Pulmonary barotrauma in congenital diaphragmatic hernia: a clinicopathological correlation

Comparison of Clinical Endotracheal Tube Depths with Standard Estimates for the Stabilization of Infants with Congenital Diaphragmatic Hernia

OBJECTIVE

 This study aimed to compare the clinical endotracheal tube (ETT) depth after initial stabilization of infants with congenital diaphragmatic hernia (CDH) to weight and gestational age-based depth estimates.

STUDY DESIGN

 This retrospective analysis included 58 inborn infants with left-sided CDH. We compared a standard anatomic ETT depth calculated from initial chest radiographs and the clinical depth of the ETT after adjustments to predicted depths using weight and gestational age-based estimates.

RESULTS

 The standard anatomic depth was deeper than age (standard deviation 1.29 ± 1.15 cm, p < 0.001) and weight-based (standard deviation 0.59 ± 0.95 cm, p < 0.001) estimates. The clinical ETT depth was also deeper than age (standard deviation 1.01 ± 0.77 cm, p < 0.001) and weight-based (standard deviation 0.26 ± 0.50 cm, p < 0.001) estimates.

CONCLUSION

 Established strategies to predict ETT depth underestimate the ideal depth in infants with left-sided CDH. These data suggest utilizing caution during initial ETT placement based on standard depth estimates for patients with CDH.

KEY POINTS

· CDH patients present unique stabilization challenges.. · Standard ETT depth estimates are too shallow.. · Resuscitation teams should cautiously choose ETT depth..

Lung-protective ventilation in the management of congenital diaphragmatic hernia

Prioritizing lung-protective ventilation has produced a clear mortality benefit in neonates with congenital diaphragmatic hernia (CDH). While there is a paucity of CDH-specific evidence to support any particular approach to lung-protective ventilation, a growing body of data in adults is beginning to clarify the mechanisms behind ventilator-induced lung injury and inform safer management of mechanical ventilation in general. This review summarizes the adult data and attempts to relate the findings, conceptually, to the CDH population. Critical lessons from the adult studies are that much of the damage done during conventional mechanical ventilation affects normal lung tissue and that most of this damage occurs at the low-volume and high-volume extremes of the respiratory cycle. Consequently, it is important to prevent atelectasis by using sufficient positive end-expiratory pressure while also avoiding overdistention by scaling tidal volume to the amount of functional lung tissue rather than body weight. Paralysis early in acute respiratory distress syndrome improves outcomes, possibly because consistent respiratory mechanics facilitate avoidance of both atelectasis and overdistention-a mechanism that may also apply to the CDH population. Volume-targeted conventional modes may be advantageous in CDH, but determining optimal tidal volume is challenging. Both high-frequency oscillatory ventilation and high-frequency jet ventilation have been used successfully as 'rescue modes' to avoid extracorporeal membrane oxygenation, and a prospective trial comparing the two high-frequency modalities as the primary ventilation strategy for CDH is underway.

Risk Factors for Preoperative Pneumothorax in Neonates With Isolated Left-Sided Congenital Diaphragmatic Hernia: An International Cohort Study

BACKGROUND

We aimed to investigate the clinical characteristics and outcomes of patients with isolated left-sided congenital diaphragmatic hernia (CDH) who developed preoperative pneumothorax and determine its risk factors.

METHODS

We performed an international cohort study of patients with CDH enrolled in the Congenital Diaphragmatic Hernia Study Group registry between January 2015 and December 2020. The main outcomes assessed included survival to hospital discharge and preoperative pneumothorax development. The cumulative incidence of pneumothorax was estimated by the Gray test. The Fine and Gray competing risk regression model was used to identify the risk factors for pneumothorax.

RESULTS

Data for 2858 neonates with isolated left-sided CDH were extracted; 224 (7.8%) developed preoperative pneumothorax. Among patients with a large diaphragmatic defect, those with pneumothorax had a significantly lower rate of survival to discharge than did those without. The competing risks model demonstrated that a patent ductus arteriosus with a right-to-left shunt flow after birth (hazard ratio [HR]: 1.78; 95% confidence interval [CI]: 1.21-2.63; p = 0.003) and large defects (HR: 1.65; 95% CI: 1.13-2.42; p = 0.01) were associated with an increased risk of preoperative pneumothorax. Significant differences were observed in the cumulative incidence of pneumothorax depending on defect size and shunt direction (p < 0.001).

CONCLUSIONS

Pneumothorax is a significant preoperative complication associated with increased mortality in neonates with CDH, particularly in cases with large defects. Large diaphragmatic defects and persistent pulmonary hypertension were found to be risk factors for preoperative pneumothorax development.

LEVEL OF EVIDENCE

LEVEL Ⅲ Retrospective Comparative Study.

Early Ventilator Management for Infants With Congenital Diaphragmatic Hernia: Impact of a Standardized Clinical Practice Guideline

BACKGROUND

Infants with congenital diaphragmatic hernia (CDH) experience high morbidity and mortality due to pulmonary arterial hypertension and hypoplasia. Mechanical ventilation is a central component of CDH management. Our objective was to evaluate the impact of a standardized clinical practice guideline (implemented in January 2012) on ventilator management for infants with CDH, and associate management changes with short-term outcomes, specifically extracorporeal membrane oxygenation (ECMO) utilization and survival to discharge.

METHODS

We conducted a retrospective pre-post study of 103 CDH infants admitted from January 2007-July 2021, divided pre- (n = 40) and post-guideline (n = 63). Clinical outcomes, ventilator settings, and blood gas values in the first 7 days of mechanical ventilation were compared between the pre- and post-guideline cohorts.

RESULTS

Post-guideline, ECMO utilization decreased (11% vs 38%, p = 0.001) and survival to discharge improved (92% vs 68%, p = 0.001). More post-guideline patients remained on conventional mechanical ventilation without need for escalation to high-frequency ventilation or ECMO, and had higher pressures and PaCO2 with lower FiO2 and PaO2 (p < 0.05).

CONCLUSIONS

Standardized ventilator management optimizing pressures for adequate lung expansion and minimizing oxygen toxicity improves outcomes for infants with CDH.

LEVEL OF EVIDENCE

III.

Congenital diaphragmatic hernia: quality improvement using a maximal lung protection strategy and early surgery-improved survival

To evaluate the effectiveness of a novel protocol, adopted in our institution, as a quality improvement project for congenital diaphragmatic hernia (CDH). A maximal lung protection (MLP) protocol was implemented in 2019. This strategy included immediate use of high-frequency oscillatory ventilation (HFOV) after birth, during the stay at the Neonatal Intensive Care Unit (NICU), and during surgical repair. HFOV strategy included low distending pressures and higher frequencies (15 Hz) with subsequent lower tidal volumes. Surgical repair was performed early, within 24 h of birth, if possible. A retrospective study of all inborn neonates prenatally diagnosed with CDH and without major associated anomalies was performed at the NICU of Schneider Children's Medical Center of Israel between 2009 and 2022. Survival rates and pulmonary outcomes of neonates managed with MLP were compared to the historical standard care cohort. Thirty-three neonates were managed with the MLP protocol vs. 39 neonates that were not. Major adverse outcomes decreased including death rate from 46 to 18% (p = 0.012), extracorporeal membrane oxygenation from 39 to 0% (p < 0.001), and pneumothorax from 18 to 0% (p = 0.013).

CONCLUSION

 MLP with early surgery significantly improved survival and additional adverse outcomes of neonates with CDH. Prospective randomized studies are necessary to confirm the findings of the current study.

WHAT IS KNOWN

• Ventilator-induced lung injury was reported as the main cause of mortality in neonates with congenital diaphragmatic hernia (CDH). • Conventional ventilation is recommended by the European CDH consortium as the first-line ventilation modality; timing of surgery is controversial.

WHAT IS NEW

• A maximal lung protection strategy based on 15-Hz high-frequency oscillatory ventilation with low distending pressures as initial modality and early surgery significantly reduced mortality and other outcomes.

High-Frequency Positive Pressure Ventilation as Primary Rescue Strategy for Patients with Congenital Diaphragmatic Hernia: A Comparison to High-Frequency Oscillatory Ventilation

OBJECTIVE

The aim of this article was to evaluate high-frequency positive pressure ventilation (HFPPV) compared with high-frequency oscillatory ventilation (HFOV) as a rescue ventilation strategy for patients with congenital diaphragmatic hernia (CDH). HFPPV is a pressure-controlled conventional ventilation method utilizing high respiratory rate and low positive end-expiratory pressure.

STUDY DESIGN

Seventy-seven patients diagnosed with CDH from January 2005 to September 2019 who were treated with stepwise progression from HFPPV to HFOV versus only HFOV were included. Fisher's exact test and the Kruskal-Wallis test were used to compare outcomes.

RESULTS

Patients treated with HFPPV + HFOV had higher survival to discharge (80 vs. 50%, p = 0.007) and to surgical intervention (95.6 vs. 68.8%, p = 0.003), with average age at repair 2 days earlier (p = 0.004). Need for extracorporeal membrane oxygenation (p = 0.490), inhaled nitric oxide (p = 0.585), supplemental oxygen (p = 0.341), and pulmonary hypertension medications (p = 0.381) were similar.

CONCLUSION

In CDH patients who fail respiratory support with conventional ventilation, HFPPV may be used as an intermediary mode of rescue ventilation prior to HFOV without adverse effects.

KEY POINTS

· HFPPV may be used as an intermediary mode of rescue ventilation prior to HFOV without adverse effect.. · HFPPV is more widely available and can mitigate the limitations faced when using HFOV.. · HFPPV allows for intra- or interhospital transfer of neonates with CDH..

Unique Cardiopulmonary Interactions in Congenital Diaphragmatic Hernia: Physiology and Therapeutic Implications

Congenital diaphragmatic hernia (CDH) results in abdominal contents entering the thoracic cavity, affecting both cardiac and pulmonary development. Maldevelopment of the pulmonary vasculature occurs within both the ipsilateral lung and the contralateral lung. The resultant bilateral pulmonary hypoplasia and associated pulmonary hypertension are important components of the pathophysiology of this disease that affect outcomes. Despite prenatal referral to specialized high-volume centers, advanced ventilation strategies, pulmonary hypertension management, and the option of extracorporeal membrane oxygenation, overall CDH mortality remains between 25% and 30%. With increasing recognition that cardiac dysfunction plays a large role in morbidity and mortality in patients with CDH, it becomes imperative to understand the different clinical phenotypes, thus allowing for individual patient-directed therapies. Further research into therapeutic interventions that address the cardiopulmonary interactions in patients with CDH may lead to improved morbidity and mortality outcomes.

Pathological findings in congenital diaphragmatic hernia on necropsy studies: A single-center case series

INTRODUCTION

Congenital diaphragmatic hernia (CDH) is associated with high mortality rates and significant pulmonary morbidities. The objective of this study was to delineate the histopathological features observed in necropsies of CDH patients and correlate these with their clinical manifestations.

METHODS

We retrospectively reviewed the postmortem findings and corresponding clinical characteristics in eight CDH cases from 2017 to July 2022.

RESULTS

The median survival time was 46 (8-624) hours. Autopsy reports showed that diffuse alveolar damage (congestion and hemorrhage) and hyaline membrane formation were the primary pathological lung changes observed. Notably, despite significant reduction in lung volume, the lung development appeared normal in 50% of the cases, while lobulated deformities were present in three (37.5%) cases. All patients displayed a large patent ductus arteriosus (PDA) and a patent foramen ovale, resulting in increased right ventricle (RV) volume, and myocardial fibers appeared slightly congested and swollen. The pulmonary vessels indicated thickening of the arterial media and adventitia. Lung hypoplasia and diffuse lung damage resulted in impaired gas exchange, while PDA and pulmonary hypertension led to RV failure, subsequent organ dysfunction and ultimately death.

CONCLUSIONS

Patients with CDH typically succumb to cardiopulmonary failure, a condition driven by a complex interplay of pathophysiological factors. This complexity accounts for the unpredictable response to currently available vasodilators and ventilation therapies.

Management of the CDH patient on ECLS

Congenital diaphragmatic hernia (CDH) is the most common indication for respiratory extracorporeal life support (ECLS) in neonates. The survival rate of CDH neonates treated with ECLS is 50%, and this figure has remained relatively stable over the last few decades. This is likely because the current population of CDH neonates who require ECLS have a higher risk profile [1]. The management of neonates with CDH has evolved over time to emphasize postnatal stabilization, gentle ventilation, and multi-modal treatment of pulmonary hypertension. In order to minimize practice variation, many centers have adopted CDH-specific clinical practice guidelines, however care is not standardized between different centers and outcomes vary [3]. The purpose of this review is to summarize our current understanding of issues central to the care of neonates with CDH treated with ECLS and specifically highlight how the use of the Extracorporeal Life Support Organization (ELSO) data have added to our understanding of CDH.

The use of neurally-adjusted ventilatory assist (NAVA) for infants with congenital diaphragmatic hernia (CDH)

OBJECTIVES

Newborns with congenital diaphragmatic hernia (CDH) can have complex respiratory problems which are worsened by ventilatory induced lung injury. Neurally adjusted ventilator assist (NAVA) is a potentially promising ventilation mode for this population, as it can result in improved patient-ventilator interactions and provision of adequate gas exchange at lower airway pressures.

CONTENT

A literature review was undertaken to provide an overview of NAVA and examine its role in the management of infants with CDH.

SUMMARY

NAVA in neonates has been used in CDH infants who were stable on ventilatory support or being weaned from mechanical ventilation and was associated with a reduction in the level of respiratory support.

OUTLOOK

There is, however, limited evidence regarding the efficacy of NAVA in infants with CDH, with only short-term benefits being investigated. A prospective, multicentre study with long term follow-up is required to appropriately assess NAVA in this population.

Work of breathing at different tidal volume targets in newborn infants with congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) results in varying degrees of pulmonary hypoplasia. Volume targeted ventilation (VTV) is a lung protective strategy but the optimal target tidal volume in CDH infants has not previously been studied. The aim of this study was to test the hypothesis that low targeted volumes would be better in CDH infants as determined by measuring the work of breathing (WOB) in CDH infants, at three different targeted tidal volumes. A randomised cross-over study was undertaken. Infants were eligible for inclusion in the study after surgical repair of their diaphragmatic defect. Targeted tidal volumes of 4, 5, and 6 ml/kg were each delivered in random order for 20-min periods with 20-min periods of baseline ventilation between. WOB was assessed and measured by using the pressure-time product of the diaphragm (PTPdi). Nine infants with a median gestational age at birth of 38 + 4 (range 36 + 4-40 + 6) weeks and median birth weight 3202 (range 2855-3800) g were studied. The PTPdi was higher at 4 ml/kg than at both 5, p = 0.008, and 6 ml/kg, p = 0.012.

CONCLUSION

VTV of 4 ml/kg demonstrated an increased PTPdi compared to other VTV levels studied and should be avoided in post-surgical CDH infants.

WHAT IS KNOWN

• Lung injury secondary to mechanical ventilation increases the mortality and morbidity of infants with CDH. • Volume targeted ventilation (VTV) reduces 'volutrauma' and ventilator-induced lung injury in other neonatal intensive care populations.

WHAT IS NEW

• A randomised cross-over trial was carried out investigating the response to different VTV levels in infants with CDH. • Despite pulmonary hypoplasia being a common finding in CDH, a VTV of 5ml/kg significantly reduced the work of breathing in infants with CDH compared to a lower VTV level.

Neonatal pneumothorax in congenital diaphragmatic hernia: Be wary of high ventilatory pressures

Background

Patients with congenital diaphragmatic hernia (CDH) require invasive respiratory support and higher ventilator pressures may be associated with barotrauma. We sought to evaluate the risk factors associated with pneumothorax in CDH neonates prior to repair.

Methods

We retrospectively reviewed newborns born with CDH between 2014 and 2019 who developed a pneumothorax, and we matched these cases to patients with CDH without pneumothorax.

Results

Twenty-six patients were included (n=13 per group). The pneumothorax group required extracorporeal life support (ECLS) more frequently (85% vs 54%, p=0.04), particularly among type A/B defects (31% vs 7%, p=0.01). The pneumothorax group had higher positive end-expiratory pressure (PEEP) within 1 hour of birth (p=0.02), at pneumothorax diagnosis (p=0.003), and at ECLS (p=0.02). The pneumothorax group had a higher mean airway pressure (Paw) at birth (p=0.01), within 1 hour of birth (p=0.01), and at pneumothorax diagnosis (p=0.04). Using multiple logistic regression with cluster robust SEs, higher Paw (OR 2.2, 95% CI 1.08 to 3.72, p=0.03) and PEEP (OR 1.8, 95% CI 1.15 to 3.14, p=0.007) were associated with an increased risk of developing pneumothorax. There was no difference in survival (p=0.09).

Conclusions

Development of a pneumothorax in CDH neonates is independently associated with higher Paw and higher PEEP. A pneumothorax increases the likelihood of treated with ECLS, even with smaller defect.

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.

Efficacy of Intact Cord Resuscitation Compared to Immediate Cord Clamping on Cardiorespiratory Adaptation at Birth in Infants with Isolated Congenital Diaphragmatic Hernia (CHIC)

Resuscitation at birth of infants with Congenital Diaphragmatic Hernia (CDH) remains highly challenging because of severe failure of cardiorespiratory adaptation at birth. Usually, the umbilical cord is clamped immediately after birth. Delaying cord clamping while the resuscitation maneuvers are started may: (1) facilitate blood transfer from placenta to baby to augment circulatory blood volume; (2) avoid loss of venous return and decrease in left ventricle filling caused by immediate cord clamping; (3) prevent initial hypoxemia because of sustained uteroplacental gas exchange after birth when the cord is intact. The aim of this trial is to evaluate the efficacy of intact cord resuscitation compared to immediate cord clamping on cardiorespiratory adaptation at birth in infants with isolated CDH. The Congenital Hernia Intact Cord (CHIC) trial is a prospective multicenter open-label randomized controlled trial in two balanced parallel groups. Participants are randomized either immediate cord clamping (the cord will be clamped within the first 15 s after birth) or to intact cord resuscitation group (umbilical cord will be kept intact during the first part of the resuscitation). The primary end-point is the number of infants with APGAR score <4 at 1 min or <7 at 5 min. One hundred eighty participants are expected for this trial. To our knowledge, CHIC is the first study randomized controlled trial evaluating intact cord resuscitation on newborn infant with congenital diaphragmatic hernia. Better cardiorespiratory adaptation is expected when the resuscitation maneuvers are started while the cord is still connected to the placenta.

Impacts of Respiratory Muscle Training on Respiratory Functions, Maximal Exercise Capacity, Functional Performance, and Quality of Life in School-Aged Children with Postoperative Congenital Diaphragmatic Hernia

Objectives

Congenital diaphragmatic hernia (CDH) is a birth defect affecting the respiratory functions, functional performance, and quality of life (QOL) in school-aged children. Rarely have studies been conducted to evaluate the impacts of respiratory muscle training on school-aged children with postoperative CDH. The current study was designed to evaluate the impacts of respiratory muscle training on respiratory function, maximal exercise capacity, functional performance, and QOL in these children.

Methods

This study is a randomized control study. 40 children with CDH (age: 9-11 years) were assigned randomly into two groups. The first group conducted an incentive spirometer exercise combined with inspiratory muscle training (study group, n = 20), whereas the second group conducted only incentive spirometer exercise (control group, n = 20), thrice weekly for twelve consecutive weeks. Respiratory functions, maximal exercise capacity, functional performance, and pediatric quality of life inventory (PedsQL) were assessed before and after the treatment program. Results. Regarding the posttreatment analysis, the study group showed significant improvements in all outcome measures (FVC%, p < 0.001; FEV1%, p = 0.002; VO₂max, p = 0.008; VE/VCO₂ slope, p = 0.002; 6-MWT, p < 0.001; and PedsQL, p < 0.001), whereas the control group did not show significant changes (p > 0.05).

Conclusion

Respiratory muscle training may improve respiratory functions, maximal exercise capacities, functional performance, and QOL in children with postoperative CDH. Clinical commendations have to be considered to include respiratory muscle training in pulmonary rehabilitation programs in children with a history of CDH.

Risk factors for pneumothorax associated with isolated congenital diaphragmatic hernia: results of a Japanese multicenter study

PURPOSE

This study aimed to elucidate the clinical characteristics of neonates with congenital diaphragmatic hernia (CDH) associated with pneumothorax and evaluate the risk factors for the development of pneumothorax.

METHODS

A retrospective cohort study was conducted in the 15 institutions participating in the Japanese CDH Study Group. A total of 495 neonates with isolated CDH who were born between 2011 and 2018 were analyzed in this study.

RESULTS

Among the 495 neonates with isolated CDH, 52 (10.5%) developed pneumothorax. Eighteen (34.6%) patients developed pneumothorax before surgery, while 34 (65.4%) developed pneumothorax after surgery. The log-rank test showed that the cumulative survival rate was significantly lower in patients with pneumothorax than in those without pneumothorax. Univariate analysis revealed significant differences between patients with pneumothorax and those without pneumothorax with regard to the best oxygenation index within 24 h after birth, mean airway pressure (MAP) higher than 16 cmH₂O, diaphragmatic defect size, and need for patch closure. Multiple logistic regression analysis indicated that only the MAP was associated with an increased risk of pneumothorax.

CONCLUSIONS

The cumulative survival rate was significantly lower in isolated CDH patients with pneumothorax than in those without pneumothorax. A higher MAP was a risk factor for pneumothorax in CDH patients.

Evaluation of Lung Injury in Infants with Congenital Diaphragmatic Hernia

BACKGROUND/PURPOSE

The presence of lung injury and the factors that contribute to it in infants with congenital diaphragmatic hernia (CDH) have not been objectively measured during their clinical course. In adults with acute respiratory distress syndrome, higher serum levels of surfactant protein D (SP-D) are linked to lung injury and worse outcomes. We hypothesized that serum SP-D levels would be elevated in CDH infants and that the levels would correlate to the amount of lung injury present.

METHODS

In this retrospective cohort study, serum SP-D levels were analyzed in 37 CDH infants and 5 control infants using a commercially available enzyme-linked immunosorbent assay kit.

RESULTS

Infants with more severe CDH had a statistically significant increase (p < 0.001) in serum SP-D over their first month of life. SP-D levels in CDH infants were similar to control infants while on extracorporeal membrane oxygenation (ECMO) but were 2.5-fold higher (p = 0.03) than controls following ECMO termination. SP-D levels increased 1.6-fold following surgical repair of the diaphragm and were significantly higher in the second week following surgery when compared to pre-operative levels (p < 0.03).

CONCLUSIONS

These results demonstrate that CDH infants experience lung injury during the first week of life, around the time of surgery, and at the time of ECMO termination. Level II prognosis study.

Lower Distending Pressure Improves Respiratory Mechanics in Congenital Diaphragmatic Hernia Complicated by Persistent Pulmonary Hypertension

OBJECTIVE

To investigate the effects of distending pressures on respiratory mechanics and pulmonary circulation in newborn infants with congenital diaphragmatic hernia (CDH) and persistent pulmonary hypertension (PPHN).

STUDY DESIGN

In total, 17 consecutive infants of ≥37 weeks of gestational age with CDH and PPHN were included in this prospective, randomized, crossover pilot study. Infants were assigned randomly to receive 2 or 5 cmH₂O of positive end-expiratory pressure (PEEP) for 1 hour in a crossover design. The difference between peak inspiratory pressure and PEEP was kept constant. Respiratory mechanics, lung function, and hemodynamic variables assessed by Doppler echocardiography were measured after each study period.

RESULTS

At 2 cmH₂O of PEEP, tidal volume and minute ventilation were greater (P < .05), and respiratory system compliance was 30% greater (P < .05) than at 5 cmH₂O. PaCO₂ and ventilation index were lower at 2 cmH₂O than at 5 cmH₂O (P < .05). Although preductal peripheral oxygen saturation was similar at both PEEP levels, postductal peripheral oxygen saturation was lower (median [range]: 81% [65-95] vs 91% [71-100]) and fraction of inspired oxygen was greater (35% [21-70] vs 25% [21-60]) at 5 cmH₂O. End-diastolic left ventricle diameter, left atrium/aortic root ratio, and pulmonary blood flow velocities in the left pulmonary artery were lower at 5 cmH₂O.

CONCLUSIONS

After surgical repair, lower distending pressures result in better respiratory mechanics in infants with mild-to-moderate CDH. We speculate that hypoplastic lungs in CDH are prone to overdistension, with poor tolerance to elevation of distending pressure.

Ventilation modalities in infants with congenital diaphragmatic hernia

Neonates with congenital diaphragmatic hernia are among the more complex patients to support with mechanical ventilation. They have particular features that add to the difficulties already present in the neonatal patient. A ventilation strategy tailored to the patient's underlying physiology rather than mode of ventilation is a crucial issue for clinicians treating these delicate patients.

Congenital Diaphragmatic hernia - a review

Congenital Diaphragmatic hernia (CDH) is a condition characterized by a defect in the diaphragm leading to protrusion of abdominal contents into the thoracic cavity interfering with normal development of the lungs. The defect may range from a small aperture in the posterior muscle rim to complete absence of diaphragm.

The pathophysiology of CDH is a combination of lung hypoplasia and immaturity associated with persistent pulmonary hypertension of newborn (PPHN) and cardiac dysfunction. Prenatal assessment of lung to head ratio (LHR) and position of the liver by ultrasound are used to diagnose and predict outcomes. Delivery of infants with CDH is recommended close to term gestation. Immediate management at birth includes bowel decompression, avoidance of mask ventilation and endotracheal tube placement if required. The main focus of management includes gentle ventilation, hemodynamic monitoring and treatment of pulmonary hypertension followed by surgery. Although inhaled nitric oxide is not approved by FDA for the treatment of PPHN induced by CDH, it is commonly used.

Extracorporeal membrane oxygenation (ECMO) is typically considered after failure of conventional medical management for infants ≥ 34 weeks’ gestation or with weight >2 kg with CDH and no associated major lethal anomalies. Multiple factors such as prematurity, associated abnormalities, severity of PPHN, type of repair and need for ECMO can affect the survival of an infant with CDH. With advances in the management of CDH, the overall survival has improved and has been reported to be 70-90% in non-ECMO infants and up to 50% in infants who undergo ECMO.

Management of congenital diaphragmatic hernia: A systematic review from the APSA outcomes and evidence based practice committee

OBJECTIVE

Variable management practices complicate the identification of optimal strategies for infants with congenital diaphragmatic hernia (CDH). This review critically appraises the available evidence to provide recommendations.

METHODS

Six questions regarding CDH management were generated. English language articles published between 1980 and 2014 were compiled after searching Medline, Cochrane, Embase and Web of Science. Given the paucity of literature on the subject, all studies irrespective of their rank in the levels of evidence hierarchy were included.

RESULTS

Gentle ventilation with permissive hypercapnia provides the best outcomes. Initial high frequency ventilation may be considered but its overall efficacy is unproven. Routine inhaled nitric oxide (iNO) or other medical adjuncts for acute, severe pulmonary hypertension demonstrate no benefit. Evidence does not support routine administration of pre- or postnatal glucocorticoids. Mode of extracorporeal membrane oxygenation (ECMO) has little bearing on outcomes. While the overall timing of repair does not impact outcomes, early repair on ECMO has benefits. Open repair leads to significantly fewer recurrences. Polytetrafluoroethylene (PTFE) is the most durable patch repair material.

CONCLUSIONS

Limited high-level evidence prevents the development of robust management guidelines for CDH. Prospective, multi-institutional studies are needed to identify best practices and optimize outcomes.

Survival of outborns with congenital diaphragmatic hernia: the role of protective ventilation, early presentation and transport distance: a retrospective cohort study

Background

Congenital diaphragmatic hernia (CDH) is a congenital malformation associated with life-threatening pulmonary dysfunction and high neonatal mortality. Outcomes are improved with protective ventilation, less severe pulmonary pathology, and the proximity of the treating center to the site of delivery. The major CDH treatment center in Croatia lacks a maternity ward, thus all CDH patients are transferred from local Zagreb hospitals or remote areas (outborns). In 2000 this center adopted protective ventilation for CDH management. In the present study we assess the roles of protective ventilation, transport distance, and severity of pulmonary pathology on survival of neonates with CDH.

Methods

The study was divided into Epoch I, (1990–1999, traditional ventilation to achieve normocapnia), and Epoch II, (2000–2014, protective ventilation with permissive hypercapnia). Patients were categorized by transfer distance (local hospital or remote locations) and by acuity of respiratory distress after delivery (early presentation-occurring at birth, or late presentation, ≥6 h after delivery). Survival between epochs, types of transfers, and acuity of presentation were assessed. An additional analysis was assessed for the potential association between survival and end-capillary blood CO₂ (P_cCO₂), an indirect measure of pulmonary pathology.

Results

There were 83 neonates, 26 in Epoch I, and 57 in Epoch II. In Epoch I 11 patients (42 %) survived, and in Epoch II 38 (67 %) (P = 0.039). Survival with early presentation (N = 63) was 48 % and with late presentation 95 % (P <0.001). Among early presentation, survival was higher in Epoch II vs. Epoch I (57 % vs. 26 %, P = 0.031). From multiple logistic regression analysis restricted to neonates with early presentation and adjusting for severity of disease, survival was improved in Epoch II (OR 4.8, 95%CI 1.3–18.0, P = 0.019). Survival was unrelated to distance of transfer but improved with lower partial pressure of P_cCO₂ on admission (OR 1.16, 95%CI 1.01–1.33 per 5 mmHg decrease, P = 0.031).

Conclusions

The introduction of protective ventilation was associated with improved survival in neonates with early presentation. Survival did not differ between local and remote transfers, but primarily depended on severity of pulmonary pathology as inferred from admission capillary PcCO₂.

Lung function over the first 3 years of life in children with congenital diaphragmatic hernia

OBJECTIVES

Infants with congenital diaphragmatic hernia (CDH) have variable degrees of pulmonary hypoplasia at birth. Few reports of lung function over the first years of life exist in this group of children.

HYPOTHESIS

Pulmonary function abnormalities correlate with severity of neonatal disease and intensity of neonatal therapies needed. We also hypothesized that longitudinal measurements of lung function over the usual period of rapid lung growth would lend some insight into how the lung remodels in CDH infants.

METHODOLOGY

Ninety-eight infants with CDH between 11 days and 44 months of age underwent pulmonary function testing (PFT) on 1-5 occasions using the raised volume rapid thoracic compression technique. Demographic data were also collected.

MAIN RESULTS

Forced expiratory flows were below normal. Total lung capacity was normal, but residual volume and functional residual capacity were elevated. Children requiring patch closure, ECMO, or pulmonary vasodilators generally had lower lung functions at follow up. Additionally, longer duration of mechanical ventilation correlated with worse lung function.

CONCLUSIONS

Lung functions of survivors of CDH remain abnormal throughout the first 3 years of life. The degree of pulmonary function impairment correlated both with markers of the initial degree of pulmonary hypoplasia and the duration of mechanical ventilation. Understanding the relationship between the phenotypic presentation of CDH and the potential for subsequent lung growth could help refine both pre- and postnatal therapies to optimize lung growth in CDH infants.

Acute Neonatal Respiratory Failure

Acute respiratory failure requiring assisted ventilation is one of the most common reasons for admission to the neonatal intensive care unit. Respiratory failure is the inability to maintain either normal delivery of oxygen to the tissues or normal removal of carbon dioxide from the tissues. It occurs when there is an imbalance between the respiratory workload and ventilatory strength and endurance. Definitions are somewhat arbitrary but suggested laboratory criteria for respiratory failure include two or more of the following: PaCO₂ > 60 mmHg, PaO₂ < 50 mmHg or O₂ saturation <80 % with an FiO₂ of 1.0 and pH < 7.25 (Wen et al. 2004).

Controversies in the management of severe congenital diaphragmatic hernia

Despite years of progress in perinatal care, severe congenital diaphragmatic hernia (CDH) remains a clinical challenge. Controversies include almost every facet of clinical care: the definition of severe CDH by prenatal and postnatal criteria, fetal surgical intervention, ventilator management, pulmonary hypertension management, use of extracorporeal membrane oxygenation, surgical considerations, and long-term follow-up. Breakthroughs are likely only possible by sharing of experience, collaboration between institutions and innovative therapies within well-designed multicenter clinical trials.

Repair of congenital diaphragmatic hernia under high-frequency oscillatory ventilation in high-risk patients: an opportunity for earlier repair while minimizing lung injury

BACKGROUND

Repair of congenital diaphragmatic hernia (CDH) is ideally delayed until ventilatory parameters are stabilized and patients are switched to conventional ventilation. However, in selected high-risk patients, repair can be performed earlier while they are still on high-frequency oscillatory ventilation (HFOV).

DESIGN AND SETTINGS

A retrospective review of all CDH cases treated in our tertiary referral center between 1997 and 2013.

METHODS

In 1997, we started repairing selected high-risk CDH cases under HFOV with or without inhaled nitric oxide (iNO). All repairs were performed once the infants' blood gas levels were acceptable. The infants were gradually weaned to conventional ventilation followed by extubation as their ventilatory parameters improved. Their records were reviewed to determine the group-wide outcomes.

RESULTS

Between 1997 and 2013, 55 infants with CDH were treated in our institute; of these 12 high-risk cases were repaired under HFOV/iNO combinations and 1 was repaired without iNO. All patients had significant pulmonary hypertension and 8 had herniated livers. The mean age at repair was 9.1 (6.3) days. Two mortalities occurred at the first and tenth postoperative days. Among the remaining 11 survivors, the median ventilation and hospitalization days were 29.5 (11-84) and 45.5 (25-107), respectively, and the median duration under HFOV and conventional ventilation days were 15 (9-40) and 12 (3-47), respectively.

CONCLUSION

CDH repair can be performed earlier under HFOV and iNO. The possible advantages are earlier restoration of normal anatomy and earlier start of enteral feeding while minimizing the risk of lung injury.

Predictors of neonatal morbidity in fetuses with severe isolated congenital diaphragmatic hernia undergoing fetoscopic tracheal occlusion

OBJECTIVES

To investigate neonatal morbidity in fetuses with severe congenital diaphragmatic hernia (CDH) treated with fetoscopic endoluminal tracheal occlusion (FETO) and compare it with historical controls with less severe forms of CDH that were managed expectantly.

METHODS

This was a prospective, multicenter study on neonatal outcomes and prenatal predictors in 90 FETO survivors (78 left-sided, 12 right) and 41 controls from the antenatal CDH registry with either severe or moderate hypoplasia who were managed expectantly. We also investigated early neonatal morbidity indicators, including the need for patch repair, duration of mechanical ventilation and supplemental oxygen, age at full enteral feeding and incidence of pulmonary hypertension.

RESULTS

Gestational age at delivery was predictive of duration of assisted ventilation (P = 0.046), days on supplemental oxygen (P = 0.019) and age at full enteral feeding (P = 0.020). When delivery took place after 34 weeks' gestation, neonatal morbidity of FETO cases was comparable with that of expectantly managed cases with moderate hypoplasia.

CONCLUSIONS

Fetal intervention for severe CDH is associated with neonatal morbidity that is comparable with that of an expectantly managed group with less severe disease.

Congenital diaphragmatic hernia and protective ventilation strategies in pediatric surgery

Infants affected with congenital diaphragmatic hernias (CDH) suffer from some degree of respiratory insufficiency arising from a combination of pulmonary hypoplasia and pulmonary hypertension. Respiratory care strategies to optimize blood gasses lead to significant barotrauma, increased morbidity, and overuse of extracorporeal membrane oxygenation (ECMO). Newer permissive hypercapnia/spontaneous ventilation protocols geared to accept moderate hypercapnia at lower peak airway pressures have led to improved outcomes. High-frequency oscillatory ventilation can be used in infants who continue to have persistent respiratory distress despite conventional ventilation. ECMO can be used successfully as a resuscitative strategy to minimize further barotrauma in carefully selected patients.

[Congenital diaphragmatic hernia: respiratory and vascular outcomes]

Congenital diaphragmatic hernia (CDH) is a life-threatening anomaly associated with a variable degree of pulmonary hypoplasia (PH) and persistent pulmonary hypertension (PPH). Despite remarkable advances in neonatal resuscitation and intensive care, and new postnatal treatment strategies, the rates of mortality and morbidity in the newborn with CDH remain high as the result of severe respiratory failure secondary to PH and PPH. Later, lung function assessments show obstructive and restrictive impairments due to altered lung structure and lung damage due to prolonged ventilatory support. The long-term consequences of pulmonary hypertension are unknown. Other problems include chronic pulmonary aspiration caused by gastro-oesophageal reflux and respiratory manifestations of allergy such as asthma or rhinitis. Finally, failure to thrive may be caused by increased caloric requirements due to pulmonary morbidity. Follow-up studies that systematically assess long-term sequelae are needed. Based on such studies, a more focused approach for routine multidisciplinary follow-up programs could be established. It is the goal of the French Collaborative Network to promote exchange of knowledge, future research and development of treatment protocols.

Is the time necessary to obtain preoperative stabilization a predictive index of outcome in neonatal congenital diaphragmatic hernia?

Background. The study aims to verify if the time of preoperative stabilization (≤24 or >24 hours) could be predictive for the severity of clinical condition among patients affected by congenital diaphragmatic hernia. Methods. 55 of the 73 patients enrolled in the study achieved presurgical stabilization and underwent surgical correction. Respiratory and hemodynamic indexes, postnatal scores, the need for advanced respiratory support, the length of HFOV, tracheal intubation, PICU, and hospital stay were compared between patients reaching stabilization in ≤24 or >24 hours. Results. Both groups had a 100% survival rate. Neonates stabilized in ≤24 hours are more regular in the postoperative period and had an easier intensive care path; those taking >24 hours showed more complications and their care path was longer and more complex. Conclusions. The length of preoperative stabilization does not affect mortality, but is a valid parameter to identify difficulties in survivors' clinical pathway.

Congenital diaphragmatic hernia

Congenital Diaphragmatic Hernia (CDH) is defined by the presence of an orifice in the diaphragm, more often left and posterolateral that permits the herniation of abdominal contents into the thorax. The lungs are hypoplastic and have abnormal vessels that cause respiratory insufficiency and persistent pulmonary hypertension with high mortality. About one third of cases have cardiovascular malformations and lesser proportions have skeletal, neural, genitourinary, gastrointestinal or other defects. CDH can be a component of Pallister-Killian, Fryns, Ghersoni-Baruch, WAGR, Denys-Drash, Brachman-De Lange, Donnai-Barrow or Wolf-Hirschhorn syndromes. Some chromosomal anomalies involve CDH as well. The incidence is < 5 in 10,000 live-births. The etiology is unknown although clinical, genetic and experimental evidence points to disturbances in the retinoid-signaling pathway during organogenesis. Antenatal diagnosis is often made and this allows prenatal management (open correction of the hernia in the past and reversible fetoscopic tracheal obstruction nowadays) that may be indicated in cases with severe lung hypoplasia and grim prognosis. Treatment after birth requires all the refinements of critical care including extracorporeal membrane oxygenation prior to surgical correction. The best hospital series report 80% survival but it remains around 50% in population-based studies. Chronic respiratory tract disease, neurodevelopmental problems, neurosensorial hearing loss and gastroesophageal reflux are common problems in survivors. Much more research on several aspects of this severe condition is warranted.

The VICI-trial: high frequency oscillation versus conventional mechanical ventilation in newborns with congenital diaphragmatic hernia: an international multicentre randomized controlled trial

BACKGROUND

Congenital diaphragmatic hernia (CDH) is a severe congenital anomaly of the diaphragm resulting in pulmonary hypoplasia and pulmonary hypertension. It is associated with a high risk of mortality and pulmonary morbidity. Previous retrospective studies have reported high frequency oscillatory ventilation (HFO) to reduce pulmonary morbidity in infants with CDH, while others indicated HFO to be associated with worse outcome. We therefore aimed to develop a randomized controlled trial to compare initial ventilatory treatment with high-frequency oscillation and conventional ventilation in infants with CDH.

METHODS/DESIGN

This trial is designed as a multicentre trial in which 400 infants (200 in each arm) will be included. Primary outcome measures are BPD, described as oxygen dependency by day 28 according to the definition of Jobe and Bancalari, and/or mortality by day 28. All liveborn infants with CDH born at a gestational age of over 34 weeks and no other severe congenital anomalies are eligible for inclusion. Parental informed consent is asked antenatally and the allocated ventilation mode starts within two hours after birth. Laboratory samples of blood, urine and tracheal aspirate are taken at the first day of life, day 3, day 7, day 14 and day 28 to evaluate laboratory markers for ventilator-induced lung injury and pulmonary hypertension.

DISCUSSION

To date, randomized clinical trials are lacking in the field of CDH. The VICI-trial, as the first randomized clinical trial in the field of CDH, may provide further insight in ventilation strategies in CDH patient. This may hopefully prevent mortality and morbidity.

TRIAL REGISTRATION

Netherlands Trial Register (NTR): NTR1310.

Preliminary observations of the use of high-frequency jet ventilation as rescue therapy in infants with congenital diaphragmatic hernia

BACKGROUND/PURPOSE

Congenital diaphragmatic hernia (CDH) is associated with mortality of 10% to 50%. Several investigators have reported outcomes from centers using high-frequency oscillatory ventilation in their management of CDH, but there are no recent reports on use of high-frequency jet ventilation.

METHODS

During the study period from January 2001 until August 2007, infants with CDH who were cared for at Duke University Medical Center received high-frequency jet ventilation as a rescue mode of high-frequency ventilation. We compared actual survival with predicted survival for infants treated only with conventional ventilation vs those rescued with high-frequency jet ventilation after failing conventional ventilation.

RESULTS

Survival for the 16 infants that received high-frequency jet ventilation was predicted to be 63%; actual survival was 75%. Survival for the 15 infants that received only conventional ventilation was predicted to be 83%; actual survival was 87%. We observed no significant survival benefit for high-frequency jet ventilation, 8.0% (95 confidence interval, -22.0% to 38.1%; P = .59).

CONCLUSIONS

Although our sample size was small, we conclude with consideration of the absolute results, the degree of illness of the infants, and the biologic plausibility for the intervention that high-frequency jet ventilation is an acceptable rescue ventilation mode for infants with CDH.

Engineering an artificial alveolar-capillary membrane: a novel continuously perfused model within microchannels

INTRODUCTION

Pulmonary hypoplasia is a condition of the newborn that is characterized by underdeveloped lungs and poor outcome. One strategy in the treatment of patients with hypoplasia is to augment underdeveloped lungs using biocompatible artificial lung tissue. However, one central challenge in current pulmonary tissue engineering efforts remains the development of a stable bio-mimetic alveolar-capillary membrane. Accordingly, we have built a series of bio-mimetic microfluidic devices that specifically model the alveolar-capillary membrane. Current designs include a single-layer microchip that exposes alveolar and endothelial cell types to controlled fluidic stimuli. A more advanced multi-layered device allows for alveolar cells to be cultured at an air interface while allowing constant media nourishment and waste removal, thus better mimicking the physiologic milieu of the alveolar-capillary interface. Both devices possess the benefit of parallel testing.

MATERIAL AND METHODS

Microdevices were fabricated using soft lithography in a biocompatible transparent polymeric material, polydimethyl siloxane, sealed covalently to glass. The multistage microdevice also integrated a suspended polyethylene terephthalate membrane connected via microfluidic channels to constant media and air access. Pulmonary endothelial (HMEC-1) and alveolar epithelial (A549) cell lines, along with fetal pulmonary cells (FPC) harvested from Swiss Webster mice at day 18 gestational age, were studied under multiple hydrodynamic shear conditions and liquid-to-cell ratio regimes. Cultures were examined for cell viability, function and proliferation to confluent monolayers. A549 cells cultured at an air-interface in a microdevice was also tested for their ability to maintain cell phenotype and function.

RESULTS

The single-layer differential flow microdevice allowed for a systematic determination of the optimal growth conditions of various lung-specific cell types in a microfluidic environment. Our device showed a greater surfactant based decrease in surface tension of the alveolar hypophase in A549 cultures exposed to air as compared to submerged cultures.

CONCLUSIONS

We have successfully developed biomimetic microfluidic devices that specifically allow stable alveolar cell growth at the air-liquid interface. This work serves prerequisite towards an implantable artificial alveolar membrane.

CONTEMPORARY NEONATAL INTENSIVE CARE MANAGEMENT IN CONGENITAL DIAPHRAGMATIC HERNIA: DOES THIS OBVIATE THE NEED FOR FETAL THERAPY?

The management of congenital diaphragmatic hernia (CDH) in the newborn infant has changed radically since the first successful outcomes were reported 60 years ago. Then it seemed a surgical problem with a surgical solution – do an operation, remove the intestines and solid viscera from the thoracic cavity, repair the defect and allow the lung to expand. CDH in that era was regarded as the quintessential neonatal surgical emergency. The expectation was that urgent surgery would result in improvement in lung function and oxygenation. That approach persisted up to the 1980s when it was realized that the problem was far more complex and involved both an abnormal pulmonary vascular bed as well as pulmonary hypoplasia. The use of systemically delivered pulmonary vasodilator therapy, principally tolazoline, became a focus of interest in the 1980s with small case reports and case series suggesting improved survival. In the 1990s, based on studies that showed worsening thoracic compliance and gas exchange following surgical repair, deferred surgery and pre-operative stabilization became the standard of care. At the same time extracorporeal membrane oxygenation (ECMO) was increasingly used either as part of pre-operative stabilization or as a rescue therapy after repair. Other centres chose to use high frequency oscillatory ventilation (HFOV). Despite all these innovations the survival in live born infants with CDH did not improve to more than 50% in large series published from high volume centres. However, in the past 10 years there has been an appreciable improvement in survival to the extent that many centres are now reporting survival rates of greater than 80%. Probably the biggest impact on this improvement has been the recognition of the role that ventilation induced lung injury plays in mortality and the need for ECMO rescue. This has ushered in an era of a lung protective or “gentle ventilation” strategy which has been widely adopted as a standard approach. While there have been these radical changes in postnatal management attempts have been made to improve outcome with prenatal interventions, starting with prenatal repair, which was abandoned because of preterm labour. More recently there has been increasing experience in the use of balloon occlusion of the trachea as a prenatal intervention strategy with patients being selected based on prenatal predictors of poor outcome. This approach can only be justified if those predictors can be validated and the outcomes (death or serious long term morbidity) can be shown to be better than those currently achievable, namely 80% survival in high volume CDH centres rather than the 50–60% survival frequently quoted in historical papers.

Can we improve outcome of congenital diaphragmatic hernia?

This review gives an overview of the disease spectrum of congenital diaphragmatic hernia (CDH). Etiological factors, prenatal predictors of survival, new treatment strategies and long-term morbidity are described. Early recognition of problems and improvement of treatment strategies in CDH patients may increase survival and prevent secondary morbidity. Multidisciplinary healthcare is necessary to improve healthcare for CDH patients. Absence of international therapy guidelines, lack of evidence of many therapeutic modalities and the relative low number of CDH patients calls for cooperation between centers with an expertise in the treatment of CDH patients. The international CDH Euro-Consortium is an example of such a collaborative network, which enhances exchange of knowledge, future research and development of treatment protocols.

Decreased surfactant phosphatidylcholine synthesis in neonates with congenital diaphragmatic hernia during extracorporeal membrane oxygenation

Purpose

Congenital diaphragmatic hernia (CDH) may result in severe respiratory insufficiency with a high morbidity. The role of a disturbed surfactant metabolism in the pathogenesis of CDH is unclear. We therefore studied endogenous surfactant metabolism in the most severe CDH patients who required extracorporeal membrane oxygenation (ECMO).

Methods

Eleven neonates with CDH who required ECMO and ten ventilated neonates without significant lung disease received a 24-h infusion of the stable isotope [U-¹³C] glucose. The ¹³C-incorporation into palmitic acid in surfactant phosphatidylcholine (PC) isolated from serial tracheal aspirates was measured. Mean PC concentration in epithelial lining fluid (ELF) was measured during the first 4 days of the study.

Results

Fractional surfactant PC synthesis was decreased in CDH-ECMO patients compared to controls (2.4 ± 0.33 vs. 8.0 ± 2.4%/day, p = 0.04). The control group had a higher maximal enrichment (0.18 ± 0.03 vs. 0.09 ± 0.02 APE, p = 0.04) and reached this maximal enrichment earlier (46.7 ± 3.0 vs. 69.4 ± 6.6 h, p = 0.004) compared to the CDH-ECMO group, which reflects higher and faster precursor incorporation in the control group. Surfactant PC concentration in ELF was similar in both groups.

Conclusion

These results show that CDH patients who require ECMO have a decreased surfactant PC synthesis, which may be part of the pathogenesis of severe pulmonary insufficiency and has a negative impact on weaning from ECMO.

Pulmonary surfactant kinetics of the newborn infant: novel insights from studies with stable isotopes

Deficiency or dysfunction of the pulmonary surfactant plays a critical role in the pathogenesis of respiratory diseases of the newborn. After a short review of the pulmonary surfactant, including its role in selected neonatal respiratory conditions, we describe a series of studies conducted by applying two recently developed methods to measure surfactant kinetics. In the first set of studies, namely 'endogenous studies', which used stable isotope-labeled intravenous surfactant precursors, we have shown the feasibility of measuring surfactant synthesis and kinetics in infants using several metabolic precursors, including plasma glucose, plasma fatty acids and body water. In the second set of studies, namely 'exogenous studies', which used a stable isotope-labeled phosphatidylcholine (PC) tracer given endotracheally, we estimated the surfactant disaturated phosphatidylcholine (DSPC) pool size and half-life. The major findings of our studies are presented here and can be summarized as follows: (a) the de novo synthesis and turnover rates of the surfactant (DSPC) in preterm infants with respiratory distress syndrome (RDS) are very low with either precursor; (b) in preterm infants with RDS, pool size is very small and half-life much longer than what has been reported in animal studies; (c) patients recovering from RDS who required higher continuous positive airway pressure pressure after extubation or reintubation have a lower level of intrapulmonary surfactant than those who did well after extubation; (d) term newborn infants with pneumonia have greatly accelerated surfactant catabolism; and (e) infants with uncomplicated congenital diaphragmatic hernia (CDH) and on conventional mechanical ventilation have normal surfactant synthesis, but those requiring extracorporeal membrane oxygenated (ECMO) do not. Information obtained from these studies in infants will help to better tailor exogenous surfactant treatment in neonatal lung diseases.

Ventilation and spontaneous breathing at birth of infants with congenital diaphragmatic hernia

OBJECTIVE

To describe the interaction of spontaneous breaths, manual ventilation, and tidal volumes (V(T)) during stabilization of infants with congenital diaphragmatic hernia (CDH) in the delivery room.

STUDY DESIGN

We studied infants with CDH receiving respiratory support at birth. Airway pressure, flow, and volume were measured, and each breath or inflation was analyzed. Each V(T) was classified as a manual inflation, a spontaneous breath, or a spontaneous breath coinciding with manual inflation on the basis of the timing of the pressure and flow waves.

RESULTS

Twelve infants had 2957 breaths suitable for analysis, with spontaneous breathing in 11 infants (92%). The mean (+/-SD) proportion of manual inflations was 41% (+/-24%), spontaneous breaths 43% (+/-25%), spontaneous but coinciding with manual inflation 16% (+/-12%). V(T) was significantly different for spontaneous breaths (3.8 +/- 1.9 mL/kg), spontaneous breaths coinciding with manual inflation (4.7 +/- 2.5 mL/kg), and manual inflations alone (2.6 +/- 1.6 mL/kg).

CONCLUSIONS

Most infants with CDH breathed spontaneously, and manual ventilation was mostly asynchronous. We observed large differences in tidal volumes between spontaneous breaths, manual inflations, or where these coincided, with manual inflations having the lowest V(T). Monitoring the respiratory pattern of these infants could improve respiratory support.

The long-term follow-up of patients with a congenital diaphragmatic hernia: a broad spectrum of morbidity

Congenital diaphragmatic hernia (CDH) is a life-threatening anomaly with a mortality rate of approximately 40-50%, depending on case selection. It has been suggested that new therapeutic modalities such as nitric oxide (NO), high frequency oxygenation (HFO) and extracorporal membrane oxygenation (ECMO) might decrease mortality associated with pulmonary hypertension and the sequelae of artificial ventilation. When these new therapies indeed prove to be beneficial, a larger number of children with severe forms of CDH might survive, resulting in an increase of CDH-associated complications and/or consequences. In follow-up studies of infants born with CDH, many complications including pulmonary damage, cardiovascular disease, gastro-intestinal disease, failure to thrive, neurocognitive defects and musculoskeletal abnormalities have been described. Long-term pulmonary morbidity in CDH consists of obstructive and restrictive lung function impairments due to altered lung structure and prolonged ventilatory support. CDH has also been associated with persistent pulmonary vascular abnormalities, resulting in pulmonary hypertension in the neonatal period. Long-term consequences of pulmonary hypertension are unknown. Gastro-esophageal reflux disease (GERD) is also an important contributor to overall morbidity, although the underlying mechanism has not been fully understood yet. In adult CDH survivors incidence of esophagitis is high and even Barrett's esophagus may ensue. Yet, in many CDH patients a clinical history compatible with GERD seems to be lacking, which may result in missing patients with pathologic reflux disease. Prolonged unrecognized GERD may eventually result in failure to thrive. This has been found in many young CDH patients, which may also be caused by insufficient intake due to oral aversion and increased caloric requirements due to pulmonary morbidity. Neurological outcome is determined by an increased risk of perinatal and neonatal hypoxemia in the first days of life of CDH patients. In patients treated with ECMO, the incidence of neurological deficits is even higher, probably reflecting more severe hypoxemia and the risk of ECMO associated complications. Many studies have addressed the substantial impact of the health problems described above, on the overall well-being of CDH patients, but most of them concentrate on the first years after repair and only a few studies focus on the health-related quality of life in CDH patients. Considering the scattered data indicating substantial morbidity in long-term survivors of CDH, follow-up studies that systematically assess long-term sequelae are mandatory. Based on such studies a more focused approach for routine follow-up programs may be established.

Prenatal prediction of neonatal morbidity in survivors with congenital diaphragmatic hernia: a multicenter study

OBJECTIVES

To investigate the value of the observed to expected fetal lung area to head circumference ratio (o/e LHR) and liver position in the prediction of neonatal morbidity in survivors with congenital diaphragmatic hernia (CDH).

METHODS

Neonatal morbidity was recorded in 100 consecutive cases with isolated CDH diagnosed in fetal medicine units, which were expectantly managed in the prenatal period, were delivered after 30 weeks and survived until discharge from hospital. Regression analysis was used to identify the significant predictors of morbidity, including prenatal and immediate neonatal findings.

RESULTS

The o/e LHR provided significant prediction of the need for prosthetic patch repair, duration of assisted ventilation, need for supplemental oxygen at 28 days, and incidence of feeding problems. An additional independent prenatal predictor of the need for patch repair was the presence of fetal liver in the chest.

CONCLUSIONS

In isolated CDH the prenatally assessed size of the contralateral lung is a significant predictor of the need for prosthetic patch repair, the functional consequences of impaired lung development and occurrence of feeding problems.

The lung-to-thorax transverse area ratio at term and near term correlates with survival in isolated congenital diaphragmatic hernia

OBJECTIVE

The purpose of this study was to determine how well liver position, the lung area-to-head circumference (L/H) ratio, and the lung-to-thorax transverse area (L/T) ratio predicted the need for extra-corporeal membrane oxygenation (ECMO) and survival in fetuses with isolated congenital diaphragmatic hernia (CDH).

METHODS

Antenatal records of 25 fetuses with isolated left-sided CDH who were born by cesarean delivery under fetal stabilization at this institution were reviewed. The latest determinations of the L/H and L/T ratios before birth (between 34 and 38 weeks' gestation) were compared on the basis of the cutoff points for mortality: less than 1.0 versus 1.0 or greater for the L/H ratio and 0.08 or less versus greater than 0.08 for the L/T ratio. Outcome measures assessed were survival (discharge to home) and the need for ECMO.

RESULTS

Overall survival was 64% (16/25). Postnatal survival in fetuses with an L/T ratio of 0.08 or less was statistically lower than in those with an L/T ratio of greater than 0.08 (33% versus 81%; P = .0308). The percentage requiring ECMO in the group with an L/T ratio of 0.08 or less was also higher than that of the group with an L/T ratio of greater than 0.08, but the difference was not statistically significant (67% versus 25%; P = .0872). Neither the L/H ratio nor herniation of the fetal liver into the chest affected survival or the need for ECMO.

CONCLUSIONS

In fetuses with isolated CDH at term or near term, the L/T ratio may be a better predictor of outcome than the L/H ratio or liver herniation.