Cumulative index of exposure to hypocarbia and hyperoxia as risk factors for periventricular leukomalacia in low birth weight infants

Evaluation of Neonatal Cerebral Circulation Under Hypoxic Ischemic Risk Factors Based on Quantitative Analysis of Cerebral Veins with Magnetic Resonance Susceptibility Weighted Imaging

PURPOSE

To observe the regulation of cerebral circulation in vivo based on image segmentation algorithms for deep learning in medical imaging to automatically detect and quantify the neonatal deep medullary veins (DMVs) on susceptibility weighted imaging (SWI) images. To evaluate early cerebral circulation self-rescue for neonates undergoing risk of cerebral hypoxia-ischaemia in vivo.

METHODS

SWI images and clinical data of 317 neonates with or without risk of cerebral hypoxia-ischaemia were analyzed. Quantitative parameters showing the number, width, and curvature of DMVs were obtained using an image segmentation algorithm.

RESULTS

The number of DMVs was greater in males than in females (p < 0.01), and in term than in preterm infants (p = 0.001). The width of DMVs was greater in term than in preterm infants (p < 0.01), in low-risk than in high-risk group (p < 0.01), and in neonates without intracranial extracerebral haemorrhage (ICECH) than with ICECH (p < 0.05). The curvature of DMVs was greater in term than in preterm infants (P < 0.05). The width of both bilateral thalamic veins and anterior caudate nucleus veins were positively correlated with the number of DMVs; the width of bilateral thalamic veins was positively correlated with the width of DMVs.

CONCLUSION

The DMVs quantification based on image segmentation algorithm may provide more detailed and stable quantitative information in neonate. SWI vein quantification may be an observable indicator for in vivo assessment of cerebral circulation self-regulation in neonatal hypoxic-ischemic brain injury.

Capnography waveforms: basic interpretation in neonatal intensive care

End-tidal capnography can provide useful clinical information displayed on the ventilator screen or bedside monitor. It is important that clinicians can assess and utilise this information to assist in identifying underlying complications and pulmonary pathology. Sudden change or loss of the CO2 waveform can act as a safety measure in alerting clinicians of a dislodged or blocked endotracheal tube, considering the concurrent flow and volume waveforms. Visual pattern recognition by the clinicians of commonly seen waveform traces may act as an adjunct to other modes of ventilatory monitoring techniques. Waveforms traces can aid clinical management, help identify cases of ventilation asynchrony between the infant and the ventilator. We present some common clinical scenarios where tidal capnography can be useful in the timely identification of pulmonary complication and for practical troubleshooting at the cot-side.

Protecting the brain of the micropreemie

Advances in perinatal care have seen substantial improvements in survival without disability for extremely preterm infants. Protecting the developing brain and reducing neurodevelopmental sequelae of extremely preterm birth are strategic priorities for both research and clinical care. A number of evidence-based interventions exist for neuroprotection in micropreemies, inclusive of prevention of preterm birth and multiple births with implantation of only one embryo during in vitro fertilisation, as well as antenatal care to optimize fetal wellbeing, strategies for supporting neonatal transition, and neuroprotective developmental care. Avoidance of complications that trigger ischemia and inflammation is vital for minimizing brain dysmaturation and injury, particularly of the white matter. Neurodevelopmental surveillance, early diagnosis of cerebral palsy and early intervention are essential for optimizing long-term outcomes and quality of life. Research priorities include further evaluation of putative neuroprotective agents, and investigation of common neonatal interventions in trials adequately powered to assess neurodevelopmental outcome.

The dimensions of white matter injury in preterm neonates

White matter injury (WMI) represents a frequent form of parenchymal brain injury in preterm neonates. Several dimensions of WMI are recognized, with distinct neuropathologic features involving a combination of destructive and maturational anomalies. Hypoxia-ischemia is the main mechanism leading to WMI and adverse white matter development, which result from injury to the oligodendrocyte precursor cells. Inflammation might act as a potentiator for WMI. A combination of hypoxia-ischemia and inflammation is frequent in several neonatal comorbidities such as postnatal infections, NEC and bronchopulmonary dysplasia, all known contributors to WMI. White matter injury is an important predictor of adverse neurodevelopmental outcomes. When WMI is detected on neonatal brain imaging, a detailed characterization of the injury (pattern of injury, severity and location) may enhance the ability to predict outcomes. This clinically-oriented review will provide an overview of the pathophysiology and imaging diagnosis of the multiple dimensions of WMI, will explore the association between postnatal complications and WMI, and will provide guidance on the signification of white matter anomalies for motor and cognitive development.

Carbon dioxide monitoring in the newborn infant

Carbon dioxide (CO₂ ) monitoring is vital during mechanical ventilation of newborn infants, as morbidity increases when CO₂ levels are inappropriate. Our aim was to review the uses and limitations of such noninvasive monitoring methods. Colorimetry is primarily utilized during resuscitation to determine whether successful intubation has occurred. False negative and positive results can however lead to delays in detecting tracheal versus esophageal intubation. Transcutaneous carbon dioxide sensors have limited use during resuscitation, but can be utilized to provide continuous trend data during on-going ventilation. End-tidal capnography can provide clinicians with quantitative end-tidal CO₂ (EtCO₂ ) values and a continuous real-time capnogram waveform trace. These devices are becoming more widely accepted for use in the neonatal population as the new devices are lightweight with minimal additional dead space. Nevertheless, they have been reported to have variable accuracy when compared to arterial CO₂ measurements, however, divergence of results may be related to disease severity rather than technological limitations. During resuscitation EtCO₂ can be detected by capnography more rapidly than by colorimetry. Furthermore, capnography can be currently utilized in neonatal research settings to determine the physiological dead space and ventilation inhomogeneity, and thus has potential to be beneficial to clinical care. In conclusion, novel modes of noninvasive carbon dioxide monitoring can be safely and reliably utilized in newborn infants during mechanical ventilation. Future randomized trials should aim to address which device provides the most optimal form of monitoring in different clinical contexts.

Neuroprotection of the Perinatal Brain by Early Information of Cerebral Oxygenation and Perfusion Patterns

Abnormal patterns of cerebral perfusion/oxygenation are associated with neuronal damage. In preterm neonates, hypoxemia, hypo-/hypercapnia and lack of cerebral autoregulation are related to peri-intraventricular hemorrhages and white matter injury. Reperfusion damage after perinatal hypoxic ischemia in term neonates seems related with cerebral hyperoxygenation. Since biological tissue is transparent for near infrared (NIR) light, NIR-spectroscopy (NIRS) is a noninvasive bedside tool to monitor brain oxygenation and perfusion. This review focuses on early assessment and guiding abnormal cerebral oxygenation/perfusion patterns to possibly reduce brain injury. In term infants, early patterns of brain oxygenation helps to decide whether or not therapy (hypothermia) and add-on therapies should be considered. Further NIRS-related technical advances such as the use of (functional) NIRS allowing simultaneous estimation and integrating of heart rate, respiration rate and monitoring cerebral autoregulation will be discussed.

Spontaneous hypocarbia without mechanical ventilation in preterm infants with cystic periventricular leukomalacia

AIM

Hypocarbia induced by mechanical ventilation has been considered a main cause of cystic periventricular leukomalacia (cPVL). However, hypocarbia may occur spontaneously in response to intracellular metabolic acidosis. We aimed to assess whether hypocarbia is more common during mechanical respiratory support than during spontaneous ventilation in infants with cPVL.

METHOD

In this single-centre, retrospective chart analysis, we compared partial pressure of carbon dioxide (pCO₂ ) during the first 96 hours of life in infants with cPVL during endotracheal mechanical ventilation, non-invasive respiratory support, or without respiratory support.

RESULTS

Cystic periventricular leukomalacia was diagnosed in 23 infants born between 2006 and 2017. Gestational age was 24 weeks in two infants and ranged between 28 and 32 weeks in 21 infants. In these 21 infants, pCO₂ less than 35 mm Hg during the first 96 ours of life accounted for 9/60 (15%) measurements during endotracheal mechanical ventilation, 16/116 (14%) during non-invasive respiratory support and 14/42 (33%) in infants without respiratory support (P = .014).

CONCLUSION

In our series of infants with cPVL, hypocarbia was more common without respiratory support than during endotracheal mechanical ventilation and non-invasive respiratory support. This would suggest that hypocarbia is a symptom rather than a cause of cPVL in these infants.

Metabolic acidosis rather than hypo/hypercapnia in the first 72 hours of life associated with intraventricular hemorrhage in preterm neonates

Aim: Safe limits of arterial partial pressure of carbon dioxide (PaCO₂) and acidosis in premature infants are not well defined. Both respiratory and systemic illness along with center-specific ventilation strategies contribute to PaCO₂ fluctuations and acid-base imbalances during the critical time period of first 72 h of life. This study evaluated the association between early blood gas parameters and intraventricular hemorrhage (IVH) in preterm infants.Methods: This retrospective observational study included neonates with a gestational age (GA) of ≤29 wks, who had at least 7 blood gas analysis done within the first 72 h of life. By adjusting for known variables that predispose to IVH, multivariable logistic regression analysis was used to study the association of PaCO₂ and acid-base measures with the risk of IVH.Results: Between 2013-2016, among 272 neonates who met inclusion criteria and were assessed for IVH on cranial ultrasound within first week of life, 101 neonates [mean GA of 25 ± 1.5 wks] had IVH and 171 neonates [mean GA of 25 ± 1.6 wks] had normal scans. After adjustment for confounding variables, higher values of maximum lactate (OR = 1.18, 95% CI = 1.1-1.3, p < .0001) and maximum base deficit (OR = 1.19, 95% CI = 1.1-1.2, p < .0001) within 72 h of life increased the likelihood of any grade of IVH. However, time-weighted average PaCO₂, maximum and minimum PaCO₂ had no statistically significant effect on the risk of IVH. The relationship remained unchanged even when moderate-severe IVH was considered as the primary outcome.Conclusion: Severe metabolic acidosis rather than hypo/hypercapnia during the first 72 h of life was associated with higher odds of IVH in infants born at ≤29 wks of gestation. Future studies determining levels of PaCO₂ that is safe for premature brain would need to control for the metabolic component of acidosis.

Continuous Noninvasive Carbon Dioxide Monitoring in Neonates: From Theory to Standard of Care

Ventilatory support may affect the short- and long-term neurologic and respiratory morbidities of preterm infants. Ongoing monitoring of oxygenation and ventilation and control of adequate levels of oxygen, pressures, and volumes can decrease the incidence of such adverse outcomes. Use of pulse oximetry became a standard of care for titrating oxygen delivery, but continuous noninvasive monitoring of carbon dioxide (CO₂) is not routinely used in NICUs. Continuous monitoring of CO₂ level may be crucial because hypocarbia and hypercarbia in extremely preterm infants are associated with lung and brain morbidities, specifically bronchopulmonary dysplasia, intraventricular hemorrhage, and cystic periventricular leukomalacia. It is shown that continuous monitoring of CO₂ levels helps in maintaining stable CO₂ values within an accepted target range. Continuous monitoring of CO₂ levels can be used in the delivery room, during transport, and in infants receiving invasive or noninvasive respiratory support in the NICU. It is logical to hypothesize that this will result in better outcome for extremely preterm infants. In this article, we review the different noninvasive CO₂ monitoring alternatives and devices, their advantages and disadvantages, and the available clinical data supporting or negating their use as a standard of care in NICUs.

Investigation of the relationship between umbilical cord pH and intraventricular hemorrhage of infants delivered preterm

OBJECTIVE

We measured the level of pH gases in premature infants at birth, and examined the relationship between brain ultrasonography on the third and seventh day after birth. A case-control study conducted at the Neonatal Intensive Care Unit (NICU) of Shahid Akbar Abadi Hospital, Iran, during the years 2016-2017.

METHODS

All premature infants who were admitted to NICU were enrolled in the current study. At birth, a blood gas sample was taken from the umbilical cord of the infants. On the third and seventh day after birth, an ultrasound of the brain of each neonate was performed by a radiologist. The umbilical cord was evaluated for blood gases in 72 neonates (mostly boys).

RESULTS

Sixty-six newborns had normal sonography, and 16.7% (12 cases) had anomalies. A total of 75% of the 8 infants with intravenous bleeding were girls, which were significantly different from those in the non-hemodynamic group (62.5% male) (P 0.049). However, the type of delivery, mean weight, height, head circumference, the circumference of the chest, and Apgar score did not differ between the two groups. Mean pH, HCO3- and PCO2 in umbilical cord blood gas samples were not significantly different between the two groups with or without intraventricular hemorrhage (IVH). Although it was not related to gender and type of delivery in newborns.

CONCLUSION

Blood gases do not help in determining the occurrence of IVH in infants. Nevertheless, it is associated with immaturity and fetal age.

Neurodevelopmental outcomes of extremely preterm infants in southern China: A multicenter study

OBJECTIVE

To assess treatment outcomes and associated factors of extremely preterm infants (EPIs) in GuangXi, China.

METHODS

This was a retrospective study consisting of 131 eligible cases with gestational age (GA) between 22 and 28 weeks, and infants were followed until 18-24 months. Data including clinical characteristics, perinatal factors and after-birth conditions were collected from the neonatal intensive care unit in 10 hospitals in Guangxi from January 1st 2010 until May 31st 2016.

RESULTS

During that period, 307 EPIs were born in the hospitals. 137 infants died in hospital after their parents decided to withdraw clinical treatment, and 11 infants died despite full resuscitation was provided. Of the 159 surviving infants, 28 infants were lost to follow-up. In total, 131 infants who survived and were presented to follow-up at 18-24 months of age were enrolled into this study. Of the 131 infants evaluated at 18-24 months follow-up, 47 (35.9%) were diagnosed with neurodevelopmental disability (ND), and 84 (64%) demonstrated on tract motor and language skills. The incidence of chorioamnionitis, early onset sepsis (EOS), bronchopulmonary dysplasia (BPD) were all higher in the group of infants who were diagnosed with ND compared to those with normal motor language development (NML), the duration of mechanical ventilation (MV) was longer in ND group, and the higher incidence of ND was seen in the smaller GA babies (p < 0.05). Adjusted the BPD severity, GA was a protective factor of neurodevelopmental outcome (combined OR = 0.338, 95% CI: 0.145-0.791). In EPIs with moderate BPD and severe BPD, chorioamnionitis was a risk factor of ND (OR = 10.313 and 5.778，respectively, 95% CI: 1.389-6.486 and 1.444-23.119, respectively). The Logistic regression analysis showed that GA (OR = 0.207, 95%CI = 0.047-0.917) was a protective factor for ND, and chorioamnionitis (OR = 6.010, 95%CI: 1.331-27.138), moderate-to-severe BPD (OR = 4.285, 95%CI: 1.495-12.287), the duration of MV (OR = 3.508, 95%CI: 2.077-5.926) were independent risk factors for ND in EPIs.

CONCLUSIONS

Chorioamnionitis, moderate-to-severe BPD, and the duration of MV were associated with neurodevelopmental disability in EPIs. The smaller the GA, the higher incidence of neurodevelopmental disability.

Glutamate Transport and Preterm Brain Injury

Preterm birth complications are the leading cause of child death worldwide and a top global health priority. Among the survivors, the risk of life-long disabilities is high, including cerebral palsy and impairment of movement, cognition, and behavior. Understanding the molecular mechanisms of preterm brain injuries is at the core of future healthcare improvements. Glutamate excitotoxicity is a key mechanism in preterm brain injury, whereby the accumulation of extracellular glutamate damages the delicate immature oligodendrocytes and neurons, leading to the typical patterns of injury seen in the periventricular white matter. Glutamate excitotoxicity is thought to be induced by an interaction between environmental triggers of injury in the perinatal period, particularly cerebral hypoxia-ischemia and infection/inflammation, and developmental and genetic vulnerabilities. To avoid extracellular build-up of glutamate, the brain relies on rapid uptake by sodium-dependent glutamate transporters. Astrocytic excitatory amino acid transporter 2 (EAAT2) is responsible for up to 95% of glutamate clearance, and several lines of evidence suggest that it is essential for brain functioning. While in the adult EAAT2 is predominantly expressed by astrocytes, EAAT2 is transiently upregulated in the immature oligodendrocytes and selected neuronal populations during mid-late gestation, at the peak time for preterm brain injury. This developmental upregulation may interact with perinatal hypoxia-ischemia and infection/inflammation and contribute to the selective vulnerability of the immature oligodendrocytes and neurons in the preterm brain. Disruption of EAAT2 may involve not only altered expression but also impaired function with reversal of transport direction. Importantly, elevated EAAT2 levels have been found in the reactive astrocytes and macrophages of human infant post-mortem brains with severe white matter injury (cystic periventricular leukomalacia), potentially suggesting an adaptive mechanism against excitotoxicity. Interestingly, EAAT2 is suppressed in animal models of acute hypoxic-ischemic brain injury at term, pointing to an important and complex role in newborn brain injuries. Enhancement of EAAT2 expression and transport function is gathering attention as a potential therapeutic approach for a variety of adult disorders and awaits exploration in the context of the preterm brain injuries.

A population-based study of cystic white matter injury on ultrasound in very preterm infants born over two decades in Nova Scotia, Canada

OBJECTIVE

To identify the temporal trends, risk factors and outcomes of cystic white matter injury (WMI) detected by ultrasound in a population-based cohort of very preterm infants (VPI) with a minimal risk of selection bias.

STUDY DESIGN

All live-born VPIs between 22 and < 31 weeks gestational age born in Nova Scotia, Canada from 1993 to 2013.

RESULTS

Cystic WMI was identified in 87 (7%) out of 1184 eligible infants. The gestational age and mortality adjusted prevalence of cystic WMI decreased over time (p = 0.04). In multivariable analysis, chorioamnionitis, antenatal steroids, admission hypothermia, ventilator support, inotropes, and non-Coagulase-negative Staphylococcal and fungal infections were independently associated with cystic WMI. Cerebral palsy was the most common disability in the survivors, however, half of the survivors had none or mild disability.

CONCLUSIONS

This cohort study demonstrated a decreasing trend in the incidence of cystic WMI and reported population-based neurological outcomes with cystic WMI, which is important for health-care planning and parental counseling.

Preterm brain Injury: White matter injury

Despite the advances in neonatal intensive care, the preterm brain remains vulnerable to white matter injury (WMI) and disruption of normal brain development (i.e., dysmaturation). Compared to severe cystic WMI encountered in the past decades, contemporary cohorts of preterm neonates experience milder WMIs. More than destructive lesions, disruption of the normal developmental trajectory of cellular elements of the white and the gray matter occurs. In the acute phase, in response to hypoxia-ischemia and/or infection and inflammation, multifocal areas of necrosis within the periventricular white matter involve all cellular elements. Later, chronic WMI is characterized by diffuse WMI with aberrant regeneration of oligodendrocytes, which fail to mature to myelinating oligodendrocytes, leading to myelination disturbances. Complete neuronal degeneration classically accompanies necrotic white matter lesions, while altered neurogenesis, represented by a reduction of the dendritic arbor and synapse formation, is observed in response to diffuse WMI. Neuroimaging studies now provide more insight in assessing both injury and dysmaturation of both gray and white matter. Preterm brain injury remains an important cause of neurodevelopmental disabilities, which are still observed in up to 50% of the preterm survivors and take the form of a complex combination of motor, cognitive, and behavioral concerns.

NIRS improves hemodynamic monitoring and detection of risk for cerebral injury: cases in the neonatal intensive care nursery

Near-infrared spectroscopy (NIRS) monitoring provides a noninvasive, bedside measure of cerebral and somatic oxygenation in neonates at risk for hemodynamic instability and brain injury. This technology has been increasingly utilized in the neonatal intensive care unit, however, clinicians perceive a lack of evidence for the added value of NIRS monitoring. We present six clinical scenarios illustrating the value of NIRS monitoring for the diagnosis and management of critically ill newborns.

Big Data in Neonatal Health Care: Big Reach, Big Reward?

Analog-to-digital data conversion has created massive amounts of historical and real-time health care data. Costs associated with neonatal health issues are high. Big data use in the neonatal intensive care unit has the potential to facilitate earlier detection of clinical deterioration, expedite application of efficient clinical decision-making algorithms based on real-time and historical data mining, and yield significant cost-savings.

Delivery of sevoflurane using a neonatal ventilator

BACKGROUND

Most anesthetic ventilators are designed to cope with a wide range of patient sizes and may lack precision at the lowest end of the minute volume scale. Neonatal intensive care ventilators on the other hand are designed specifically for this patient group, but are not able to deliver volatile anesthesia.

AIMS

We aimed to adapt the neonatal ventilator currently in use in our institution to deliver sevoflurane by incorporating a vaporizer and a scavenging system.

METHODS

We used a Diamedica draw-over vaporizer incorporated into the ventilator circuit and a custom designed open interface scavenging system. A number of safety measures are described to ensure that this equipment is correctly inserted into the circuit.

RESULTS

Bench testing revealed that the vaporizer output is linear and stable within the circuit flow range 4-8 L/min in all modes except high frequency oscillation where concentrations are not predictable. The scavenging system was found to be effective and did not affect volumes, pressures or waveforms when ventilating a test lung over a wide range of flows and pressures. This remained the case over the full range of scavenger flow adjustment.

CONCLUSION

The addition of a Diamedica vaporizer to a Fabian neonatal ventilator was shown in bench testing to provide stable, linear vapor concentrations without compromise of ventilator function. The system should not be used in high frequency oscillation mode because concentrations will exceed those expected and will not maintain a linear relationship with the vaporizer setting.

Monitoring cerebral oxygenation of the immature brain: a neuroprotective strategy?

Monitoring of cerebral oxygenation (rScO₂) with near-infrared spectroscopy (NIRS) is a feasible noninvasive bedside technique in the NICU. This review discusses the possible neuroprotective role of "pattern recognition" of NIRS-derived rScO₂ in preterm neonates with regard to the prevention of severe intraventricular hemorrhage and hypoxia/hyperoxia-related white matter injury. This neuroprotective role of rScO₂ monitoring is discussed as a modality to aid in the early detection of cerebral oxygenation conditions predisposing to these complications. Practical guidelines are provided concerning management of abnormal rScO₂ patterns as well as a brief discussion concerning the need for international consensus and the legal aspects associated with the introduction of a new NICU bedside monitoring strategy.

Multiple Postnatal Infections in Newborns Born Preterm Predict Delayed Maturation of Motor Pathways at Term-Equivalent Age with Poorer Motor Outcomes at 3 Years

OBJECTIVES

To evaluate whether the number of postnatal infections is associated with abnormal white matter maturation and poorer motor neurodevelopmental outcomes at 36 months of corrected age.

STUDY DESIGN

A prospective longitudinal cohort study was undertaken of 219 newborns born preterm at 24-32 weeks of gestational age recruited between 2006 and 2013 with magnetic resonance imaging of the brain both early in life and at term-equivalent age. Postnatal infection was defined as any clinical infection or positive culture ≥72 hours after birth. White matter maturation was assessed by magnetic resonance spectroscopic imaging, magnetic resonance diffusion tensor imaging, and tract-based spatial statistics. Neurodevelopmental outcomes were assessed in 175 (82% of survivors) infants with Bayley Scales of Infant and Toddler Development-III composite scores and Peabody Developmental Motor Scales at 35 months of corrected age (IQR 34-37 months). Infection groups were compared via the Fisher exact test, Kruskal-Wallis test, and generalized estimating equations.

RESULTS

Of 219 neonates born preterm (median gestational age 27.9 weeks), 109 (50%) had no postnatal infection, 83 (38%) had 1 or 2 infections, and 27 (12%) had ≥3 infections. Infants with postnatal infections had more cerebellar hemorrhage. Infants with ≥3 infections had lower N-acetylaspartate/choline in the white matter and basal ganglia regions, lower fractional anisotropy in the posterior limb of the internal capsule, and poorer maturation of the corpus callosum, optic radiations, and posterior limb of the internal capsule on tract-based spatial statistics analysis as well as poorer Bayley Scales of Infant and Toddler Development-III (P = .02) and Peabody Developmental Motor Scales, Second Edition, motor scores (P < .01).

CONCLUSIONS

In newborns born preterm, ≥3 postnatal infections predict impaired development of the motor pathways and poorer motor outcomes in early childhood.

Neurodevelopmental and Behavioral Outcomes in Extremely Premature Neonates With Ventriculomegaly in the Absence of Periventricular-Intraventricular Hemorrhage

IMPORTANCE

Studies of cranial ultrasonography and early childhood outcomes among cohorts of extremely preterm neonates have linked periventricular-intraventricular hemorrhage and cystic periventricular leukomalacia with adverse neurodevelopmental outcomes. However, the association between nonhemorrhagic ventriculomegaly and neurodevelopmental and behavioral outcomes is not fully understood.

OBJECTIVE

To characterize the outcomes of extremely preterm neonates younger than 27 weeks' gestational age who experienced nonhemorrhagic ventriculomegaly that was detected prior to 36 weeks' postmenstrual age.

DESIGN, SETTING, AND PARTICIPANTS

This longitudinal observational study was conducted at 16 centers of the Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network. Infants born prior to 27 weeks' gestational age in any network facility between July 1, 2006, and June 30, 2011, were included if they had a cranial ultrasonogram performed prior to 36 weeks' postmenstrual age. Comparisons were made between those with ventriculomegaly and those with normal cranial sonograms. Data analysis was completed from August 2013 to August 2017.

MAIN OUTCOMES AND MEASURES

The main outcome was neurodevelopmental impairment, defined as a Bayley Scales of Infant and Toddler Development III cognitive score less than 70, moderate/severe cerebral palsy, a Gross Motor Function Classification System score of level 2 or more, vision impairment, or hearing impairment. Secondary outcomes included Bayley Scales of Infant and Toddler Development III subscores, components of neurodevelopmental impairment, behavioral outcomes, and death/neurodevelopmental impairment. Logistic regression was used to evaluate the association of ventriculomegaly with adverse outcomes while controlling for potentially confounding variables and center differences as a random effect. Linear regression was used similarly for continuous outcomes.

RESULTS

Of 4193 neonates with ultrasonography data, 300 had nonhemorrhagic ventriculomegaly (7%); 3045 had normal cranial ultrasonograms (73%), 775 had periventricular-intraventricular hemorrhage (18.5%), and 73 had cystic periventricular leukomalacia (1.7%). Outcomes were available for 3008 of 3345 neonates with ventriculomegaly or normal scans (90%). Compared with normal cranial ultrasonograms, ventriculomegaly was associated with lower gestational age, male sex, and bronchopulmonary dysplasia, late-onset sepsis, meningitis, necrotizing enterocolitis, and stage 3 retinopathy of prematurity. After adjustment, neonates with ventriculomegaly had higher odds of neurodevelopmental impairment (odds ratio [OR], 3.07; 95% CI, 2.13-4.43), cognitive impairment (OR, 3.23; 95% CI, 2.09-4.99), moderate/severe cerebral palsy (OR, 3.68; 95% CI, 2.08-6.51), death/neurodevelopmental impairment (OR, 2.17; 95% CI, 1.62-2.91), but not death alone (OR, 1.09; 95% CI, 0.76-1.57). Behavioral outcomes did not differ.

CONCLUSIONS AND RELEVANCE

Nonhemorrhagic ventriculomegaly is associated with increased odds of neurodevelopmental impairment among extremely preterm neonates.

Origin and dynamics of oligodendrocytes in the developing brain: Implications for perinatal white matter injury

Infants born prematurely are at high risk to develop white matter injury (WMI), due to exposure to hypoxic and/or inflammatory insults. Such perinatal insults negatively impact the maturation of oligodendrocytes (OLs), thereby causing deficits in myelination. To elucidate the precise pathophysiology underlying perinatal WMI, it is essential to fully understand the cellular mechanisms contributing to healthy/normal white matter development. OLs are responsible for myelination of axons. During brain development, OLs are generally derived from neuroepithelial zones, where neural stem cells committed to the OL lineage differentiate into OL precursor cells (OPCs). OPCs, in turn, develop into premyelinating OLs and finally mature into myelinating OLs. Recent studies revealed that OPCs develop in multiple waves and form potentially heterogeneous populations. Furthermore, it has been shown that myelination is a dynamic and plastic process with an excess of OPCs being generated and then abolished if not integrated into neural circuits. Myelination patterns between rodents and humans show high spatial and temporal similarity. Therefore, experimental studies on OL biology may provide novel insights into the pathophysiology of WMI in the preterm infant and offers new perspectives on potential treatments for these patients.

Combined fetal inflammation and postnatal hypoxia causes myelin deficits and autism-like behavior in a rat model of diffuse white matter injury

Diffuse white matter injury (WMI) is a serious problem in extremely preterm infants, and is associated with adverse neurodevelopmental outcome, including cognitive impairments and an increased risk of autism-spectrum disorders. Important risk factors include fetal or perinatal inflammatory insults and fluctuating cerebral oxygenation. However, the exact mechanisms underlying diffuse WMI are not fully understood and no treatment options are currently available. The use of clinically relevant animal models is crucial to advance knowledge on the pathophysiology of diffuse WMI, allowing the definition of novel therapeutic targets. In the present study, we developed a multiple-hit animal model of diffuse WMI by combining fetal inflammation and postnatal hypoxia in rats. We characterized the effects on white matter development and functional outcome by immunohistochemistry, MRI and behavioral paradigms. Combined fetal inflammation and postnatal hypoxia resulted in delayed cortical myelination, microglia activation and astrogliosis at P18, together with long-term changes in oligodendrocyte maturation as observed in 10 week old animals. Furthermore, rats with WMI showed impaired motor performance, increased anxiety and signs of autism-like behavior, i.e. reduced social play behavior and increased repetitive grooming. In conclusion, the combination of fetal inflammation and postnatal hypoxia in rats induces a pattern of brain injury and functional impairments that closely resembles the clinical situation of diffuse WMI. This animal model provides the opportunity to elucidate pathophysiological mechanisms underlying WMI, and can be used to develop novel treatment options for diffuse WMI in preterm infants.

Relationship between PCO2 and unfavorable outcome in infants with moderate-to-severe hypoxic ischemic encephalopathy

BACKGROUND

Abnormal PCO2 is common in infants with hypoxic ischemic encephalopathy (HIE). The objective was to determine whether hypocapnia was independently associated with unfavorable outcome (death or severe neurodevelopmental disability at 18 mo) in infants with moderate-to-severe HIE.

METHODS

This was a post hoc analysis of the CoolCap Study in which infants were randomized to head cooling or standard care. Blood gases were measured at prespecified times after randomization. PCO2 and follow-up data were available for 196 of 234 infants. Analyses were performed to investigate the relationship between hypocapnia in the first 72 h after randomization and unfavorable outcome.

RESULTS

After adjusting for pH, amplitude-integrated electroencephalogram background and seizures, birth weight, Apgar score at 5 min, cooling status, and Sarnat stage, PCO2 was inversely associated with unfavorable outcome (P < 0.001). The probability of unfavorable outcome was 0.20 ± 0.1 (point estimate ± SE), 0.53 ± 0.23 and 0.89 ± 0.16 for a PCO2 of 40, 30, and 20 mm Hg respectively and was greater in infants with severe HIE than with moderate HIE.

CONCLUSIONS

Hypocapnia in infants with moderate-to-severe HIE was independently associated with unfavorable outcome. Future studies of controlled normocapnia will be important.

White Matter Injury in Premature Newborns

Preterm newborns are highly susceptible to brain injury. White matter injury is among the dominant patterns of brain injury in preterm newborns. the purpose of this review is to discuss the pathogenesis, diagnosis, management, and prevention of white matter injury in premature newborns. the long-term outcome of white matter injury in children born prematurely is also addressed.

Volume-targeted versus pressure-limited ventilation in infants born at or near term

Our aims were to determine whether volume-targeted ventilation (VTV) or pressure-limited ventilation (PLV) reduced the time to successful extubation and if any difference was explained by a lower work of breathing (WOB), better respiratory muscle strength or less thoracoabdominal asynchrony (TAA) and associated with fewer hypocarbic episodes. Infants born at ≥34 weeks of gestational age were randomised to VTV or PLV. The WOB was assessed by the transdiaphragmatic pressure time product, respiratory muscle strength by the maximum inflation (Pimax) and expiratory (Pemax) pressures and TAA assessed using uncalibrated respiratory inductance plethysmography. Forty infants, median gestational age of 39 (range 34-42) weeks, were recruited. The time to successful extubation did not differ between the two groups (median 25, range 2.5-312 h (VTV) versus 33.5, 1.312 h (PLV)) (p = 0.461). There were no significant differences between the groups with regard to the WOB, respiratory muscle strength or the TAA results. The median number of hypocarbic episodes was 1.5 (range 0-8) in the VTV group versus 4 (range 1-13) in the PLV group (p = 0.005).

CONCLUSION

In infants born at or near term, VTV compared to PLV did not reduce the time to successful extubation but was associated with significantly fewer hypocarbic episodes.

WHAT IS KNOWN

In prematurely born infants, volume-targeted ventilation (VTV) compared to pressure-limited ventilation (PLV) reduces bronchopulmonary dysplasia or death. In addition, VTV is associated in prematurely born infants with lower incidences of pneumothorax, intraventricular haemorrhage and hypocarbic episodes.

WHAT IS NEW

Despite a high morbidity, few studies have investigated optimum ventilation strategies for infants born at or near term. In a RCT, we have demonstrated VTV versus PLV in infants ≥34 weeks gestation was associated with significantly fewer hypocarbic episodes.

Impaired oligodendrocyte maturation in preterm infants: Potential therapeutic targets

Preterm birth is an evolving challenge in neonatal health care. Despite declining mortality rates among extremely premature neonates, morbidity rates remain very high. Currently, perinatal diffuse white matter injury (WMI) is the most commonly observed type of brain injury in preterm infants and has become an important research area. Diffuse WMI is associated with impaired cognitive, sensory and psychological functioning and is increasingly being recognized as a risk factor for autism-spectrum disorders, ADHD, and other psychological disturbances. No treatment options are currently available for diffuse WMI and the underlying pathophysiological mechanisms are far from being completely understood. Preterm birth is associated with maternal inflammation, perinatal infections and disrupted oxygen supply which can affect the cerebral microenvironment by causing activation of microglia, astrogliosis, excitotoxicity, and oxidative stress. This intricate interplay of events negatively influences oligodendrocyte development, causing arrested oligodendrocyte maturation or oligodendrocyte cell death, which ultimately results in myelination failure in the developing white matter. This review discusses the current state in perinatal WMI research, ranging from a clinical perspective to basic molecular pathophysiology. The complex regulation of oligodendrocyte development in healthy and pathological conditions is described, with a specific focus on signaling cascades that may play a role in WMI. Furthermore, emerging concepts in the field of WMI and issues regarding currently available animal models are put forward. Novel insights into the molecular mechanisms underlying impeded oligodendrocyte maturation in diffuse WMI may aid the development of novel treatment options which are desperately needed to improve the quality-of-life of preterm neonates.

Umbilical Arterial Blood Sampling Alters Cerebral Tissue Oxygenation in Very Low Birth Weight Neonates

OBJECTIVE

To evaluate the magnitude, consistency, and natural history of reductions in cerebral regional tissue oxygenation (CrSO2) during umbilical arterial (UA) blood sampling in very low birth weight neonates.

STUDY DESIGN

Data were collected during a prospective observational near-infrared spectroscopy survey conducted on a convenience sample of 500-1250 g neonates during the first 10 postnatal days. A before-after analysis of UA blood sampling effects on CrSO2 absolute values and variability was performed. The present analysis was not designed a priori and was conducted following the bedside observation of CrSO2 decrements contiguous with UA blood draws.

RESULTS

Fifteen very low birth weight neonates had 201 UA blood draws. Baseline CrSO2 (mean ± SEM) decreased following UA blood sampling, from 70 ± 1% to a nadir of 63 ± 1% (P < .001) occurring 4 ± 3 (range 2-24) minutes following blood draws. CrSO2 subsequently increased to 70 ± 1% (P < .001 compared with nadir) at 10 ± 4 (range 4-28) minutes following UA blood sampling. Coefficients of variation (mean ± SEM) increased from 0.02 ± 0.001 at baseline to 0.05 ± 0.004 (P < .001), followed by a decrease to 0.03 ± 0.003 (P < .001 for all comparisons), thus denoting increased CrSO2 variability following UA blood sampling.

CONCLUSIONS

UA blood sampling is associated with significant CrSO2 decrements with increased variability over clinically significant intervals. Whether these changes impact complications of prematurity, including intraventricular hemorrhage and periventricular leukomalacia, remain unknown.

The effect of resuscitation in 100% oxygen on brain injury in a newborn rat model of severe hypoxic-ischaemic encephalopathy

AIM

Infants with birth asphyxia frequently require resuscitation. Current guidance is to start newborn resuscitation in 21% oxygen. However, infants with severe hypoxia-ischaemia may require prolonged resuscitation with oxygen. To date, no study has looked at the effect of resuscitation in 100% oxygen following a severe hypoxic-ischaemic insult.

METHODS

Postnatal day 7 Wistar rats underwent a severe hypoxic-ischaemic insult (modified Vannucci unilateral brain injury model) followed by immediate resuscitation in either 21% or 100% oxygen for 30 min. Seven days following the insult, negative geotaxis testing was performed in survivors, and the brains were harvested. Relative ipsilateral cortical and hippocampal area loss was assessed histologically.

RESULTS

Total area loss in the affected hemisphere and area loss within the hippocampus did not significantly differ between the two groups. The same results were seen for short-term neurological assessment. No difference was seen in weight gain between pups resuscitated in 21% and 100% oxygen.

CONCLUSION

Resuscitation in 100% oxygen does not cause a deleterious effect on brain injury following a severe hypoxic-ischaemic insult in a rat model of hypoxia-ischaemia. Further work investigating the effects of resuscitation in 100% oxygen is warranted, especially for newborn infants with severe hypoxic-ischaemic encephalopathy.

Screening Cranial Imaging at Multiple Time Points Improves Cystic Periventricular Leukomalacia Detection

OBJECTIVE

The aim of this study is to determine whether the cystic periventricular leukomalacia (cPVL) detection rate differs between imaging studies performed at different time points.

DESIGN

We retrospectively reviewed the prospectively collected data of 31,708 infants from the NICHD Neonatal Research Network. Inclusion criteria were infants < 1,000 g birth weight or < 29 weeks' gestational age who had cranial imaging performed using both early criterion (cranial ultrasound [CUS] < 28 days chronological age) and late criterion (CUS, magnetic resonance imaging, or computed tomography closest to 36 weeks postmenstrual age [PMA]). We compared the frequency of cPVL diagnosed by early and late criteria.

RESULTS

About 664 (5.2%) of the 12,739 infants who met inclusion criteria had cPVL using either early or late criteria; 569 using the late criterion, 250 using the early criterion, and 155 patients at both times. About 95 (14.3%) of 664 cPVL cases seen on early imaging were no longer visible on repeat screening closest to 36 weeks PMA. Such disappearance of cPVL was more common in infants < 26 weeks' gestation versus infants of 26 to 28 weeks' gestation (18.5 vs. 11.5%; p = 0.013).

CONCLUSIONS

Cranial imaging at both < 28 days chronological age and closest to 36 weeks PMA improves cPVL detection, especially for more premature infants.

PaCO2 in surfactant, positive pressure, and oxygenation randomised trial (SUPPORT)

OBJECTIVE

To determine the association of arterial partial pressure of carbon dioxide PaCO2 with severe intraventricular haemorrhage (sIVH), bronchopulmonary dysplasia (BPD), and neurodevelopmental impairment (NDI) at 18-22 months in premature infants.

DESIGN

Secondary exploratory data analysis of Surfactant, Positive Pressure, and Oxygenation Randomised Trial (SUPPORT).

SETTING

Multiple referral neonatal intensive care units.

PATIENTS

1316 infants 24 0/7 to 27 6/7 weeks gestation randomised to different oxygenation (SpO2 target 85-89% vs 91-95%) and ventilation strategies.

MAIN OUTCOME MEASURES

Blood gases from postnatal day 0 to day14 were analysed. Five PaCO2 variables were defined: minimum (Min), maximum (Max), SD, average (time-weighted), and a four level categorical variable (hypercapnic (highest quartile of Max PaCO2), hypocapnic (lowest quartile of Min PaCO2), fluctuators (hypercapnia and hypocapnia), and normocapnic (middle two quartiles of Max and Min PaCO2)). PaCO2 variables were compared for infants with and without sIVH, BPD and NDI (±death). Multivariable logistic regression models were developed for adjusted results.

RESULTS

sIVH, BPD and NDI (±death) were associated with hypercapnic infants and fluctuators. Association of Max PaCO2 and outcomes persisted after adjustment (per 10 mm Hg increase: sIVH/death: OR 1.27 (1.13 to 1.41); BPD/death: OR 1.27 (1.12 to 1.44); NDI/death: OR 1.23 (1.10 to 1.38), death: OR 1.27 (1.12 to 1.44), all p<0.001). No interaction was found between PaCO2 category and SpO2 treatment group for sIVH/death, NDI/death or death. Max PaCO2 was positively correlated with maximum FiO2 (rs0.55, p<0.0001) and ventilator days (rs0.61, p<0.0001).

CONCLUSIONS

Higher PaCO2 was an independent predictor of sIVH/death, BPD/death and NDI/death. Further trials are needed to evaluate optimal PaCO2 targets for high-risk infants.

Clinical Use of Nonconventional Modes of Ventilator Support

High-frequency oscillatory ventilation (HFOV) is now a mainstay of respiratory care for the neonatal patient. In this chapter, we will define HFOV as those ventilators with a “true” active expiratory phase created by a piston or diaphragm. Jet ventilation and flow interrupters are discussed elsewhere in this book.

Cerebral vascular regulation and brain injury in preterm infants

Cerebrovascular lesions, mainly germinal matrix hemorrhage and ischemic injury to the periventricular white matter, are major causes of adverse neurodevelopmental outcome in preterm infants. Cerebrovascular lesions and neuromorbidity increase with decreasing gestational age, with the white matter predominantly affected. Developmental immaturity in the cerebral circulation, including ongoing angiogenesis and vasoregulatory immaturity, plays a major role in the severity and pattern of preterm brain injury. Prevention of this injury requires insight into pathogenesis. Cerebral blood flow (CBF) is low in the preterm white matter, which also has blunted vasoreactivity compared with other brain regions. Vasoreactivity in the preterm brain to cerebral perfusion pressure, oxygen, carbon dioxide, and neuronal metabolism is also immature. This could be related to immaturity of both the vasculature and vasoactive signaling. Other pathologies arising from preterm birth and the neonatal intensive care environment itself may contribute to impaired vasoreactivity and ineffective CBF regulation, resulting in the marked variations in cerebral hemodynamics reported both within and between infants depending on their clinical condition. Many gaps exist in our understanding of how neonatal treatment procedures and medications have an impact on cerebral hemodynamics and preterm brain injury. Future research directions for neuroprotective strategies include establishing cotside, real-time clinical reference values for cerebral hemodynamics and vasoregulatory capacity and to demonstrate that these thresholds improve long-term outcomes for the preterm infant. In addition, stimulation of vascular development and repair with growth factor and cell-based therapies also hold promise.

Neuroimaging of white matter injury, intraventricular and cerebellar hemorrhage

White matter injury and hemorrhage are common findings in extremely preterm infants. Large hemorrhages and extensive cystic lesions are identified with cranial ultrasound. MRI, which is more sensitive, is especially useful in the identification of small intraventricular hemorrhage; cerebellar hemorrhage; punctate lesion in the white matter and cerebellum; and diffuse, noncystic white matter injury. Imaging sequences such as diffusion-weighted, diffusion tensor, and susceptibility weighted imaging may improve recognition and prediction of outcome. These techniques improve understanding of the underlying pathophysiology of white matter injury and its effects on brain development and neurodevelopmental outcome.

Focal necrosis and disturbed myelination in the white matter of newborn infants: a tale of too much or too little oxygen

White matter disease in preterm infants comes along with focal destructions or with diffuse myelination disturbance. Recent experimental work with transgenic mice paves the way for a unifying molecular model for both types of brain injury, placing oxygen sensing by oligodendrocyte precursor cells (OPCs) at the center stage. Mice genetically altered to mimic high local oxygen tension in oligodendroglia lineage cells (via deletion of hypoxia-inducible factor, HIF) develop white matter disease resembling cystic periventricular leukomalacia within the first 7 days of life. Mice in which local hypoxia is mimicked in oligodendroglial cells (via genetic inhibition of HIF decay) display arrested OPC maturation and subsequent hypomyelination, reminiscent of the diffuse white matter disease observed in preterm infants and infants with congenital heart disease. These recent experimental findings on oxygen sensing and myelination are awaiting integration into a clinical framework. Gene regulation in response to hyperoxia or hypoxia, rather than oxidative stress, may be an important mechanism underlying neonatal white matter disease.

Limitations and vulnerabilities of the neonatal cardiovascular system: considerations for anesthetic management

Development of the cardiovascular system through the last trimester of pregnancy and the subsequent neonatal period is profound. Morphological changes within the myocardium make the heart vulnerable to challenges such as fluid shifts and anesthetic drugs. The sensitivity of the myocardium to metabolic challenges and potential harm of drugs needed to maintain adequate blood pressure and cardiac output are highlighted. Traditional monitoring under anesthesia has focussed on maintaining oxygenation and heart rate in the neonate with less attention paid to blood pressure, cardiac output, and more importantly organ well-being. There is now a better understanding of the limitations of blood pressure homeostasis in the neonate and the potential consequences of marginal hypoperfusion. This article highlights some of these vulnerabilities particularly as they relate to anesthesia and surgery in the very young.

Diffusion magnetic resonance imaging in preterm brain injury

INTRODUCTION

White matter injury and abnormal maturation are thought to be major contributors to the neurodevelopmental disabilities observed in children and adolescents who were born preterm. Early detection of abnormal white matter maturation is important in the design of preventive, protective, and rehabilitative strategies for the management of the preterm infant. Diffusion-weighted magnetic resonance imaging (d-MRI) has become a valuable tool in assessing white matter maturation and injury in survivors of preterm birth. In this review, we aim to (1) describe the basic concepts of d-MRI; (2) evaluate the methods that are currently used to analyse d-MRI; (3) discuss neuroimaging correlates of preterm brain injury observed at term corrected age; during infancy, adolescence and in early adulthood; and (4) explore the relationship between d-MRI measures and subsequent neurodevelopmental performance.

METHODS

References for this review were identified through searches of PubMed and Google Scholar before March 2013.

RESULTS

The impact of premature birth on cerebral white matter can be observed from term-equivalent age through to adulthood. Disruptions to white matter development, identified by d-MRI, are related to diminished performance in functional domains including motor performance, cognition and behaviour in early childhood and in later life.

CONCLUSION

d-MRI is an effective tool for investigating preterm white matter injury. With advances in image acquisition and analysis approaches, d-MRI has the potential to be a biomarker of subsequent outcome and to evaluate efficacy of clinical interventions in this population.

Sidestream microstream end tidal carbon dioxide measurements and blood gas correlations in neonatal intensive care unit

OBJECTIVE

The study was designed to assess the use of newer sidestream microstream end tidal carbon dioxide (ETCO(2) ) device in predicting blood carbon dioxide (PCO(2) ) measurements in very low birth weight (VLBW = birth weight <1,500 g) and non-VLBW NICU neonates.

STUDY DESIGN

Sidestream microstream ETCO(2) detectors were allowed time to calibrate and reach steady state prior to blood gas measurements. Blood CO(2) (PCO(2) ) and simultaneous ETCO(2) were recorded. Ratio of dead space to tidal volume (VD/VT) was calculated using modified Bohr's equation. Correlation coefficient, estimates of difference, standard deviation, and 95% limits of agreement between ETCO(2) and PCO(2) concentrations were calculated.

RESULTS

Two hundred eighty-six paired samples were collected from 48 ventilated NICU patients. Average PCO(2) and ETCO(2) were 58.4 and 50.6 with a correlation of 0.76. Subgroup analysis showed a correlation of 0.73 in 204 paired blood from 34 VLBW infants and 0.82 in 82 paired samples from non-VLBW infants. Estimates of difference ± standard deviation between PCO(2) and ETCO(2) concentrations in these three groups, respectively (ALL, VLBW, and non-VLBW) were 7.84 ± 9.96, 8.2 ± 10.16, and 6.95 ± 9.45. The correlation coefficient significantly improved in the VLBW group to 0.86 with dead space to tidal volume ratio (VD/VT) <30% (0.86 vs. 0.42; P < 0.001).

CONCLUSION

ETCO(2) measurements using sidestream microstream technology in VLBW demonstrated that the correlation of ETCO(2) and PCO(2) was moderate, but the agreement was less than adequate (bias > 5 mmHg in all groups). The results improved with lower VD/VT, suggesting that sidestream capnography is more reliable in conditions of less severe lung disease.

Incidence of brain injuries in premature infants with gestational age ≤ 34 weeks in ten urban hospitals in China

BACKGROUND

There is a large number (1.5 million per year) of premature births in China. It is necessary to obtain the authentic incidences of intraventricular hemorrhage (IVH) and periventricular leukomalacia (PVL), the common brain injuries, in Chinese premature infants. The present multicenter study aimed to investigate the incidence of brain injuries in premature infants in ten urban hospitals in China.

METHODS

The research proposal was designed by the Subspecialty Group of Neonatology of Pediatric Society of the Chinese Medical Association. Ten large-scale urban hospitals voluntarily joined the multicenter investigation. All premature infants with a gestational age ≤ 34 weeks in the ten hospitals were subjected to routine cranial ultrasound within three days after birth, and then to repeated ultrasound every 3-7 days till their discharge from the hospital from January 2005 to August 2006. A uniform data collection sheet was designed to record cases of brain injuries.

RESULTS

The incidences of overall IVH and severe IVH were 19.7% (305/1551) and 4.6% (72/1551), respectively with 18.4% (56/305) for grade 1, 58.0% (177/305) for grade 2, 17.7% (54/305) for grade 3 and 5.9% (18/305) for grade 4 in nine hospitals. The incidences of overall PVL and cystic PVL were 5.0% (89/1792) and 0.8% (14/1792) respectively, with 84.3% (75/89) for grade 1, 13.5% (12/89) for grade 2, and 2.2% (2/89) for grade 3 in the ten hospitals. The statistically significant risk factors that might aggravate the severity of IVH were vaginal delivery (OR=1.883, 95% CI: 1.099-3.228, P=0.020) and mechanical ventilation (OR=4.150, 95% CI: 2.384-7.223, P=0.000). The risk factors that might result in the development of cystic PVL was vaginal delivery (OR=21.094, 95% CI: 2.650-167.895, P=0.000).

CONCLUSIONS

The investigative report can basically reflect the incidence of brain injuries in premature infants in major big cities of China. Since more than 60% of the Chinese population live in the rural areas of China, it is expected to undertake a further multicenter investigation covering the rural areas in the future.

Randomised trial of volume-targeted ventilation versus pressure-limited ventilation in acute respiratory failure in prematurely born infants

BACKGROUND

During volume-targeted ventilation (VTV), a constant volume is delivered with each ventilator inflation.

OBJECTIVES

To determine whether VTV compared to pressure-limited ventilation (PLV) reduced the time to reach weaning criteria in prematurely born infants with acute respiratory distress, and if any difference was explained by better respiratory muscle strength and/or a lower work of breathing (WOB).

METHODS

Infants of <34 weeks of gestational age ventilated for <24 h in the first week after birth were randomised to receive either VTV or PLV. The primary outcome was the time to achieve pre-specified weaning criteria. Respiratory muscle strength was assessed by the measurement of the maximum inflation and expiratory pressures, and the WOB assessed by the transdiaphragmatic pressure time product. Other outcomes reported are the duration of ventilation, occurrence of patent ductus arteriosus, pneumothorax, intraventricular haemorrhage, periventricular leukomalacia and episodes of hypocarbia.

RESULTS

Forty infants, median gestational age 27 (range 23-33) weeks, were recruited. The time taken to achieve weaning criteria was similar in the two groups [median 14 h (VTV) vs. 23 h (PLV)]. There were no significant differences between the groups with regard to respiratory muscle strength, WOB or other outcomes, except that fewer of the VTV compared to the PLV group had episodes of hypocarbia (8 vs. 19; p < 0.001).

CONCLUSION

In prematurely born infants with acute respiratory failure, use of VTV did not reduce the time to reach weaning criteria, but was associated with a reduction in episodes of hypocarbia.

Increased inspired oxygen in the first hours of life is associated with adverse outcome in newborns treated for perinatal asphyxia with therapeutic hypothermia

OBJECTIVE

To assess whether increased inspired oxygen and/or hypocarbia during the first 6 hours of life are associated with adverse outcome at 18 months in term neonates treated with therapeutic hypothermia.

STUDY DESIGN

Blood gas values and ventilatory settings were monitored hourly in 61 newborns for 6 hours after birth. We investigated if there was an association between increased inspired oxygen and/or hypocarbia and adverse outcome (death or disability by Bayley Scales of Newborn Development II examination at 18-20 months).

RESULTS

Hypothermia was started from 3 hours 45 minutes (10 minutes-10 hours) and median lowest Pco(2) level within the first 6 hours of life was 30 mm Hg (16.5-96 mm Hg). The median highest fraction of inspiratory oxygen within the first hour of life was 0.43 (0.21-1.00). The area under the curve fraction of inspiratory oxygen and Pao(2) for hours 1-6 of life was 0.23 (0.21-1.0) and 86 mm Hg (22-197 mm Hg), respectively. We did not find any association between any measures of hypocapnia and adverse outcome (P > .05), but increased inspired oxygen correlated with adverse outcome, even when excluding newborns with initial oxygenation failure (P < .05).

CONCLUSION

Increased fraction of inspired oxygen within the first 6 hours of life was significantly associated with adverse outcome in newborns treated with therapeutic hypothermia following hypoxic ischemic encephalopathy.

Ductal ligation in the very low-birth weight infant: simple anesthesia or extreme art?

Management of the very low-birth weight infant in the neonatal intensive care unit (NICU) is geared to provide optimal outcome not only in term of survival but increasingly with a goal of limitation of long-term neurological and pulmonary morbidities. Careful follow-up studies have demonstrated that relatively small variations in oxygenation and gas exchange, ventilator management, and other management modalities can have long-term consequences. Within this context, there are good data that closure of a clinically significant patent ductus arteriosus has outcome benefit, but little data on the idealized anesthetic to manage such fragile patients. Does the anesthetic management matter? Given the attention to detail within the NICU, it would seem prudent to try to choose techniques that limit changes in hemodynamics, gas exchange, and ventilation within the context of the surgery. Anesthesia for ductal ligation in the very low-birth weight infant may need to be judged by more than simple survival and brings into question the current techniques and monitoring used.

Blood protein concentrations in the first two postnatal weeks associated with early postnatal blood gas derangements among infants born before the 28th week of gestation. The ELGAN Study

AIM

To explore the relationships between blood gas derangements and blood concentrations of inflammation-related proteins shortly after preterm birth.

DESIGN

Observational cohort.

SETTING

Fourteen neonatal intensive care units.

SUBJECTS

Seven hundred and forty five infants born before the 28th week of gestation who were classified by their blood gas derangements during the first three postnatal days and by the concentrations of 25 proteins in their blood on days 1, 7, and 14. We classified these newborns by whether or not they had a highest or lowest PaO2, PCO2, and lowest pH in the most extreme quartile, and by whether or not they had a protein concentration in the highest quartile.

RESULTS

Blood gas derangements on two days were much more likely to be accompanied or followed by sustained or recurrent systemic inflammation than a derangement on only one day. This was most evident for acidemia, and slightly less so for hypercapnia.

CONCLUSIONS

Our finding that protein concentration patterns indicative of systemic inflammation are associated with several blood gas derangements raises the possibility that organ damage attributed to these derangements might be accompanied by or involve an inflammatory response.

Reprint of "The developing oligodendrocyte: key cellular target in brain injury in the premature infant"

Brain injury in the premature infant, a problem of enormous importance, is associated with a high risk of neurodevelopmental disability. The major type of injury involves cerebral white matter and the principal cellular target is the developing oligodendrocyte. The specific phase of the oligodendroglial lineage affected has been defined from study of both human brain and experimental models. This premyelinating cell (pre-OL) is vulnerable because of a series of maturation-dependent events. The pathogenesis of pre-OL injury relates to operation of two upstream mechanisms, hypoxia-ischemia and systemic infection/inflammation, both of which are common occurrences in premature infants. The focus of this review and of our research over the past 15-20 years has been the cellular and molecular bases for the maturation-dependent vulnerability of the pre-OL to the action of the two upstream mechanisms. Three downstream mechanisms have been identified, i.e., microglial activation, excitotoxicity and free radical attack. The work in both experimental models and human brain has identified a remarkable confluence of maturation-dependent factors that render the pre-OL so exquisitely vulnerable to these downstream mechanisms. Most importantly, elucidation of these factors has led to delineation of a series of potential therapeutic interventions, which in experimental models show marked protective properties. The critical next step, i.e., clinical trials in the living infant, is now on the horizon.

Decreasing incidence and severity of cerebral palsy in prematurely born children

OBJECTIVE

To examine incidence and severity of cerebral palsy (CP), and associated factors among preterm survivors (gestational age <34 weeks), admitted to a neonatal intensive care unit from 1990-2005.

STUDY DESIGN

Eighteen antenatal, perinatal and postnatal factors were analyzed. The cohort was divided in four birth periods: 1990-1993 (n=661), 1994-1997 (n=726), 1998-2001 (n=723), and 2002-2005 (n=850). The Gross Motor Function Classification System was used as primary outcome measure (mean age: 32.9 ± 5.3 months). Logistic regression analyses were used.

RESULTS

CP incidence decreased from 6.5% in period I, to 2.6%, 2.9% and 2.2% (P<.001) in period II-IV, respectively. Simultaneously, cystic periventricular leukomalacia (c-PVL) decreased from 3.3% in period I to 1.3% in period IV (P=.004). Within the total cohort (n=3287), c-PVL grade III decreased from 2.3% in period I to 0.2% in period IV (P=.003). The number of children with Gross Motor Function Classification System levels III-V decreased from period I to IV (P=.035). Independent risk factors for CP were c-PVL and severe intraventricular hemorrhage, whereas antenatal antibiotics, presence of an arterial line, Caesarean section, and gestational age were independent protective factors.

CONCLUSION

CP incidence and severity decreased from 1990-1993 onward, which could be attributed to a reduction of 93% in severe c-PVL.

Hypocarbia and adverse outcome in neonatal hypoxic-ischemic encephalopathy

OBJECTIVE

To evaluate the association between early hypocarbia and 18- to 22-month outcome among neonates with hypoxic-ischemic encephalopathy.

STUDY DESIGN

Data from the National Institute of Child Health and Human Development Neonatal Research Network randomized, controlled trial of whole-body hypothermia for neonatal hypoxic-ischemic encephalopathy were used for this secondary observational study. Infants (n = 204) had multiple blood gases recorded from birth to 12 hours of study intervention (hypothermia versus intensive care alone). The relationship between hypocarbia and outcome (death/disability at 18 to 22 months) was evaluated by unadjusted and adjusted analyses examining minimum PCO(2) and cumulative exposure to PCO(2) <35 mm Hg. The relationship between cumulative PCO(2) <35 mm Hg (calculated as the difference between 35 mm Hg and the sampled PCO(2) multiplied by the duration of time spent <35 mm Hg) and outcome was evaluated by level of exposure (none-high) using a multiple logistic regression analysis with adjustments for pH, level of encephalopathy, treatment group (± hypothermia), and time to spontaneous respiration and ventilator days; results were expressed as odds ratios and 95% confidence intervals. Alternative models of CO(2) concentration were explored to account for fluctuations in CO(2).

RESULTS

Both minimum PCO(2) and cumulative PCO(2) <35 mm Hg were associated with poor outcome (P < .05). Moreover, death/disability increased with greater cumulative exposure to PCO(2) <35 mm Hg.

CONCLUSIONS

Hypocarbia is associated with poor outcome after hypoxic-ischemic encephalopathy.

The developing oligodendrocyte: key cellular target in brain injury in the premature infant

Brain injury in the premature infant, a problem of enormous importance, is associated with a high risk of neurodevelopmental disability. The major type of injury involves cerebral white matter and the principal cellular target is the developing oligodendrocyte. The specific phase of the oligodendroglial lineage affected has been defined from study of both human brain and experimental models. This premyelinating cell (pre-OL) is vulnerable because of a series of maturation-dependent events. The pathogenesis of pre-OL injury relates to operation of two upstream mechanisms, hypoxia-ischemia and systemic infection/inflammation, both of which are common occurrences in premature infants. The focus of this review and of our research over the past 15-20 years has been the cellular and molecular bases for the maturation-dependent vulnerability of the pre-OL to the action of the two upstream mechanisms. Three downstream mechanisms have been identified, i.e., microglial activation, excitotoxicity and free radical attack. The work in both experimental models and human brain has identified a remarkable confluence of maturation-dependent factors that render the pre-OL so exquisitely vulnerable to these downstream mechanisms. Most importantly, elucidation of these factors has led to delineation of a series of potential therapeutic interventions, which in experimental models show marked protective properties. The critical next step, i.e., clinical trials in the living infant, is now on the horizon.