Maternal hyperoxygenation test in fetuses undergoing FETO for severe isolated congenital diaphragmatic hernia

Pulmonary vascular reactivity in growth restricted fetuses using computational modelling and machine learning analysis of fetal Doppler waveforms

The aim of this study was to investigate the pulmonary vasculature in baseline conditions and after maternal hyperoxygenation in growth restricted fetuses (FGR). A prospective cohort study of singleton pregnancies including 97 FGR and 111 normally grown fetuses was carried out. Ultrasound Doppler of the pulmonary vessels was obtained at 24-37 weeks of gestation and data were acquired before and after oxygen administration. After, Machine Learning (ML) and a computational model were used on the Doppler waveforms to classify individuals and estimate pulmonary vascular resistance (PVR). Our results showed lower mean velocity time integral (VTI) in the main pulmonary and intrapulmonary arteries in baseline conditions in FGR individuals. Delta changes of the main pulmonary artery VTI and intrapulmonary artery pulsatility index before and after hyperoxygenation were significantly greater in FGR when compared with controls. Also, ML identified two clusters: A (including 66% controls and 34% FGR) with similar Doppler traces over time and B (including 33% controls and 67% FGR) with changes after hyperoxygenation. The computational model estimated the ratio of PVR before and after maternal hyperoxygenation which was closer to 1 in cluster A (cluster A 0.98 ± 0.33 vs cluster B 0.78 ± 0.28, p = 0.0156). Doppler ultrasound allows the detection of significant changes in pulmonary vasculature in most FGR at baseline, and distinct responses to hyperoxygenation. Future studies are warranted to assess its potential applicability in the clinical management of FGR.

Congenital Diaphragmatic Hernia: Pulmonary Hypertension and Pulmonary Vascular Disease

This review provides a comprehensive summary of the current understanding of pulmonary hypertension (PH) in congenital diaphragmatic hernia, outlining the underlying pathophysiologic mechanisms, methods for assessing PH severity, optimal management strategies, and prognostic implications.

Pulmonary Vascular Regulation in the Fetal and Transitional Lung

Fetal lungs have fewer and smaller arteries with higher pulmonary vascular resistance (PVR) than a newborn. As gestation advances, the pulmonary circulation becomes more sensitive to changes in pulmonary arterial oxygen tension, which prepares them for the dramatic drop in PVR and increase in pulmonary blood flow (PBF) that occur when the baby takes its first few breaths of air, thus driving the transition from fetal to postnatal circulation. Dynamic and intricate regulatory mechanisms control PBF throughout development and are essential in supporting gas exchange after birth. Understanding these concepts is crucial given the role the pulmonary vasculature plays in the development of complications with transition, such as in the setting of persistent pulmonary hypertension of the newborn and congenital heart disease. An improved understanding of pulmonary vascular regulation may reveal opportunities for better clinical management.

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.

Maternal hyperoxygenation during pregnancy as a tool in fetal disease diagnosis and treatment

Maternal hyperoxygenation (MHO) consists of giving pregnant women (60% to 100%) oxygen through a facemask and using ultrasound assess or monitor the influence on fetal cardiovascular circulation. This review discusses the findings and the utility of acute and chronic MHO in various fetal diseases.

Minimally Invasive Fetal Surgery and the Next Frontier

Most patients with congenital anomalies do not require prenatal intervention. Furthermore, many congenital anomalies requiring surgical intervention are treated adequately after birth. However, there is a subset of patients with congenital anomalies who will die before birth, shortly after birth, or experience severe postnatal complications without fetal surgery. Fetal surgery is unique in that an operation is performed on the fetus as well as the pregnant woman who does not receive any direct benefit from the surgery but rather lends herself to risks, such as hemorrhage, abruption, and preterm labor. The maternal risks involved with fetal surgery have limited the extent to which fetal interventions may be performed but have, in turn, led to technical innovations that have significantly advanced the field. This review will examine congenital abnormalities that can be treated with minimally invasive fetal surgery and introduce the next frontier of prenatal management of fetal surgical pathology.

Prenatal management of congenital diaphragmatic hernia

Recently, two randomized controlled, prospective trials, the Tracheal Occlusion to Accelerate Lung Growth (TOTAL) trials, reported the outcomes on fetal endoluminal tracheal occlusion (FETO) for isolated left congenital diaphragmatic hernia (CDH). FETO significantly improved outcomes for severe hypoplasia. The effect in moderate cases, where the balloon was inserted later in pregnancy, did not reach significance. In a pooled analysis investigating the effect of the heterogeneity of the treatment effect by the time point of occlusion and severity, the difference may be explained by a difference in the duration of occlusion. Nevertheless, FETO carries a significant risk of preterm birth. The primary objective of this review is to provide an overview of the rationale for fetal intervention in CDH and the results of the randomized trials. The secondary objective is to discuss the technical aspects of FETO. Finally, recent developments of potential alternative fetal approaches will be highlighted.

Neonatal and fetal therapy of congenital diaphragmatic hernia-related pulmonary hypertension

Congenital diaphragmatic hernia (CDH) is a complex malformation characterised by a triad of pulmonary hypoplasia, pulmonary hypertension (PH) and cardiac ventricular dysfunction. Much of the mortality and morbidity in CDH is largely accounted for by PH, especially when persistent beyond the neonatal period and refractory to available treatment. Gentle ventilation, haemodynamic optimisation and pulmonary vasodilation constitute the foundations of neonatal treatment of CDH-related PH (CDH-PH). Moreover, early prenatal diagnosis, the ability to assess severity and the developmental nature of the condition generate the perfect rationale for fetal therapy. Shortcomings of currently available clinical therapies in combination with increased understanding of CDH pathophysiology have spurred experimental drug trials, exploring new therapeutic mechanisms to tackle CDH-PH. We herein discuss clinically available neonatal and fetal therapies specifically targeting CDH-PH and review the most promising experimental treatments and future research avenues.

Prenatal treprostinil reduces the pulmonary hypertension phenotype in the rat model of congenital diaphragmatic hernia

Background

Persistent pulmonary hypertension (PH) causes significant mortality and morbidity in infants with congenital diaphragmatic hernia (CDH). Since pulmonary vascular abnormalities in CDH develop early during foetal development, we hypothesized that prenatal maternal administration of treprostinil, through its anti-remodelling effect, would improve the PH-phenotype in the nitrofen rat model of CDH.

Methods

In a dose-finding study in normal, healthy pregnant rats, we demonstrated target-range foetal plasma treprostinil concentrations without signs of toxicity. Next, an efficacy study was performed assessing the effects of treprostinil administration at 900 and 1500ng/kg/min from gestational day (GD) 16 until term (GD 21) in CDH and control pups. Pulmonary vascular and airway morphometry, lung mechanics, and expression patterns of genes implicated in the prostaglandin vasoactive pathway were studied.

Findings

In rats maternal administration of 1500ng/kg/min treprostinil reached target foetal concentrations, with no detrimental maternal or foetal side-effects. Prenatal exposure to 900 and 1500 ng/kg/min treprostinil reduced the medial wall thickness (%MWT) (CDH·900, 38.5± 8·4%; CDH.1500, 40·2±9·7%; CDH, 46·6±8·2%; both p < 0·0001) in rat pups with CDH, however increased the %MWT in normal foetuses (C.T.900, 36·6±11·1%; C.T.1500, 36·9±9·3%; C.P., 26·9±6·2%; both p < 0·001). Pulmonary airway development, lung hypoplasia and pulmonary function were unaffected by drug exposure.

Interpretation

In pregnant rats maternally administered treprostinil crosses the placenta, attains foetal target concentrations, and is well tolerated by both mother and foetuses. This report shows a significant reduction of pulmonary arteriole muscularization with prenatal treprostinil in a nitrofen rat model, supporting the promise of this treatment approach for PH of CDH.

Funding

United Therapeutics Corporation provided treprostinil and financial support (ISS-2020-10879).

Early diagnosis and targeted approaches to pulmonary vascular disease in bronchopulmonary dysplasia

Pulmonary hypertension has emerged as a life-threatening disease in preterm infants suffering from bronchopulmonary dysplasia (BPD). Its development is closely linked to respiratory disease, as vasculogenesis and alveologenesis are closely interconnected. Once clinically significant, BPD-associated pulmonary hypertension (BPD-PH) can be challenging to manage, due to poor reversibility and multiple comorbidities frequently associated. The pulmonary vascular disease process underlying BPD-PH is the result of multiple innate and acquired factors, and emerging evidence suggests that it progressively develops since birth and, in certain instances, may begin as early as fetal life. Therefore, early recognition and intervention are of great importance in order to improve long-term outcomes. Based on the most recent knowledge of BPD-PH pathophysiology, we review state-of-the-art screening and diagnostic imaging techniques currently available, their utility for clinicians, and their applicability and limitations in this specific population. We also discuss some biochemical markers studied in humans as a possible complement to imaging for the detection of pulmonary vascular disease at its early stages and the monitoring of its progression. In the second part, we review pharmacological agents currently available for BPD-PH treatment or under preclinical investigation, and discuss their applicability, as well as possible approaches for early-stage interventions in fetuses and neonates. IMPACT: BPD-associated PH is a complex disease involving genetic and epigenetic factors, as well as environmental exposures starting from fetal life. The value of combining multiple imaging and biochemical biomarkers is emerging, but requires larger, multicenter studies for validation and diffusion. Since "single-bullet" approaches have proven elusive so far, combined pharmacological regimen and cell-based therapies may represent important avenues for research leading to future cure and prevention.

The Cellular and Molecular Effects of Fetoscopic Endoluminal Tracheal Occlusion in Congenital Diaphragmatic Hernia

Congenital diaphragmatic hernia (CDH) is a complex disease associated with pulmonary hypoplasia and pulmonary hypertension. Great strides have been made in our ability to care for CDH patients, specifically in the prenatal improvement of lung volume and morphology with fetoscopic endoluminal tracheal occlusion (FETO). While the anatomic effects of FETO have been described in-depth, the changes it induces at the cellular and molecular level remain a budding area of CDH research. This review will delve into the cellular and molecular effects of FETO in the developing lung, emphasize areas in which further research may improve our understanding of CDH, and highlight opportunities to optimize the FETO procedure for improved postnatal outcomes.

Expected small left heart size in the presence of congenital diaphragmatic hernia: Fetal values and Z-scores for infants confirmed to have no heart disease postnatally

OBJECTIVES

In fetuses with left-sided congenital diaphragmatic hernia (CDH), left heart structures may appear small, but usually normalize after birth in the absence of structural cardiac anomalies. To decrease the possibility of an erroneous diagnosis of structural heart disease, we identify normal values for left heart structures in the presence of left CDH and secondarily investigate the relationship of left heart size and survival to neonatal hospital discharge.

METHODS

Left heart structures [mitral valve (MV) and aortic valve (AoV) annulus diameter, left ventricle (LV) length and width] were measured by fetal echocardiogram in fetuses with left CDH and no congenital heart disease. We generated linear regression models to establish the relationship of gestational age for each left heart structure using data from fetuses who survived after birth. We calculated z-scores (normalized to gestational age), and assessed the relationship of survival to the size of each structure.

RESULTS

One hundred forty-two fetuses underwent fetal echocardiogram (median 25 weeks' gestation, IQR 23, 27 weeks). Left heart structures were deemed small when using published normative data from unaffected fetuses (z-scores: MV -1.09 ± 1.35, AoV -2.12 ± 1.16, LV length -1.36 ± 1.24, LV width -4.79 ± 0.79). CDH-specific models derived from log-transformed values yielded left-shifted distributions, reflecting the small structures (mean z-score lower by: MV 0.99 ± 0.30, AoV 2.04 ± 0.38, LV length 1.30 ± 0.36, and LV width 4.69 ± 0.28; p < 0.0001 for all comparisons). Non-survivors had worse z-scores than survivors for all measurements, but this did not reach statistical significance.

CONCLUSIONS

Log-transformed linear models generated new normative data for fetal left heart structures in left CDH, which may be used to allay antenatal concerns regarding structural left heart anomalies. There were no significant differences in z-scores between survivors and non-survivors, suggesting that in the absence of true structural disease, cardiac evaluation is not predictive in isolation and that causes of mortality are likely multifactorial in this population.

Fetal Hemodynamic Response to Maternal Oxygenation in Normal and Complicated Pregnancies

Maternal oxygenation (MO) is widely applied in obstetrics. Scholars have conducted numerous studies on maternal hyperoxygenation and have reported many theoretical and applied achievements and a number of different points of view. The main purpose of this article is to discuss the effect of maternal oxygenation on fetal circulation during normal and complicated pregnancies and to ascertain its potential side effects and research gaps in this field. In complicated pregnancies, the fetus may benefit from oxygen therapy. However, large randomized controlled trials and longitudinal studies are necessary to support the widespread application of maternal oxygenation in this context.

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.

Maternal hyperoxygenation in congenital heart disease

The importance of prenatal diagnosis and fetal intervention has been increasing as a preventative strategy for improving the morbidity and mortality in congenital heart disease (CHD). The advancements in medical imaging technology have greatly enhanced our understanding of disease progression, assessment, and impact in those with CHD. In particular, there has been a growing focus on improving the morbidity and mortality of fetuses diagnosed with left-sided lesions. The disruption of fetal hemodynamics resulting from poor structural developmental of the left outflow tract during cardiogenesis is considered a major factor in the progressive lethal underdevelopment of the left ventricle (LV). This positive feedback cycle of inadequate flow and underdevelopment of the LV leads to a disrupted fetal circulation, which has been described to impact fetal brain growth where systemic outflow is poor and, in some cases, the fetal lungs in the setting of a restrictive interatrial communication. For the past decade, maternal hyperoxygenation (MH) has been investigated as a diagnostic tool to assess the pulmonary vasculature and a therapeutic agent to improve the development of the heart and brain in fetuses with CHD with a focus on left-sided cardiac defects. This review discusses the findings of these studies as well as the utility of acute and chronic administration of MH in CHD.

Ebstein's anomaly: epidemiological analysis and presentation of different prenatal management

OBJECTIVES

To present the crucial role of echocardiographic examination in perinatal care and analyze influence of prenatal treatment for neonatal outcome. Furthermore, the attempt to answer the question if there was any relationship between the occurrence of fetal Ebstein's anomaly and environmental risk factors in polish population.

METHODS

Forty-five prenatal diagnoses of Ebstein's anomaly were compiled over the 21-year period (1998‒2018) form our single unit. The analysis included the assessment of maternal parameters (age, past obstetric history, and place of residence) and fetal parameters (sex, gestational age, anatomy, the fetal cardiovascular condition assessed by the CVPS, associated extracardiac anomalies or malformations, prenatal treatment, delivery and follow-up).

RESULTS

The average age of gravida was 29.5 years (± 5.2 years) and gravidae <35 years of age accounted for 80% . There were 43 singleton pregnancies and 2 cases of multiple pregnancy. Ebstein's anomaly was mostly (averagely) diagnosed at 28th week of gestation. Forty-three fetuses had normal karyotypes and two had trisomy 21. Cardiomegaly was present in 91% (41) of fetuses. The average heart area to chest area ratio was 0.56 (± 0.12). In 21 cases, there was only fetal monitoring - echocardiographic examinations and postnatal mortality was 44.4%. In 5 cases, transplacental digoxin treatment was administered and mortality was: 40%. In another 5 cases, only steroid therapy was applied and postnatal mortality was 100%. Steroids and transplacental digoxin treatment were administered in 11 cases and mortality was 63.6%. In 3 last cases transplacental digoxin treatment, steroids and maternal hyperoxygenation therapy were given and mortality was 0%. Cesarean section rate was 49%. Moreover, due to Ebstein's anomaly regional peak of occurrence benzopyrene was deliberated as environmental risk factor.

CONCLUSIONS

Fetal Ebstein's anomaly occurred in our population in healthy young women, expecting their first child and malformation was not related to fetus gender, nor to maternal health condition. Our data can be a new signal for the development of novel treatment strategies in therapy in fetuses with Ebstein's anomaly.

Hyperoxygenation in pregnancy exerts a more profound effect on cardiovascular hemodynamics than is observed in the nonpregnant state

BACKGROUND

Supplemental oxygen is administered to pregnant women in many different clinical scenarios in obstetric practice. Despite the accepted uses for maternal hyperoxygenation, the impact of hyperoxia on maternal hemodynamic indices has not been evaluated. As a result, there is a paucity of data in the literature in relation to the physiological changes to the maternal circulation in response to supplemental oxygen.

OBJECTIVE

The hemodynamic effects of oxygen therapy are under-recognized and the impact of hyperoxygenation on maternal hemodynamics is currently unknown. Using noninvasive cardiac output monitoring which employs transthoracic bioreactance, we examined the effect of brief hyperoxygenation on cardiac index, systemic vascular resistance, blood pressure, stroke volume, and heart rate in pregnant mothers during the third trimester, compared with those effects observed in a nonpregnant population subjected to the same period of hyperoxygenation.

STUDY DESIGN

Hemodynamic monitoring was performed in a continuous manner over a 30-minute period using noninvasive cardiac output monitoring. Hyperoxygenation (O₂ 100% v/v inhalational gas) was carried out at a rate of 12 L/min via a partial non-rebreather mask for 10-minutes. Cardiac index, systemic vascular resistance, stroke volume, heart rate, and blood pressure were recorded before hyperoxygenation, at completion of hyperoxygenation, and 10 minutes after the cessation of hyperoxygenation. Two-way analysis of variance with repeated measures was used to assess the change in hemodynamic indices over time and the differences between the 2 groups.

RESULTS

Forty-six pregnant and 20 nonpregnant women with a median age of 33 years (interquartile range, 26-38 years) and 32 years (interquartile range, 28-37 years) were recruited prospectively, respectively (P=.82). The median gestational age was 35 weeks (33-37 weeks). In the pregnant group, there was a fall in cardiac index during the hyperoxygenation exposure period (P=.009) coupled with a rise in systemic vascular resistance with no recovery at 10 minutes after cessation of hyperoxygenation (P=.02). Heart rate decreased after hyperoxygenation exposure and returned to baseline by 10 minutes after cessation of therapy. There was a decrease in stroke volume over the exposure period, with no change in systolic or diastolic blood pressure. In the nonpregnant group, there was no significant change in the cardiac index, systemic vascular resistance, stroke volume, heart rate, or systolic or diastolic blood pressure during the course of exposure to hyperoxygenation.

CONCLUSION

Hyperoxygenation during the third trimester is associated with a fall in maternal cardiac index and a rise in systemic vascular resistance without recovery to baseline levels at 10 minutes after cessation of hyperoxygenation. The hemodynamic changes that were observed in this study in response to hyperoxygenation therapy during pregnancy could counteract any intended increase in oxygen delivery. The observed maternal effects of hyperoxygenation call for a reevaluation of the role of hyperoxygenation treatment in the nonhypoxemic pregnant patient.

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.

Current and future antenatal management of isolated congenital diaphragmatic hernia

Congenital diaphragmatic hernia is surgically correctable, yet the poor lung development determines mortality and morbidity. In isolated cases the outcome may be predicted prenatally by medical imaging. Cases with a poor prognosis could be treated before birth. However, prenatal modulation of lung development remains experimental. Fetoscopic endoluminal tracheal occlusion triggers lung growth and is currently being evaluated in a global clinical trial. Prenatal transplacental sildenafil administration may in due course be a therapeutic approach, reducing the occurrence of persistent pulmonary hypertension, either alone or in combination with fetal surgery.

Fetoscopic tracheal occlusion for treatment of non-isolated congenital diaphragmatic hernia

Fetoscopic endotracheal occlusion (FETO) is a prenatal treatment that may increase survival in severe congenital diaphragmatic hernia (CDH). In the USA, FETO is offered for isolated severe left-sided CDH in the context of an FDA-approved feasibility study. FETO in non-isolated cases of severe CDH is only performed with a compassionate use exemption from US regulatory bodies. Anomalies frequently associated with CDH include congenital cystic lesions of the lung and cardiac defects. We describe two cases of non-isolated severe left-sided CDH that underwent prenatal FETO, survived after birth and underwent postnatal surgical repair. The potential benefit of FETO in this setting is discussed. © 2017 John Wiley & Sons, Ltd.

Lung size and liver herniation predict need for extracorporeal membrane oxygenation but not pulmonary hypertension in isolated congenital diaphragmatic hernia: systematic review and meta-analysis

OBJECTIVES

To identify antenatal predictors of persistent pulmonary hypertension (PPH) and the need for extracorporeal membrane oxygenation (ECMO) in fetuses with congenital diaphragmatic hernia (CDH).

METHODS

We performed a systematic literature review on antenatal diagnostic tests in fetuses with isolated CDH. The primary outcomes assessed were PPH within 28 days of age and the need for ECMO. Quality of studies was assessed with the QUADAS-2 tool. Meta-analysis was performed when at least three studies reported on the same test. Sensitivity analysis was performed according to prenatal management of CDH (tracheal occlusion vs expectant management).

RESULTS

Thirty-eight studies met the inclusion criteria. Fifteen reported on the incidence of PPH only, 19 on the need for ECMO only and four reported on both outcomes. The general quality of the studies was moderate; most studies were retrospective (61%) and single-center series (92%). One study included only fetuses undergoing tracheal occlusion, 22 included only fetuses managed expectantly in utero and 15 included both populations. We could not identify antenatal predictors of PPH. The need for ECMO was predicted by parameters indicative of lung size: lung-to-head ratio (LHR) (relative risk (RR) for LHR < 1, 1.65 (95% CI, 1.27-2.14)) and observed/expected LHR (standardized mean difference (SMD), -0.70 (95% CI, -0.98 to -0.42)) measured by ultrasound and observed/expected total lung volume (SMD, -1.00 (95% CI, -1.52 to -0.48)) measured by magnetic resonance imaging. Liver herniation was also associated with an increased risk of need for ECMO (RR, 3.04 (95% CI, 2.23-4.14)). These results were confirmed by a sensitivity analysis of studies that included only expectantly managed cases. Data on vascular assessment for the prediction of PPH could not be pooled as most of the parameters were evaluated in a single series or in different series by the same principal investigator.

CONCLUSIONS

In fetuses with CDH, lung size and liver herniation predict the need for ECMO, however a predictor for PPH is still lacking. Further studies aimed at diagnosing impaired vascular development in utero should therefore be undertaken. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Fetal imaging and therapy for CDH-Current status

In congenital diaphragmatic hernia (CDH), herniation of the abdominal organs into the fetal chest causes pulmonary hypoplasia and pulmonary hypertension, the main causes of neonatal mortality. As antenatal ultrasound screening improves, the risk of postnatal death can now be better predicted, allowing for the identification of fetuses that might most benefit from a prenatal intervention. Fetoscopic tracheal occlusion is being evaluated in a large international randomized controlled trial. We present the antenatal imaging approaches that can help identify fetuses that might benefit from antenatal therapy, and review the evolution of fetal surgery for CDH to date.

Sustained maternal hyperoxygenation improves aortic arch dimensions in fetuses with coarctation

The aim was to investigate the impact of maternal hyperoxygenation (HO) on cardiac dimensions in fetuses with isolated Coarctation (CoA). Fetal echocardiography was performed serially in 48 fetuses with CoA and gestation age matched normal fetues. The Z-scores for the mitral valve (MV), tricuspid valve (TV), aortic valve (AV), ascending aorta (AAo), isthmus, pulmonary valve (PV), main pulmonary artery (MPA), and descending aorta (DAo) were measured and compared among normal fetuses, CoA fetuses with oxygen and CoA fetuses with air. In the group with oxygen, 6 L/min oxygen was administered to the mother using a face mask. Regression analyses were performed to identify potential factors for HO outcome. The left heart dimension Z-scores increased gradually during HO therapy periods, especially at 4 weeks after oxygen therapy (P < 0.05). As for the case group with air, the left heart dimension remained unchanged. The duration of HO was associated with aortic arch Z-scores (adjusted R² = 0.199, 0.60 for AAO and isthmus, respectively). Sustained maternal middle-flow oxygenation can be safely used to improve left heart dimensions in fetuses with isolated CoA. The duration of HO were associated with treatment outcome. These findings may provide useful information for developing novel treatment strategies.

Pilot study of chronic maternal hyperoxygenation and effect on aortic and mitral valve annular dimensions in fetuses with left heart hypoplasia

OBJECTIVE

Acute maternal hyperoxygenation (AMH) results in increased fetal left heart blood flow. Our aim was to perform a pilot study to determine the safety, feasibility and direction and magnitude of effect of chronic maternal hyperoxygenation (CMH) on mitral and aortic valve annular dimensions in fetuses with left heart hypoplasia (LHH) after CMH.

METHODS

Gravidae with fetal LHH were eligible for inclusion in a prospective evaluation of CMH. LHH was defined as: sum of aortic and mitral valve annuli Z-scores < -4.5, arch flow reversal and left-to-right or bidirectional atrial level shunting without hypoplastic left heart syndrome or severe aortic stenosis. Gravidae with an affected fetus and with ≥ 10% increase in aortic/combined cardiac output flow after 10 min of AMH at 8 L/min 100% fraction of inspired oxygen were offered enrollment. Nine gravidae were enrolled from February 2014 to January 2015. The goal therapy was ≥ 8 h daily CMH from enrollment until delivery. Gravidae who were cared for from July 2012 to October 2014 with fetal LHH and no CMH were identified as historical controls (n = 9). Rates of growth in aortic and mitral annuli over the final trimester were compared between groups using longitudinal regression.

RESULTS

There were no significant maternal or fetal complications in the CMH cohort. Mean gestational age at study initiation was 29.6 ± 3.2 weeks for the intervention group and 28.4 ± 1.8 weeks for controls (P = 0.35). Mean relative increase in aortic/combined cardiac output after AMH was 35.3% (range, 18.1-47.9%). Median number of hours per day on CMH therapy was 9.3 (range, 6.5-14.6) and median duration of CMH was 48 (range, 33-84) days. Mean mitral annular growth was 0.19 ± 0.05 mm/week compared with 0.14 ± 0.05 mm/week in CMH vs controls (mean difference 0.05 ± 0.05 mm/week, P = 0.33). Mean aortic annular growth was 0.14 ± 0.03 mm/week compared with 0.13 ± 0.03 mm/week in CMH vs controls (mean difference 0.01 ± 0.03 mm/week, P = 0.75). More than 9 h CMH daily (n = 6) was associated with better growth of the aortic annulus in intervention fetuses (0.16 ± 0.03 vs 0.08 ± 0.02 mm/week, P = 0.014).

CONCLUSIONS

CMH is both safe and feasible for continued research. In this pilot study, the effect estimates of annular growth, using the studied method of delivery and dose of oxygen, were small. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Learning Curve for Intrapulmonary Artery Doppler in Fetuses with Congenital Diaphragmatic Hernia

Objective: To assess the learning curve for intrapulmonary artery Doppler in fetuses with congenital diaphragmatic hernia (CDH). Methods: Three fetal medicine fellows with the theoretic knowledge, but without prior experience, in the evaluation of intrapulmonary artery Doppler in CDH fetuses were selected. Each trainee and 1 experienced explorer assessed the intrapulmonary artery in the contralateral lung to the side of the hernia for calculation of 2 Doppler parameters - pulsatility index (PI) and peak early diastolic reversed flow (PEDRF) - in a cohort of 90 consecutive CDH fetuses. The average difference between the 3 trainees and the expert was calculated. A difference below 15% was considered as accurate measurement. The average learning curve was delineated using the cumulative sum analysis (CUSUM). Results: Among the total 270 intrapulmonary artery Doppler measurements performed by the 3 trainees, the number of failed examinations was 14 (15.6%) and 16 (17.8%) for PI and PEDRF, respectively. The CUSUM plots demonstrate that the learning curve was achieved by 53 and 63 tests performed for calculations of the intrapulmonary artery PI and PEDRF, respectively. Conclusion: Competence in Doppler evaluation of the intrapulmonary artery in CDH fetuses is achieved only after intensive continuous training.

Maternal hyperoxygenation improves left heart filling in fetuses with atrial septal aneurysm causing impediment to left ventricular inflow

OBJECTIVES

Aneurysm of the atrial septum (AAS) with excessive excursion of septum primum into the left atrium is an uncommon and relatively benign fetal condition associated with impediment to left ventricular (LV) filling and the appearance of a slender, but apex-forming, LV on fetal echocardiography. Impediment to filling can be severe, creating the image of LV hypoplasia with retrograde aortic flow. We hypothesize that maternal hyperoxygenation alters atrial septal position, improves LV filling, and normalizes aortic flow in fetuses with AAS by increasing fetal pulmonary venous return.

METHODS

Fetal echocardiography was performed prior to, and at 10 min of, maternal hyperoxygenation in 12 fetuses with AAS who were referred to our center because of LV hypoplasia. Atrial septal excursion (ASE), LV and right ventricular (RV) sphericity index (SI) and direction of flow in the aortic isthmus, as determined by Doppler, were measured.

RESULTS

With maternal hyperoxygenation, mean ± SD ASE decreased (0.76 ± 0.17 before maternal hyperoxygenation vs 0.53 ± 0.23 after maternal hyperoxygenation; P < 0.01), consistent with increased pulmonary venous return, LV-SI increased (0.29 ± 0.06 vs 0.42 ± 0.06; P < 0.001), indicating increased LV filling, and the direction of aortic isthmus flow changed from retrograde in all cases prior to maternal hyperoxygenation to antegrade in 10 and to bidirectional in two. RV-SI remained unchanged (0.53 ± 0.13 vs 0.52 ± 0.10; P = 0.7).

CONCLUSIONS

In cases of AAS, short-term maternal hyperoxygenation increases fetal pulmonary venous return, substantially alters LV geometry and promotes antegrade flow in the aortic isthmus. This demonstrates proof-of-concept that maternal hyperoxygenation can improve filling of the left side of the fetal heart in AAS.

Prenatal prediction of pulmonary arterial hypertension in congenital diaphragmatic hernia

OBJECTIVE

To evaluate the role of prenatal prognostic markers obtained routinely by ultrasound examination and magnetic resonance imaging (MRI) in the prediction of development of postnatal pulmonary arterial hypertension (PAH) in isolated congenital diaphragmatic hernia (CDH).

METHODS

One hundred and ten cases of isolated CDH were referred to our fetal medicine unit between January 2004 and April 2013. Mortality and morbidity rates were reviewed for those presenting with postnatal PAH. The following prenatal markers were evaluated as potential predictive factors of PAH: liver position, side of the CDH defect, lung area to head circumference ratio (LHR) and observed/expected LHR (o/e-LHR), which were measured by ultrasound, and observed/expected total fetal lung volume (o/e-TFLV), which was measured by MRI. Univariable logistic regression was used to assess associations.

RESULTS

PAH was significantly associated with perinatal mortality and morbidity (P < 0.001). The occurrence of PAH decreased significantly with an increasing LHR, o/e-LHR and o/e-TFLV and was significantly increased for cases with an intrathoracic liver, but not for those with right-sided defects. Univariable regression revealed that o/e-TFLV (odds ratio (OR), 0.9 (95% CI, 0.86-0.95); P < 0.05 for percentage unit change in o/e), LHR (OR, 0.19 (95% CI, 0.09-0.40); P < 0.05 for unit change), o/e-LHR (OR, 0.95 (95% CI, 0.93-0.98); P < 0.05 for percentage unit change in o/e) and liver position (OR, 2.82 (95% CI, 1.13-7.00); P < 0.05 for intrathoracic liver) were significant predictors of subsequent PAH. No differences were found after adjusting for gestational age at delivery. The areas under the receiver-operating characteristics curve were 0.80 and 0.75 for o/e-TFLV and o/e-LHR, respectively.

CONCLUSION

In cases of CDH, PAH is associated with high rates of mortality and morbidity. Routinely obtained prenatal markers, usually used for the assessment of pulmonary hypoplasia, are also relevant for the postnatal prediction of PAH.

Advances in prenatal diagnosis of congenital diaphragmatic hernia

Over the past 20 years, prenatal detection of congenital diaphragmatic hernia (CDH) has improved worldwide, reaching up to 60% in Europe. Pulmonary hypoplasia and persistent pulmonary hypertension are the two main determinants of neonatal mortality and morbidity, so new tools have been focused on their evaluation. Fetal surgery for severe cases requires proper evaluation of the prognosis of fetuses with CDH. Observed-to-expected lung-to-head ratio, liver position, and total lung volume measured by magnetic resonance are the prognostic factors most often used, and have been shown to correlate not only with neonatal mortality but also with morbidity. In daily practice, pulmonary hypertension by itself, although most often associated with lung hypoplasia, is more difficult to predict.

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.

Prenatal management of the fetus with isolated congenital diaphragmatic hernia in the era of the TOTAL trial

Congenital diaphragmatic hernia (CDH) may be isolated or associated with other structural anomalies, the latter with poor prognosis. The defect allows viscera to herniate through the defect into the chest, competing for space with the developing lungs. At birth, pulmonary hypoplasia leads to respiratory insufficiency and persistent pulmonary hypertension that is lethal in up to 30% of patients. When isolated, survival chances can be predicted by antenatal measurement of lung size and liver herniation. Chromosomal microarrays and exome sequencing contribute to understanding genetic factors underlying isolated CDH. Prenatal intervention aims at stimulating lung development, clinically achieved by percutaneous fetal endoscopic tracheal occlusion (FETO) under local anesthesia. The Tracheal Occlusion To Accelerate Lung growth trial (www.totaltrial.eu) is an international randomized trial investigating the role of fetal therapy for severe and moderate pulmonary hypoplasia. Despite an apparent increase in survival following FETO, the search for lesser invasive and more potent prenatal interventions must continue.

Prediction of Neonatal Respiratory Function and Pulmonary Hypertension in Fetuses with Isolated Congenital Diaphragmatic Hernia in the Fetal Endoscopic Tracleal Occlusion Era: A Single-Center Study

Objective: To correlate prenatal indicators of pulmonary hypoplasia with neonatal lung function and pulmonary hypertension (PHT) in isolated congenital diaphragmatic hernia (iCDH). Materials and Methods: Prospective single-center study on 40 fetuses with iCDH either expectantly managed (n = 13) or undergoing tracheal occlusion (n = 27). Prenatal predictors included observed/expected lung-head ratio (O/E LHR), observed/expected total fetal lung volume, fetal pulmonary reactivity to maternal O2 administration (Δpulsatility index, ΔPI) and liver-to-thorax ratio (LiTR) as measured in the second and third trimesters. Postnatal outcome measures included survival until discharge, best oxygenation index (OI) and alveolar-arterial oxygen gradient [D(A-a)O2] in the first 24 h of life and the occurrence of PHT in the first 28 days of life. Results: Median gestational age (GA) at evaluations was 27.2 and 34.3 weeks. GA at delivery was 36.0 weeks, and overall survival was 55%. In the second trimester, measurement of lung size, LiTR and pulmonary reactivity were significantly related to survival and the best OI and D(A-a)O2.The occurrence of PHT was better predicted by ΔPI and LiTR. Conclusions: O/E LHR, LiTR and vascular reactivity correlate with ventilatory parameters in the first 24 h of life. Occurrence of PHT at ≥28 days was best predicted by LiTR and ΔPI, but not by lung size.

An evidence-based review of the current treatment of congenital diaphragmatic hernia

Congenital diaphragmatic hernia is a rare but severe condition affecting 1 in 2000 to 3000 newborns with a survival rate of 67%. Although regular antenatal screening allows prenatal diagnosis in many cases, traditionally treatment has been based on postnatal surgical repair. Recent literature has pointed out the survival benefits of initial stabilization and the use of gentle ventilation strategies prior to definitive treatment, shifting the trend from immediate to delayed surgical repair. Advances in fetal intervention have allowed the introduction of fetal endoscopic tracheal occlusion as a method to hasten lung development before birth in order to minimize postnatal morbidity. Despite appropriate treatment, the long-term outcomes of these patients are plagued with numerous complications, associated with the primary pathology and also aggressive therapeutic measures. International centers of excellence have recently come together in an effort to standardize the care of such patients in hopes of maximizing their outcomes.

Usefulness of lung-to-head ratio and intrapulmonary arterial Doppler in predicting neonatal morbidity in fetuses with congenital diaphragmatic hernia treated with fetoscopic tracheal occlusion

OBJECTIVE

To explore the potential value of intrapulmonary artery Doppler velocimetry in predicting neonatal morbidity in fetuses with left-sided congenital diaphragmatic hernia (CDH) treated with fetoscopic tracheal occlusion (FETO).

METHODS

Observed/expected lung-to-head ratio (O/E-LHR), and intrapulmonary Doppler pulsatility index and peak early-diastolic reversed flow were evaluated within 24 h before FETO in a consecutive cohort of 51 fetuses with left-sided CDH at between 24 and 33 weeks' gestation. Lung Doppler parameters were converted into Z-scores and defined as abnormal if the pulsatility index had a Z-score of > 1.0 or the peak early-diastolic reversed flow had a Z-score of > 3.5. The association of O/E-LHR and Doppler velocimetry with neonatal outcome was assessed using multiple linear or logistic regression analysis adjusted for gestational age at birth.

RESULTS

Among the 26 fetuses that survived, 18 (69.2%) had normal and eight (30.8%) had abnormal Doppler values. O/E-LHR was not associated with neonatal morbidity in surviving fetuses. Compared with the group with normal Doppler parameters, cases with abnormal intrapulmonary Doppler were associated with a significant increase in the duration of mechanical ventilation (average increase of 21.2 (95% CI, 9.99-32.5) days; P < 0.01), conventional ventilation (15.2 (95% CI, 7.43-23.0) days; P < 0.01), high-frequency ventilation (6.34 (95% CI, 0.69-11.99) days; P < 0.05), nitric oxide therapy (5.73 (95% CI, 0.60-10.9) days; P < 0.05), oxygen support (36.5 (95% CI, 16.3-56.7) days; P < 0.01), parenteral nutrition (19.1 (95% CI, 7.53-30.7) days; P < 0.01) and stay in neonatal intensive care unit (42.7 (95% CI, 22.9-62.6) days; P < 0.001), and with significantly higher rates of high-frequency ventilation (87.5 vs. 44.4%;P < 0.05), oxygen requirement at 28 days of age (75.0 vs. 11.1%; P < 0.01), gastroesophageal reflux (62.5 vs. 22.2%; P < 0.05) and tube feeding at discharge (37.5 vs. 5.56%; P < 0.05).

CONCLUSION

As previously reported, O/E-LHR did not predict neonatal morbidity. In contrast, intrapulmonary artery Doppler evaluation was predictive of neonatal morbidity in CDH fetuses treated with FETO.

Intrauterine surgery--choices and limitations

BACKGROUND

The past decade has seen much progress in intrauterine surgery. Randomized trials have documented the benefit of some procedures of this type for the unborn child.

METHOD

Selective literature review

RESULTS

Randomized trials have demonstrated the benefit of fetoscopic laser coagulation of placental anastomoses in twin-to-twin transfusion syndrome (TTTS) and of intrauterine surgery via hysterotomy for the repair of spina bifida. Other fetoscopic procedures have yielded promising initial results but are not yet supported by findings from randomized trials. Some intrauterine surgical procedures must still be considered experimental in view of the lack of randomized trials and the rarity of the conditions they are designed to treat. Fetoscopic laser coagulation for TTTS is by far the most common procedure in fetal surgery; TTTS arises in roughly 1 in 2500 pregnancies. The other procedures discussed in this article are performed much less often and for rarer indications. In general, intrauterine surgery is indicated only to treat conditions that would otherwise lead to intrauterine death or irreversible prenatal damage.

CONCLUSION

Intrauterine surgery is a rapidly developing field. Prenatal intervention by laser coagulation is indicated to treat severe TTTS, as its benefit has been shown in a randomized trial. Not enough evidence is yet available for the possible benefit of intrauterine surgery to treat myelomeningocele and congenital diaphragmatic hernia. Other indications are experimental. When an indication for intrauterine surgery exists, the parents should be informed and, depending on their wishes, referred to a center where it can be performed.

Recent advances in the management of congenital diaphragmatic hernia

PURPOSE OF REVIEW

Congenital diaphragmatic hernia (CDH) is a rare developmental defect resulting in variable degrees of lung and pulmonary vasculature hypoplasia. Whereas many high-volume centers have recently reported increased survival rates, this has not been the collective trend. One potential explanation for this is inconsistent perinatal care among centers.

RECENT FINDINGS

Significant efforts have been made to identify prenatally those fetuses that will be most severely affected. A number of radiologic features have shown promise for achieving this goal as well as identifying fetuses that may benefit from prenatal intervention. When CDH is antenatally diagnosed, early referral to a tertiary center is recommended. Centers that routinely use postnatal management protocols have demonstrated improved overall survival rates including increased survival in high-risk CDH patients.

SUMMARY

As a result of advancements in perinatal care, more severely affected newborns with CDH are now surviving. These patients may experience a number of associated morbidities which affect not only their health but overall quality of life. A multidisciplinary approach to the long-term care of these patients will allow early identification and management of these morbidities.

Results of fetal endoscopic tracheal occlusion for congenital diaphragmatic hernia and the set up of the randomized controlled TOTAL trial

In isolated congenital diaphragmatic hernia, lung size and/or the position of the liver are predictive of neonatal outcome. Percutaneous Fetal Endoscopic Tracheal Occlusion (FETO) by a balloon can be undertaken to prompt lung growth in the worst cases. The feasibility and safety of FETO is no longer at stake, and it is associated with an apparent increase in neonatal survival. The gestational age at birth, the pre-existing lung size, the ability to remove the balloon prior to birth, and the lung response are predicting outcome. The most frequent complication is preterm premature rupture of the membranes, and as a consequence preterm delivery, which also complicates balloon removal. We have set up a randomized trial for the formal evaluation of FETO in Europe, including criteria for fetoscopy centers. Training of European as well as North American centers is taking place, so that the procedure could be safely and more widely offered.

Congenital diaphragmatic hernia: still a moving target

The primary therapeutic target for congenital diaphragmatic hernia (CDH) patients has shifted from emergency surgical repair towards a non-operative emergency of the newborn treated by interdisciplinary teams. The increased understanding of the epidemiological and pathophysiological aspects of CDH have led to an improved knowledge and application of prenatal diagnosis, postnatal ventilation strategies, treatment of associated pulmonary hypertension and the role of extracorporeal membrane oxygenation therapy. In the surgical field, the perspectives have changed with delayed CDH repair, the introduction of minimally invasive surgery and use of prosthetic material for closure of large defects. With decreased mortality, long term multi-organ morbidity has increased in some survivors. In the near future, randomized controlled trials on different aspects of therapy will determine evidence-based optimal care.

Technical aspects of fetal endoscopic tracheal occlusion for congenital diaphragmatic hernia

In isolated congenital diaphragmatic hernia, prenatal prediction is made based on measurements of lung size and the presence of liver herniation into the thorax. A subset of fetuses likely to die in the postnatal period is eligible for fetal intervention that can promote lung growth. Rather than anatomical repair, this is now attempted by temporary fetal endoscopic tracheal occlusion (FETO). Herein we describe purpose-designed instruments that were developed thanks to a grant from the European Commission. The feasibility and safety of FETO have now been demonstrated in several active fetal surgery programs. The most frequent complication of the procedure is preterm premature rupture of the membranes, which is probably iatrogenic in nature. It does have an impact on gestational age at delivery and complicates balloon removal. FETO is associated with an apparent increase in survival compared with same severity controls, although this needs to be evaluated in a formal trial. The time has come to do so.