Current and future therapeutic options for persistent pulmonary hypertension in the newborn

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

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

Variable role of patent ductus arteriosus

Although patent ductus arteriosus is essential in fetal life, interventions to close or minimize the adverse hemodynamic effects associated with the left-to-right shunt are often needed after birth, especially in extremely premature infants. However, there are clinical conditions where maintaining patency of the ductus is essential for survival. In this article we discuss use of prostaglandin E₁ in the management of congenital heart defects, pulmonary hypertension and left ventricular failure in early neonatal period.

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

It is increasingly recognized that the abnormal physiologic consequences of pulmonary hypertension (PH) may contribute to poor cardiopulmonary health in premature babies. Conflicting literature has led to clinical uncertainty, pathological misinterpretation, and variability in treatment approaches among practitioners. There are several disorders with overlapping and interrelated presentations, and other disorders with a similar clinical phenotype but diverse pathophysiological contributors. In this review, we provide a diagnostic approach for acute hypoxemic respiratory failure in the preterm neonate, outline the pathophysiological conditions that may present as acute PH, and discuss the implications of high pulmonary vascular resistance (PVR) on the cardiovascular system. Although PVR and respiratory management are highly interrelated, there may be a population of preterm neonates in whom inhaled nitric oxide may improve illness severity and may relate to outcomes. A management approach based on physiology that considers common clinical conundrums is provided. A more comprehensive understanding of the physiology may help in informed decision-making in clinical situations where conclusive scientific evidence is lacking. Regardless, high-quality research is required, and appropriate definition of the target population is paramount. A thoughtful approach to cardiovascular therapy may also provide an avenue to improve neurodevelopmental outcomes while awaiting more clear answers.

Endothelin receptor antagonists for persistent pulmonary hypertension in term and late preterm infants

BACKGROUND

Endothelin, a powerful vasoconstrictor, is one of the mediators in the causation of persistent pulmonary hypertension of the newborn (PPHN). Theoretically, endothelin receptor antagonists (ETRA) have the potential to improve the outcomes of infants with PPHN.

OBJECTIVES

To assess the efficacy and safety of ETRA in the treatment of PPHN in full-term, post-term and late preterm infants.To assess the efficacy and safety of selective ETRAs (which block only the ETA receptors) and non-selective ETRAs (which block both ETA and ETB receptors) separately.

SEARCH METHODS

CENTRAL (Cochrane Central Register of Controlled Trials), MEDLINE, EMBASE and CINAHL databases were searched until December 2015.

SELECTION CRITERIA

Randomised, cluster-randomised or quasi-randomised controlled trials were eligible.

DATA COLLECTION AND ANALYSIS

Two review authors independently searched the literature, selected the studies, assessed the risk of bias and extracted the data. A fixed-effect model was used for meta-analysis. We used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to assess the quality of evidence.

MAIN RESULTS

Two randomised controlled trials of ETRA met the inclusion criteria. Both studies utilized oral Bosentan. The first study was done in a setting where inhaled nitric oxide (iNO) therapy was not available. Forty-seven infants (≥ 34 weeks' gestation) were randomised to receive either Bosentan or placebo. The second study was a multicentre study where iNO therapy was the standard of care for PPHN. Twenty-one infants were randomised to receive either 'iNO plus Bosentan' or 'iNO plus placebo'.In the first study, there was no significant difference in the incidence of death before hospital discharge between the Bosentan and placebo groups (1/23 vs 3/14; RR 0.20, 95% CI 0.02 to 1.77; RD -0.17, 95% CI -0.40 to 0.06). A higher proportion of infants in the Bosentan group showed improvement in oxygenation index (OI) at the end of therapy (21/24 vs 3/15; RR 4.38, 95% CI 1.57 to 12.17; RD 0.68, 95% CI 0.43 to 0.92; number needed to treat for a beneficial outcome (NNTB) 1.5). The duration of mechanical ventilation was lower in the Bosentan group (4.3 ± 0.9 vs 11.5 ± 0.6 days; MD -7.20, 95% CI -7.64 to -6.76). There was no significant difference in adverse neurological outcomes at six months (0/23 vs 4/14; RR 0.07, 95% CI 0.00 to 1.20; RD -0.29, 95% CI -0.52 to -0.05). The study suffered from a high risk of attrition bias since 8/23 infants in the placebo group were excluded from various analyses. Since the protocol for the study could not be accessed, the study suffered from unclear risk of reporting bias.In the second study, there was no significant difference in the incidence of treatment failure needing extracorporeal membrane oxygenation (ECMO) between the 'iNO plus Bosentan' vs 'iNO plus placebo' groups (1/13 vs 0/8; RR 1.93, 95% CI 0.09 to 42.35; RD 0.08, 95% CI -0.14 to 0.30). There was no significant difference in the median time to wean from iNO ('iNO plus Bosentan': 3.7 days (95% CI 1.17 to 6.95); 'iNO plus placebo': 2.9 days (95% CI 1.26 to 4.23); P = 0.34). There were no significant differences in the OI 0, 3, 5, 12, 24, 48 and 72 hours of treatment between the groups. There were no significant differences in the time to complete weaning from mechanical ventilation (median 10.8 days (CI 3.21 to 12.21) versus 8.6 days (CI 3.71 to 9.66); P = 0.24). The study had unequal distribution to the Bosentan group (N = 13) and the placebo group (N = 8). The methods used for generating random sequence numbers and allocation concealment were unclear, resulting in unclear risk of selection bias.Both studies reported that Bosentan was well tolerated and no major adverse effects were noted. Data from the two studies was not pooled given the heterogenous nature of the clinical settings and the modalities used for the treatment of PPHN.Overall, the quality of evidence was considered low, given the small sample size of the included studies, the numerical imbalance between the groups due to randomisation and attrition, and unclear risk of bias on some of the important domains.

AUTHORS' CONCLUSIONS

There is inadequate evidence to support the use of ETRAs either as stand-alone therapy or as adjuvant to inhaled nitric oxide in PPHN. Adequately powered RCTs are needed.

Does intravenous sildenafil clinically ameliorate pulmonary hypertension during perioperative management of congenital heart diseases in children? - a prospective randomized study

BACKGROUND

Pulmonary hypertension (PHT), if present, can be a significant cause of increased morbidity and mortality in children undergoing surgery for congenital heart diseases (CHD). Various techniques and drugs have been used perioperatively to alleviate the effects of PHT. Intravenous (IV) sildenafil is one of them and not many studies validate its clinical use.

AIMS AND OBJECTIVES

To compare perioperative PaO 2 - FiO 2 ratio peak filling rate (PFR), systolic pulmonary artery pressure (PAP) - systolic aortic pressure (AoP) ratio, extubation time, and Intensive Care Unit (ICU) stay between two groups of children when one of them is administered IV sildenafil perioperatively during surgery for CHDs.

MATERIALS AND METHODS

Patients with ventricular septal defects and proven PHT, <14 years of age, all American Society of Anesthesiologists physical status III, undergoing cardiac surgery, were enrolled into two groups - Group S (IV sildenafil) and Group C (control) - over a period of 14 months, starting from October 2013. Independent t-test and Mann-Whitney U-test were used to compare the various parameters between two groups.

RESULTS

PFR was higher throughout, perioperatively, in Group S. PAP/AoP was 0.3 and 0.4 in Group S and Group C, respectively. In Group S, mean group extubation time was 7 ± 7.34 h, whereas in Group C it was 22.1 ± 10.6. Postoperative ICU stay in Group S and Group C were 42.3 ± 8.8 h and 64.4 ± 15.9 h, respectively.

CONCLUSION

IV sildenafil, when used perioperatively, in children with CHD having PHT undergoing corrective surgery, improves not only PaO 2 - FiO 2 ratio and PAP - AoP ratio but also reduces extubation time and postoperative ICU stay.

Fetal Anemia With Persistent Pulmonary Hypertension: A Report of 3 Cases

Fetal anemia may cause tissue hypoxia and hence has the potential to predispose to persistent pulmonary hypertension of the newborn (PPHN). Review articles and textbooks do not include severe anemia as a cause of PPHN. We report 3 cases of fetal anemia complicated by severe PPHN.

Risk factors and outcomes of persistent pulmonary hypertension of the newborn in neonatal intensive care unit of Al-minya university hospital in egypt

Background:

Persistent pulmonary hypertension of the newborn (PPHN) result from the failure of the normal fetal-to-neonatal circulatory transition is associated with substantial infant mortality and morbidity.

Objective:

To estimate the possible risk factors and assess the outcome of these cases.

Materials and Methods:

Prospective study was performed enrolling all full-term and post-term newborn admitted to the NICU from January 2009 to April 2012, All neonates were subjected to complete history and physical examination, laboratory data including a complete blood count, arterial blood gases, blood glucose, serum electrolytes, and blood culture to exclude sepsis. Cases with PPHN had a continuous pulse oximeter, blood pressure and electrocardiography monitoring. Chest X-ray and echocardiogarphy were carried out to verify shunt and exclude structural congenital heart disease.

Results:

Out of the studied 640 infants, 32 infants (5%) developed PPHN, Meconium aspiration, birth asphyxia, hyaline membrane diseases, neonatal septicemia, post-term birth being large for gestational age, cesarean section, maternal overweight, and diabetes mellitus were associated with an elevated risk for PPHN. All neonates treated with O₂, 10 neonates with Mg sulphate, 16 with oral sildenafil and 12 with mechanical ventilation. After 6 months follow-up, 12 (37.54%) improved and followed-up without sequelae, 4 (12.5%) developed some neurodevelopmental impairment, 8 (25%) died, 3 (9.3%) developed chronic lungs diseases, 2 (6.2%) developed hearing defects and another 3 (9.3%) missed follow-up.

Conclusion:

PPHN was found in 5% of the studied population. Meconium aspiration, birth asphyxia, neonatal septicemia, post-term were associated with an elevated risk for PPHN. As this is a unit based study, a comprehensive countrywide survey on PPHN in Egypt is recommended to determine any regional differences in disease incidence.

Pathophysiology, management, and outcome of persistent pulmonary hypertension of the newborn: a clinical review

Persistent Pulmonary Hypertension of the Newborn (PPHN) results from the failure of relaxation of the pulmonary vasculature at birth, leading to shunting of non-oxygenated blood from the pulmonary to the systemic circulation. More often, full term and near-term infants are affected, however it is not uncommon to see PPHN in preterm infants who have respiratory distress syndrome. In some infants pulmonary vascular remodeling is present at birth, pointing toward the prenatal onset of the disease process. Regardless of the etiology, PPHN should be diagnosed and treated as soon as possible to avoid hypoxia related short term and long-term morbidities. The mainstay therapy is the treatment of the underlying condition along with several promising therapeutic modalities such as oxygen supplementation, mechanical ventilation, nitric oxide, phosphodiesterase inhibitors, prostaglandins analogs, endothelin receptor antagonists, and extracorporeal membrane oxygenation. The optimal approach to the management of PPHN remains controversial. After discharge from the NICU, infants with PPHN warrant long-term follow up since they are at risk for neurodevelopmental disabilities and chronic health conditions.

Causes of death in infants admitted to Australian neonatal intensive care units between 1995 and 2006

AIM

To compare causes and rates of mortality among infants admitted to 10 Australian neonatal intensive care units (NICUs) between 1995 and 2006.

METHODS

De-identified perinatal data from the Neonatal Intensive Care Units' (NICUS) Data Collection for 24 131 infants were examined for causes and rates of death. The study period was divided into two epochs: I (1995-2000, n = 11 185 infants) and II (2001-2006, n = 12 946 infants).

RESULTS

A total of 2224 (9.2%) infants died in hospital. Mortality decreased from 10.3% (1152/11 185) in epoch I to 8.3% (1072/12 946) in epoch II (p < 0.001) due to improved survival in term infants. Extreme prematurity also decreased as a primary cause of death (118 (10.2%) vs 76 (7.1%), p = 0.008). No infant >42-week gestation was admitted in epoch II. Congenital abnormalities were the most common cause of death (>20%) in both epochs, mostly in term rather than preterm infants (40.7% vs 13.9%, p < 0.001). Age of death was unchanged between the two epochs (median 4, 1st, 3rd quartiles: 1,16 days).

CONCLUSION

Mortality rates have continued to decrease but improvement is predominantly due to improved survival of term infants and prevention of postdate deliveries. Congenital abnormalities continue to be the most common cause of death.

Inhaled epoprostenol therapy for pulmonary hypertension: Improves oxygenation index more consistently in neonates than in older children

The purpose of this study was to determine the efficacy of inhaled epoprostenol for treatment of acute pulmonary hypertension (PH) in pediatric patients and to formulate a plan for a prospective, randomized study of pulmonary vasodilator therapy in this population. Inhaled epoprostenol is an effective treatment for pediatric PH. A retrospective chart review was conducted of all pediatric patients who received inhaled epoprostenol at a tertiary care hospital between October 2005 and August 2007. The study population was restricted to all patients under 18 years of age who received inhaled epoprostenol for greater than 1 hour and had available data for oxygenation index (OI) calculation. Arterial blood gas values and ventilator settings were collected immediately prior to epoprostenol initiation, and during epoprostenol therapy (as close to 12 hours after initiation as possible). Echocardiograms were reviewed during two time frames: Within 48 hours prior to therapy initiation and within 96 hours after initiation. Of the 20 patients in the study population, 13 were neonates, and the mean OI for these patients improved during epoprostenol administration (mean OI before and during therapy was 25.6±16.3 and 14.5±13.6, respectively, P=0.02). Mean OI for the seven patients greater than 30 days of age was not significantly different during treatment (mean OI before and during therapy was 29.6±15.0 and 25.6±17.8, P=0.56). Improvement in echocardiographic findings (evidence of decreased right-sided pressures or improved right ventricular function) was demonstrated in 20% of all patients. Inhaled epoprostenol is an effective therapy for the treatment of selected pediatric patients with acute PH. Neonates may benefit more consistently from this therapy than older infants and children. A randomized controlled trial is needed to discern the optimal role for inhaled prostanoids in the treatment of acute PH in childhood.

Epigenetic regulation of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is diagnosed as a sustained elevation of pulmonary arterial pressure to more than 25 mm Hg at rest or to more than 30 mm Hg with exercise. PAH is an intrinsic disease of the pulmonary vascular smooth muscle and endothelial cells in association with plexiform lesions, medial thickening, concentric laminar intimal fibrosis and thrombotic lesions. Pulmonary vascular remodeling is the characteristic pathological change of PAH. The pathogenesis of PAH has been studied at the level of smooth muscle and endothelial cells. Existing research does not adequately explain susceptibility to the disease, and recent evidence reveals that epigenetic alterations may be involved in PAH. Epigenetics refers to all heritable changes in phenotype or in gene expression states, including chromatin remodeling, DNA methylation, histone modification and RNA interference, which are not involved in the DNA sequence itself. This review will focus on recent advances in epigenetics related to PAH, including epigenetic changes of superoxide dismutase, endothelial nitric oxide synthase and the bone morphogenetic protein signaling pathway. This will provide new insight for improved treatment and prevention of PAH. Future work aimed at specific epigenetic treatments may prove to be an effective therapy for patients with PAH.