The relationship between systemic hemodynamic perturbations and periventricular-intraventricular hemorrhage--a historical perspective

Neurodevelopmental Outcome at Two Years for Preterm Infants With Intraventricular Hemorrhage: A Case-Control Study

BACKGROUND

High-grade intraventricular hemorrhage (IVH), including grade III and grade IV IVH, is known to impact neurodevelopmental outcome of preterm infants, but prognosis remains difficult to establish due to confounding factors and significant variations in the reported outcomes. The aim of this study was to compare the neurodevelopmental outcome of preterm infants with or without severe IVH.

METHODS

A retrospective case-control study was conducted including preterm infants with gestational age <32 weeks hospitalized between 2009 and 2017 in a level III neonatal intensive care unit. This study included 73 cases with high-grade IVH and 73 controls who were matched to cases, based on the same gestational age, birth weight, sex, and year of birth. The neurodevelopmental outcome was compared at two years of age corrected for prematurity between cases and controls. Neurodevelopmental impairment was defined as cerebral palsy, hearing deficiency, visual impairment, or developmental delay. Multivariate analysis was used to identify whether high-grade IVH was an independent risk factor for neurodevelopmental impairment.

RESULTS

In univariate analysis, high-grade IVH was associated with death or poor neurodevelopmental outcome at two years of age corrected for prematurity (odds ratio [OR], 16.3; 95% confidence interval [CI], 5.93 to 57.8; P < 0.001), and this association remained significant after adjusting for confounding factors including neonatal infection and bronchopulmonary dysplasia in multivariate analysis (OR, 8.71; 95% CI, 2.48 to 38.09; P = 0.002).

CONCLUSIONS

This study highlights the impact of high-grade IVH as an independent risk factor of poor neurodevelopmental outcomes in very preterm infants and suggests that early interventions could improve the prognosis of these infants.

The impact of prematurity and associated comorbidities on clinical outcomes in neonates with congenital heart disease

Prematurity is a common risk factor in children, affecting approximately 10% of live births, globally. It is more common in children with critical congenital heart disease (CCHD) and carries important implications in this group of patients. While outcomes have been improving over the years, even late preterm birth is associated with worse outcomes in children born with critical congenital heart disease compared to those without. Infants with both prematurity and CCHD are at particularly high risk for important comorbidities, including: necrotizing enterocolitis, intraventricular hemorrhage, white matter injury, neurodevelopmental anomalies and retinopathy of prematurity. Lesion-specific intensive care management of these infants, interventional and peri-operative management specifically tailored to their needs, and multidisciplinary care all have the potential to improve outcomes in this challenging group.

Neonatal Hypertension

Neonatal hypertension is uncommon but is becoming increasingly recognized. Normative blood pressure data are limited, as is research regarding the risks, treatment, and long-term outcomes. Therefore, there are no clinical practice guidelines and management is based on clinical judgment and expert opinion. Recognition of neonatal hypertension requires proper blood pressure measurement technique. When hypertension is present there should be a thorough clinical, laboratory, and imaging evaluation to promptly diagnose causes needing medical or surgical management. This review provides a practical overview for the practicing clinician regarding the identification, evaluation, and management of neonatal hypertension.

The role of the brain-sparing effect of growth-restricted fetuses in newborn germinal matrix/intraventricular hemorrhage

OBJECTIVES

The aim of the study was to evaluate the effect of the brain-sparing effect (BSE) of fetal growth restriction (FGR) in newborn germinal matrix/intraventricular hemorrhage (GM/IVH).

METHODS

A total of 320 patients who delivered prior to the 34th gestational week were analyzed from data records. 201 patients were divided into two groups according to cerebro-placental ratio (CPR): early fetal growth restriction (FGR) with abnormal CPR group (n=104) and appropriate for gestational age with normal Doppler group (control) (n=97). Using the normal middle cerebral artery (MCA) Doppler as a reference, multivariate logistic regression analysis was used to assess the association between the BSE and the primary outcome.

RESULTS

The rate of Grade I-II germinal matrix/intraventricular hemorrhage (GM/IVH) was 31(29.8%) in the group possessing early FGR with abnormal CPR and 7(7.2%) in the control group, showing a statistically significant difference. The rate of grade III-IV GM/IVH was 7(6.7%) in the group possessing early FGR with abnormal CPR and 2 (2.1%) in the control group, showing no statistically significant difference. We found that gestational age at delivery <32 weeks was an independent risk factor for GM/IVH. In addition, we found that other variables such as the presence of preeclampsia, fetal weight percentile <10, emergency CS delivery, 48-h completion after the first steroid administration and 24-h completion rate after MgSO₄ administration were not independently associated with the primary outcome.

CONCLUSIONS

Our results indicate that the rate of GM-IVH was increased in the group possessing early FGR with abnormal CPR; however, multivariate logistic regression analysis showed that BSE was not an independent risk factor for GM/IVH.

The hypertensive neonate

Hypertension in neonates is increasingly recognized because of improvements in neonatal intensive care that have led to improved survival of premature infants. Although normative data on neonatal blood pressure remain limited, several factors appear to be important in determining blood pressure levels in neonates, especially gestational age, birth weight and maternal factors. Incidence is around 1% in most studies and identification depends on careful blood pressure measurement. Common causes of neonatal hypertension include umbilical catheter associated thrombosis, renal parenchymal disease, and chronic lung disease, and can usually be identified with careful diagnostic evaluation. Given limited data on long-term outcomes and use of antihypertensive medications in these infants, clinical expertise may need to be relied upon to decide the best approach to treatment. This review will discuss these concepts and identify evidence gaps that should be addressed.

Erythropoietin Improves Atrophy, Bleeding and Cognition in the Newborn Intraventricular Hemorrhage

The germinal matrix-intraventricular hemorrhage (GM-IVH) is one of the most devastating complications of prematurity. The short- and long-term neurodevelopmental consequences after severe GM-IVH are a major concern for neonatologists. These kids are at high risk of psychomotor alterations and cerebral palsy; however, therapeutic approaches are limited. Erythropoietin (EPO) has been previously used to treat several central nervous system complications due to its role in angiogenesis, neurogenesis and as growth factor. In addition, EPO is regularly used to reduce the number of transfusions in the preterm infant. Moreover, EPO crosses the blood-brain barrier and EPO receptors are expressed in the human brain throughout development. To analyze the role of EPO in the GM-IVH, we have administered intraventricular collagenase (Col) to P7 mice, as a model of GM-IVH of the preterm infant. After EPO treatment, we have characterized our animals in the short (14 days) and the long (70 days) term. In our hands, EPO treatment significantly limited brain atrophy and ventricle enlargement. EPO also restored neuronal density and ameliorated dendritic spine loss. Likewise, inflammation and small vessel bleeding were also reduced, resulting in the preservation of learning and memory abilities. Moreover, plasma gelsolin levels, as a feasible peripheral marker of GM-IVH-induced damage, recovered after EPO treatment. Altogether, our data support the positive effect of EPO treatment in our preclinical model of GM-IVH, both in the short and the long term.

Neonatal care bundles are associated with a reduction in the incidence of intraventricular haemorrhage in preterm infants: a multicentre cohort study

OBJECTIVE

To investigate the effect of a nursing intervention bundle, applied during the first 72 hours of life, on the incidence of germinal matrix-intraventricular haemorrhage (GMH-IVH) in very preterm infants.

DESIGN

Multicentre cohort study.

SETTING

Two Dutch tertiary neonatal intensive care units.

PATIENTS

The intervention group consisted of 281 neonates, whereas 280 infants served as historical controls (gestational age for both groups <30 weeks).

INTERVENTIONS

After a training period, the nursing intervention bundle was implemented and applied during the first 72 hours after birth. The bundle consisted of maintaining the head in the midline, tilting the head of the incubator and avoidance of flushing/rapid withdrawal of blood and sudden elevation of the legs.

MAIN OUTCOME MEASURES

The incidence of GMH-IVH occurring and/or increasing after the first ultrasound (but within 72 hours), cystic periventricular leukomalacia and/or in-hospital death was the primary composite outcome measure. Logistic regression analysis was used to explore differences between groups.

RESULTS

The nursing intervention bundle was associated with a lower risk of developing a GMH-IVH (any degree), cystic periventricular leukomalacia and/or mortality (adjusted OR 0.42, 95% CI 0.27 to 0.65). In the group receiving the bundle, also severe GMH-IVH, cystic periventricular leukomalacia and/or death were less often observed (adjusted OR 0.54, 95% CI 0.33 to 0.91).

CONCLUSIONS

The application of a bundle of nursing interventions is associated with reduced risk of developing a new/progressive (severe) GMH-IVH, cystic periventricular leukomalacia and/or mortality in very preterm infants when applied during the first 72 hours postnatally.

L’imagerie cérébrale systématique du nouveau-né prématuré

L’imagerie cérébrale systématique pour déceler les lésions touchant les nouveau-nés prématurés est utilisée pour prédire le pronostic à long terme et déterminer les complications susceptibles de nécessiter une intervention. Même si l’imagerie par résonance magnétique peut être indiquée dans des situations particulières, l’échographie cérébrale est la technique la plus utilisée et demeure la meilleure modalité d’imagerie systématique en raison de sa portabilité et de sa facilité d’accès. L’échographie cérébrale systématique est recommandée pour tous les nouveau-nés venus au monde à 31+6 semaines d’âge gestationnel ou auparavant. Chez les nouveau-nés prématurés venus au monde entre 32+0 et 36+6 semaines d’âge gestationnel l’échographie cérébrale systématique n’est recommandée qu’en présence de facteurs de risque d’hémorragie intracrânienne ou d’ischémie. Il est conseillé d’obtenir une imagerie cérébrale de quatre à sept jours après la naissance pour déceler la plupart des hémorragies de la matrice germinale et des hémorragies intraventriculaires. Il est recommandé de reprendre l’imagerie entre quatre et six semaines de vie pour déceler les lésions de la substance blanche. Chez les nouveau-nés prématurés venus au monde avant 26 semaines d’âge gestationnel, il est recommandé de reprendre l’échographie cérébrale à l’âge équivalant au terme.

Routine imaging of the preterm neonatal brain

Routine brain imaging to detect injuries affecting preterm infants is used to predict long-term outcomes and identify complications that might necessitate an intervention. Although magnetic resonance imaging may be indicated in some specific cases, head ultrasound is the most widely used technique and, because of portability and ease of access, is the best modality for routine imaging. Routine head ultrasound examination is recommended for all infants born at or before 31+6 weeks gestation. For preterm neonates born between 32+0 to 36+6 weeks gestation, routine head ultrasound is recommended only in presence of risk factors for intracranial hemorrhage or ischemia. Brain imaging in the first 7 to 14 days postbirth is advised to detect most germinal matrix and intraventricular hemorrhages. Repeat imaging at 4 to 6 weeks of age is recommended to detect white matter injury.

Neurocritical care of premature infants

Neurocritical care is an approach of comprehensive care through multidisciplinary coordination and implementation of neuroprotective strategies to reduce the risk of neurologic injury among critically ill patients. Premature infants are at a special risk of sustaining brain injury and having adverse neurodevelopmental outcome. The pathogenesis of "encephalopathy of prematurity" is tightly linked to hemodynamic instability during postnatal transition, immaturity of the cerebral vascular bed and nervous system, and the commonly encountered inflammation in an intensive care setting. Clinical assessment aided by renewed monitoring techniques, together with therapies supported by best available evidence may provide opportunities to salvage these vulnerable brains. Indeed, to promote optimal brain development and to ensure neurodevelopmental intact survival is of imperial priority in the modern care of preterm infants.

The Role of Hemoglobin Oxidation Products in Triggering Inflammatory Response Upon Intraventricular Hemorrhage in Premature Infants

Intraventricular hemorrhage (IVH) is a frequent complication of prematurity that is associated with high neonatal mortality and morbidity. IVH is accompanied by red blood cell (RBC) lysis, hemoglobin (Hb) oxidation, and sterile inflammation. Here we investigated whether extracellular Hb, metHb, ferrylHb, and heme contribute to the inflammatory response after IVH. We collected cerebrospinal fluid (CSF) (n = 20) from premature infants with grade III IVH at different time points after the onset of IVH. Levels of Hb, metHb, total heme, and free heme were the highest in CSF samples obtained between days 0 and 20 after the onset of IVH and were mostly non-detectable in CSF collected between days 41 and 60 of post-IVH. Besides Hb monomers, we detected cross-linked Hb dimers and tetramers in post-IVH CSF samples obtained in days 0–20 and 21–40, but only Hb tetramers were present in CSF samples obtained after 41–60 days. Vascular cell adhesion molecule-1 (VCAM-1) and interleukin-8 (IL-8) levels were higher in CSF samples obtained between days 0 and 20 than in CSF collected between days 41 and 60 of post-IVH. Concentrations of VCAM-1, intercellular adhesion molecule-1 (ICAM-1), and IL-8 strongly correlated with total heme levels in CSF. Applying the identified heme sources on human brain microvascular endothelial cells revealed that Hb oxidation products and free heme contribute to the inflammatory response. We concluded that RBC lysis, Hb oxidation, and heme release are important components of the inflammatory response in IVH. Pharmacological interventions targeting cell-free Hb, Hb oxidation products, and free heme could have potential to limit the neuroinflammatory response following IVH.

Intracranial hemorrhage in neonates: A review of etiologies, patterns and predicted clinical outcomes

Intracranial hemorrhage (ICH) in neonates often results in devastating neurodevelopmental outcomes as the neonatal period is a critical window for brain development. The neurodevelopmental outcomes in neonates with ICH are determined by the maturity of the brain, the location and extent of the hemorrhage, the specific underlying etiology and the presence of other concomitant disorders. Neonatal ICH may result from various inherited and acquired disorders. We classify the etiologies of neonatal ICH into eight main categories: (1) Hemorrhagic stroke including large focal hematoma, (2) Prematurity-related hemorrhage, (3) Bleeding diathesis, (4) Genetic causes, (5) Infection, (6) Trauma-related hemorrhage, (7) Tumor-related hemorrhage and (8) Vascular malformations. Illustrative cases showing various imaging patterns that can be helpful to predict clinical outcomes will be highlighted. Potential mimics of ICH in the neonatal period are also reviewed.

Management of severe hypertension in the newborn

Blood pressure is considered a vital sign, as values too low or too high can be related with serious morbidity and mortality. In neonates, normal blood pressure values undergo rapid changes, especially in premature infants, making the recognition of abnormal blood pressures more challenging. Severe hypertension can occur in neonates and infants and is a medical emergency, often manifesting with congestive heart failure or other life-threatening complications. The cause or risk factors for the hypertension can usually be identified and may guide management. Most classes of antihypertensive medications have been used in the neonatal population. For severe hypertension, intravenous short-acting medications are preferred for a controlled reduction of blood pressure. In this article, we focus on identification, aetiology and management of severe hypertension in the newborn.

High-Frequency Oscillatory Ventilation in Adults With ARDS: Past, Present, and Future

High-frequency oscillatory ventilation (HFOV) is a unique mode of mechanical ventilation that uses nonconventional gas exchange mechanisms to deliver ventilation at very low tidal volumes and high frequencies. The properties of HFOV make it a potentially ideal mode to prevent ventilator-induced lung injury in patients with ARDS. Despite a compelling physiological basis and promising experimental data, large randomized controlled trials have not detected an improvement in survival with the use of HFOV, and its use as an early lung-protective strategy in patients with ARDS may be harmful. Nevertheless, HFOV still has an important potential role in the management of refractory hypoxemia. Careful attention should be paid to right ventricular function and lung stress when applying HFOV. This review discusses the physiological principles, clinical evidence, practical applications, and future prospects for the use of HFOV in patients with ARDS.

The Effect of Head Positioning and Head Tilting on the Incidence of Intraventricular Hemorrhage in Very Preterm Infants: A Systematic Review

BACKGROUND

Despite advances in neonatal intensive care, germinal matrix-intraventricular hemorrhage (GMH-IVH) remains a frequent, serious complication of premature birth. Neutral head position and head tilting have been suggested to reduce the risk of GMH-IVH in preterm infants during the first 72 h of life.

OBJECTIVE

The aim of this study was to provide a systematic review of the effect of neutral head positioning and head tilting on the incidence of GMH-IVH in very preterm infants (gestational age ≤30 weeks). In addition, we reviewed their effect on cerebral hemodynamics and oxygenation.

METHODS

Literature was searched (June 2016) in the following electronic databases: CINAHL, Embase, Medline, SCOPUS, and several trial registers.

RESULTS

One underpowered trial studied the effect of head positioning on the incidence of GMH-IVH. This randomized controlled trial enrolled 48 preterm infants and found no effect on the occurrence of GMH-IVH. Three observational studies investigated the effect of head rotation and/or tilting on cerebral oxygenation in 68 preterm infants in total. Their results suggest that cerebral oxygenation is not significantly affected by changes in head positioning. The effect of head positioning and/or tilting on cerebral hemodynamics was described in 2 observational studies of 28 preterm infants and found no significant effect.

CONCLUSIONS

There is insufficient evidence regarding the effect of head positioning and tilting on the incidence of GMH-IVH and cerebral hemodynamics and oxygenation in preterm infants. We recommend further research in this field, especially in extremely preterm and clinically unstable infants during the first postnatal days.

Mesenchymal Stromal Cell-Derived Extracellular Vesicles Protect the Fetal Brain After Hypoxia-Ischemia

Preterm neonates are susceptible to perinatal hypoxic-ischemic brain injury, for which no treatment is available. In a preclinical animal model of hypoxic-ischemic brain injury in ovine fetuses, we have demonstrated the neuroprotective potential of systemically administered mesenchymal stromal cells (MSCs). The mechanism of MSC treatment is unclear but suggested to be paracrine, through secretion of extracellular vesicles (EVs). Therefore, we investigated in this study the protective effects of mesenchymal stromal cell-derived extracellular vesicles (MSC-EVs) in a preclinical model of preterm hypoxic-ischemic brain injury. Ovine fetuses were subjected to global hypoxia-ischemia by transient umbilical cord occlusion, followed by in utero intravenous administration of MSC-EVs. The therapeutic effects of MSC-EV administration were assessed by analysis of electrophysiological parameters and histology of the brain. Systemic administration of MSC-EVs improved brain function by reducing the total number and duration of seizures, and by preserving baroreceptor reflex sensitivity. These functional protections were accompanied by a tendency to prevent hypomyelination. Cerebral inflammation remained unaffected by the MSC-EV treatment. Our data demonstrate that MSC-EV treatment might provide a novel strategy to reduce the neurological sequelae following hypoxic-ischemic injury of the preterm brain. Our study results suggest that a cell-free preparation comprising neuroprotective MSC-EVs could substitute MSCs in the treatment of preterm neonates with hypoxic-ischemic brain injury, thereby circumventing the potential risks of systemic administration of living cells.

SIGNIFICANCE

Bone marrow-derived mesenchymal stromal cells (MSCs) show promise in treating hypoxic-ischemic injury of the preterm brain. Study results suggest administration of extracellular vesicles, rather than intact MSCs, is sufficient to exert therapeutic effects and avoids potential concerns associated with administration of living cells. The therapeutic efficacy of systemically administered mesenchymal stromal cell-derived extracellular vesicles (MSC-EVs) on hypoxia-ischemia-induced injury was assessed in the preterm ovine brain. Impaired function and structural injury of the fetal brain was improved following global hypoxia-ischemia. A cell-free preparation of MSC-EVs could substitute for the cellular counterpart in the treatment of preterm neonates with hypoxic-ischemic brain injury. This may open new clinical applications for "off-the-shelf" interventions with MSC-EVs.

Transfontanellar duplex brain ultrasonography resistive indices as a prognostic tool in neonatal hypoxic-ischemic encephalopathy before and after treatment with therapeutic hypothermia

OBJECTIVE

Prior to therapeutic hypothermia (that is, cooling), transfontanellar duplex brain sonography resistive indices (RI) were studied as a bedside non-invasive measures of cerebral hemodynamics in neonates who suffered from hypoxic-ischemic encephalopathy (HIE). We compared pre- and post-cooling RI values and examined the relationships between RI values and specific long-term neurodevelopmental outcomes.

STUDY DESIGN

Transfontanellar duplex brain sonography, including RI, were obtained for 28 neonates prior to cooling and for 20 neonates following cooling. All RI values were sampled in the anterior cerebral artery at the beginning of each ultrasound study. Neurodevelopmental assessment was conducted between ages 20-32 months with the Mullen Scale of Early Learning. The relationships between pre- and post-cooling RI and cognitive and motor outcomes were studied.

RESULT

Neonates with RI values <0.60 prior to and following cooling were more likely to die or have severe neurodevelopmental disability by ages 20-32 months than those with RI>0.60. Lower RI values were associated with specific neurodevelopmental deficits in motor skill attainment.

CONCLUSION

Pre- and post-cooling transfontanellar duplex brain sonography RI values may be a useful prognostic tool, in conjunction with other clinical information, for neonates diagnosed with HIE. The results of this study suggest that further study of the prognostic value of RI values for short- and long-term outcomes is warranted.

Fast Doppler as a novel bedside measure of cerebral perfusion in preterm infants

BACKGROUND

Altered cerebral perfusion from impaired autoregulation may contribute to the morbidity and mortality associated with premature birth. We hypothesized that fast Doppler imaging could provide a reproducible bedside estimation of cerebral perfusion and autoregulation in preterm infants.

METHODS

This is a prospective pilot study using fast Doppler ultrasound to assess blood flow velocity in the basal ganglia of 19 subjects born at 26-32 wk gestation. Intraclass correlation provided a measure of test-retest reliability, and linear regression of cerebral blood flow velocity and heart rate or blood pressure allowed for estimations of autoregulatory ability.

RESULTS

The intraclass correlation when imaging in the first 48 h of life was 0.634. We found significant and independent correlations between the systolic blood flow velocity and both systolic blood pressure and heart rate (P = 0.015 and 0.012 respectively) only in the 26-28 wk gestational age infants in the first 48 h of life.

CONCLUSION

Our results suggest that fast Doppler provides reliable bedside measurements of cerebral blood flow velocity at the tissue level in premature infants, acting as a proxy for cerebral tissue perfusion. Additionally, autoregulation appears to be impaired in the extremely preterm infants, even within a normal range of blood pressures.

Periventricular/Intraventricular Hemorrhage and Neurodevelopmental Outcomes: A Meta-analysis

CONTEXT

Periventricular/intraventricular hemorrhage (PIVH) is a common short-term morbidity in preterm infants, but its long-term neurodevelopmental impact, particularly with mild PIVH, remains unclear.

OBJECTIVE

To systematically review and meta-analyze the neurodevelopmental outcomes of preterm infants ≤34 weeks' gestation with mild and severe PIVH, compared with no PIVH.

DATA SOURCES

Medline, Embase, CINAHL, and PsychINFO databases from January 2000 through June 2014.

STUDY SELECTION

Studies reporting long-term neurodevelopmental outcomes based on severity of PIVH were included.

DATA EXTRACTION

Study characteristics, inclusion/exclusion criteria, exposures, and outcome assessment data extracted independently by 2 coauthors.

RESULTS

The pooled unadjusted odds ratios of the primary outcome of death or moderate-severe neurodevelopmental impairment (NDI) were higher with both mild (1.48, 95% CI 1.26-1.73; 2 studies) and severe PIVH (4.72, 4.21-5.31; 3 studies); no studies reported adjusted odds ratios. Among survivors, odds of moderate-severe NDI were higher with mild and severe PIVH in both unadjusted (1.75, 1.40-2.20; 3 studies; 3.36, 3.06-3.68; 5 studies) and adjusted (1.39, 1.09-1.77; 3 studies; 2.44, 1.73-3.42; 2 studies) pooled analyses. Adjusted odds of cerebral palsy and cognitive delay were higher with severe but not mild PIVH.

LIMITATIONS

Only observational studies were included. Fifteen of 21 included studies had a moderate-high risk of bias.

CONCLUSIONS

Mild and severe PIVH are associated with progressively higher odds of death or moderate-severe NDI compared with no PIVH, but no studies adjusted for confounders. Among survivors, mild PIVH was associated with higher odds of moderate-severe NDI compared with no PIVH.

Head Position Change Is Not Associated with Acute Changes in Bilateral Cerebral Oxygenation in Stable Preterm Infants during the First 3 Days of Life

OBJECTIVE

Several recent intraventricular hemorrhage prevention bundles include midline head positioning to prevent potential disturbances in cerebral hemodynamics. We aimed to study the impact of head position change on regional cerebral saturations (SctO2) in preterm infants (< 30 weeks gestational age) during the first 3 days of life.

STUDY DESIGN

Bilateral SctO2 was measured by near-infrared spectroscopy. The infant's head was turned sequentially to each side from midline (baseline) in 30-minute intervals while keeping the body supine. Bilateral SctO2 before and after each position change were compared using paired t-test.

RESULTS

In relatively stable preterm infants (gestational age 26.5 ± 1.7 weeks, birth weight 930 ± 220 g; n = 20), bilateral SctO2 remained within normal range (71.1-75.3%) when the head was turned from midline position to either side.

CONCLUSION

Stable preterm infants tolerated brief changes in head position from midline without significant alternation in bilateral SctO2; the impact on critically ill infants needs further evaluation.

Overexpression of vascular endothelial growth factor in the germinal matrix induces neurovascular proteases and intraventricular hemorrhage

Intracranial hemorrhage in preterm neonates may result in neonatal mortality and functional disabilities, but its pathogenic mechanisms are poorly defined and better therapies are needed. We used a tetracycline-regulated transgenic system to test whether the induction of vascular endothelial growth factor (VEGF) in the germinal matrix leads to intracranial hemorrhage. This genetic strategy initially induced a dense network of loosely adjoined endothelial cells and pericytes near lateral ventricles, similar to the immature vascular rete in human fetal brains. Yet, this rich vascular network transformed into low-vasculature patches correlated with hemorrhage and caspase-3 activation near birth. Gene expression and biochemical analyses suggested that downstream mediators of VEGF in this network include transcriptional factors ETS1 and HIF2α (hypoxia-inducible factor 2α), components of the PDGFβ (platelet-derived growth factor β) and TGFβ (transforming growth factor-β) receptor signaling pathways, matrix metalloproteinase-9 (MMP-9), and cathepsins. Prenatal administration of glucocorticoids markedly reduced mortality and cerebral hemorrhage in mutant animals, as in human neonates. This protective effect was not due to blocking vasculogenesis, but was instead associated with inhibition of neurovascular proteases, notably MMP-9, cathepsin B, and caspase-3. Collectively, these results support a causative role of VEGF in perinatal cerebral hemorrhage and implicate its downstream proteases as potential therapeutic targets.

Early regular versus late selective poractant treatment in preterm infants born between 25 and 30 gestational weeks: a prospective randomized multicenter study

OBJECTIVE

Surfactant treatment in the early hours of life significantly decreases the rates of death and air leak, and increases survival without bronchopulmonary dysplasia (BPD) in preterm infants. We aimed to compare the impact of early surfactant (ES) administration to late selective (LS) treatment on neonatal outcomes in preterm infants.

METHODS

All preterm infants between 25 and 30 wks gestational age and who were not entubated in the delivery room and did not have any major congenital malformation or perinatal asphyxia were randomized to ES treatment (200 mg/kg Curosurf® administration in 1 hour after birth) or LS treatment (200 mg/kg Curosurf®administration in the first 6 h of life if needed). The patients were treated by nasal continuous positive airway pressure (nCPAP) treatment regardless of the surfactant requirement. Outcomes were the necessity of mechanical ventilation, nCPAP duration, the oxygen requirement duration, the rates of BPD, retinopathy of prematurity (ROP) and mortality, and the assessment of the following situations; (pneumothorax, patent ductus arteriosus (PDA), necrotizing enterocolitis (NEC), and intraventricular hemorrhage (IVH) ≥ grade III).

RESULTS

Among 159 infants enrolled in the study, 79 were randomized to ES and 80 to LS treatment groups. Thirty-five patients (44%) in the LS treatment group needed surfactant administration. Necessity of second dose surfactant administration was 8.9% in the ES treatment group. Although necessity of mechanical ventilation, nCPAP duration, oxygen need duration, rates of PDA, NEC, BPD, ROP stage >3 and mortality did not show a significant difference between groups, the ES treatment group had lower rates of pneumothorax and IVH ≥ grade III when compared to the LS treatment group.

CONCLUSIONS

ES treatment decreases IVH (≥ grade III) and pneumothorax rates but does not have any effect on BPD when compared to LS.

Heart rate-mediated blood pressure control in preterm fetal sheep under normal and hypoxic-ischemic conditions

BACKGROUND

The understanding of hypoxemia-induced changes in baroreflex function is limited and may be studied in a fetal sheep experiment before, during, and after standardized hypoxic conditions.

METHODS

Preterm fetal lambs were instrumented at 102 d gestation (term: 146 d). At 106 d, intrauterine hypoxia--ischemia was induced by 25 min of umbilical cord occlusion (UCO). Baroreflex-related fluctuations were calculated at 30-min intervals during the first week after UCO by transfer function (cross-spectral) analysis between systolic blood pressure (SBP) and R-R interval fluctuations, estimated in the low-frequency (LF, 0.04-0.15 Hz) band. LF transfer gain (baroreflex sensitivity) and delay (s) reflect the baroreflex function.

RESULTS

Baseline did not differ in LF transfer gain and delay between controls and the UCO group. In controls, LF gain showed postnatal increase. By contrast, LF gain gradually decreased in the UCO group, resulting in significantly lower values 4-7 d after UCO. In the UCO group, LF delay increased and differed significantly from controls.

CONCLUSION

Our results show that intrauterine hypoxia-ischemia results in reduced baroreflex sensitivity over a period of 7 d, indicating limited efficacy to buffer BP changes by adapting heart rate. Cardiovascular dysregulation may augment already present cerebral damage after systemic hypoxia-ischemia in the reperfusion period.

Neutral head positioning in premature infants for intraventricular hemorrhage prevention: an evidence-based review

With the advancement of neonatal medicine during the past several decades, premature and critically ill infants are living past the neonatal period and surviving. The survival of these infants at smaller birth weights and younger gestational ages puts them at an increased risk for intraventricular hemorrhages (IVHs). Although shifts in cerebral perfusion have been linked to the development of these brain bleeds, many seemingly benign care activities have been linked to changes in cerebral blood flow patterns, possibly contributing to IVHs. The purpose of this article is to evaluate the current evidence to determine if the practice of midline positioning for infants born less than 32 weeks gestation for possible IVH prevention is supported by the literature. Many of the researchers involved in these studies attributed the consequential venule leakage of blood to occlusion of the jugular venous drainage system following a turn in the position of the head. Additionally, the articles that examined the connection between the effects of head tilting on brain hemodynamics attributed changes on the infants' potential inability to autoregulate cerebral blood flow adequately. Both of these findings were linked to the development of IVHs. Based on physiologic data and expert opinion, the authors found support in the literature and recommend implementing a plan of care that includes midline head positioning for premature infants.

Cord blood erythropoietin and interleukin-6 for prediction of intraventricular hemorrhage in the preterm neonate

OBJECTIVE

To evaluate cord blood erythropoietin (EPO) and interleukin-6 (IL-6) levels to predict preterm infants at risk of developing intraventricular hemorrhage (IVH).

METHODS

Levels of umbilical cord EPO, acid-base status and IL-6 were analyzed in 116 consecutive, preterm newborns (GA at delivery: 29 [23-34 ] weeks) born to mothers who had a clinically indicated amniocentesis to rule out infection. Early-onset neonatal sepsis (EONS) was diagnosed using symptoms, hematological criteria and blood cultures.

RESULTS

IVH was diagnosed by cranial ultrasounds. The prevalence of IVH in our population was 25% (29/116). There was a direct relationship between cord blood EPO and cord blood IL-6 concentration (r = 0.225, p = 0.014), independent of GA at birth. Elevated cord blood EPO levels (r = 0.182, p = 0.016) and GA at birth (r =  -0.236, p = 0.004) remained significant independent factors associated with the risk of IVH, when evaluated with stepwise logistic regression analyses. Cord blood IL-6, pH, and EONS were not associated with IVH. These relationships remained following correction for GA at birth (p = 0.027).

CONCLUSIONS

Our results suggest that elevation in cord blood EPO may predict newborns at risk for IVH, independent of fetal inflammatory status. Further studies are warranted to confirm this association.