Prolonged rupture of membranes and pulmonary hypoplasia in very preterm infants: pathophysiology and guided treatment

Predicting Clinical Outcomes of Severe Bronchopulmonary Dysplasia through New Definitions and Phenotypes

This study aimed to compare the accuracy of three newly proposed definitions of bronchopulmonary dysplasia (BPD) in predicting outcomes, and to investigate the impact of large airway versus parenchymal versus vascular BPD phenotypes on BPD outcomes.Retrospective chart review of 100 infants with severe BPD discharged from a Children's hospital between 2020 and 2021. Multivariable models evaluated the associations between BPD definitions and phenotypes with tracheostomy and death at 6 months and 1 year after NICU discharge. Secondary outcomes included the need for respiratory support, the use of pulmonary medications, and the need for long-term gastrostomy feeding.Neonatal research network (NRN) and BPD collaborative criteria best-predicted outcomes associated with tracheostomy and/or death (p < 0.001). Among the three BPD phenotypes, large airway disease was independently associated with death or tracheostomy (odds ratios [OR]: 10.5; 95% confidence interval [CI]: 1.6, 68.1). The combination of all three phenotypes was also associated with death or tracheostomy (OR: 9.8; 95% CI: 1.0, 93.5). Both NRN and BPD collaborative definitions showed an association with the need for respiratory support, medication use, and need for long-term gastrostomy tube feeding. Among the 29 infants for whom complete information was available, 18 (62%), 20 (69%), and 18 (62%) had parenchymal, central airway and pulmonary vascular phenotype, respectively.Our results indicate that newer definitions of BPD may better predict the severity of BPD and the need for long-term invasive ventilation support compared with the 2001 National Institute of Health definition of BPD phenotypes impacting mortality and short-term outcomes. These data may be useful for counseling families and developing phenotype-based individualized treatment plans. · The current definition of BPD has limitations.. · New definitions of BPD better predict outcomes.. · BPD phenotypes can better predict outcomes..

Outcomes of extremely preterm infants exposed to prolonged prelabor rupture of membranes before 24 weeks of gestation

BACKGROUND

Preterm prelabor rupture of membranes before or around the limit of fetal viability is associated with serious maternal and neonatal complications, including chorioamnionitis, extremely preterm birth, and pulmonary hypoplasia.

OBJECTIVE

This study aimed to describe the contemporary outcomes of extremely preterm infants born after prolonged periviable preterm prelabor rupture of membranes and to identify perinatal factors associated with survival and survival without severe neurodevelopmental impairment.

STUDY DESIGN

Among actively treated infants born alive at <27 weeks' gestational age in centers of the Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network from 2012 to 2018, the outcomes of survival and survival without severe neurodevelopmental impairment at 22 to 26 months' corrected age were compared between infants exposed to prolonged (≥120 hours) periviable (<24 weeks' gestational age) preterm prelabor rupture of membranes and unexposed infants born after rupture of membranes ≤18 hours before delivery or at delivery with adjustment for birth gestational age, sex, multiple gestation, antenatal steroids, small for gestational age, insurance, and center. Regression models were used to identify perinatal factors associated with survival and survival without severe neurodevelopmental impairment among the infants exposed to prolonged periviable preterm prelabor rupture of membranes.

RESULTS

The analysis included 609 infants exposed to prolonged periviable preterm prelabor rupture of membranes and 4489 unexposed infants. In the prolonged periviable preterm prelabor rupture of membranes group, 444 of 608 (73%) infants survived and 298 of 533 (56%) infants survived without severe neurodevelopmental impairment. The odds of survival (odds ratio, 0.84; 95% confidence interval, 0.68-1.05) and survival without severe neurodevelopmental impairment (odds ratio, 0.91; 95% confidence interval, 0.75-1.12) were not significantly different between prolonged periviable preterm prelabor rupture of membranes and unexposed groups. The variables associated with higher odds of survival without severe neurodevelopmental impairment were later gestational age at birth (odds ratio, 1.37; 95% confidence interval, 1.13-1.67), later gestational age at preterm prelabor rupture of membranes (odds ratio, 1.44; 95% confidence interval, 1.26-1.63), and female sex (odds ratio, 1.57; 95% confidence interval, 1.06-2.34), whereas small-for-gestational-age infants had lower odds of survival without severe neurodevelopmental impairment (odds ratio, 0.14; 95% confidence interval, 0.04-0.51).

CONCLUSION

The odds of survival and survival without severe neurodevelopmental impairment among infants exposed to prolonged periviable preterm prelabor rupture of membranes were not significantly different from those of unexposed infants but decreased with earlier gestational age at birth and rupture of membranes.

Delivery room and early postnatal management of neonates with congenital heart disease

Advancements in prenatal detection have improved postnatal outcomes for patients with congenital heart disease (CHD). Detailed diagnosis during pregnancy allows for preparation for the delivery and immediate postnatal care for the newborns with CHD. Most CHDs do not result in hemodynamic instability at the time of birth and can be stabilized following the guidelines of the neonatal resuscitation program (NRP). Critical CHD that requires intervention immediately after birth is recommended to be delivered in facilities where immediate neonatal and cardiology care can be provided. Postnatal stabilization and resuscitation for these defects warrant deviation from the standardized NRP. For neonatal providers, knowing the diagnosis of fetal CHD allows for preparation for the anticipated instability in the delivery room. Prenatal detection fosters collaboration between fetal cardiology, cardiology specialists, obstetrics, and neonatology, improving outcomes for neonates with critical CHD.

Mechanical ventilation in special populations

Optimal respiratory support can only be achieved if the ventilator strategy utilized for each individual patient at any given point in the evolution of their disease process is tailored to the underlying pathophysiology. The critically ill newborn infant requires individualized patient care when it comes to mechanical ventilation. This can only occur if the clinician has a good understanding of the different pathophysiologies of a variety of conditions that can lead to respiratory failure. In this chapter we describe the key pathophysiological features of bronchopulmonary dysplasia, meconium aspiration syndrome and lung hypoplasia syndromes with emphasis on congenital diaphragmatic hernia. We review available evidence to guide management an provide specific recommendations for pathophysiologically-based mechanical ventilation support.

Bilateral lung transplantation during pregnancy after ECMO for influenza-A caused ARDS

Pregnant women with influenza-A have an increased risk of developing acute respiratory distress syndrome (ARDS). Extracorporeal membrane oxygenation (ECMO) can be used as salvage therapy, with lung transplantation as a therapeutic option. However, successful bilateral lung transplantation during pregnancy has never been reported before. We herein report the case of a 34-year-old primipara, who was diagnosed with ARDS caused by influenza-A-induced pneumonia at early gestation. After considering all possible therapeutic options and being fully dependent on VV-ECMO support, she underwent bilateral lung transplantation. The transplantation with intraoperative central VA-ECMO support was successfully performed with good recovery after an initial primary graft dysfunction. The pregnancy was prolonged until 29⁺⁵  gestational weeks. The newborn exhibited growth retardation and was initially stabilized, but later died due to severe, hypoxic respiratory failure and pulmonary hypertension. In conclusion, lung transplantation is a possible salvage therapy for patients with severe lung failure following ARDS during pregnancy. However, it places the mother and unborn child at risk. A multi-professional approach is warranted to diagnose and treat complications at an early stage.

Early pulmonary hypertension is a risk factor for bronchopulmonary dysplasia-associated late pulmonary hypertension in extremely preterm infants

This study evaluated whether early pulmonary hypertension (PH) in extremely preterm infants (EPIs) at 22–27 weeks of gestation detected clinically with echocardiography at 4–7 postnatal days (PND) is a risk factor for death before 36 weeks post-menstrual age (PMA) or late PH in moderate or severe (m/s) bronchopulmonary dysplasia (BPD) (BPD-PH). We analyzed risk factors for death before 36 weeks PMA or BPD-PH. Among 247 EPIs enrolled, 74 (30.0%) had early PH. Twenty-one (28.4%) infants with early PH and 18 (10.4%) without early PH died before 36 weeks PMA; 14 (18.9%) infants with early PH and 9 (5.2%) without early PH had BPD-PH at 36–38 weeks PMA. Multivariate analysis revealed that early PH (adjusted odds ratio, 6.55; 95% confidence interval, 3.10–13.82, P < 0.05), clinical chorioamnionitis (2.50; 1.18–5.31), intraventricular hemorrhage (grade 3–4) (3.43; 1.26–9.37), and late sepsis (6.76; 3.20–14.28) independently increased the risk of development of death before 36 weeks PMA or BPD-PH. Subgroup analysis among m/s BPD patients revealed that early PH (4.50; 1.61–12.58) and prolonged invasive ventilator care (> 28 days) (4.91; 1.02–23.68) increased the risk for late PH independently. In conclusion, EPIs with early PH at 4–7 PND should be monitored for BPD-associated late PH development.

Increase in the use of inhaled nitric oxide in neonatal intensive care units in England: a retrospective population study

OBJECTIVE

To describe temporal changes in inhaled nitric oxide (iNO) use in English neonatal units between 2010 and 2015.

DESIGN

Retrospective analysis using data extracted from the National Neonatal Research Database.

SETTING

All National Health Service neonatal units in England.

PATIENTS

Infants of all gestational ages born 2010-2015 admitted to a neonatal unit and received intensive care.

MAIN OUTCOME MEASURES

Proportion of infants who received iNO; age at initiation and duration of iNO use.

RESULTS

4.9% (6346/129 883) of infants received iNO; 31% (1959/6346) were born <29 weeks, 18% (1152/6346) 29-33 weeks and 51% (3235/6346)>34 weeks of gestation. Between epoch 1 (2010-2011) and epoch 3 (2014-2015), there was (1) an increase in the proportion of infants receiving iNO: <29 weeks (4.9% vs 15.9%); 29-33 weeks (1.1% vs 4.8%); >34 weeks (4.5% vs 5.0%), (2) increase in postnatal age at iNO initiation: <29 weeks 10 days vs 18 days; 29-33 weeks 2 days vs 10 days, (iii) reduction in iNO duration: <29 weeks (3 days vs 2 days); 29-33 weeks (2 days vs 1 day).

CONCLUSIONS

Between 2010 and 2015, there was an increase in the use of iNO among infants admitted to English neonatal units. This was most notable among the most premature infants with an almost fourfold increase. Given the cost of iNO therapy, limited evidence of efficacy in preterm infants and potential for harm, we suggest that exposure to iNO should be limited, ideally to infants included in research studies (either observational or randomised placebo-controlled trial) or within a protocolised pathway. Development of consensus guidelines may also help standardise practice.

Neonatal and Childhood Outcomes Following Preterm Premature Rupture of Membranes

Preterm premature rupture of membranes (PPROM) is almost uniformly associated with preterm birth and thus sequelae of prematurity explain many of the complications associated with this condition. However, the unique inflammatory environment and oligohydramnios associated with PPROM may impart unique neonatal and childhood morbidity compared with other preterm birth pathways.

Neonatal outcome comparisons between preterm infants with or without early pulmonary hypertension following prolonged preterm premature rupture of membranes before 25 gestational weeks in Korean Neonatal Network

Objective: To determine the outcomes of very low birth weight infants (VLBWIs) following maternal mid-trimester prolonged preterm premature rupture of membranes (PPROM) and subsequent early pulmonary hypertension (PH).Design: Prospective cohort study.Setting: A nationwide web-based registry of VLBWIs from 67 neonatal intensive care units.Patients: VLBWIs registered on the Korean Neonatal Network and born between 23 and 34 gestational weeks.Methods: VLBWIs exposed to maternal PPROM prior to 25 gestational weeks and lasting ≥7 days (PPROM25, n = 402) were matched 1:1 with infants not exposed or exposed within 24 h to PPROM (CON, n = 402), using propensity score matching. The PPROM25 group was subdivided into PPROM25 groups with or without early PH, defined as exposure to inhaled nitric oxide or other pulmonary vasodilators to treat PH within 3 days of life. Clinical variables and major outcomes were compared, and risk factors for mortality and morbidities were analyzed.Results: Of 1790 infants with maternal PPROM, the PPROM25 group comprised 402 (22.5%) infants. Survival rates were similar between the CON and PPROM25 groups (71.6% vs 74.4%); however, the incidence of bronchopulmonary dysplasia (BPD) differed (47.8% and 60.2%, p < .05). Infants in the PPROM25 group with early PH had higher mortality (55.6%) and more severe intraventricular hemorrhage (IVH) (31.7%) than infants in the PPROM25 group without early PH (21.9% and 14.3%, respectively; p < .05). In multivariate analysis, lower 5 min Apgar score and the presence of oligohydramnios increased the risk of development of early PH. The presence of PPROM25 was founded to be a significant risk factor for BPD and early PH in relation to mortality and severe IVH, respectively.Conclusions: In VLBWIs, prolonged exposure to maternal mid-trimester PPROM increased the risk of BPD. Subsequent early PH immediately after birth increased mortality and severe IVH, thus, requires special attention.

Delivery room emergencies: Respiratory emergencies in the DR

The majority of newborns transition to extra uterine life without support. However, respiratory emergencies in the delivery room are a common occurrence. Whilst some situations are predictable e.g. the anticipated birth of an extremely preterm infant, others are less so. In this chapter we address the most frequent scenarios that result in delivery room respiratory emergencies and discuss the latest recommendations for their management. We outline the need for a trained resuscitation team and appropriate equipment to provide respiratory support at every birth. We address the basic care that all infants should receive, the detailed application of non-invasive ventilation and the use of advanced airway techniques. We discuss the unique challenges presented by extreme prematurity including umbilical cord management, use of supplemental oxygen, initial modes of respiratory support and surfactant delivery. We will explore optimal techniques in the management of infants with lung hypoplasia, pneumothorax and meconium aspiration.

Point of care ultrasound in the neonatal unit: Applications, training and accreditation

Point-of-care, or clinician-performed ultrasound (CPU), is increasingly utilised within neonatology as a valuable adjunct to clinical examination. The ability to perform and interpret rapid, real-time, serial assessment of patient physiology at the bedside has seen the potential uses of CPU expand, with an evolving list of clinical and research applications. Benefits of functional assessment of neonatal haemodynamics in particular have been described across a range of gestational ages and disease states. Devising suitable curricula for trainees and ensuring robust processes for the training and credentialing of clinicians performing CPU is essential. Challenges to universal implementation of CPU in the neonatal intensive care setting exist, and regional differences in training and accreditation are well described. Appropriate integration into clinical decision-making and ensuring competency-based locally appropriate training programs, which build on an expanding evidence base, are key priorities in ensuring newborns receive optimal benefit from the modality.

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.

Performance indices of AmnioQuick Duo+ versus placental α-microglobulin-1 tests for women with prolonged premature rupture of membranes

OBJECTIVE

To compare AmnioQuick Duo+ versus the placental α-microglobulin-1 (PAMG-1) test for diagnosis of prolonged premature rupture of membranes (PROM).

METHODS

A multicenter prospective cohort study included women with suspected PROM at six tertiary institutions in southern Nigeria between January 1 and December 31, 2015. The inclusion criteria were features of PROM lasting at least 24 hours and a pregnancy duration of more than 24 weeks. AmnioQuick Duo+ (Biosynex, Strasbourg, France) and PAMG-1 (AmniSure International, Boston, USA) tests were used to diagnose PROM, which was confirmed after delivery by any two of the following criteria: delivery within 48 hours to 7 days, chorioamnionitis, membranes perceptibly ruptured at delivery, and adverse perinatal outcomes considerably associated with prolonged PROM.

RESULTS

Of 100 women assessed for eligibility, 99 were included. Sensitivity, specificity, and accuracy were, respectively, 97.3%, 100%, and 95.9% for AmnioQuick Duo+, and 93.2%, 100%, and 90.4% for PAMG-1. The differences were not significant and the diagnostic discordant rate between the two tests was 3.1%. In equivocal cases (i.e., negative pooling test result), AmnioQuick Duo+ and PAMG-1 performed equally (diagnostic accuracy, 100% vs 97.7%; P>0.99).

CONCLUSION

For diagnosis of PROM, AmnioQuick Duo+ was found to be non-inferior and comparable in accuracy to the PAMG-1 test, with a diagnostic discordance rate of 3.1%.

Outcomes of hypoxic respiratory failure at birth associated with previable rupture of membranes

OBJECTIVE

To characterize clinical outcomes of infants born after previable rupture of membranes (pROM, < 23 weeks gestation and latency period ≥ 2 weeks) in relation to refractory hypoxic respiratory failure (rHRF).

STUDY DESIGN

pROM neonates categorized as rHRF (FiO₂ > 0.6 for ≥ 2 h) and treated (high frequency ventilation + inhaled nitric oxide) were compared with no rHRF group. Primary outcome was survival until discharge. Factors associated with rHRF and mortality were identified.

RESULT

Overall, mortality and disability rates were 28% and 22%, respectively. Treated rHRF group (n = 32) had longer period of ROM, mortality was (31% vs. 14%; p = 0.20), with similar survival-without-disability (54% vs. 47%; p = 0.67). Higher gestational age at birth [1.57 (1.03,2.39)] and cesarean delivery [12.6 (1.22,125)] were associated with increased survival.

CONCLUSION

Birth after pROM is associated with high rates of adverse outcomes, independent of latency period. Following treatment, rHRF infants may have similar long-term outcomes as those without rHRF.

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.

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.

Prolonged respiratory disorder predicts adverse prognosis in infants with end-stage kidney disease

BACKGROUND

Among comorbidities, pulmonary hypoplasia (PH) is known as a significant risk factor for mortality in infants with end-stage kidney disease (ESKD). However, the final outcomes of infants with both ESKD and PH are still not well defined, as the diagnosis modality, and definition of PH severity remain ambiguous.

METHODS

Children initiating peritoneal dialysis during infancy from 1990 to 2015 were followed until death, date of last contact, or the end of 2015. We examined the long-term outcome of children with congenital pulmonary disorders by studying infants with prolonged respiratory disorders of greater than 28 days duration after birth and evaluated risk factors for mortality.

RESULTS

Forty-six children were followed (median follow-up, 9.23 years), and classified as children without (n = 38; Group A) or with (n = 8; Group B) a prolonged respiratory disorder. Overall actuarial 5 year survival rate in this cohort was 79.5 %. The survival curve in Group B showed a significant decline compared with Group A. Prolonged respiratory disorder was significantly associated with mortality by multivariate analysis (hazard ratio, 8.32).

CONCLUSIONS

Infants who initiate peritoneal dialysis complicated by prolonged respiratory disorders have increased adverse risk factors for mortality; therefore, withholding aggressive treatment should be considered.

Management of hypoxemic respiratory failure and pulmonary hypertension in preterm infants

While diagnoses of hypoxemic respiratory failure (HRF) and pulmonary hypertension (PH) in preterm infants may be based on criteria similar to those in term infants, management approaches often differ. In preterm infants, HRF can be classified as 'early' or 'late' based on an arbitrary threshold of 28 postnatal days. Among preterm infants with late HRF, the pulmonary vascular abnormalities associated with bronchopulmonary dysplasia (BPD) represent a therapeutic challenge for clinicians. Surfactant, inhaled nitric oxide (iNO), sildenafil, prostacyclin and endothelin receptor blockers have been used to manage infants with both early and late HRF. However, evidence is lacking for most therapies currently in use. Chronic oral sildenafil therapy for BPD-associated PH has demonstrated some preliminary efficacy. A favorable response to iNO has been documented in some preterm infants with early PH following premature prolonged rupture of membranes and oligohydramnios. Management is complicated by a lack of clear demarcation between interventions designed to manage respiratory distress syndrome, prevent BPD and treat HRF. Heterogeneity in clinical phenotype, pathobiology and genomic underpinnings of BPD pose challenges for evidence-based management recommendations. Greater insight into the spectrum of disease phenotypes represented by BPD can optimize existing therapies and promote development of new treatments. In addition, better understanding of an individual's phenotype, genotype and biomarkers may suggest targeted personalized interventions. Initiatives such as the Prematurity and Respiratory Outcomes Program provide a framework to address these challenges using genetic, environmental, physiological and clinical data as well as large repositories of patient samples.

Advances in Neonatal Pulmonary Hypertension

Persistent pulmonary hypertension of the newborn (PPHN) is a surprisingly common event in the neonatal intensive care unit, and affects both term and preterm infants. Recent studies have begun to elucidate the maternal, fetal and genetic risk factors that trigger PPHN. There have been numerous therapeutic advances over the last decade. It is now appreciated that oxygen supplementation, particularly for the goal of pulmonary vasodilation, needs to be approached as a therapy that has risks and benefits. Administration of surfactant or inhaled nitric oxide (iNO) therapy at a lower acuity of illness can decrease the risk of extracorporeal membrane oxygenation/death, progression of disease and duration of hospital stay. Milrinone may have specific benefits as an 'inodilator', as prolonged exposure to iNO plus oxygen may activate phosphodiesterase (PDE) 3A. Additionally, sildenafil and hydrocortisone may benefit infants exposed to hyperoxia and oxidative stress. Continued investigation is likely to reveal new therapies such as citrulline and cinaciguat that will enhance NO synthase and soluble guanylate cyclase function. Continued laboratory and clinical investigation will be needed to optimize treatment and improve outcomes.