Controversies in the identification and management of acute pulmonary hypertension in preterm neonates

First-year outcomes of very low birth weight preterm singleton infants with hypoxemic respiratory failure treated with milrinone and inhaled nitric oxide (iNO) compared to iNO alone: A nationwide retrospective study

BACKGROUND

Inhaled nitric oxide (iNO) has a beneficial effect on hypoxemic respiratory failure. The increased use of concurrent iNO and milrinone was observed. We aimed to report the trends of iNO use in the past 15 years in Taiwan and compare the first-year outcomes of combining iNO and milrinone to the iNO alone in very low birth weight preterm (VLBWP) infants under mechanical ventilation.

METHODS

This nationwide cohort study enrolled preterm singleton infants with birth weight <1500g treated with iNO from 2004 to 2019. Infants were divided into two groups, with a combination of intravenous milrinone (Group 2, n = 166) and without milrinone (Group 1, n = 591). After propensity score matching (PSM), each group's sample size is 124. The primary outcomes were all-cause mortality and the respiratory condition, including ventilator use and duration. The secondary outcomes were preterm morbidities within one year after birth.

RESULTS

After PSM, more infants in Group 2 needed inotropes. The mortality rate was significantly higher in Group 2 than in Group 1 from one month after birth till 1 year of age (55.1% vs. 13.5%) with the adjusted hazard ratio of 4.25 (95%CI = 2.42-7.47, p <0.001). For infants who died before 36 weeks of postmenstrual age (PMA), Group 2 had longer hospital stays compared to Group 1. For infants who survived after 36 weeks PMA, the incidence of moderate and severe bronchopulmonary dysplasia (BPD) was significantly higher in Group 2 than in Group 1. For infants who survived until one year of age, the incidence of pneumonia was significantly higher in Group 2 (28.30%) compared to Group 1 (12.62%) (p = 0.0153).

CONCLUSION

Combined treatment of iNO and milrinone is increasingly applied in VLBWP infants in Taiwan. This retrospective study did not support the benefits of combining iNO and milrinone on one-year survival and BPD prevention. A future prospective study is warranted.

Intertemporal Improvement in Physicians' Perceptions of the Short-Term Adverse Outcomes of Neonatal Pain: Results of a Two-Time-Point National Survey

Pain in early life may seriously impact neonatal outcomes. This study aimed to evaluate whether the perceptions of physicians working in neonatal intensive care units (NICUs) of the short-term adverse outcomes associated with neonatal pain have changed over a 20-year period. Self-administered questionnaires were distributed to 117 and 145 neonatologists, pediatricians, and fellows working in level III NICUs in 2000 (T1) and 2019 (T2), respectively. The questionnaire consisted of four domains, including the central nervous, cardiovascular, and respiratory systems, as well as "other systems" (metabolic/endocrine system, growth, and general condition), with 21 total items overall. Although the proportion of positive (correct) responses to the total and system-specific domain scores was significantly higher at T2 than T1, the knowledge of certain short-term adverse outcomes was suboptimal even at T2. Adjustment for cofactors confirmed the independent association of the survey time-point with the total and system-specific domain scores. Moreover, NICU type was an independent significant factor associated with the adjusted total and central nervous system scores, while young doctors had a better knowledge of adverse cardiovascular effects. Conclusions: The perceptions of NICU physicians concerning the short-term outcomes associated with neonatal pain have significantly improved over the past 20 years, although remaining knowledge gaps mandate ongoing efforts to achieve an improvement in neonatal care.

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.

Haemodynamic assessment and management of hypotension in the preterm

The management of low blood flow states in premature neonates is fraught with many challenges. We remain over-reliant on regimented stepwise protocols that use mean blood pressure as a threshold for intervention to guide treatment, without giving due consideration to the underlying pathophysiology. The current available evidence does not reflect the need to concentrate on the unique pathophysiology of the preterm infant and thus leads to widespread misuse of vasoactive agents that often do not provide the desired clinical effect. Therefore, understanding the underlying pathophysiological underpinnings of haemodynamic compromise may better guide choice of agent and assess physiological response to the selected intervention.

Pulmonary hypertension among preterm infants born at 22 through 32 weeks gestation in France: Prevalence, survival, morbidity and management in the EPIPAGE-2 cohort study

OBJECTIVE

To determine the prevalence, short-term prognosis and pharmacologic management of pulmonary hypertension (PH) among very preterm infants born before 32 weeks gestation (WG).

STUDY DESIGN

In the EPIPAGE-2 French national prospective population-based cohort of preterm infants born in 2011, those presenting with PH were identified and prevalence was estimated using multiple imputation. The primary outcome was survival without severe morbidity at discharge and was compared between infants with or without PH after adjusting for confounders, using generalized estimating equations models. Subgroup analysis was performed according to gestational age (GA) groups.

RESULTS

Among 3383 eligible infants, 3222 were analyzed. The prevalence of PH was 6.0 % (95 % CI, 5.2-6.9), 14.5 % in infants born at 22-27+6 WG vs 2.7 % in infants born at 28-31+6 WG (P < .001). The primary outcome (survival without severe morbidity at discharge) occurred in 30.2 % of infants with PH vs 80.2 % of infants without PH (P < .001). Adjusted incidence rate ratios for survival without severe morbidity among infants with PH were 0.42 (0.32-0.57) and 0.52 (0.39-0.69) in infants born at 22-27+6 weeks gestation and those born at 28-31+6 weeks, respectively. Among infants with PH, 92.2 % (95 % CI, 87.7-95.2) received sedation and/or analgesia, 63.5 % (95 % CI, 56.6-69.9) received inhaled NO and 57.6 % (95 % CI, 50.9-64.0) received hemodynamic treatments.

CONCLUSION

In this population-based cohort of very preterm infants, the prevalence of PH was 6 %. PH was associated with a significant decrease of survival without severe morbidity in this population.

Diseases associated with prematurity in correlation with N-terminal pro-brain natriuretic peptide levels during the early postnatal life

The aim of this observational study was to investigate the influence of different typical preterm diseases on NT-proBNP serum levels in the early postnatal period of life of a preterm infant. NT-proBNP levels of 118 preterm infants born ≤ 31 weeks GA were determined at the first week of life, after 4 ± 1 weeks of life, and at a corrected gestational age of 36 + 2 weeks. Relevant complications with a possible influence on NT-proBNP values in the first week of life such as early neonatal infection, hemodynamically significant PDA (hsPDA), early pulmonary hypertension (early PH), and intraventricular hemorrhage (IVH) were evaluated; at 4 ± 1 weeks of life, bronchopulmonary dysplasia (BPD), BPD-related pulmonary hypertension (BPD-associated PH), late infection, IVH, and intestinal complications were evaluated. At a corrected gestational age of 36 ± 2 weeks, we examined the effect of retinopathy of prematurity (ROP), BPD, BPD-associated PH, and late infection on NT-proBNP levels. In the first days of life, only the isolated occurrence of hsPDA resulted in significantly increased NT-proBNP levels. In multiple linear regression analysis, early infection remained independently associated with NT-proBNP levels. At 4 ± 1 weeks of age, the isolated presence of BPD and BPD-related PH resulted in increased levels, and the effect remained significant in the multiple regression analysis. At a corrected gestational age of 36 ± 2 weeks, infants with relevant complications at this final evaluation time tended to have lower NT-proBNP values than our exploratory reference values.    Conlusion: NT-proBNP in the first week of life seems to be mainly influenced by an hsPDA and infection or inflammation. BPD and BPD-related PH are the most important factors influencing NT-proBNP serum levels in the first month of life. When preterm infants reach a corrected GA of 36 ± 2 weeks, chronological age rather than complications of prematurity must be considered when interpreting NT-proBNP levels. What is Known: • Several complications associated with prematurity, such as hemodynamically significant PDA, pulmonary hypertension, bronchopulmonary dysplasia, and retinopathy of prematurity, have been shown to influence NT-proBNP levels in preterm infants in their early postnatal life. What is New: • Hemodynamically relevant PDA is a major factor in the increase of NT-proBNP levels in the first week of life. • Bronchopulmonary dysplasia and pulmonary hypertension associated with bronchopulmonary dysplasia are important factors in the increase in NT-proBNP levels in preterm infants at approximately 1 month of age.

Response categorization and outcomes in extremely premature infants born at 22-26 weeks gestation that received inhaled nitric oxide for hypoxic respiratory failure

OBJECTIVE

To evaluate the outcomes of extremely premature infants who received inhaled nitric oxide(iNO) for hypoxic respiratory failure(HRF).

STUDY DESIGN

Retrospective analysis of 107 infants born 22-26 weeks gestation who received iNO for HRF at a single institution. Infants were categorized as positive, negative, or no responders based on change in FiO2 or OI. Underlying physiology was determined using Echocardiography/Radiography/Biochemistry.

RESULTS

63% of infants had a positive response; they received iNO earlier and were more likely to have acute pulmonary hypertension(PH). Positive response correlated with decreased incidence of death or grade 3 BPD at 36 weeks postmenstrual age, as compared to a negative response.

CONCLUSIONS

Extremely premature infants have a positive response rate to iNO comparable to term infants when used for PH in the transitional period. Infants with a negative response to iNO had worse outcomes, necessitating the determination of the underlying physiology of HRF prior to iNO initiation.

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

AIM

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

Management of cardiac dysfunction in neonates with pulmonary hypertension and the role of the ductus arteriosus

Pulmonary hypertension in the neonate is associated with cardiopulmonary disturbances and neurodevelopment morbidity. The patent ductus arteriosus is a persistent fetal shunt that can be pathologic vs supportive in the setting of neonatal pulmonary hypertension. Understanding the underlying pathophysiology of pulmonary hypertension and the cardiopulmonary effects of various phenotypes can guide management in this vulnerable population. In this narrative, we will summarize the physiologic principles of pulmonary hypertension, the impact of the patent ductus arteriosus on various phenotypes, and the utility of serial targeted neonatal echocardiography to individualize clinical assessment and management.

Group 3 Pulmonary Hypertension: From Bench to Bedside

Pulmonary hypertension (PH) because of chronic lung disease is categorized as Group 3 PH in the most recent classification system. Prevalence of these diseases is increasing over time, creating a growing need for effective therapeutic options. Recent approval of the first pulmonary arterial hypertension therapy for the treatment of Group 3 PH related to interstitial lung disease represents an encouraging advancement. This review focuses on molecular mechanisms contributing to pulmonary vasculopathy in chronic hypoxia, the pathology and epidemiology of Group 3 PH, the right ventricular dysfunction observed in this population and clinical trial data that inform the use of pulmonary vasodilators in Group 3 PH.

Cardiorespiratory management of infants born at 22 weeks' gestation: The Iowa approach

The approach to clinical care of infants born at 22 weeks' gestation must be consistent and well-designed if optimal results are to be expected. Publications from several international centers have demonstrated that, although there may be variance in aspects of care in this vulnerable population, treatment should be neither random nor inconsistent. In designing a standardized approach, careful attention should be paid to the unique anatomy, physiology, and biochemistry of this vulnerable patient population. Emerging evidence, suggesting a link between cardiopulmonary health and longer-term sequela, highlights the importance of understanding the relationship between cardiorespiratory illnesses of the 22-week infant, treatments provided, and subsequent cardiopulmonary development. In this review we will provide an overview to our approach to cardiopulmonary assessment and treatment, with a particular emphasis on the importance of early recognition of atypical phenotypes, timely interventions with evidence-based treatments, and longitudinal monitoring.

Care of the critically ill neonate with hypoxemic respiratory failure and acute pulmonary hypertension: framework for practice based on consensus opinion of neonatal hemodynamics working group

Circulatory transition after birth presents a critical period whereby the pulmonary vascular bed and right ventricle must adapt to rapidly changing loading conditions. Failure of postnatal transition may present as hypoxemic respiratory failure, with disordered pulmonary and systemic blood flow. In this review, we present the biological and clinical contributors to pathophysiology and present a management framework.

Hemodynamic dysfunction in neonatal sepsis

Cardiovascular disturbances are a frequent occurrence in neonatal sepsis. Preterm and term infants are particularly vulnerable due to the unique features of their cardiovascular function and reserve, compared to older children and adults. The clinical manifestations of neonatal sepsis are a product of the variable inflammatory pathways involved (warm vs. cold shock physiology), developmental state of the cardiovascular system, and hormonal responses. Targeted neonatal echocardiography has played an important role in advancing our knowledge, may help delineate specific hemodynamic phenotypes in real-time, and supports an individualized physiology-based management of sepsis-associated cardiovascular dysfunction. IMPACT: Cardiovascular dysfunction is a common sequela of sepsis. This review aims to highlight the pathophysiological mechanisms involved in hemodynamic disturbance in neonatal sepsis, provide insights from targeted neonatal echocardiography-based clinical studies, and suggest its potential incorporation in day-to-day management.

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.

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.

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

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

Respiratory Severity Score with Regard to Birthweight during the Early Days of Life for Predicting Pulmonary Hypertension in Preterm Infants

OBJECTIVE

The respiratory severity score (RSS) has been demonstrated to be associated with the oxygenation index in intubated newborn infants. We aimed to evaluate the usefulness of RSS with regard to birthweight (BW) in preterm infants for predicting an association with future pulmonary hypertension (PH).

METHODS

Preterm infants with <30 weeks' gestation and <1250 g BW were reviewed and grouped into two (PH vs. no PH). Basic perinatal characteristics, comorbidities and parameters reflecting lung condition, including duration of invasive mechanical ventilator care, were compared. Respiratory support parameters (FiO2, RSS and RSS/kg) during the first 5 days of birth (0-120 h) were compared between the groups, and receiver operating characteristics curves were produced to evaluate the association with PH.

RESULTS

RSS/kg, of the three respiratory support parameters, demonstrated significantly higher values in the PH group in the early days of life. Particularly, RSS/kg at day 2 of life had the greatest area under the curve [0.762, 95% confidence interval (CI) 0.655-0.869, p < 0.001] and maintained statistical significance [odds ratio (OR) 1.352, 95% CI 1.055-1.732, p = 0.017] in the multivariable analysis for a potential association with PH, along with gestational age (OR 0.996, 95% CI 0.993-0.999, p = 0.015) and preterm premature rupture of membrane >18 h (OR 4.907, 95% CI 1.436-16.765, p = 0.011).

CONCLUSION

RSS/kg is a potential marker associated with the development of PH. Future studies could verify its usefulness as a reliable surrogate for predicting respiratory morbidity in clinical settings.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Updates on Management for Acute and Chronic Phenotypes of Neonatal Pulmonary Hypertension

Neonatal pulmonary hypertension is a heterogeneous disease in term and preterm neonates. It is characterized by persistent increase of pulmonary artery pressures after birth (acute) or an increase in pulmonary artery pressures after approximately 4 weeks of age (chronic); both phenotypes result in exposure of the right ventricle to sustained high afterload. In-depth clinical assessment plus echocardiographic measures evaluating pulmonary blood flow, pulmonary vascular resistance, pulmonary capillary wedge pressure, and myocardial contractility are needed to determine the cause and provide individualized targeted therapies. This article summarizes the causes, risk factors, hemodynamic assessment, and management of neonatal pulmonary hypertension.

Phenotypes of Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is the most common chronic morbidity in preterm infants. In the absence of effective interventions, BPD is currently a major therapeutic challenge. Several risk factors are known for this multifactorial disease that results in disrupted lung development. Inflammation plays an important role and leads to persistent airway and pulmonary vascular disease. Since corticosteroids are potent anti-inflammatory agents, postnatal corticosteroids have been used widely for BPD prevention and treatment. However, the clinical responses vary to a great degree across individuals, and steroid-related complications remain major concerns. Emerging studies on the molecular mechanism of lung alveolarization during inflammatory stress will elucidate the complicated pathway and help discover novel therapeutic targets. Moreover, with the advances in metabolomics, there are new opportunities to identify biomarkers for early diagnosis and prognosis prediction of BPD. Pharmacometabolomics is another novel field aiming to identify the metabolomic changes before and after a specific drug treatment. Through this "metabolic signature," a more precise treatment may be developed, thereby avoiding unnecessary drug exposure in non-responders. In the future, more clinical, genetic, and translational studies would be required to improve the classification of BPD phenotypes and achieve individualized care to enhance the respiratory outcomes in preterm infants.

Variation in the definition of pulmonary hypertension and clinical indications for the use of nitric oxide in neonatal clinical trials

AIM

Pulmonary hypertension (PH) frequently complicates neonatal hypoxaemic respiratory failure, but is inconsistently defined. We aimed to describe the variation among randomised controlled trials (RCTs) of inhaled nitric oxide (iNO), in relation to the definition of PH and/or hypoxaemic respiratory failure used to select patients for trial inclusion.

METHODS

PubMed, Cochrane Library and ClinicalTrials.gov were systematically searched for RCTs of iNO in neonates. Included studies were assessed for clinical and/or echocardiography criteria used to define PH/hypoxaemic respiratory failure.

RESULTS

Thirty-two trials were included in this review, of which 23 enrolled infants ≥34 weeks' gestation. Echocardiographic diagnosis was used in 21 studies, but there was considerable variation in the echocardiographic parameters used to diagnose PH. The most commonly used indices included markers of tricuspid regurgitation and extrapulmonary shunt.

CONCLUSION

There is wide variation in the definition of PH used to select infants for inclusion into RCTs of iNO therapy in neonates. We recommend that an international consensus be reached on which parameters should be used and the thresholds defining severity of disease.

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.

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.

Outcomes of Extremely Preterm Infants With Birth Weight Less Than 400 g

IMPORTANCE

Birth weight (BW) is an important predictor of mortality and morbidity. At extremely early gestational ages (GAs), BW may influence decisions regarding initiation of resuscitation.

OBJECTIVE

To characterize outcomes of liveborn infants with a BW less than 400 g.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective multicenter cohort study analyzed extremely preterm infants born between January 2008 and December 2016 within the National Institute of Child Health and Human Development Neonatal Research Network. Infants with a BW less than 400 g and a GA of 22 to 26 weeks were included. Active treatment was defined as the provision of any potentially lifesaving intervention after birth. Survival was analyzed for the entire cohort; neurodevelopmental impairment (NDI) was examined for those born between January 2008 and December 2015 (birth years with outcomes available for analysis). Neurodevelopmental impairment at 18 to 26 months' corrected age (CA) was defined as a Bayley Scales of Infant and Toddler Development, Third Edition, cognitive composite score less than 85, a motor composite score less than 85, moderate or severe cerebral palsy, gross motor function classification system score of 2 or greater, bilateral blindness, and/or hearing impairment. Data were analyzed from September 2017 to October 2018.

EXPOSURES

Birth weight less than 400 g.

MAIN OUTCOMES AND MEASURES

The primary outcome was survival to discharge among infants who received active treatment. Analysis of follow-up data was limited to infants born from 2008 to 2015 to ensure children had reached assessment age. Within this cohort, neurodevelopmental outcomes were assessed for infants who survived to 18 to 26 months' CA and returned for a comprehensive visit.

RESULTS

Of the 205 included infants, 121 (59.0%) were female, 133 (64.9%) were singletons, and 178 (86.8%) were small for gestational age. Almost half (101 of 205 [49.3%]) received active treatment at birth. A total of 26 of 205 infants (12.7%; 95% CI, 8.5-18.9) overall survived to discharge, and 26 of 101 actively treated infants (25.7%; 95% CI, 17.6-35.4) survived to discharge. Within the subset of infants with a BW less than 400 g and a GA of 22 to 23 weeks, 6 of 36 actively treated infants (17%; 95% CI, 6-33) survived to discharge. Among infants born between 2008 and 2015, 23 of 90 actively treated infants (26%; 95% CI, 17-36) survived to discharge. Two infants died after discharge, and 2 were lost to follow-up. Thus, 19 of 90 actively treated infants (21%; 95% CI, 13-31) were evaluated at 18 to 26 months' CA. Moderate or severe NDI occurred in 14 of 19 infants (74%).

CONCLUSIONS AND RELEVANCE

Infants born with a BW less than 400 g are at high risk of mortality and significant morbidity. Although 21% of infants survived to 18 to 26 months' CA with active treatment, NDI was common among survivors.

Comprehensive Evaluation of Right Heart Performance and Pulmonary Hemodynamics in Neonatal Pulmonary Hypertension : Evaluation of cardiopulmonary performance in neonatal pulmonary hypertension

PURPOSE OF REVIEW

Pulmonary hypertension is characterized by an elevation of pulmonary artery pressures and prolonged exposure of the right ventricle to high afterload that collectively contribute to morbidity and mortality in both the term and preterm infants. This review summarizes the pathogenesis, etiologies, and hemodynamic profiles of the conditions that result in pulmonary hypertension in neonates. We explore the application of echocardiographic techniques for the assessment of right ventricular performance and pulmonary hemodynamics that enhance and guide the diagnosis and management strategies in neonates.

RECENT FINDINGS

Clinical assessments based on the determinants of mean pulmonary artery pressures (pulmonary vascular resistance, pulmonary blood flow, and pulmonary capillary wedge pressure) provide a physiologic approach in determining the acute and chronic etiologies of pulmonary hypertension in neonates. In addition, advances in neonatal echocardiography now afford the capability to obtain quantitative information that often precedes the qualitative information acquired by conventional methods and also provide sensitive markers of right ventricle performance for prognostic information based on the determinants of mean pulmonary artery pressures. Neonatal pulmonary hypertension represents a physiologic spectrum that accounts for the variance in clinical presentation and response to therapies. Physiology-based approaches to etiological identification, coupled with the emerging echocardiographic methods for the assessment of pulmonary hypertension in neonates will likely help to identify cardiovascular compromise earlier, guide therapeutic intervention, monitor therapeutic effectiveness, and improve overall outcome.

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

OBJECTIVES

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

DESIGN

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

RESULTS

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

CONCLUSION

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

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

OBJECTIVE

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

STUDY DESIGN

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

RESULTS

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

CONCLUSIONS

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

Discrepancy between invasive and non-invasive blood pressure readings in extremely preterm infants in the first four weeks of life

Background

The agreement between invasive and non-invasive blood pressure (BP) readings in the first days of life of preterm infants is contentiously debated.

Objective

To compare mean, systolic and diastolic invasive (IBP) and non-invasive BP (NBP) readings obtained during routine care in the first four weeks of life of extremely preterm infants.

Methods

We extracted pairs of IBP and NBP readings obtained from preterm infants born below 28 weeks of gestation from the local database. After exclusion of erroneous measurements, we investigated the repeated measures correlation and analyzed the agreement (bias) and precision adjusted for multiple measurements per individual.

Results

Among 335 pairs of IBP and NBP readings obtained from 128 patients, we found correlation coefficients >0.65 for mean, systolic and diastolic BP values. The bias for mean BP readings was -0.4 mmHg (SD 6.1), for systolic BP readings 6.2 mmHg (SD 8.1), and for diastolic BP readings -4.3 mmHg (SD 6.5). Overestimation of systolic IBP and underestimation of diastolic IBP by the non-invasive measurement were found both in the group with gestational age from 23 to 25.9 weeks and in the group with gestational age from 26 to 27.9 weeks. Systolic NBP readings tended to exceed invasive readings in the range <50 mmHg (bias 9.9 mmHg) whereas diastolic NBP readings were lower than invasive values particularly in the range >30 mmHg (bias -5.5 mmHg).

Conclusion

The disagreement between invasive and non-invasive BP readings in infants extends to the first four weeks of life. Biases differ for mean, systolic and diastolic BP values. Our observation implies that they may depend on the range of the blood pressure. Awareness of these biases and preemptive concomitant use of IBP and NPB readings may contribute to reducing over- or under-treatment.