Inhaled nitric oxide in preterm infants: an individual-patient data meta-analysis of randomized trials

Strategies for the prevention of bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is a common morbidity affecting preterm infants and is associated with substantial long-term disabilities. The pathogenesis of BPD is multifactorial, and the clinical phenotype is variable. Extensive research has improved the current understanding of the factors contributing to BPD pathogenesis. However, effectively preventing and managing BPD remains a challenge. This review aims to provide an overview of the current evidence regarding the prevention of BPD in preterm infants, offering practical insights for clinicians.

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.

Association between immediate oxygenation response and survival in preterm infants receiving rescue inhaled nitric oxide therapy for hypoxemia from pulmonary hypertension: A systematic review and meta-analysis

PURPOSE

To investigate whether immediate response to inhaled nitric oxide (iNO) therapy is associated with reduced mortality in preterm infants with hypoxemic respiratory failure (HRF) and pulmonary hypertension (PH).

METHODS

A systematic review and meta-analysis of observational studies was conducted to examine the association between immediate response (improved oxygenation ≤6 h) compared to non-response, and all-cause mortality among preterm infants <34 weeks gestational age without congenital anomalies or genetic disorders who received iNO treatment. Adjusted and unadjusted odds ratio, were pooled using a random effects meta-analysis Hartung-Knapp-Sidik-Jonkman approach. Subgroup analyses were planned for infants with preterm premature rupture of membranes (PPROM) and those treated within 72 h after birth.

RESULTS

The primary analysis included 5 eligible studies, a total of 400 infants (196 responders; 204 non-responders). The studies were rated as low to moderate risk of bias based on the Quality in Prognostic Studies tool. Immediate iNO responsiveness was associated with reduced odds of mortality [odds ratio (OR) 0.22, 95 % confidence interval (95 % CI) (0.10-0.49)]. Although there was insufficient data for a subgroup analysis of infants with PPROM, infants treated with iNO within 72 h demonstrated consistent findings of reduced mortality [OR 0.21 95 % CI (0.13-0.36)]. Based on the GRADE approach, considering the risk of bias of included studies, the overall strength of evidence was rated as moderate.

CONCLUSION

There is evidence to suggest that immediate improvement in oxygenation following iNO therapy is associated with reduced odds of mortality before discharge in preterm infants with HRF and clinically suspected or confirmed PH.

Inhaled nitric oxide in premature infants for preventing bronchopulmonary dysplasia: a meta-analysis

BACKGROUND

The effectiveness of nitric oxide (NO) in reducing the risk of bronchopulmonary dysplasia (BPD) remains debatable. In this study, we performed a meta-analysis to guide clinical decision-making regarding the significance of inhaled NO (iNO) on the potential occurrence and outcomes of BPD in premature infants.

METHODS

Data from clinical randomized controlled trials (RCTs) published in PubMed, Embase, Cochrane Library, Wanfang, China National Knowledge Infrastructure (CNKI) and Chinese Scientific Journal Database VIP databases for premature infants were searched from inception to March 2022. Review Manager 5.3 statistical software was used for heterogeneity analysis.

RESULTS

Of the 905 studies retrieved, 11 RCTs met the screening criteria of this study. Our analysis showed that the iNO group was associated with a significantly lower incidence of BPD than the control group (relative risk [RR] = 0.91, 95% confidence interval (CI) 0.85-0.97, P = 0.006). We also observed no significant difference in the incidence of BPD between the two groups at the initial dose of 5 ppm (ppm) (P = 0.09) but those treated with 10 ppm iNO had a significantly lower incidence of BPD (RR = 0.90, 95%CI 0.81-0.99, P = 0.03). However, it should be noted that although the iNO group had an increased risk for necrotizing enterocolitis (NEC) (RR = 1.33, 95%CI 1.04-1.71, P = 0.03), cases treated with an initial dose of 10 ppm revealed no significant difference in the incidence of NEC compared with the control group (P = 0.41), while those treated with an initial dosage of 5 ppm of iNO had a significantly greater NEC rates than the control group (RR = 1.41, 95%CI 1.03-1.91, P = 0.03). Further, we observed no statistically significant differences in the incidence of in-hospital mortality, intraventricular hemorrhage (IVH) (Grade 3/4) or periventricular leukomalacia (PVL) and pulmonary hemorrhage (PH) between the two treatment groups.

CONCLUSIONS

This meta-analysis of RCTs showed that iNO at an initial dosage of 10 ppm seemed more effective in reducing the risk of BPD than conventional treatment and iNO at an initial dosage of 5 ppm in preterm infants at a gestational age of ≤34 weeks who required respiratory support. However, the incidence of in-hospital mortality and adverse events between the overall iNO group and Control were similar.

Therapeutic response of iNO in preterm infants with hypoxemic respiratory failure

BACKGROUND

Inhaled nitric oxide (iNO) has been used as a rescue treatment for preterm infants with hypoxemic respiratory failure (HRF). However, its effectiveness remains debatable. Thus, in this study, we aimed to examine the impact of iNO therapy on HRF in extremely preterm infants.

METHODS

A retrospective observational study was performed. Extremely preterm infants admitted to our neonatal intensive care unit who received iNO therapy later in their postnatal life were included. The oxygen saturation index (OSI) was used as an index of the severity of respiratory failure.

RESULTS

In total, 30 extremely preterm infants were included in this study. Oxygenation was enhanced after the administration of iNO in infants with HRF. The OSI decreased by more than 20% in 12 patients (40%, positive responder) and did not decrease in 17 patients (57%, negative responder) within the first 6 h of treatment. The iNO initiation day was the significant independent factor associated with a positive response to iNO therapy in extremely preterm infants with HRF.

CONCLUSIONS

iNO therapy was effective in enhancing oxygenation in extremely preterm infants with HRF. Earlier use of iNO was the significant factor associated with a positive therapeutic response to iNO, implying that iNO may be more effective in pulmonary vessels which are less damaged by shorter-term mechanical ventilation.

Inhaled Nitric Oxide Therapy in the Post-Acute Phase in Extremely Preterm Infants: A Japanese Cohort Study

OBJECTIVE

To determine the trends in inhaled nitric oxide (iNO) utilization in the late phase of hospitalization in a large Japanese cohort of extremely preterm infants and evaluate its benefit on long-term outcomes.

STUDY DESIGN

This was a retrospective multicenter cohort study of 15 977 extremely preterm infants born at <28 weeks of gestational age between 2003 and 2016, in the Neonatal Research Network, Japan. Demographic characteristics, morbidity, and mortality were compared between extremely preterm infants with and without post-acute iNO therapy. Multivariable logistic analysis was performed to determine factors associated with post-acute iNO and its impact on neurodevelopmental outcomes at 3 years of age.

RESULTS

Post-acute iNO utilization rates increased from 0.3% in 2009 to 1.9% in 2016, even under strict insurance coverage rules starting in 2009. Gestational age (1-week increment; aOR 0.82, 95% CI 0.76-0.88), small for gestational age (1.47, 1.08-1.99), histologic chorioamnionitis (1.50, 1.21-1.86), 5-minute Apgar score <4 (1.51, 1.10-2.07), air leak (1.92, 1.30-2.83), and bubbly/cystic appearance on chest X-Ray (1.68, 1.37-2.06) were associated with post-acute iNO. Post-acute iNO was not associated with neurodevelopmental outcomes at 3 years of age.

CONCLUSIONS

The increasing post-acute iNO utilization rate among extremely preterm infants has been concurrent with improved survival rates of extremely preterm infants in Japan. Infants treated with post-acute iNO had more severe disease and complications than the comparison group, but there were no differences in neurodevelopmental outcome at 3 years. This suggests post-acute iNO may benefit extremely preterm infants.

How to diagnose and treat acute pulmonary hypertension when you have no cardiology support

Acute pulmonary hypertension (aPH) is a complex, physiology-driven disorder that causes critical illness in newborns, the hallmark of which is elevated pressure in the pulmonary vascular bed. Several underlying hemodynamic phenotypes exist, including classic arterial aPH with resistance-driven elevations in pulmonary arterial pressure (PAP), alongside flow-driven aPH from left-to-right shunt lesions, and primary left ventricular dysfunction with pulmonary venous hypertension and elevated left atrial pressure. Targeted neonatal echocardiography (TnECHO) is an important tool for evaluation of hemodynamics in aPH and is highly useful for evaluating modulators of disease and targeting cardiovascular therapy. The diagnostic approach to aPH includes confirmation of elevation of PAP, evaluation of the cause and exclusion of structural cardiac disease, assessment of the response of the myocardium to adverse loading conditions, and appraisal of the adequacy of systemic blood flow. Therapeutic goals include support of right ventricular (RV) function, RV afterload reduction, and selection of cardiotropic agents that support underlying pathophysiology without adverse effects on heart rate or pulmonary vascular resistance in addition to routine supportive intensive care. Training programs for TnECHO exist across multiple jurisdictions and strong correlation with pediatric cardiology assessment has been demonstrated. Future directions include adapting TnECHO training with a greater focus on achieving competency, and further research into the role of the modality in providing individualized cardiovascular care for patients with heterogenous underlying physiology, and its effect on key neonatal outcomes.

Pulmonary vasodilator strategies in neonates with acute hypoxemic respiratory failure and pulmonary hypertension

The management of acute hypoxemic respiratory failure (AHRF) in newborns continues to be a clinical challenge with elevated risk for significant morbidities and mortality, especially when accompanied with persistent pulmonary hypertension of the newborn (PPHN). PPHN is a syndrome characterized by marked hypoxemia secondary to extrapulmonary right-to-left shunting across the ductus arteriosus and/or foramen ovale with high pulmonary artery pressure and increased pulmonary vascular resistance (PVR). After optimizing respiratory support, cardiac performance and systemic hemodynamics, targeting persistent elevations in PVR with inhaled nitric oxide (iNO) therapy has improved outcomes of neonates with PPHN physiology. Despite aggressive cardiopulmonary management, a significant proportion of patients have an inadequate response to iNO therapy, prompting consideration for additional pulmonary vasodilator therapy. This article reviews the pathophysiology and management of PPHN in term newborns with AHRF while highlighting both animal and human data to inform a physiologic approach to the use of PH-targeted therapies.

Use of Inhaled Nitric Oxide in Preterm Infants: Is There Sufficient Evidence?

Nitric oxide (NO) is a potent vasodilator. The inhaled form (iNO) improves outcomes in term infants with persistent pulmonary hypertension of the newborn (PPHN) or bronchopulmonary dysplasia-associated pulmonary hypertension in preterm infants. However, in preterm infants, the risks and benefits of iNO use are controversial. Substantial evidence reveals no significant impact on survival or other morbidities in preterm infants with iNO treatment, independent of indication, timing, or duration of use. Many scientific organizations do not recommend the use of iNO in preterm infants, except in unique clinical circumstances with echocardiographic findings of PPHN in the setting of presumed pulmonary hypoplasia.

Epidemiologic evaluation of inhaled nitric oxide use among neonates with gestational age less than 35 weeks

BACKGROUND AND OBJECTIVES

The use of inhaled nitric oxide (iNO) in +late preterm and term infants with pulmonary hypertension is Food and Drug Administration (FDA) approved and has improved outcomes and survival. iNO use is not FDA approved for preterm infants and previous studies show no mortality benefit. The objectives were 1) to determine the usage of iNO among preterm neonates <35 weeks before and after the 2010 National Institutes of Health consensus statement and 2) to evaluate characteristics and outcomes among preterm neonates who received iNO.

METHODS

This is a population-based cross-sectional study. Billing and procedure codes were used to determine iNO usage. Data were queried from the National Inpatient Sample from 2004 to 2016. Neonates were included if gestational age was <35 weeks. The epochs were spilt into 2004-2010 (Epoch 1) and 2011-2016 (Epoch 2). Prevalence of iNO use, mortality, bronchopulmonary dysplasia (BPD), intraventricular hemorrhage, length of stay, mechanical ventilation, and cost of hospitalization.

RESULTS

There were 4865 preterm neonates <35 weeks who received iNO. There was a significant increase in iNO use during Epoch 2 (p < 0.001). There was significantly higher use in Epoch 2 among neonates small for gestational age (SGA) 2.3% versus 7.2%, congenital heart disease (CHD) 11.1% versus 18.6%, and BPD 35.2% versus 46.8%. Mortality was significantly lower in Epoch 2 19.8% versus 22.7%.

CONCLUSION

Usage of iNO was higher after the release of the consensus statement. The increased use of iNO among preterm neonates may be targeted at specific high-risk populations such as SGA and CHD neonates. There was lower mortality in Epoch 2; however, the cost was doubled.

Impact of early respiratory care for extremely preterm infants

Despite advances in neonatal intensive care, more than half of surviving infants born extremely preterm (EP; < 28 weeks' gestation) develop bronchopulmonary dysplasia (BPD). Prevention of BPD is critical because of its associated mortality and morbidity, including adverse neurodevelopmental outcomes and respiratory health in later childhood and beyond. The respiratory care of EP infants begins before birth, then continues in the delivery room and throughout the primary hospitalization. This chapter will review the evidence for interventions after birth that might improve outcomes for infants born EP, including the timing of umbilical cord clamping, strategies to avoid or minimize exposure to mechanical ventilation, modes of mechanical ventilation and non-invasive respiratory support, oxygen saturation targets, postnatal corticosteroids and other adjunct therapies.

Bronchopulmonary dysplasia-A historical perspective

Bronchopulmonary dysplasia (BPD) was first described by Northway et al in 1967. This article describes the evolution of our understanding of the pathophysiology of BPD and the approaches to treatments of this illness developed over the past fifty years. These interventions had their roots in the understanding of the principles of the surface tension present at air-liquid interfaces, which were developed over 150 years before BPD's initial description. Improving outcomes in neonatal care have led to greater survival of preterm and very preterm infants, and to an evolution of the pathogenesis and pathology of BPD, from an illness caused primarily by barotrauma and oxygen toxicity to one of interruption of lung development. While the incidence of BPD has remained about the same in recent decades, this is because survival of infants born at lower gestational ages is increasing. Understanding of molecular, genetic and physiologic mechanisms has led to newer treatments that have mitigated some of the harmful effects of prolonged mechanical ventilation. Recognition of BPD as a chronic multi-system disease has resulted in further improvements in care after discharge from neonatal intensive care. Since many of the origins of chronic obstructive lung disease in adults are based in childhood respiratory illnesses, improving outcomes of BPD in infancy and childhood will undoubtedly lead to improved respiratory outcomes in the adults that these children will become.

Evidence for the Management of Bronchopulmonary Dysplasia in Very Preterm Infants

BACKGROUND

Very preterm birth often results in the development of bronchopulmonary dysplasia (BPD) with an inverse correlation of gestational age and birthweight. This very preterm population is especially exposed to interventions, which affect the development of BPD.

OBJECTIVE

The goal of our review is to summarize the evidence on these daily procedures and provide evidence-based recommendations for the management of BPD.

METHODS

We conducted a systematic literature research using MEDLINE/PubMed on antenatal corticosteroids, surfactant-replacement therapy, caffeine, ventilation strategies, postnatal corticosteroids, inhaled nitric oxide, inhaled bronchodilators, macrolides, patent ductus arteriosus, fluid management, vitamin A, treatment of pulmonary hypertension and stem cell therapy.

RESULTS

Evidence provided by meta-analyses, systematic reviews, randomized controlled trials (RCTs) and large observational studies are summarized as a narrative review.

DISCUSSION

There is strong evidence for the use of antenatal corticosteroids, surfactant-replacement therapy, especially in combination with noninvasive ventilation strategies, caffeine and lung-protective ventilation strategies. A more differentiated approach has to be applied to corticosteroid treatment, the management of patent ductus arteriosus (PDA), fluid-intake and vitamin A supplementation, as well as the treatment of BPD-associated pulmonary hypertension. There is no evidence for the routine use of inhaled bronchodilators and prophylactic inhaled nitric oxide. Stem cell therapy is promising, but should be used in RCTs only.

BPD treatments: The never-ending smorgasbord

Despite important advances in neonatal care, rates of bronchopulmonary dysplasia (BPD) have remained persistently high. Numerous drugs and ventilator strategies are used for the prevention and treatment of BPD. Some, such as exogenous surfactant, volume targeted ventilation, caffeine, and non-invasive respiratory support, are associated with modest but important reductions in rates of BPD and long-term respiratory morbidities. Many other therapies, such as corticosteroids, diuretics, nitric oxide, bronchodilators and anti-reflux medications, are widely used despite conflicting, limited or no evidence of efficacy and safety. This paper examines the range of therapies used for the prevention or treatment of BPD. They are classified into those supported by evidence of effectiveness, and those which are widely used despite limited evidence or unclear risk to benefit ratios. Finally, the paper explores emerging therapies and approaches which aim to prevent or reduce BPD and long-term respiratory morbidity.

Persistent pulmonary hypertension of the newborn

Persistent pulmonary hypertension of the newborn (PPHN) is a significant clinical problem characterized by refractory and severe hypoxemia secondary to elevated pulmonary vascular resistance resulting in right-to-left extrapulmonary shunting of deoxygenated blood. PPHN is associated with diverse cardiopulmonary disorders and a high early mortality rate for infants with severe PPHN. Surviving infants with PPHN have an increased risk of long-term morbidities. PPHN physiology can be categorized by (1) maladaptation: pulmonary vessels have normal structure and number but have abnormal vasoreactivity; (2) excessive muscularization: increased smooth muscle cell thickness and increased distal extension of muscle to vessels that are usually not muscularized; and (3) underdevelopment: lung hypoplasia associated with decreased pulmonary artery number. Treatment involves adequate lung recruitment, optimization of cardiac output and left ventricular function, and pulmonary vasodilators such as inhaled nitric oxide. Infants who fail to respond to conventional therapy should be evaluated for lethal lung disorders including alveolar-capillary dysplasia, T-box transcription factor 4 gene, thyroid transcription factor-1, ATP-binding cassette A3 gene, and surfactant protein diseases.

Nitric oxide and the brain. Part 2: Effects following neonatal brain injury-friend or foe?

Nitric oxide (NO) has critical roles in a wide variety of key biologic functions and has intricate transport mechanisms for delivery to key distal tissues under normal conditions. However, NO also plays important roles during disease processes, such as hypoxia-ischemia, asphyxia, neuro-inflammation, and retinopathy of prematurity. The effects of exogenous NO on the developing neonatal brain remain controversial. Inhaled NO (iNO) can be neuroprotective or toxic depending on a variety of factors, including cellular redox state, underlying disease processes, duration of treatment, and dose. This review identifies key gaps in knowledge that should prompt further investigation into the possible role of iNO as a therapeutic agent after injury to the brain. IMPACT: NO is a key signal mediator in the neonatal brain with neuroprotective and neurotoxic properties. iNO, a commonly used medication, has significant effects on the neonatal brain. Dosing, duration, and timing of administration of iNO can affect the developing brain. This review article summarizes the roles of NO in association with various disease processes that impact neonates, such as brain hypoxia-ischemia, asphyxia, retinopathy of prematurity, and neuroinflammation. The impact of this review is that it clearly describes gaps in knowledge, and makes the case for further, targeted studies in each of the identified areas.

Early assessment of lung aeration using an ultrasound score as a biomarker of developing bronchopulmonary dysplasia: a prospective observational study

The objective of this study was to assess the predictive value of a lung ultrasound (LUS) score in the development of moderate-severe bronchopulmonary dysplasia (sBPD). This was a prospective  observational diagnostic accuracy study in a third-level neonatal intensive care unit. Preterm infants with a gestational age below 32 weeks were included. A LUS score (range 0-24 points) was calculated by assessing aeration semiquantitatively (0-3 points) in eight lung zones on the 7th day of life (DOL) and repeated on the 28th DOL. ROC curves and logistic regression were used for analysis. Forty-two preterm infants were included. The LUS on the 7th DOL had an area under the receiver operating characteristic curve (AUROC) of 0.94 (95% CI: 0.87-1) for the prediction of sBPD (optimal cutoff of ≥8 points: sensitivity 93%, specificity 91%). The LUS score was independently associated with sBPD [OR 2.1 (95% CI: 1.1-3.9), p = 0.022, for each additional point in the score]. Conclusions: Lung aeration as assessed by LUS on the 7th DOL may predict the development of sBPD.

A quality improvement project improving the value of iNO utilization in preterm and term infants

OBJECTIVE

Inhaled NO (iNO) is used in the NICU for management of hypoxemic respiratory failure. The cost of iNO is significant and does not consistently improve outcomes in infants <34 weeks.

PROJECT DESIGN

Our team used The Model for Improvement to design a quality improvement project to utilize iNO for appropriate indications, ensure response to therapy and initiate timely weaning. The project was carried out at a Level IV NICU and successful interventions spread to a smaller Level III NICU.

RESULTS

This project demonstrated significant improvement in all measures; total iNO hours per month, average iNO hours per patient, and the percentage of prolonged iNO courses. With an estimated cost of $115/h, the cost per patient for iNO use declined by half from $21,620 to $10,580.

CONCLUSIONS

Our team improved the value of iNO utilization at our institution and spread successful interventions to another NICU in our network.

The future of Cochrane Neonatal

Cochrane Neonatal was first established in 1993, as one of the original review groups of the Cochrane Collaboration. In fact, the origins of Cochrane Neonatal precede the establishment of the collaboration. In the 1980's, the National Perinatal Epidemiology Unit at Oxford, led by Dr. Iain Chalmers, established the "Oxford Database of Perinatal Trials" (ODPT), a register of virtually all randomized controlled trials in perinatal medicine to provide a resource for reviews of the safety and efficacy of interventions used in perinatal care and to foster cooperative and coordinated research efforts in the perinatal field [1]. An effort that was clearly ahead of its time, ODPT comprised four main elements: a register of published reports of trials; a register of unpublished trials; a register of ongoing and planned trials; and data derived from pooled overviews (meta-analyses) of trials. This core effort grew into the creation of the seminal books, "Effective Care in Pregnancy and Childbirth" as well as "Effective Care of the Newborn Infant" [2,3]. As these efforts in perinatal medicine grew, Iain Chalmers thought well beyond perinatal medicine into the creation of a worldwide collaboration that became Cochrane [4]. The mission of the Cochrane Collaboration is to promote evidence-informed health decision-making by producing high-quality, relevant, accessible systematic reviews and other synthesized research evidence (www.cochrane.org). Cochrane Neonatal has continued to be one of the most productive review groups, publishing between 25 tpo to 40 new or updated systematic reviews each year. The impact factor has been steadily increasing over four years and now rivals most of the elite journals in pediatric medicine. Cochrane Neonatal has been a worldwide effort. Currently, there are 404 reviews involving 1206 authors from 52 countries. What has Cochrane done for babies? Reviews from Cochrane Neonatal have informed guidelines and recommendations worldwide. From January 2018 through June 2020, 77 international guidelines cited 221 Cochrane Neonatal reviews. These recommendations have included recommendations of the use of postnatal steroids, inhaled nitric oxide, feeding guidelines for preterm infants and other core aspects of neonatal practice. In addition, Cochrane Reviews has been the impetus for important research, including the large-scale trial of prophylactic indomethacin therapy, a variety of trials of postnatal steroids, trials of emollient ointment and probiotic trials [6]. While justifiably proud of these accomplishments, one needs to examine the future contribution of Cochrane Neonatal to the neonatal community. The future of Cochrane Neonatal is inexorably linked to the future of neonatal research. Obviously, there is no synthesis of trials data if, as a community, we fail to provide the core substrate for that research. As we look at the current trials' environment, fewer randomized controlled trial related to neonates are being published in recent years. A simple search of PubMed, limiting the search to "neonates" and "randomized controlled trials" shows that in the year 2000, 321 randomized controlled trials were published. These peaked five years ago, in 2015, with close to 900 trials being published. However, in 2018, only 791 studies are identified. Does this decrease represent a meaningful change in the neonatal research environment? Quite possibly. There are shifting missions of clinical neonatology at academic medical institutions, at least in the United States, with a focus on business aspects as well as other important competing clinical activities. Quality improvement has taken over as one of the major activities at both private and academic neonatal practices. Clearly, this is a needed improvement. All units at levels need to be dedicated to improving the outcomes of the sick and fragile population we care for. However, this need not be at the expense of formal clinical trials. It is understandable that this approach would be taken. Newer interventions frequently relate to complex systems of care and not the simple single interventions. Even trials that might traditionally have been done as randomized controlled trials, such as the introduction of a new mode of ventilation, are in reality complex challenges to the ability of institutions to create systems to adapt to these new technologies. Cost of doing trials has always been a barrier. The challenging regulatory and ethical environment contributes to these problems as well [7]. Despite these barriers, how does the research agenda of the neonatal community move forward in the 21st Century? We need to reassess how we create and disseminate our research findings. Innovative trial designs will allow us to address complex issues that we may not have tackled with conventional trials. Adaptive designs may allow us to look at potentially life-saving therapies in a way that feel more efficient and more ethical [8]. Clarifying issues such as the use of inhaled nitric oxide in preterm infants would be greatly served if we even knew whether or not there are hypoxemic preterm infant who would benefit from this therapy [9]. Current trials do not suggest so, yet current practice tells us that a significant number of these babies will receive inhaled nitric oxide [10-13]. Adaptive design, such as those done with trials of extracorporeal membrane oxygenation (ECMO), would allow us to quickly assess whether, in fact, these therapies are life-saving and allow us to consider whether or not further trials are needed [14,15]. Our understanding that many interventions involve entire systems approaches does not relegate us only to doing quality improvement work. Cluster designs may allow us to test more complex interventions that have usually been under the purview of quality improvement [16-18]. Cluster trials are well suited for such investigations and can be done with the least interruption to ongoing care. Ultimately, quality improvement is the application of the best evidence available (evidence-based medicine is "what to do" and evidence-based practice is "how to do"). [19,20]. Nascent efforts, such as the statement on "embedding necessary research into culture and health" (the ENRICH statement) call for the conduct of large, efficient pragmatic trials to evaluate neonatal outcomes, as in part called for in the ALPHA Collaboration [21,22]. This statement envisions an international system to identify important research questions by consulting regularly with all stakeholders, including patients, public health professionals, researchers, providers, policy makers, regulators, funders of industry. The ENRICH statement envisions a pathway to enable individuals, educational institutions, hospitals and health-care facilities to confirm their status as research-friendly by integrating an understanding of trials, other research and critical thinking and to teaching learning and culture, as well as an engagement with funders, professional organizations and regulatory bodies and other stake holders to raise awareness of the value of efficient international research to reduce barriers to large international pragmatic trials and other collaborative studies. In the future, if trials are to be done on this scale or trials are prospectively designed to be analyzed together, core outcome measures must be identified and standardized. That clinical trials supply estimates of outcomes that are relevant to patients and their families is critical. In addition, current neonatal research evaluates many different outcomes using multiple measures. A given measure can have multiple widely used definitions. Bronchopulmonary dysplasia (or chronic lung disease just to add to the confusion) quickly comes to mind [23,24]. The use of multiple definitions when attempting to measure the same outcome prevents synthesis of trial results and meta-analysis and hinders efforts to refine our estimates of effects. Towards that end, Webbe and colleagues have set out to develop a core outcome set for neonatal research [25]. Key stakeholders in the neonatal community reviewed multiple outcomes reported in neonatal trials and qualitative studies. Based on consensus, key outcome measures were identified, including survival, sepsis, necrotizing enterocolitis, brain injury on imaging, retinopathy or prematurity, gross motor ability, general cognitive ability, quality of life, adverse events, visual impairment or blindness, hearing impairment or deafness, chronic lung disease/bronchopulmonary dysplasia. Trials registration has to be a continued focus of the neonatal community. Trials registration allows for systematic reviewers to understand whether or not reporting bias has occurred [26]. It also allows for transparent incorporation of these core outcome measures. Ultimately, trials registration should include public reporting of all of these core outcomes and, in the future, access to data on an individual level such that more sophisticated individual patient data meta-analysis could occur. Lastly, there is no reason to see clinical trials and quality improvement as separate or exclusive activities. In fact, in the first NICQ Collaborative, conducted by Vermont Oxford Network, participation in a trial of postnatal steroids was considered part of the quality improvement best practices as opposed to simply choosing an as-of-yet unproven approach to use of this potent drug [27]. What role will Cochrane Neonatal play as we move forward in the 21st Century? As the neonatal community moves forward with its' research agenda, Cochrane Neonatal must not only follow but also lead with innovative approaches to synthesizing research findings. Cochrane Neonatal must continue to work closely with guideline developers. The relationship between systematic review production and guideline development is clearly outlined in reports from the Institute of Medicine [28,29]. Both are essential to guideline development; the systematic review group culling the evidence for the benefits and harms of a given intervention and the guideline group addressing the contextual issues of cost, feasibility, implementation and the values and preferences of individuals and societies. Most national and international guidelines groups now routinely use systematic reviews as the evidence basis for their guidelines and recommendations. Examples of the partnership between Cochrane Neonatal and international guideline development can be seen in our support of the World Health Organization (WHO) guidelines on the use of vitamin A or the soon to be published recommendations from the International Liaison Committee on Resuscitation (ILCOR) on cord management in preterm and term infants [30]. In the future, we need to collaborate early in the guideline development process so that the reviews are fit for purpose and meet the needs of the guideline developers and the end users. Towards this end, all Cochrane Neonatal reviews now contain GRADE assessments of the key clinical findings reported in the systematic review [31]. Addition of these assessments addresses the critical issue of our confidence in the findings. We are most confident in evidence provided by randomized controlled trials but this assessment can be can be downgraded if the studies that reported on the outcome in question had a high risk of bias, indirectness, inconsistency of results, or imprecision, or where there is evidence of reporting bias. Information provided by GRADE assessments is seen as critical in the process of moving from the evidence to formal recommendations [32]. We need to explore complex reviews, such as network (NMA) or multiple treatment comparison (MCT) meta-analyses, to address issues not formally addressed in clinical trials [33]. In conditions where there are multiple effective interventions, it is rare for all possible interventions to have been tested against each other [34]. A solution could be provided by network meta-analysis, which allows for comparing all treatments with each other, even if randomized controlled trials are not available for some treatment comparisons [34]. Network meta-analysis uses both direct (head-to-head) randomized clinical trial (RCT) evidence as well as indirect evidence from RCTs to compare the relative effectiveness of all included interventions [35]. However, Mills and colleagues note that the methodological quality of MTCs may be difficult for clinicians to interpret because the number of interventions evaluated may be large and the methodological approaches may be complex [35]. Cochrane Neonatal must take a role in both the creation of such analyses and the education of the neonatal community regarding the pitfalls of such an approach. The availability of individual patient data will make more sophisticated analyses more available to the community. Although the current crop of individual patient data meta-analyses (including the reviews of elective high frequency ventilation, inhaled nitric oxide and oxygen targets) have not differed substantially from the findings of the trials level reviews (suggesting that, in fact, sick neonates are more alike that unalike), there still will be a large role for individual patient data meta-analysis, at least to end the unfound conclusions that these therapies are effective in various subgroups (be it issues of sex, disease severity, or clinical setting) [36-39]. Future trials should take a lesson from the NeOProM Collaborative [37,39]. Given the difficulty in generating significant sample size and creating funding in any single environment, trials with similar protocols should be conducted in a variety of healthcare settings with an eye towards both study level and individual patient level meta-analysis at the conclusion of those trials, allowing for broader contribution to the trials data, more rapid accrual of sample size, and more precise results. We need to educate the neonatal community regarding the use and abuse of diagnostic tests. Diagnostic tests are a critical component of healthcare but also contribute greatly to the cost of medical care worldwide. These costs include the cost of the tests themselves and the costs of misdiagnosis and treatment of individuals who will not benefit from those treatments. Clinicians may have a limited understanding of diagnostic test accuracy, the ability of a diagnostic test to distinguish between patients with and without the disease or target condition [41,42]. Efforts such as Choosing Wisely have tried to identify these deficiencies [40]. As Cochrane has increased the general literacy of both the medical and general population regarding the interpretation of the results of interventions on various diseases, so should Cochrane move forward and improve the understanding of diagnostic testing. We need to become more efficient at creating and maintaining our reviews. The time spent to produce systematic reviews is far too great. In average, it takes between 2½ to 6½ years to produce a systematic review, requiring intense time input for highly trained and expensive experts. Innovations in the ways in which we produce systematic reviews can make the review process more efficient by outsourcing some of the tasks or crowdsourcing to machine learning. We need to let the crowd and machine learning innovations help us sort the massive amounts of information needed to conduct systematic reviews. It can also allow for "live" updating of critical reviews where the research landscape is quickly changing [43]. Lastly, Cochrane Neonatal must focus more on users of the reviews and not necessarily authors of the reviews. Current Cochrane programming speaks of Cochrane training with an eye towards developing the skills of individuals who will conduct systematic reviews. While this is clearly needed and laudable, the fact of the matter is that most of the community will be "users" of the reviews. Individuals who need to understand how to use and interpret the findings of systematic reviews. These review users include clinicians, guideline developers, policy makers and families. Incorporation of GRADE guidelines has been a huge step in adding transparency to the level of uncertainty we have in our findings. From a family's perspective, we need to overcome the environment of mistrust or misunderstanding of scientific evidence and how we convey what we know, and our uncertainty about what we know, to parents and families.

The immediate efficacy of inhaled nitric oxide treatment in preterm infants with acute respiratory failure during neonatal transport

AIM

The aim of our review was to describe the clinical response to inhaled nitric oxide (iNO) in a series of preterm babies in respiratory failure during uplift transfers to a neonatal intensive care unit.

METHODS

We performed a retrospective review of critical newborns with gestational age <34⁺⁰  weeks transferred from January 2013 to December 2018. Data were extracted from our Clinical Information System for transport. The primary measure of this review was to assess whether a significant improvement in the oxygenation saturation index (OSI) occurred following the use of iNO.

RESULTS

Thirty preterm babies <34⁺⁰  weeks were included in our review. OSI, as a measure of oxygenation, did not statistically improve as an immediate response to iNO from referral to receiving hospital (17.1 vs 16.4; P = .7). We found that pH (7.15 vs 7.29; P = .004) and pCO2 (8.1 vs 6.3; P = .05) significantly improved probably based on ventilation management.

CONCLUSION

Following the recommendations of the American Academy of Paediatrics and other organizations, iNO should not routinely be used during the neonatal transfer of preterm babies <34⁺⁰ in respiratory failure. We need to conduct further studies to establish which selected preterm patients would benefit from being treated with iNO.

Impact of inhaled nitric oxide stewardship programme in a neonatal intensive care unit

AIM

Inhaled nitric oxide (iNO) is the most common, although expensive, therapy for persistent pulmonary hypertension of the newborn and hypoxaemic respiratory failure. With significant variation in iNO delivery practices amongst clinicians, this study aimed to assess the effectiveness of a stewardship programme in increasing clinician compliance with revised, standardised protocols and to measure the impact of compliance on iNO therapy use.

METHODS

Initiation and weaning protocols for iNO were introduced to the neonatal intensive care unit at The Centenary Hospital on 01 March 2016. A 2-year stewardship programme was utilised to assess protocol compliance and the resulting iNO usage impacts were measured. A combined retrospective and prospective study from 1 March 2014 to 28 February 2018 was conducted to compare the patterns of iNO utilisation between the pre- and post-stewardship cohorts.

RESULTS

The pre-stewardship cohort incorporated 18 neonates, receiving 19 iNO treatment episodes, and 18 neonates, receiving 21 iNO treatment episodes, in the post-stewardship cohort. No significant difference in patient demographics was determined. Compliance with the protocols improved from 61% in year 1 to 88% in year 2 of the stewardship programme. Significant reductions were observed in median total hours of iNO therapy per patient (P = 0.0014) and in median time from therapy initiation to initial wean (P < 0.0001). The cost of iNO therapy reduced 52% during the stewardship programme with no increase in adverse patient outcomes.

CONCLUSION

An iNO stewardship programme could be safely implemented in any NICU leading to increased protocol compliance with a beneficial reduction in iNO usage and cost.

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.

Bronchopulmonary dysplasia

In the absence of effective interventions to prevent preterm births, improved survival of infants who are born at the biological limits of viability has relied on advances in perinatal care over the past 50 years. Except for extremely preterm infants with suboptimal perinatal care or major antenatal events that cause severe respiratory failure at birth, most extremely preterm infants now survive, but they often develop chronic lung dysfunction termed bronchopulmonary dysplasia (BPD; also known as chronic lung disease). Despite major efforts to minimize injurious but often life-saving postnatal interventions (such as oxygen, mechanical ventilation and corticosteroids), BPD remains the most frequent complication of extreme preterm birth. BPD is now recognized as the result of an aberrant reparative response to both antenatal injury and repetitive postnatal injury to the developing lungs. Consequently, lung development is markedly impaired, which leads to persistent airway and pulmonary vascular disease that can affect adult lung function. Greater insights into the pathobiology of BPD will provide a better understanding of disease mechanisms and lung repair and regeneration, which will enable the discovery of novel therapeutic targets. In parallel, clinical and translational studies that improve the classification of disease phenotypes and enable early identification of at-risk preterm infants should improve trial design and individualized care to enhance outcomes in preterm infants.

Oxygen radical disease in the newborn, revisited: Oxidative stress and disease in the newborn period

Thirty years ago, there was an emerging appreciation for the significance of oxidative stress in newborn disease. This prompted a renewed interest in the impact of oxygen therapy for the newborn in the delivery room and beyond, especially in premature infants. Today, the complexity of oxidative stress both in normal regulation and pathology is better understood, especially as it relates to neonatal mitochondrial oxidative stress responses to hyperoxia. Mitochondria are recipients of oxidative damage and have a propensity for oxidative self-injury that has been implicated in the pathogenesis of neonatal lung diseases. Similarly, both intrauterine growth restriction (IUGR) and macrosomia are associated with mitochondrial dysfunction and oxidative stress. Additionally, reoxygenation with 100% O₂ in a hypoxic-ischemic newborn lamb model increased the production of pro-inflammatory cytokines in the brain. Moreover, the interplay between inflammation and oxidative stress in the newborn is better understood because of animal studies. Transcriptomic analyses have found a number of genes to be differentially expressed in murine models of bronchopulmonary dysplasia (BPD). Epigenetic changes have also been detected both in animal models of BPD and premature infants exposed to oxygen. Antioxidant therapy to prevent newborn disease has not been very successful; however, new therapeutic principles, like melatonin, are under investigation.

The Off-Label Use of Inhaled Nitric Oxide as a Rescue Therapy in Neonates with Refractory Hypoxemic Respiratory Failure: Therapeutic Response and Risk Factors for Mortality

OBJECTIVES

The indication of inhaled nitric oxide (iNO) used in preterm infants has not been well defined. Neonates with refractory hypoxemia may benefit from the pulmonary vasodilatory effects of iNO. The aim of this study was to investigate the off-label use of iNO as a rescue therapy.

METHODS

Between January 2010 and December 2017, all neonates who received iNO as a rescue therapy from a tertiary-level medical center were enrolled, and those who were not diagnosed with persistent pulmonary hypertension of newborn (PPHN) were defined as having received off-label use of iNO. The controls were 636 neonates with severe respiratory failure requiring high-frequency oscillatory ventilation but no iNO.

RESULTS

A total of 206 neonates who received iNO as a rescue therapy were identified, and 84 (40.8%) had off-label use. The median (interquartile) gestational age was 30.5 (26.3-37.0) weeks. Neonates receiving iNO had significantly more severe respiratory failure and a higher oxygenation index than the controls (p < 0.001). Respiratory distress syndrome and secondary pulmonary hypertension after severe bronchopulmonary dysplasia (BPD) were the most common causes of the off-label iNO prescription. Of the 84 neonates with off-label use of iNO, 53 (63.1%) had initial improvement in oxygenation, but 44 (52.4%) eventually died. The overall mortality rate was 41.7% (86/206). After multivariate logistic regression, extremely preterm (odds ratio [OR] 5.51; p < 0.001), presence of pulmonary hemorrhage (OR 2.51; p = 0.036) and severe hypotension (OR 2.78; p = 0.008) were the independent risk factors for final mortality.

CONCLUSIONS

iNO is applicable to be an off-label rescue therapy for premature neonates with refractory hypoxemia due to severe pulmonary hypertension and bronchopulmonary dysplasia.

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.

Respiratory severity score as a predictive factor for severe bronchopulmonary dysplasia or death in extremely preterm infants

Background

Despite significant advances in neonatology, bronchopulmonary dysplasia (BPD) remains the most common cause of serious morbidity and mortality in premature infants. The aim of the present study was to determine associations between the respiratory severity score (RSS) with death or BPD in premature infants.

Methods

This was a retrospective study conducted between January 2010 and December 2014. We enrolled preterm infants with a gestational age of less than 28 weeks who were supported by mechanical ventilation for more than a week during the first 4 weeks of life. We collected the RSS scores on day of life 2, 7, 14, 21 and 28. The correlations between postnatal RSSs and death or severe BPD were analyzed using multivariate logistic regression.

Results

Of the 138 eligible infants, 66 infants (47.8%) either died or developed severe BPD. The RSS cut-off values for predicting severe BPD or death were 3.0 for postnatal day (PND) 14 with an odds ratio (OR) of 11.265 (p = 0.0006, 95% confidence interval (CI), 2.842 to 44.646), 3.6 for PND 21 with an OR of 15.162 (p = 0.0003, 95% CI, 3.467 to 66.316), and 3.24 for PND 28 with an OR of 10.713 (p = 0.0005, 95% CI, 2.825 to 40.630).

Conclusion

Strong correlations were observed between the RSSs on PND 14, 21, and 28 and death or subsequent severe BPD. The RSS could provide a simple estimate of severe BPD or death., Further research with a larger study population is necessary to validate the usefulness of the RSS for predicting severe BPD or death.

Electronic supplementary material

The online version of this article (10.1186/s12887-019-1492-9) contains supplementary material, which is available to authorized users.

Prevention of Bronchopulmonary Dysplasia: A Summary of Evidence-Based Strategies

Bronchopulmonary dysplasia (BPD) is the most common chronic complication associated with extremely preterm birth. Although BPD is now an uncommon condition in infants born with birthweights higher than 1,500 g, among infants born at or near the current limits of viability, BPD rates have not improved over the past 2 to 3 decades and may be increasing. No single therapeutic intervention is effective at preventing BPD. As such, clinicians must use multiple evidence-based strategies to help reduce BPD rates. This review examines current evidence-based approaches to BPD prevention, primarily focusing on data obtained from randomized controlled trials.

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.

Outcomes of early inhaled nitric oxide use in premature African American neonates

OBJECTIVE

Meta-analysis of individual-patient clinical trial data suggests that inhaled nitric oxide (iNO) improves respiratory outcomes in premature African American neonates. We hypothesized that early iNO therapy would be associated with lower mortality and less chronic lung disease (CLD) in extremely premature African American neonates.

STUDY DESIGN

We conducted a retrospective cohort study of propensity score- and race-matched neonates 22-29 weeks gestation who were mechanically ventilated for treatment of respiratory distress and associated pulmonary hypertension (RDS + PPHN). We evaluated the association of iNO within 7 days of life with in-hospital mortality and CLD, using Cox proportional hazards regression and logistic regression, respectively.

RESULT

Among 178 matched pairs of African American patients, iNO was not associated with lower mortality (HR = 0.94, 95% CI 0.69-1.30) or less CLD (OR = 0.94, 95% CI 0.47-1.87).

CONCLUSIONS

Early, off-label iNO use is not associated with improved outcomes in premature African American neonates with RDS + PPHN.

The efficacy of inhaled nitric oxide treatment in premature infants with acute pulmonary hypertension

BACKGROUND

Although inhaled nitric oxide (iNO) therapy in term infants with pulmonary hypertension (PHT) has demonstrated definite benefit, the use of iNO in preterm infants remains inconclusive.

AIMS

To evaluate the impact of iNO treatment in premature infants with acute PHT.

STUDY DESIGN

Retrospective cohort.

SUBJECTS

Infants < 34 weeks' gestational age, admitted during 2010-2016 to two neonatal units, having treated with iNO for confirmed PHT. A positive response was defined by FiO₂ reduction ≥20% within 3-h post iNO initiation. Early PHT was defined when developed within the first 72 h of age.

OUTCOME MEASURES

The primary outcome was the evaluation of the acute response to iNO administration. Secondary outcomes included the comparison of neonatal characteristics and outcomes between positive and negative responders, and early or late PHT infants.

RESULTS

Of the 55 infants of our cohort, 39 (71%) had a positive response to iNO administration. No differences noted regarding bronchopulmonary dysplasia, intraventricular haemorrhage or other morbidities; however, positive responders had significantly higher survival rate in overall (77 vs 21%, p = 0.001) and within early PHT subgroup (74 vs 33%, p = 0.044). Regression analysis revealed that oligohydramnios (OR 2.834, 95%CI 1.652-6.070) and early PHT (OR 1.953, 95%CI 1.377-2.930) were significantly related with a positive response.

CONCLUSIONS

Preterm infants with confirmed acute PHT respond in significant proportion to the iNO administration, especially in the background of oligohydramnios or the development of early PHT.

Treatment with nitric oxide in the neonatal intensive care unit is associated with increased risk of childhood cancer

AIM

This study aimed to determine whether neonatal intensive care therapies increase the risk of carcinogenesis in childhood.

METHODS

This study used population-based data on 1 072 957 infants born in New South Wales, Australia, between 2000 and 2011 and multivariate logistic regression to examine any associations between therapies used in the neonatal intensive care unit and diagnoses of cancer until mid 2012.

RESULTS

A total of 1126 of 1 072 957 (0.1%) children were diagnosed with cancer. Cancer risk was significantly increased by preterm birth (gestation <37 weeks; adjusted odds ratio (aOR) 1.3 (95% confidence interval: 1.0-1.6), birth weight ≥4 kg (aOR 1.4, 1.2-1.6) and caesarean delivery (aOR 1.2, 1.1-1.4). Extremely preterm (<28 weeks of gestation) infants were more likely to develop hepatic tumours (aOR 12.7, 3.3-48.3) than term infants. The only therapy used in the neonatal intensive care that was independently associated with an increased risk of cancer was nitric oxide (aOR 8.6, 4.3-17.4). Eight of the 790 (1%) infants treated with nitric oxide developed cancer (gestation range 30-41 weeks, age of cancer diagnosis: four months-five years).

CONCLUSION

Treatment with nitric oxide was associated with a higher risk of childhood cancer. These findings require further research.

Umbilical cord blood metabolomics reveal distinct signatures of dyslipidemia prior to bronchopulmonary dysplasia and pulmonary hypertension

Pulmonary hypertension (PH) is a common consequence of bronchopulmonary dysplasia (BPD) and remains a primary contributor to increased morbidity and mortality among preterm infants. Unfortunately, at the present time, there are no reliable early predictive markers for BPD-associated PH. Considering its health consequences, understanding in utero perturbations that lead to the development of BPD and BPD-associated PH and identifying early predictive markers is of utmost importance. As part of the discovery phase, we applied a multiplatform metabolomics approach consisting of untargeted and targeted methodologies to screen for metabolic perturbations in umbilical cord blood (UCB) plasma from preterm infants that did ( n = 21; cases) or did not ( n = 21; controls) develop subsequent PH. A total of 1,656 features were detected, of which 407 were annotated by metabolite structures. PH-associated metabolic perturbations were characterized by reductions in major choline-containing phospholipids, such as phosphatidylcholines and sphingomyelins, indicating altered lipid metabolism. The reduction in UCB abundances of major choline-containing phospholipids was confirmed in an independent validation cohort consisting of UCB plasmas from 10 cases and 10 controls matched for gestational age and BPD status. Subanalyses in the discovery cohort indicated that elevations in the oxylipins PGE1, PGE2, PGF2a, 9- and 13-HOTE, 9- and 13-HODE, and 9- and 13-KODE were positively associated with BPD presence and severity. This expansive evaluation of cord blood plasma identifies compounds reflecting dyslipidemia and suggests altered metabolite provision associated with metabolic immaturity that differentiate subjects, both by BPD severity and PH development.

Changes in the nitric oxide pathway of the pulmonary vasculature after exposure to hypoxia in swine model of neonatal pulmonary vascular disease

Neonatal pulmonary vascular disease (PVD) is increasingly recognized as a disease that complicates the cardiopulmonary adaptations after birth and predisposes to long-term cardiopulmonary disease. There is growing evidence that PVD is associated with disruptions in the nitric oxide (NO)-cGMP-phosphodiesterase 5 (PDE5) pathway. Examination of the functionality of different parts of this pathway is required for better understanding of the pathogenesis of neonatal PVD. For this purpose, the role of the NO-cGMP-PDE5 pathway in regulation of pulmonary vascular function was investigated in vivo, both at rest and during exercise, and in isolated pulmonary small arteries in vitro, in a neonatal swine model with hypoxia-induced PVD. Endothelium-dependent vasodilatation was impaired in piglets with hypoxia-induced PVD both in vivo at rest and in vitro. Moreover, the responsiveness to the NO-donor SNP was reduced in hypoxia-exposed piglets in vivo, while the relaxation to SNP and 8-bromo-cyclicGMP in vitro were unaltered. Finally, PDE5 inhibition-induced pulmonary vasodilatation was impaired in hypoxia-exposed piglets both in vitro and in vivo at rest. During exercise, however, the pulmonary vasodilator effect of PDE5 inhibition was significantly larger in hypoxia-exposed as compared to normoxia-exposed piglets. In conclusion, the impaired endothelium-dependent vasodilatation in piglets with hypoxia-induced PVD was accompanied by reduced responsiveness to NO, potentially caused by altered sensitivity and/or activity of soluble guanylyl cyclase (sGC), resulting in an impaired cGMP production. Our findings in a newborn animal model for neonatal PVD suggests that sGC stimulators/activators may be a novel treatment strategy to alleviate neonatal PVD.

Ancestry and genetic associations with bronchopulmonary dysplasia in preterm infants

Bronchopulmonary dysplasia in premature infants is a common and often severe lung disease with long-term sequelae. A genetic component is suspected but not fully defined. We performed an ancestry and genome-wide association study to identify variants, genes, and pathways associated with survival without bronchopulmonary dysplasia in 387 high-risk infants treated with inhaled nitric oxide in the Trial of Late Surfactant study. Global African genetic ancestry was associated with increased survival without bronchopulmonary dysplasia among infants of maternal self-reported Hispanic white race/ethnicity [odds ratio (OR) = 4.5, P = 0.01]. Admixture mapping found suggestive outcome associations with local African ancestry at chromosome bands 18q21 and 10q22 among infants of maternal self-reported African-American race/ethnicity. For all infants, the top individual variant identified was within the intron of NBL1, which is expressed in midtrimester lung and is an antagonist of bone morphogenetic proteins ( rs372271081 , OR = 0.17, P = 7.4 × 10^-7). The protective allele of this variant was significantly associated with lower nitric oxide metabolites in the urine of non-Hispanic white infants ( P = 0.006), supporting a role in the racial differential response to nitric oxide. Interrogating genes upregulated in bronchopulmonary dysplasia lungs indicated association with variants in CCL18, a cytokine associated with fibrosis and interstitial lung disease, and pathway analyses implicated variation in genes involved in immune/inflammatory processes in response to infection and mechanical ventilation. Our results suggest that genetic variation related to lung development, drug metabolism, and immune response contribute to individual and racial/ethnic differences in respiratory outcomes following inhaled nitric oxide treatment of high-risk premature infants.

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

IMPORTANCE

Pulmonary hypoplasia affects a very small percentage of preterm neonates, but its presence is associated with high rates of mortality.

OBJECTIVE

To determine whether treatment with inhaled nitric oxide during the first week of life was associated with improved in-hospital survival in a cohort of extremely preterm neonates with pulmonary hypoplasia.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study used data from the Pediatrix Medical Group's Clinical Data Warehouse, a data set containing information from more than 350 neonatal intensive care units in 35 US states and Puerto Rico. Since inhaled nitric oxide was not randomly prescribed, we used 1-to-1 propensity score matching to reduce the imbalance of measured covariates between the 2 treatment groups. The initial, unmatched cohort included singleton neonates who were born between 22 and 29 weeks' gestation, had a birth weight of 400 g or more, were diagnosed with pulmonary hypoplasia as a cause of their respiratory distress, remained free of major anomalies, and were discharged between January 1, 2000, and December 31, 2014. We defined exposure as the initiation of inhaled nitric oxide on day t in days 0 to 7 of the life of a neonate. Each exposed neonate was matched 1-to-1 to a neonate who had not initiated inhaled nitric oxide on a given day.

MAIN OUTCOMES AND MEASURES

The primary outcome was mortality defined as death prior to transfer or discharge home. Secondary outcomes were any-stage necrotizing enterocolitis, retinopathy of prematurity requiring treatment, chronic lung disease, and periventricular leukomalacia.

RESULTS

Among 92 635 neonates in our study sample, we identified 767 (0.8%) with pulmonary hypoplasia who met all study inclusion criteria, of whom 185 (0.2%) were exposed to inhaled nitric oxide. Among 151 matched pairs of exposed and unexposed neonates, we did not identify a significant association between inhaled nitric oxide use and mortality (hazard ratio [HR], 0.79; 95% CI, 0.57-1.11). Subgroup analyses of neonates with and without persistent pulmonary hypertension (PPHN) likewise revealed no significant association between inhaled nitric oxide use and mortality (pulmonary hypoplasia with PPHN: HR, 0.67; 95% CI, 0.45-1.01; pulmonary hypoplasia without PPHN: HR, 1.11; 95% CI, 0.61-2.02), but these findings may have been influenced by ascertainment bias.

CONCLUSIONS AND RELEVANCE

Early treatment with inhaled nitric oxide is not associated with improved survival among extremely preterm neonates with pulmonary hypoplasia. Clinical trials are warranted to clarify the matter.

Inhaled Nitric Oxide in Extremely Premature Neonates With Respiratory Distress Syndrome

BACKGROUND

Inhaled nitric oxide (iNO) is increasingly prescribed to extremely premature neonates with respiratory distress syndrome (RDS). Most of this off-label use occurs during the first week of life. We studied this practice, hypothesizing that it would not be associated with improved survival.

METHODS

We queried the Pediatrix Medical Group Clinical Data Warehouse to identify all neonates born at 22 to 29 weeks' gestation from 2004 to 2014. In our study sample, we included singletons who required mechanical ventilation for treatment of RDS and excluded those with anomalies. The primary outcome was death before discharge. Through a sequential risk set approach, each patient who received iNO during the first 7 days of life ("case patient") was matched by using propensity scores to a patient who had not received iNO at a chronological age before the case patient's iNO initiation age (defined as the index age for the matched pair). The association between iNO status and in-hospital mortality was evaluated in a Cox proportional hazards regression model by using age as the time scale with patients entering the risk set at their respective index age.

RESULTS

Among 37 909 neonates in our study sample, we identified 993 (2.6%) who received iNO. The 2 matched cohorts each contained 971 patients. We did not observe a significant association between iNO exposure and mortality (hazard ratio, 1.08; 95% confidence interval, 0.94-1.25; P = .29).

CONCLUSIONS

Off-label prescription of iNO is not associated with reduced in-hospital mortality among extremely premature neonates with RDS.

Race Effects of Inhaled Nitric Oxide in Preterm Infants: An Individual Participant Data Meta-Analysis

OBJECTIVE

To assess whether inhaled nitric oxide (iNO) improves survival without bronchopulmonary dysplasia (BPD) for preterm African American infants.

STUDY DESIGN

An individual participant data meta-analysis was conducted, including 3 randomized, placebo-controlled trials that enrolled infants born at  <34 weeks of gestation receiving respiratory support, had at least 15% (or a minimum of 10 infants in each trial arm) of African American race, and used a starting iNO of >5  parts per million with the intention to treat for 7 days minimum. The primary outcome was a composite of death or BPD. Secondary outcomes included death before discharge, postnatal steroid use, gross pulmonary air leak, pulmonary hemorrhage, measures of respiratory support, and duration of hospital stay.

RESULTS

Compared with other races, African American infants had a significant reduction in the composite outcome of death or BPD with iNO treatment: 49% treated vs 63% controls (relative risk, 0.77; 95% CI, 0.65-0.91; P = .003; interaction P = .016). There were no differences between racial groups for death. There was also a significant difference between races (interaction P = .023) of iNO treatment for BPD in survivors, with the greatest effect in African American infants (P = .005). There was no difference between racial groups in the use of postnatal steroids, pulmonary air leak, pulmonary hemorrhage, or other measures of respiratory support.

CONCLUSION

iNO therapy should be considered for preterm African American infants at high risk for BPD. iNO to prevent BPD in African Americans may represent an example of a racially customized therapy for infants.

Nitric oxide inhalations in bronchiolitis: A pilot, randomized, double-blinded, controlled trial

AIM

The aims of this pilot study were to determine safety, tolerability (primary outcome) and efficacy (secondary outcome) of high-dose inhaled nitric oxide for the treatment of infants with moderately severe bronchiolitis.

METHODS

This was a pilot, double-blinded, randomized controlled study (phase IIa). Intermittent inhalations of nitric oxide 160 ppm for 30 min or oxygen/air (control) were given 5 times/day to hospitalized infants (2-11 months) with acute bronchiolitis. Oxygen saturation, methemoglobin, and nitric dioxide (NO₂ ) levels and vital signs were monitored.

RESULTS

Forty-three infants were enrolled. Baseline characteristics were comparable in both study groups. Mean clinical score, comprised of four components: respiratory rate, use of accessory muscles, wheezes and crackles, and % room-air oxygen saturation, was 7.86 (±1.1) and 8.09 (±1.2) in the NO and control groups, respectively, consistent with moderate severity. The overall frequency of adverse events was similar between the groups. Repeated nitric oxide inhalations did not result in increased inhaled NO₂ levels or cumulative effect on methemoglobin levels. Secondary outcomes of efficacy were measured by length of hospitalization (LOS) in hours: LOS did not differ between groups. However, in a post-hoc analysis of a subgroup of infants hospitalized for >24 h (n = 24), the median LOS was shorter in the nitric oxide (41.9 h) than in the control group (62.5 h) (P = 0.014).

CONCLUSION

Our study was unable to detect a difference in side effects using intermittent high-dose nitric-oxide inhalation or supportive treatment alone, in infants with moderate bronchiolitis. Preliminary efficacy outcomes are encouraging.

A Pathogenic Relationship of Bronchopulmonary Dysplasia and Retinopathy of Prematurity? A Review of Angiogenic Mediators in Both Diseases

Bronchopulmonary dysplasia (BPD) and retinopathy of prematurity (ROP) are common and significant morbidities of prematurely born infants. These diseases have in common altered and pathologic vascular formation in the face of incomplete organ development. Therefore, it is reasonable to question whether factors affecting angiogenesis could have a joint pathogenic role for both diseases. Inhibition or induced expression of a single angiogenic factor is unlikely to be 100% causative or protective of either of BPD or ROP. It is more likely that interactions of multiple factors leading to disordered angiogenesis are present, increasing the likelihood of common pathways in both diseases. This review explores this possibility by assessing the evidence showing involvement of specific angiogenic factors in the vascular development and maldevelopment in each disease. Theoretical interactions of specific factors mutually contributing to BPD and ROP are proposed and, where possible, a timeline of the proposed relationships between BPD and ROP is developed. It is hoped that future research will be inspired by the theories put forth in this review to enhance the understanding of the pathogenesis in both diseases.

Effect of Inhaled Nitric Oxide on Survival Without Bronchopulmonary Dysplasia in Preterm Infants: A Randomized Clinical Trial

IMPORTANCE

Bronchopulmonary dysplasia (BPD) occurs in approximately 40% of infants born at younger than 30 weeks' gestation and is associated with adverse pulmonary and neurodevelopmental outcomes.

OBJECTIVE

To test whether administration of inhaled nitric oxide to preterm infants requiring positive pressure respiratory support on postnatal days 5 to 14 improves the rate of survival without BPD.

DESIGN, SETTING, AND PARTICIPANTS

This intent-to-treat study was a randomized clinical trial performed at 33 US and Canadian neonatal intensive care units. Participants included 451 neonates younger than 30 weeks' gestation with birth weight less than 1250 g receiving mechanical ventilation or positive pressure respiratory support on postnatal days 5 to 14. Enrollment spanned from December 23, 2009, to April 23, 2012, and neurodevelopmental outcome studies were completed by April 4, 2014.

INTERVENTIONS

Placebo (nitrogen) or inhaled nitric oxide initiated at 20 ppm was decreased to 10 ppm between 72 and 96 hours after starting treatment and then to 5 ppm on day 10 or 11. Infants remained on the 5-ppm dose until completion of therapy (24 days).

MAIN OUTCOMES AND MEASURES

The primary outcome was the rate of survival without BPD at 36 weeks' postmenstrual age (PMA). Secondary outcomes included BPD severity, postnatal corticosteroid use, respiratory support, survival, and neurodevelopmental outcomes at 18 to 24 months' PMA.

RESULTS

In total, 222 infants (52.3% male [n = 116]) received placebo, and 229 infants (50.2% male [n = 115]) received inhaled nitric oxide. Their mean (SD) gestation was 25.6 (1.5) vs 25.6 (1.4) weeks, and their mean (SD) birth weight was 750 (164) vs 724 (160) g. Survival without BPD at 36 weeks' PMA was similar between the placebo and inhaled nitric oxide groups (31.5% [n = 70] vs 34.9% [n = 80]) (odds ratio, 1.17; 95% CI, 0.79-1.73). Rates for severe BPD (26.6% [55 of 207] vs 20.5% [43 of 210]) and postnatal corticosteroid use for BPD (41.0% [91 of 222] vs 41.5% [95 of 229]) and the mean (SD) days of positive pressure respiratory support (55 [40] vs 54 [42]), oxygen therapy (88 [41] vs 91 [59]), and hospitalization (105 [37] vs 108 [54]) were equivalent between the 2 groups. No differences in the incidence of common morbidities were observed. Respiratory outcomes on discharge to home, at 1 year, and at age 18 to 24 months' PMA and neurodevelopmental assessments at 18 to 24 months' PMA did not differ between groups.

CONCLUSIONS AND RELEVANCE

Inhaled nitric oxide, initiated at 20 ppm on postnatal days 5 to 14 to high-risk preterm infants and continued for 24 days, appears to be safe but did not improve survival without BPD at 36 weeks' PMA or respiratory and neurodevelopmental outcomes at 18 to 24 months' PMA.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00931632.

Nitric oxide for the treatment of preterm infants with severe RDS and pulmonary hypertension

BACKGROUND

Inhaled nitric oxide (iNO) cannot be recommended for the routine treatment of respiratory failure in premature neonates, but it has been suggested that the effectiveness of iNO therapy should be further studied in more select preterm infants, such as those with persistent pulmonary hypertension of the newborn (PPHN).

OBJECTIVE

To evaluate the frequency of PPHN in very preterm infants with severe respiratory distress syndrome (RDS), to assess the effectiveness of iNO in these patients, and to individuate possible predictive factors for the response to iNO in preterm infants with RDS.

STUDY DESIGN

We retrospectively studied infants <30 weeks of gestational age or birth weight <1250 g, who were affected by severe RDS and treated with iNO during the first week of life. Clinical characteristics of infants with or without echocardiographic diagnosis of PPHN were compared, as well as those of responder or no responder to iNO therapy. Effectiveness of iNO was evaluated by recording changes of MAP, FiO₂ , SpO₂ /FiO₂ ratio, and oxygenation index (OI) before, and 3 ± 1, 6 ± 1, 12 ± 3, 24 ± 6, 48 ± 6, and 72 ± 12 h after beginning therapy.

RESULTS

We studied 42 (4.6%) infants, of whom 28 (67%) had PPHN and 14 (33%) did not. iNO therapy was associated with improved oxygenation in both the groups but it was quicker in the PPHN than in the no PPHN group. Multivariate analysis showed that FiO₂ >0.65, diagnosis of PPHN, and birth weight >750 g independently predicts effectiveness of iNO in very preterm infants with RDS.

CONCLUSION

We found that PPHN is a frequent complication of severe RDS in very preterm infants and iNO therapy can improve their oxygenation earlier than in infants without PPHN. iNO therapy is not recommended for the routinely treatment of RDS in premature neonates but in cases of concurrent diagnosis of PPHN it should be considered carefully.

Short-term and long-term outcomes of preterm neonates with acute severe pulmonary hypertension following rescue treatment with inhaled nitric oxide

OBJECTIVE

To describe short-term and long-term outcomes of preterm neonates with severe acute pulmonary hypertension (aPHT) in relation to response to rescue inhaled nitric oxide (iNO) therapy.

DESIGN

Retrospective cohort studyover a 6 year period.

SETTING

Tertiary neonatal intensive care unit.

PATIENTS

89 neonates <35 weeks gestational age (GA) who received rescue iNO for aPHT, including 62 treated at ≤3 days of age (early aPHT).

INTERVENTIONS

iNO ≥ 1 hour.

MAIN OUTCOME MEASURES

Positive responders (reduction in fraction of inspired oxygen (FiO₂) ≥0.20 within 1 hour of iNO) were compared with non-responders. Primary outcome was survival without moderate-to-severe disability at 18 months of age.

RESULTS

Mean (SD) GA and birth weight was 27.7 (3.0) weeks and 1077 (473) gm, respectively. Median (IQR) pre-iNO FiO₂ was 1.0 (1.0, 1.0). Positive response rate to iNO was 46%. Responders showed improved survival without disability (51% vs 15%; p<0.01), lower mortality (34% vs 71%; p<0.01) and disability among survivors (17% vs 50%; p=0.06). Higher GA (adjusted OR: 1.44 (95% CI 1.10 to 1.89)), aPHT in context of preterm prolonged rupture of membranes (6.26 (95% CI 1.44 to 27.20)) and positive response to rescue iNO (5.81 (95% CI 1.29 to, 26.18)) were independently associated with the primary outcome. Compared with late cases (>3 days of age), early aPHT had a higher response rate to iNO (61% vs 11%; p<0.01) and lower mortality (43% vs 78%; p<0.01).

CONCLUSION

A positive response to rescue iNO in preterm infants with aPHT is associated with survival benefit, which is not offset by long-term disability.

The roles of drug therapy given via the endotracheal tube to neonates

Many drugs are given to intubated neonates by the inhalation route. The optimum aerosol delivery system, however, has not been identified and there are many challenges in delivering drugs effectively to the lower airways of intubated neonates. The effectiveness of surfactant in prematurely born infants and nitric oxide has been robustly investigated. Other drugs are being used on very limited evidence.

Early Use of Inhaled Nitric Oxide in Preterm Infants: Is there a Rationale for Selective Approach?

Background Inhaled nitric oxide (iNO) is being increasingly used in preterm infants < 34 weeks with hypoxemic respiratory failure (HRF) and/or pulmonary hypertension (PH). Objective To evaluate the risk factors, survival characteristics, and lung histopathology in preterm infants with PH/HRF. Methods Retrospective chart review was conducted to determine characteristics of 93 preterm infants treated with iNO in the first 28 days and compared with 930 matched controls. Factors associated with survival with preterm HRF and smooth muscle actin from nine autopsies were evaluated. Results Preterm neonates treated with iNO had a higher incidence of preterm prolonged rupture of membrane (pPROM ≥ 18 hours), oligohydramnios and delivered by C-section. In infants treated with iNO, antenatal steroids (odds ratio [OR],3.7; confidence interval [CI], 1.2-11.3; p = 0.02), pPROM (OR, 1.001; CI, 1.0-1.004; p = 0.3), and oxygenation response to iNO (OR, 3.7; CI, 1.08-13.1; p = 0.037) were associated with survival. Thirteen infants with all three characteristics had 100% (13/13) survival without severe intraventricular hemorrhage (IVH)/periventricular leukomalacia (PVL) compared with 48% survival (12/25, p = 0.004) and 16% severe IVH/PVL without any of these factors. Severity of HRF correlated with increased smooth muscle in pulmonary vasculature. Conclusion Preterm infants with HRF exposed to antenatal steroids and pPROM had improved oxygenation with iNO and survival without severe IVH/PVL. Precisely targeting this subset may be beneficial in future trials of iNO.