Antenatal and postnatal lung and vascular anatomic and functional studies in congenital diaphragmatic hernia: implications for clinical management

The cardiopulmonary benefits of physiologically based cord clamping persist for at least 8 hours in lambs with a diaphragmatic hernia

Introduction

Infants with congenital diaphragmatic hernia can suffer severe respiratory insufficiency and pulmonary hypertension after birth. Aerating the lungs before removing placental support (physiologically based cord clamping, PBCC) increases pulmonary blood flow (PBF) and reduces pulmonary vascular resistance (PVR) in lambs with a diaphragmatic hernia (DH). We hypothesized that these benefits of PBCC persist for at least 8 h after birth.

Methods

At ∼138 days of gestation age (dGA), 21 lambs with a surgically induced left-sided DH (∼86 dGA) were delivered via cesarean section. The umbilical cord was clamped either before ventilation onset (immediate cord clamping, ICC, n = 9) or after achieving a tidal volume of 4 ml/kg, with a maximum delay of 10 min (PBCC, n = 12). The lambs were ventilated for 8 h, initially with conventional mechanical ventilation, but were switched to high-frequency oscillatory ventilation after 30 min if required. Ventilatory parameters, cardiopulmonary physiology, and arterial blood gases were measured throughout the study.

Results

PBF increased after ventilation onset in both groups and was higher in the PBCC DH lambs than the ICC DH lambs at 8 h (5.2 ± 1.2 vs. 1.9 ± 0.3 ml/min/g; p < 0.05). Measured over the entire 8-h ventilation period, PBF was significantly greater (p = 0.003) and PVR was significantly lower (p = 0.0002) in the PBCC DH lambs compared to the ICC DH lambs. A high incidence of pneumothoraces in both the PBCC (58%) and ICC (55%) lambs contributed to a reduced sample size at 8 h (ICC n = 4 and PBCC n = 4).

Conclusion

Compared with ICC, PBCC increased PBF and reduced PVR in DH lambs and the effects were sustained for at least 8 h after ventilation onset.

Intact cord resuscitation in newborns with congenital diaphragmatic hernia: insights from a lamb model

Introduction

Congenital diaphragmatic hernia (CDH) is a rare condition characterized by pulmonary hypoplasia, vascular dystrophy, and pulmonary hypertension at birth. Validation of the lamb model as an accurate representation of human CDH is essential to translating research findings into clinical practice and understanding disease mechanisms. This article emphasizes the importance of validating the lamb model to study CDH pathogenesis and develop innovative therapeutics.

Material and methods

At 78 days of gestation, the fetal lamb's left forelimb was exposed through a midline laparotomy and hysterotomy, and a supra diaphragmatic thoracotomy was performed to allow the digestive organs to ascend into the thoracic cavity. At 138 ± 3 days of gestation, lambs were delivered via a cesarean section; then, with umbilical cord intact during 1 hour, the lambs were mechanically ventilated with gentle ventilation in a pressure-controlled mode for 2 h.

Results

CDH lambs exhibited a lower left lung-to-body weight ratio of 5.3 (2.03), p < 0.05, and right lung-to-body weight ratio of 8.2 (3.1), p < 0.05. They reached lower Vt/kg (tidal volume per kg) during the course of the resuscitation period with 1.2 (0.7) ml/kg at 10 min and 3 (1.65) ml/kg at 60 min (p < 0.05). Compliance of the respiratory system was lower in CDH lambs with 0.5 (0.3) ml/cmH2O at 60 min (p < 0.05) and 0.9 (0.26) ml/cmH2O at 120 min (p < 0.05). Differences between pre- and postductal SpO2 were higher with 15.1% (21.4%) at 20 min and 6.7% (14.5%) at 80 min (p < 0.05). CDH lambs had lower differences between inspired and expired oxygen fractions with 4.55% (6.84%) at 20 min and 6.72% (8.57%) at 60 min (p < 0.05). CDH lamb had lower left ventricle [2.73 (0.5) g/kg, p < 0.05] and lower right ventricle [0.69 (0.8), p < 0.05] to left ventricle ratio.

Discussion

CDH lambs had significantly lower tidal volume than control lambs due to lower compliance of the respiratory system and higher airway resistance. These respiratory changes are characteristic of CDH infants and are associated with higher mortality rates. CDH lambs also exhibited pulmonary hypertension, pulmonary hypoplasia, and left ventricle hypoplasia, consistent with observations in human newborns. To conclude, our lamb model successfully provides a reliable representation of CDH and can be used to study its pathophysiology and potential interventions.

Perioperative Improvement in Pulmonary Function in Infants with Congenital Diaphragmatic Hernia

OBJECTIVE

The objective of this study was to compare serial changes in pulmonary function in contemporary infants with congenital diaphragmatic hernia managed with a gentle ventilation approach.

STUDY DESIGN

Observational cohort, single-center study of infants ≥35^0/7 weeks gestation at delivery with congenital diaphragmatic hernia. Functional residual capacity (FRC), passive respiratory compliance, and passive respiratory resistance were measured presurgical and postsurgical repair and within 2 weeks of discharge. A 1-way analysis of variance for repeated measures was used to evaluate the change in FRC, passive respiratory compliance, and passive respiratory resistance over these repeated measures.

RESULTS

Twenty-eight infants were included in the analysis with a mean gestational age of 38.3 weeks and birth weight of 3139 g. We found a significant increase in FRC across the 3 time points (mean in mL/kg [SD]: 10.9 [3.6] to 18.5 [5.2] to 24.2 [4.4]; P < .0001). There was also a significant increase in passive respiratory compliance and decrease in passive respiratory resistance. In contrast to a previous report, there were survivors in the current cohort with a preoperative FRC of <9 mL/kg. The mean FRC measured at discharge was in the range considered within normal limits. Sixteen infants had prenatal measurements of the lung-to-head ratio, but there was no relationship between the lung-to-head ratio and preoperative or postoperative FRC measurements.

CONCLUSIONS

Infants with congenital diaphragmatic hernia demonstrate significant increases in FRC and improvements in respiratory mechanics measured preoperatively and postoperatively and at discharge. We speculate these improvements are due to the surgical resolution of the mechanical obstruction to lung recruitment and that after achieving preoperative stability, repair should not be delayed given these demonstrable postoperative improvements.

Effect of prenatal diaphragmatic hernia on pulmonary arterial morphology

Congenital diaphragmatic hernia (CDH) is a major cause of severe lung hypoplasia and pulmonary hypertension in the newborn. While the pulmonary hypertension is thought to result from abnormal vascular development and arterial vasoreactivity, the anatomical changes in vascular development are unclear. We have examined the 3D structure of the pulmonary arterial tree in rabbits with a surgically induced diaphragmatic hernia (DH). Fetal rabbits (n = 6) had a left-sided DH created at gestational day 23 (GD23), delivered at GD30, and briefly ventilated; sham-operated litter mates (n = 5) acted as controls. At postmortem the pulmonary arteries were filled with a radio-opaque resin before the lungs were scanned using computed tomography (CT). The 3D reconstructed images were analyzed based on vascular branching hierarchy using the software Avizo 2020.2. DH significantly reduced median number of arteries (2,579 (8440) versus 576 (442), p = .017), artery numbers per arterial generation, mean total arterial volume (43.5 ± 8.4 vs. 19.9 ± 3.1 μl, p = .020) and mean total arterial cross-sectional area (82.5 ± 2.3 vs. 28.2 ± 6.2 mm2 , p =.036). Mean arterial radius was increased in DH kittens between the eighth and sixth branching generation and mean arterial length between the sixth and 28th branching generation. A DH in kittens resulted in threefold reduction in pulmonary arterial cross-sectional area, primarily due to reduced arterial branching. Thus, the reduction in arterial cross-sectional area could be a major contributor to pulmonary hypertension infants with CDH.

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

INTRODUCTION

Pulmonary hypertension is a major determinant of postnatal survival in infants with a congenital diaphragmatic hernia (CDH). The current care during the perinatal stabilisation period in these infants might contribute to the development of pulmonary hypertension after birth-in particular umbilical cord clamping before lung aeration. An ovine model of diaphragmatic hernia demonstrated that cord clamping after lung aeration, called physiological-based cord clamping (PBCC), avoided the initial high pressures in the lung vasculature while maintaining adequate blood flow, thereby avoiding vascular remodelling and aggravation of pulmonary hypertension. We aim to investigate if the implementation of PBCC in the perinatal stabilisation period of infants born with a CDH could reduce the incidence of pulmonary hypertension in the first 24 hours after birth.

METHODS AND ANALYSIS

We will perform a multicentre, randomised controlled trial in infants with an isolated left-sided CDH, born at ≥35.0 weeks. Before birth, infants will be randomised to either PBCC or immediate cord clamping, stratified by treatment centre and severity of pulmonary hypoplasia on antenatal ultrasound. PBCC will be performed using a purpose-built resuscitation trolley. Cord clamping will be performed when the infant is considered respiratory stable, defined as a heart rate >100 bpm, preductal oxygen saturation >85%, while using a fraction of inspired oxygen of <0.5. The primary outcome is pulmonary hypertension diagnosed in the first 24 hours after birth, based on clinical and echocardiographic parameters. Secondary outcomes include neonatal as well as maternal outcomes.

ETHICS AND DISSEMINATION

Central ethical approval was obtained from the Medical Ethical Committee of the Erasmus MC, Rotterdam, The Netherlands (METC 2019-0414). Local ethical approval will be obtained by submitting the protocol to the regulatory bodies and local institutional review boards.

TRIAL REGISTRATION NUMBER

NCT04373902.

Magnetic Resonance Imaging Assessment of Pulmonary Vascularity in Infants with Congenital Diaphragmatic Hernia: A Novel Tool for Direct Assessment of Severity of Pulmonary Hypertension and Hypoplasia

OBJECTIVES

To assess the feasibility of magnetic resonance imaging (MRI) for postnatal assessment of pulmonary vascularity in infants with congenital diaphragmatic hernia (CDH).

STUDY DESIGN

Infants with prenatally diagnosed CDH (n = 24) received postnatal pulmonary MRI. Infants with nonpulmonary birth defects served as controls (n = 5). Semiautomatic segmentation was performed to obtain total vascular volume using time of flight images to assess vascularity.

RESULTS

Average vascular density (vascular volume/lung volume) in control infants was 0.23 ± 0.06 mm³/mm³ compared with 0.18 ± 0.06 mm³/mm³ in infants with CDH is (P = .09). When stratified further based on CDH severity, the difference between control infants and moderate CDH group was statistically significant. (0.23 mm³/mm³ vs 0.15 mm³/mm³, P = .01). Ipsilateral vascular density on MRI in infants with CDH significantly correlated with the prenatal pulmonary hypertensive index (P = .0004, Spearman R = +0.87) and with number of days on mechanical ventilation (P = .04, Spearman R = -0.44), total days on inhaled nitric oxide (P = .02, Spearman R = -0.47), use of epoprostenol for acute pulmonary hypertension (PH) (0.14 mm³/mm³ vs 0.20 mm³/mm³, P = .005), and use of sildenafil for chronic PH (0.15 mm³/mm³ vs 0.19 mm³/mm³, P = .03).

CONCLUSIONS

Our results suggest that postnatal pulmonary vascularity assessed by MRI strongly correlates with prenatal and postnatal markers of PH severity and that pulmonary vascularity may serve as a direct measure of pulmonary vascular hypoplasia in infants with CDH.

Physiologically based cord clamping improves cardiopulmonary haemodynamics in lambs with a diaphragmatic hernia

OBJECTIVE

Lung hypoplasia associated with congenital diaphragmatic hernia (CDH) results in respiratory insufficiency and pulmonary hypertension after birth. We have investigated whether aerating the lung before removing placental support (physiologically based cord clamping (PBCC)), improves the cardiopulmonary transition in lambs with a CDH.

METHODS

At ≈138 days of gestational age, 17 lambs with surgically induced left-sided diaphragmatic hernia (≈d80) were delivered via caesarean section. The umbilical cord was clamped either immediately prior to ventilation onset (immediate cord clamping (ICC); n=6) or after achieving a target tidal volume of 4 mL/kg, with a maximum delay of 10 min (PBCC; n=11). Lambs were ventilated for 120 min and physiological changes recorded.

RESULTS

Pulmonary blood flow (PBF) increased following ventilation onset in both groups, but was 19-fold greater in PBCC compared with ICC lambs at cord clamping (19±6.3 vs 1.0±0.5 mL/min/kg, p<0.001). Cerebral tissue oxygenation was higher in PBCC than ICC lambs during the first 10 min after cord clamping (59%±4% vs 30%±5%, p<0.001). PBF was threefold higher (23±4 vs 8±2 mL/min/kg, p=0.01) and pulmonary vascular resistance (PVR) was threefold lower (0.6±0.1 vs 2.2±0.6 mm Hg/(mL/min), p<0.001) in PBCC lambs compared with ICC lambs at 120 min after ventilation onset.

CONCLUSIONS

Compared with ICC, PBCC prevented the severe asphyxia immediately after birth and resulted in a higher PBF due to a lower PVR, which persisted for at least 120 min after birth in CDH lambs.

Effects of tracheal occlusion on the neonatal cardiopulmonary transition in an ovine model of diaphragmatic hernia

OBJECTIVE

Fetoscopic endoluminal tracheal occlusion (FETO) aims to reverse pulmonary hypoplasia associated with congenital diaphragmatic hernia (CDH) and mitigate the associated respiratory insufficiency and pulmonary hypertension after birth. We aimed to determine whether FETO improves the cardiopulmonary transition at birth in an ovine model of CDH.

METHODS

In 12 ovine fetuses with surgically induced diaphragmatic hernia (DH; 80 dGA), an endotracheal balloon was placed tracheoscopically at ≈110 dGA and removed at ≈131 dGA (DH+FETO), while 10 were left untreated (DH). At ≈138 dGA, all lambs (survival at delivery: 67% [DH+FETO], 70% [DH]) were delivered via caesarean section and ventilated for 2 hours. Physiological and ventilation parameters were continuously recorded, and arterial blood-gas values were measured.

RESULTS

Compared with DH, DH+FETO lambs had increased wet lung-to-body-weight ratio (0.031±0.004 vs 0.016±0.002) and dynamic lung compliance (0.7±0.1 vs 0.4±0.1 mL/cmH₂O). Pulmonary vascular resistance was lower in DH+FETO lambs (0.44±0.11 vs 1.06±0.17 mm Hg/[mL/min]). However, after correction for lung weight, pulmonary blood flow was not significantly different between the groups (4.19±0.57 vs 4.05±0.60 mL/min/g). Alveolar-arterial difference in oxygen tension was not significantly different between DH+FETO and DH (402±41mm Hg vs 401±45 mm Hg).

CONCLUSIONS

FETO accelerated lung growth in fetuses with CDH and improved neonatal respiratory function during the cardiopulmonary transition at birth. However, despite improved lung compliance and reduced pulmonary vascular resistance, there were less pronounced benefits for gas exchange during the first 2 hours of life.

Neonatal cardiopulmonary transition in an ovine model of congenital diaphragmatic hernia

OBJECTIVE

Infants with a congenital diaphragmatic hernia (CDH) are at high risk of developing pulmonary hypertension after birth, but little is known of their physiological transition at birth. We aimed to characterise the changes in cardiopulmonary physiology during the neonatal transition in an ovine model of CDH.

METHODS

A diaphragmatic hernia (DH) was surgically created at 80 days of gestational age (dGA) in 10 fetuses, whereas controls underwent sham surgery (n=6). At 138 dGA, lambs were delivered via caesarean section and ventilated for 2 hours. Physiological and ventilation parameters were continuously recorded, and arterial blood gas values were measured.

RESULTS

DH lambs had lower wet lung-to-body-weight ratio (0.016±0.002vs0.033±0.004), reduced dynamic lung compliance (0.4±0.1mL/cmH₂O vs1.2±0.1 mL/cmH₂O) and reduced arterial pH (7.11±0.05vs7.26±0.05), compared with controls. While measured pulmonary blood flow (PBF) was lower in DH lambs, after correction for lung weight, PBF was not different between groups (4.05±0.60mL/min/gvs4.29±0.57 mL/min/g). Cerebral tissue oxygen saturation was lower in DH compared with control lambs (55.7±3.5vs67.7%±3.9%).

CONCLUSIONS

Immediately after birth, DH lambs have small, non-compliant lungs, respiratory acidosis and poor cerebral oxygenation that reflects the clinical phenotype of human CDH. PBF (indexed to lung weight) was similar in DH and control lambs, suggesting that the reduction in PBF associated with CDH is proportional to the degree of lung hypoplasia during the neonatal cardiopulmonary transition.

Antenatal sildenafil treatment improves neonatal pulmonary hemodynamics and gas exchange in lambs with diaphragmatic hernia

OBJECTIVES

Infants with congenital diaphragmatic hernia (CDH) are predisposed to pulmonary hypertension after birth, owing to lung hypoplasia that impairs fetal pulmonary vascular development. Antenatal sildenafil treatment attenuates abnormal pulmonary vascular and alveolar development in rabbit and rodent CDH models, but whether this translates to functional improvements after birth remains unknown. We aimed to evaluate the effect of antenatal sildenafil on neonatal pulmonary hemodynamics and lung function in lambs with diaphragmatic hernia (DH).

METHODS

DH was surgically induced at approximately 80 days' gestation in 16 lamb fetuses (term in lambs is approximately 147 days). From 105 days' gestation, ewes received either sildenafil (0.21 mg/kg/h intravenously) or saline infusion until delivery (n = 8 fetuses in each group). At approximately 138 days' gestation, all lambs were instrumented and then delivered via Cesarean section. The lambs were ventilated for 120 min with continuous recording of physiological (pulmonary and carotid artery blood flow and pressure; cerebral oxygenation) and ventilatory parameters, and regular assessment of arterial blood gas tensions. Only lambs that survived until delivery and with a confirmed diaphragmatic defect at postmortem examination were included in the analysis; these comprised six DH-sildenafil lambs and six DH-saline control lambs.

RESULTS

Lung-to-body-weight ratio (0.016 ± 0.001 vs 0.013 ± 0.001; P = 0.06) and dynamic lung compliance (0.8 ± 0.2 vs 0.7 ± 0.2 mL/cmH₂ O; P = 0.72) were similar in DH-sildenafil lambs and controls. Pulmonary vascular resistance decreased following lung aeration to a greater degree in DH-sildenafil lambs, and was 4-fold lower by 120 min after cord clamping than in controls (0.6 ± 0.1 vs 2.2 ± 0.6 mmHg/(mL/min); P = 0.002). Pulmonary arterial pressure was also lower (46 ± 2 vs 59 ± 2 mmHg; P = 0.048) and pulmonary blood flow higher (25 ± 3 vs 8 ± 2 mL/min/kg; P = 0.02) in DH-sildenafil than in DH-saline lambs at 120 min. Throughout the 120-min ventilation period, the partial pressure of arterial carbon dioxide tended to be lower in DH-sildenafil lambs than in controls (63 ± 8 vs 87 ± 8 mmHg; P = 0.057), and there was no significant difference in partial pressure of arterial oxygen between the two groups.

CONCLUSIONS

Sustained maternal antenatal sildenafil infusion reduced pulmonary arterial pressure and increased pulmonary blood flow in DH lambs for the first 120 min after birth. These findings of improved pulmonary vascular function are consistent with improved pulmonary vascular structure seen in two previous animal models. The data support the rationale for a clinical trial investigating the effect of antenatal sildenafil in reducing the risk of neonatal pulmonary hypertension in infants with CDH. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Pulmonary Hypertension in Patients with Congenital Diaphragmatic Hernia: Does Lung Size Matter?

PURPOSE

 The relationship between pulmonary hypoplasia and pulmonary arterial hypertension (PHTN) in patients with congenital diaphragmatic hernia (CDH) remains ill-defined. We hypothesized that prenatal estimates of lung size would directly correlate with PHTN severity.

METHODS

 Infants with isolated CDH (born 2004-2015) at a single institution were included. Estimates of lung size included observed-to-expected LHR (o:eLHR) and %-predicted lung volumes (PPLV = observed/predicted volumes). The primary outcome was severity of PHTN (grade 0-3) on echocardiography performed between day of life 3 and 30.

RESULTS

 Among 62 patients included, there was 32% mortality and 65% ECMO utilization. PPLV (odds ratio [OR] = 0.94 per 1 grade in PHTN severity, 95% confidence interval [CI] = 0.89-0.98, p < 0.01) and o:eLHR (OR = 0.97, 95% CI = 0.94-0.99, p < 0.01) were significantly associated with PHTN grade. Among patients on ECMO, PPLV (OR = 0.92, 95% CI = 0.84-0.99, p = 0.03) and o:eLHR (OR = 0.95, 95% CI = 0.92-0.99, p = 0.01) were more strongly associated with PHTN grade. PPLV and o:eLHR were significantly associated with the use of inhaled nitric oxide (iNO) (OR = 0.90, 95% CI = 0.83-0.98, p = 0.01 and OR = 0.94, 95% CI = 0.91-0.98, p < 0.01, respectively) and epoprostenol (OR = 0.91, 95% CI = 0.84-0.99, p = 0.02 and OR = 0.93, 95% CI = 0.89-0.98, p < 0.01, respectively).

CONCLUSION

 Among infants with isolated CDH, PPLV, and o:eLHR were significantly associated with PHTN severity, especially among patients requiring ECMO. Prenatal lung size may help predict postnatal PHTN and associated therapies.

Repair of congenital diaphragmatic hernia during extracorporeal life support: experience with six neonates

BACKGROUND

The management of congenital diaphragmatic hernia (CDH) in neonates has evolved considerably over the last three decades. Initial stabilization followed by surgical repair is the current standard of care. A subset fails to achieve adequate oxygenation with medical management, including the use of high frequency oscillation and inhaled nitric oxide. The mortality in this group exceeds 80% without additional management strategies. Extracorporeal life support (ECLS) is a well-established modality for managing these neonates with CDH and has been shown to improve early survival in selected cases.

METHODS

This is a retrospective analysis of six neonates with CDH who underwent repair during ECLS between September 2011 and November 2014.

RESULTS

Of 24 admissions with CDH, there were six neonates (25%) who required ECLS. All the six had CDH repair during ECLS. There were no intra-operative bleeding complications. There were no clotting complications related to stopping heparin during CDH repair. There was one hospital death. Five neonates were weaned from ECLS and discharged home.

CONCLUSIONS

Data from our small cohort of patients illustrate that early survival is possible in extremely compromised neonates who otherwise would have died without ECLS. Our experience demonstrates that CDH repair can safely be performed during ECLS. Use of ECLS, early repair during ECLS, lung protective ventilation strategies and aggressive management of pulmonary hypertension were associated with good early survival. ECLS should be considered as an integral part of therapeutic armamentarium for CDH in neonates.

Fetal ultrasound markers of severity predict resolution of pulmonary hypertension in congenital diaphragmatic hernia

OBJECTIVE

Congenital diaphragmatic hernia (CDH) results in morbidity and death from lung hypoplasia and persistent pulmonary hypertension (PH). We sought to define the relationship between fetal ultrasound markers of severity in CDH and the time to resolution of neonatal PH.

STUDY DESIGN

We conducted a retrospective study of fetuses with an antenatal ultrasound scan and left-sided CDH cared for at the University of California San Francisco (2002-2012). Fetal liver position was classified on ultrasound scan as abdominal (entire liver within the abdomen) or thoracic (any portion of the liver within the thorax). Fetal stomach position was classified from least to most aberrant: abdominal, anterior left chest, mid-posterior left chest, or retrocardiac (right chest). Lung-to-head ratio (LHR) was determined from available scans at 20-29 weeks of gestational age (GA). Routine neonatal echocardiograms were performed weekly for up to 6 weeks or until PH resolved or until discharge. PH was assessed by echocardiogram with the use of a hierarchy of ductus arteriosus level shunt, interventricular septal position, and tricuspid regurgitant jet velocity. Days to PH-free survival was defined as the age at which pulmonary artery pressure was estimated to be <2/3 systemic blood pressure. Cox proportional hazards models adjusted for GA at birth, era of birth, fetal surgery, and GA at ultrasound scan (LHR model only), with censoring at 100 days.

RESULTS

Of 118 patients, the following fetal markers were available: LHR (n = 53), liver position (n = 112), and stomach position (n = 80). Fewer infants experienced resolved PH if they had LHR <1 (P = .006), thoracic liver position (P = .001), or more aberrant stomach position (P < .001). There was also a decreased rate of resolution of PH in infants with LHR <1 (hazard ratio, 0.30; P = .007), thoracic liver position (hazard ratio, 0.38; P < .001), and more aberrant stomach position (hazard ratios, 0.28 [P = .002]; 0.1 [P < .001]; and 0.07 [P < .001]).

CONCLUSION

Fetal ultrasound markers of CDH severity are predictive not only of death but also of significant morbidity. LHR <1, thoracic liver, and aberrant stomach position are associated with delayed time to resolution of PH in infants with CDH and may be used to identify fetuses at high risk of persistent PH.

Plasma vascular endothelial growth factor A and placental growth factor: novel biomarkers of pulmonary hypertension in congenital diaphragmatic hernia

Pulmonary hypertension (PH) due to abnormal pulmonary vascular development is an important determinant of illness severity in congenital diaphragmatic hernia (CDH). Vascular endothelial growth factor A (VEGFA) and placental growth factor (PLGF) may be important mediators of pulmonary vascular development in health and disease. This prospective study investigated the relationship between plasma VEGFA and PLGF and measures of pulmonary artery pressure, oxygenation, and cardiac function in CDH. A cohort of 10 infants with CDH consecutively admitted to a surgical neonatal intensive care unit (NICU) was recruited. Eighty serial plasma samples were obtained and analyzed by multiplex immunoassay to quantify VEGFA and PLGF. Concurrent assessment of pulmonary artery pressure (PAP) and cardiac function were made by echocardiography. Plasma VEGFA was higher and PLGF was lower in CDH compared with existing normative data. Combined plasma VEGFA:PLGF ratio correlated positively with measures of PAP, diastolic ventricular dysfunction, and oxygenation index. Nonsurvivors had higher VEGFA:PLGF ratio than survivors at days 3–4 of life and in the second week of life. These findings suggest that increased plasma VEGFA and reduced PLGF correlate with clinical severity of pulmonary vascular disease and may be associated with adverse outcome in CDH. This potential role for combined plasma VEGFA and PLGF in CDH as disease biomarkers, pathogenic mediators, and therapeutic targets merits further investigation.

Airway and vascular maturation stimulated by tracheal occlusion do not correlate in the rabbit model of diaphragmatic hernia

BACKGROUND

In animal models of congenital diaphragmatic hernia (CDH), tracheal occlusion (TO) has induced maturation of both airway spaces and vascular structures. Airway and vascular response to TO are assumed to occur in parallel. This study aims to describe and measure the relationship between airway and vascular maturation induced by TO.

METHODS

A rabbit model of CDH on gestational day (GD) 23 and TO on GD 28 (term = GD 31) has been used. Two study groups have been defined: DH (diaphragmatic hernia) and TO (DH treated with TO). Animals were collected on GD 30 and blood flow data of the pulmonary artery (pulsatility index (PI) and fractional moving blood volume) were ultrasonographically measured. Lung morphometry consisted of measurements of radial alveolar count (RAC) and arterial muscular thickness.

RESULTS

Animals in the DH group (n = 9) had the worst hemodynamic parameters; their lungs were hypoplastic and had the thickest arterial muscular layer. Animals in the TO group (n = 10) had all these effects reversed. There were no correlations among hemodynamic, airway, and vascular parameters, except for RAC and PI (r = -0.528, P = 0.043).

CONCLUSION

Airway and vascular maturation after TO appear to be uncorrelated effects. TO could trigger several pathways that separately regulate airway and vascular responses.

First 24-h SNAP-II score and highest PaCO2 predict the need for ECMO in congenital diaphragmatic hernia

BACKGROUND/PURPOSE

Early clinical predictors for the use of ECMO in patients with congenital diaphragmatic hernia (CDH) are lacking. We sought to evaluate the first 24-h SNAP-II score and highest PaCO2 as predictors of ECMO support and in-hospital mortality in neonates with CDH.

METHODS

Retrospective review of 47 consecutive neonates with CDH admitted to our institution from January 2007 to December 2010 was performed. Covariates of ECMO use including SNAP-II score and highest PaCO2 within the first 24 h of NICU admission were evaluated.

RESULTS

Of the 47 infants in this study, 24 patients were supported with ECMO. The ECMO group had a higher incidence of pulmonary hypertension, higher PaCO2, and higher 24-h SNAP-II scores. Only the SNAP-II score and not highest PaCO2 predicted mortality following multivariate adjustment.

CONCLUSIONS

The first 24-h SNAP-II score and highest PaCO2 may provide some prognostic value in identifying neonates who undergo ECMO support; however neither measure was independently associated with the use of therapy. Only the SNAP-II score was associated with in-hospital mortality following multivariate adjustment. Additional study is needed to validate these results in a larger data set.

Development of the diaphragm -- a skeletal muscle essential for mammalian respiration

The mammalian diaphragm muscle is essential for respiration, and thus is one of the most critical skeletal muscles in the human body. Defects in diaphragm development leading to congenital diaphragmatic hernias (CDH) are common birth defects and result in severe morbidity or mortality. Given its functional importance and the frequency of congenital defects, an understanding of diaphragm development, both normally and during herniation, is important. We review current knowledge of the embryological origins of the diaphragm, diaphragm development and morphogenesis, as well as the genetic and developmental aetiology of diaphragm birth defects.

Right- versus left-sided congenital diaphragmatic hernia: postnatal outcome at a specialized tertiary care center

OBJECTIVE

To systematically investigate the impact of the location of the defect in congenital diaphragmatic hernia on neonatal mortality and morbidity with a special focus on survival at discharge, extracorporeal membrane oxygenation requirement, and the development of chronic lung disease.

DESIGN

Retrospective tertiary care center study with a matched-pair analysis of all fetuses that were treated for congenital diaphragmatic hernia between 2004 and 2009.

SETTING

A specialized tertiary care center for fetuses with congenital diaphragmatic hernia.

PATIENTS

Complete sets of data were available for 106 patients with congenital diaphragmatic hernia. For 17 of 18 infants with right-sided congenital diaphragmatic hernia we were able to allocate infants with left-sided congenital diaphragmatic hernia with no relevant difference in previously described prognostic factors, such as pulmonary hypoplasia and liver herniation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

There was a strong trend toward better survival in infants with right-sided congenital diaphragmatic hernia than with left-sided congenital diaphragmatic hernia (94% vs. 70%; p = .07). More neonates with left-sided congenital diaphragmatic hernia died of severe pulmonary hypertension despite extracorporeal membrane oxygenation. Fewer neonates with right-sided congenital diaphragmatic hernia died, yet higher degrees of pulmonary hypoplasia and oxygen requirement were observed despite extracorporeal membrane oxygenation.

CONCLUSIONS

In congenital diaphragmatic hernia, the location of the defect has a substantial impact on postnatal survival and the development of chronic lung disease. In left-sided congenital diaphragmatic hernia, pulmonary hypertension resistant to therapeutic management, including extracorporeal membrane oxygenation, is more common and is associated with a higher rate of neonatal demise. Right-sided congenital diaphragmatic hernia infants have an increased benefit from extracorporeal membrane oxygenation but the better survival entails a higher rate of chronic lung disease.

Expression of hypoxia-inducible factors, regulators, and target genes in congenital diaphragmatic hernia patients

Congenital diaphragmatic hernia (CDH) is associated with lung hypoplasia and pulmonary hypertension and has high morbidity and mortality rates. The cause and pathophysiology of CDH are not fully understood. However, impaired angiogenesis appears to play an important role in the pathophysiology of CDH. Therefore, we examined different components of an important pathway in angiogenesis: hypoxia-inducible factors (HIFs); HIF regulators von Hippel-Lindau (VHL) and prolyl 3-hydroxylase (PHD3); and HIF target genes vascular endothelial growth factor A ( VEGF-A ) and vascular endothelial growth factor receptor 2 ( VEGFR-2 ). Quantitative polymerase chain reaction of lung tissue showed a significantly decreased expression of VEGF-A mRNA in the alveolar stage of lung development in CDH patients compared with matched control patients. In the canalicular stage, no differences for VEGF-A were seen between the lungs of CDH patients and those of control patients. Other components of angiogenesis (VHL, HIF-1α, HIF-2α, HIF-3α, VEGFR-2 mRNA, PHD3 protein) that were analyzed showed no differences in expression between CDH and control patients, independent of the developmental stage. A lower expression of VEGF mRNA in CDH patients in the alveolar stage, possibly as a result of downregulation of HIF-2α might indicate a role for these factors in the pathophysiology of CDH.

Management of congenital diaphragmatic hernia

PURPOSE OF REVIEW

To evaluate the impact of recent research on the management of congenital diaphragmatic hernia in the light of new theories on embryological development, earlier antenatal diagnosis, fetal and postnatal interventions together with advances in perinatal intensive care.

RECENT FINDINGS

The year 2007 provided in excess of 200 publications that address various aspects of congenital diaphragmatic hernia. The genetic basis and the causes of pulmonary hypoplasia at the molecular level are slowly being unravelled. Fetal MRI of lung volume, lung-head ratio, liver position and size of diaphragmatic defect have all been evaluated as early predictors of outcome and with a view to prenatal counselling. The impact of fetal interventions such as fetal endoluminal tracheal occlusion, the mode of delivery, the surgical techniques and agents for treating pulmonary hypertension were evaluated. The influence of associated anomalies and therapeutic interventions on the outcome and quality of life of survivors continue to be appraised.

SUMMARY

Deferred surgery after stabilization with gentle ventilation and reversal of pulmonary hypertension remain the cornerstones of management. Optimal presurgery and postsurgery ventilatory settings remain unproven. Continued improvement in neonatal intensive care raises the bar against which any intervention such as fetal endoluminal tracheal occlusion and extracorporeal membrane oxygenation will be judged.