Prenatal assessment of pulmonary vasculature development in fetuses with congenital diaphragmatic hernia: A literature review

Pathophysiological studies have shown that pulmonary vascular development is impaired in fetuses with a congenital diaphragmatic hernia (CDH), leading to a simplified vascular tree and increased vascular resistance. Multiple studies have described prenatal ultrasound parameters for the assessment of the pulmonary vasculature, but none of these parameters are used in daily clinical practice. We provide a comprehensive review of the literature published between January 1990 and February 2022 describing these parameters, and aim to explain the clinical relevance of these parameters from what is known from pathophysiological studies. Prenatal detection of a smaller diameter of the contralateral (i.e. contralateral to the diaphragmatic defect) first branch of the pulmonary artery (PA), higher pulsatility indices (PI), higher peak early diastolic reverse flow values, and a lower vascularization index seem of added value for the prediction of survival and, to a lesser extent, morbidity. Integration within the routine evaluation is complicated by the lack of uniformity of the methods used. To address the main components of the pathophysiological changes, we recommend future prenatal studies in CDH with a focus on PI values, PA diameters and pulmonary vascular branching.

Organ-specific learning curves of sonographers performing first-trimester anatomical screening and impact of score-based evaluation on ultrasound image quality

INTRODUCTION

First-trimester anatomical screening (FTAS) by ultrasound has been introduced in many countries as screening for aneuploidies, but also as early screening for fetal structural abnormalities. While a lot of emphasis has been put on the detection rates of FTAS, little is known about the performance of quality control programs and the sonographers' learning curve for FTAS. The aims of the study were to evaluate the performance of a score-based quality control system for the FTAS and to assess the learning curves of sonographers by evaluating the images of the anatomical planes that were part of the FTAS protocol.

METHODS

Between 2012-2015, pregnant women opting for the combined test in the North-Netherlands were also invited to participate in a prospective cohort study extending the ultrasound investigation to include a first-trimester ultrasound performed according to a protocol. All anatomical planes included in the protocol were documented by pictures stored for each examination in logbooks. The logbooks of six sonographers were independently assessed by two fetal medicine experts. For each sonographer, logbooks of examination 25-50-75 and 100 plus four additional randomly selected logbooks were scored for correct visualization of 12 organ-system planes. A plane specific score of at least 70% was considered sufficient. The intra-class correlation coefficient (ICC), was used to measure inter-assessor agreement for the cut-off scores. Organ-specific learning curves were defined by single-cumulative sum (CUSUM) analysis.

RESULTS

Sixty-four logbooks were assessed. Mean duration of the scan was 22 ± 6 minutes and mean gestational age was 12+6 weeks. In total 57% of the logbooks graded as sufficient. Most sufficient scores were obtained for the fetal skull (88%) and brain (70%), while the lowest scores were for the face (29%) and spine (38%). Five sonographers showed a learning curve for the skull and the stomach, four for the brain and limbs, three for the bladder and kidneys, two for the diaphragm and abdominal wall and one for the heart and spine and none for the face and neck.

CONCLUSION

Learning curves for FTAS differ per organ system and per sonographer. Although score-based evaluation can validly assess image quality, more dynamic approaches may better reflect clinical performance.

Pulmonary hypertension in congenital diaphragmatic hernia: ANTENATAL PREDICTION AND IMPACT ON NEONATAL MORTALITY

OBJECTIVE

To determine the prevalence of pulmonary hypertension(PAH) in left-sided congenital diaphragmatic hernia(CDH); how we could predict it; and how PAH contributed to the model for mortality prediction.

STUDY DESIGN

Retrospective analysis in three European centers. The primary outcome was the presence of PAH on postnatal day(d)1,7, and at discharge. Studied predictors of PAH were: observed/expected-lung/head-ratio(o/e LHR), liver-herniation, FETO, and gestational age(GA) at delivery. The combined effect of pre-and postnatal variables on mortality was modeled by Cox regression.

RESULTS

Of the 197 neonates, 56(28.4%) died. At d1, 67.5%(133/197) had PAH and 61.9% (101/163) by d7. Overall, 6.4% (9/141) had PAH at discharge.At d1, o/eLHR(OR 0.96) and FETO(OR 2.99) independently correlated to PAH(AUC:0.74). At d7, PAH significantly correlated only with the use of FETO (OR 3.9;AUC:0.65). None were significant for PAH at discharge.Combining the occurrence of PAH with antenatal biomarkers improved mortality prediction(p=0.02), in a model including o/eLHR(HR:0.94), FETO(HR:0.35), liver herniation(HR:16.78), and PAH(HR:15.95).

CONCLUSIONS

Antenatal prediction of PAH was only moderate. The postnatal occurrence of PAH further increases the risk of death. Whereas this may be used to counsel parents in the postnatal period, our study demonstrates there is a need to find more accurate antenatal predictors for PAH. This article is protected by copyright. All rights reserved.

Intrapulmonary artery Doppler to predict mortality and morbidity in fetuses with mild or moderate left-sided congenital diaphragmatic hernia

OBJECTIVES

In fetuses with isolated left-sided congenital diaphragmatic hernia (LCDH), prenatal detection of severe pulmonary hypoplasia is important, as fetal therapy can improve survival. Cases with mild or moderate lung hypoplasia still carry a considerable risk of mortality and morbidity, but there has been less interest in the accurate prediction of outcome in these cases. In this study of fetuses with mild or moderate isolated LCDH, we aimed to investigate: (1) the association between intrapulmonary artery (IPA) Doppler findings and mortality at discharge; (2) whether adding IPA Doppler findings improves the prediction of mortality based on lung size and liver herniation; and (3) the association between IPA Doppler findings and early neonatal morbidity.

METHODS

This was a retrospective study of all consecutive fetuses assessed at the BCNatal and UZ Leuven hospitals between 2008 and 2020 with a prenatal diagnosis of isolated, non-severe LCDH, defined as observed-to-expected lung-to-head ratio (o/e-LHR) > 25%, that were managed expectantly during pregnancy followed by standardized neonatal management. An additional inclusion criterion was the availability of IPA Doppler measurements. The primary outcome was the association between IPA Doppler findings and mortality at discharge. Other predictors included o/e-LHR, liver herniation and gestational age at birth. Secondary outcomes were the association between IPA Doppler findings and the presence of pulmonary hypertension (PHT), need for supplemental oxygen at discharge and need for extracorporeal membrane oxygenation. IPA pulsatility index (PI) values were converted into Z-scores. Logistic regression analysis was performed to investigate the associations between predictor variables and outcome, and the best model was chosen based on the Nagelkerke R² .

RESULTS

Observations for 70 non-severe LCDH cases were available. Fifty-four (77%) fetuses survived until discharge. On logistic regression analysis, higher IPA-PI was associated with an increased risk of mortality (odds ratio (OR), 3.96 (95% CI, 1.62-9.70)), independently of o/e-LHR (OR, 0.87 (95% CI, 0.79-0.97)). An IPA-PI Z-score cut-off of 1.8 predicted mortality with a detection rate of 69% and specificity of 93%. Adding IPA-PI to o/e-LHR improved significantly the model's performance (Nagelkerke R² , 46% for o/e-LHR + IPA-PI vs 28% for o/e-LHR (P < 0.002)), with a detection rate of 81% at a 10% false-positive rate. IPA-PI was associated with PHT (OR, 2.20 (95% CI, 1.01-4.59)) and need for oxygen supplementation at discharge (OR, 1.90 (95% CI, 1.10-3.40)), independently of lung size.

CONCLUSIONS

In fetuses with mild or moderate LCDH, IPA-PI was associated with mortality and morbidity, independently of lung size. A model combining o/e-LHR with IPA-PI identified up to four in five cases that eventually died, despite being considered to have non-severe pulmonary hypoplasia. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Resuscitation Opportunities for Fellows of Very Low Birth Weight Infants in the Vermont Oxford Network

BACKGROUND

Neonatal-perinatal medicine (NPM) fellowship programs must provide adequate delivery room (DR) experience to ensure that physicians can independently provide neonatal resuscitation to very low birth weight (VLBW) infants. The availability of learning opportunities is unknown.

METHODS

The number of VLBW (≤1500 g) and extremely low birth weight (ELBW) (<1000 g) deliveries, uses of continuous positive airway pressure, intubation, chest compressions, and epinephrine over 3 years at accredited civilian NPM fellowship program delivery hospitals were determined from the Vermont Oxford Network from 2012 to 2017. Using Poisson distributions, we estimated the expected probabilities of fellows experiencing a given number of cases over 3 years at each program.

RESULTS

Of the 94 NPM fellowships, 86 programs with 115 delivery hospitals and 62 699 VLBW deliveries (28 703 ELBW) were included. During a 3-year fellowship, the mean number of deliveries per fellow ranged from 14 to 214 (median: 60) for VLBWs and 7 to 107 (median: 27) for ELBWs. One-half of fellows were expected to see ≤23 ELBW deliveries and 52 VLBW deliveries, 24 instances of continuous positive airway pressure, 23 intubations, 2 instances of chest compressions, and 1 treatment with epinephrine.

CONCLUSIONS

The number of opportunities available to fellows for managing VLBW and ELBW infants in the DR is highly variable among programs. Fellows' exposure to key, high-risk DR procedures such as cardiopulmonary resuscitation is low at all programs. Fellowship programs should track fellow exposure to neonatal resuscitations in the DR and integrate supplemental learning opportunities. Given the low numbers, the number of new and existing NPM programs should be considered.

Complementary Effect of Maternal Sildenafil and Fetal Tracheal Occlusion Improves Lung Development in the Rabbit Model of Congenital Diaphragmatic Hernia

OBJECTIVE

To evaluate the effect of combining antenatal sildenafil with fetal tracheal occlusion (TO) in fetal rabbits with surgically induced congenital diaphragmatic hernia (CDH).

BACKGROUND

Although antenatal sildenafil administration rescues vascular abnormalities in lungs of fetal rabbits with CDH, it only partially improves airway morphometry. We hypothesized that we could additionally stimulate lung growth by combining this medical treatment with fetal TO.

METHODS

CDH was created on gestational day (GD)23 (n=54). Does were randomized to receive either sildenafil 10 mg/kg/d or placebo by subcutaneous injection from GD24 to GD30. On GD28, fetuses were randomly assigned to TO or sham neck dissection. At term (GD30) fetuses were delivered, ventilated, and finally harvested for histological and molecular analyses. Unoperated littermates served as controls.

RESULTS

The lung-to-body-weight ratio was significantly reduced in sham-CDH fetuses either (1.2 ± 0.3% vs 2.3 ± 0.3% in controls, P=0.0003). Sildenafil had no effect on this parameter, while CDH fetuses undergoing TO had a lung-to-body-weight ratio comparable to that of controls (2.5 ± 0.8%, P<0.0001). Sildenafil alone induced an improvement in the mean terminal bronchiolar density (2.5 ± 0.8 br/mm vs 3.5 ± 0.9 br/mm, P=0.043) and lung mechanics (static elastance 61 ± 36 cmH2O /mL vs 113 ± 40 cmH2O/mL, P=0.008), but both effects were more pronounced in fetuses undergoing additional TO (2.1 ± 0.8 br/mm, P=0.001 and 31 ± 9 cmH2O/mL, P<0.0001 respectively). Both CDH-sham and CDH-TO fetuses treated with placebo had an increased medial wall thickness of peripheral pulmonary vessels (41.9 ± 2.9% and 41.8 ± 3.2%, vs 24.0 ± 2.9% in controls, P<0.0001). CDH fetuses treated with sildenafil, either with or without TO, had a medial thickness in the normal range (29.4% ± 2.6%). Finally, TO reduced gene expression of vascular endothelial growth factor and surfactant protein A and B, but this effect was counteracted by sildenafil.

CONCLUSION

In the rabbit model for CDH, the combination of maternal sildenafil and TO has a complementary effect on vascular and parenchymal lung development.

Longitudinal changes in lung size and intrapulmonary-artery Doppler during the second half of pregnancy in fetuses with congenital diaphragmatic hernia

OBJECTIVES

The objectives of the study are to evaluate longitudinal changes in lung size and intrapulmonary-artery (IPa) Doppler in fetuses with congenital diaphragmatic hernia (CDH) and assess their contribution in predicting neonatal survival.

METHODS

The observed/expected lung-to-head ratio (O/E-LHR) and IPa-pulsatility index (PI) and peak early diastolic reversed flow (PEDRF) were evaluated in a cohort of left-sided CDH fetuses managed expectantly during pregnancy. Longitudinal changes were analyzed by multilevel analysis, and their value to predict survival using the multiple logistic regression and decision-tree analysis was assessed.

RESULTS

A total of 232 scans were performed on 69 CDH fetuses. The O/E-LHR values remained unchanged during fetal monitoring, whereas IPa-PI and PEDRF showed a progressive increase throughout follow-up, becoming abnormal on average at 30 weeks of gestation. Absent/reversed end-diastolic velocity (EDV) in the IPa was observed in 20.3%. O/E-LHR and IPa Doppler indices were significantly associated with probability of survival (O/E-LHR ≥ 26%, odds ratio [OR] 19.0; IPa-PI <+2.0 z score, OR 3.0; and positive EDV, OR 7.4). All cases with IPa-reversed EDV died after birth.

CONCLUSION

While lung size remains stable during pregnancy, CDH fetuses show progressive deterioration in intrapulmonary blood flow. IPa Doppler evaluation may aid in predicting survival of CDH fetuses managed expectantly during pregnancy.