Early use of combined exogenous surfactant and inhaled nitric oxide reduces treatment failure in persistent pulmonary hypertension of the newborn: a randomized controlled trial

Risk Factors and Mortality in Newborns with Persistent Pulmonary Hypertension: A Six-Year Single-Center Experience

Objectives

Persistent pulmonary hypertension (PPHT) of the newborn is a disorder of circulatory transition resulting in high pulmonary vascular resistance with extrapulmonary right-to-left shunts causing hypoxemia. In this study, our aim was to evaluate the risk factors, administered treatments, and mortality of patients followed in our neonatal intensive care unit (NICU) due to PPHT over the past six years.

Methods

Patients diagnosed with PPHT and followed in the NICU between January 2017 and November 2022 were included in the study. The sociodemographic characteristics, diagnoses that could lead to pulmonary hypertension, the presence of congenital anomalies, the duration of respiratory support treatment and hospital follow-up, treatments administered for PPHT, and mortality rates were evaluated.

Results

Out of 21 patients diagnosed with persistent pulmonary hypertension, 9 of them (42.9%) were male. The mean gestational age of the patients was 37.6±3.7 weeks, and their birth weight was 3006±819grams. The APGAR scores at 1 and 5 minutes were 4(2-7) and 6(3-8), respectively. Risk factors during the antenatal period included fetal distress (38.1%), oligohydramnios (23.8%), intrauterine growth restriction (23.8%), gestational diabetes (14.3%), preeclampsia (4.8%), and chorioamnionitis (4.8%). The median duration of invasive mechanical ventilation for cases requiring respiratory support was 20.1 days, while the median duration of non-invasive ventilation was 3.7 days. Patients with a diagnosis of persistent pulmonary hypertension were treated with inhaled nitric oxide (iNO) in 76.2% of cases, milrinone in 66.7% of cases, sildenafil in 52.4% of cases, and iloprost in 14.3% of cases. The length of hospital stay for patients was 38.4 days, and 9 (42.9%) patients died. The patients who died had severe PPHT along with fetal inflammatory response syndrome (FIRS), congenital heart disease, pulmonary hypoplasia, pneumothorax, hypoxic-ischemic encephalopathy (HIE), and congenital anomalies.

Conclusion

Persistent pulmonary hypertension, characterized by severe hypoxemia, is a neonatal emergency that necessitates early intervention, effective treatment of the underlying cause to prevent potential short-term and long-term morbidities and mortality. Effective treatment of the underlying cause in patients diagnosed with PPHT could reduce morbidity and mortality. It is inevitable to avoid the loss of patients with major abnormalities, severe comorbidities, and unpreventable organ dysfunctions.

Use of surfactant beyond respiratory distress syndrome, what is the evidence?

Surfactant replacement therapy is currently approved by the United States Food and Drug Administration (FDA) for premature infants with respiratory distress syndrome (RDS) caused by surfactant deficiency due to immaturity. There is strong evidence that surfactant decreases mortality and air leak syndromes in premature infants with RDS. However, surfactant is also used "off-label" for respiratory failure beyond classic RDS. This review discusses current evidence for the use of off-label surfactant therapy for (1) term infants with lung disease such as meconium aspiration syndrome (MAS), pneumonia/sepsis, and congenital diaphragmatic hernia (2) premature infants after 72 h for acute respiratory failure, and (3) the use of surfactant lavage. At last, we briefly describe the use of surfactants for drug delivery and the current evidence on evaluating infants for surfactant deficiency.

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.

Novel scoring tool of hypoxemic respiratory failure and pulmonary hypertension for defining severity of persistent pulmonary hypertension of newborn

OBJECTIVE

To obtain preliminary validity data for a hypoxemic respiratory failure/pulmonary hypertension (HRF/PH) score for classifying persistent pulmonary hypertension of the newborn (PPHN).

STUDY DESIGN

Retrospective chart review of 100 consecutive neonates admitted to a Children's hospital from 2016-2021 with PPHN, gestational age ≥34 weeks, and echocardiograms in the first week. We assessed the correlation between HRF/PH score and short-term outcomes using linear and logistic regressions.

RESULTS

HRF/PH scores ranged 2-12 (mean 8.5), and were classified mild (0-5), moderate (6-10), and severe (11-15), with 6%, 77% and 17% infants in respective categories. HRF/PH score category correlated with invasive ventilation, nitric oxide, high frequency ventilation, vasoactive infusions, extracorporeal life support and death. HRF/PH score category did not correlate with duration of support or length of stay.

CONCLUSION

The HRF/PH score offers a promising representation of disease severity for PPHN. The tool requires further validation in prospective studies and evaluation for long-term outcomes.

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.

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.

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.

Association of Adherence to Surfactant Best Practice Uses With Clinical Outcomes Among Neonates in Sweden

IMPORTANCE

While surfactant therapy for respiratory distress syndrome (RDS) in preterm infants has been evaluated in clinical trials, less is known about how surfactant is used outside such a framework.

OBJECTIVE

To evaluate registered use, off-label use, and omissions of surfactant treatment by gestational age (GA) and associations with outcomes, mainly among very preterm infants (GA <32 weeks).

DESIGN, SETTING, AND PARTICIPANTS

This population-based cohort study used registry data for 97 377 infants born in Sweden between 2009 and 2018. Infants did not have malformations and were admitted for neonatal care. Data analysis was conducted from June 2019 to June 2020.

EXPOSURES

Timing and number of surfactant administrations, off-label use, and omission of use. Registered use was defined by drug label (1-3 administrations for RDS). Omissions were defined as surfactant not administered despite mechanical ventilation for RDS.

MAIN OUTCOME AND MEASURES

In-hospital survival, pneumothorax, intraventricular hemorrhage grade 3 to 4, duration of mechanical ventilation, use of postnatal systemic corticosteroids for lung disease, treatment with supplemental oxygen at 28 days' postnatal age and at 36 weeks' postmenstrual age. Odds ratios (ORs) were calculated and adjusted for any prenatal corticosteroid treatment, cesarean delivery, GA, infant sex, Apgar score at 10 minutes, and birth weight z score of less than -2.

RESULTS

In total, 7980 surfactant administrations were given to 5209 infants (2233 [42.9%] girls; 2976 [57.1%] boys): 629 (12.1%) born at full term, 691 (13.3%) at 32 to 36 weeks' GA, 1544 (29.6%) at 28 to 31 weeks' GA, and 2345 (45.0%) at less than 28 weeks' GA. Overall, 977 infants (18.8%) received off-label use. In 1364 of 3508 infants (38.9%) with GA of 22 to 31 weeks, the first administration of surfactant was given more than 2 hours after birth, and this was associated with higher odds of pneumothorax (adjusted OR [aOR], 2.59; 95% CI, 1.76-3.83), intraventricular hemorrhage grades 3 to 4 (aOR, 1.71; 95% CI, 1.23-2.39), receipt of postnatal corticosteroids (aOR, 1.57; 95% CI, 1.22-2.03), and longer duration of assisted ventilation (aOR, 1.34; 95% CI, 1.04-1.72) but also higher survival (aOR, 1.45; 95% CI, 1.10-1.91) than among infants treated within 2 hours of birth. In 146 infants (2.8%), the recommended maximum of 3 surfactant administrations was exceeded but without associated improvements in outcome. Omission of surfactant treatment occurred in 203 of 3551 infants (5.7%) who were receiving mechanical ventilation and was associated with lower survival (aOR, 0.49; 95% CI, 0.30-0.82). In full-term infants, 336 (53.4%) of those receiving surfactant had a diagnosis of meconium aspiration syndrome. Surfactant for meconium aspiration was not associated with improved neonatal outcomes.

CONCLUSIONS AND RELEVANCE

In this study, adherence to best practices and labels for surfactant use in newborn infants varied, with important clinical implications for neonatal outcomes.

Surf early to higher tides: surfactant therapy to optimize tidal volume, lung recruitment, and iNO response

Inhaled nitric oxide is approved by FDA for the management of hypoxemic respiratory failure in term and near-term infants. However, approximately a third of patients treated with inhaled nitric oxide fail to have a sustained improvement in oxygenation. Recruitment of the lung with surfactant enables optimal delivery of nitric oxide to the alveolar space leading to effective pulmonary vasodilation.