Persistent pulmonary hypertension of the newborn in the era before nitric oxide: practice variation and outcomes

Meconium Aspiration Syndrome, Hypoxic-Ischemic Encephalopathy and Therapeutic Hypothermia-A Recipe for Severe Pulmonary Hypertension?

Hypoxic-ischemic encephalopathy (HIE) is the leading cause of mortality among term newborns globally. Infants born through meconium-stained amniotic fluid are at risk of developing meconium aspiration syndrome (MAS) and HIE. Simultaneous occurrence of MAS and HIE is a perilous combination for newborns due to the risk of persistent pulmonary hypertension of the newborn (PPHN). Moreover, therapeutic hypothermia (TH), which is the current standard of care for the management of HIE, may increase pulmonary vascular resistance (PVR) and worsen PPHN. Infants with MAS and HIE require close cardiorespiratory and hemodynamic monitoring for PPHN. Therapeutic strategies, including oxygen supplementation, ventilation, use of surfactant, inhaled nitric oxide and other pulmonary vasodilators, and systemic vasopressors, play a critical role in the management of PPHN in MAS, HIE, and TH. While TH reduces death or disability in infants with HIE, infants with MAS and HIE undergoing TH need close hemodynamic monitoring for PPHN.

Defining the Typical Course of Persistent Pulmonary Hypertension of the Newborn: When to Think Beyond Reversible Causes

OBJECTIVES

To describe the typical clinical course of reversible persistent pulmonary hypertension of the newborn (PPHN) from perinatal etiologies and compare that with the clinical course of PPHN due to underlying fetal developmental etiologies.

STUDY DESIGN

This was a single-center, retrospective cohort study of liveborn newborns either born or transferred to our facility for higher level of care between 2015 and 2020 with gestational age ≥35 weeks and a clinical diagnosis of PPHN in the electronic health record. Newborns with complex congenital heart disease and congenital diaphragmatic hernia were excluded. Using all data available at time of collection, newborns were stratified into 2 groups by PPHN etiology - perinatal and fetal developmental causes. Primary outcomes were age at initiation, discontinuation, and total duration of extracorporeal life support, mechanical ventilation, supplemental oxygen, inhaled nitric oxide, inotropic support, and prostaglandin E1. Our secondary outcome was age at echocardiographic resolution of pulmonary hypertension. Groups were compared by t-test. Time-to-event Kaplan Meier curves described and compared (log-rank test) discontinuation of each therapy.

RESULTS

Sixty-four (72%) newborns had perinatal etiologies whereas 24 (28%) had fetal developmental etiologies. The resolution of perinatal PPHN was more rapid compared with fetal developmental PPHN. By 10 days of age, more neonates were off inotropes (98% vs 29%, P < .01), decannulated from extracorporeal life support (100% vs 0%, P < .01), extubated (75% vs 37%, P < .01), and had echocardiographic resolution of PH (35% vs 7%, P = .02).

CONCLUSIONS

An atypical PPHN course, characterized by persistent targeted therapies in the second week of life, warrants further work-up for fetal developmental causes.

Study on the comparison between Bosentan and Macitentan in the treatment of persistent pulmonary hypertension of the newborns, simultaneously on sildenafil: A randomized double-blinded non-inferiority parallel clinical trial

BACKGROUND

Persistent Pulmonary Hypertension of the newborn (PPHN) is characterized by sustained elevated Pulmonary Artery Pressure (PAP). Drug resistance and the adverse effects of current therapeutic agents warrant investigation of other targeted therapies. Bosentan has shown benefits in affected neonates. However, trials reported the association with unwanted effects. Thus, in this study, we assess another agent in the same family, Macitentan. However, its efficacy in the treatment of PPHN is not yet reported. Hence, this study evaluated the effect of Macitentan compared to Bosentan in terms of efficacy and safety in the treatment of PPHN.

METHODS

This randomized, double-blinded non-inferiority clinical trial was conducted in Shahid Akbar Abadi hospital, Tehran, Iran. Sixty clinically stable neonates with signs suggestive of PPHN were randomly allocated into two groups (n = 30 in each group) and they received either Bosentan 1 mg/kg/dose BD (twice daily) or Macitentan 1 mg/kg/dose BD simultaneously with sildenafil. The echocardiographic and laboratory indices of efficacy and safety were compared between groups. SPAP (systolic pulmonary artery pressure) was used to assess the non-inferiority of the Macitentan compared to the Bosentan in their respective doses used in the study.

RESULTS

Participants' mean (SD) age was 3.53 (1.21) days, and 55% were female. No mortality case occurred. SPAP was reduced in both Bosentan and Macitenan groups with the mean difference in SPAP of 9 (95% CI: 7.34-10.65) in Bosentan and SPAP mean difference of 14 (95% CI: 12.12-15.86) in Macitentan group. Categorical comparison of primary outcome improvement showed that Macitentan was superior to Bosentan with a 10% non-inferiority margin. Similar results were obtained in other echocardiographic indices. Also, no significant alterations were observed in laboratory safety parameters.

CONCLUSION

Macitentan 1 mg/kg/dose BD (twice daily) is non-inferior to Bosentan 1 mg/kg/dose BD in improving echo outcomes of PPHN and it was even more effective in improving some of these. Also, it is non-inferior to Bosentan in terms of safety. TRIAL REGISTRY NUMBER: (IRCT20160120026115N9).

Vasopressin in newborns with refractory acute pulmonary hypertension

BACKGROUND

Acute pulmonary hypertension (aPH) in newborns can be life threatening and challenging to manage. In newborns with refractory aPH, there is currently limited therapeutic agents.

METHODS

Retrospective single-center cohort study in newborns less than one month old who were treated with vasopressin for a minimum of one hour in the context of refractory aPH in the neonatal and pediatric intensive care units of a tertiary university center between 2016 and 2022. The objective was to evaluate the efficacy and safety of vasopressin in newborns as an adjuvant treatment for refractory aPH.

RESULTS

Twenty-five patients met inclusion criteria. In patients who received vasopressin, oxygenation index improved from 28.4 to 14.4 (p = 0.004) after twelve hours of continuous infusion. Oxygen requirements (FiO2) decreased from 0.91 to 0.50 (p = 0.004) and mean arterial pressure increased from 41 to 51 mmHg (p = 0.001). In our cohort, 68% of patients presented an episode of hyponatremia (serum sodium <130 mmol/L).

CONCLUSIONS

The use of vasopressin may be associated with improvement in oxygenation and hemodynamic status of neonatal patients with aPH refractory to initial therapy. Further prospective studies are needed to establish the safety profile of vasopressin in newborns, particularly in preterm infants.

IMPACT

Vasopressin may be an effective cardiotropic agent to improve oxygenation and hemodynamic status in newborns with acute pulmonary hypertension. Careful monitoring of serum sodium levels are warranted in newborns who are receiving vasopressin infusion. This provides additional evidence for the consideration of vasopressin in newborns with acute pulmonary hypertension refractory to inhaled nitric oxide.

Occurrence of hyperoxia during iNO treatment for persistent pulmonary hypertension of the newborn: a cohort study

High concentrations of oxygen are often needed to optimize oxygenation in infants with persistent pulmonary hypertension (PPHN), but this can also increase the risk of hyperoxemia. We determined the occurrence of hyperoxemia in infants treated for PPHN. Medical records of infants ≥ 34 + 0 weeks gestational age (GA) who received inhaled nitric oxide (iNO) were retrospectively reviewed for oxygenation parameters during iNO therapy. Oxygen was manually titrated to target arterial oxygen tension (PaO2) 10-13 kPa and peripheral oxygen saturation (SpO2) 92-98%. The main study outcomes were the incidence and duration of hyperoxemia and hypoxemia and the fraction of inspired oxygen (FiO2). A total of 181 infants were included. The median FiO2 was 0.43 (IQR 0.34-0.56) and the maximum FiO2 was 1.0 in 156/181 (86%) infants, resulting in at least one PaO2 > 13 kPa in 149/181 (82%) infants, of which 46/149 (31%) infants had minimal one PaO2 > 30 kPa. SpO2 was > 98% in 179/181 (99%) infants for 17.7% (8.2-35.6%) of the iNO time. PaO2 < 10 kPa occurred in 160/181 (88%) infants, of which 81/160 (51%) infants had minimal one PaO2 < 6.7 kPa. SpO2 was < 92% in 169/181 (93%) infants for 1.6% (0.5-4.3%) of the iNO time.    Conclusion: While treatment of PPHN is focused on preventing and reversing hypoxemia, hyperoxemia occurs inadvertently in most patients. What is Known: • High concentrations of oxygen are often needed to prevent hypoxemia-induced deterioration of PPHN, but this can also increase the risk of hyperoxemia. • Infants with persistent pulmonary hypertension may be particularly vulnerable to the toxic effects of oxygen, and hyperoxemia could further induce pulmonary vasoconstriction, potentially worsening the condition. What is New: • Hyperoxemia occurs in the majority of infants with PPHN during treatment with iNO. • Infants with PPHN spent a considerably longer period with saturations above the target range compared to saturations below the target range.

Enhancing Neonatal Care: The Vital Role of Pulse Oximetry in the Early Screening of Critical Congenital Heart Diseases and Respiratory Diseases in Rural Areas

Background Pulse oximetry screening (POS) is acknowledged globally as a noninvasive method to detect critical congenital heart diseases (CCHDs) and respiratory illnesses. However, its value for early diagnosis and treatment remains unrecognized in many hospitals with limited resources around the world. This study aimed to evaluate POS's application in CCHDs, persistent pulmonary hypertension (PPHN), and respiratory distress syndrome (RDS) for early diagnosis and its influence on clinical procedures in rural areas. Methods This prospective observational study included all eligible newborn infants in the regional neonatal unit of a community healthcare center. Their peripheral oxygen saturation was assessed at <24 hours and >24 hours after birth, in the right upper limb and either lower limb. An oxygen saturation of <95% or >3% difference between pre-ductal and post-ductal circulations was considered abnormal. All neonates with abnormal oxygen saturations at >24 hours after birth were subjected to another POS test within two hours of the last test. If the oxygen saturation was still abnormal, it was considered a positive POS test. The POS results were classified as oxygen saturation abnormal (<90%), abnormal (90-94%), and normal (≥95%). All neonates with a positive POS test were referred for echocardiography. Results Overall, 440 infants had documented POS results. A total of 65 (14.77%) infants had a positive POS test result, out of which 39 (8.86%) cases were diagnosed on further evaluation. Four neonates had CCHD (positive predictive value (PPV) = 6.15%), 26 had RDS (PPV = 40%), and nine had PPHN (PPV = 13.85%). Without any further delay, the doctor directed them all to a more advanced facility. Conclusion Our research showed that, in large-scale clinical settings, the addition of pulse oximetry to routine cardiac auscultation could be a reliable and feasible method to screen newborns for CCHD, PPHN, and RDS early on. Our research underscores the importance of implementing routine POS to detect CCHD, RDS, and PPHN in clinical practice.

Etiology, Diagnosis and Management of Persistent Pulmonary Hypertension of the Newborn in Resource-limited Settings

Persistent Pulmonary Hypertension of the Newborn (PPHN) is more common in Low and middle income countries (LMICs) due to high incidence of sepsis, perinatal asphyxia and meconium aspiration syndrome. Presence of hypoxic respiratory faillure and greater than 5% difference in preductal and post ductal saturation increases clinical sucipision for PPHN. The availability of Inhaled nitric oxide and extracorporaeal membrane oxygenation is limited but pulmonary vasodilators such as sildenafil are readily available in most LMICs.

Randomized Controlled Trials of Pulmonary Vasodilator Therapy Adjunctive to Inhaled Nitric Oxide for Persistent Pulmonary Hypertension of the Newborn: A Systematic Review

Inhaled nitric oxide (iNO) is a pulmonary vasodilator considered standard of care to treat persistent pulmonary hypertension of the newborn. However, not all infants respond to iNO. The authors performed a systematic review to examine methodology, outcomes, and challenges of randomized controlled trials testing pulmonary vasodilator medications adjunctive to iNO. The 5 trials identified showed heterogeneity in eligibility criteria and outcomes assessed. No trial achieved recruitment goals, limiting conclusions regarding efficacy, safety, and pharmacology. Trial design consensus and alternative methodologic strategies such as deferred consent, real-world controls, nonrandomized database assessments, and Bayesian statistical approaches are needed.

Persistent Pulmonary Hypertension of Newborns Secondary to Labile Hypoxemia Associated With Cyanosis: A Case Series

Persistent pulmonary hypertension of the newborn (PPHN) is a condition that can be fatal, marked by increased pulmonary vascular resistance that causes blood to shunt from the right to the left. Six infants that present with PPHN due to labile hypoxemia and related cyanosis are examined in this case series. Clinical manifestations, such as premature deliveries, maternal problems, and different reactions to early therapies, are revealed by perinatal and postnatal histories. The newborns' respiratory distress prompted the use of oxygen supplementation and continuous positive airway pressure (CPAP), but intubation was required due to continued hypoxemia. The series aims to establish a way for further study in this crucial area while offering insightful contributions to the clinical subtleties of PPHN and illustrating the importance of specific therapeutic approaches.

Short term effect of intravenous treprostinil in term and preterm infants with pulmonary hypertension

BACKGROUND

Pulmonary hypertension (PH) is a life-threatening condition in newborns. We aimed to assess the clinical and echocardiographic responses of term and preterm infants to treprostinil.

METHODS

This retrospective study included newborns diagnosed with PH and treated with treprostinil as additional therapy after inhaled nitric oxide administration in the neonatal intensive care unit of a tertiary center. Term and preterm infants were compared in terms of echocardiographic findings and clinical findings 4 weeks after treprostinil treatment.

RESULTS

During the study period, 11 term and 18 preterm infants were diagnosed with PH and received treprostinil. There were no differences in the echocardiographic findings of interventricular septal deviation, direction of shunt, and ratio of estimated pulmonary artery pressure over systolic blood pressure. Congenital diaphragmatic hernia was the most common condition occurring upon PH diagnosis among term infants, while severe bronchopulmonary dysplasia was the most common in preterm infants. Improvements in echocardiographic findings were more pronounced in term infants than in preterm infants (100% vs. 55.6%, P = 0.012). The inhaled nitric oxide dose was gradually tapered for term infants and was lower than that for preterm infants at 1, 2, and 3 weeks after treprostinil.

CONCLUSION

Intravenous treprostinil could be an adjuvant therapy option for term and preterm infants with PH, especially for those who cannot receive oral medication. The efficacy and safety of treprostinil in this population with PH should be investigated further.

Mechanistic analysis of the photolytic decomposition of solid-state S-nitroso-N-acetylpenicillamine

S-Nitroso-N-acetylpenicillamine (SNAP) is among the most common nitric oxide (NO)-donor molecules and its solid-state photolytic decomposition has potential for inhaled nitric oxide (iNO) therapy. The photochemical NO release kinetics and mechanism were investigated by exposing solid-state SNAP to a narrow-band LED as a function of nominal wavelength and intensity of incident light. The photolytic efficiency, decomposition products, and the photolytic pathways of the SNAP were examined. The maximum light penetration depth through the solid layer of SNAP was determined by an optical microscope and found to be within 100-200 μm, depending on the wavelength of light. The photolysis of solid-state SNAP to generate NO along with the stable thiyl (RS·) radical was confirmed using Electron Spin Resonance (ESR) spectroscopy. The fate of the RS· radical in the solid phase was studied both in the presence and absence of O2 using NMR, IR, ESR, and UPLC-MS. The changes in the morphology of SNAP due to its photolysis were examined using PXRD and SEM. The stable thiyl radical formed from the photolysis of solid SNAP was found to be reactive with another adjacent thiyl radical to form a disulfide (RSSR) or with oxygen to form various sulfonyl and sulfonyl peroxyl radicals {RS(O)xO·, x = 0 to 7}. However, the thiyl radical did not recombine with NO to reform the SNAP. From the PXRD data, it was found that the SNAP loses its crystallinity by generating the NO after photolysis. The initial release of NO during photolysis was increased with increased intensity of light, whereas the maximum light penetration depth was unaffected by light intensity. The knowledge gained about the photochemical reactions of SNAP may provide important insight in designing portable photoinduced NO-releasing devices for iNO therapy.

Growth and developmental outcomes of infants with hypoxic ischemic encephalopathy

Despite advances in obstetric care, hypoxic ischemic encephalopathy (HIE) remains a significant disease burden. We determined the national trends of HIE prevalence, therapeutic hypothermia (TH) use, mortality, and outcomes from 2012 to 2019. This study included term infants diagnosed with HIE between 2012 and 2019 from the National Health Insurance Service database. The prevalence of HIE was 2.4 per 1000 births without significant change during the period. TH was performed in approximately 6.7% of infants with HIE, and the annual variation ranged from 2.4 to 12.5%. The mortality among all term infants with HIE was 4.6%. The mortality rate among infants with HIE and TH significantly declined from 40 to 16.9% during the eight years. Infants with TH had higher mortality, increased use of inhaled nitric oxide, and more invasive ventilator use, indicating greater disease severity in the TH group. Infants with TH also showed significantly poorer outcomes, including delayed development, cerebral palsy, sensorineural hearing loss, and seizure, compared to infants without TH (p < 0.0001). With the increasing application of TH, mortality and developmental outcomes among infants with HIE have been improving in the past eight years in Korea. Further efforts to improve outcomes should be needed.

Meconium aspiration syndrome: a comprehensive review

Meconium aspiration syndrome (MAS) is a complex respiratory disease that continues to be associated with significant morbidities and mortality. The pathophysiological mechanisms of MAS include airway obstruction, local and systemic inflammation, surfactant inactivation and persistent pulmonary hypertension of the newborn (PPHN). Supplemental oxygen and non-invasive respiratory support are the main therapies for many patients. The management of the patients requiring invasive mechanical ventilation could be challenging because of the combination of atelectasis and air trapping. While studies have explored various ventilatory modalities, evidence to date does not clearly support any singular modality as superior. Patient's pathophysiology, symptom severity, and clinician/unit expertise should guide the respiratory management. Early identification and concomitant management of PPHN is critically important as it contributes significantly to mortality and morbidities.

Evidence-Based Guidelines for Acute Stabilization and Management of Neonates with Persistent Pulmonary Hypertension of the Newborn

Persistent pulmonary hypertension of the newborn, or PPHN, represents a challenging condition associated with high morbidity and mortality. Management is complicated by complex pathophysiology and limited neonatal specific evidence-based literature, leading to a lack of universal contemporary clinical guidelines for the care of these patients. To address this need and to provide consistent high-quality clinical care for this challenging population in our neonatal intensive care unit, we sought to develop a comprehensive clinical guideline for the acute stabilization and management of neonates with PPHN. Utilizing cross-disciplinary expertise and incorporating an extensive literature search to guide best practice, we present an approachable, pragmatic, and clinically relevant guide for the bedside management of acute PPHN. KEY POINTS: · PPHN is associated with several unique diagnoses; the associated pathophysiology is different for each unique diagnosis.. · PPHN is a challenging, dynamic, and labile process for which optimal care requires frequent reassessment.. · Key management goals are adequate tissue oxygen delivery, avoiding harm..

Intact cord resuscitation in newborns with congenital diaphragmatic hernia: insights from a lamb model

Introduction

Congenital diaphragmatic hernia (CDH) is a rare condition characterized by pulmonary hypoplasia, vascular dystrophy, and pulmonary hypertension at birth. Validation of the lamb model as an accurate representation of human CDH is essential to translating research findings into clinical practice and understanding disease mechanisms. This article emphasizes the importance of validating the lamb model to study CDH pathogenesis and develop innovative therapeutics.

Material and methods

At 78 days of gestation, the fetal lamb's left forelimb was exposed through a midline laparotomy and hysterotomy, and a supra diaphragmatic thoracotomy was performed to allow the digestive organs to ascend into the thoracic cavity. At 138 ± 3 days of gestation, lambs were delivered via a cesarean section; then, with umbilical cord intact during 1 hour, the lambs were mechanically ventilated with gentle ventilation in a pressure-controlled mode for 2 h.

Results

CDH lambs exhibited a lower left lung-to-body weight ratio of 5.3 (2.03), p < 0.05, and right lung-to-body weight ratio of 8.2 (3.1), p < 0.05. They reached lower Vt/kg (tidal volume per kg) during the course of the resuscitation period with 1.2 (0.7) ml/kg at 10 min and 3 (1.65) ml/kg at 60 min (p < 0.05). Compliance of the respiratory system was lower in CDH lambs with 0.5 (0.3) ml/cmH2O at 60 min (p < 0.05) and 0.9 (0.26) ml/cmH2O at 120 min (p < 0.05). Differences between pre- and postductal SpO2 were higher with 15.1% (21.4%) at 20 min and 6.7% (14.5%) at 80 min (p < 0.05). CDH lambs had lower differences between inspired and expired oxygen fractions with 4.55% (6.84%) at 20 min and 6.72% (8.57%) at 60 min (p < 0.05). CDH lamb had lower left ventricle [2.73 (0.5) g/kg, p < 0.05] and lower right ventricle [0.69 (0.8), p < 0.05] to left ventricle ratio.

Discussion

CDH lambs had significantly lower tidal volume than control lambs due to lower compliance of the respiratory system and higher airway resistance. These respiratory changes are characteristic of CDH infants and are associated with higher mortality rates. CDH lambs also exhibited pulmonary hypertension, pulmonary hypoplasia, and left ventricle hypoplasia, consistent with observations in human newborns. To conclude, our lamb model successfully provides a reliable representation of CDH and can be used to study its pathophysiology and potential interventions.

Perinatal Depression: A Review and an Update

Perinatal depression is a common psychiatric condition that has negative effects on pregnancy and infant outcomes. Screening for the condition is relatively easy and should be done routinely in all medical care of the pregnant and postpartum woman and her infant. The risk-benefit analysis favors the use of antidepressant medications during pregnancy and lactation compared with the risk of untreated maternal depression. Other, nonpharmacological treatments will be discussed as well as new treatments, including a new class of medications that act on the inhibitory GABAergic neurotransmitter system.

Inhaled iloprost is an effective alternative therapy for persistent pulmonary hypertension in newborns

Persistent pulmonary hypertension of the newborn (PPHN) is one of the diseases of the neonate with severe potential morbidity and mortality. Inhaled iloprost, a stable prostacyclin analog, has been suggested as an alternative treatment for inhaled nitric oxide (iNO). However, more data on neonates' dosing, setting, and effectiveness still needs to be solved. This study suggests using inhaled iloprost as rescue therapy for PPHN based on our experience. This was a retrospective study. The data from medical records of six newborns diagnosed with PPHN and had received inhaled iloprost from December 2019 to April 2022 were collected. Demographic and clinical features, dosing regimen, changes in oxygenation index, echocardiographic findings, and mortality were evaluated. The inhalation dose was 2-4 mcg/dose, and 3-48 inhalations per day were applied over 2-7 days. Inhaled iloprost was effective in all patients. No side effects were attributable to inhaled iloprost, and no mortality was recorded. Our experience suggests that inhaled iloprost can be used as a first-line therapy in newborn infants with PPHN when iNO is unavailable. However, there are large fluctuations in the oxygenation index due to the setting.

Management of neonatal pulmonary hypertension-a survey of neonatal intensive care units in India

BACKGROUND

Persistent pulmonary hypertension of the newborn (PPHN) is a common neonatal condition associated with significant morbidity and mortality. First-line diagnostic and treatment options such as echocardiography and inhaled nitric oxide (iNO) are not routinely available in resource limited settings and alternative treatment modalities need to be utilized. This study was conducted to assess current diagnostic and management strategies used for PPHN in Indian neonatal intensive care units (NICUs).

METHODS

A questionnaire in multiple choice question format was sent to practising neonatologists in India via an online survey tool between July to August 2021. Information pertaining to demographic data, diagnostic criteria and management strategies of PPHN was requested. The responses were collated and information processed.

RESULTS

There were 118 respondent NICUs (response rate 74%). The majority of neonatal units (65%) admitted an average of 1-3 patients of PPHN per month. Targeted neonatal echocardiography (TnECHO) was practised in 80% of the units. Most common management strategies being followed were pulmonary vasodilators (88.1%), inotropes (85.6%), conventional ventilation (68.6%) and high frequency ventilation (59.3%). The most preferred pulmonary vasodilator was sildenafil (79%) and inotropic agent was milrinone (32%). Only 25% of respondents reported use of iNO. None of the participating units used extracorporeal membrane oxygenation.

CONCLUSION

We found wide variability in management practices of PPHN across Indian NICUs. Non-selective pulmonary vasodilators are more widely used than iNO. There is an urgent need for structured TnECHO training programs and evidence based national guidelines for standardized management of PPHN as per availability of resources in India. Additional research on low cost alternative therapies to iNO in Indian settings might be helpful.

Pharmacotherapy for Pulmonary Hypertension in Infants with Bronchopulmonary Dysplasia: Past, Present, and Future

Approximately 8-42% of premature infants with chronic lung disease of prematurity, bronchopulmonary dysplasia (BPD), develop pulmonary hypertension (PH). Infants with BPD-PH carry alarmingly high mortality rates of up to 47%. Effective PH-targeted pharmacotherapies are desperately needed for these infants. Although many PH-targeted pharmacotherapies are commonly used to treat BPD-PH, all current use is off-label. Moreover, all current recommendations for the use of any PH-targeted therapy in infants with BPD-PH are based on expert opinion and consensus statements. Randomized Control Trials (RCTs) are needed to determine the efficacy of PH-targeted treatments in premature infants with or at risk of BPD-PH. Prior to performing efficacy RCTs, studies need to be conducted to obtain pharmacokinetic, pharmacodynamic, and safety data for any pharmacotherapy used in this understudied and fragile patient population. This review will discuss current and needed treatment strategies, identify knowledge deficits, and delineate both challenges to be overcome and approaches to be taken to develop effective PH-targeted pharmacotherapies that will improve outcomes for premature infants with or at risk of developing BPD-PH.

Analgesia, Sedation, and Neuromuscular Blockade in Infants with Congenital Diaphragmatic Hernia

OBJECTIVE

The aim of this study was to describe the use, duration, and intercenter variation of analgesia and sedation in infants with congenital diaphragmatic hernia (CDH).

STUDY DESIGN

This is a retrospective analysis of analgesia, sedation, and neuromuscular blockade use in neonates with CDH. Patient data from 2010 to 2016 were abstracted from the Children's Hospitals Neonatal Database and linked to the Pediatric Health Information System. Patients were excluded if they also had non-CDH conditions likely to affect the use of the study medications.

RESULTS

A total of 1,063 patients were identified, 81% survived, and 30% were treated with extracorporeal membrane oxygenation (ECMO). Opioid (99.8%), sedative (93.4%), and neuromuscular blockade (87.9%) use was common. Frequency of use was higher and duration was longer among CDH patients treated with ECMO. Unadjusted duration of use varied 5.6-fold for benzodiazepines (median: 14 days) and 7.4-fold for opioids (median: 16 days). Risk-adjusted duration of use varied among centers, and prolonged use of both opioids and benzodiazepines ≥5 days was associated with increased mortality (p < 0.001) and longer length of stay (p < 0.001). Use of sedation or neuromuscular blockade prior to or after surgery was each associated with increased mortality (p ≤ 0.01).

CONCLUSION

Opioids, sedatives, and neuromuscular blockade were used commonly in infants with CDH with variable duration across centers. Prolonged combined use ≥5 days is associated with mortality.

KEY POINTS

· Use of analgesia and sedation varies across children's hospital NICUs.. · Prolonged opioid and benzodiazepine use is associated with increased mortality.. · Postsurgery sedation and neuromuscular blockade are associated with mortality..

The use of milrinone in neonates with persistent pulmonary hypertension of the newborn - a randomised controlled trial pilot study (MINT 1)

OBJECTIVE

To assess the impact of milrinone administration on time spent on nitric oxide (iNO) in infants with acute pulmonary hypertension (aPH). We hypothesized that intravenous milrinone used in conjunction with iNO would reduce the time on iNO therapy and the time spent on invasive ventilation in infants ≥34 weeks gestation with a diagnosis of aPH. We aimed to assess the practicality of instituting the protocol and contributing to a sample size calculation for a definitive multicentre study.

STUDY DESIGN

This was a multicentre, randomized, double-blind, two arm pilot study, with a balanced (1:1) allocation. Infants with a gestation ≥34 weeks and a birth weight ≥2000 grams aPH, an oxygenation index of ≥10, and commenced on iNO were eligible. Participants on iNO were assigned to either a milrinone infusion (intervention) or a normal saline infusion (placebo) for up to 35 h. The primary outcome was time on iNO and feasibility of conducting the protocol.

RESULTS

The trial was terminated early after 4 years of enrollment due to poor recruitment. Four infants were allocated to the intervention arm and 5 to the placebo arm. The groups were well matched for baseline variables. No differences were seen in any of the primary or secondary outcomes.

CONCLUSION

Conducting an interventional trial in the setting of acute pulmonary hypertension in infants is not feasible using our current approach. Future studies in this area require alternative trial design to improve recruitment as this topic remains understudied in the neonatal field.

TRIAL REGISTRATION

www.isrctn.com ; ISRCTN:12949496; EudraCT Number:2014-002988-16.

An electrochemical nitric oxide generator for in-home inhalation therapy in pulmonary artery hypertension

BACKGROUND

Inhaled NO is a selective pulmonary vasodilator proven to be therapeutic for patients with pulmonary artery hypertension (PAH). The most common NO delivery system in clinical practice is cylinder-based, but unfortunately limited by its high costs, complicated delivery, and the requirement of an extensive supply chain, leaving vast unmet medical needs globally.

METHODS

To address the need for rapid, affordable, and safe production of nitric oxide (NO) for in-home inhalation therapy in patients with PAH. We developed a novel portable device to derive NO from a nitrite complex solution with a copper(II)-ligand catalyst, and further examined its effectiveness in a porcine model of PAH. This model was established by using female Bama miniature pig and induced by monocrotaline (MCT) administration.

RESULTS

This generator could rapidly and safely produce therapeutic NO at concentrations ranging from 0 to 100 parts per million (ppm) with the least disproportionated nitrogen dioxide (NO2) and byproducts. It could effectively alleviate pulmonary arterial pressure (PAP) and pulmonary vascular resistance (PVR) in piglets with PAH, without causing major physiologic disruptions.

CONCLUSIONS

Our electrochemical NO generator is able to produce the desired NO doses for pulmonary vasodilation in a safe and sustainable way, with low costs, which paves the way for its subsequent clinical trials in the patient with PAH and other common cardiopulmonary conditions with a high disease burden around the world.

Outcome prediction in newborn infants: Past, present, and future

The perinatal and neonatal periods are the periods of considerable organ development and maturation. Perinatal and neonatal illnesses can result in mortality and morbidities that burden families and the healthcare system. Outcome prediction is essential for informing perinatal and intensive care management, prognosis, and post-discharge interventions. The Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network (NRN) research databases include hospital and neurodevelopment follow-up outcomes of infants with various underlying diseases and conditions receiving intensive care, providing a unique opportunity to assess outcome risk prediction. The NRN has developed outcome risk prediction tools for use in infants with various diseases and conditions that allow data-driven, transparent discussions to inform family-focused communications and clinical management. This review presents the published neonatal outcome risk prediction research from the NRN, their present clinical utility, and possible future directions for advanced individualized risk prediction.

Morbidity and mortality in neonates with Down Syndrome based on gestational age

BACKGROUND

Greater than 50% of neonates with Down Syndrome (DS) have perinatal complications that require admission to the neonatal intensive care unit (NICU) at birth. Previous studies have shown increased morbidity and mortality rates in neonates without DS delivered prior to 39 weeks of completed gestation.

OBJECTIVE

To determine if an association exists between gestational age at delivery and adverse outcomes in neonates with DS.

STUDY DESIGN

Neonates with DS admitted to a large, tertiary care center NICU from 2010 to 2020 were evaluated. Gestational age (GA) was stratified into 4 groups: <34 (preterm), 34-36 (late-preterm), 37-38 (early-term) and ≥39 (term + post-term) completed weeks. Fisher's exact tests were used to evaluate morbidity and mortality rates between groups.

RESULT

Of the 314 neonates with DS, 10% (N = 31) were <34 weeks, 22% (N = 68) 34-36 weeks, 40% (N = 127) 37-38 weeks, and 28% (N = 88) ≥39 completed weeks at birth. Baseline characteristics were similar between groups. GA at birth <34 weeks was associated with a higher in-hospital mortality rate when compared to those born 37-38 (19% vs. 0%, P < 0.001) and ≥39 (19% vs. 3%, P = 0.01). Neonates with DS born <34 weeks had a higher likelihood of oxygen requirement at time of discharge compared to 34-36, 37-38, and ≥39 groups (P = 0.01; P < 0.001; P < 0.001 respectively). Neonates with DS < 34 weeks were more likely to develop necrotizing enterocolitis (P = 0.02) and require nitric oxide (P = 0.014) compared to neonates with DS ≥ 39. We observed no differences in the need for surgical interventions between groups aside from the rate of gastrostomy/jejunostomy tube placement between 34-36 weeks and 37-38 weeks GA.

CONCLUSION

Neonates with DS born preterm (<34 weeks) represent a highly vulnerable subgroup. Multidisciplinary strategies are needed to address their higher rates of morbidity and mortality.

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.

Long term outcome of babies with pulmonary hypertension

Neonatal pulmonary hypertension (PH) is associated with many severe congenital abnormalities (congenital diaphragmatic hernia) or acquired cardiorespiratory diseases such as pneumonia, meconium aspiration and bronchopulmonary dysplasia (BPD). If no cause is found it may be labelled idiopathic persistent pulmonary hypertension of the newborn. Although PH may result in life threatening hypoxia and circulatory failure, in the majority of cases, it resolves in the neonatal period following treatment of the underlying cause. However, in some cases, neonatal PH progresses into infancy and childhood where symptoms include failure to thrive and eventually right heart failure or death if left untreated. This chronic condition is termed pulmonary vascular hypertensive disease (PHVD). Although classification and diagnostic criteria have only recently been proposed for pediatric PHVD, little is known about the pathophysiology of chronic neonatal PH, or why pulmonary vascular resistance may remain elevated well beyond infancy. This review explores the many factors involved in chronic PH and what implications this may have on long term outcome when the disease progresses beyond the neonatal period.

Persistent pulmonary hypertension of the newborn: Historical perspectives

For many decades, persistent pulmonary hypertension of the newborn (PPHN) remained a baffling disorder, often confused with cyanotic congenital heart disease, with a very high mortality. Originally described as a condition characterized by clear lung fields and profound hypoxemia, modern diagnostic techniques and novel therapeutics have improved the outcomes of affected newborns. This paper will review the historical aspects of PPHN and enable the reader to see how far we have come but also how far we have to go in conquering this unique disorder.

Cinaciguat (BAY-582667) Modifies Cardiopulmonary and Systemic Circulation in Chronically Hypoxic and Pulmonary Hypertensive Neonatal Lambs in the Alto Andino

Neonatal pulmonary hypertension (NPHT) is produced by sustained pulmonary vasoconstriction and increased vascular remodeling. Soluble guanylyl cyclase (sGC) participates in signaling pathways that induce vascular vasodilation and reduce vascular remodeling. However, when sGC is oxidized and/or loses its heme group, it does not respond to nitric oxide (NO), losing its vasodilating effects. sGC protein expression and function is reduced in hypertensive neonatal lambs. Currently, NPHT is treated with NO inhalation therapy; however, new treatments are needed for improved outcomes. We used Cinaciguat (BAY-582667), which activates oxidized and/or without heme group sGC in pulmonary hypertensive lambs studied at 3,600 m. Our study included 6 Cinaciguat-treated (35 ug kg−1 day−1x 7 days) and 6 Control neonates. We measured acute and chronic basal cardiovascular variables in pulmonary and systemic circulation, cardiovascular variables during a superimposed episode of acute hypoxia, remodeling of pulmonary arteries and changes in the right ventricle weight, vasoactive functions in small pulmonary arteries, and expression of NO-sGC-cGMP signaling pathway proteins involved in vasodilation. We observed a decrease in pulmonary arterial pressure and vascular resistance during the acute treatment. In contrast, the pulmonary pressure did not change in the chronic study due to increased cardiac output, resulting in lower pulmonary vascular resistance in the last 2 days of chronic study. The latter may have had a role in decreasing right ventricular hypertrophy, although the direct effect of Cinaciguat on the heart should also be considered. During acute hypoxia, the pulmonary vascular resistance remained low compared to the Control lambs. We observed a higher lung artery density, accompanied by reduced smooth muscle and adventitia layers in the pulmonary arteries. Additionally, vasodilator function was increased, and vasoconstrictor function was decreased, with modifications in the expression of proteins linked to pulmonary vasodilation, consistent with low pulmonary vascular resistance. In summary, Cinaciguat, an activator of sGC, induces cardiopulmonary modifications in chronically hypoxic and pulmonary hypertensive newborn lambs. Therefore, Cinaciguat is a potential therapeutic tool for reducing pulmonary vascular remodeling and/or right ventricular hypertrophy in pulmonary arterial hypertension syndrome.

[Early risk factors for death in neonates with persistent pulmonary hypertension of the newborn treated with inhaled nitric oxide]

OBJECTIVES

To evaluate the early risk factors for death in neonates with persistent pulmonary hypertension of the newborn (PPHN) treated with inhaled nitric oxide (iNO).

METHODS

A retrospective analysis was performed on 105 infants with PPHN (gestational age ≥34 weeks and age <7 days on admission) who received iNO treatment in the Department of Neonatology, Children's Hospital of Nanjing Medical University, from July 2017 to March 2021. Related general information and clinical data were collected. According to the clinical outcome at discharge, the infants were divided into a survival group with 79 infants and a death group with 26 infants. Univariate and multivariate Cox regression analyses were used to evaluate the risk factors for death in infants with PPHN treated with iNO. The receiver operating characteristic (ROC) curve was used to calculate the cut-off values of the factors in predicting the death risk.

RESULTS

A total of 105 infants with PPHN treated with iNO were included, among whom 26 died (26/105, 24.8%). The multivariate Cox regression analysis showed that no early response to iNO (HR=8.500, 95%CI: 3.024-23.887, P<0.001), 1-minute Apgar score ≤3 points (HR=10.094, 95%CI: 2.577-39.534, P=0.001), a low value of minimum PaO2/FiO2 within 12 hours after admission (HR=0.067, 95%CI: 0.009-0.481, P=0.007), and a low value of minimum pH within 12 hours after admission (HR=0.049, 95%CI: 0.004-0.545, P=0.014) were independent risk factors for death. The ROC curve analysis showed that the lowest PaO2/FiO2 value within 12 hours after admission had an area under the ROC curve of 0.783 in predicting death risk, with a sensitivity of 84.6% and a specificity of 73.4% at the cut-off value of 50, and the lowest pH value within 12 hours after admission had an area under the ROC curve of 0.746, with a sensitivity of 76.9% and a specificity of 65.8% at the cut-off value of 7.2.

CONCLUSIONS

Infants with PPHN requiring iNO treatment tend to have a high mortality rate. No early response to iNO, 1-minute Apgar score ≤3 points, the lowest PaO2/FiO2 value <50 within 12 hours after admission, and the lowest pH value <7.2 within 12 hours after admission are the early risk factors for death in such infants. Monitoring and evaluation of the above indicators will help to identify high-risk infants in the early stage.

Predicting the Severity and Outcome of Persistent Pulmonary Hypertension of the Newborn Using New Echocardiography Parameters

OBJECTIVE

To examine echocardiographic (ECHO) parameters correlation with clinical severity indices, Alveolar- arterial gradient (A-a gradient), oxygenation index (OI) and clinical outcomes in newborns with persistent pulmonary hypertension of the newborn (PPHN).

STUDY DESIGN

Retrospective cohort study of 67 subjects, >35 weeks' gestation with the diagnosis of PPHN admitted to the University of Kentucky neonatal intensive care unit (NICU) between September 2014 and December 2016.

RESULTS

High left ventricular end-systolic eccentricity index (EIs) correlates with the overall clinical severity of PPHN as it is associated with higher A-a gradient and OI (p=0.0003 and p<0.0001, respectively). Elevated EIs was also predictive for the use of inhaled nitric oxide (iNO) and extracorporeal membrane oxygenation (ECMO) (p=0.0004 and p<0.0001, respectively). EIs value of >1.38 provides cutoff value as an objective marker for the need for ECMO.

CONCLUSION

EIs can be used to assess clinical severity and outcomes and should be reported routinely. Further studies are warranted to confirm these results.

Use of off-label compounded oral sildenafil in the management of persistent pulmonary hypertension of the newborn: A case report

We report a case of a newborn with persistent pulmonary hypertension (PPHN) due to meconium aspiration syndrome with associated lung collapse. Echocardiogram revealed features of persistent pulmonary hypertension. He was treated with compounded oral sildenafil. Oral sildenafil has proven to be effective and safe in the management of PPHN in neonates with persistent pulmonary hypertension. Therefore, in situations where inhaled nitric oxide is not available it may be used as an alternative therapy in PPHN. Further randomized controlled studies are needed to determine its efficacy and pharmacokinetics.

Risk Factors of Persistent Pulmonary Hypertension in Neonate in A Tertiary Care Referral Center

Background: Persistent pulmonary hypertension of the newborn (PPHN) is a condition in which pulmonary vascular resistance fails to decrease after birth. PPHN leads to hypoxemia due to right-to-left shunting of the blood through the fetal circulation. This study aimed to determine the association between PPHN and prematurity in neonates admitted to the neonatal intensive care unit (NICU).

Materials and methods: This study is a single-center, retrospective, and cross-sectional study. Patients diagnosed with PPHN had been selected by using a non-probability consecutive sampling technique from 2016 to 2020 at King Abdulaziz Medical City in Jeddah, Saudi Arabia. Patients with PPHN who did not admit to NICU were excluded.

Results: Fifty-six patients had met the inclusion and exclusion criteria. Twenty-six neonates were born prematurely before 37 weeks of gestation, and 30 were born at 37 weeks or more. Among the study population, respiratory complications were seen in 30 patients with a rate of 53.6%. The most common complications were respiratory failure, persistent pulmonary hypertension, and cardiopulmonary arrest.

Conclusion: Mortality was documented in 26 patients, with the complicated group having a rate of 73.3% compared to the uncomplicated group 15.4%. The most common complications seen in our patients were respiratory failure, persistent pulmonary hypertension, and cardiopulmonary arrest.

The Action of 2-Aminoethyldiphenyl Borinate on the Pulmonary Arterial Hypertension and Remodeling of High-Altitude Hypoxemic Lambs

Calcium signaling is key for the contraction, differentiation, and proliferation of pulmonary arterial smooth muscle cells. Furthermore, calcium influx through store-operated channels (SOCs) is particularly important in the vasoconstrictor response to hypoxia. Previously, we found a decrease in pulmonary hypertension and remodeling in normoxic newborn lambs partially gestated under chronic hypoxia, when treated with 2-aminoethyldiphenyl borinate (2-APB), a non-specific SOC blocker. However, the effects of 2-APB are unknown in neonates completely gestated, born, and raised under environmental hypoxia. Accordingly, we studied the effects of 2-APB-treatment on the cardiopulmonary variables in lambs under chronic hypobaric hypoxia. Experiments were done in nine newborn lambs gestated, born, and raised in high altitude (3,600 m): five animals were treated with 2-APB [intravenous (i.v.) 10 mg kg^–1] for 10 days, while other four animals received vehicle. During the treatment, cardiopulmonary variables were measured daily, and these were also evaluated during an acute episode of superimposed hypoxia, 1 day after the end of the treatment. Furthermore, pulmonary vascular remodeling was assessed by histological analysis 2 days after the end of the treatment. Basal cardiac output and mean systemic arterial pressure (SAP) and resistance from 2-APB- and vehicle-treated lambs did not differ along with the treatment. Mean pulmonary arterial pressure (mPAP) decreased after the first day of 2-APB treatment and remained lower than the vehicle-treated group until the third day, and during the fifth, sixth, and ninth day of treatment. The net mPAP increase in response to acute hypoxia did not change, but the pressure area under the curve (AUC) during hypoxia was slightly lower in 2-APB-treated lambs than in vehicle-treated lambs. Moreover, the 2-APB treatment decreased the pulmonary arterial wall thickness and the α-actin immunoreactivity and increased the luminal area with no changes in the vascular density. Our findings show that 2-APB treatment partially reduced the contractile hypoxic response and reverted the pulmonary vascular remodeling, but this is not enough to normalize the pulmonary hemodynamics in chronically hypoxic newborn lambs.

Use of vasopressin in persistent pulmonary hypertension of the newborn: A case series

Treatment of neonates with persistent pulmonary hypertension of newborn includes optimization of ventilatory support, use of pulmonary vasodilators, and/or inotropic support. If refractory to this management, some may require extracorporeal membrane oxygenation. We describe a case series of 10 neonates with refractory persistent pulmonary hypertension of newborn treated with vasopressin in a single tertiary center. Mean initiation time of vasopressin was at 30 h of life with a dose ranging from 10 to 85 milliunits/kg/h. Oxygenation index decreased after 12 h of vasopressin exposure (25 to 11) and mean arterial pressure improved after 1 h (45 to 58 mm Hg). Extracorporeal membrane oxygenation was averted in 50% of the cases with transient hyponatremia as the only notable side effect. Although our findings are exploratory and further research is needed to establish safety and efficacy, our experience suggests that vasopressin may have rescue properties in the management of refractory persistent pulmonary hypertension of newborn.

Protocol for a multicenter, double-blind, randomized, placebo-controlled phase III trial of the inhaled β2-adrenergic receptor agonist salbutamol for transient tachypnea of the newborn (the REFSAL trial)

BACKGROUND

Transient tachypnea of the newborn (TTN), which results from inadequate absorption of fetal lung fluid, is the most common cause of neonatal respiratory distress. Stimulation of β-adrenergic receptors enhances alveolar fluid absorption. Therefore, the β2-adrenergic receptor agonist salbutamol has been proposed as a treatment for TTN. This study aims to evaluate the efficacy and safety of salbutamol as supportive pharmacotherapy together with non-invasive nasal continuous positive airway pressure (NIV/nCPAP) for the prevention of persistent pulmonary hypertension of the newborn (PPHN) in infants with TTN.

METHODS AND ANALYSIS

This multicenter, double-blind, phase III trial will include infants with a gestational age between 32 and 42 weeks who are affected by respiratory disorders and treated in eight neonatal intensive care units in Poland. A total of 608 infants within 24 h after birth will be enrolled and randomly assigned (1:1) to receive nebulized salbutamol with NIV or placebo (nebulized 0.9% NaCl) with NIV. The primary outcome is the percentage of infants with TTN who develop PPHN. The secondary outcomes are the severity of respiratory distress (assessed with the modified TTN Silverman score), frequency of need for intubation, duration of NIV and hospitalization, acid-base balance (blood pH, partial pressure of O₂ and CO₂, and base excess), and blood serum ionogram for Na⁺, K⁺, and Ca²⁺.

DISCUSSION

The Respiratory Failure with Salbutamol (REFSAL) study will be the first clinical trial to evaluate the efficacy and safety of salbutamol in the prevention of persistent pulmonary hypertension in newborns with tachypnea, and will improve short term outcomes. If successful, the study will demonstrate the feasibility of early intervention with NIV/nCPAP together with nebulized salbutamol in the management of TTN.

ETHICS AND DISSEMINATION

The study protocol was approved by the Bioethics Committee of the Medical University of Warsaw, Warsaw, Poland on November 16, 2020 (decision number KB/190/2020). All procedures will follow the principles of the Declaration of Helsinki. The results of the study will be submitted for knowledge translation in peer-reviewed journals and presented at national and international pediatric society conferences.

CLINICAL TRIAL REGISTRATION

It is registered at ClinicalTrials.gov NCT05527704, EudraCT 2020-003913-36; Protocol version 5.0 from 04/01/2022.

Neonatal pulmonary hypertension after severe early-onset fetal growth restriction: post hoc reflections on the Dutch STRIDER study

The aim was to reflect on the unexpected finding of persistent pulmonary hypertension of the neonate (PPHN) and pulmonary hypertension in infants born within the Dutch STRIDER trial, its definition and possible pathophysiological mechanisms. The trial randomly assigned pregnant women with severe early-onset fetal growth restriction to sildenafil 25 mg three times a day versus placebo. Sildenafil use did not reduce perinatal mortality and morbidity, but did result in a higher rate of neonatal pulmonary hypertension (PH). The current paper reflects on the used definition, prevalence, and possible pathophysiology of the data on pulmonary hypertension. Twenty infants were diagnosed with pulmonary hypertension (12% of 163 live born infants). Of these, 16 infants had PPHN shortly after birth, and four had pulmonary hypertension associated with sepsis or bronchopulmonary dysplasia. Four infants with PPHN in the early neonatal period subsequently developed pulmonary hypertension associated with bronchopulmonary dysplasia in later life. Infants with pulmonary hypertension were at lower gestational age at delivery, had a lower birth weight and a higher rate of neonatal co-morbidity. The infants in the sildenafil group showed a significant increase in pulmonary hypertension compared to the placebo group (relative risk 3.67; 95% confidence interval 1.28 to 10.51, P = 0.02).

CONCLUSION

Pulmonary hypertension occurred more frequent among infants of mothers allocated to antenatal sildenafil compared with placebo. A possible pathophysiological mechanism could be a "rebound" vasoconstriction after cessation of sildenafil. Additional studies and data are necessary to understand the mechanism of action.

WHAT IS KNOWN

• In the Dutch STRIDER trial, persistent pulmonary hypertension in the neonate (PPHN) was more frequent among infants after antenatal sildenafil exposure versus placebo.

WHAT IS NEW

• The current analysis focuses on the distinction between PPHN and pulmonary hypertension associated with sepsis or bronchopulmonary dysplasia and on timing of diagnosis and aims to identify the infants at risk for developing pulmonary hypertension. • The diagnosis pulmonary hypertension is complex, especially in infants born after severe early-onset fetal growth restriction. The research field could benefit from an unambiguous consensus definition and standardized screening in infants at risk is proposed.

Persistent Pulmonary Hypertension: A Look Into the Future Therapy

Persistent pulmonary hypertension (PPHN) of the newborn is a lung parenchymal disorder that causes a wide range of hemodynamic changes in the newborn's systemic circulation. Arising from a multifactorial web of etiology, PPHN is one of the most common reasons for neonatal intensive care unit hospitalization and is associated with increased morbidity and mortality. Historically, multiple treatment modalities have been explored, ranging from oxygen and surfactant therapy to newer upcoming medications like magnesium sulfate and adenosine. This review article has discussed the pathogenesis of PPHN and its relationship with the clinical implications of PPHN, such as heart failure and so on. This article has also explored the diagnostic guidelines and analyzed the existing and the upcoming modalities for treating PPHN.

Cost-Utility of Sildenafil for Persistent Pulmonary Hypertension of the Newborn

OBJECTIVE

While advanced therapies for severe persistent pulmonary hypertension of the newborn (PPHN) such as inhaled nitric oxide (iNO) and extracorporeal membrane oxygenation (ECMO) are standard treatments in high-income countries, these therapies are often unavailable in resource-limited settings such as middle-income countries. However, there are small clinical trials illustrating the efficacy of sildenafil at reducing mortality in PPHN. This analysis sought to determine the cost-utility of enteral sildenafil for the treatment of severe PPHN.

STUDY DESIGN

A Markov-state transition model was constructed for the two clinical approaches to compare costs, clinical outcomes, and quality of life: (1) "conventional," (2) "sildenafil." The impact of sildenafil was modeled as a relative risk modifier of the conventional strategy's mortality risk. Transitional probabilities, costs, and utility metrics were extracted from the literature. Sensitivity analyses for each model input as well as 100-patient Monte Carlo simulations were used to test the durability of the model conclusion.

RESULTS

The sildenafil strategy was cost-effective for upper but not lower middle-income countries with an incremental cost-effectiveness ratio of $2,339 per quality-adjusted life year. This conclusion was durable across a wide-range of model assumptions; the sildenafil strategy only failed to meet criteria for cost-effectiveness when sildenafil therapy had a mortality relative risk efficacy of >0.89, if life expectancy in that country is <40 years, or if the lifetime forecasted costs of a survivor's life was quite high.

CONCLUSION

Enteral sildenafil is a cost-effective intervention for severe PPHN for upper middle-income countries where ECMO and iNO are not available.

KEY POINTS

· PPHN is a common life-threatening condition in newborns.. · Sildenafil improves survival of PPHN.. · Sildenafil is cost-effective for upper-middle income countries..

Efficacy and Safety of IV Sildenafil in the Treatment of Newborn Infants with, or at Risk of, Persistent Pulmonary Hypertension of the Newborn (PPHN): A Multicenter, Randomized, Placebo-Controlled Trial

OBJECTIVE

To investigate the efficacy and safety of sildenafil added to inhaled nitric oxide (iNO) for newborn infants with persistent pulmonary hypertension of newborn (PPHN) or hypoxic respiratory failure (HRF) at risk of PPHN.

STUDY DESIGN

Part A of a multinational, randomized, double-blind, placebo-controlled trial. Infants ≤96 hours' old, >34 weeks of gestation, receiving iNO (10-20 ppm on ≥50% FiO₂) for PPHN or HRF at risk of PPHN, and oxygen index >15 to <60, were randomized (1:1) to intravenous (IV) sildenafil (loading: 0.1 mg/kg, over 30 minutes; maintenance: 0.03 mg/kg/h) or placebo, for up to 14 days. Coprimary end points were treatment failure rate (day 14/discharge) and time on iNO without treatment failure. Secondary end points included time on ventilation and oxygenation measures.

RESULTS

Of 87 infants screened, 29 were randomized to IV sildenafil and 30 to placebo; 13 discontinued treatment (sildenafil, n = 6; placebo: n = 7), including 3 deaths (sildenafil: n = 2; placebo: n = 1). Treatment failure rates did not differ with sildenafil (27.6%) vs placebo (20.0%; P = .4935). Mean time on iNO was not different with sildenafil (4.1 days) vs placebo (4.1 days; P = .9850). No differences were noted in secondary end points. Most common adverse events (AEs) with sildenafil (≥10% infants) were hypotension (n = 8/29), hypokalemia (n = 7/29), anemia, drug withdrawal syndrome (n = 4/29, each), and bradycardia (n = 3/29). One serious AE (hypotension) was considered treatment-related.

CONCLUSIONS

IV sildenafil added to iNO was not superior to placebo in infants with PPHN or HRF at risk of PPHN. A review of AEs did not identify any pattern of events indicative of a safety concern with IV sildenafil. Infants will have developmental follow-up (Part B). TRIAL REGISTRATION CLINICALTRIALS.GOV: NCT01720524.

Heat shock protein 70 attenuates hypoxia‑induced apoptosis of pulmonary microvascular endothelial cells isolated from neonatal rats

Pulmonary microvascular endothelial cell (PMVEC) apoptosis is the initial stage of adult pulmonary hypertension (PH), which involves high pulmonary arterial pressure and pulmonary vascular remodeling. However, the mechanism regulating PMVEC apoptosis and its involvement in the early stages of neonatal hypoxic PH (HPH) pathogenesis are currently unclear. The present study aimed to investigate the effects of heat shock protein 70 (HSP70) on hypoxia‑induced apoptosis in PMVECs. PMVECs isolated from neonatal Sprague‑Dawley rats were transfected with lentivirus with or without HSP70, or treated with the synthetic HSP70 inhibitor N‑formyl‑3,4‑methylenedioxy‑benzylidene-g-butyrolactam under hypoxic conditions (5% O2) for 24, 48 or 72 h. PMVEC apoptosis was evaluated by performing flow cytometry and mitochondrial membrane potential (MMP) assays. The expression levels of HSP70, hypoxia‑inducible factor‑1α (HIF‑1α) and apoptosis‑associated proteins were determined by conducting reverse transcription‑quantitative PCR and western blotting. Following 24, 48 or 72 h of hypoxia, the apoptotic rates of PMVECs were significantly elevated compared with cells under normoxic conditions. The MMP was significantly reduced, whereas the mRNA and protein expression levels of HIF‑1α, cytochrome c (cyt C), caspase‑3 and HSP70 were enhanced by hypoxia compared with those under normoxic conditions. Additionally, the mRNA and protein expression levels of B‑cell lymphoma 2 (Bcl‑2) were significantly downregulated in the hypoxia group compared with those in the normoxia group. In hypoxic PMVECs, HSP70 overexpression decreased the apoptotic rate and the expression levels of cyt C, downregulated the expression levels of caspase‑3 and HIF‑1α, and increased the MMP and the expression levels of Bcl‑2. HSP70 inhibition resulted in the opposite outcomes compared with those of HSP70 overexpression. Therefore, the results of the present study suggested that HSP70 may inhibit mitochondrial pathway‑mediated apoptosis in isolated neonatal rat PMVECs in early‑stage hypoxia, which may be associated with HSP70‑mediated HIF‑1α downregulation. Overall, HSP70 may be protective against neonatal HPH through the HSP70/HIF‑1α pathway.

Postnatal causes and severity of persistent pulmonary Hypertension of Newborn

Background & Objective:

Persistent pulmonary hypertension of the newborn (PPHN) is described as severe respiratory failure along with hypoxaemia. PPHN is known to be linked with high morbidity and mortality around the world. This study was planned to determine the postnatal causes and assess the severity of persistent pulmonary hypertension of newborn in babies presenting to the Children’s Hospital, Multan.

Methods:

This observational study was conducted at the Department of Paediatric Cardiology, The Children Hospital &Institute of Child Health, Multan, Pakistan from July to December 2019. A total of 122 confirmed cases of PPHN admitted having gestational age above 34 weeks were enrolled. Demographic data of the newborns was recorded along with maternal medical history, pregnancy status and postnatal causes of PPHN. Severity of PPHN was also recorded.

Results:

Out of a total of 122 cases of PPHN, 81 (66.3%) were male. Majority, 78 (64.0%) had gestational age above 37 weeks. Mode of delivery as cesarean section was noted in 70 (57.4%). Meconium aspiration syndrome 52 (42.6%), birth asphyxia 48 (39.3%), respiratory distress syndrome 23 (18.8%) and sepsis 33 (27.0%) were found to be the commonest causes of PPHN. Severe PPHN was found to be the most frequent, noted among 63 (51.6%) while Moderate PPHN was observed in 40 (32.8%) and Mild PPHN in 19 (15.6%). Morality was noted among 26 (21.3%) of cases.

Conclusion:

Meconium aspiration syndrome, birth asphyxia and respiratory distress syndrome were the commonest postnatal causes of PPHN. Severe PPHN was found to be the most frequent form of PPHN.

Association between genetic variations in carbamoyl-phosphate synthetase gene and persistent neonatal pulmonary hypertension

Persistent pulmonary hypertension of the new-borns (PPHN) is one of the main etiologies of morbidity as well as mortality in neonates. Previous studies found that genetic polymorphisms in urea cycle enzymes are associated with PPHN. Few of the genetic polymorphisms in neonates have been recognized with PPHN. We aimed to find out the prevalence of the CPS-I gene polymorphism and to correlate the genotype with the serum nitric oxide (NO) levels in Egyptian neonates with idiopathic PPHN. We included neonates diagnosed with PPH (n = 150) while the control group included healthy neonates with matched age and sex (n = 100). The CPS-I gene polymorphism: A/C, trans-version substitution, rs4399666 genotype was identified using TaqMan-based quantitative PCR. The results revealed that the CPS-I A/C rs4399666 gene polymorphism and lower serum NO levels were significantly associated with idiopathic PPHN in neonates. In addition, serum NO level was significantly associated with an rs4366999 A/C variant gene in idiopathic PPHN (p = 0.001). Univariable regression analysis demonstrated that there was a significant association between CPS-I A/C rs4399666 CC and increased risk of PPHN (odd ratio, 95% CI of 1.8 (0.78 to 1.75), p-value = 0.04).Conclusion: We concluded that mutant CPS-I A/C rs4399666 minor variant especially the homozygous CC genotype is frequently distributed among the PPHN group. This demonstrates that the presence of mutant CPS-I rs4399666 does not necessarily predispose to the development of PPHN in neonates, but nonetheless, if the C allele is inherited in the homozygous CC genotype, it is associated with a higher risk of PPHN. What is Known: • Prior studies found that polymorphisms in urea cycle enzyme genes are associated with PPHN. • Association between CPS-1 gene polymorphisms is significantly associated with PPHN. What is New: • The prevalence of CPS-1, A/C trans-version substitution, rs4399666 gene polymorphism in Egyptian neonates presented with idiopathic PPHN. • Mutant CPS-I A/C rs4399666 especially the homozygous CC genotype is more frequently distributed among PPHN, and it is significantly associated with low serum nitric oxide level.

Continuous and intermittent administration of intravenous sildenafil in critically ill infants with pulmonary hypertension

Intravenous (IV) sildenafil may be administered as a continuous infusion or intermittent bolus dosing in infants with pulmonary hypertension (PH). We aimed to compare these delivery methods.

METHODS

We retrospectively evaluated subjects less than 12 months old treated with IV sildenafil for PH. Vital signs, oxygen requirement, vasoactive-inotropic score (VIS), and echocardiogram results before and after sildenafil initiation, and the need for discontinuation due to side effects, were noted.

RESULTS

Forty-three subjects were identified (23 continuous, 20 intermittent). There were clinically significant differences in PH classifications between groups. The continuous group was significantly younger (p = 0.010) with higher baseline severity of illness suggested by higher inspired oxygen (FiO₂ ) and VIS (p = 0.012). After sildenafil initiation, there were no significant differences in changes in blood pressure, oxygen saturation, FiO₂ , or VIS between groups, and no difference in the number of subjects requiring discontinuation due to side effects (4 continuous, 1 intermittent, p = 0.351). Eight continuous group subjects (34.8%) and 3 intermittent group subjects (15.0%) died (p = 0.024), but echocardiographic improvement in PH degree was more common in the continuous group (77.8% vs. 33.3%, p = 0.007).

CONCLUSION

In this small cohort of infants treated with continuous or intermittent IV sildenafil, in the setting of different baseline characteristics between groups, there were no significant differences in changes in vital signs, VIS, FiO₂ , or need for discontinuation of therapy due to side effects. Higher continuous group mortality may be explained by greater baseline illness severity, but larger prospective, randomized studies are required to investigate these different delivery methods.

Pathophysiology and Management of Persistent Pulmonary Hypertension of the Newborn

Persistent pulmonary hypertension of the newborn (PPHN) is a disorder of circulatory transition resulting in high pulmonary vascular resistance with extrapulmonary right-to-left shunts causing hypoxemia. There has been substantial gain in understanding of pathophysiology of PPHN over the past 2 decades, and biochemical pathways responsible for abnormal vasoconstriction of pulmonary vasculature are now better understood. Easy availability of bedside echocardiography helps in establishing early definitive diagnosis, understanding the pathophysiology and hemodynamic abnormalities, monitoring the disease process, and response to therapeutic intervention. There also has been significant advancement in specific management of PPHN targeted at deranged biochemical pathways and hemodynamic instability.

Sildenafil for pulmonary hypertension in neonates: An updated systematic review and meta-analysis

OBJECTIVES

To provide an updated review and meta-analysis on the efficacy and safety of sildenafil for treating persistent pulmonary hypertension in neonates (PPHN).

METHODS

PubMed/Medline, SCOPUS, Cochrane Central Register of Controlled Trials, and Web of Science were searched from the inception of publication to January 2021. The principal outcomes include oxygenation parameters, hemodynamic metrics and echocardiographic measurements, as well as adverse outcomes.

RESULTS

A total of eight studies were included with 216 term and premature neonates with PPHN. Compelling evidence showed the use of sildenafil could improve the prognosis of PPHN neonates, compared with baseline or placebo in neonates with PPHN, and a time-dependent pattern of the improvements can be observed. After 24 h of treatment, the Oxygenation index suggested a steady decrease (SD: -1.80, 95% confidence interval [CI]: -2.92, -0.67) and sildenafil exerted peak effects after 72 h of treatment (SD: -4.02, 95% CI: -5.45, -2.59). No clinically significant side effects were identified. Egger's test and funnel plots of the major outcomes were performed, and the publication bias was not significant.

CONCLUSION

Improvements were shown in oxygenation index, pulmonary arterial pressure, and adverse outcomes after using sildenafil for PPHN in neonates. However, future research with robust longitudinal or randomized controlled design is still needed.

Randomized Trial of Oxygen Saturation Targets during and after Resuscitation and Reversal of Ductal Flow in an Ovine Model of Meconium Aspiration and Pulmonary Hypertension

Neonatal resuscitation (NRP) guidelines suggest targeting 85-95% preductal SpO₂ by 10 min after birth. Optimal oxygen saturation (SpO₂) targets during resuscitation and in the post-resuscitation management of neonatal meconium aspiration syndrome (MAS) with persistent pulmonary hypertension (PPHN) remains uncertain. Our objective was to compare the time to reversal of ductal flow from fetal pattern (right-to-left), to left-to-right, and to evaluate pulmonary (Q_PA), carotid (Q_CA)and ductal (Q_DA) blood flows between standard (85-94%) and high (95-99%) SpO₂ targets during and after resuscitation. Twelve lambs asphyxiated by endotracheal meconium instillation and cord occlusion to induce MAS and PPHN were resuscitated per NRP guidelines and were randomized to either standard (85-94%) or high (95-99%) SpO₂ targets. Out of twelve lambs with MAS and PPHN, six each were randomized to standard and high SpO₂ targets. Median [interquartile range] time to change in direction of blood flow across the ductus arteriosus from right-to-left, to left-to-right was significantly shorter with high SpO₂ target (7.4 (4.4-10.8) min) compared to standard SpO₂ target (31.5 (21-66.2) min, p = 0.03). Q_PA was significantly higher during the first 10 min after birth with higher SpO₂ target. At 60 min after birth, the Q_PA, Q_CA and Q_DA were not different between the groups. To conclude, targeting SpO₂ of 95-99% during and after resuscitation may hasten reversal of ductal flow in lambs with MAS and PPHN and transiently increase Q_PA but no differences were observed at 60 min. Clinical studies comparing low and high SpO₂ targets assessing hemodynamics and neurodevelopmental outcomes are warranted.

The newborn sheep translational model for pulmonary arterial hypertension of the neonate at high altitude

Chronic hypoxia during gestation induces greater occurrence of perinatal complications such as intrauterine growth restriction, fetal hypoxia, newborn asphyxia, and respiratory distress, among others. This condition may also cause a failure in the transition of the fetal to neonatal circulation, inducing pulmonary arterial hypertension of the neonate (PAHN), a syndrome that involves pulmonary vascular dysfunction, increased vasoconstrictor tone and pathological remodeling. As this syndrome has a relatively low prevalence in lowlands (~7 per 1000 live births) and very little is known about its prevalence and clinical evolution in highlands (above 2500 meters), our understanding is very limited. Therefore, studies on appropriate animal models have been crucial to comprehend the mechanisms underlying this pathology. Considering the strengths and weaknesses of any animal model of human disease is fundamental to achieve an effective and meaningful translation to clinical practice. The sheep model has been used to study the normal and abnormal cardiovascular development of the fetus and the neonate for almost a century. The aim of this review is to highlight the advances in our knowledge on the programming of cardiopulmonary function with the use of high-altitude newborn sheep as a translational model of PAHN.

Psychiatric Medication Use in Pregnancy and Breastfeeding

Active peripartum psychiatric illness is associated with adverse outcomes for exposed pregnancies/children. Likely due to high rates of obesity, pregnant women with psychiatric illness also have higher rates of preeclampsia, cesarean section, and gestational diabetes. Postpartum depression is associated with lower IQ, slower language development, and behavioral problems in exposed children. Discontinuing psychiatric medications for pregnancy increases risk for relapse significantly, and the postpartum time period is high risk for developing psychiatric illness. Obstetricians-gynecologists are front-line providers for psychiatric care of women during peripartum. This article provides a framework and knowledge base for management of psychiatric illness during peripartum.