The effect of milrinone on right and left ventricular function when used as a rescue therapy for term infants with pulmonary hypertension

Milrinone in persistent pulmonary hypertension of newborn: a scoping review

Persistent pulmonary hypertension of the newborn (PPHN) is a common neonatal condition in newborns admitted to the neonatal intensive care units (NICUs). PPHN has still a high mortality and morbidity. Inhaled nitric oxide (iNO) is the first line vasodilator therapy for PPHN in high income countries. In low-to-middle income countries (LMICs), availability of iNO remains scarce and expensive. The purpose of this scoping review was to evaluate the current existing literature for milrinone therapy in PPHN and to identify the knowledge gaps in milrinone use in infants with PPHN. The available evidence for milrinone remains limited both as monotherapy and as an adjuvant to iNO. The studies were heterogeneous, conducted in different settings, with different populations and more importantly the endpoints of these trials were short-term outcomes such as changes in oxygenation and blood pressure. Large prospective studies investigating long-term outcomes, mortality, and the need for Extracorporeal membrane oxygenation (ECMO) are warranted. Randomized controlled trials with milrinone as monotherapy are needed in LMICs where iNO availability remains limited. IMPACT: Milrinone has a potential role in the management of PPHN both as an adjuvant to iNO as well as a monotherapy. This scoping review identified the problems existing in the published literature on milrinone and the barriers to generalization of these results. Multi-centre randomized controlled trials on milrinone, especially involving centers from low- and middle-income countries are needed, where it can be evaluated as first-line pulmonary vasodilator therapy.

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.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Impact of persistent pulmonary hypertension and oxygenation on brain injury in neonates with neonatal encephalopathy treated with therapeutic hypothermia

OBJECTIVE

To investigate the effects of persistent pulmonary hypertension (PPHN) and oxygenation on outcome of neonates with neonatal encephalopathy (NE) treated with therapeutic hypothermia (TH).

STUDY DESIGN

We compared the outcome of neonates with NE treated with TH with or without PPHN.

RESULTS

384 neonates with NE were treated with TH; 24% had PPHN. The fraction of inspired oxygen was higher in the first 4 days of life (p < 0.001) in neonates with PPHN. They had a significantly lower arterial partial pressure of oxygen in the first 4 days of life (p = 0.005) and higher on days 3-4 of life (p < 0.001). They were more often intubated (p < 0.001) and more often had concomitant hypotension (p < 0.001). They had higher mortality (p = 0.009) and more often developed brain injury (p = 0.02).

CONCLUSION

PPHN occurred frequently in neonates with NE treated with TH and was associated with a higher incidence of adverse outcome.

Targeted Neonatal Echocardiography in the Management of Neonatal Pulmonary Hypertension

Pulmonary hypertension (PH) in neonates, originating from a range of disease states with heterogeneous underlying pathophysiology, is associated with significant morbidity and mortality. Although the final common pathway is a state of high right ventricular afterload leading to compromised cardiac output, multiple hemodynamic phenotypes exist in acute and chronic PH, for which cardiorespiratory treatment strategies differ. Comprehensive appraisal of pulmonary pressure, pulmonary vascular resistance, cardiac function, pulmonary and systemic blood flow, and extrapulmonary shunts facilitates delivery of individualized cardiovascular therapies in affected newborns.

Inhaled Nitric Oxide in Neonatal Pulmonary Hypertension

Pivotal trials investigating the use of inhaled nitric oxide (iNO) in the 1990s led to approval by the Food and Drug Administration in 1999. Inhaled nitric oxide is the only approved pulmonary vasodilator for persistent pulmonary hypertension of the newborn (PPHN). Selective pulmonary vasodilation with iNO in near-term and term neonates with PPHN is safe, and targeted use of iNO in less mature neonates with pulmonary hypertension (PH) can be beneficial. This review addresses a brief history of iNO, clinical features of neonatal PH, and the clinical application of iNO.

Targeted Therapies for Neonatal Pulmonary Hypertension: Beyond Nitric Oxide

Pulmonary hypertension in the neonatal population can be acute or chronic and carries significant risk for morbidity and mortality. It can be idiopathic but more often is associated with comorbid pulmonary and heart disease. There are several pharmacotherapeutics aimed at pulmonary vasodilation. This review highlights the most common agents as well as those on the horizon for the treatment of pulmonary hypertension in the neonate.

Reassessing the role of milrinone in the treatment of heart failure and pulmonary hypertension in neonates and children: a systematic review and meta-analysis

To evaluate milrinone's impact on pediatric cardiac function, focusing on its specific role as an inotrope and lusitrope, while considering its systemic and pulmonary vasodilatory effects. Search of PubMed, EMBASE, and the Cochrane Library up to August 2023. We included all studies that evaluated milrinone in children under 18 years old in neonatal, pediatric, or cardiac intensive care units. We excluded case reports, studies that did not provide tabular information on milrinone's outcomes, and studies focused on non-intensive care populations. We extracted data on the research design, objectives, study sample, and results of each study, including the impact of milrinone and any associated factors. We screened a total of 9423 abstracts and 41 studies were ultimately included. Milrinone significantly improved left ventricular ejection fraction (WMD 3.41 [95% CI 0.61 - 6.21]), left ventricle shortening fraction (WMD 4.25 [95% CI 3.43 - 5.08]), cardiac index (WMD 0.50 [95% CI 0.32 to 0.68]), left ventricle output (WMD 55.81 [95% CI 4.91 to 106.72]), serum lactate (WMD -0.59 [95% CI -1.15 to -0.02]), and stroke volume index (WMD 2.95 [95% CI 0.09 - 5.82]). However, milrinone was not associated with improvements in ventricular myocardial performance index (WMD -0.01 [95% CI -0.06 to 0.04]) and ventricular longitudinal strain (WMD -2.14 [95% CI -4.56 to 0.28]). Furthermore, milrinone was not associated with isovolumetric relaxation time reduction (WMD -8.87 [95% CI -21.40 to 3.66]).

CONCLUSION

Our meta-analysis suggests potential clinical benefits of milrinone by improving cardiac function, likely driven by its systemic vasodilatory effects. However, questions arise about its inotropic influence and the presence of a lusitropic effect. Moreover, milrinone's pulmonary vasodilatory effect appears relatively weaker compared to its systemic actions. Further research is needed to elucidate milrinone's precise mechanisms and refine its clinical applications in pediatric practice.

WHAT IS KNOWN

• Milrinone is a phosphodiesterase III inhibitor that has been used to treat a variety of pediatric and neonatal conditions. • Milrinone is believed to exert its therapeutic effects by enhancing cardiac contractility and promoting vascular relaxation.

WHAT IS NEW

• Milrinone may not have a significant inotropic effect. • Milrinone's pulmonary vasodilatory effect is less robust than its systemic vasodilatory effect.

Case Report: Stüve-Wiedemann syndrome-a rare cause of persistent pulmonary hypertension of the newborn

Introduction

Persistent pulmonary hypertension of the newborn (PPHN) is a life-threatening condition characterized by hypoxemia due to elevated pulmonary vascular resistance. PPHN commonly arises secondary to various underlying conditions, including infection, meconium aspiration, and respiratory distress syndrome. Management includes pulmonary vasodilators, mechanical ventilation, oxygen supplementation, vasopressors, and volume replacement. Stüve-Wiedemann syndrome (SWS), a rare genetic disorder characterized by bone dysplasia, respiratory distress, hyperthermia, and swallowing difficulties, may present with pulmonary hypertension, indicating a poor prognosis.

Case description

A term female neonate presented with secondary respiratory failure and severe PPHN of unknown etiology on the second day of life, necessitating intubation. Clinical findings included facial dysmorphia, camptodactyly, skeletal anomalies, and generalized muscular hypotonia. High-frequency oscillation ventilation and surfactant administration yielded marginal improvement. On the third day of life, a severe pulmonary hypertensive crisis necessitated inhaled and systemic pulmonary vasodilators along with volume and catecholamine therapy. Whole exome sequencing revealed a homozygous mutation in the leukemia inhibitory factor receptor (LIFR) gene, consistent with Stüve-Wiedemann syndrome.

Discussion/conclusion

The case underscores the importance of considering and prompting evaluation of rare genetic causes in the differential diagnosis of PPHN, especially when other abnormalities are present and conventional therapies prove inadequate. Therapeutic strategies must account for the different pathophysiology of primary PPHN including vascular remodeling, as seen in SWS, which may not respond to pulmonary vasodilators typically employed in secondary PPHN due to vasoconstriction. In this case, the patient responded well to treatment for primary PPHN, but the use of high-frequency oscillation ventilation and surfactant was not helpful.

The early use of inhaled nitric oxide in premature infants requiring respiratory support

Background: Earlier studies on the use of inhaled nitric oxide (iNO) for premature infants born at <34 weeks of gestation requiring respiratory support did not provide conclusive evidence of benefit. National guidelines generally discouraged the use in this population. More recent national guidelines endorsed the use of iNO in premature infants with hypoxic respiratory failure (HRF) associated with persistent pulmonary hypertension of the newborn (PPHN).Recent Studies: Two recently published observational studies evaluated the effect of administering iNO on oxygenation in the first week of life. These studies compared premature infants born at the gestational age (GA) of <34 weeks with HRF associated with PPHN to term and late preterm infants born at the GA of ≥34 weeks who received iNO. Both studies showed a similar effect of iNO on oxygenation in the two infant cohorts. The response rate in the premature infant cohort was 59% in the first study and 90% in the second. The mean response time was 9.2 h and 10.3 h, and the mean duration of therapy was 3.5 days and 8.2 days, respectively.Conclusion: The results of these studies support a trial of iNO in premature infants with persistent hypoxia despite optimum respiratory support. Obtaining a timely echocardiogram to exclude cardiac diseases and diagnose PPHN is logistically challenging for many clinicians, thus, a clinical diagnosis of PPHN might have to be made in these situations. Questions remain regarding the optimum dose of iNO and the duration of the initial iNO trial in these patients.KEY MESSAGESIn the most recently published studies, the improvement of oxygenation in iNO-treated infants born at <34 weeks of gestation with HRF and PPHN physiology was as effective as in infants born ≥34 weeks.These studies provide evidence supporting a trial of iNO in the subpopulation of premature infants with HRF associated with PPHN.

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..

Comparison of the efficacy of inhaled versus infused milrinone in the management of persistent pulmonary hypertension of the newborn in resource-limited settings: A randomized clinical trial

BACKGROUND

The standard treatment for persistent pulmonary hypertension of the newborn (PPHN) is inhaled nitric oxide (iNO), which is not available in Iran. Consequently, other drugs, such as milrinone, are prescribed. So far, no study has investigated the effectiveness of inhaled milrinone in the management of PPHN. The present study aimed to improve the management of PPHN in the absence of iNO.

METHODS

In this randomized clinical trial, neonates with PPHN, admitted to the neonatal intensive care unit of Hazrat Ali-Asghar and Akbar-Abadi hospitals, were treated with intravenous dopamine infusion and randomly divided into two groups, receiving milrinone through inhalation or infusion rout. The neonates were evaluated by Doppler echocardiography, clinical examinations, and oxygen demand test. The neonates were also evaluated for the clinical symptoms and mortality in the follow-up.

RESULTS

A total of 31 infants, with a median age of 2 days (interquartile range = 4), were included in this study. There was a significant decrease in the peak systolic and mean pulmonary arterial pressure in both inhalation and infusion groups following milrinone administration, with no significant difference between the groups (p = 0.584 and p = 0.147, respectively). There was no significant difference between the two groups regarding the mean systolic blood pressure before and after treatment. Additionally, diastolic blood pressure was significantly lower in the infusion group after treatment (p = 0.020); however, the amount of reduction was not significantly different between the groups (p = 0.928). Overall, 83.9% of the participants achieved full recovery, 75% of whom were in the infusion group and 93.3% in the inhalation group (p = 0.186).

CONCLUSION

Milrinone inhalation can have similar effects to milrinone infusion as an adjunct treatment in the management of PPHN. Also, infusion and inhalation of milrinone showed similar safety.

How to diagnose and treat acute pulmonary hypertension when you have no cardiology support

Acute pulmonary hypertension (aPH) is a complex, physiology-driven disorder that causes critical illness in newborns, the hallmark of which is elevated pressure in the pulmonary vascular bed. Several underlying hemodynamic phenotypes exist, including classic arterial aPH with resistance-driven elevations in pulmonary arterial pressure (PAP), alongside flow-driven aPH from left-to-right shunt lesions, and primary left ventricular dysfunction with pulmonary venous hypertension and elevated left atrial pressure. Targeted neonatal echocardiography (TnECHO) is an important tool for evaluation of hemodynamics in aPH and is highly useful for evaluating modulators of disease and targeting cardiovascular therapy. The diagnostic approach to aPH includes confirmation of elevation of PAP, evaluation of the cause and exclusion of structural cardiac disease, assessment of the response of the myocardium to adverse loading conditions, and appraisal of the adequacy of systemic blood flow. Therapeutic goals include support of right ventricular (RV) function, RV afterload reduction, and selection of cardiotropic agents that support underlying pathophysiology without adverse effects on heart rate or pulmonary vascular resistance in addition to routine supportive intensive care. Training programs for TnECHO exist across multiple jurisdictions and strong correlation with pediatric cardiology assessment has been demonstrated. Future directions include adapting TnECHO training with a greater focus on achieving competency, and further research into the role of the modality in providing individualized cardiovascular care for patients with heterogenous underlying physiology, and its effect on key neonatal outcomes.

Pulmonary vasodilator strategies in neonates with acute hypoxemic respiratory failure and pulmonary hypertension

The management of acute hypoxemic respiratory failure (AHRF) in newborns continues to be a clinical challenge with elevated risk for significant morbidities and mortality, especially when accompanied with persistent pulmonary hypertension of the newborn (PPHN). PPHN is a syndrome characterized by marked hypoxemia secondary to extrapulmonary right-to-left shunting across the ductus arteriosus and/or foramen ovale with high pulmonary artery pressure and increased pulmonary vascular resistance (PVR). After optimizing respiratory support, cardiac performance and systemic hemodynamics, targeting persistent elevations in PVR with inhaled nitric oxide (iNO) therapy has improved outcomes of neonates with PPHN physiology. Despite aggressive cardiopulmonary management, a significant proportion of patients have an inadequate response to iNO therapy, prompting consideration for additional pulmonary vasodilator therapy. This article reviews the pathophysiology and management of PPHN in term newborns with AHRF while highlighting both animal and human data to inform a physiologic approach to the use of PH-targeted therapies.

Management Practices During Perinatal Respiratory Transition of Very Premature Infants

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

Pulmonary Vasodilator Therapy in Persistent Pulmonary Hypertension of the Newborn

Inhaled nitric oxide (iNO) therapy had a transformational impact on the management of infants with persistent pulmonary hypertension of the newborn (PPHN). iNO remains the only approved pulmonary vasodilator for PPHN; yet 30% to 40% of patients do not respond or have incomplete response to iNO. Lung recruitment strategies with early surfactant administration and high-frequency ventilation can optimize the response to iNO in the presence of parenchymal lung diseases. Alternate pulmonary vasodilators are used commonly as rescue, life-saving measures, though there is a lack of high-quality evidence supporting their efficacy and safety. This article reviews the available evidence and future directions for research in PPHN.

Worsened short-term clinical outcomes in a cohort of patients with iNO-unresponsive PPHN: a case for improving iNO responsiveness

OBJECTIVES

To identify distinguishing characteristics of neonates with persistent pulmonary hypertension of the newborn (PPHN) unresponsive to inhaled nitric oxide (iNO) and evaluate the use of milrinone in this cohort.

STUDY DESIGN

Retrospective chart review of 99 neonates with PPHN treated with iNO over a five-year period at a quaternary neonatal intensive care unit.

RESULTS

Neonates with iNO-unresponsive PPHN had an increased number of ventilator days (10 vs 7 days, p = 0.02), greater length of hospital stay (30 vs 22 days, p = 0.02), and increased risk of death or ECMO than iNO-responsive neonates (p = 0.03). Inhaled NO non-responders treated with milrinone had improved oxygenation (p < 0.03) and no change in systemic hemodynamics.

CONCLUSION

Neonates with iNO-unresponsive PPHN had worse clinical outcomes than iNO responders. Milrinone may be a safe and effective adjuvant therapy, although large-scale studies are lacking. Identifying early predictors of iNO response and novel strategies to enhance iNO responsiveness should be prioritized.

Predicting treatment of pulmonary hypertension at discharge in infants with congenital diaphragmatic hernia

OBJECTIVE

To predict pulmonary hypertension (PH) therapy at discharge in a large multicenter cohort of infants with congenital diaphragmatic hernia (CDH).

STUDY DESIGN

Six-year linked records from Children's Hospitals Neonatal Database and Pediatric Health Information System were used; patients whose diaphragmatic hernia was repaired before admission or referral, who were previously home before admission or referral, and non-survivors were excluded. The primary outcome was the use of PH medications at discharge and the secondary outcome was an inter-center variation of therapies during inpatient utilization. Clinical factors were used to develop a multivariable equation randomly applied to 80% cohort; validated in the remaining 20% infants.

RESULTS

A total of 831 infants with CDH from 23 centers were analyzed. Overall, 11.6% of survivors were discharged on PH medication. Center, duration of mechanical ventilation, and duration of inhaled nitric oxide were associated with the use of PH medication at discharge. This model performed well in the validation cohort area under the receiver operating characteristic curve of 0.9, goodness-of-fit χ², p = 0.17.

CONCLUSIONS

Clinical variables can predict the need for long-term PH medication after NICU hospitalization in surviving infants with CDH. This information may be useful to educate families and guide the development of clinical guidelines.

Hemodynamic response to milrinone for refractory hypoxemia during therapeutic hypothermia for neonatal hypoxic ischemic encephalopathy

OBJECTIVE

Characterize the impact of milrinone on arterial pressure of neonates with persistent hypoxemic respiratory failure (HRF) and hypoxic ischemic encephalopathy (HIE) treated with inhaled nitric oxide and therapeutic hypothermia (TH).

STUDY DESIGN

Retrospective cohort study. Arterial pressure was assessed hourly for 24 h. The primary outcome was change in diastolic arterial pressure (DAP).

RESULTS

56 patients were included [(i) cases: HIE/TH who received milrinone (n = 9), (ii) Milrinone controls (n = 17), (iii) HIE controls (n = 30)]. Baseline demographics, severity of HRF and arterial pressure were comparable between groups. Only milrinone treated patients with HIE/TH had a marked drop in DAP in the first hour, which persisted for more than 12 h despite escalation in inotropes (p = 0.008).

CONCLUSION

Milrinone treated patients with HRF and HIE/TH develop profound reduction in DAP and require escalation of cardiovascular support. The risk benefit profile of milrinone should be considered and pharmacological studies are warranted to evaluate drug metabolism and clearance in this population.

Management of systemic hypotension in term infants with persistent pulmonary hypertension of the newborn: an illustrated review

In persistent pulmonary hypertension of the newborn (PPHN), the ratio of pulmonary vascular resistance to systemic vascular resistance is increased. Extrapulmonary shunts (patent ductus arteriosus and patent foramen value) allow for right-to-left shunting and hypoxaemia. Systemic hypotension can occur in newborns with PPHN due to variety of reasons, such as enhanced peripheral vasodilation, impaired left ventricular function and decreased preload. Systemic hypotension can lead to end organ injury from poor perfusion and hypoxaemia in the newborn with PPHN. Thus, it must be managed swiftly. However, not all newborns with PPHN and systemic hypotension can be managed the same way. Individualised approach based on physiology and echocardiographic findings are necessary to improve perfusion to essential organs. Here we present a review of the physiology and mechanisms of systemic hypotension in PPHN, which can then guide treatment.

Congenital diaphragmatic hernia: a narrative review of controversies in neonatal management

The consequences of most hernias can be immediately corrected by surgical repair. However, this isn't always the case for children born with a congenital diaphragmatic hernia. The derangements in physiology encountered immediately after birth result from pulmonary hypoplasia and hypertension caused by herniation of abdominal contents into the chest early in lung development. This degree of physiologic compromise can vary from mild to severe. Postnatal management of these children remains controversial. Although heavily studied, multi-institutional randomized controlled trials are lacking to help determine what constitutes best practice. Additionally, the results of the many studies currently within the literature that have investigated differing aspect of care (i.e., inhaled nitric oxide, ventilator type, timing of repair, role of extracorporeal membrane oxygenation, etc.) are difficult to interpret due to the small numbers investigated, the varying degree of physiologic compromise, and the contrasting care that exists between institutions. The aim of this paper is to review areas of controversy in the care of these complex kids, mainly: the use of fraction of inspired oxygen, surfactant therapy, gentle ventilation, mode of ventilation, medical management of pulmonary hypertension (inhaled nitric oxide, sildenafil, milrinone, bosentan, prostaglandins), the utilization of extracorporeal membrane oxygenation, and the timing of surgical repair.

Persistent pulmonary hypertension of the newborn

Persistent pulmonary hypertension of the newborn (PPHN) is a significant clinical problem characterized by refractory and severe hypoxemia secondary to elevated pulmonary vascular resistance resulting in right-to-left extrapulmonary shunting of deoxygenated blood. PPHN is associated with diverse cardiopulmonary disorders and a high early mortality rate for infants with severe PPHN. Surviving infants with PPHN have an increased risk of long-term morbidities. PPHN physiology can be categorized by (1) maladaptation: pulmonary vessels have normal structure and number but have abnormal vasoreactivity; (2) excessive muscularization: increased smooth muscle cell thickness and increased distal extension of muscle to vessels that are usually not muscularized; and (3) underdevelopment: lung hypoplasia associated with decreased pulmonary artery number. Treatment involves adequate lung recruitment, optimization of cardiac output and left ventricular function, and pulmonary vasodilators such as inhaled nitric oxide. Infants who fail to respond to conventional therapy should be evaluated for lethal lung disorders including alveolar-capillary dysplasia, T-box transcription factor 4 gene, thyroid transcription factor-1, ATP-binding cassette A3 gene, and surfactant protein diseases.

Cardiac Function and Ventricular Interactions in Persistent Pulmonary Hypertension of the Newborn

OBJECTIVES

The aim of this study was to use a comprehensive imaging protocol to identify echocardiographic correlations of right and left ventricular size, function, and hemodynamics in neonates with persistent pulmonary hypertension of newborn and describe their relationship with key clinical variables.

DESIGN

Retrospective case-control echocardiography-based study of persistent pulmonary hypertension of newborn.

SETTING

A tertiary neonatal ICU in Canada.

PATIENTS

Forty-nine neonates (gestational age ≥ 35 wk old) diagnosed with persistent pulmonary hypertension of newborn within first 3 days after birth and 50 age-matched controls.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The echocardiographic measurements comprised of right ventricular and left ventricular functional markers, including tricuspid annular plane systolic excursion, fractional area change, tissue Doppler imaging, and deformation imaging. Sample size was based on detecting an intergroup difference of 10% in tricuspid annular plane systolic excursion, which was considered the primary outcome. Linear correlations between the right and left ventricular indices, as well as their association with the outcome of death or extracorporeal membrane oxygenation were evaluated. Persistent pulmonary hypertension of newborn was associated with lower tricuspid annular plane systolic excursion (6.81 ± 1.92 vs 9.25 ± 1.30 mm), right-ventricular global longitudinal strain (16.9% ± 5.4% vs -21.6% ± 4.6%); left ventricular ejection fraction (49% ± 7% vs 55% ± 6%), left ventricular global longitudinal strain (-16.7% ± 3.3% vs -21.4% ± 2.0%) (all p < 0.01). Right and left ventricular diastolic and global function was also lower in persistent pulmonary hypertension of newborn, with more pronounced changes seen for the right ventricle. Moderate-to-strong linear correlations were observed between the right and left ventricular functional markers, with right ventricular global longitudinal strain and left ventricular global longitudinal strain being the strongest (r = 0.8). Within persistent pulmonary hypertension of newborn group, hypoxic ischemic encephalopathy was associated with lower right and left ventricular systolic and right ventricular diastolic performance. Tricuspid annular plane systolic excursion (p =0.08) and left ventricular systolic velocity (p = 0.09) tended to be lower in patients who subsequently died/needed extracorporeal membrane oxygenation.

CONCLUSIONS

Persistent pulmonary hypertension of newborn is characterized by global cardiac dysfunction, involving both the right and left ventricles, with significant interventricular functional correlation. Cardiac dysfunction early in disease course may identify patients at highest risk of adverse outcome.

Milrinone Use in Persistent Pulmonary Hypertension of the Newborn

Failure of the normal transition from in utero to ex utero physiology leads to "persistent" pulmonary hypertension of the newborn (PPHN). PPHN is frequently associated with low systemic blood pressure and low cardiac output because of increased right ventricular afterload and myocardial dysfunction. The general management of newborns with PPHN is geared toward maintenance of normothermia, normal serum electrolytes, normal intravascular volume, correction of acidosis, adequate sedation/analgesia, adequate ventilation and oxygenation with optimal lung recruitment, and avoidance of hyperoxia. Inotropic and vasoactive agents are commonly initiated early to increase cardiac output, maintain adequate systemic blood pressure, and enhance oxygen delivery to the tissue. Unfortunately, there is not much evidence on the choice, timing of initiation, dosing, monitoring, and titrating of vasoactive agents in this patient population. In this review, we will discuss the pathophysiology of PPHN and review the use of inotropic, lusitropic, and vasoactive agents in the management of PPHN, with particular attention to milrinone.

The myocardial protective effect of monosodium phosphate cardioplegia in cardiopulmonary bypass in infants with an atrial septal defect

This study aimed to investigate the myocardial protective effect of liquid sodium phosphocreatine cardiac arrest in extracorporeal circulation surgery treating infants with atrial septal defects.Eighty-four infants with atrial septal defects who required extracorporeal circulation surgery treatment at our hospital from January 2016 to June 2018 were divided into an observation group and a control group through a digitally randomized method, with 42 cases in each group. The control group adopted the conventional modified St Thomas II high potassium cold liquid crystal cardiac arrest, while the observation group adopted the liquid sodium phosphocreatine cardiac arrest.The myocardial enzyme indexes of the 2 groups 3, 6, 12, and 24 hours postoperatively were higher than before establishing the cardiopulmonary bypass and the enzyme indexes of the control group at the same time were higher than that of the observation group; adenosine triphosphate, adenosine diphosphate, and other energy levels and the postoperative recovery rate energy levels of the observation group were higher than those in the control group, the difference was statistically significant (P < .05).Liquid sodium phosphocreatine cardiac arrest used in extracorporeal circulation surgery treating infants with atrial septal defects can reduce myocardial ischemia-reperfusion injury, maintain energy supply during ischemia, strengthen the St Thomas II effect, and aid postoperative cardiac function recovery of high potassium cold liquid crystal cardiac arrest used in infants with atrial septal defects and treated with extracorporeal circulation surgery.

The effect of milrinone on hemodynamic and gas exchange parameters in children

Milrinone is a drug frequently used for hemodynamic support in children during critical illness. Although the hemodynamic changes induced by milrinone in children may appear similar to those of adults, the physiologic contributors of these changes remain vastly unknown. A systematic review was conducted to identify studies characterising the hemodynamic effects of milrinone in children during critical illness for hemodynamic support for various medical conditions. Studies were assessed for quality and those of satisfactory quality with pre- and post-operative hemodynamics for each patient were included in the final analyses. Those not limited to children and those not limited to patients with critical illness were excluded from the final analyses. A total of six studies with 791 patients were included in the final analyses. Milrinone infusion doses ranged from 0.3 to 0.75 mcg/kg/minute with the mean infusion dose being 0.5 mcg/kg/minute. Patients whom received milrinone infusion had greater cardiac output, greater left ventricle shortening fraction, lower right ventricular systolic pressure, and lower serum lactate levels. Systolic blood pressure mean arterial blood pressure and arterial oxygen concentration did not significantly change with administration of milrinone. These results were irrespective of milrinone infusion dose, infusion duration, and study size. Milrinone was found to have several beneficial hemodynamic effects in children during critical illness when used at usual clinical doses.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

The Use of Cardiotonic Drugs in Neonates

There is a distinct lack of age-appropriate cardiotonic drugs, and adult derived formulations continue to be administered, without evidence-based knowledge on their dosing, safety, efficacy, and long-term effects. Dopamine remains the most commonly studied and prescribed cardiotonic drug in the neonatal intensive care unit (NICU), but evidence of its effect on endorgan perfusion still remains. Unlike adult and pediatric critical care, there are significant gaps in our knowledge on the use of various cardiotonic drugs in various forms of circulatory failure in the NICU.

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

Persistent pulmonary hypertension of the newborn (PPHN) is a relatively common condition which results in a mortality of up to 33%. Up to 40% of infants treated with nitric oxide (iNO) either have a transient response or fail to demonstrate an improvement in oxygenation. Milrinone, a selective phosphodiesterase 3 (PDE3) inhibitor with inotropic and lusitropic properties may have potential benefit in PPHN. This pilot study was developed to assess the impact of milrinone administration on time spent on iNO in infants with PPHN. This is a multicentre, randomized, double-blind, two arm pilot study, with a balanced (1:1) allocation of 20 infants. In this pilot study, we hypothesise that infants ≥34 weeks gestation and ≥ 2000 g with a clinical and echocardiography diagnosis of PPHN, intravenous milrinone used in conjunction with iNO will result in a reduction in the time spent on iNO. In addition, we hypothesise that milrinone treatment will lead to an improvement in myocardial performance and global hemodynamics when compared to iNO alone. We will also compare the rate of adverse events associated with the milrinone, and the pre-discharge outcomes of both groups. The purpose of this pilot study is to assess the feasibility of performing the trial and to obtain preliminary data to calculate a sample size for a definitive multi-centre trial of milrinone therapy in PPHN. Trial registration: www.isrctn.com; ISRCTN:12949496; EudraCT Number:2014-002988-16.

An update on the diagnosis and management of bronchopulmonary dysplasia (BPD)-associated pulmonary hypertension

The past decade of neonatal care has been highlighted by increased survival rates in smaller and more premature infants. Despite reduction in mortality associated with extreme prematurity, long term pulmonary morbidities remain a concern, with growing recognition of the clinical burden attributable to infants with bronchopulmonary dysplasia (BPD)-associated pulmonary hypertension (PH). Recent publications shed light on the critical contributions of maternal placental pathology and compromised intrauterine growth to fetal pulmonary vascular development. A body of literature has further clarified postnatal risk factors for PH, most notably the severity of BPD but surprisingly the additional presence of non-pulmonary morbidities including necrotizing enterocolitis (NEC). Limitations of current diagnostics persist with growing consideration of novel echocardiographic approaches as well as complementary non-invasive biomarkers to better identify infants at risk. In 2015, a joint report published by the American Heart Association and American Thoracic Society provided the first guidelines for the care of children with PH with limited content to address BPD-associated PH. These guidelines were expanded upon in an expert consensus report produced by the Pediatric Pulmonary Hypertension Network (PPHNet). These recommendations encouraged the use of standardized screening protocols and emphasized the importance of evaluation and treatment of comorbidities when PH is identified. Cardiac catheterization was recommended prior to initiation of therapy for more accurate quantification of pulmonary pressures, clarification of anatomy and guidance in the use of pharmacotherapy. Despite these guidelines, significant practice variation persists and gaps remain with respect to optimal evaluation and management of BPD-associated PH.

Phosphodiesterase inhibitors: Potential role in the respiratory distress of neonates

Phosphodiesterases (PDEs) are a superfamily of enzymes that catalyze the hydrolysis of phosphodiester bonds of 3',5' cyclic adenosine and guanosine monophosphate (cAMP and cGMP). PDEs control hydrolysis of cyclic nucleotides in many cells and tissues. Inhibition of PDEs by selective or nonselective PDE inhibitors represents an effective targeted strategy for the treatment of various diseases including respiratory disorders. Recent data have demonstrated that PDE inhibitors can also be of benefit in respiratory distress in neonates. This article outlines the pharmacological properties of nonselective and selective PDE inhibitors and provides up-to-date information regarding their use in experimental models of neonatal respiratory distress as well as in clinical studies.

Response to pulmonary vasodilators in infants with congenital diaphragmatic hernia

BACKGROUND

Congenital diaphragmatic hernia (CDH) is associated with lung hypoplasia, cardiac dysfunction and pulmonary hypertension. Inhaled nitric oxide (iNO) and milrinone are commonly used pulmonary vasodilators in CDH. We studied the hemodynamic effects of iNO and milrinone in infants with CDH.

METHODS

A retrospective chart review was performed of all CDH infants admitted to two regional perinatal centers and infants classified into three groups: No-iNO group; iNO-responders and iNO-nonresponders. Oxygenation and hemodynamic effects of iNO and milrinone were assessed by blood gases and echocardiography.

RESULTS

Fifty-four percent (39/72) of infants with CDH received iNO and 31% of these infants (12/39) had complete oxygenation response to iNO. Oxygenation response to iNO was not associated with a decrease in right ventricular pressures (RVP) or ECMO use. Four infants (33%) in the iNO-responder group and eight infants (30%) in the iNO-nonresponder group received milrinone. Milrinone lowered RVP and improved ejection fraction (EF). Response to iNO was associated with improved oxygenation to milrinone and increased survival following ECMO (67 vs. 20% among nonresponders).

CONCLUSIONS

Response to inhaled nitric oxide in combination with milrinone may be associated with improved oxygenation and better survival after ECMO in infants with CDH.

Right ventricular function mirrors clinical improvement with use of prostacyclin analogues in pediatric pulmonary hypertension

Pulmonary hypertension (PH) causes significant morbidity and mortality in children due to right ventricular (RV) failure. We sought to determine the effect of prostacyclin analogues on RV function assessed by echocardiography in children with PH. We conducted a retrospective cohort study of children with PH treated with a prostacyclin analogue (epoprostenol or treprostinil) between January 2001 and August 2015 at our center. Data were collected before initiation of treatment (baseline) and at 1–3 and 6–12 months after. Protocolized echocardiogram measurements including tricuspid annular plane systolic excursion (TAPSE) and RV global longitudinal strain were made with blinding to clinical information. Forty-nine individuals (65% female), aged 0–29 years at the time of prostacyclin initiation were included. Disease types included pulmonary arterial hypertension (idiopathic [35%], heritable [2%], and congenital heart disease-associated [18%]), developmental lung disease (43%), and chronic thromboembolic PH (2%). Participants received intravenous (IV) epoprostenol (14%) and IV/subcutaneous (SQ) (67%) or inhaled (18%) treprostinil. Over the study period, prostacyclin analogues were associated with improvement in TAPSE (P = 0.007), RV strain (P < 0.001), and qualitative RV function (P = 0.037) by echocardiogram, and BNP (P < 0.001), functional class (P = 0.047) and 6-min walk distance (P = 0.001). TAPSE and strain improved at early follow up (P = 0.05 and P = 0.002, respectively) despite minimal RV pressure change. In children with PH, prostacyclin analogues are associated with an early and sustained improvement in RV function measured as TAPSE and strain as well as clinical markers of PH severity. RV strain may be a sensitive marker of RV function in this population.

Beyond the inhaled nitric oxide in persistent pulmonary hypertension of the newborn

Persistent pulmonary hypertension (PPHN) is a consequence of failed pulmonary vascular transition at birth and leads to pulmonary hypertension with shunting of deoxygenated blood across the ductus arteriosus (DA) and foramen ovale (FO) resulting in severe hypoxemia, and it may eventually lead to life-threatening circulatory failure. PPHN is a serious event affecting both term and preterm infants in the neonatal intensive care unit. It is often associated with diseases such as congenital diaphragmatic hernia, meconium aspiration, sepsis, congenital pneumonia, birth asphyxia and respiratory distress syndrome. The diagnosis of PPHN should include echocardiographic evidence of increased pulmonary pressure, with demonstrable right-to-left shunt across the DA or FO, and the absence of cyanotic heart diseases. The mainstay therapy of PPHN includes treatment of underlying causes, maintenance of adequate systemic blood pressure, optimized ventilator support for lung recruitment and alveolar ventilation, and pharmacologic measures to increase pulmonary vasodilation and decrease pulmonary vascular resistance. Inhaled nitric oxide has been proved to treat PPHN successfully with improved oxygenation in 60-70% of patients and to significantly reduce the need for extracorporeal membrane oxygenation (ECMO). About 14%-46% of the survivors develop long-term impairments such as hearing deficits, chronic lung disease, cerebral palsy and other neurodevelopmental disabilities.

Application of Neonatologist Performed Echocardiography in the assessment and management of persistent pulmonary hypertension of the newborn

Pulmonary hypertension contributes to morbidity and mortality in both the term newborn infant, referred to as persistent pulmonary hypertension of the newborn (PPHN), and the premature infant, in the setting of abnormal pulmonary vasculature development and arrested growth. In the term infant, PPHN is characterized by the failure of the physiological postnatal decrease in pulmonary vascular resistance that results in impaired oxygenation, right ventricular failure, and pulmonary-to-systemic shunting. The pulmonary vasculature is either maladapted, maldeveloped, or underdeveloped. In the premature infant, the mechanisms are similar in that the early onset pulmonary hypertension (PH) is due to pulmonary vascular immaturity and its underdevelopment, while late onset PH is due to the maladaptation of the pulmonary circulation that is seen with severe bronchopulmonary dysplasia. This may lead to cor-pulmonale if left undiagnosed and untreated. Neonatologist performed echocardiography (NPE) should be considered in any preterm or term neonate that presents with risk factors suggesting PPHN. In this review, we discuss the risk factors for PPHN in term and preterm infants, the etiologies, and the pathophysiological mechanisms as they relate to growth and development of the pulmonary vasculature. We explore the applications of NPE techniques that aid in the correct diagnostic and pathophysiological assessment of the most common neonatal etiologies of PPHN and provide guidelines for using these techniques to optimize the management of the neonate with PPHN.

Inotropes for Preterm Infants: 50 Years on Are We Any Wiser?

For almost half a century, inotropes have been administered to preterm infants with the ultimate goal of increasing their blood pressure. A number of trials, the majority of which focused on dopamine administration, have demonstrated increased blood pressure following inotrope administration in preterm infants and have led to continued use of inotropes in our neonatal units. We have also seen an increase in the number of potential agents available to the clinician. However, we now know that hypotension is a much broader concept than blood pressure alone, and our aim should instead be focused on improving end organ perfusion, specifically cerebral perfusion. Only a limited number of studies have incorporated the organ-relevant hemodynamic changes and long-term outcomes when assessing inotropic effects in neonates, the majority of which are observational studies or have a small sample size. In addition, important considerations, including the developing/maturing adrenergic receptors, polymorphisms of these receptors, and other differences in the pharmacokinetics and pharmacodynamics of preterm infants, are only recently being recognized. Certainly, there remains huge variation in practice. The lack of well-conducted randomized controlled trials addressing these relevant outcomes, along with the difficulty executing such RCTs, leaves us with more questions than answers. This review provides an overview of the various inotropic agents currently being used in the care of preterm infants, with a particular focus on their organ/cerebral hemodynamic effects both during and after transition.

Cardiovascular Supportive Therapies for Neonates With Asphyxia - A Literature Review of Pre-clinical and Clinical Studies

Asphyxiated neonates often have hypotension, shock, and poor tissue perfusion. Various "inotropic" medications are used to provide cardiovascular support to improve the blood pressure and to treat shock. However, there is incomplete literature on the examination of hemodynamic effects of these medications in asphyxiated neonates, especially in the realm of clinical studies (mostly in late preterm or term populations). Although the extrapolation of findings from animal studies and other clinical populations such as children and adults require caution, it seems appropriate that findings from carefully conducted pre-clinical studies are important in answering some of the fundamental knowledge gaps. Based on a literature search, this review discusses the current available information, from both clinical studies and animal models of neonatal asphyxia, on common medications used to provide hemodynamic support including dopamine, dobutamine, epinephrine, milrinone, norepinephrine, vasopressin, levosimendan, and hydrocortisone.

Deformation imaging and rotational mechanics in neonates: a guide to image acquisition, measurement, interpretation, and reference values

Advances in neonatal cardiac imaging permit a more comprehensive assessment of myocardial performance in neonates that could not be previously obtained with conventional imaging. Myocardial deformation analysis is an emerging quantitative echocardiographic technique to characterize global and regional ventricular function in neonates. Cardiac strain is a measure of tissue deformation and strain rate is the rate at which deformation occurs. These measurements are obtained in neonates using tissue Doppler imaging (TDI) or two-dimensional speckle tracking echocardiography (STE). There is an expanding body of literature describing longitudinal reference ranges and maturational patterns of strain values in term and preterm infants. A thorough understanding of deformation principles, the technical aspects, and clinical applicability is a prerequisite for its routine clinical use in neonates. This review explains the fundamental concepts of deformation imaging in the term and preterm population, describes in a comparative manner the two major deformation imaging methods, provides a practical guide to the acquisition and interpretation of data, and discusses their recognized and developing clinical applications in neonates.

Milrinone in congenital diaphragmatic hernia - a randomized pilot trial: study protocol, review of literature and survey of current practices

Background

Congenital diaphragmatic hernia (CDH) is commonly associated with pulmonary hypoplasia and pulmonary hypertension (PH). PH associated with CDH (CDH-PH) is frequently resistant to conventional pulmonary vasodilator therapy including inhaled nitric oxide (iNO) possibly due to right and left ventricular dysfunction. Milrinone is an intravenous inotrope and lusitrope with pulmonary vasodilator properties and has been shown anecdotally to improve oxygenation in PH. We developed this pilot study to determine if milrinone infusion would improve oxygenation in neonates ≥36 weeks postmenstrual age (PMA) with CDH.

Methods/design

Data on pulmonary vasodilator management and outcome of CDH patients was collected from 18 university NICUs affiliated with the Neonatal Research Network (NRN) from 2011 to 2012. The proposed pilot will be a masked, placebo–controlled, multicenter, randomized trial of 66 infants with CDH with an oxygenation index (OI) ≥10 or oxygen saturation index (OSI) ≥5. The primary outcome is the oxygenation response, as determined by change in OI at 24 h after initiation of study drug. As secondary outcomes, we will determine oxygenation at 48 h and 72 h post-infusion, right ventricular pressures on echocardiogram and the incidence of systemic hypotension, arrhythmias, intracranial hemorrhage, survival without extracorporeal membrane oxygenation, and chronic lung disease (oxygen need at 28 days postnatal age). Finally, we will evaluate the pulmonary and nutritional status at 4, 8 and 12 months of age using a phone questionnaire.

Results

Three hundred thirty-seven infants with CDH were admitted to NRN NICUs in 2011 and 2012 of which 275 were ≥36 weeks PMA and were exposed to the following pulmonary vasodilators: iNO (39%), sildenafil (17%), milrinone (17%), inhaled epoprostenol (6%), intravenous epoprostenol (3%), and intravenous PGE1 (1%). ECMO was required in 36% of patients. Survival to discharge was 71%.

Discussion

CDH is an orphan disease with high mortality with few randomized trials evaluating postnatal management. Intravenous milrinone is a commonly used medication in neonatal/pediatric intensive care units and is currently used in 17% of patients with CDH within the NRN. This pilot study will provide data and enable further studies evaluating pulmonary vasodilator therapy in CDH.

Trial registration

ClinicalTrials.gov; NCT02951130; registered 14 October 2016.

Right heart dysfunction and failure in heart failure with preserved ejection fraction: mechanisms and management. Position statement on behalf of the Heart Failure Association of the European Society of Cardiology

There is an unmet need for effective treatment strategies to reduce morbidity and mortality in patients with heart failure with preserved ejection fraction (HFpEF). Until recently, attention in patients with HFpEF was almost exclusively focused on the left side. However, it is now increasingly recognized that right heart dysfunction is common and contributes importantly to poor prognosis in HFpEF. More insights into the development of right heart dysfunction in HFpEF may aid to our knowledge about this complex disease and may eventually lead to better treatments to improve outcomes in these patients. In this position paper from the Heart Failure Association of the European Society of Cardiology, the Committee on Heart Failure with Preserved Ejection Fraction reviews the prevalence, diagnosis, and pathophysiology of right heart dysfunction and failure in patients with HFpEF. Finally, potential treatment strategies, important knowledge gaps and future directions regarding the right side in HFpEF are discussed.

Hemodynamic Assessment and Monitoring of Premature Infants

The management of the hemodynamic status of critically ill preterm infants, particularly around the periviable period, remains a significant challenge in the neonatal intensive care unit for a multitude of reasons. The causes of hemodynamic compromise in this population are heterogeneous and usually superimposed on the complex physiologic processes that occur during transition from fetal to neonatal life. This review outlines the unique nature of low blood flow states in this population and present an overview of the current methods for identification and assessment of hemodynamic compromise.

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

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

A new look at bronchopulmonary dysplasia: postcapillary pathophysiology and cardiac dysfunction

Pulmonary hypertension (PH) and right ventricular function are the focus of cardiovascular effects of bronchopulmonary dysplasia (BPD). We assessed cardiac indexes reflecting systemic afterload and pulmonary venous back pressure as pathophysiologic factors. Cardiac parameters were measured by conventional echocardiography in 20 preterm infants with severe BPD and compared with those of 10 preterm infants with no BPD and 20 healthy term infants. In infants with severe BPD, PH was noted in 5 (25%) by tricuspid regurgitation Doppler jet ≥2.8 m/s and in 15 (75%) by time to peak velocity/right ventricular ejection time <0.34. Among systemic cardiac indexes, significant impairment of diastolic measures was noted in the BPD group compared with infants with no BPD and term infants. The significance persisted after adjusting for gestational age and birth weight. These included transmitral E/A ratio (1.07 ± 0.07 vs. 0.91 ± 0.04 vs. 0.89 ± 0.09; P < 0.0001), isovolumic relaxation time (68.8 ± 3.9 vs. 58.5 ± 7.8 vs. 54.2 ± 5.7 ms ; P < 0.0001), mitral valve stroke volume (4.7 ± 0.7 vs. 5.6 ± 0.6 vs. 5.9 ± 0.1; P = 0.002), and myocardial performance index (0.33 ± 0.05 vs. 0.28 ± 0.01 vs. 0.27 ± 0.05; P = 0.03). Left ventricular output was significantly lower in the BPD cohort (183 ± 45 vs. 189 ± 9 vs. 191 ± 32 mL/kg/min; P = 0.03). Altered systemic (left-sided) cardiac function was noted in infants with BPD, which may lead to pulmonary venous congestion contributing to a continued need for respiratory support.

PDE3 inhibition with enoximone as first-line therapy for severe persistent pulmonary hypertension of the newborn during neonatal transport: a case report

Severe Persistent pulmonary hypertension of the newborn (PPHN) can be effectively treated with a PDE3 inhibitor as first‐line treatment during neonatal transport when iNO is not readily available. Starting iNO as soon as possible is strongly advised because of the complementary actions of both therapeutics.

Pharmacologic strategies in neonatal pulmonary hypertension other than nitric oxide

Inhaled nitric oxide (iNO) is approved for use in persistent pulmonary hypertension of the newborn (PPHN) but does not lead to sustained improvement in oxygenation in one-third of patients with PPHN. Inhaled NO is less effective in the management of PPHN secondary to congenital diaphragmatic hernia (CDH), extreme prematurity, and bronchopulmonary dysplasia (BPD). Intravenous pulmonary vasodilators such as prostacyclin, alprostadil, sildenafil, and milrinone have been successfully used in PPHN resistant to iNO. Oral pulmonary vasodilators such as endothelin receptor antagonist bosentan and phosphodiesterase-5 inhibitors such as sildenafil and tadalafil are used both during acute and chronic phases of PPHN. In the absence of infection, glucocorticoids may also be effective in PPHN. Many of these pharmacologic agents are not approved for use in PPHN and our knowledge is based on case reports and small trials. Large multicenter randomized controlled trials with long-term follow-up are required to evaluate alternate pharmacologic strategies in PPHN.

Advances in Neonatal Pulmonary Hypertension

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

Persistent pulmonary hypertension of the newborn

Persistent pulmonary hypertension of the newborn (PPHN) is characterized by elevated pulmonary vascular resistance resulting in right-to-left shunting of blood and hypoxemia. PPHN is often secondary to parenchymal lung disease (such as meconium aspiration syndrome, pneumonia or respiratory distress syndrome) or lung hypoplasia (with congenital diaphragmatic hernia or oligohydramnios) but can also be idiopathic. The diagnosis of PPHN is based on clinical evidence of labile hypoxemia often associated with differential cyanosis. The diagnosis is confirmed by the echocardiographic demonstration of - (a) right-to-left or bidirectional shunt at the ductus or foramen ovale and/or, (b) flattening or leftward deviation of the interventricular septum and/or, (c) tricuspid regurgitation, and finally (d) absence of structural heart disease. Management strategies include optimal oxygenation, avoiding respiratory and metabolic acidosis, blood pressure stabilization, sedation and pulmonary vasodilator therapy. Failure of these measures would lead to consideration of extracorporeal membrane oxygenation (ECMO); however decreased need for this rescue therapy has been documented with advances in medical management. While trends also note improved survival, long-term neurodevelopmental disabilities such as deafness and learning disabilities remain a concern in many infants with severe PPHN. Funded by: 1R01HD072929-0 (SL).