Physiological-based cord clamping versus immediate cord clamping for infants born with a congenital diaphragmatic hernia (PinC): study protocol for a multicentre, randomised controlled trial

Multicentre, randomised controlled trial of physiological-based cord clamping versus immediate cord clamping in infants with a congenital diaphragmatic hernia (PinC): statistical analysis plan

BACKGROUND

Infants born with congenital diaphragmatic hernia (CDH) are at high risk of respiratory insufficiency and pulmonary hypertension. Routine practice includes immediate clamping of the umbilical cord and endotracheal intubation. Experimental animal studies suggest that clamping the umbilical cord guided by physiological changes and after the lungs have been aerated, named physiological-based cord clamping (PBCC), could enhance the fetal-to-neonatal transition in CDH. We describe the statistical analysis plan for the clinical trial evaluating the effects of PBCC versus immediate cord clamping on pulmonary hypertension in infants with CDH (PinC trial).

DESIGN

The PinC trial is a multicentre, randomised controlled trial in infants with isolated left-sided CDH, born ≥ 35.0 weeks of gestation. The primary outcome is the incidence of pulmonary hypertension in the first 24 h after birth. Maternal outcomes include estimated maternal blood loss. Neonatal secondary outcomes include mortality before discharge, extracorporeal membrane oxygenation therapy, and number of days of mechanical ventilation. Infants are 1:1 randomised to either PBCC or immediate cord clamping using variable random permutated block sizes (4-8), stratified by treatment centre and estimated severity of pulmonary hypoplasia (i.e. mild/moderate/severe). At least 140 infants are needed to detect a relative reduction in pulmonary hypertension by one third, with 80% power and 0.05 significance level. A chi-square test will be used to evaluate the hypothesis that PBCC decreases the occurrence of pulmonary hypertension. This plan is written and submitted without knowledge of the collected data. The trial has been ethically approved.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04373902 (registered April 2020).

Recent advances in the treatment of complex congenital diaphragmatic hernia-a narrative review

Background and Objective

Congenital diaphragmatic hernia (CDH) is an anomaly of the cardiopulmonary system maturation process that results from both a global embryopathy and concomitant mechanical compression of the cardiopulmonary system from the abdominal contents during fetal maturation. This results in pulmonary hypertension, pulmonary hypoplasia, and cardiac dysfunction, requiring intense critical care management. The patients with highest risk CDH are the most challenging, resource-intensive, and bear most of the mortality. Advances at the basic, translational, and clinical research levels are leading to novel therapies and management strategies for complex, high-risk CDH. Our objective is to review novel approaches in thinking and management for the most complex and high-risk CDH patients. These include patients with prenatal and postnatal indicators of high-risk defects, those receiving extracorporeal life support (ECLS), and those with concomitant anomalies such as complex cardiac and/or chromosomal abnormalities.

Methods

PubMed was searched in late 2022 and early 2023 to identify relevant evidence. Search terms included congenital diaphragmatic hernia (CDH)", "extracorporeal life support (ECLS)", "pulmonary hypertension", "dual-hit hypothesis", "risk reduction", "cardiac/chromosomal anomalies", and "novel therapies". We included trials, multicenter studies (prospective and retrospective), single-center reports, and review articles/expert opinion.

Key Content and Findings

CDH is a congenital anomaly of the cardiopulmonary and diaphragmatic systems that represents a spectrum of disease. High-risk or complex patients are defined by prenatal/postnatal risk stratification, receipt of ECLS, and/or having concomitant anomalies, representing the severe end of that spectrum. Overall survival of high-risk CDH is about 50% and comprises the vast majority of mortality, mandating special emphasis. The development of risk-stratification processes, best practices or guidelines of management, and novel therapies is critical to optimize the care of these infants.

Conclusions

CDH patients with high-risk disease remain a challenging subset of CDH patients. Increasing opportunities for survival are being realized with novel, investigational approaches.

The Association between the First Cry and Clinical Outcomes in CDH Neonates: A Retrospective Study

Congenital diaphragmatic hernia (CDH) is a life-threatening condition characterized by the herniation of abdominal organs into the thorax, resulting in hypoplastic lungs and pulmonary hypertension. The impact of the first cry, a crucial event for lung transition during birth, on CDH patients remains unclear. This study investigated the impact of the first cry during birth on CDH patient survival, along with other prognosis factors. A multi-institutional retrospective study assessed CDH patient characteristics and survival rates by analyzing factors including the first cry, disease severity, birth weight, Apgar scores, oxygenation index (OI) and surgical closure. Among the CDH patients in the study, a positive first cry was linked to 100% survival, regardless of disease severity (p < 0.001). Notably, the presence of a positive first cry did not significantly affect survival rates in patients with worse prognostic factors, such as low birth weight (<2500 g), high CDH severity, low Apgar scores (1 min ≤ 4), high best OI within 24 h after birth (≥8), or those who underwent patch closure. Furthermore, no significant association was found between the first cry and the use of inhaled nitric oxide (iNO) or extracorporeal membrane oxygenation (ECMO). In conclusion, this study suggests that the first cry may not have a negative impact on the prognosis of CDH patients and could potentially have a positive effect.

Assisted ventilation prior to umbilical cord clamping: Potential benefits, challenges, and research studies

Delayed cord clamping (DCC) is beneficial for many infants, and the American College of Obstetrics and Gynecology recommends at least 30-60 seconds of DCC for both term and preterm vigorous infants. For newly born infants that are not vigorous, some evidence in animal models suggests that providing assisted ventilation prior to cord clamping (V-DCC) leads to a more stable transition of cerebral, pulmonary and systemic circulation and oxygenation and may confer not only short-term physiologic benefits but perhaps also improvement in clinically important outcomes. This review is based around 7 questions to help the reader understand the physiologic underpinnings and challenges of V-DCC as well as the published and ongoing research studies aimed at determining whether V-DCC is beneficial for preterm or term infants.

Sedation Prior to Intubation at Birth in Infants with Congenital Diaphragmatic Hernia: An International Survey on Current Practices

INTRODUCTION

Infants with congenital diaphragmatic hernia (CDH) are commonly intubated immediately after birth. Consensus on whether to provide sedation prior to intubation in the delivery room is lacking, although avoidance of stress is especially important in this population with high risk of pulmonary hypertension. We aimed at obtaining an overview of local pharmacological interventions and at providing guidance on delivery room management.

METHODS

An electronic survey was sent to international clinicians in referral centres for prenatal and postnatally diagnosed infants with CDH. This survey addressed demographic information, use of sedation and/or muscle relaxant prior to intubation, and use of pain scales in the delivery room.

RESULTS

We received 93 relevant responses from 59 centres. Most centres were from Europe (n = 33, 56%), followed by North America (n = 16, 27%), Asia (n = 6, 10%), Australia (n = 2, 3%), and South America (n = 2, 3%). A total of 19% (11/59) of the centres routinely provided sedation prior to intubation in the delivery room, with midazolam and fentanyl being most often used. Methods of administration varied for all medications provided. Only 5 of 11 centres using sedation reported an adequate sedative effect prior to intubation. Muscle relaxants prior to intubation were used in 12% (7/59) of the centres, although not always in combination with sedation.

CONCLUSION

This international survey shows a substantial variation in sedation practices in the delivery room and scarce use of both sedative agents and muscle relaxants prior to intubation of CDH infants. We provide guidance on developing protocols for pre-intubation medication in this population.

Timing of umbilical cord clamping in infants with congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a severe birth anomaly where a defect in the diaphragm allows abdominal organs to herniate into the chest with compression of the intrathoracic structures, specifically the lungs and heart. Pulmonary and left ventricular hypoplasia result in respiratory insufficiency after birth with disordered transition and persistent pulmonary hypertension of the newborn (PPHN). As a result, infants need immediate intervention after birth to support the transition. Delayed cord clamping (DCC) is recommended for all healthy newborns and improves outcomes in infants born preterm and in infants with congenital heart disease; however, DCC may not be feasible in newborns needing immediate intervention after birth. Recent studies have explored resuscitation with intact umbilical cords, to determine feasibility, safety, and efficacy in infants with CDH, with promising results. In this report we discuss the physiologic basis for intact cord resuscitation in infants with CDH and review the above reports with a view to determining optimal timing of umbilical cord clamping in infants with CDH.

Maternal implications of placental transfusion

Placental transfusion for 30-60 s after delivery is recommended by numerous professional societies and is now a common practice. Numerous studies document neonatal benefit with minimal maternal risk when routine neonatal stabilization and active management of the third stage of labor are undertaken during the period of delayed cord clamping. Maternal outcomes do not show any increased incidence of postpartum hemorrhage, or need for blood product transfusion in the case of vaginal delivery or cesarean section. Fetomaternal hemorrhage is also likely decreased with delayed cord clamping. In the case of fetal anomalies, cord management should be individualized according to each special circumstance, but is unlikely to lead to increased maternal morbidity. While few studies have investigated maternal outcomes with umbilical cord milking, this practice has not been as widely adopted. With careful monitoring of maternal and fetal well-being, a period of placental transfusion following delivery is advised for benefit of the neonate without significant maternal risk.

The heart in congenital diaphragmatic hernia: Knowns, unknowns, and future priorities

There is growing recognition that the heart is a key contributor to the pathophysiology of congenital diaphragmatic hernia (CDH), in conjunction with developmental abnormalities of the lung and pulmonary vasculature. Investigations to date have demonstrated altered fetal cardiac morphology, notably relative hypoplasia of the fetal left heart, as well as early postnatal right and left ventricular dysfunction which appears to be independently associated with adverse outcomes. However, many more unknowns remain, not least an understanding of the genetic and cellular basis for cardiac dysplasia and dysfunction in CDH, the relationship between fetal, postnatal and long-term cardiac function, and the impact on other parts of the body especially the developing brain. Consensus on how to measure and classify cardiac function and pulmonary hypertension in CDH is also required, potentially using both non-invasive imaging and biomarkers. This may allow routine assessment of the relative contribution of cardiac dysfunction to individual patient pathophysiological phenotype and enable better, individualized therapeutic strategies incorporating targeted use of fetal therapies, cardiac pharmacotherapies, and extra-corporeal membrane oxygenation (ECMO). Collaborative, multi-model approaches are now required to explore these unknowns and fully appreciate the role of the heart in CDH.