Unraveling the Links Between the Initiation of Ventilation and Brain Injury in Preterm Infants

T-piece resuscitator versus self-inflating bag for resuscitation in the delivery room in preterm neonates: a randomised controlled trial

OBJECTIVE

To compare the efficacy of T-piece resuscitator (TPR) and self-inflating bag (SIB) for resuscitation of preterm neonates in the delivery room.

SETTINGS

Level III neonatal intensive care unit in North India.

DESIGN

Open-label, parallel-group, randomised controlled trial.

PATIENT

Preterm neonates of>26-34 weeks of gestation requiring positive pressure ventilation (PPV) at birth.

INTERVENTION

Neonates needing PPV at birth were identified using Neonatal Resuscitation Programme guidelines, 2020, and resuscitated using either TPR or SIB as per permuted block random sequence.

MAIN OUTCOME MEASURES

Primary outcome was need for delivery room endotracheal intubation. Secondary outcomes were duration of PPV, oxygen saturation (SpO2) at 2 and 5 min, time to spontaneous respiration and heart rate>100 beats per minute.

RESULTS

Mean gestation age (weeks; 30±2.1 vs 31±2) and birth weight (g; 1400±408 vs 1450±427) were comparable. Of the total 120, 8 (13.7%) in the TPR group versus 19 (30.6%) neonates in the SIB group were intubated in the delivery room (risk difference (95% CI), -0.16 (-0.31 to -0.02); p=0.03). SpO2 mean (SD) at 5 min in TPR group and SIB group were 82.9±8.7% and 78.9±12.1%, respectively; mean difference (95% CI), 3.99 (0.15 to 7.83); p=0.04). Median (IQR) of combined Apgar at 5 min in TPR group and SIB group were 13 (12-14) and 12 (10-13), p 0.02. Other outcomes were comparable.

CONCLUSION

TPR is more efficacious than SIB in terms of lesser delivery room intubation and better SpO2 at 5 min in preterm neonates.

Does Leak Matter? A Novel Dynamic Leak Model to Simulate Leak for Performance Testing of Manual Neonatal Resuscitation Devices. A Bench Study

INTRODUCTION

Newborn resuscitation is commonly performed in the presence of face mask leak. Leak is highly variable, pressure-dependent and often unrecognized. The effectiveness of resuscitation devices to deliver adequate inflations in the presence of leak is unknown. Bench models simulating continuous leak have the disadvantage of not accurately reflecting leak occurring during clinical resuscitation. A dynamic leak model based on pressure-release valves was thus developed.

METHODS

This study investigates self-inflating bag (SIB) and T-piece resuscitator (TPR) ventilation performance in the presence of dynamic (DLM) compared to continuous (CLM) leak models in a bench study. Five predefined leak levels were tested for each leak model (0%-87%). Resuscitation devices were connected to a test lung (compliance 0.6 mL/cmH2O) and respiratory parameters were measured using respiratory function monitors before (patient interface) and after (actual) an induced leak at 40, 60, 80 inflations/min.

RESULTS

Three thousand six hundred inflations were analyzed. DLM showed a decrease in actual tidal volumes from 0%-87% leak with tidal volume differences (SIB 4.8 mL, TPR 2.9 mL), contrasting to minimal change for CLM (SIB -0.6 mL, TPR 0.3 mL). CLM demonstrated larger differences between patient interface and actual leak. The absolute difference at 60 inflations/min at 87% leak were SIB 37.5%, TPR 18.2% for CLM compared to SIB 4.6%, TPR 1.4% for DLM.

CONCLUSIONS

CLM may underestimate the impact of resuscitation device performance with poor correlation between patient interface and actual delivered volume. DLM demonstrates several advantages with a more accurate representation of face mask leak and will prove useful in modeling all systems delivering PPV.

Supraglottic airway in neonatal porcine model

BACKGROUND

Positive pressure ventilation (PPV) in the delivery room is routinely performed using a face mask attached to a ventilation device. In 2023, the Consensus of Science and Treatment Recommendations for neonatal resuscitation stated that a supraglottic airway (SGA) can be used for PPV if resources and training permits. However, there is very limited data on tidal volume (VT) delivery using SGAs. We aimed to compare VT delivery using five ventilation devices (i.e., self-inflating bag (SIB)), T-Piece resuscitator, flow-inflating bag (FIB), NextStepTM, and Fabian ventilator with an SGA at two compliance levels using a neonatal piglet model.

DESIGN/METHODS

Randomized crossover experimental animal trial using 10 mixed-breed neonatal piglets (1-3 days; 1.8-2.4 kg). Piglets were anesthetized, SGA placed, instrumented, and randomized to PPV for one minute with SIB with or without a respiratory function monitor (RFM), T-Piece resuscitator ± RFM, FIB ± RFM, NextStepTM, and Fabian Ventilator at two compliance levels. Compliance changes were achieved by placing a wrap around the piglets' chest and tightening it. Our primary outcome was targeted VT delivery of 5 mL/kg at 0.5 and 1.5 mL/cmH2O lung compliance.

RESULTS

At 0.5 mL/cmH2O compliance, mean(SD) expired VT with the NextStepTM was 5.0(0.1)mL/kg compared to Fabian 5.1(0.2), SIB 6.3(1.8), SIB + RFM 5.3(0.8), T-Piece 5.9(1.5), T-Piece+RFM 5.5(0.6), FIB 7.7(1.8), FIB + RFM 8.5(2.9)mL/kg. At 1.5 mL/cmH2O compliance, mean(SD) expired VT with the NextStepTM was 5.1(0.2)mL/kg compared to Fabian 5.1(0.2),SIB 11.6(3.4), SIB + RFM 7.1(1.8), T-Piece 9.8(1.8), T-Piece+RFM 7.9(1.3), FIB 12.6(3.2), FIB + RFM 9.2(1.4)mL/kg.

CONCLUSION

The NextStepTM provides consistent VT during PPV with little variation despite compliance changes. Clinical studies are warranted.

IMPACT

Current guidelines recommend fixed peak inflation pressure in resuscitation, linked to lung and brain injury. The NextStepTM Neonatal Resuscitator, a cost-effective device, offers volume-targeted positive pressure ventilation with consistent tidal volumes delivery. With two different compliances, the NextStepTM Neonatal Resuscitator delivered a consistent tidal volume similar to a mechanical ventilator. The NextStepTM Neonatal Resuscitator outperformed self-inflating or flow-inflating bags and T-Piece resuscitators to deliver targeted tidal volumes. The NextStepTM Neonatal Resuscitator could be an alternative ventilation device for neonatal resuscitation.

Chronic Inflammation Offers Hints About Viable Therapeutic Targets for Preeclampsia and Potentially Related Offspring Sequelae

The combination of hypertension with systemic inflammation during pregnancy is a hallmark of preeclampsia, but both processes also convey dynamic information about its antecedents and correlates (e.g., fetal growth restriction) and potentially related offspring sequelae. Causal inferences are further complicated by the increasingly frequent overlap of preeclampsia, fetal growth restriction, and multiple indicators of acute and chronic inflammation, with decreased gestational length and its correlates (e.g., social vulnerability). This complexity prompted our group to summarize information from mechanistic studies, integrated with key clinical evidence, to discuss the possibility that sustained or intermittent systemic inflammation-related phenomena offer hints about viable therapeutic targets, not only for the prevention of preeclampsia, but also the neurobehavioral and other developmental deficits that appear to be overrepresented in surviving offspring. Importantly, we feel that carefully designed hypothesis-driven observational studies are necessary if we are to translate the mechanistic evidence into child health benefits, namely because multiple pregnancy disorders might contribute to heightened risks of neuroinflammation, arrested brain development, or dysconnectivity in survivors who exhibit developmental problems later in life.

Randomised study of a new inline respiratory function monitor (Juno) to improve mask seal and delivered ventilation with neonatal manikins

BACKGROUND

Respiratory function monitors (RFMs) have been used extensively in manikin and infant studies yet have not become the standard of training. We report the outcomes of a new portable, lightweight RFM, the Juno, designed to show mask leak and deflation tidal volume to assist in positive pressure ventilation (PPV) competency training using manikins.

METHODS

Two leak-free manikins (preterm and term) were used. Participants provided PPV to manikins using two randomised devices, self-inflating bag (SIB) and T-piece resuscitator (TPR), with Juno display initially blinded then unblinded in four 90 s paired sequences, aiming for adequate chest wall rise and target minimal mask leak with appropriate target delivered volume when using the monitor.

RESULTS

49 experienced neonatal staff delivered 15 569 inflations to the term manikin and 14 580 inflations to the preterm. Comparing blinded to unblinded RFM display, there were significant reductions in all groups in the number of inflations out of target range volumes (preterm: SIB 22.6-6.6%, TPR 7.1-4.2% and term: SIB 54.8-37.8%, TPR 67.2-63.8%). The percentage of mask leak inflations >60% was reduced in preterm: SIB 20.7-7.2%, TPR 23.4-7.4% and in term: SIB 8.7-3.6%, TPR 23.5-6.2%).

CONCLUSIONS

Using the Juno monitor during simulated resuscitation significantly improved mask leak and delivered ventilation among otherwise experienced staff using preterm and term manikins. The Juno is a novel RFM that may assist in teaching and self-assessment of resuscitation PPV technique.

Brain MRI Injury Patterns across Gestational Age among Preterm Infants with Perinatal Asphyxia

INTRODUCTION

Brain injury patterns of preterm infants with perinatal asphyxia (PA) are underreported. We aimed to explore brain magnetic resonance imaging (MRI) findings and associated neurodevelopmental outcomes in these newborns.

METHODS

Retrospective multicenter study included infants with gestational age (GA) 24.0-36.0 weeks and PA, defined as ≥2 of the following: (1) umbilical cord pH ≤7.0, (2) 5-min Apgar score ≤5, and (3) fetal distress or systemic effects of PA. Findings were compared between GA <28.0 (group 1), 28.0-31.9 (group 2), and 32.0-36.0 weeks (group 3). Early MRI (<36 weeks postmenstrual age or <10 postnatal days) was categorized according to predominant injury pattern, and MRI around term-equivalent age (TEA, 36.0-44.0 weeks and ≥10 postnatal days) using the Kidokoro score. Adverse outcomes included death, cerebral palsy, epilepsy, severe hearing/visual impairment, or neurodevelopment <-1 SD at 18-24 months corrected age.

RESULTS

One hundred nineteen infants with early MRI (n = 94) and/or MRI around TEA (n = 66) were included. Early MRI showed predominantly hemorrhagic injury in groups 1 (56%) and 2 (45%), and white matter (WM)/watershed injury in group 3 (43%). Around TEA, WM scores were highest in groups 2 and 3. Deep gray matter (DGM) (aOR 15.0, 95% CI: 3.8-58.9) and hemorrhagic injury on early MRI (aOR 2.5, 95% CI: 1.3-4.6) and Kidokoro WM (aOR 1.3, 95% CI: 1.0-1.6) and DGM sub-scores (aOR 4.8, 95% CI: 1.1-21.7) around TEA were associated with adverse neurodevelopmental outcomes.

CONCLUSION

The brain injury patterns following PA in preterm infants differ across GA. Particularly DGM abnormalities are associated with adverse neurodevelopmental outcomes.

Positive Pressure Ventilation in Preterm Infants in the Delivery Room: A Review of Current Practices, Challenges, and Emerging Technologies

BACKGROUND

A major proportion of preterm neonates require positive pressure ventilation (PPV) immediately after delivery. PPV may be administered through a face mask (FM) or nasal prongs. Current literature indicates that either of these are associated with similar outcomes.

SUMMARY

Nonetheless, FM remains the most utilized and the best choice. However, most available FM sizes are too large for extremely preterm infants, which leads to mask leak and ineffective PPV. Challenges to providing effective PPV include poor respiratory drive, complaint chest wall, weak thoracic muscle, delayed liquid clearance, and surfactant deficiency in preterm infants. Mask leak, airway obstruction, poor technique, and inappropriate size are correctable causes of ineffective PPV. Visual assessment of chest rise is often used to assess the efficacy of PPV. However, its accuracy is debatable. Though end tidal CO2 may adjudge the effectiveness of PPV, clinical studies are limited. The compliance of a preterm lung is highly dynamic. The inflating pressure set on T-piece is constant throughout the resuscitation, but the lung volume and dynamics changes with every breath. This leads to huge fluctuations of tidal volume delivery and can trigger inflammatory cascade in preterm infants leading to brain and lung injury. Respiratory function monitoring in the delivery room has potential for guiding and optimizing delivery room resuscitation. This is, however, limited by high costs, complex information that is difficult to interpret during resuscitation, and absence of clinical trials.

KEY MESSAGES

This review summarizes the existing literature on PPV in preterm infants, the various aspects related to it such as the pathophysiology, interfaces, devices utilized to deliver it, appropriate technique, emerging technologies, and future directions.

Introducing a novel respiratory function monitor for neonatal resuscitation training

Background

A respiratory function monitor (RFM) gives immediate feedback, allowing clinicians to adjust face mask ventilation to correct leak or inappropriate tidal volumes. We audited the satisfaction of clinicians with a neonatal resuscitation training package, incorporating a novel RFM.

Methods

This was a mixed-methods study conducted at The Royal Women's Hospital, Melbourne, Australia. Clinicians were approached to complete a neonatal resuscitation training session. Participants watched a training video, then provided ventilation to term and preterm manikins first without, and then with, the RFM. Clinicians completed a survey after the session and undertook a follow-up session three months later. The primary outcome was participant satisfaction with the RFM. Secondary outcomes included participants' self-assessment of face mask leak and tidal volumes when using the RFM.

Results

Fifty clinicians completed both the initial and follow-up session. Participants reported high levels of satisfaction with the RFM for both term and preterm manikins: on a scale from 0, meaning "not at all", and 100, meaning "yes, for all resuscitations", the median response (interquartile range, IQR) was 82 (74-94) vs 81.5 (69-94.5). Levels of satisfaction were similar for less experienced and more experienced clinicians: median (IQR) 83 (77-93) vs 81 (71.5-95) respectively. When using the monitor, clinicians accurately self-assessed that they achieved leak below 30% and tidal volumes within the target range at least 80% of the time.

Conclusion

Clinicians of all experience levels had a high level of satisfaction with a training package including a novel RFM.

Mechanical ventilation induces brainstem inflammation in preterm fetal sheep

Background

Preterm infants have immature respiratory drive and often require prolonged periods of mechanical ventilation. Prolonged mechanical ventilation induces systemic inflammation resulting in ventilation-induced brain injury, however its effect on brainstem respiratory centers is unknown. We aimed to determine the effects of 24 h of mechanical ventilation on inflammation and injury in brainstem respiratory centres of preterm fetal sheep.

Methods

Preterm fetal sheep at 110 ± 1 days (d) gestation were instrumented to provide mechanical ventilation in utero. At 112 ± 1 d gestation, fetuses received either mechanical ventilation (VENT; n = 7; 3 ml/kg) for 24 h, or no ventilation (CONT; n = 6). At post-mortem, fetal brainstems were collected for assessment of mRNA and histological markers of inflammation and injury.

Results

In utero ventilation (IUV) did not alter any blood-gas parameters. IUV significantly increased systemic IL-6 and IL-8 concentrations over the 24 h period compared to CONT. The number of ameboid microglia within the nucleus tractus solitarius and the raphe nucleus increased in VENT fetuses (p < 0.05 for both vs. control). The % area fraction of GFAP + staining was not significantly higher within the preBötzinger complex (p = 0.067) and retrotrapezoid nucleus and parafacial respiratory group (p = 0.057) in VENT fetuses compared to CONT. Numbers of caspase-3 and TUNEL-positive cells were similar between groups. Gene expression (mRNA) levels of inflammation, injury, cell death and prostaglandin synthesis within the brainstem were similar between groups.

Conclusion

Mechanical ventilation induces a systemic inflammatory response with only moderate inflammatory effects within the brainstem respiratory centres of preterm fetal sheep.

Ventilation devices for neonatal resuscitation at birth: A systematic review and meta-analysis

Initial management of inadequate adaptation to extrauterine life relies on non-invasive respiratory support. Two types of devices are available: fixed pressure devices (FPD; T-pieces or ventilators) and hand driven pressure devices (HDPD; self- or flow-inflating bags). This systematic review and meta-analysis aims to compare clinical outcomes after neonatal resuscitation according to device type.

METHODS

Four databases were searched from inception to 2022, January. Search strategies included Mesh/Emtree terms as well as free language without any restriction. Randomized, quasi-randomized studies and prospective cohorts comparing the use of the two types of devices in neonatal resuscitation were included.

RESULTS

Nine studies recruiting 3621 newborns were included: 5 RCTs, 2 RCTs with interventions bundles and 2 prospective cohorts. Meta-analysis of the 5 RCTs demonstrated significant reductions in bronchopulmonary dysplasia (RR0,68[0,48-0,96]-NNT 31) and other respiratory outcomes: intubation in the delivery room (RR0,72[0,58-0,88]-NNT 13,4), mechanical ventilation requirements (RR0,81[0,67-0,96]-NNT 17) and duration (MD-1,54 days[-3,03- -0,05]), need for surfactant (RR0,79[0,64-0,96]-NNT 7,3). The overall analysis found a lower mortality in the FPD group (OR0,57[0,47-0,69]-NNT 12,7) and confirmed decreases in intubation, surfactant requirement and mechanical ventilation rates (OR 0,56[0,40-0,79]- NNT7,5; OR 0,67[0,55-0,82]-NNT10,7 and OR0,58[0,42-0,80]- NNT 7,4 respectively). The risk of cystic periventricular leukomalacia (cPVL) decreased significantly with FPD (OR0.59[0.41-0.85]-NNT 27). Pneumothorax rates were similar (OR0.82[0.44-1.52]).

CONCLUSION AND RELEVANCE

Resuscitation at birth with FPD improves respiratory transition and decreases BPD with a very low to moderate certainty of evidence. There is suggestion of decreases in mortality and cPVL. Further studies are still needed to confirm those results.

Association of infant and child health characteristics with the hazard of any medical condition or disability in Australian children

Background

The incidence of any medical condition (e.g., sight, hearing, and speech problems, blackouts, chronic pain etc.) or disability (e.g., limited use of arms or fingers, legs, and feet, or other physical long-term health condition limiting everyday activities etc.) have been increasing among Australian children in recent decades.

Objectives

This study assessed whether infant or child health characteristics might be predictors of subsequent medical conditions or disabilities in children in the first 15 years of life.

Methods

Using time to event data of 5107 children, obtained from the Birth cohort of the Longitudinal Study of Australian Children, the study estimated the incidence of any medical condition or disability using the survival analysis technique. This study followed up the children from birth to 14 or 15 years of age (2004–2018) and assessed the association of infant and child health characteristics (birthweight, gestational age, use of intensive care unit or ventilator during their neonatal age and obesity) with hazard of any medical condition or disability using the random effect parametric survival regression model. The infant characteristics were measured in the Wave 1 while the children were aged 0/1 year and obesity characteristics were measured longitudinally over all the waves up to 14/15 years of age.

Results

The hazard rate of any medical condition or disability for all participants was 26.13 per 1000 person-years among children in Australia. This hazard incidence rate was higher among low birthweight (39.07) children compared to the children of normal birthweight (24.89) children. The hazard rate also higher among obese (34.37) children compared to the normal weight children (24.82) and among those who had received after-birth ventilation or intensive care unit emergency services (36.87) compared to those who have not received these services (24.20). The parametric panel regression model also suggests that children with low birthweight were 1.43 times (Hazard Ratio: 1.43, 95% Confidence Interval: 1.05–1.94) more likely to have any medical condition or disability than children with normal birthweight. The time to event analyses also revealed that being recipient of after-birth emergencies (HR: 1.47, 95% CI: 1.23–1.75), being male children (HR: 1.30, 95% CI: 1.14–1.48) or being obese (HR: 1.38, 95% CI: 1.07–1.79) significantly increased the likelihood of the incidence of a medical condition or disability among children. The regression model was adjusted for socio-demographic characteristics of children and mothers..

Conclusions

The study findings suggest that infants with low birth weight, hospital emergency service use and children with obesity would benefit from additional health care monitoring to minimize the risk of any medical condition or disability.

Respiratory function monitoring to improve the outcomes following neonatal resuscitation: a systematic review and meta-analysis

IMPORTANCE

Animal and observational human studies report that delivery of excessive tidal volume (V_T) at birth is associated with lung and brain injury. Using a respiratory function monitor (RFM) to guide V_T delivery might reduce injury and improve outcomes.

OBJECTIVE

To determine whether use of an RFM in addition to clinical assessment versus clinical assessment alone during mask ventilation in the delivery room reduces in-hospital mortality and morbidity of infants <37 weeks' gestation.

STUDY SELECTION

Randomised controlled trials (RCTs) comparing RFM in addition to clinical assessment versus clinical assessment alone during mask ventilation in the delivery room of infants born <37 weeks' gestation.

DATA ANALYSIS

Risk of bias was assessed using Covidence Collaboration tool and pooled into a meta-analysis using a random-effects model. The primary outcome was death prior to discharge.

MAIN OUTCOME

Death before hospital discharge.

RESULTS

Three RCTs enrolling 443 infants were combined in a meta-analysis. The pooled analysis showed no difference in rates of death before discharge with an RFM versus no RFM, relative risk (RR) 95% (CI) 0.98 (0.64 to 1.48). The pooled analysis suggested a significant reduction for brain injury (a combination of intraventricular haemorrhage and periventricular leucomalacia) (RR 0.65 (0.48 to 0.89), p=0.006) and for intraventricular haemorrhage (RR 0.69 (0.50 to 0.96), p=0.03) in infants receiving positive pressure ventilation with an RFM versus no RFM.

CONCLUSION

In infants <37 weeks, an RFM in addition to clinical assessment compared with clinical assessment during mask ventilation resulted in similar in-hospital mortality, significant reduction for any brain injury and intraventricular haemorrhage. Further trials are required to determine whether RFMs should be routinely available for neonatal resuscitation.

Investigating Pathways of Ventilation Induced Brain Injury on Cerebral White Matter Inflammation and Injury After 24 h in Preterm Lambs

Initiation of respiratory support in the delivery room increases the risk and severity of brain injury in preterm neonates through two major pathways: an inflammatory pathway and a haemodynamic pathway. The relative contribution of each pathway on preterm brain injury is not known. We aimed to assess the role of the inflammatory and haemodynamic pathway on ventilation-induced brain injury (VIBI) in the preterm lamb. Fetal lambs (125 ± 1 day gestation) were exteriorised, instrumented and ventilated with a high tidal-volume (V_T) injurious strategy for 15 min either with placental circulation intact to induce the inflammatory pathway only (INJ_INF; n = 7) or umbilical cord occluded to induce both the inflammatory and haemodynamic pathways (INJ_INF+HAE; n = 7). Sham controls were exteriorised but not ventilated (SHAM; n = 5) while unoperated controls (UNOP; n = 7) did not undergo fetal instrumentation. Fetuses were returned in utero following intervention and the ewe allowed to recover. Arterial blood gases and plasma were sampled periodically. Twenty-four hours following intervention, lambs were delivered and maintained on non-injurious ventilation for ∼40 min then brains were collected post-mortem for immunohistochemistry and RT-qPCR to assess inflammation, vascular pathology and cell death within white matter regions. Compared to INJ_INF lambs, INJ_INF+HAE lambs achieved a consistently higher V_T during injurious ventilation and carotid blood flow was significantly lower than baseline by the end of ventilation. Throughout the 24 h recovery period, systemic arterial IL-6 levels of INJ_INF+HAE lambs were significantly higher than SHAM while there was no difference between INJ_INF and SHAM animals. At 24 h, mRNA expression levels of pro-inflammatory cytokines, tight junction proteins, markers of cell death, and histological injury indices of gliosis, blood vessel protein extravasation, oligodendrocyte injury and cell death were not different between groups. Injurious ventilation, irrespective of strategy, did not increase brain inflammation or injury 24 h later when compared to control animals. However, the haemodynamic pathway did influence carotid blood flow adaptations during injurious ventilation and increased systemic arterial IL-6 that may underlie long-term pathology. Future studies are required to further characterise the pathways and their long-term effects on VIBI.

Circulating extracellular vesicles activate the pyroptosis pathway in the brain following ventilation-induced lung injury

BACKGROUND

Mechanical ventilation of preterm newborns causes lung injury and is associated with poor neurodevelopmental outcomes. However, the mechanistic links between ventilation-induced lung injury (VILI) and brain injury is not well defined. Since circulating extracellular vesicles (EVs) are known to link distant organs by transferring their cargos, we hypothesized that EVs mediate inflammatory brain injury associated with VILI.

METHODS

Neonatal rats were mechanically ventilated with low (10 mL/kg) or high (25 mL/kg) tidal volume for 1 h on post-natal day 7 followed by recovery for 2 weeks. Exosomes were isolated from the plasma of these rats and adoptively transferred into normal newborn rats. We assessed the effect of mechanical ventilation or exosome transfer on brain inflammation and activation of the pyroptosis pathway by western blot and histology.

RESULTS

Injurious mechanical ventilation induced similar markers of inflammation and pyroptosis, such as increased IL-1β and activated caspase-1/gasdermin D (GSDMD) in both lung and brain, in addition to inducing microglial activation and cell death in the brain. Isolated EVs were enriched for the exosomal markers CD9 and CD81, suggesting enrichment for exosomes. EVs isolated from neonatal rats with VILI had increased caspase-1 but not GSDMD. Adoptive transfer of these EVs led to neuroinflammation with microglial activation and activation of caspase-1 and GSDMD in the brain similar to that observed in neonatal rats that were mechanically ventilated.

CONCLUSIONS

These findings suggest that circulating EVs can contribute to the brain injury and poor neurodevelopmental outcomes in preterm infants with VILI through activation of GSDMD.

Role of Neonatal Behavioral Neurological Assessment combined with magnetic resonance diffusion tensor imaging in evaluating white matter development in preterm infants

OBJECTIVES

To study the correlation of fractional anisotropy (FA) on magnetic resonance diffusion tensor imaging with Neonatal Behavioral Neurological Assessment (NBNA) score in preterm infants, and to study the role of FA in evaluating white matter development from the perspective of imaging.

METHODS

A prospective study was performed for 98 preterm infants who were admitted to the Neonatal Intensive Care Unit of the Third Affiliated Hospital of Zhengzhou University within 24 hours after birth from October 2016 to January 2020. According to the results of NBNA, they were divided into an abnormal group with 51 infants (NBNA score <37) and a normal group with 47 infants (NBNA score ≥37). The FA values of 10 regions of interest were collected and compared between the two groups. The correlations of FA value and umbilical arterial blood gas pH value with the NBNA score were analyzed.

RESULTS

Compared with the normal group, the abnormal group had significantly lower FA value of the posterior limb of the internal capsule and umbilical arterial blood pH (P<0.05). The FA value of the posterior limb of the internal capsule and umbilical arterial blood pH were positively correlated with the NBNA score (r=0.584 and 0.604 respectively, P<0.001), and the FA value of the posterior limb of the internal capsule was positively correlated with umbilical arterial blood pH (r=0.426, P<0.05).

CONCLUSIONS

The FA value of the posterior limb of the internal capsule can quantitatively reflect white matter development in preterm infants and is correlated with the NBNA score. The combination of the two indices can help to evaluate white matter development in preterm infants more accurately and objectively. Citation.

Devices for Administering Ventilation at Birth: A Systematic Review

CONTEXT

Positive pressure ventilation (PPV) is the most important intervention during neonatal resuscitation.

OBJECTIVE

To compare T-piece resuscitators (TPRs), self-inflating bags (SIBs), and flow-inflating bags for newborns receiving PPV during delivery room resuscitation.

DATA SOURCES

Medline, Embase, Cumulative Index to Nursing and Allied Health Literature, Cochrane Database of Systematic Reviews, and trial registries (inception to December 2020).

STUDY SELECTION

Randomized, quasi-randomized, interrupted time series, controlled before-and-after, and cohort studies were included without language restrictions.

DATA EXTRACTION

Two researchers independently extracted data, assessed the risk of bias, and evaluated the certainty of evidence. The primary outcome was in-hospital mortality. When appropriate, data were pooled by using fixed-effect models.

RESULTS

Meta-analysis of 4 randomized controlled trials (1247 patients) revealed no significant difference between TPR and SIB for in-hospital mortality (risk ratio 0.74; 95% confidence interval [CI] 0.40 to 1.34). Resuscitation with a TPR resulted in a shorter duration of PPV (mean difference -19.8 seconds; 95% CI -27.7 to -12.0 seconds) and lower risk of bronchopulmonary dysplasia (risk ratio 0.64; 95% CI 0.43 to 0.95; number needed to treat 32). No differences in clinically relevant outcomes were found in 2 randomized controlled trials used to compare SIBs with and without positive end-expiratory pressure valves. No studies used to evaluate flow-inflating bags were found.

LIMITATIONS

Certainty of evidence was very low or low for most outcomes.

CONCLUSIONS

Resuscitation with a TPR compared with an SIB reduces the duration of PPV and risk of bronchopulmonary dysplasia. A strong recommendation cannot be made because of the low certainty of evidence. There is insufficient evidence to determine the effectiveness of positive end-expiratory pressure valves when used with SIBs.

Delivery room resuscitation and short-term outcomes of extremely preterm and extremely low birth weight infants: a multicenter survey in North China

Background:

Delivery room resuscitation assists preterm infants, especially extremely preterm infants (EPI) and extremely low birth weight infants (ELBWI), in breathing support, while it potentially exerts a negative impact on the lungs and outcomes of preterm infants. This study aimed to assess delivery room resuscitation and discharge outcomes of EPI and ELBWI in China.

Methods:

The clinical data of EPI (gestational age [GA] <28 weeks) and ELBWI (birth weight [BW] <1000 g), admitted within 72 h of birth in 33 neonatal intensive care units from five provinces and cities in North China between 2017 and 2018, were analyzed. The primary outcomes were delivery room resuscitation and risk factors for delivery room intubation (DRI). The secondary outcomes were survival rates, incidence of bronchopulmonary dysplasia (BPD), and risk factors for BPD.

Results:

A cohort of 952 preterm infants were enrolled. The incidence of DRI, chest compressions, and administration of epinephrine was 55.9% (532/952), 12.5% (119/952), and 7.0% (67/952), respectively. Multivariate analysis revealed that the risk factors for DRI were GA <28 weeks (odds ratio [OR], 3.147; 95% confidence interval [CI], 2.082–4.755), BW <1000 g (OR, 2.240; 95% CI, 1.606–3.125), and antepartum infection (OR, 1.429; 95% CI, 1.044–1.956). The survival rate was 65.9% (627/952) and was dependent on GA. The rate of BPD was 29.3% (181/627). Multivariate analysis showed that the risk factors for BPD were male (OR, 1.603; 95% CI, 1.061–2.424), DRI (OR, 2.094; 95% CI, 1.328–3.303), respiratory distress syndrome exposed to ≥2 doses of pulmonary surfactants (PS; OR, 2.700; 95% CI, 1.679–4.343), and mechanical ventilation ≥7 days (OR, 4.358; 95% CI, 2.777–6.837). However, a larger BW (OR, 0.998; 95% CI, 0.996–0.999), antenatal steroid (OR, 0.577; 95% CI, 0.379–0.880), and PS use in the delivery room (OR, 0.273; 95% CI, 0.160–0.467) were preventive factors for BPD (all P < 0.05).

Conclusion:

Improving delivery room resuscitation and management of respiratory complications are imperative during early management of the health of EPI and ELBWI.

Increased peak end-expiratory pressure in ventilated preterm lambs changes cerebral microvascular perfusion: direct synchrotron microangiography assessment

Positive end-expiratory pressure (PEEP) improves oxygenation in mechanically ventilated preterm neonates by preventing lung collapse. However, high PEEP may alter cerebral blood flow secondarily to the increased intrathoracic pressure, predisposing to brain injury. The precise effects of high PEEP on cerebral hemodynamics in the preterm brain are unknown. We aimed to assess the effect of PEEP on microvessels in the preterm brain by using synchrotron radiation (SR) microangiography, which enables in vivo real-time high-resolution imaging of the cerebral vasculature. Preterm lambs (0.8 gestation, n = 4) were delivered via caesarean section, anesthetized, and ventilated. SR microangiography of the right cerebral hemisphere was performed with iodine contrast administered into the right carotid artery during PEEP ventilation of 5 and 10 cmH₂O. Carotid blood flow was measured using an ultrasonic flow probe placed around the left carotid artery. An increase of PEEP from 5 to 10 cmH₂O increased the diameter of small cerebral vessels (<150 µm) but decreased the diameter of larger cerebral vessels (>500 µm) in all four lambs. Additionally, the higher PEEP increased the cerebral contrast transit time in three of the four lambs. Carotid blood flow increased in two lambs, which also had increased carbon dioxide levels during PEEP 10. Our results suggest that PEEP of 10 cmH₂O alters the preterm cerebral hemodynamics, with prolonged cerebral blood flow transit and engorgement of small cerebral microvessels likely due to the increased intrathoracic pressure. These microvascular changes are generally not reflected in global assessment of cerebral blood flow or oxygenation.NEW & NOTEWORTHY An increase of positive end-expiratory pressure (PEEP) from 5 to 10 cmH₂O increased the diameter of small cerebral vessels (<150 µm) but decreased the diameter of larger cerebral vessels (>500 µm). This suggests increased intrathoracic pressure due to high PEEP can drive microvessel engorgement in the preterm brain, which may play a role in cerebrovascular injury.

Respiratory Support of the Preterm Neonate: Lessons About Ventilation-Induced Brain Injury From Large Animal Models

Many preterm neonates require mechanical ventilation which increases the risk of cerebral inflammation and white matter injury in the immature brain. In this review, we discuss the links between ventilation and brain injury with a focus on the immediate period after birth, incorporating respiratory support in the delivery room and subsequent mechanical ventilation in the neonatal intensive care unit. This review collates insight from large animal models in which acute injurious ventilation and prolonged periods of ventilation have been used to create clinically relevant brain injury patterns. These models are valuable resources in investigating the pathophysiology of ventilation-induced brain injury and have important translational implications. We discuss the challenges of reconciling lung and brain maturation in commonly used large animal models. A comprehensive understanding of ventilation-induced brain injury is necessary to guide the way we care for preterm neonates, with the goal to improve their neurodevelopmental outcomes.

Ventilation, oxidative stress and risk of brain injury in preterm newborn

Preterm infants have an increased risk of cognitive and behavioral deficits and cerebral palsy compared to term born babies. Especially before 32 weeks of gestation, infants may require respiratory support, but at the same time, ventilation is known to induce oxidative stress, increasing the risk of brain injury. Ventilation may cause brain damage through two pathways: localized cerebral inflammatory response and hemodynamic instability. During ventilation, the most important causes of pro-inflammatory cytokine release are oxygen toxicity, barotrauma and volutrauma. The purpose of this review was to analyze the mechanism of ventilation-induced lung injury (VILI) and the relationship between brain injury and VILI in order to provide the safest possible respiratory support to a premature baby. As gentle ventilation from the delivery room is needed to reduce VILI, it is recommended to start ventilation with 21–30% oxygen, prefer a non-invasive respiratory approach and, if mechanical ventilation is required, prefer low Positive End-Expiratory Pressure and tidal volume.

Effects of sustained inflation pressure during neonatal cardiopulmonary resuscitation of asphyxiated piglets

Background

Sustained inflation (SI) during chest compression (CC = CC+SI) has been recently shown as an alternative method during cardiopulmonary resuscitation in neonates. However, the optimal peak inflation pressure (PIP) of SI during CC+SI to improve ROSC and hemodynamic recovery is unknown.

Objective

To examine if different PIPs of SI during CC+SI will improve ROSC and hemodynamic recovery in severely asphyxiated piglets.

Methods

Twenty-nine newborn piglets (1–3 days old) were anesthetized, intubated, instrumented and exposed to 30-min normocapnic hypoxia followed by asphyxia. Piglets were randomized into four groups: CC+SI with a PIP of 10 cmH₂O (CC+SI_PIP_10, n = 8), a PIP of 20 cmH₂O (CC+SI_PIP_20, n = 8), a PIP of 30 cmH₂O (CC+SI_PIP_30, n = 8), and a sham-operated control group (n = 5). Heart rate, arterial blood pressure, carotid blood flow, cerebral oxygenation, and respiratory parameters were continuously recorded throughout the experiment.

Results

Baseline parameters were similar between all groups. There was no difference in asphyxiation (duration and degree) between intervention groups. PIP correlated positively with tidal volume (V_T) and inversely with exhaled CO₂ during cardiopulmonary resuscitation. Time to ROSC and rate of ROSC were similar between piglets resuscitated with CC+SI_PIP_10, CC+SI_PIP_20, and CC+SI_PIP_30 cmH₂O: median (IQR) 75 (63–193) sec, 94 (78–210) sec, and 85 (70–90) sec; 5/8 (63%), 7/8 (88%), and 3/8 (38%) (p = 0.56 and p = 0.12, respectively). All piglets that achieved ROSC survived to four hours post-resuscitation. Piglets resuscitated with CC+SI_PIP_30 cmH₂O exhibited increased concentrations of pro-inflammatory cytokines interleukin-1β and tumour necrosis factor-α in the frontoparietal cerebral cortex (both p<0.05 vs. sham-operated controls).

Conclusion

In asphyxiated term newborn piglets resuscitated by CC+SI, the use of different PIPs resulted in similar time to ROSC, but PIP at 30 cmH₂O showed a larger V_T delivery, lower exhaled CO₂ and increased tissue inflammatory markers in the brain.

Does Antenatal Betamethasone Alter White Matter Brain Development in Growth Restricted Fetal Sheep?

Fetal growth restriction (FGR) is a common complication of pregnancy often associated with neurological impairments. Currently, there is no treatment for FGR, hence it is likely these babies will be delivered prematurely, thus being exposed to antenatal glucocorticoids. While there is no doubt that antenatal glucocorticoids reduce neonatal mortality and morbidities, their effects on the fetal brain, particularly in FGR babies, are less well recognized. We investigated the effects of both short- and long-term exposure to antenatal betamethasone treatment in both FGR and appropriately grown fetal sheep brains. Surgery was performed on pregnant Border-Leicester Merino crossbred ewes at 105-110 days gestation (term ~150 days) to induce FGR by single umbilical artery ligation (SUAL) or sham surgery. Ewes were then treated with a clinical dose of betamethasone (11.4 mg intramuscularly) or saline at 113 and 114 days gestation. Animals were euthanized at 115 days (48 h following the initial betamethasone administration) or 125 days (10 days following the initial dose of betamethasone) and fetal brains collected for analysis. FGR fetuses were significantly smaller than controls (115 days: 1.68 ± 0.11 kg vs. 1.99 ± 0.11 kg, 125 days: 2.70 ± 0.15 kg vs. 3.31 ± 0.20 kg, P < 0.001) and betamethasone treatment reduced body weight in both control (115 days: 1.64 ± 0.10 kg, 125 days: 2.53 ± 0.10 kg) and FGR fetuses (115 days: 1.41 ± 0.10 kg, 125 days: 2.16 ± 0.17 kg, P < 0.001). Brain: body weight ratios were significantly increased with FGR (P < 0.001) and betamethasone treatment (P = 0.002). Within the fetal brain, FGR reduced CNPase-positive myelin staining in the subcortical white matter (SCWM; P = 0.01) and corpus callosum (CC; P = 0.01), increased GFAP staining in the SCWM (P = 0.02) and reduced the number of Olig2 cells in the periventricular white matter (PVWM; P = 0.04). Betamethasone treatment significantly increased CNPase staining in the external capsule (EC; P = 0.02), reduced GFAP staining in the CC (P = 0.03) and increased Olig2 staining in the SCWM (P = 0.04). Here we show that FGR has progressive adverse effects on the fetal brain, particularly within the white matter. Betamethasone exacerbated growth restriction in the FGR offspring, but betamethasone did not worsen white matter brain injury.

Effect of sustained inflations and intermittent positive pressure ventilation on bronchopulmonary dysplasia or death among neonatal: A protocol for systematic review

BACKGROUND

Sustained Inflations (SI) and Intermittent Positive Pressure Ventilation (IPPV) are two interventions to prevent Bronchopulmonary dysplasia (BPD). The aim of this study is to assess the effect of these two interventions.

METHODS

The databases of PubMed, EMBASE, and Cochrane Central Register of Controlled Trials (CENTRAL) will be comprehensively searched from inception to September 2019. All RCTs and quasi-RCTs which compare the efficacy of SI vs IPPV among preterm infants are eligible. We will assess the methodological quality using the Cochrane Handbook version 5.1.0. A meta-analysis will be performed using RevMan 5.3 software and the results will be presented using risk ratios (RRs) and 95% confidence intervals (CIs).

CONCLUSIONS

This study will provide strong evidence for assessing the effect of SI and IPPV on BPD or death among preterm infants.

PROSPERO REGISTRATION NUMBER

CRD42019135816.

Neurovascular effects of umbilical cord blood-derived stem cells in growth-restricted newborn lambs : UCBCs for perinatal brain injury

Background

Neonatal ventilation exacerbates brain injury in lambs with fetal growth restriction (FGR), characterized by neuroinflammation and reduced blood-brain barrier integrity, which is normally maintained by the neurovascular unit. We examined whether umbilical cord blood stem cell (UCBC) treatment stabilized the neurovascular unit and reduced brain injury in preterm ventilated FGR lambs.

Methods

Surgery was performed in twin-bearing pregnant ewes at 88 days’ gestation to induce FGR in one fetus. At 127 days, FGR and appropriate for gestational age (AGA) lambs were delivered, carotid artery flow probes and umbilical lines inserted, lambs intubated and commenced on gentle ventilation. Allogeneic ovine UCBCs (25 × 10⁶ cells/kg) were administered intravenously to lambs at 1 h of life. Lambs were ventilated for 24 h and then euthanized.

Results

FGR (n = 6) and FGR+UCBC (n = 6) lambs were growth restricted compared to AGA (n = 6) and AGA+UCBC (n = 6) lambs (combined weight, FGR 2.3 ± 0.4 vs. AGA 3.0 ± 0.3 kg; p = 0.0002). UCBC therapy did not alter mean arterial blood pressure or carotid blood flow but decreased cerebrovascular resistance in FGR+UCBC lambs. Circulating TNF-α cytokine levels were lower in FGR+UCBC vs. FGR lambs (p < 0.05). Brain histopathology showed decreased neuroinflammation and oxidative stress, increased endothelial cell proliferation, pericyte stability, and greater integrity of the neurovascular unit in FGR+UCBC vs. FGR lambs.

Conclusions

Umbilical cord blood stem cell therapy mitigates perinatal brain injury due to FGR and ventilation, and the neuroprotective benefits may be mediated by stabilization of the neurovascular unit.

Enhanced monitoring during neonatal resuscitation

Immediately after birth through spontaneous breaths, infants' clear lung liquid replacing it with air, and gradually establishing a functional residual capacity to achieve gas exchange. Most infants start breathing independently after birth and ~3% of infants who require positive pressure ventilation. When newborns fail to start breathing the current neonatal resuscitation guidelines recommend initiatingpositive pressure ventilationusing a face mask and a ventilation device. Adequate ventilation is the cornerstone of successful neonatal resuscitation; therefore, it is mandatory that anybody involved in neonatal resuscitation is trained in mask ventilation techniques. One of the main problems with mask ventilation is that it is very subjective with direct feedback lacking and not uncommonly, the resuscitator does not realise that their technique is unsatisfactory. Many studies have shown that monitoring tidal volume and leak around the mask or endotracheal tube enables the resuscitator to identify the problem and adjust their technique to reduce the leak and deliver and appropriate tidal volume. This chapter discusses the currently available monitoring devices used during stabilization/resuscitation in the delivery room.

Punctate white matter lesions of preterm infants: Risk factor analysis

AIM

Punctate white matter lesions (PWML) are frequently detected in preterm infants undergoing brain MRI at term equivalent age (TEA). The aims of this study were to assess prevalence of PWML and to identify risk factors for PWML in VLBW infants.

METHODS

Brain MRI scans obtained at TEA and clinical charts of a consecutive sample of very low birth weight (VLBW) infants admitted to Gaslini Children's Hospital NICU between 2012 and 2016 were retrospectively analyzed. MRI protocol included Susceptibility Weighted Imaging (SWI) sequence in order to identify hemosiderin depositions as a result of previous microbleeds. PWML were classified according to their number (≤6 lesions and >6 lesions) and signal characteristics (SWI+ lesions and SWI- lesions). Univariate and multivariable analysis were performed in order to identify risk factors for PWML (as a whole) and for each subgroup of PWML.

RESULTS

321 VLBW infants were included. PWML were identified in 61 subjects (19%), 26 of whom (8% of the study population) had more than 6 lesions. Risk factors for PWML (as a whole) were higher birth weight (OR = 1.001; p = 0.04) and absent or incomplete antenatal steroid course (OR = 2.13; p = 0.02). Risk factors for >6 PWML were need for intubation (OR = 11.9; p = 0.003) and higher Apgar score at 5 min (OR = 1.8; p = 0.02). Presence of GMH-IVH was the only identified risk factor for SWI + lesions.

CONCLUSIONS

Our results confirm the high prevalence of PWML among VLBW infants. Differentiation between SWI+ and SWI- lesions is crucial as they have different risk factors and may likely represent two different entities.

Impact of delivered tidal volume on the occurrence of intraventricular haemorrhage in preterm infants during positive pressure ventilation in the delivery room

BACKGROUND AND OBJECTIVES

Delivery of inadvertent high tidal volume (V_T) during positive pressure ventilation (PPV) in the delivery room is common. High V_T delivery during PPV has been associated with haemodynamic brain injury in animal models. We examined if V_T delivery during PPV at birth is associated with brain injury in preterm infants <29 weeks' gestation.

METHODS

A flow-sensor was placed between the mask and the ventilation device. V_T values were compared with recently described reference ranges for V_T in spontaneously breathing preterm infants at birth. Infants were divided into two groups: V_T<6  mL/kg or V_T>6 mL/kg (normal and high V_T, respectively). Brain injury (eg, intraventricular haemorrhage (IVH)) was assessed using routine ultrasound imaging within the first days after birth.

RESULTS

A total of 165 preterm infants were included, 124 (75%) had high V_T and 41 (25%) normal V_T. The mean (SD) gestational age and birth weight in high and normal V_T group was similar, 26 (2) and 26 (1) weeks, 858 (251) g and 915 (250) g, respectively. IVH in the high V_T group was diagnosed in 63 (51%) infants compared with 5 (13%) infants in the normal V_T group (P=0.008).Severe IVH (grade III or IV) developed in 33/124 (27%) infants in the high V_T group and 2/41 (6%) in the normal V_T group (P=0.01).

CONCLUSIONS

High V_T delivery during mask PPV at birth was associated with brain injury. Strategies to limit V_T delivery during mask PPV should be used to prevent high V_T delivery.

Dose-dependent exacerbation of ventilation-induced lung injury by erythropoietin in preterm newborn lambs

Erythropoietin (EPO) is being trialled in preterm infants to reduce brain injury, but high doses increase lung injury in ventilated preterm lambs. We aimed to determine whether early administration of lower doses of EPO could reduce ventilation-induced lung injury and systemic inflammation in preterm lambs. Ventilation was initiated in anaesthetized preterm lambs [125 ± 1 (SD) days gestation] using an injurious strategy for the first 15 min. Lambs were subsequently ventilated with a protective strategy for a total of 2 h. Lambs were randomized to receive either intravenous saline (Vent; n = 7) or intravenous 300 ( n = 5), 1,000 (EPO1000; n = 5), or 3,000 (EPO3000; n = 5) IU/kg of human recombinant EPO via an umbilical vein. Lung tissue was collected for molecular and histological assessment of inflammation and injury and compared with unventilated control lambs (UVC; n = 8). All ventilated groups had similar blood gas and ventilation parameters, but EPO1000 lambs had a lower fraction of inspired oxygen requirement and lower alveolar–arterial difference in oxygen. Vent and EPO lambs had increased lung interleukin (IL)-1β, IL-6, and IL-8 mRNA, early lung injury genes connective tissue growth factor, early growth response protein 1, and cysteine-rich 61, and liver serum amyloid A3 mRNA compared with UVCs; no difference was observed between Vent and EPO groups. Histological lung injury was increased in Vent and EPO groups compared with UVCs, but EPO3000 lambs had increased lung injury scores compared with VENT only. Early low-doses of EPO do not exacerbate ventilation-induced lung inflammation and injury and do not provide any short-term respiratory benefit. High doses (≥3,000 IU/kg) likely exacerbate lung inflammation and injury in ventilated preterm lambs.

NEW & NOTEWORTHY Trials are ongoing to assess the efficacy of erythropoietin (EPO) to provide neuroprotection for preterm infants. However, high doses of EPO increase ventilation-induced lung injury (VILI) in preterm lambs. We investigated whether early lower doses of EPO may reduce VILI. We found that lower doses did not reduce, but did not increase, VILI, while high doses (≥3,000 IU/kg) increase VILI. Therefore, lower doses of EPO should be used in preterm infants, particularly those receiving respiratory support.

Sustained inflations and avoiding mechanical ventilation to prevent death or bronchopulmonary dysplasia: a meta-analysis

Sustained inflations and avoidance of endotracheal mechanical ventilation (eMV) are delivery room interventions aimed at preventing bronchopulmonary dysplasia (BPD). Their effectiveness is the subject of the present meta-analysis.The databases MEDLINE, EMBASE and CENTRAL were searched for randomised controlled trials (RCTs) of preterm infants that compared: 1) sustained inflations with intermittent positive-pressure ventilation; and 2) a non-intubated strategy of respiratory support with one that prescribed eMV at an earlier stage. Data extraction and analysis followed the standard methods of the Cochrane Collaboration. The primary outcome was death or BPD, defined as need for oxygen or positive pressure treatment at 36 weeks' postmenstrual age.Avoiding eMV (nine RCTs, 3486 infants) reduced the risk of death or BPD, with a risk ratio of 0.90 (95% CI 0.84-0.97) and a number needed to treat of 35. After sustained inflations (six RCTs, 854 infants), the risk ratio was 0.85 (95% CI 0.65-1.12). A current multicentre RCT of sustained inflations in very preterm infants was halted for increased early mortality in the sustained inflations arm.While strategies aimed at avoiding eMV had a small but significant impact on preventing BPD, sustained inflations had no effect and may even increase mortality in very preterm infants.

Neuropathology as a consequence of neonatal ventilation in premature growth-restricted lambs

Fetal growth restriction (FGR) and prematurity are associated with high risk of brain injury and long-term neurological deficits. FGR infants born preterm are commonly exposed to mechanical ventilation, but it is not known whether ventilation differentially induces brain pathology in FGR infants compared with appropriate for gestational age (AGA) infants. We investigated markers of neuropathology in moderate- to late-preterm FGR lambs, compared with AGA lambs, delivered by caesarean birth and ventilated under standard neonatal conditions for 24 h. FGR was induced by single umbilical artery ligation in fetal sheep at 88-day gestation (term, 150 days). At 125-day gestation, FGR and AGA lambs were delivered, dried, intubated, and commenced on noninjurious ventilation, with surfactant administration at 10 min. A group of unventilated FGR and AGA lambs at the same gestation was also examined. Over 24 h, circulating pH, Po₂, and lactate levels were similar between groups. Ventilated FGR lambs had lower cerebral blood flow compared with AGA lambs ( P = 0.01). The brain of ventilated FGR lambs showed neuropathology compared with unventilated FGR, and unventilated and ventilated AGA lambs, with increased apoptosis (caspase-3), blood-brain barrier dysfunction (albumin extravasation), activated microglia (Iba-1), and increased expression of cellular oxidative stress (4-hydroxynonenal). The neuropathologies seen in the ventilated FGR brain were most pronounced in the periventricular and subcortical white matter but also evident in the subventricular zone, cortical gray matter, and hippocampus. Ventilation of preterm FGR lambs increased brain injury compared with AGA preterm lambs and unventilated FGR lambs, mediated via increased vascular permeability, neuroinflammation and oxidative stress.

The effects of rhEPO intervention for perinatal intrauterine herpes virus infection on preventing brain injury in preterm infants

The ability of recombinant human erythropoietin (rhEPO) to protect preterm infants against perinatal intrauterine herpes virus infection-induced brain injury was studied. In total, 120 women infected with perinatal intrauterine herpes virus were randomized into four groups: A, B, C and D, and were given 1,500 IU (mother, pre-partum), 3,000 IU (mother, pre-partum), 250 IU/kg (infant, post-natal), and no rhEPO, respectively. Hemoglobin (Hb), reticulocyte (Ret), hematocrit (Hct), neuron specific enolase (NSE), myelin basic protein (MBP), and S100 protein B (S100B) levels were measured immediately (T₀) and at 1 week (T₁), 2 weeks (T₂), and 4 weeks (T₃) post-delivery. Linear regression analysis was performed to analyze inter-indicator correlation, and ROC risk models were established to determine the predictive value of Hb, Ret and Hct for brain injury immediately after delivery. The brain injury incidence rate of group A (10%) was significantly lower than group D (33.3%) and group B (6.7%) significantly lower than groups C (26.7%) and D. At T₀, Hb, Ret and Hct in groups A and B were significantly higher than in group C and D, while from T₁ to T₃, groups A, B and C showed significantly higher values than group D. NSE, MBP and S100B showed an inverse trend, with groups A and B lower at T₀ and groups A, B and C lower from T₁-T₃. Hb and NSE, MBP and S100B were negatively correlated, while no correlation was found between Ret and NSE, MBP and S100B. Finally, Hct and NSE, MBP and S100B were negatively correlated. The optimal cut-off values for Hb and Hct for brain injury diagnosis immediately post-partum were 170 g/l (sensitivity 99%, specificity 95.7%) and 28.5% (sensitivity 79.4%, specificity 100%), respectively. Ret did not show predictive value. In conclusion, pre-partum rhEPO treatment showed greater protective effects than post-natal administration, and this may be the regulation of Hb and Hct levels in post-natal preterm infants. In addition, a dose-dependent effect was displayed.

Complex interactions between hypoxia-ischemia and inflammation in preterm brain injury

Children surviving preterm birth have a high risk of disability, particularly cognitive and learning problems. There is extensive clinical and experimental evidence that disability is now primarily related to dysmaturation of white and gray matter, defined by failure of oligodendrocyte maturation and neuronal dendritic arborization, rather than cell death alone. The etiology of this dysmaturation is multifactorial, with contributions from hypoxia-ischemia, infection/inflammation and barotrauma. Intriguingly, these factors can interact to both increase and decrease damage. In this review we summarize preclinical and clinical evidence that all of these factors trigger secondary or chronic inflammation and gliosis. Thus, we hypothesize that these shared pathological features play a key role in a final common pathway that leads to the impaired neural maturation and connectivity and cognitive/motor impairments that are commonly observed in infants born preterm. This raises the possibility that secondary or chronic inflammation may be a viable therapeutic target for delayed interventions to improve neurodevelopmental outcomes after preterm birth.

WHAT THIS PAPER ADDS

Hypoxia-ischemia, infection/inflammation, and barotrauma/volutrauma all contribute to preterm brain injury. Multiple different triggers of preterm brain injury are associated with central nervous system dysmaturation. Secondary brain inflammation may be a viable target to improve neurodevelopment after preterm birth.

Ventilation Prior to Umbilical Cord Clamping Improves Cardiovascular Stability and Oxygenation in Preterm Lambs After Exposure to Intrauterine Inflammation

Background: Delaying umbilical cord clamping until after aeration of the lung (physiological-based cord clamping; PBCC) maintains cardiac output and oxygenation in preterm lambs at birth, however, its efficacy after intrauterine inflammation is not known. Given the high incidence of chorioamnionitis in preterm infants, we investigated whether PBCC conferred any benefits compared to immediate cord clamping (ICC) in preterm lambs exposed antenatally to 7 days of intrauterine inflammation. Methods: Ultrasound guided intraamniotic injection of 20 mg Lipopolysaccharide (from E. coli:055:B5) was administered to pregnant ewes at 0.8 gestation. Seven days later, ewes were anesthetized, preterm fetuses exteriorised via cesarean section, and instrumented for continuous measurement of pulmonary, systemic and cerebral pressures and flows, and systemic, and cerebral oxygenation. Lambs were then randomized to either PBCC, whereupon ventilation was initiated and maintained for 3 min prior to umbilical cord clamping, or ICC where the umbilical cord was cut and ventilation initiated 30 s later. Ventilation was maintained for 30 min. Results: ICC caused a rapid fall in systemic (by 25%) and cerebral (by 11%) oxygen saturation in ICC lambs, concurrent with a rapid increase in carotid arterial pressure and heart rate. The overshoot in carotid arterial pressure was sustained in ICC lambs for the first 20 min of the study. PBCC maintained cardiac output and prevented the fall in cerebral oxygen delivery at birth. PBCC lambs had lower respiratory compliance and higher respiratory requirements throughout the study. Conclusion: PBCC mitigated the adverse effects of ICC on oxygenation and cardiac output, and therefore could be more beneficial in preterm babies exposed to antenatal inflammation as it maintains cardiac output and oxygen delivery. The increased respiratory requirements require further investigation in this sub-group of preterm infants.

Effects of Intrauterine Inflammation on Cortical Gray Matter of Near-Term Lambs

Introduction: Ventilation causes cerebral white matter inflammation and injury, which is exacerbated by intrauterine inflammation. However, the effects on cortical gray matter are not well-known. Our aim was to examine the effect of ventilation on the cerebral cortex of near-term lambs exposed to intrauterine inflammation. Method:Pregnant ewes at 119 ± 1 days gestation received an intra-amniotic injection of saline or lipopolysaccharide (LPS; 10 mg). Seven days later, lambs were randomized to either a high tidal volume injurious ventilation strategy (INJ_SALN = 6, INJ_LPSN = 5) or a protective ventilation strategy (PROT_SALN = 5, PROT_LPSN = 6). Respiratory parameters, heart rate and blood gases were monitored during the neonatal period. At post-mortem, the brain was collected and processed for immunohistochemical assessment. Neuronal density (NeuN), apoptotic cell death (caspase 8 and TUNEL), microglial density (Iba-1), astrocytic density (GFAP), and vascular protein extravasation (sheep serum) were assessed within the frontal, parietal, temporal and occipital lobes of the cerebral cortex. Results:A significant reduction in the number of neurons in all cortical layers except 4 was observed in LPS-exposed lambs compared to controls (layer #1: p = 0.041; layers #2 + 3: p = 0.023; layers #5 + 6: p = 0.016). LPS treatment caused a significant increase in gray matter area, indicative of edema. LPS+ventilation did not cause apoptotic cell death in the gray matter. Astrogliosis was not observed following PROT or INJ ventilation, with or without LPS exposure. LPS exposure was associated with vascular protein extravasation. Conclusion:Ventilation had little effect on gray matter inflammation and injury. Intrauterine inflammation reduced neuronal cell density, caused edema of the cortical gray matter, and blood vessel extravasation in the brain of near-term lambs.

Reducing Brain Injury of Preterm Infants in the Delivery Room

Cerebrovascular injury is one of the major detrimental consequences of preterm birth. Recent studies have focused their attention on factors that contribute to the development of brain lesions immediately after birth. Among those factors, hypothermia and lower cerebral oxygen saturation during delivery room resuscitation and high tidal volumes delivered during respiratory support are associated with increased risk of severe neurologic injury. In preterm infants, knowledge about causes and prevention of brain injury must be applied before and at birth. Preventive and therapeutic approaches, including correct timing of cord clamping, monitoring of physiological changes during delivery room resuscitation using pulse oximetry, respiratory function monitoring, near infrared spectroscopy, and alpha EEG, may minimize brain injury, Furthermore, postnatal administration of caffeine or other potential novel treatments (e.g., proangiogenic therapies, antioxidants, hormones, or stem cells) might improve long-term neurodevelopmental outcomes in preterm infants.

Management of Extremely Low Birth Weight Infants in Delivery Room

Extremely low birth weight (ELBW) infants are particularly vulnerable at birth, and stabilization in the delivery room (DR) remains challenging. After birth, ELBW infants are at high risk for the development of thermal dysregulation, respiratory insufficiency, and hemodynamic instability due to their immature physiology and anatomy. Although successful stabilization facilitates the transition and reduces acute morbidity, suboptimal care in the DR could cause long-term sequelae. This review addresses the challenges in stabilization in the DR and current neonatal resuscitation guidelines and recommendations.

Incidence and characteristics of positive pressure ventilation delivered to newborns in a US tertiary academic hospital

INTRODUCTION

The Neonatal Resuscitation Program (NRP) guidelines recommend positive pressure ventilation (PPV) in the first 60s of life to support perinatal transition in non-breathing newborns. Our aim was to describe the incidence and characteristics of newborn PPV using real-time observation in the delivery unit.

METHODS

Prospective, observational, quality improvement study conducted at a tertiary academic hospital. Deliveries during randomized weekday/evening 8-h shifts were attended by a trained observer. Intervention data were recorded for all newborns with gestational age (GA) ≥34wks that received PPV. Descriptive summaries and Kruskal-Wallis test for continuous variables and Fisher's exact test for categorical variables were used to compare characteristics.

RESULTS

Of 1135 live deliveries directly observed over 18mos, 64 (6%) newborns with a mean GA 39±2wks received PPV: Median time from birth to warmer was 20s (IQR 15-22s); PPV was initiated within 60s of life in 29 (45%) and between 60 and 90s of life in 17 (27%). PPV duration was <120s in 38 (60%). Seven/21 (33%) newborns that received PPV after vaginal delivery were not pre-identified and resuscitation team was alerted after delivery. We found no association between PPV start time and duration of PPV (p=0.86).

CONCLUSION

We observed that most (94%) term newborns spontaneously initiate respirations. In over half observed deliveries receiving PPV, time to initiation of PPV was greater than 60s (longer than recommended). Compliance with current NRP guidelines is difficult, and it's not clear whether it is the recommendations or the training to achieve PPV recommendations that should be modified.

Reliability of Single-Use PEEP-Valves Attached to Self-Inflating Bags during Manual Ventilation of Neonates--An In Vitro Study

Introduction

International resuscitation guidelines suggest to use positive end-expiratory pressure (PEEP) during manual ventilation of neonates. Aim of our study was to test the reliability of self-inflating bags (SIB) with single-use PEEP valves regarding PEEP delivery and the effect of different peak inflation pressures (PIP) and ventilation rates (VR) on the delivered PEEP.

Methods

Ten new single-use PEEP valves from 5 manufacturers were tested by ventilating an intubated 1kg neonatal manikin containing a lung model with a SIB that was actuated by an electromechanical plunger device. Standard settings: PIP 20cmH₂O, VR 60/min, flow 8L/min. PEEP settings of 5 and 10cmH₂O were studied. A second test was conducted with settings of PIP 40cmH₂O and VR 40/min. The delivered PEEP was measured by a respiratory function monitor (CO₂SMO⁺).

Results

Valves from one manufacturer delivered no relevant PEEP and were excluded. The remaining valves showed a continuous decay of the delivered pressure during expiration. The median (25^th and 75^th percentile) delivered PEEP with standard settings was 3.4(2.7–3.8)cmH₂O when set to 5cmH₂O and 6.1(4.9–7.1)cmH₂O when set to 10cmH₂O. Increasing the PIP from 20 to 40 cmH₂O led to a median (25^th and 75^th percentile) decrease in PEEP to 2.3(1.8–2.7)cmH₂O and 4.3(3.2–4.8)cmH₂O; changing VR from 60 to 40/min led to a PEEP decrease to 2.8(2.1–3.3)cmH₂O and 5.0(3.5–6.2)cmH₂O for both PEEP settings.

Conclusion

Single-use PEEP valves do not reliably deliver the set PEEP. PIP and VR have an effect on the delivered PEEP. Operators should be aware of these limitations when manually ventilating neonates.

A Novel Prototype Neonatal Resuscitator That Controls Tidal Volume and Ventilation Rate: A Comparative Study of Mask Ventilation in a Newborn Manikin

The objective of this randomized controlled manikin trial was to examine tidal volume (V_T) delivery and ventilation rate during mask positive pressure ventilation (PPV) with five different devices, including a volume-controlled prototype Next Step™ device for neonatal resuscitation. We hypothesized that V_T and rate would be closest to target with the Next Step™. Twenty-five Neonatal Resuscitation Program providers provided mask PPV to a newborn manikin (simulated weight 1 kg) in a randomized order with a self-inflating bag (SIB), a disposable T-piece, a non-disposable T-piece, a stand-alone resuscitation system T-piece, and the Next Step™. All T-pieces used a peak inflation pressure of 20 cmH₂O and a positive end-expiratory pressure of 5 cmH₂O. The participants were instructed to deliver a 5 mL/kg V_T (rate 40-60/min) for 1 min with each device and each of three test lungs with increasing compliance of 0.5, 1.0, and 2.0 mL/cmH₂O. V_T and ventilation rate were compared between devices and compliance levels (linear mixed model). All devices, except the Next Step™ delivered a too high V_T, up to sixfold the target at the 2.0-mL/cmH₂O compliance. The Next Step™ V_T was 26% lower than the target in the low compliance. The ventilation rate was within target with the Next Step™ and SIB, and slightly lower with the T-pieces. In conclusion, routinely used newborn resuscitators over delivered V_T, whereas the Next Step™ under delivered in the low compliant test lung. The SIB had higher V_T and rate than the T-pieces. More research is needed on volume-controlled delivery room ventilation.

Ventilation-Induced Brain Injury in Preterm Neonates: A Review of Potential Therapies

Mechanical ventilation is a risk factor for cerebral inflammation and brain injury in preterm neonates. The risk increases proportionally with the intensity of treatment. Recent studies have shown that cerebral inflammation and injury can be initiated in the delivery room. At present, initiation of intermittent positive pressure ventilation (IPPV) in the delivery room is one of the least controlled interventions a preterm infant will likely face. Varying pressures and volumes administered shortly after birth are sufficient to trigger pathways of ventilation-induced lung and brain injury. The pathways involved in ventilation-induced brain injury include a complex inflammatory cascade and haemodynamic instability, both of which have an impact on the brain. However, regardless of the strategy employed to deliver IPPV, any ventilation has the potential to have an impact on the immature brain. This is particularly important given that preterm infants are already at a high risk for brain injury simply due to immaturity. This highlights the importance of improving the initial respiratory support in the delivery room. We review the mechanisms of ventilation-induced brain injury and discuss the need for, and the most likely, current therapeutic agents to protect the preterm brain. These include therapies already employed clinically, such as maternal glucocorticoid therapy and allopurinol, as well as other agents, such as erythropoietin, human amnion epithelial cells and melatonin, already showing promise in preclinical studies. Their mechanisms of action are discussed, highlighting their potential for use immediately after birth.