Hemodynamic consequences of respiratory interventions in preterm infants

Cardiac Development and Related Clinical Considerations

The anatomy, physiology, and hemodynamics of the premature heart vary along the range of gestational ages cared for in neonatal intensive care units, from 22 weeks to term gestation. Clinical management of the preterm neonate should account for this heterogenous development. This requires an understanding of the impact of ex utero stressors on immature and disorganized cardiac tissue, the different state of hemodynamics across intracardiac shunts impacting the natural transition from fetal to neonatal life, and the effects of intensive pharmacologic and non-pharmacologic interventions that have systemic consequences influencing cardiac function. This article provides a review of the increasing but still limited body of literature on the anatomy, hemodynamics, and electrophysiology of the preterm heart with relevant clinical considerations.

Navigating Diagnostic and Treatment Challenges of Pulmonary Hypertension in Infants with Bronchopulmonary Dysplasia

Advances in perinatal intensive care have significantly enhanced the survival rates of extremely low gestation-al-age neonates but with continued high rates of bronchopulmonary dysplasia (BPD). Nevertheless, as the survival of these infants improves, there is a growing awareness of associated abnormalities in pulmonary vascular development and hemodynamics within the pulmonary circulation. Premature infants, now born as early as 22 weeks, face heightened risks of adverse development in both pulmonary arterial and venous systems. This risk is compounded by parenchymal and airway abnormalities, as well as factors such as inflammation, fibrosis, and adverse growth trajectory. The presence of pulmonary hypertension in bronchopulmonary dysplasia (BPD-PH) has been linked to an increased mortality and substantial morbidities, including a greater susceptibility to later neurodevelopmental challenges. BPD-PH is now recognized to be a spectrum of disease, with a multifactorial pathophysiology. This review discusses the challenges associated with the identification and management of BPD-PH, both of which are important in minimizing further disease progression and improving cardiopulmonary morbidity in the BPD infant.

Impact of Early Surfactant Administration on Ductus Arteriosus Assessed at 24 h in Preterm Neonates Less than 32 Weeks of Gestational Age

BACKGROUND AND OBJECTIVES

The purpose of this study was to investigate whether early surfactant administration affects the status of ductus arteriosus (DA) in preterm infants ≤ 32 weeks of gestational age (GA) within 24 h of birth.

MATERIALS AND METHODS

It is a prospective study conducted from 1 March 2022 to 31 December 2023 in a tertiary academic center. In-born infants ≤ 32 weeks of gestation (n = 88) were enrolled. The study group was further divided into surfactant (n = 44) and non-surfactant (n = 44) subgroups.

RESULTS

A total of 76% of the preterm infants who received surfactant therapy (RRR = 0.839) recorded an increase in Kindler score at 24 h of life (1 - RR = 1 - 0.24 = 76%). Surfactant administration was significantly associated with decreased pre-ductal diastolic pressure (29.9 mmHg vs. 34.8 mmHg, p = 0.0231), post-ductal diastolic pressure (28.7 mmHg vs. 32.2 mmHg, p = 0.0178), pre-ductal MAP (41.6 mmHg vs. 46.5 mmHg, p = 0.0210), and post-ductal MAP (41.0 mmHg vs. 45.3 mmHg, p = 0.0336). There were no significant changes in ductus arteriosus parameters at 24 h of life.

CONCLUSIONS

Early surfactant administration does not affect the status of ductus arteriosus in preterm infants ≤ 32 weeks of gestational age at 24 h of life.

Ductus Arteriosus in Fetal and Perinatal Life

The ductus arteriosus represents an essential vascular structure connecting the pulmonary artery and the aorta. Over the past decades, there has been substantial advancement in our understanding of both the fundamental and clinical aspects of the ductus arteriosus. In particular, the clarification of the regulatory mechanisms governing ductal patency in critical stages such as the fetal and the perinatal period has enabled optimal management of both physiological and pathological conditions in which the ductus arteriosus plays a crucial role. Furthermore, a more in-depth understanding of the regulatory mechanisms controlling this fundamental structure has facilitated the development of advanced therapeutic strategies and personalized interventions. In the present review, we provide a comprehensive overview of the ductus arteriosus during fetal and perinatal life, encompassing its physiological functions, pathological conditions, and clinical implications. Through this examination, we aim to contribute to a broader understanding of the ductus arteriosus' role in these critical developmental stages and its significance in clinical practice.

Spontaneous breathing in selected neonates with very mild congenital diaphragmatic hernia

AIMS

Current treatment guidelines recommend immediate postnatal intubation in all neonates with congenital diaphragmatic hernia (CDH). This study aimed to investigate the feasibility and outcomes of a spontaneous breathing approach (SBA) versus immediate intubation in neonates with prenatally diagnosed very mild CDH.

METHODS

A retrospective study was conducted comparing neonates with very mild CDH (left-sided, liver-down, observed-to-expected lung-to-head ratio ≥45%) undergoing SBA and matched controls receiving standard treatment. Data on early echocardiographic findings, respiratory support, length of hospital stay, and clinical outcomes were analyzed.

RESULTS

Of 151 CDH neonates, eight underwent SBA, while 31 received standard treatment. SBA was successful in six of eight patients. SBA patients had shorter length of stay (14 vs. 30 days, p = .005), mechanical ventilation (3.5 vs. 8.7 days, p = .011), and oxygen supplementation (3.2 vs. 9.3 days, p = .013) compared to matched controls. Echocardiographic evidence of pulmonary hypertension and cardiac dysfunction were significantly lower in SBA neonates after admission but similar before surgical repair. The SBA group tolerated enteral feeding earlier (day of life 7 vs. 16, p = .019).

CONCLUSIONS

SBA appears feasible and beneficial for prenatally diagnosed very mild CDH. It was associated with a shortened hospital stay supportive therapies. However, larger trials are needed to confirm these findings and determine optimal respiratory support.

Transferring an extremely premature infant to an extra-uterine life support system: a prospective view on the obstetric procedure

To improve care for extremely premature infants, the development of an extrauterine environment for newborn development is being researched, known as Artificial Placenta and Artificial Womb (APAW) technology. APAW facilitates extended development in a liquid-filled incubator with oxygen and nutrient supply through an oxygenator connected to the umbilical vessels. This setup is intended to provide the optimal environment for further development, allowing further lung maturation by delaying gas exposure to oxygen. This innovative treatment necessitates interventions in obstetric procedures to transfer an infant from the native to an artificial womb, while preventing fetal-to-neonatal transition. In this narrative review we analyze relevant fetal physiology literature, provide an overview of insights from APAW studies, and identify considerations for the obstetric procedure from the native uterus to an APAW system. Lastly, this review provides suggestions to improve sterility, fetal and maternal well-being, and the prevention of neonatal transition.

Surfactant and neonatal hemodynamics during the postnatal transition

Surfactant replacement therapy (SRT) has revolutionized the management of respiratory distress syndrome (RDS) in premature infants, leading to improved survival rates and decreased morbidity. SRT may, however, be associated with hemodynamic changes, which can have both positive and negative effects on the immature cardiovascular system, during the transitional adaptation from fetal to extrauterine environment. However, there is a relative paucity of evidence in this domain, with most of them derived from small heterogeneous observational studies providing conflicting results. In this review, we will discuss the hemodynamic changes that occur with surfactant administration during this vulnerable period, focusing on available evidence regarding changes in pulmonary and systemic blood flow, cerebral circulation and their clinical implications.

The association between patterns of early respiratory disease and diastolic dysfunction in preterm infants

BACKGROUND

This study aims to determine the association between clinical patterns of early respiratory disease and diastolic dysfunction in preterm infants.

METHODS

Preterm infants <29 weeks' gestation underwent cardiac ultrasounds around day 7 and 14-21. Respiratory dysfunction patterns were classified as stable (ST), respiratory deterioration (RD) or early persistent respiratory dysfunction (EPRD) according to oxygen need. Diastolic dysfunction was diagnosed using a multi-parameter approach including left atrial strain (LASR) to help differentiate between cardiac or pulmonary pathophysiology.

RESULTS

98 infants (mean 27 weeks) were included. The prevalence of ST, RD and EPRD was 53%, 21% and 26% respectively. Diastolic dysfunction was more prevalent in the RD and EPRD groups with patent ductus arteriosus and significant growth restriction as risk factors. Not all infants with a PDA developed diastolic dysfunction. LASR was lower in the EPDR group.

CONCLUSION

Respiratory dysfunction patterns are associated with diastolic dysfunction in preterm infants.

The left ventricle in well newborns versus those with perinatal asphyxia, haemodynamically significant ductus arteriosus or fetal growth restriction

Hemodynamic changes accompanying the initial breaths at the time of birth are especially important for a smooth transition of fetal to neonatal circulation. Understanding the normal transitional physiology and the clinical impact of adverse adaptation is important for delineating pathology so as to guide physiologically relevant therapies. Disorders such as severe perinatal asphyxia, hemodynamically significant patent ductus arteriosus (and its surgical ligation) and utero-placental insufficiency underlying fetal growth restriction, can adversely affect left ventricular (LV) function. The left ventricle is the predominant chamber involved in systemic perfusion during postnatal life. Cardiac output is closely linked to afterload; the latter is determined by arterial properties such as stiffness and compliance. This article outlines normal transition in term and preterm infants. It also highlights the adverse impact of three not uncommon neonatal disorders on LV function. Perinatal asphyxia leads to a reduced LV output, superior vena cava and coronary artery blood flow and an increase in the troponin level. Multiple haemodynamic changes are observed in the premature infant with a large patent ductus arteriosus. They need careful analysis to determine when ligation should proceed. Ligation itself generally results in a dramatic increase in afterload which may lead to a reduction in LV contractility and the need for ionotropic support. Fetal growth restricted infants have a higher systolic pressure, a somewhat hypertrophied heart arising from an increased arterial wall thickness/stiffness and systemic peripheral resistance. Point of care ultrasound (POCUS) helps differentiate normal transition and that resulting from neonatal disorders. It may be increasingly utilized in guiding management.