Association of Early Inhaled Nitric Oxide With the Survival of Preterm Neonates With Pulmonary Hypoplasia

Treating very preterm European infants with inhaled nitric oxide increased in-hospital mortality but did not affect neurodevelopment at 5 years of age

AIM

We examined the outcomes of using inhaled nitric oxide (iNO) to treat very preterm born (VPT) infants across Europe.

METHODS

This was a sub-study of the Screening to Improve Health in Very Preterm Infants in Europe research. It focused on all infants born between 22 + 0 and 31 + 6 weeks/days of gestation from 2011 to 2012, in 19 regions in 11 European countries. We studied 7268 infants admitted to neonatal care and 5 years later, we followed up the outcomes of 103 who had received iNO treatment. They were compared with 3502 propensity score-matched controls of the same age who did not receive treatment.

RESULTS

All countries used iNO and 292/7268 (4.0%) infants received this treatment, ranging from 1.2% in the UK to 10.5% in France. There were also large regional variations within some countries. Infants treated with iNO faced higher in-hospital mortality than matched controls (odds ratio 2.03, 95% confidence interval 1.33-3.09). The 5-year follow-up analysis of 103 survivors showed no increased risk of neurodevelopmental impairment after iNO treatment.

CONCLUSION

iNO was used for VPT patients in all 11 countries. In-hospital mortality was increased in infants treated with iNO, but long-term neurodevelopmental outcomes were not affected in 103 5-year-old survivors.

Challenges in clinical identification of right ventricular dysfunction in preterm infants with persistent pulmonary hypertension of the newborn

BACKGROUND

Right ventricular dysfunction, typically qualitatively diagnosed (Q-RVd) in preterm infants, requires echocardiography which is not always acutely available. We aimed to identify clinical indices of Q-RVd in very preterm infants (gestational age, GA <32 weeks) with persistent pulmonary hypertension of newborn (PPHN) and examine the reliability and validity of Q-RVd.

METHODS

Forty-seven infants with mean ± SD GA of 26.8 ± 2.7 weeks who had targeted neonatal echocardiography (TNE) ≤72 h old, during PPHN, were retrospectively studied. Three standard TNE clips were reviewed by two blinded assessors, and infants categorized as Q-RVd if moderate-severe RVd was diagnosed on ≥2 clips. Cardiopulmonary clinical indices at TNE and quantitative RV functional markers were compared between Q-RVd vs. no-RVd groups. Potential quantitative RVd definitions examined by classifying each measurement as "low" or "normal" using published data. Inter-rater agreement for Q-RVd assessed using Kappa statistics.

RESULTS

Mean age at TNE was 25.3 ± 20.4 h with Q-RVd diagnosed in 19(40 %) infants. Q-RVd group demonstrated higher peak oxygen requirements (96 ± 9 % vs. 84 ± 16 %, p < 0.01); however, no clinical parameters at TNE differentiated the groups. Quantitative measures were lower in Q-RVd patients, confirming classification validity. Among tested quantitative definitions, low RV stroke volume was associated with lower systolic blood pressure (41±7 vs. 47±9 mmHg, p = 0.02) and higher shock index (4.02±0.80 vs. 3.44±0.72, p = 0.02). Kappa for Q-RVd was 0.55 (95%CI 0.32-0.77).

CONCLUSIONS

The non-specific nature of clinical markers of RVd in preterm infants with PPHN necessitates echocardiographic diagnosis of RVd. Studies should examine prognostic relevance of RVd and establish outcome-based quantitative definitions in preterm infants.

Comorbidities and Late Outcomes in Neonatal Pulmonary Hypertension

Long-term outcomes of persistent pulmonary hypertension of newborn (PPHN) depend on disease severity, duration of ventilation, and associated anomalies. Congenital diaphragmatic hernia survivors may have respiratory morbidities and developmental delay. The presence of PPHN is associated with increased mortality in hypoxic-ischemic encephalopathy, though the effects on neurodevelopment are less clear. Preterm infants can develop pulmonary hypertension (PH) early in the postnatal course or later in the setting of bronchopulmonary dysplasia (BPD). BPD-PH is associated with higher mortality, particularly within the first year. Evidence suggests that both early and late PH in preterm infants are associated with neurodevelopmental impairment.

Early Pulmonary Hypertension in Preterm Infants

Pulmonary hypertension (PH) in preterm neonates has multifactorial pathogenesis with unique characteristics. Premature surfactant-deficient lungs are injured following exposure to positive pressure ventilation and high oxygen concentrations resulting in variable phenotypes of PH. The prevalence of early PH is variable and reported to be between 8% and 55% of extremely preterm infants. Disruption of the lung development and vascular signaling pathway could lead to abnormal pulmonary vascular transition. The management of early PH and the off-label use of selective pulmonary vasodilators continue to be controversial.

Neurodevelopmental outcomes of preterm neonates receiving rescue inhaled nitric oxide in the first week of age: a cohort study

OBJECTIVE

To assess the neurodevelopmental outcomes of preterm neonates who received inhaled nitric oxide (iNO) in the first week of age for hypoxaemic respiratory failure (HRF).

METHODS

In this retrospective cohort study, we included neonates born at <29 weeks gestational age (GA) between January 2010 and December 2018 who had a neurodevelopmental assessment at 18-24 months corrected age (CA) at one of the Canadian Neonatal Follow-Up Network clinics. The primary outcome was neurodevelopmental impairment (NDI). We performed propensity score-matched analysis to compare the outcomes of those who received and did not receive iNO.

RESULTS

Of the 5612 eligible neonates, 460 (8.2%) received iNO in the first week of age. Maternal age, receipt of antenatal corticosteroids, GA and birth weight were lower in the iNO group compared with the no-iNO group. Neonates in the iNO group had higher illness severity scores and higher rates of preterm prolonged rupture of membranes and were small for GA. Severe brain injury, bronchopulmonary dysplasia and mortality were higher in the iNO group. Of the 4889 survivors, 3754 (77%) neonates had follow-up data at 18-24 months CA. After propensity score matching, surviving infants who received rescue iNO were not associated with higher odds of NDI (adjusted OR 1.34; 95% CI 0.85 to 2.12).

CONCLUSIONS

In preterm neonates <29 weeks GA with HRF, rescue iNO use was not associated with worse neurodevelopmental outcomes among survivors who were assessed at 18-24 months CA.

Current and emerging pharmacotherapies for the treatment of pulmonary arterial hypertension in infants

INTRODUCTION

Pulmonary hypertension (PH) is a complex condition that encompasses an array of underlying disease processes and affects a diverse population of infants, including those with congenital heart disease, congenital diaphragmatic hernia, persistent PH of the newborn, and those with lung disease such as bronchopulmonary dysplasia. While there are treatments available to adults with PH, limited data exists for infants, especially for the newer medications. Therapies that target the three main pathophysiologic pathways of pulmonary hypertension appear to benefit infants, but which are best for each individual disease process is unclear.

AREAS COVERED

A review of the therapies to treat pulmonary hypertension is covered in this article including the prostacyclin pathway, endothelin pathway, and the nitric oxide pathway. Other adjunctive treatments are also discussed. Findings are based on a PubMed literature search of research papers spanning 1990-2023 and a search of ongoing trials registered with clinicaltrials.gov.

EXPERT OPINION

Overall therapies seem to improve outcomes with most infants with PH. However, given the diverse population of infants with PH, it is imperative to understand the basis for the PH in individual patients and understand which therapies can be applicable. Further research into tailored therapy for the specific populations is warranted.

Pulmonary Vascular Phenotypes of Prematurity: The Path to Precision Medicine

Pulmonary hypertension (PH) is associated with significant morbidities and high mortality in preterm infants, yet mechanisms contributing to the pathogenesis of PH, the impact of early pulmonary vascular disease (PVD) on the risk for BPD, the role for PH-targeted drug therapies, and long-term pulmonary vascular sequelae remain poorly understood. PVD is not a homogeneous disease, rather, PVD in the setting of prematurity includes various phenotypes as based on underlying pathophysiology, the severity of associated PH, the timing of disease onset, its contribution to hemodynamic and respiratory status, late outcomes, and other features. As with term newborns, severe hypoxemia with acute respiratory failure (HRF) in preterm infants can be due to marked elevation of pulmonary artery pressure with extrapulmonary shunt, traditionally referred to as persistent pulmonary hypertension of the newborn (PPHN). Transient and less severe levels of PH can also be observed during the early transition after birth without evidence of severe HRF, representing physiologic PH or delayed pulmonary vascular transition in preterm infants. Importantly, echocardiographic evidence of early PH has been strongly associated with the subsequent development of bronchopulmonary dysplasia (BPD), late PH, and chronic respiratory disease during infancy and early childhood. Late PH beyond the first postnatal months in preterm in neonates with established BPD is further associated with poor outcomes, especially as related to BPD severity. In addition, echocardiographic signs of PVD can further persist throughout childhood and may lead to chronic PH of variable severity and cardiac maldevelopment in prematurely born young adults. This review discusses the importance of characterizing diverse pulmonary vascular phenotypes in preterm infants to better guide clinical care and research, and to enhance the development of more precise therapeutic strategies to optimize early and late outcomes of preterm infants.

L'utilisation du monoxyde d'azote inhalé chez les nouveau-nés

Le monoxyde d'azote inhalé (NOi), un vasodilatateur pulmonaire sélectif, est utilisé pour le traitement des nouveau-nés en insuffisance respiratoire hypoxémique (IRH) associée à une hypertension pulmonaire persistante du nouveau-né. Idéalement, il doit commencer à être administré après la confirmation échocardiographique de ce type d'hypertension. L'utilisation de NOi est recommandée chez les nouveau-nés peu prématurés ou à terme chez qui survient une IRH malgré des stratégies d'oxygénation ou de ventilation optimales. Cependant, il n'est pas recommandé d'y recourir systématiquement chez les nouveau-nés prématurés sous assistance respiratoire. On peut l'envisager comme traitement de secours chez les nouveau-nés prématurés en IRH précoce associée à une rupture prolongée des membranes ou à un oligoamnios, ou en IRH tardive en cas d'hypertension pulmonaire liée à une dysplasie bronchopulmonaire et accompagnée d'une insuffisance ventriculaire droite marquée. On peut aussi l'envisager chez les nouveau-nés atteints d'une hernie diaphragmatique congénitale qui présentent une IRH persistante, malgré un recrutement pulmonaire optimal, des signes échocardiographiques d'hypertension pulmonaire suprasystémique et un fonctionnement ventriculaire gauche approprié.

Inhaled nitric oxide use in newborns

Inhaled nitric oxide (iNO), a selective pulmonary vasodilator, is used as a therapeutic modality in infants with hypoxemic respiratory failure (HRF) associated with persistent pulmonary hypertension of the newborn (PPHN). iNO should ideally be initiated following echocardiographic confirmation of PPHN. Use of iNO is recommended in late preterm and term infants who develop HRF despite optimal oxygenation and ventilation strategies. However, routine iNO use in preterm infants on respiratory support is not recommended. iNO may be considered as a rescue modality in preterm infants with early-onset HRF when associated with prolonged rupture of membranes or oligohydramnios, or late-onset HRF in the context of bronchopulmonary dysplasia-associated pulmonary hypertension (PH) with severe right ventricular failure. A trial of iNO may also be considered for infants with congenital diaphragmatic hernia with persistent HRF despite optimal lung recruitment, and with echocardiographic evidence of supra-systemic PH and adequate left ventricular function.

Inhaled nitric oxide in preterm neonates with preterm prelabour rupture of membranes, a systematic review

AIM

To perform a systematic literature review to determine the effect of inhaled nitric oxide (iNO) on oxygenation, mortality and morbidity in preterm neonates with preterm prelabour rupture of membranes (PPROM) and early hypoxaemic respiratory failure (HRF).

METHODS

MEDLINE, Embase, Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, Web of Science, Zetoc and ProQuest were searched. Studies including neonates <34 weeks' gestation with PPROM, oligohydramnios or pulmonary hypoplasia and HRF in the first 28 days of life treated with iNO were included. Studies were critically appraised and assessed for potential risk of bias using standardised checklists.

RESULTS

Six hundred and two records remained after duplicates were removed. Seven studies were included in the critical appraisal process. Quality of available evidence was very low to low. Six studies described an improvement in oxygenation after commencement of iNO. One hundred and three of 284 (36%) neonates exposed to iNO died. Seventy-seven of 92 (84%) neonates that had an echocardiogram performed before commencement of iNO had pulmonary hypertension (PH) present.

CONCLUSION

iNO may improve oxygenation when standard care fails. Improvement in oxygenation is likely associated with increase in survival. Survival may lead to an increase in morbidity. Efficacy of iNO in this cohort is likely secondary to relatively high prevalence of PH.

Efficacy of perinatal pharmacotherapeutic actions for survival of very preterm newborn rabbits at 26-day gestation

Investigation of the pathophysiology of lung impairment and protection in very preterm neonates at birth requires adequate experimental models. This study aimed to elucidate the efficacy and mechanism of perinatal pharmacotherapeutic action in postnatal survival of very preterm rabbits. Pregnant New Zealand White rabbits on 25-day gestation (term 31 days) were given dexamethasone (D), or sham injection as control (C), and cesarean delivered 24 hours later on day 26. Newborns were anesthetized, intratracheally intubated, randomly received either saline or porcine surfactant (S), allocated to four groups (C, S, D, and DS), and ventilated with low tidal volume. Under the identical protocol, another four groups were added with nitric oxide (N) inhalation (CN, SN, DN, and DSN). Survival length, lung mechanics, histopathology, and pathobiology of lung tissue were measured for benefits and injury patterns. DSN had the longest median survival time (ST50, 10.3 h), whereas C had the shortest (3.5 h), with remaining groups in-between. The survival was mainly benefited by S, when additive effects with D and/or N were discernible, by improved lung mechanics and alveolar aeration, ameliorated lung injury severity and pneumothorax, and augmented lung phospholipid pools, with DSN being the most optimal. Variable mRNA expression profiles of alveolar epithelia-associated cytokines and inflammatory mediators further characterized injury and response patterns as phenotyping conditioned in pharmacotherapeutic actions. In conclusion, the combined regimens of perinatal medications achieved remarkable survival in very preterm rabbits with lung protective ventilation strategy, offering a unique model in investigation of very preterm birth-associated respiratory physiology and morbidities.NEW & NOTEWORTHY By establishing a very preterm rabbit model with 26-day gestation (term 31 days), optimal survival length for 50% of animals in groups was achieved by comparing regimens of combined antenatal glucocorticoids, postnatal surfactant and inhaled nitric oxide, with a low tidal volume ventilation strategy. The efficacies of pharmacotherapeutic action were associated with significantly improved lung mechanics, ameliorated lung injury and pneumothorax, and enhanced surfactant phospholipid metabolism, along with variable mRNA expression profiles characterizing the response patterns.

MXene-Derived Metal-Organic Framework@MXene Heterostructures toward Electrochemical NO Sensing

The electrochemical sensing of nitric oxide (NO) molecules by metal-organic framework (MOF) catalysts has been impeded, to a large extent, owing to their poor electrical conductivity and weak NO adsorption. In this work, incomplete in situ conversion of V₂ CT_x (T = terminal atoms) MXene to MOF is adopted, forming MOF@MXene heterostructures, which outperform MXene and MOF monocomponents toward electrochemical NO sensing. Density functional theory (DFT) calculation results indicate metal-like electronic characters for the heterostructure benefiting from the dominating contribution of the V 3d orbitals of the metallic MXene. Moreover, plane-averaged charge density difference shows substantial charge redistribution occurs at the heterointerfaces, producing a built-in field, which facilitates charge transfer. Besides, molecular mechanics-based simulated annealing calculation reveals greatly enhanced adsorption energies of NO molecules on the heterointerfaces than that on separate MOFs and MXenes. Hence, the facilitated charge transfer and preferential NO adsorption are responsible for the dramatically promoted performance toward NO sensing. The prudent design of MOF@MXene heterostructure may spur advanced electrocatalysts for electrochemical sensing.

Clinical burden associated with therapies for cardio-pulmonary critical decompensation in preterm neonates across Canadian neonatal intensive care units

The aim of this retrospective cohort study was to study the clinical burden associated with cardio-pulmonary critical decompensations (CPCDs) in preterm neonates and factors associated with mortality. Through the Canadian Neonatal Network (30 tertiary NICUs, 2010-2017), we identified infants < 32-week gestational age with CPCDs, defined by "significant exposure" to cardiotropes and/or inhaled nitric oxide (iNO): (1) either therapy for ≥ 3 consecutive days, (2) both for ≥ 2 consecutive days, or (3) any exposure within 2 days of death. Early CPCDs (≤ 3 days of age) and late CPCDs (> 3 days) were examined separately. Outcomes included CPCD-incidence, mortality, and inter-site variability using standardized ratios (observed/adjusted expected rate) and network funnel plots. Mixed-effects analysis was used to quantify unit-level variability in mortality. Overall, 10% of admissions experienced CPCDs (n = 2915). Late CPCDs decreased by ~ 5%/year, while early CPCDs were unchanged during the study period. Incidence and CPCD-associated mortality varied between sites, for both early (0.6-7.5% and 0-100%, respectively) and late CPCDs (2.5-15% and 14-83%, respectively), all p < 0.01. Units' late-CPCD incidence and mortality demonstrated an inverse relationship (slope =  -2.5, p < 0.01). Mixed-effects analysis demonstrated clustering effect, with 6.4% and 8.6% of variability in mortality after early and late CPCDs respectively being site-related, unexplained by available patient-level characteristics or unit volume. Mortality was higher with combined exposure than with only-cardiotropes or only-iNO (41.3%, 24.8%, 21.5%, respectively; p < 0.01).

CONCLUSIONS

Clustering effects exist in CPCD-associated mortality among Canadian NICUs, with higher incidence units showing lower mortality. These data may aid network-level benchmarking, patient-level risk stratification, parental counseling, and further research and quality improvement work.

WHAT IS KNOWN

• Preterm neonates remain at high risk of acute and chronic complications; the most critically unwell require therapies such as cardiotropic drugs and inhaled nitric oxide. • Infants requiring these therapies are known to be at high risk for adverse neonatal outcomes and for mortality.

WHAT IS NEW

• This study helps illuminate the national burden of acute cardio-pulmonary critical decompensation (CPCD), defined as the need for cardiotropic drugs or inhaled nitric oxide, and highlights the high risk of morbidity and mortality associated with this disease state. • Significant nationwide variability exists in both CPCD incidence and associated mortality; a clustering effect was observed with higher incidence sites showing lower CPCD-associated mortality.

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.

The Controversy Persists: Is There a Qualification Criterion to Utilize Inhaled Nitric Oxide in Pre-term Newborns?

Inhaled nitric oxide (iNO) use in premature newborns remains controversial among clinicians. In 2014, the American Academy of Pediatrics, Committee on Fetus and Newborn released a statement that the available data do not support routine iNO use in pre-term newborns. Despite the absence of significant benefits, 2016 California data showed that clinicians continue to utilize iNO in pre-term infants. With studies as recent as January 2017, the Cochrane review confirmed no major advantages of iNO in pre-term newborns. Still, it recognized that a subset of pre-term infants with pulmonary hypertension (PHTN) had not been separately investigated. Furthermore, recent non-randomized controlled trials have suggested that iNO may benefit specific subgroups of pre-term newborns, especially those with PHTN, prolonged rupture of membranes, and antenatal steroid exposure. Those pre-term infants who showed a clinical response to iNO had increased survival without disability. These findings underscore the need for future studies in pre-term newborns with hypoxemic respiratory failure and PHTN. This review will discuss the rationale for using iNO, controversies regarding the diagnosis of PHTN, and additional novel approaches of iNO treatment in perinatal asphyxia and neonatal resuscitation in the pre-term population < 34 weeks gestation.

Pulmonary Hypertension: The Hidden Danger for Newborns

Despite growing awareness of the clinical importance of pulmonary hypertension (PH) in preterm infants, uncertainty persists regarding the different clinical settings in which abnormalities of pulmonary vascular growth, function, and structure contribute to high morbidity and mortality, and potential interventions to improve outcomes are uncertain. A major gap for improving outcomes of preterm infants with PH has been the limited characterization of the distinct settings of PH and related disease-specific mechanisms in preterm infants that represent diverse pulmonary vascular phenotypes of prematurity. In comparison with term newborns, preterm infants have a higher risk for developing hypoxemia due to suprasystemic levels of PH in preterm infants shortly after birth or persistent pulmonary hypertension of the newborn (PPHN). Variable and milder levels of PH have also been demonstrated in preterm infants without evidence of severe hypoxemic respiratory failure, suggesting delayed vascular transition of the lung which is associated with higher risks of mortality and developing bronchopulmonary dysplasia (BPD). In addition, early echocardiographic signs of PH at day 7 are strongly associated with the subsequent diagnosis of BPD, late PH, and respiratory disease throughout early childhood. In infants with evolving or established BPD, PH that persists beyond the first few months of life in preterm infants is associated with high mortality. Recent data further show that PVD can persist and cause PH in prematurely born adults. Overall, more precise characterization and studies of diverse pulmonary vascular phenotypes in preterm infants will be likely to improve the development of therapeutic strategies to optimize care of preterm infants with PH.

Early Hypoxic Respiratory Failure in Extreme Prematurity: Mortality and Neurodevelopmental Outcomes

OBJECTIVES

To evaluate the survival and neurodevelopmental impairment (NDI) in extremely low birth weight (ELBW) infants at 18 to 26 months with early hypoxemic respiratory failure (HRF). We also assessed whether African American infants with early HRF had improved outcomes after exposure to inhaled nitric oxide (iNO).

METHODS

ELBW infants ≤1000 g and gestational age ≤26 weeks with maximal oxygen ≥60% on either day 1 or day 3 were labeled as "early HRF" and born between 2007 and 2015 in the Neonatal Research Network were included. Using a propensity score regression model, we analyzed outcomes and effects of exposure to iNO overall and separately by race.

RESULTS

Among 7639 ELBW infants born ≤26 weeks, 22.7% had early HRF. Early HRF was associated with a mortality of 51.3%. The incidence of moderate-severe NDI among survivors was 41.2% at 18 to 26 months. Mortality among infants treated with iNO was 59.4%. Female sex (adjusted odds ratio [aOR]: 2.4, 95% confidence interval [CI]: 1.8-3.3), birth weight ≥720 g (aOR: 2.3, 95% CI: 1.7-3.1) and complete course of antenatal steroids (aOR: 1.6, 95% CI: 1.1-2.2) were associated with intact survival. African American infants had a similar incidence of early HRF (21.7% vs 23.3%) but lower exposure to iNO (16.4% vs 21.6%). Among infants with HRF exposed to iNO, intact survival (no death or NDI) was not significantly different between African American and other races (aOR: 1.5, 95% CI: 0.6-3.6).

CONCLUSIONS

Early HRF in infants ≤26 weeks' gestation is associated with high mortality and NDI at 18 to 26 months. Use of iNO did not decrease mortality or NDI. Outcomes following iNO exposure were not different in African American infants.

Inhaled nitric oxide use in neonates: Balancing what is evidence-based and what is physiologically sound

Inhaled nitric oxide is a powerful therapeutic used in neonatology. Its use is evidenced-based for term and near-term infants with persistent pulmonary hypertension; however, it is frequently used off-label both in term and preterm babies. This article reviews the off-label uses of iNO in infants. Rationale is discussed for a selective application of iNO based on physiologically guided principles, and new research avenues are considered.

Mitochondrial Dysfunction: Metabolic Drivers of Pulmonary Hypertension

Significance: Pulmonary hypertension (PH) is a progressive disease characterized by pulmonary vascular remodeling and lung vasculopathy. The disease displays progressive dyspnea, pulmonary artery uncoupling and right ventricular (RV) dysfunction. The overall survival rate is ranging from 28-72%. Recent Advances: The molecular events that promote the development of PH are complex and incompletely understood. Metabolic impairment has been proposed to contribute to the pathophysiology of PH with evidence for mitochondrial dysfunction involving the electron transport chain proteins, antioxidant enzymes, apoptosis regulators, and mitochondrial quality control. Critical Issues: It is vital to characterize the mechanisms by which mitochondrial dysfunction contribute to PH pathogenesis. This review focuses on the currently available publications that supports mitochondrial mechanisms in PH pathophysiology. Future Directions: Further studies of these metabolic mitochondrial alterations in PH could be viable targets of diagnostic and therapeutic intervention.

Drugs for the Prevention and Treatment of Bronchopulmonary Dysplasia

Rates of bronchopulmonary dysplasia (BPD) are increasing. After preterm birth, there are important developmental periods in which neonates are more vulnerable to stressful events. These periods are opportunities for pharmacologic interventions. Many drugs remain inadequately tested and no new drugs have been approved in more than 25 years for BPD prevention or therapy. More progress is needed in defining appropriate end points based on the pathophysiology of BPD and postdischarge chronic pulmonary insufficiency of prematurity and to develop effective new drugs. In addition, much work is needed to better define perinatal factors, early postnatal findings, and physiologic phenotypes or endotypes.

Nitric Oxide in Pulmonary Hypoplasia: Results from the European iNO Registry

OBJECTIVES

The aim of this work was to describe treatment response and outcome data for preterm infants with pulmonary hypoplasia treated with inhaled nitric oxide (iNO). We hypothesised that an acute oxygenation response to iNO would be associated with survival.

DESIGN

A retrospective observational study design was used to identify cases of pulmonary hypoplasia in preterm infants <34 weeks' gestation reported to the European iNO Registry. Demographic and clinical data were collected including oxygenation and echocardiographic parameters. The primary outcome was acute oxygenation response defined as a reduction in fractional inspired oxygen of >0.15. Outcome data included chronic lung disease (CLD) and death.

RESULTS

Seventy-two infants with pulmonary hypoplasia were treated with iNO during a 10-year period (2007-2016). In total, 30/69 (43%) of the infants showed a significant improvement in oxygenation and were categorised as "responders." Thirty-one treated infants died, and 19 survivors developed CLD. Although there were no differences in demographics and baseline cardiorespiratory parameters between responders and non-responders, an acute response was significantly associated with survival. Neither pulmonary hypertension nor PPHN (persistent pulmonary hypertension of the newborn) physiology predicted the acute response to iNO or survival.

CONCLUSION

Although the acute oxygenation response to iNO therapy in pulmonary hypoplasia is comparable to other respiratory disorders in preterm infants, mortality in this group remains very high. An acute response is associated with survival and suggests that a short therapeutic trial of iNO therapy is warranted in this population. This study underscores the value of registries in evaluating therapies for rare neonatal disorders, although their limitations must be recognised.

Factors influencing decision making in neonatology: inhaled nitric oxide in preterm infants

OBJECTIVE

We studied decision making regarding inhaled nitric oxide (iNO) in preterm infants with Pulmonary Hypertension (PH).

STUDY DESIGN

We asked members of the AAP-Society of Neonatal-Perinatal Medicine and Division-Chiefs to select from three management options- initiate iNO, engage parents in shared decision making or not consider iNO in an extremely preterm with PH followed by rating of factors influencing their decision.

RESULTS

Three hundred and four respondents (9%) completed the survey; 36.5% chose to initiate iNO, 42% to engage parents, and 21.5% did not consider iNO. Provider's prior experience, safety, and patient-centered care were rated higher by those who initiated or offered iNO; lack of effectiveness and cost considerations by participants who did not chose iNO.

CONCLUSIONS

Most neonatologists offer or initiate iNO therapy based on their individual experience. The minority who chose not to consider iNO placed higher value on lack of effectiveness and cost. These results demonstrate a tension between evidence and pathophysiology-based-therapy/personal experience.

European Consensus Guidelines on the Management of Respiratory Distress Syndrome - 2019 Update

As management of respiratory distress syndrome (RDS) advances, clinicians must continually revise their current practice. We report the fourth update of "European Guidelines for the Management of RDS" by a European panel of experienced neonatologists and an expert perinatal obstetrician based on available literature up to the end of 2018. Optimising outcome for babies with RDS includes prediction of risk of preterm delivery, need for appropriate maternal transfer to a perinatal centre and timely use of antenatal steroids. Delivery room management has become more evidence-based, and protocols for lung protection including initiation of CPAP and titration of oxygen should be implemented immediately after birth. Surfactant replacement therapy is a crucial part of management of RDS, and newer protocols for its use recommend early administration and avoidance of mechanical ventilation. Methods of maintaining babies on non-invasive respiratory support have been further developed and may cause less distress and reduce chronic lung disease. As technology for delivering mechanical ventilation improves, the risk of causing lung injury should decrease, although minimising time spent on mechanical ventilation using caffeine and, if necessary, postnatal steroids are also important considerations. Protocols for optimising general care of infants with RDS are also essential with good temperature control, careful fluid and nutritional management, maintenance of perfusion and judicious use of antibiotics all being important determinants of best outcome.