Reduced oxygen concentration for the resuscitation of infants with congenital diaphragmatic hernia

Hemodynamic precision to guide surgical timing for neonates with congenital diaphragmatic hernia: a narrative review

Despite a near universal approach focused on physiologic stabilization prior to surgical repair of congenital diaphragmatic hernia (CDH), a condition with significant morbidity and mortality, there remains a lack of consensus, or even guidance, on the appropriate timing for diaphragmatic reconstruction. Hemodynamic-directed care has increasingly been incorporated into the post-natal, peri-operative care of CDH, including assessments of pulmonary hypertension and ventricular dysfunction. Herein, we discuss the integration of targeted neonatal echocardiography and hemodynamic-based assessments to guide precision-directed care and inform selection of the optimal surgical repair window in this complex, heterogeneous patient population.

Respiratory Support Strategies for Surgical Neonates: A Review

Neonates with congenital conditions which require surgical management frequently experience respiratory distress. This review discusses the management of pulmonary complications and the respiratory support strategies for four conditions: oesophageal atresia-tracheoesophageal fistula (OA-TOF), congenital diaphragmatic hernia (CDH), congenital lung malformations (CLM), and anterior abdominal wall defects (AWD). Mechanical ventilation techniques which can reduce the risk of ventilator-induced lung injury (VILI) are discussed, as well as the use of non-invasive respiratory support modes. While advances in perioperative respiratory support have improved outcomes in infants with OA-TOF, managing respiratory distress in premature OA-TOF neonates remains a challenge. In CDH infants, a randomised trial has suggested that conventional ventilation may improve outcomes compared to high-frequency ventilation. Echocardiographic assessment is essential in the management of CDH infants with pulmonary hypertension. Lung-protective ventilation settings may lower the rate of postoperative complications in symptomatic CLM infants, but there remains debate regarding the choice of expectant versus surgical management in neonates with asymptomatic CLMs. Infants with AWDs can require ventilation due to pulmonary hypoplasia, but the effects of this on their long-term respiratory health are poorly understood. As surgical techniques continue to evolve and novel ventilation techniques become available, prospective multi-centre studies will be required to define the optimal respiratory support strategies for neonatal surgical conditions that affect lung function.

Golden hour management of infants with congenital diaphragmatic hernia: 15 year experience at a high-volume center

OBJECTIVE

To review the evolution of golden hour management and outcomes for infants with congenital diaphragmatic hernia (CDH).

STUDY DESIGN

Retrospective single center cohort study of infants with CDH born 2008-2023 at a quaternary children's hospital. Infants were grouped into 3 epochs: 2008-2013, 2014-2018, and 2019-2023. Outcome measures included extracorporeal membrane oxygenation therapy and survival.

RESULT

There were 454 infants, including 106 (2008-2013), 156 (2014-2018), and 192 (2019-2023). Despite increased disease severity, survival improved over time, from 71% (2008-2013) to 82% (2014-2018) and 83% (2019-2023), p = 0.02 for trend, with no difference in ECMO utilization.

CONCLUSION

Management of infants with CDH continues to evolve with ongoing experience at our high-volume center. Despite increasing severity of illness, survival outcomes have improved over time. In the absence of clinical trial data, observational data should be evaluated rigorously to inform care in a data-driven manner.

Update on Management and Outcomes of Congenital Diaphragmatic Hernia

Infants with congenital diaphragmatic hernia (CDH) benefit from comprehensive multidisciplinary teams that have experience in caring for the unique and complex issues associated with CDH. Despite prenatal referral to specialized high-volume centers, advanced ventilation strategies and pulmonary hypertension management, and extracorporeal membrane oxygenation, mortality and morbidity remain high. These infants have unique and complex issues that begin in fetal and infant life, but persist through adulthood. Here we will review the literature and share our clinical care pathway for neonatal care and follow up. While many advances have occurred in the past few decades, our work is just beginning to continue to improve the mortality, but also importantly the morbidity of CDH.

Oxygen saturation targets in neonatal care: A narrative review

Optimal oxygenation requires the delivery of oxygen to meet tissue metabolic demands while minimizing hypoxic pulmonary vasoconstriction and oxygen toxicity. Oxygen saturation by pulse oximetry (SpO2) is a continuous, non-invasive method for monitoring oxygenation. The optimal SpO2 target varies during pregnancy and neonatal period. Maternal SpO2 should ideally be ≥95 % to ensure adequate fetal oxygenation. Term neonates can be resuscitated with an initial oxygen concentration of 21 %, while moderately preterm infants require 21-30 %. Extremely preterm infants may need higher FiO2, followed by titration to desired SpO2 targets. During the NICU course, extremely preterm infants managed with an 85-89 % SpO2 target compared to 90-94 % are associated with a reduced incidence of severe retinopathy of prematurity (ROP) requiring treatment, but with higher mortality. During the later stages of ROP progression, studies suggest that higher SpO2 targets may help limit progression. A target SpO2 of 90-95 % is generally reasonable for term infants with respiratory disease or pulmonary hypertension, with few exceptions such as severe acidosis, therapeutic hypothermia, and possibly dark skin pigmentation, where 93-98 % may be preferred. Infants with cyanotic heart disease and single-ventricle physiology have lower SpO2 targets to avoid pulmonary over-circulation. In low- and middle-income countries (LMICs), the scarcity of oxygen blenders and continuous monitoring may pose a challenge, increasing the risks of both hypoxia and hyperoxia, which can lead to mortality and ROP, respectively. Strategies to mitigate hyperoxia among preterm infants in LMICs are urgently needed to reduce the incidence of ROP.

Delivery Room Management of Infants with Surgical Conditions

Delivery room resuscitation of infants with surgical conditions can be complex and depends on an experienced and cohesive multidisciplinary team whose performance is more important than that of any individual team member. Existing resuscitation algorithms were not developed for infants with congenital anomalies, and delivery room resuscitation is largely dictated by expert opinion extrapolating physiologic expectations from infants without anomalies. As prenatal diagnosis rates improve, there is an increased ability to plan for the unique delivery room needs of infants with surgical conditions. In this review, we share expert opinion, including our center's delivery room management for neonatal noncardiac surgical conditions, and highlight knowledge gaps and the need for further studies and evidence-based practice to be incorporated into the delivery room care of infants with surgical conditions. Future research in this area is essential to move from an expert-based approach to a data-driven approach to improve and individualize delivery room resuscitation of infants with surgical conditions.

Diaphragmatic Defects in Infants: Acute Management and Repair

Congenital diaphragmatic hernia (CDH) is a complex and highly variable disease process that should be treated at institutions with multidisciplinary teams designed for their care. Treatment in the neonatal period focuses on pulmonary hypoplasia, pulmonary hypertension, and cardiac dysfunction. Extracorporeal membrane oxygenation (ECMO) can be considered in patients refractory to medical management. Repair of CDH early during the ECMO course seems to improve mortality compared with other times for surgical intervention. The choice of surgical approach to CDH repair should consider the patient's physiologic status and the surgeon's familiarity with the operative approaches available, recognizing the pros/cons of each technique.

Closed-loop oxygen system in late preterm/term, ventilated infants with different severities of respiratory disease

AIM

To evaluate closed-loop automated oxygen control (CLAC) in ventilated infants >33 weeks of gestation with different respiratory disease severities.

METHODS

Infants were studied on two consecutive days for 6 h each day. They were randomised to receive standard care or standard care with CLAC (Oxygenie) first. Analyses were performed of the results of infants with or without an FiO₂  ≥ 0.3 and infants with congenital diaphragmatic hernia (CDH).

RESULTS

Thirty-one infants with a median (IQR) gestational age of 37.9 (37.1-38.9) weeks were studied at a median postmenstrual age (IQR) of 38.9 (37.4-39.8) weeks. In infants with an FiO₂  ≥ 0.3 (n = 8), CLAC increased the time spent in target oxygen range (92-96%) by 61.6% (p = 0.018), whereas in infants with an FiO₂  < 0.3, the time in target was increased by 3.8% (p = 0.019). During CLAC, only infants with an FiO₂  ≥ 0.3 spent less time in hyperoxemia (SpO₂  > 96%) (p = 0.012) and hyperoxemic episodes were shorter (p = 0.012). In both groups, CLAC reduced the duration of desaturations (SpO₂  < 92%, p < 0.001). In CDH infants, CLAC increased the time spent in target oxygen range by 34% (p = 0.036) and the median duration of desaturations was reduced (p = 0.028).

CONCLUSION

CLAC may be more useful in infants with more severe respiratory distress.

Special consideration in neonatal resuscitation

Delivery room resuscitation of neonates is performed according to evidence-based neonatal resuscitation guidelines. Neonatal resuscitation guidelines focus on the resuscitation of newborns suffering from perinatal asphyxia. Special considerations are needed when resuscitating newborns in locations other than the delivery room and for newborns with congenital anomalies. In this review, we examine the resuscitation of newborns at home and in the emergency department and highlight special considerations for resuscitating newborns with specific congenital anomalies. In addition, we explore the resuscitation of neonates in the neonatal intensive care unit and discuss the potential use of pediatric advanced life support guidelines. Finally, we highlight the importance of simulation to prepare teams for neonatal resuscitations. This review aims to prepare healthcare professionals in all disciplines caring for neonates at risk for requiring resuscitation under special circumstances.

Operative repair in congenital diaphragmatic hernia: How long do we really need to wait?

OBJECTIVE

To analyze preoperative cardiopulmonary support and define preoperative stability relative to timing of surgical repair for CDH neonates not on ECMO.

STUDY DESIGN

We retrospectively analyzed repeated measures of oxygenation index (OI; Paw*FiO₂×100/PaO₂) among 158 neonates for temporal preoperative trends. We defined physiologic stability using OI and characterized ventilator days and discharge age relative to delay in repair beyond physiologic stability.

RESULTS

The OI in the first 24 h of life was temporally reliable and representative of the preoperative mean (ICC 0.70, 95% CI 0.61-0.77). A pre-operative OI of ≤ 9.4 (AUC 0.95) was predictive of survival. Surgical delay after an OI ≤ 9.4 resulted in increased ventilator days (1.4, 95% CI 1.1-1.9) and discharge age (1.5, 95% CI 1.2-2.0). When prospectively applied to a subsequent cohort, an OI ≤ 9.4 was again reflective of physiologic stability prior to repair.

CONCLUSION

OI values are temporally reliable and change minimally after 24 h age. Delay in surgical repair of CDH beyond initial stability increases ventilator days and discharge age without a survival benefit.

LEVEL OF EVIDENCE

Prognosis study, Level III.

Neonatal and fetal therapy of congenital diaphragmatic hernia-related pulmonary hypertension

Congenital diaphragmatic hernia (CDH) is a complex malformation characterised by a triad of pulmonary hypoplasia, pulmonary hypertension (PH) and cardiac ventricular dysfunction. Much of the mortality and morbidity in CDH is largely accounted for by PH, especially when persistent beyond the neonatal period and refractory to available treatment. Gentle ventilation, haemodynamic optimisation and pulmonary vasodilation constitute the foundations of neonatal treatment of CDH-related PH (CDH-PH). Moreover, early prenatal diagnosis, the ability to assess severity and the developmental nature of the condition generate the perfect rationale for fetal therapy. Shortcomings of currently available clinical therapies in combination with increased understanding of CDH pathophysiology have spurred experimental drug trials, exploring new therapeutic mechanisms to tackle CDH-PH. We herein discuss clinically available neonatal and fetal therapies specifically targeting CDH-PH and review the most promising experimental treatments and future research avenues.

Outcomes of neonatal congenital diaphragmatic hernia in a non-ECMO center in a middle-income country: a retrospective cohort study

BACKGROUND

Most studies examining survival of neonates with congenital diaphragmatic hernia (CDH) are in high-income countries. We aimed to describe the management, survival to hospital discharge rate, and factors associated with survival of neonates with unilateral CDH in a middle-income country.

METHODS

We retrospectively reviewed the medical notes of neonates with unilateral CDH admitted to a pediatric intensive care unit (PICU) in a tertiary referral center over a 15-year period, from 2003-2017. We described the newborns' respiratory care pathways and then compared baseline demographic, hemodynamic, and respiratory indicators between survivors and non-survivors. The primary outcome measure was survival to hospital discharge.

RESULTS

Altogether, 120 neonates were included with 43.3% (52/120) diagnosed antenatally. Stabilization occurred in 38.3% (46/120) with conventional ventilation, 13.3% (16/120) with high-frequency intermittent positive-pressure ventilation, and 22.5% (27/120) with high frequency oscillatory ventilation. Surgical repair was possible in 75.0% (90/120). The overall 30-day survival was 70.8% (85/120) and survival to hospital discharge was 66.7% (80/120). Survival to hospital discharge tended to improve over time (p > 0.05), from 56.0% to 69.5% before and after, respectively, a service reorganization. For those neonates who could be stabilized and operated on, 90.9% (80/88) survived to hospital discharge. The commonest post-operative complication was infection, occurring in 43.3%. The median survivor length of stay was 32.5 (interquartile range 18.8-58.0) days. Multiple logistic regression modelling showed vaginal delivery (odds ratio [OR] = 4.8; 95% confidence interval [CI] [1.1-21.67]; p = 0.041), Apgar score [Formula: see text] 7 at 5 min (OR = 6.7; 95% CI [1.2-36.3]; p = 0.028), and fraction of inspired oxygen (FiO₂) < 50% at 24 h (OR = 89.6; 95% CI [10.6-758.6]; p < 0.001) were significantly associated with improved survival to hospital discharge.

CONCLUSIONS

We report a survival to hospital discharge rate of 66.7%. Survival tended to improve over time, reflecting a greater critical volume of cases and multi-disciplinary care with early involvement of the respiratory team resulting in improved transitioning from PICU. Vaginal delivery, Apgar score [Formula: see text] 7 at 5 min, and FiO₂ < 50% at 24 h increased the likelihood of survival to hospital discharge.

Inhaled Nitric Oxide at Birth Reduces Pulmonary Vascular Resistance and Improves Oxygenation in Preterm Lambs

Resuscitation with 21% O₂ may not achieve target oxygenation in preterm infants and in neonates with persistent pulmonary hypertension of the newborn (PPHN). Inhaled nitric oxide (iNO) at birth can reduce pulmonary vascular resistance (PVR) and improve PaO₂. We studied the effect of iNO on oxygenation and changes in PVR in preterm lambs with and without PPHN during resuscitation and stabilization at birth. Preterm lambs with and without PPHN (induced by antenatal ductal ligation) were delivered at 134 d gestation (term is 147–150 d). Lambs without PPHN were ventilated with 21% O₂, titrated O₂ to maintain target oxygenation or 21% O₂ + iNO (20 ppm) at birth for 30 min. Preterm lambs with PPHN were ventilated with 50% O₂, titrated O₂ or 50% O₂ + iNO. Resuscitation with 21% O₂ in preterm lambs and 50%O₂ in PPHN lambs did not achieve target oxygenation. Inhaled NO significantly decreased PVR in all lambs and increased PaO₂ in preterm lambs ventilated with 21% O₂ similar to that achieved by titrated O₂ (41 ± 9% at 30 min). Inhaled NO increased PaO₂ to 45 ± 13, 45 ± 20 and 76 ± 11 mmHg with 50% O₂, titrated O₂ up to 100% and 50% O₂ + iNO, respectively, in PPHN lambs. We concluded that iNO at birth reduces PVR and FiO₂ required to achieve target PaO₂.

Congenital diaphragmatic hernia: a narrative review of controversies in neonatal management

The consequences of most hernias can be immediately corrected by surgical repair. However, this isn't always the case for children born with a congenital diaphragmatic hernia. The derangements in physiology encountered immediately after birth result from pulmonary hypoplasia and hypertension caused by herniation of abdominal contents into the chest early in lung development. This degree of physiologic compromise can vary from mild to severe. Postnatal management of these children remains controversial. Although heavily studied, multi-institutional randomized controlled trials are lacking to help determine what constitutes best practice. Additionally, the results of the many studies currently within the literature that have investigated differing aspect of care (i.e., inhaled nitric oxide, ventilator type, timing of repair, role of extracorporeal membrane oxygenation, etc.) are difficult to interpret due to the small numbers investigated, the varying degree of physiologic compromise, and the contrasting care that exists between institutions. The aim of this paper is to review areas of controversy in the care of these complex kids, mainly: the use of fraction of inspired oxygen, surfactant therapy, gentle ventilation, mode of ventilation, medical management of pulmonary hypertension (inhaled nitric oxide, sildenafil, milrinone, bosentan, prostaglandins), the utilization of extracorporeal membrane oxygenation, and the timing of surgical repair.

Knowledge Gaps in the Fetal to Neonatal Transition of Infants With a Congenital Diaphragmatic Hernia

Clinical research for infants born with a congenital diaphragmatic hernia (CDH) has until recently mainly focused on advances in prenatal and postnatal treatment. However, during the early perinatal transition period there are major physiological adaptations. For most infants these changes will happen uneventfully, but for CDH infants this marks the beginning of serious respiratory complications. In recent years, there is emerging evidence that the clinical management during the perinatal stabilization period in the delivery room may influence postnatal outcomes. Herein, we discuss major knowledge gaps and novel concepts that aim to optimize fetal to neonatal transition for infants with CDH. One such novel and interesting approach is performing resuscitation with an intact umbilical cord, the efficacy of this procedure is currently being investigated in several clinical trials. Furthermore, close evaluation of neonatal physiological parameters in the first 24 h of life might provide early clues concerning the severity of lung hypoplasia and the risk of adverse outcomes. We will provide an overview of trending concepts and discuss potential areas for future research.

Respiratory Support of Infants With Congenital Diaphragmatic Hernia

Optimisation of respiratory support of infants with congenital diaphragmatic hernia (CDH) is critical. Infants with CDH often have severe lung hypoplasia and abnormal development of their pulmonary vasculature, leading to ventilation perfusion mismatch. It is vital that lung protective ventilation strategies are employed during both initial stabilisation and post-surgical repair to avoid ventilator induced lung damage and oxygen toxicity to prevent further impairment to an already diminished gas-exchanging environment. There is a lack of robust evidence for the routine use of surfactant therapy during initial resuscitation of infants with CDH and thus administration cannot be recommended outside clinical trials. Additionally, inhaled nitric oxide has been shown to have no benefit in reducing the mortality rates of infants with CDH. Other therapeutic agents which beneficially act on pulmonary hypertension are currently being assessed in infants with CDH in randomised multicentre trials. The role of novel ventilatory modalities such as closed loop automated oxygen control, liquid ventilation and heliox therapy may offer promise for infants with CDH, but the benefits need to be determined in appropriately designed clinical trials.

Perinatal stabilisation of infants born with congenital diaphragmatic hernia: a review of current concepts

Congenital diaphragmatic hernia (CDH) is associated with high mortality rates and significant pulmonary morbidity, mainly due to disrupted lung development related to herniation of abdominal organs into the chest. Pulmonary hypertension is a major contributor to both mortality and morbidity, however, treatment modalities are limited. Novel prenatal and postnatal interventions, such as fetal surgery and medical treatments, are currently under investigation. Until now, the perinatal stabilisation period immediately after birth has been relatively overlooked, although optimising support in these early stages may be vital in improving outcomes. Moreover, physiological parameters obtained from the perinatal stabilisation period could serve as early predictors of adverse outcomes, thereby facilitating both prevention and early treatment of these conditions. In this review, we focus on the perinatal stabilisation period by discussing the current delivery room guidelines in infants born with CDH, the physiological changes occurring during the fetal-to-neonatal transition in CDH, novel delivery room strategies and early predictors of adverse outcomes. The combination of improvements in the perinatal stabilisation period and early prediction of adverse outcomes may mitigate the need for specific postnatal management strategies.

Left-sided congenital diaphragmatic hernia: can we improve survival while decreasing ECMO?

BACKGROUND

Mortality and ECMO rates for congenital diaphragmatic hernia (CDH) remain ~30%. In 2016, we changed our CDH guidelines to minimize stimulation while relying on preductal oxygen saturation, lower mean airway pressures, stricter criteria for nitric oxide (iNO), and inotrope use. We compared rates of ECMO, survival, and survival without ECMO between the two epochs.

DESIGN/METHODS

Retrospective review of left-sided CDH neonates at the University of Utah/Primary Children's Hospital NICUs during pre (2003-2015, n = 163) and post (2016-2019, n = 53) epochs was conducted. Regression analysis controlled for defect size and intra-thoracic liver.

RESULTS

Following guideline changes, we identified a decrease in ECMO (37 to 13%; p = 0.001) and an increase in survival without ECMO (53 to 79%, p = 0.0001). Overall survival increased from 74 to 89% (p = 0.035).

CONCLUSION(S)

CDH management guideline changes focusing on minimizing stimulation, using preductal saturation and less aggressive ventilator/inotrope support were associated with decreased ECMO use and improved survival.

Initiating resuscitation before umbilical cord clamping in infants with congenital diaphragmatic hernia: a pilot feasibility trial

BACKGROUND

Infants with congenital diaphragmatic hernia (CDH) often experience hypoxaemia with acidosis immediately after birth. The traditional approach in the delivery room is immediate cord clamping followed by intubation. Initiating resuscitation prior to umbilical cord clamping (UCC) may support this transition.

OBJECTIVES

To establish the safety and feasibility of intubation and ventilation prior to UCC for infants with CDH. To compare short-term outcomes between trial participants and matched controls treated with immediate cord clamping before intubation and ventilation.

DESIGN

Single-arm, single-site trial of infants with CDH and gestational age ≥36 weeks. Infants were placed on a trolley immediately after birth and underwent intubation and ventilation, with UCC performed after qualitative CO₂ detection. The primary feasibility endpoint was successful intubation prior to UCC. Prespecified safety and physiological outcomes were compared with historical controls matched for prognostic variables using standard bivariate tests.

RESULTS

Of 20 enrolled infants, all were placed on the trolley, and 17 (85%) infants were intubated before UCC. The first haemoglobin and mean blood pressure at 1 hour of life were significantly higher in trial participants than controls. There were no significant differences between groups for subsequent blood pressure values, vasoactive medications, inhaled nitric oxide or extracorporeal membrane oxygenation. Blood gas and oxygenation index values did not differ between groups at any point.

CONCLUSIONS

Intubation and ventilation prior to UCC is safe and feasible among infants with CDH. The impact of this approach on clinically relevant outcomes deserves investigation in a randomised trial.

Neurodevelopmental impairment in children with congenital diaphragmatic hernia: Not an uncommon complication for survivors

PURPOSE

To evaluate neurodevelopmental impairment (NDI) in children born with congenital diaphragmatic hernia (CDH).

METHODS

Using a defined search strategy, a systematic review was conducted to define the incidence and types of NDI, to report abnormal neuroimaging findings and to evaluate possible NDI predictors. A meta-analysis was performed on comparative studies reporting risk factors for NDI, using RevMan 5.3.

RESULTS

Of 3541 CDH children (33 studies), 829 (23%) had NDI, with a higher incidence in CDH survivors who received ECMO treatment (49%) vs. those who had no ECMO (22%; p<0.00001). NDI included neuromuscular hypotonia (42%), hearing (13%) and visual (8%) impairment, neurobehavioral issues (20%), and learning difficulties (31%). Of 288 survivors that had postnatal neuroimaging, 49% had abnormal findings. The main risk factors for NDI were severe pulmonary hypoplasia, large defect size, ECMO use.

CONCLUSIONS

NDI is a relevant problem for CDH survivors, affecting 1 in 4. The spectrum of NDI covers all developmental domains and ranges from motor and sensory (hearing, visual) deficits to cognitive, language, and behavioral impairment. Further studies should be designed to better understand the pathophysiology of NDI in CDH children and to longitudinally monitor infants born with CDH to correct risk factors that can be modifiable.

LEVEL OF EVIDENCE

Level III.

Oxygen and pulmonary vasodilation: The role of oxidative and nitrosative stress

Respiratory failure complicates up to 2% of live births and contributes significantly to neonatal morbidity and mortality. Under these conditions, supplemental oxygen is required to support oxygen delivery to the brain and other organs, and to prevent hypoxic pulmonary vasoconstriction. However, therapeutic oxygen is also a source of reactive oxygen species that produce oxidative stress, along with multiple intracellular systems that contribute to the production of free radicals in pulmonary endothelium and vascular smooth muscle. These free radicals cause vasoconstriction, act on multiple sites of the nitric oxide pathway to reduce cGMP-mediated vasodilation, and nitrate and inactivate essential proteins such as surfactant. In addition to oxygen, antenatal stressors such as placental insufficiency, maternal diabetes, and fetal growth restriction increase pulmonary and vascular oxidant stress and may amplify the adverse effects of oxygen. Moreover, the effects of free radical damage may extend well beyond infancy as suggested by the increased risk of childhood malignancy after neonatal exposure to hyperoxia. Antioxidant therapy is theoretically promising, but there are not yet clinical trials to support this approach. Targeting the abnormal sources of increased oxidant stress that trigger abnormal pulmonary vascular responses may be more effective in treating disease and preventing long term consequences.

Oxygen for respiratory support of moderate and late preterm and term infants at birth: Is air best?

Oxygen has been used for newborn infant resuscitation for more than two centuries. In the last two decades, concerns about oxidative stress and injury have changed this practice. Air (FiO₂ 0.21) is now preferred as the starting point for respiratory support of infants 34 weeks gestation and above. These recommendations are derived from studies that were conducted on asphyxiated, term infants, recruited more than 10 years ago using strategies that are not commonly used today. The applicability of these recommendations to current practice, is uncertain. In addition, whether initiating respiratory support with air for infants with pulmonary disorders provides sufficient oxygenation is also unclear. This review will address these concerns and provide suggestions for future steps to address knowledge and practice gaps.

Placental Transfusion for Asphyxiated Infants

The current recommendation for umbilical cord management of non-vigorous infants (limp, pale, and not breathing) who need resuscitation at birth is to immediately clamp the umbilical cord. This recommendation is due in part to insufficient evidence for delayed cord clamping (DCC) or umbilical cord milking (UCM). These methods may provide a neuroprotective mechanism that also facilitates cardiovascular transition for non-vigorous infants at birth.

Optimal oxygenation and role of free radicals in PPHN

Effective ventilation of the lungs is essential in mediating pulmonary vasodilation at birth to allow effective gas exchange and an increase in systemic oxygenation. Unsuccessful transition prevents the increase in pulmonary blood flow after birth resulting in hypoxemia and persistent pulmonary hypertension of the newborn (PPHN). Management of neonates with PPHN includes ventilation of the lungs with supplemental oxygen to correct hypoxemia. Optimal oxygenation should meet oxygen demand to the tissues and avoid hypoxic pulmonary vasoconstriction (HPV) while preventing oxidative stress. The optimal target for oxygenation in PPHN is not known. Animal models have demonstrated that PaO₂<45 mmHg exacerbates HPV. However, there are no practical methods of assessing oxygen levels associated with oxidant stress. Oxidant stress can be due to free radical generation from underlying lung disease or from free radicals generated by supplemental oxygen. Free radicals act on the nitric oxide pathway reducing cGMP and promoting pulmonary vasoconstriction. Antioxidant therapy improves systemic oxygenation in an animal model of PPHN but there are no clinical trials to support such therapy. Targeting preductal SpO₂ between 90 and 97% and PaO₂ at 50-80 mmHg appears prudent in PPHN but clinical trials to support this practice are lacking. Preterm infants with PPHN present unique challenges due to lack of antioxidant defenses and functional and structural immaturity of the lungs. This review highlights the need for additional studies to mitigate the impact of oxidative stress in the lung and pulmonary vasculature in PPHN.