutathione, phosphoethanolamine, and choline-containing compounds were increased in morphine-exposed rats relative to control rats. Morphine decreased glutamic acid decarboxylase enzyme levels and myelin basic protein mRNA expression in the hippocampus. Bromodeoxyuridine labeling in the dentate gyrus was decreased by 60-70% in morphine-exposed rats. These results suggest that recurrent morphine administration during brain development alters hippocampal structure.

Diffusion Tensor Imaging Changes Do Not Affect Long-Term Neurodevelopment following Early Erythropoietin among Extremely Preterm Infants in the Preterm Erythropoietin Neuroprotection Trial.

We aimed to evaluate diffusion tensor imaging (DTI) in infants born extremely preterm, to determine the effect of erythropoietin (Epo) on DTI, and to correlate DTI with neurodevelopmental outcomes at 2 years of age for infants in the Preterm Erythropoietin Neuroprotection (PENUT) Trial. Infants who underwent MRI with DTI at 36 weeks postmenstrual age were included. Neurodevelopmental outcomes were evaluated by Bayley Scales of Infant and Toddler Development (BSID-III). Generalized linear models were used to assess the association between DTI parameters and treatment group, and then with neurodevelopmental outcomes. A total of 101 placebo- and 93 Epo-treated infants underwent MRI. DTI white matter mean diffusivity (MD) was lower in placebo- compared to Epo-treated infants in the cingulate and occipital regions, and occipital white matter fractional isotropy (FA) was lower in infants born at 24-25 weeks vs. 26-27 weeks. These values were not associated with lower BSID-III scores. Certain decreases in clustering coefficients tended to have lower BSID-III scores. Consistent with the PENUT Trial findings, there was no effect on long-term neurodevelopment in Epo-treated infants even in the presence of microstructural changes identified by DTI.

Erythropoietin as a neuroprotectant for neonatal brain injury: animal models.

Prematurity and perinatal hypoxia-ischemia are common problems that result in significant neurodevelopmental morbidity and high mortality worldwide. The Vannucci model of unilateral brain injury was developed to model perinatal brain injury due to hypoxia-ischemia. Because the rodent brain is altricial, i.e., it develops postnatally, investigators can model either preterm or term brain injury by varying the age at which injury is induced. This model has allowed investigators to better understand developmental changes that occur in susceptibility of the brain to injury, evolution of brain injury over time, and response to potential neuroprotective treatments. The Vannucci model combines unilateral common carotid artery ligation with a hypoxic insult. This produces injury of the cerebral cortex, basal ganglia, hippocampus, and periventricular white matter ipsilateral to the ligated artery. Varying degrees of injury can be obtained by varying the depth and duration of the hypoxic insult. This chapter details one approach to the Vannucci model and also reviews the neuroprotective effects of erythropoietin (Epo), a neuroprotective treatment that has been extensively investigated using this model and others.