Advances in Neonatal Pulmonary Hypertension

Bilateral renal agenesis: fetal intervention and outcomes

Bilateral renal agenesis (BRA) is a fetal anomaly which leads to anhydramnios and resultant pulmonary hypoplasia. Historically, this anomaly was universally fatal early in the neonatal period due to the severity of the associated lung disease. Over the last 30 years, innovations in fetal therapies-specifically, serial amnioinfusions-have led to instances of infant pulmonary survival and initiation of postnatal dialysis, raising the possibility that early neonatal death may not be inevitable. Amnioinfusions are not without risk, and maternal complications can include prelabor rupture of membranes, preterm labor, infection, and bleeding. The data detailing neonatal outcomes are still limited and actively being collected. Two case series and one non-randomized clinical trial have supplied most of the known outcome data for infants with BRA after prenatal amnioinfusion. Although there are survivors reported in the literature, mortality remains high, with many deaths in infancy due to dialysis-associated sepsis. In addition, previously unknown morbidities have been documented in these infants, including neurologic injury. These challenges, in addition to the mechanical difficulties of providing dialysis to extremely small infants, can result in significant burdens for patients and their caregivers and moral distress for the health care team. The present review aims to explain the pathophysiology of BRA, detail the historical context and rationale for serial amnioinfusions to treat the pulmonary insufficiency associated with BRA, describe the available data regarding outcomes of infants born following prenatal amnioinfusions, discuss ethical issues surrounding this fetal intervention, and describe critical aspects of prenatal counseling for patients considering the intervention.

Update on Management and Outcomes of Congenital Diaphragmatic Hernia

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

Clinical Characteristics and Outcomes of SARS-CoV-2 Infection in Neonates with Persistent Pulmonary Hypertension of the Newborn (PPHN): A Systematic Review

PPHN is a common cause of neonatal respiratory failure and is still a serious condition that is associated with high mortality.

OBJECTIVES

To analyze the clinical characteristics and outcomes of SARS-CoV-2 infection in neonates with PPHN to identify neonatal cases at risk to develop severe illness.

METHODS

For this systematic review, we adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and searched Medline, Embase, CINAHL, and PubMed for studies on the development of COVID-19 in neonates with PPHN, published from 1 December 2019 to 29 February 2024, with an English language restriction.

RESULTS

Of the 2406 papers that were identified, 21 articles were included in the systematic review. Studies involving thirty-six neonates with PPHN and infected with SARS-CoV-2 were analyzed (twenty-nine survived, six died, and one is still hospitalized). The main causes of PPHN in neonates who had COVID-19 were neonatal respiratory distress syndrome (NRDS) (41.7%), meconium-stained amniotic fluid (MSAF) (16.7%), preterm premature rupture of membranes (PPROM) (11.1%), hypoxic ischemic encephalopathy (HIE) (5.5%), pneumonia (5.5%), and idiopathic (2.8%). Most of those neonates were male (33.3%), belonged to Indian ethnicity (50%), and were delivered via caesarean section (44.4%). COVID-19 in cases with PPHN commonly occurred in neonates born with a pregnancy range from 32 to <37 weeks (moderate to late preterm) (36.1%). The maternal severity of COVID-19 was reported to be severe in three cases only (8.3%); however, SARS-CoV-2 infection in neonates with PPHN was either severe (44.4%) or critical (22.2%). Most of these neonates experienced acute respiratory distress syndrome (ARDS) (58.3%). Early and late multisystem inflammatory syndrome in neonates (MIS-N) were reported in 50% and 11.1%, respectively. A high proportion of neonates were admitted to the intensive care unit (ICU) (58.3%) or needed mechanical ventilation (MV) (47.2%). Neonates with concurrent PPHN and SARS-CoV-2 infection who died had worse severity of COVID-19 [i.e., severity of COVID-19 was critical in 10% (neonates with PPHN who survived group) vs. 83.3% (neonates with PPHN who died group); p = 0.026]. Neonates with PPHN and COVID-19 had a higher relative risk of death if they received more antibiotics (RR 4.14, 95% CI 0.64-6.88) and if their COVID-19 was defined as critical (RR 2.84, 95% CI 0.86-9.39). Male neonates with PPHN and COVID-19 (RR 2.60, 95% CI 0.30-1.17) and those requiring prolonged invasive positive pressure ventilation (RR 2.22, 95% CI 0.64-7.73) also showed an increased relative risk for death.

CONCLUSIONS

COVID-19 in neonates with PPHN is challenging and may be associated with increased mortality, severity, ICU admission, ARDS, MIS-N, and MV usage. The results should be interpreted with caution owing to the small number of studies and substantial heterogeneity and indicate a need for future research in this area. Due to its benefits, testing for SARS-CoV-2 should be encouraged for newborns with symptoms consistent with COVID-19, especially in neonates with a history of SARS-CoV-2 exposure. Effective protection measures should be implemented during delivery and post-delivery care as necessary.

Delivery Room Management of Infants with Surgical Conditions

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

International treatment outcomes of neonates on extracorporeal membrane oxygenation (ECMO) with persistent pulmonary hypertension of the newborn (PPHN): a systematic review

BACKGROUND

PPHN is a common cause of neonatal respiratory failure and is still a serious condition and associated with high mortality.

OBJECTIVES

To compare the demographic variables, clinical characteristics, and treatment outcomes in neonates with PHHN who underwent ECMO and survived compared to neonates with PHHN who underwent ECMO and died.

METHODS

We adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline and searched ProQuest, Medline, Embase, PubMed, CINAHL, Wiley online library, Scopus and Nature for studies on the development of PPHN in neonates who underwent ECMO, published from January 1, 2010 to May 31, 2023, with English language restriction.

RESULTS

Of the 5689 papers that were identified, 134 articles were included in the systematic review. Studies involving 1814 neonates with PPHN who were placed on ECMO were analyzed (1218 survived and 594 died). Neonates in the PPHN group who died had lower proportion of normal spontaneous vaginal delivery (6.4% vs 1.8%; p value > 0.05) and lower Apgar scores at 1 min and 5 min [i.e., low Apgar score: 1.5% vs 0.5%, moderately abnormal Apgar score: 10.3% vs 1.2% and reassuring Apgar score: 4% vs 2.3%; p value = 0.039] compared to those who survived. Neonates who had PPHN and died had higher proportion of medical comorbidities such as omphalocele (0.7% vs 4.7%), systemic hypotension (1% vs 2.5%), infection with Herpes simplex virus (0.4% vs 2.2%) or Bordetella pertussis (0.7% vs 2%); p = 0.042. Neonates with PPHN in the death group were more likely to present due to congenital diaphragmatic hernia (25.5% vs 47.3%), neonatal respiratory distress syndrome (4.2% vs 13.5%), meconium aspiration syndrome (8% vs 12.1%), pneumonia (1.6% vs 8.4%), sepsis (1.5% vs 8.2%) and alveolar capillary dysplasia with misalignment of pulmonary veins (0.1% vs 4.4%); p = 0.019. Neonates with PPHN who died needed a longer median time of mechanical ventilation (15 days, IQR 10 to 27 vs. 10 days, IQR 7 to 28; p = 0.024) and ECMO use (9.2 days, IQR 3.9 to 13.5 vs. 6 days, IQR 3 to 12.5; p = 0.033), and a shorter median duration of hospital stay (23 days, IQR 12.5 to 46 vs. 58.5 days, IQR 28.2 to 60.7; p = 0.000) compared to the neonates with PPHN who survived. ECMO-related complications such as chylothorax (1% vs 2.7%), intracranial bleeding (1.2% vs 1.7%) and catheter-related infections (0% vs 0.3%) were more frequent in the group of neonates with PPHN who died (p = 0.031).

CONCLUSION

ECMO in the neonates with PPHN who failed supportive cardiorespiratory care and conventional therapies has been successfully utilized with a neonatal survival rate of 67.1%. Mortality in neonates with PPHN who underwent ECMO was highest in cases born via the caesarean delivery mode or neonates who had lower Apgar scores at birth. Fatality rate in neonates with PPHN who underwent ECMO was the highest in patients with higher rate of specific medical comorbidities (omphalocele, systemic hypotension and infection with Herpes simplex virus or Bordetella pertussis) or cases who had PPHN due to higher rate of specific etiologies (congenital diaphragmatic hernia, neonatal respiratory distress syndrome and meconium aspiration syndrome). Neonates with PPHN who died may need a longer time of mechanical ventilation and ECMO use and a shorter duration of hospital stay; and may experience higher frequency of ECMO-related complications (chylothorax, intracranial bleeding and catheter-related infections) in comparison with the neonates with PPHN who survived.

Congenital diaphragmatic hernia-associated pulmonary hypertension

Congenital diaphragmatic hernia (CDH) is characterized by a developmental insult which compromises cardiopulmonary embryology and results in a diaphragmatic defect, allowing abdominal organs to herniate into the hemithorax. Among the significant pathophysiologic components of this condition is pulmonary hypertension (PH), alongside pulmonary hypoplasia and cardiac dysfunction. Fetal pulmonary vascular development coincides with lung development, with the pulmonary vasculature evolving alongside lung maturation. However, in CDH, this embryologic development is impaired which, in conjunction with external compression, stifle pulmonary vascular maturation, leading to reduced lung density, increased muscularization of the pulmonary vasculature, abnormal vascular responsiveness, and altered molecular signaling, all contributing to pulmonary arterial hypertension. Understanding CDH-associated PH (CDH-PH) is crucial for development of novel approaches and effective management due to its significant impact on morbidity and mortality. Antenatal and postnatal diagnostic methods aid in CDH risk stratification and, specifically, pulmonary hypertension, including fetal imaging and gas exchange assessments. Management strategies include lung protective ventilation, fluid optimization, pharmacotherapies including pulmonary vasodilators and hemodynamic support, and extracorporeal life support (ECLS) for refractory cases. Longitudinal re-evaluation is an important consideration due to the complexity and dynamic nature of CDH cardiopulmonary physiology. Emerging therapies such as fetal endoscopic tracheal occlusion and pharmacological interventions targeting key CDH pathophysiological mechanisms show promise but require further investigation. The complexity of CDH-PH underscores the importance of a multidisciplinary approach for optimal patient care and improved outcomes.

Hyperoxemia among Pediatric Intensive Care Unit Patients Receiving Oxygen Therapy

Supratherapeutic oxygen levels consistently cause oxygen toxicity in the lungs and other organs. The prevalence and severity of hyperoxemia among pediatric intensive care unit (PICU) patients remain unknown. This was the first study to examine the prevalence and duration of hyperoxemia in PICU patients receiving oxygen therapy. This is a retrospective chart review. This was performed in a setting of 36-bed PICU in a quaternary-care children's hospital. All the patients were children aged <18 years, admitted to the PICU for ≥24 hours, receiving oxygen therapy for ≥12 hours who had at least one arterial blood gas during this time. There was no intervention. Of 5,251 patients admitted to the PICU, 614 were included in the study. On average, these patients received oxygen therapy for 91% of their time in the PICU and remained hyperoxemic, as measured by pulse oximetry, for 65% of their time on oxygen therapy. Patients on oxygen therapy remained hyperoxemic for a median of 38 hours per patient and only 1.1% of patients did not experience any hyperoxemia. Most of the time (87.5%) patients received oxygen therapy through a fraction of inspired oxygen (FiO 2 )-adjustable device. Mean FiO 2 on noninvasive support was 0.56 and on invasive support was 0.37. Mean partial pressure of oxygen (PaO 2 ) on oxygen therapy was 108.7 torr and 3,037 (42.1%) of PaO 2 measurements were >100 torr. Despite relatively low FiO 2 , PICU patients receiving oxygen therapy are commonly exposed to prolonged hyperoxemia, which may contribute to ongoing organ injury.

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.

Pulmonary Hypertension in Developmental Lung Diseases

Diverse genetic developmental lung diseases can present in the neonatal period with hypoxemic respiratory failure, often associated with with pulmonary hypertension. Intractable hypoxemia and lack of sustained response to medical management should increase the suspicion of a developmental lung disorder. Genetic diagnosis and lung biopsy are helpful in establishing the diagnosis. Early diagnosis can result in optimizing management and redirecting care if needed. This article reviews normal lung development, various developmental lung disorders that can result from genetic abnormalities at each stage of lung development, their clinical presentation, management, prognosis, and differential diagnoses.

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

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

Management Practices During Perinatal Respiratory Transition of Very Premature Infants

The present review considers some controversial management practices during extremely premature perinatal transition. We focus on perinatal prevention and treatment of respiratory distress syndrome (RDS) in immature infants. New concerns regarding antenatal corticosteroid management have been raised. Many fetuses are only exposed to potential adverse effects of the drug. Hence, the formulation and the dosage may need to be modified. Another challenge is to increase the fraction of the high-risk fetuses that benefit from the drug and to minimize the harmful effects of the drug. On the other hand, boosting anti-inflammatory and anti-microbial properties of surfactant requires further attention. Techniques of prophylactic surfactant administration to extremely immature infants at birth may be further refined. Also, new findings suggest that prophylactic treatment of patent ductus arteriosus (PDA) of a high-risk population rather than later selective closure of PDA may be preferred. The TREOCAPA trial (Prophylactic treatment of the ductus arteriosus in preterm infants by acetaminophen) evaluates, whether early intravenous paracetamol decreases the serious cardiorespiratory consequences following extremely premature birth. Lastly, is inhaled nitric oxide (iNO) used in excess? According to current evidence, iNO treatment of uncomplicated RDS is not indicated. Considerably less than 10% of all very premature infants are affected by early persistence of pulmonary hypertension (PPHN). According to observational studies, effective ventilation combined with early iNO treatment are effective in management of this previously fatal disease. PPHN is associated with prolonged rupture of fetal membranes and birth asphyxia. The lipopolysaccharide (LPS)-induced immunotolerance and hypoxia-reperfusion-induced oxidant stress may inactivate NO-synthetases in pulmonary arterioles and terminal airways. Prospective trials on iNO in the management of PPHN are indicated. Other pulmonary vasodilators may be considered as comparison drugs or adjunctive drugs. The multidisciplinary challenge is to understand the regulation of pregnancy duration and the factors participating the onset of extremely premature preterm deliveries and respiratory adaptation. Basic research aims to identify deficiencies in maternal and fetal tissues that predispose to very preterm births and deteriorate the respiratory adaptation of immature infants. Better understanding on causes and prevention of extremely preterm births would eventually provide effective antenatal and neonatal management practices required for the intact survival.

Risk Factors and Outcomes of Acute Kidney Injury in Neonates with Persistent Pulmonary Hypertension of the Newborn

Objective

To identify the incidence of and risk factors for acute kidney injury (AKI) in neonates with persistent pulmonary hypertension of the newborn (PPHN) and to evaluate its association with neonatal outcomes.

Method

A total of 78 newborns with confirmed PPHN admitted to the neonatal intensive care unit of a university hospital between 2016 and 2020 were retrospectively analyzed. AKI was defined according to the modified neonatal Kidney Disease: Improving Global Outcomes criteria.

Results

Of 78 PPHN infants, AKI was found in 29.5% (23/78). Multivariate analysis indicated that male sex (OR 3.43 95% CI 1.03-11.48, p=0.04) and severe PPHN (OR 5.67 95% CI 1.55-20.68, p<0.01) were independently associated with increased risk for AKI. Infants with AKI had significantly higher mortality rate than infants without AKI (43.5% vs. 9.1%, p<0.01). Mortality rates in stage 1, stage 2 and stage 3 AKI were similar (36.4%, 57.1%, and 40%, respectively, p=0.68). Among survivors, AKI infants had significantly longer mechanical ventilation and lenght of stay than infants without AKI.

Conclusion

In infants with PPHN, AKI is a common complication and is associated with increased mortality, and longer mechanical ventilation and lenght of stay. Careful monitoring of kidney function in infants with PPHN, especially in males and those who had severe PPHN can help to improve patient outcomes.

Survival and associated risk factors for mortality among infants with persistent pulmonary hypertension of the newborn in Malaysia

OBJECTIVE

This study aims to determine the immediate outcome of persistent pulmonary hypertension of the newborn (PPHN) and risk factors for mortality in the era of inhaled nitric oxide (iNO).

STUDY DESIGN

This observational cross-sectional study includes 195 confirmed PPHN with a gestational age of ≥34 weeks without congenital heart disease. Multivariable logistic regression was used to identify risk factors for mortality.

RESULTS

The mortality rate was 16.4%, with the highest mortality with pulmonary hypoplasia. Of 195, 65% received iNO; 18% were iNO non-responders with the majority having pulmonary hypoplasia. Independent risk factors for mortality were the presence of reversal of flow at the descending aorta, pulmonary hypoplasia, APGAR scores ≤ 5 at 5 min, and idiopathic PPHN with an adjusted odds ratio of 15.9, 7.5, 6.7, and 6.4, respectively.

CONCLUSIONS

Despite the usage of iNO, mortality due to PPHN remains high and is related to etiology and cardiac function.

Inhaled Nitric Oxide Is Associated with Improved Oxygenation in a Subpopulation of Infants with Congenital Diaphragmatic Hernia and Pulmonary Hypertension

OBJECTIVES

To determine which patients with congenital diaphragmatic hernia (CDH) and pulmonary hypertension (PH) benefit from inhaled nitric oxide (iNO) treatment by comparing characteristics and outcomes of iNO responders to nonresponders.

STUDY DESIGN

We performed a retrospective chart review of infants with CDH treated at our center between 2011 and 2016. In a subset of patients, iNO was initiated for hypoxemia or echocardiographic evidence of extrapulmonary right to left shunting. Initial post-treatment blood gases were reviewed, and patients were classified as responders (increased PaO₂ >20 mm Hg) or nonresponders. Baseline characteristics, echocardiograms and outcomes were compared between groups with Fisher exact tests and Mann-Whitney t tests, as appropriate.

RESULTS

During the study period, 95 of 131 patients with CDH (73%) were treated with iNO. All patients with pretreatment echocardiograms (n = 90) had echocardiographic evidence of PH. Thirty-eight (40%) patients met treatment response criteria. Responders had significant improvements in PaO₂ (51 ± 3 vs 123 ± 7 mm Hg, P < .01), alveolar-arterial gradient (422 ± 30 vs 327 ± 27 mm Hg, P < .01), and PaO₂ to FiO₂ ratio (82 ± 10 vs 199 ± 15 mm Hg, P < .01). Nonresponders were more likely to have left ventricular systolic dysfunction (27% vs 8%, P = .03) on echocardiogram. Responders were less likely to require extracorporeal membrane support (50 vs 24%, P = .02).

CONCLUSIONS

iNO treatment is associated with improved oxygenation and reduced need for ECMO in a subpopulation of patients with CDH with PH and normal left ventricular systolic function.

Extra-Corporeal Membrane Oxygenation for Neonatal Respiratory Support

To review our experience with Extra-Corporeal Membrane Oxygenation (ECMO) for respiratory support in neonates. From 1989 to 2018 2114 patients underwent respiratory ECMO support, with 764 (36%) neonates. Veno-Venous (V-V) cannulation was used in 428 (56%) neonates and Veno-Arterial (V-A) in 336 (44%). Historically V-V ECMO was our preferred modality, but due to lack of suitable cannula in the last 7 years V-A was used in 209/228 (92%) neonates. Mean and inter-quartile range of ECMO duration was 117 hours (inter-quartile range 90 to 164 hours). Overall 724 (95%) neonates survived to ECMO decannulation, with 640 (84%) hospital discharge. Survival varied with underlying diagnosis: meconium aspiration 98% (354/362), persistent pulmonary hypertension 80% (120/151), congenital diaphragmatic hernia 66% (82/124), sepsis 59% (35/59), pneumonia 86% (6/7), other 71% (43/61). Survival was 86% with V-V and 80% with V-A cannulation, better than ELSO Registry with 77% V-V and 63% V-A. Major complications: cerebral infarction/hemorrhage in 4.7% (31.1% survival to discharge), renal replacement therapy in 17.6% (58.1% survival to discharge), new infection in 2.9%, with negative impact on survival (30%). Following a circuit design modification and subsequent reduction in heparin requirement, intracerebral hemorrhage decreased to 9/299 (3.0%) radiologically proven cerebral infarction/hemorrhage. We concluded (1) outcomes from neonatal ECMO in our large case series were excellent, with better survival and lower complication rate than reported in ELSO registry. (2) These results highlight the benefits of ECMO service in high volume units. (3) The similar survival rate seen in neonates with V-A and V-V cannulation differs from the ELSO register; this may reflect the change in cannulation enforced by lack of suitable V-V cannula and all neonates undergoing V-A cannulation.

Neonatal respiratory extracorporeal membrane oxygenation and primary diagnosis: trends between two decades

OBJECTIVE

Examine changing neonatal respiratory extracorporeal membrane oxygenation (ECMO) practice trends and outcomes.

STUDY DESIGN

Retrospective cohort study comparing neonatal respiratory ECMO in the 1990 and 2010 decades (1994-1995 and 2014-2015). Patients ≤ 30 days of life, reported to the Extracorporeal Life Support Organization registry, were included.

RESULTS

Four thousand one hundred and twenty-five patients met inclusion criteria. ECMO cases decreased by 33%. The primary ECMO diagnosis changed significantly over time (p < 0.0001). Survival to discharge decreased (76 vs 67%, p < 0.0001) and ECMO duration increased (131 vs 158 h, p < 0.001). Lung recovery was the most common reason to discontinue ECMO although family request for withdrawal and a diagnosis considered "incompatible with life" was increasingly common in the 2010s.

CONCLUSION

Although the use of ECMO for neonatal respiratory diagnoses has decreased over time, its use has increased for patients with more complex diagnoses and ECMO duration is longer. ECMO continues to be an important supportive therapy, improved understanding of which patients would benefit most is needed.

Accuracy and reliability of qualitative echocardiography assessment of right ventricular size and function in neonates

BACKGROUND

Subjective assessment of right ventricular (RV) function by neonatal echocardiography lacks validation. Incorrect diagnostic assignment in patients with suspected pulmonary hypertension (PH) may lead to unnecessary treatment or missed treatment opportunities.

METHODS

Six evaluators (experts [n = 3], novice [n = 3]) were asked to independently rate RV characteristics (global function, dilation, and septal flattening) based on standardized echocardiography images. We randomly selected 60 infants, ≥35 weeks gestation at birth, of whom 30 were clinically unwell with acute pulmonary hypertension (aPH) and 30 were healthy controls. aPH was defined by echocardiography presence of right-left shunting across transitional shunts or elevated right ventricular systolic pressure as estimated by the magnitude of the regurgitant jet across the tricuspid valve with impaired oxygenation. Inter-rater comparative evaluation within groups and between groups was performed using Kappa statistics.

RESULTS

Global agreement between evaluators for subjective assessment of RV function (0.3 [0.03], P < 0.001), size (0.14 [0.02], P < 0.001), and septal flattening (0.2 [0.02], P < 0.001) was uniformly poor. Agreement in RV function assessment was marginally better for both expert (0.32 [0.08], P < 0.001 vs 0.13 [0.081], and P < 0.001) and novice (0.4 [0.08], P < 0.001 vs 0.06 [0.07], and P < 0.001) evaluators. Overall, the diagnosis of aPH vs control was misclassified in 18% of cases.

CONCLUSION

This study demonstrated significant variability in qualitative assessment of RV size and function by trained evaluators, regardless of level of expertise attained. The reliability of objective measures of RV hemodynamics requires prospective evaluation.

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.

Current understanding and perioperative management of pediatric pulmonary hypertension

Pediatric pulmonary hypertension is a complex disease with multiple, diverse etiologies affecting the premature neonate to the young adult. Pediatric pulmonary arterial hypertension, whether idiopathic or associated with congenital heart disease, is the most commonly discussed form of pediatric pulmonary hypertension, as it is progressive and lethal. However, neonatal forms of pulmonary hypertension are vastly more frequent, and while most cases are transient, the risk of morbidity and mortality in this group deserves recognition. Pulmonary hypertension due to left heart disease is another subset increasingly recognized as an important cause of pediatric pulmonary hypertension. One aspect of pediatric pulmonary hypertension is very clear: anesthetizing the child with pulmonary hypertension is associated with a significantly heightened risk of morbidity and mortality. It is therefore imperative that anesthesiologists who care for children with pulmonary hypertension have a firm understanding of the pathophysiology of the various forms of pediatric pulmonary hypertension, the impact of anesthesia and sedation in the setting of pulmonary hypertension, and anesthesiologists' role as perioperative experts from preoperative planning to postoperative disposition. This review summarizes the current understanding of pediatric pulmonary hypertension physiology, preoperative risk stratification, anesthetic risk, and intraoperative considerations relevant to the underlying pathophysiology of various forms of pediatric pulmonary hypertension.

Effects of vasopressin during a pulmonary hypertensive crisis induced by acute hypoxia in a rat model of pulmonary hypertension

BACKGROUND

A pulmonary hypertensive crisis (PHC) can be a life-threatening condition. We established a PHC model by exposing rats with monocrotaline (MCT)-induced pulmonary hypertension to acute hypoxia, and investigated the effects of vasopressin, phenylephrine, and norepinephrine on the PHC.

METHODS

Four weeks after MCT 60 mg kg^-1 administration i.v., right ventricular systolic pressure (RVSP), systolic BP (SBP), mean BP (MBP), cardiac index (CI), and pulmonary vascular resistance index (PVRI) were measured. PHC defined as an RVSP exceeding or equal to SBP was induced by changing the fraction of inspiratory oxygen to 0.1. Rats were subsequently treated by vasopressin, phenylephrine, or norepinephrine, followed by assessment of systemic haemodynamics, isometric tension of femoral and pulmonary arteries, cardiac function, blood gas composition, and survival.

RESULTS

PHC was associated with increased RV dilatation and paradoxical septal motion. Vasopressin increased MBP [mean (standard error)] from 52.6 (3.8) to 125.0 (8.9) mm Hg and CI from 25.4 (2.3) to 40.6 (1.8) ml min^-1 100 g^-1 while decreasing PVRI. Vasopressin also improved RV dilatation, oxygenation, and survival in PHC. In contrast, phenylephrine increased MBP from 54.8 (2.3) to 96.8 (3.2) mm Hg without improving cardiac pump function. Norepinephrine did not alter MBP. Vasopressin contracted femoral but not pulmonary arteries, whereas phenylephrine contracted both arterial beds. Hence, improvements with vasopressin in PHC might be associated with decreased PVRI and selective systemic vasoconstriction.

CONCLUSIONS

In this rat model of a PHC, vasopressin, but not phenylephrine or norepinephrine, resulted in better haemodynamic and vascular recovery.

Life-Threatening Extreme Methemoglobinemia during Standard Dose Nitric Oxide Therapy

We report the first case of life-threatening extreme neonatal-acquired methemoglobinemia that occurred during inhaled nitric oxide (iNO) at the standard 20 ppm dose in a neonate with early onset sepsis and suprasystemic pulmonary hypertension. Life-threatening methemoglobinemia has been efficaciously treated with methylene blue and ascorbic acid, while stopping iNO and starting iloprost and sildenafil. The patient was subjected to various tests (including gene sequencing and hemoglobin electrophoresis) and did not have any known genetic cause or predisposition for methemoglobinemia. Neuroimaging and the 2-year clinical follow-up were completely normal.

Lung Ultrasound to Assess the Etiology of Persistent Pulmonary Hypertension of the Newborn (LUPPHYN Study): A Pilot Study

INTRODUCTION

Persistent pulmonary hypertension of the newborn (PPHN) is a neonatal syndrome associated with significant morbidity and mortality that is caused by the failure of postnatal drop in pulmonary vascular resistance. In extreme cases, patients may require extracorporeal membrane oxygenation therapy (ECMO). The aim of this study was to explore lung ultrasound (LUS) patterns in newborns with PPHN requiring ECMO.

PATIENTS AND METHODS

From January 2014 to January 2018, LUS was performed on patients with PPHN admitted for ECMO treatment. PPHN diagnosis was based on clinical and echocardiographic findings. LUS was performed before patients underwent ECMO cannulation. An underlying diagnosis was made taking into account the patient's complete medical history, excluding LUS information. A blinded physician, unaware of the patient's clinical condition, analyzed the stored ultrasound images. Results were then compared with chest x-ray (CXR) diagnoses.

RESULTS

Seventeen patients were recruited; 12 were male (70.6%). The median gestational age was 38.7 weeks, with 13 term newborns (76.5%). Twelve were cannulated for VA ECMO, with a median ECMO run of 111.2 h. Six patients (35%) survived. Patients with alveolar capillary dysplasia with misaligned pulmonary veins, fetal ductus arteriosus constriction, or sepsis had normal LUS patterns (A-lines with lung sliding). LUS showed a better sensitivity (88.9%) and specificity (85%) than CXR (55.6 and 77.5%, respectively) in identifying patients with nonparenchymal lung disease.

CONCLUSIONS

LUS can provide essential information to help diagnose the underlying cause of PPHN in an earlier and more effective way than CXR. LUS is suitable for routine utilization in the intensive care unit.

Accuracy of Pulse Oximetry Screening for Critical Congenital Heart Defects after Home Birth and Early Postnatal Discharge

OBJECTIVE

To assess the accuracy of pulse oximetry screening for critical congenital heart defects (CCHDs) in a setting with home births and early discharge after hospital deliveries, by using an adapted protocol fitting the work patterns of community midwives.

STUDY DESIGN

Pre- and postductal oxygen saturations (SpO₂) were measured ≥1 hour after birth and on day 2 or 3. Screenings were positive if the SpO₂ measurement was <90% or if 2 independent measures of pre- and postductal SpO₂ were <95% and/or the pre-/postductal difference was >3%. Positive screenings were referred for pediatric assessment. Primary outcomes were sensitivity, specificity, and false-positive rate of pulse oximetry screening for CCHD. Secondary outcome was detection of noncardiac illnesses.

RESULTS

The prenatal detection rate of CCHDs was 73%. After we excluded these cases and symptomatic CCHDs presenting immediately after birth, 23 959 newborns were screened. Pulse oximetry screening sensitivity in the remaining cohort was 50.0% (95% CI 23.7-76.3) and specificity was 99.1% (95% CI 99.0-99.2). Pulse oximetry screening was false positive for CCHDs in 221 infants, of whom 61% (134) had noncardiac illnesses, including infections (31) and respiratory pathology (88). Pulse oximetry screening did not detect left-heart obstructive CCHDs. Including cases with prenatally detected CCHDs increased the sensitivity to 70.2% (95% CI 56.0-81.4).

CONCLUSION

Pulse oximetry screening adapted for perinatal care in home births and early postdelivery hospital discharge assisted the diagnosis of CCHDs before signs of cardiovascular collapse. High prenatal detection led to a moderate sensitivity of pulse oximetry screening. The screening also detected noncardiac illnesses in 0.6% of all infants, including infections and respiratory morbidity, which led to early recognition and referral for treatment.

Continuous intravenous sildenafil as an early treatment in neonates with congenital diaphragmatic hernia

BACKGROUND

Pulmonary hypertension (PH) is an important contributor of morbidity and mortality in infants with congenital diaphragmatic hernia (CDH). Treatment options are limited, but sildenafil might improve oxygenation and PH in neonates with CDH.

OBJECTIVE

Aim of this study is to assess effects of intravenous sildenafil on oxygenation and PH in neonates with CDH.

METHODS

A retrospective chart review was performed in all neonates with CDH born in our institution between September 2012 and December 2014. Indication for sildenafil was an OI > 15, PH > 2/3 systemic pressure, or a difference in pre- and postductal oxygen saturation (≥8%). A sildenafil bolus was administered followed by a maintenance infusion of 1.6 mg/kg/d. Primary outcome was improved oxygenation after starting sildenafil. Patients were compared according to improvement in oxygenation (responder vs non-responder).

RESULTS

A total of 26 of 44 neonates were treated with intravenous sildenafil and in all sildenafil were initiated within the first 24 h of life (median age 3.1 h). Improved oxygenation was observed in 11 infants (42.3%). Among the 15 non-responders (57.6%) ECMO was started in 13 and two infants died without ECMO. Vasopressor support increased significantly during the first hours after commencing sildenafil in responders and non-responders. Echocardiographic indices demonstrated an effect on pulmonary arterial pressure within the first 24 h after starting sildenafil.

CONCLUSIONS

Treatment of neonates with intravenous sildenafil during the first day of life was associated with acute improvement in oxygenation in more than 40% of patients. However, a significant increase in vasopressor support was observed.

The Research Cycle: Improving Care and Outcomes for Newborn Infants

Ensuring that policies and practice in perinatal care are informed by evidence from high-quality research is fundamental to improving outcomes for newborn infants and their families. Effective interventions in the perinatal period can have a life-long impact disproportionate to their costs. Many of the major advances in care that have transformed outcomes for preterm and sick newborn infants have been informed by empirical and applied health research. Conversely, there are examples of life-long adverse consequences for infants and families that are a legacy of practices based on poor-quality evidence. The challenge in the 21st century is to maintain the trajectory of improvements in care and outcomes. This will most likely be achieved via marginal gains from new or improved care practices underpinned by a range of research approaches, from preclinical and laboratory-based empirical studies that uncover pathogenic pathways or therapeutic mechanisms, to large-scale, applied research such as multicentre, randomised controlled trials. This will involve the coordination and collaboration of research efforts globally. Strategies to develop and prioritise research questions need to involve parents and families. Given the context in which much perinatal research is conducted, particularly in emergency situations around the time of birth, robust and transparent ethics and governance frameworks are essential to maintain the trust and engagement of communities. An ethical imperative exists to ensure that research output is disseminated effectively, and that effective and cost-effective interventions are implemented and integrated within a cycle that audits and benchmarks good practice and outcomes, and informs research evidence-based continuous quality improvement. This is the first in a series of articles on research methodology in neonatal medicine to be published in Neonatology, in response to a request from trainee researchers. We introduce the series by describing the research cycle, in particular how it is applied in neonatal medicine. Subsequent articles will cover translational research, clinical trials, diagnostic tests, global challenges, and the ethical issues relating to neonatal/perinatal research.

Effects of FHL1 and P21 on hypoxia-induced pulmonary vascular remodeling in neonatal rats

Numerous studies have demonstrated that altered expression levels of four and a half LIM domains 1 (FHL1) and P21 are necessary for hypoxia-induced pulmonary vascular remodeling in both adult rats and human patients with idiopathic pulmonary arterial hypertension. However, whether FHL1 and P21 are present in the pulmonary artery and whether these proteins affect pulmonary vascular remodeling in hypoxia-induced pulmonary hypertension (HPH) in neonatal rats remain unknown. The present study investigated the effects of altered FHL1 and P21 expression on pulmonary vascular remodeling in neonatal rats with HPH. A total of 32 newborn Sprague-Dawley rats were exposed to hypoxia or room air for 7 or 14 days (n=8/subgroup). Parameters including the percentage of medial wall thickness (WT%), the percentage of medial wall area (WA%), right ventricular (RV) mean pressure, RV hypertrophy index (RVHI) and RV systolic pressure (RVSP) were measured to evaluate the development of HPH. Additionally, the expressions of FHL1 and P21 in the pulmonary artery smooth muscle cells (PASMCs) were measured by reverse transcription-quantitative polymerase chain reaction, western blot analysis and immunohistochemical staining. WA%, WT%, RV mean pressure, RVHI and RVSP were significantly increased in the HPH model group when compared with the control group (P<0.01). The protein expression levels of FHL1 were significantly increased in the HPH group (P<0.05), while the mRNA and protein expression levels of P21 were significantly reduced (P<0.05). Pearson correlation analysis indicated that the protein expressions of FHL1 and P21 were correlated with WA% and WT% (all P<0.001), and that the protein expression of P21 was negatively correlated with that of FHL1 (P<0.01). The results indicated that the expressions of FHL1 and P21 were altered in the PASMCs of newborn rats with HPH. Furthermore, FHL1 and P21 may serve important roles in pulmonary vascular remodeling.

The Fetus Can Teach Us: Oxygen and the Pulmonary Vasculature

Neonates suffering from pulmonary hypertension of the newborn (PPHN) continue to represent an important proportion of patients requiring intensive neonatal care, and have an increased risk of morbidity and mortality. The human fetus has evolved to maintain a high pulmonary vascular resistance (PVR) in utero to allow the majority of the fetal circulation to bypass the lungs, which do not participate in gas exchange, towards the low resistance placenta. At birth, oxygen plays a major role in decreasing PVR to enhance pulmonary blood flow and establish the lungs as the organ of gas exchange. The failure of PVR to fall following birth results in PPHN, and oxygen remains the mainstay therapeutic intervention in the management of PPHN. Knowledge gaps on what constitutes the optimal oxygenation target leads to a wide variation in practices, and often leads to excessive oxygen use. Owing to the risk of oxygen toxicity, avoiding hyperoxemia is as important as avoiding hypoxemia in the management of PPHN. Current evidence supports maintaining arterial oxygen tension in the range of 50–80 mm Hg, and oxygen saturation between 90–97% in term infants with hypoxemic respiratory failure. Clinical studies evaluating the optimal oxygenation in the treatment of PPHN will be enthusiastically awaited.

Treatment of Persistent Pulmonary Hypertension of the Newborn: Use of Pulmonary Vasodilators in Term Neonates

Persistent pulmonary hypertension of the newborn (PPHN) represents a challenging condition associated with significant morbidity. A successful transition from intrauterine to extrauterine life is contingent on adequate pulmonary vasodilation. Several pathophysiologies contribute to the failure of this cascade and may result in life-threatening hypoxia and acidosis in the newborn. Management includes optimal respiratory support, adequate sedation and analgesia, and support of vascular tone and cardiac function. Pulmonary vasodilation has the potential to overcome the cycle of hypoxia and acidosis, improving outcome in these infants. Oxygen and inhaled nitric oxide represent the foundation of therapy. Tertiary pulmonary vasodilators represent a greater challenge, selecting between therapies that include prostanoids, sildenafil, and milrinone. Variable levels of evidence exist for each agent. Thorough review of available data informing efficacy and adverse effects contributes to the development of an informed approach to neonates with refractory PPHN.

[Clinicopathological analysis of pulmonary vascular disease in 38 neonates died of respiratory failure]

We reviewed the data of 38 neonates who died of respiratory failure. Paraffin sections of the autopsy lung samples were examined with HE staining or immunolabeling for CD34, CD68 and CK to observe the development of the pulmonary vessels and detect potential pulmonary vascular diseases (PVDs). Five cases were identified to have PVDs, including pulmonary hypertensive vascular remodeling in 3 cases and alveolar capillary dysplasia in 2 cases. The result indicated that PVD was one of the important reasons for respiratory failure in these neonates.