Treprostinil in Neonates with Congenital Diaphragmatic Hernia-Related Pulmonary Hypertension.

OBJECTIVE: To describe our experience with treprostinil, evaluate correlations with cardiac function, and assess for adverse effects in neonates with congenital diaphragmatic hernia-related pulmonary hypertension (CDH-PH). STUDY DESIGN: A retrospective review of a single-center prospective registry at a quaternary care children's hospital. Patients included in the study had CDH-PH treated with treprostinil between April 2013 and September 2021. Assessed outcomes were brain-type natriuretic peptide levels and quantitative echocardiographic parameters collected at baseline, 1 week, 2 weeks, and 1 month after treprostinil initiation. Right ventricular (RV) function was assessed by tricuspid annular plane systolic excursion Z-score and speckle tracking echocardiography (global longitudinal and free wall strain). Septal position and left ventricular (LV) compression were assessed by eccentricity index and M-mode Z-scores. RESULTS: Fifty-one patients were included, with an average expected/observed lung-to-head ratio of 28.4 ± 9.0%. Most patients required extra-corporeal membrane oxygenation (n = 45, 88%). Survival to hospital discharge was 31/49 (63%). Treprostinil was initiated at a median age of 19 days with a median effective dose of 34 ng/kg/minute. Median baseline brain-type natriuretic peptide level decreased from 416.9 pg/mL to 120.5 pg/mL after 1 month. Treprostinil was associated with improved tricuspid annular plane systolic excursion Z-score, RV global longitudinal strain, RV free wall strain, LV eccentricity index, and LV diastolic and systolic dimensions, reflecting less compression by the RV, regardless of ultimate patient survival. No serious adverse effects were recorded. CONCLUSIONS: In neonates with CDH-PH, treprostinil administration is well tolerated and is associated with improved RV size and function.

Ethics Considerations Regarding Artificial Womb Technology for the Fetonate.

Since the early 1980's, with the clinical advent of in vitro fertilization resulting in so-called "test tube babies," a wide array of ethical considerations and concerns regarding artificial womb technology (AWT) have been described. Recent breakthroughs in the development of extracorporeal neonatal life support by means of AWT have reinitiated ethical interest about this topic with a sense of urgency. Most of the recent ethical literature on the topic, however, pertains not to the more imminent scenario of a physiologically improved method of neonatal care through AWT, but instead to the remote scenario of "complete ectogenesis" that imagines human gestation occurring entirely outside of the womb. This scoping review of the ethical literature on AWT spans from more abstract concerns about complete ectogenesis to more immediate concerns about the soon-to-be-expected clinical life support of what we term the fetal neonate or fetonate. Within an organizing framework of different stages of human gestational development, from conception to the viable premature infant, we discuss both already identified and newly emerging ethical considerations and concerns regarding AWT and the care of the fetonate.

The EXTrauterine Environment for Neonatal Development: Present and Future.

Despite advances in clinical care and modest improvement in mortality rates for extreme prematurity, morbidity remains a significant challenge. The ideal environment to support prematurity would be fluidic and rely on natural fetal circulation to mimic the natural fetal amniotic environment, yet such an environment has been unsuccessful in long-term support until recently. Our group has succeeded in developing such a support system to foster fetal growth in the premature lamb model that shows promise for clinical translation. Here, we describe the EXTrauterine Environment for Neonatal Development (EXTEND) from its conception onwards, review published literature on fetal development and support of the premature lamb model in EXTEND, and discuss future applications.

Fetoscopic insufflation of heated-humidified carbon dioxide during simulated spina bifida repair is safe under controlled anesthesia in the fetal lamb.

OBJECTIVE: To assess the safety of Partial-Amniotic-Insufflation-of-heated-humidified-CO2 (hPACI) during fetoscopic spina bifida repair (fSB-repair). METHOD: A simulated fSB-repair through an exteriorized uterus under hPACI was performed in 100-day fetal lambs (term = 145 days) under a laboratory anesthesia protocol (n = 5; group 1) which is known to induce maternal-fetal acidosis and hypercapnia. Since these may not occur clinically, we applied a clinical anesthesia protocol (n = 5; group 2), keeping maternal parameters within physiological conditions, that is, controlled maternal arterial carbon dioxide (CO2) pressure (pCO2  = 30 mmHg), blood pressure (≥67 mmHg), and temperature (37.1-39.8°C). Our superiority study used fetal pH as the primary outcome. RESULTS: Compared to group 1, controlled anesthesia normalized fetal pH (7.23 ± 0.02 vs. 7.36 ± 0.02, p < 0.001), pCO2 (70.0 ± 9.1 vs. 43.0 ± 1.0 mmHg, p = 0.011) and bicarbonate (27.8 ± 1.1 vs. 24.0 ± 0.9 mmol/L, p = 0.071) at baseline. It kept them within clinically acceptable limits (pH ≥ 7.23, pCO2  ≤ 70 mmHg, bicarbonate ≤ 30 mm/L) for ≥120 min of hPACI as opposed to ≤30 min in group one. Fetal pO2 and lactate were comparable between groups and generally within normal range. Fetal brain histology demonstrated fewer apoptotic cells and higher neuronal density in the prefrontal cortex in group two. There was no difference in fetal membrane inflammation, which was mild. CONCLUSION: Fetoscopic insufflation of heated-humidified CO2 during simulated fSB-repair through an exteriorized uterus can be done safely under controlled anesthesia.

Artificial placenta and womb technology: Past, current, and future challenges towards clinical translation.

Extreme prematurity remains a major cause of neonatal mortality and severe long-term morbidity. Current neonatal care is associated with significant morbidity due to iatrogenic injury and developmental immaturity of extreme premature infants. A more physiologic approach, replacing placental function and providing a womb-like environment, is the foundational principle of artificial placenta (AP) and womb (AW) technology. The concept has been studied during the past 60 years with limited success. However, recent technological advancements and a greater emphasis on mimicking utero-placental physiology have improved the success of experimental models, bringing the technology closer to clinical translation. Here, we review the rationale for and history of AP and AW technology, discuss the challenges that needed to be overcome, and compare recent successful models. We conclude by outlining some remaining challenges to be addressed on the path towards clinical translation and opportunities for future research.

Prenatal treprostinil improves pulmonary arteriolar hypermuscularization in the rabbit model of congenital diaphragmatic hernia.

Congenital diaphragmatic hernia (CDH) is a congenital malformation characterized by pulmonary hypoplasia, pulmonary hypertension, and cardiac dysfunction. Pulmonary hypertension represents the major cause of neonatal mortality and morbidity. Prenatal diagnosis allows assessment of severity and selection of foetal surgery candidates. We have shown that treprostinil, a prostacyclin analogue with an anti-remodelling effect, attenuates the relative hypermuscularization of the pulmonary vasculature in rats with nitrofen-induced CDH. Here we confirm these observations in a large animal model of surgically-created CDH. In the rabbit model, subcutaneous maternal administration of treprostinil at 150 ng/kg/min consistently reached target foetal concentrations without demonstrable detrimental foetal or maternal adverse effects. In pups with CDH, prenatal treprostinil reduced pulmonary arteriolar proportional medial wall thickness and downregulated inflammation and myogenesis pathways. No effect on alveolar morphometry or lung mechanics was observed. These findings provide further support towards clinical translation of prenatal treprostinil for CDH.

Maternal-fetal surgery as part of pediatric palliative care.

Maternal-fetal surgical interventions have become a more common part of prenatal care. This third option, beside termination or post-natal interventions, complicates prenatal decision-making: while interventions may be lifesaving, survivors may face a life with disability. Pediatric palliative care (PPC) is more than end of life or hospice care, it aims at helping patients with complex medical conditions live well. In this paper, we briefly discuss maternal-fetal surgery, challenges regarding counseling and benefit-risk evaluation, argue that PPC should be a routine part of prenatal consultation, discuss the pivotal role of the maternal-fetal surgeon in the PCC-team, and finally discuss some of the ethical considerations of maternal-fetal surgery. We illustrate this with a case example of an infant diagnosed with congenital diaphragmatic hernia (CDH).

The artificial placenta and EXTEND technologies: one of these things is not like the other.

The so called "Artificial Placenta" and "Artificial Womb" (EXTEND) technologies share a common goal of improving outcomes for extreme premature infants. Beyond that goal, they are very dissimilar and, in our view, differ sufficiently in their technology, intervention strategy, demonstrated physiology, and risk profiles that bundling them together for consideration of the ethical challenges in designing first in human trials is misguided. In this response to the commentary by Kukora and colleagues, we will provide our perspective on these differences, and how they impact ethical clinical study design for first-in-human trials of safety/feasibility, and subsequently efficacy of the two technologies.

Long-term outcomes of bilateral thoracoscopic T3 sympathectomy for primary focal hyperhidrosis in children.

BACKGROUND: Thoracoscopic bilateral T3 sympathectomy for primary focal palmar hyperhidrosis in children has excellent short-term outcomes. However, data in the literature, on the long-term outcomes of the operation are scarce. METHODS: We conducted a retrospective institutional review of all children and adolescents undergoing T3 bilateral thoracoscopic sympathectomy for primary focal palmar hyperhidrosis between June 2013 and October 2020. We composed a quality of life (QoL) questionnaire evaluating the patient's perception of how much the hyperhidrosis affected their daily life in multiple domains. The questionnaire was completed before the operation and at every postoperative follow-up visit. RESULTS: We operated on 58 patients with a median age of 15 (6-25) years. There were no intraoperative or postoperative complications, and all patients had immediate complete postoperative resolution of their palmar hyperhidrosis. Fifty-three patients (91.4%) had long-term follow-up data available with a median of 2.5 (range 0.1-7.5) years. Two patients (3.4%) experienced recurrence of their palmar hyperhidrosis. Nine patients (15.5%) experienced compensatory hyperhidrosis and required occasional medical management with oral anticholinergics. Two patients reported regretting having undergone the operation. Overall, the mean QoL score improved remarkably, from 42/100 before the operation to 92/100 at 1 month, 89/100 at six months to a year, 97/100 between two and four years, and 80/100 ≥ 5 years after the operation. CONCLUSION: Thoracoscopic bilateral T3 sympathectomy has a high success rate for primary palmar hyperhidrosis in children in the mid- to long-term. Compensatory sweating and recurrence can occur years after the operation, so long-term follow up is mandatory. LEVEL OF EVIDENCE: IV.

Duration of fetoscopic spina bifida repair does not affect the central nervous system in fetal lambs.

BACKGROUND: Prenatal spina bifida aperta repair improves neurologic outcomes yet comes with a significant risk of prematurity and uterine scar-related complications. To reduce such complications, different fetoscopic techniques, for example, with varying numbers of ports, are being explored. This has an effect on the duration of the procedure, potentially affecting central nervous system development. Both the condition and anesthesia can affect the central nervous system, particularly the hippocampus, a region crucial for prospective and episodic memory. Previous animal studies have shown the potential influence of anesthesia, premature delivery, and maternal surgery during pregnancy on this area. OBJECTIVE: This study aimed to compare the effects of 2- vs 3-port fetoscopic spina bifida aperta repair in the fetal lamb model using neuron count of the hippocampus as the primary outcome. STUDY DESIGN: Based on the hippocampal neuron count from previous lamb experiments, we calculated that we required 5 animals per group to achieve a statistical power of ≥ 80%. A spina bifida aperta defect was developed in fetal lambs at 75 days of gestation (term: 145 days). At 100 days, fetuses underwent either a 2-port or 3-port fetoscopic repair. At 143 days, all surviving fetuses were delivered by cesarean delivery, anesthetized, and transcardially perfused with a mixture of formaldehyde and gadolinium. Next, they underwent neonatal brain and spine magnetic resonance imaging after which these organs were harvested for histology. Hippocampus, frontal cortex, caudate nucleus, and cerebellum samples were immunostained to identify neurons, astrocytes, microglia, and markers associated with cell proliferation, myelination, and synapses. The degree of hindbrain herniation and the ventricular diameter were measured on magnetic resonance images and volumes of relevant brain and medulla areas were segmented. RESULTS: Both treatment groups included 5 fetuses and 9 unoperated littermates served as normal controls. The durations for both skin-to-skin (341±31 vs 287±40 minutes; P=.04) and fetal surgery (183±30 vs 128±22; P=.01) were longer for the 2-port approach than for the 3-port approach. There was no significant difference in neuron density in the hippocampus, frontal cortex, and cerebellum. In the caudate nucleus, the neuron count was higher in the 2-port group (965±156 vs 767±92 neurons/mm2; P=.04). There were neither differences in proliferation, astrogliosis, synaptophysin, or myelin. The tip of the cerebellar vermis was closer to the foramen magnum in animals undergoing the 2-port approach than in animals undergoing the 3-port approach (-0.72±0.67 vs -2.47±0.91 mm; P=.009). There was no significant difference in the ratio of the hippocampus, caudate nucleus, or cerebellar volume to body weight. For the spine, no difference was noted in spine volume-to-body weight ratio for the lower (L1-L2), middle (L3-L4), and higher (L5-L6) levels. Compared with controls, in repaired animals, the cerebellar vermis tip laid closer to the foramen magnum, parietal ventricles were enlarged, and medulla volumes were reduced. CONCLUSION: In the experimental spina bifida fetal lamb model, a 2-port repair took 40% longer than a 3-port repair. However, there was no indication of any relevant morphologic differences in the fetal brain.

An Examination of General Surgery Residency Programs with a Rural Track.

BACKGROUND: There is a steady decline in the general surgery workforce in rural areas of the United States. In response, some surgery residency programs have developed rural tracks to encourage rural practice and adequately prepare trainees for this setting. OBJECTIVE: To compare the practice type and location of graduates from general surgery residency programs with and without a dedicated rural track between 2011-2020. METHODS: General surgery residency programs with and without a rural track were identified using the American Medical Association Residency and Fellowship Electronic Interactive Database and the Rural Surgery Program list from the American College of Surgeons. Graduates of these programs who entered general surgery practice between 2011-2020 were subsequently identified from individual residency program websites and tracked to their current practice setting using a Google search of first and last name and residency affiliation. Practice location was identified by zip code or county name and coded by Rural-Urban Continuum Codes (RUCC, Economic Research Service, USDA). RESULTS: We identified 2,582 general surgery residency graduates from 2011 to 2020 across 66 residency programs. Of these graduates from programs without a rural track, 23.6% entered general surgery practice without additional fellowship training, compared to 34.0% from residency programs with a rural track (p = 0.019). Community or University-based program designation was not associated with decision to enter general surgery practice over fellowship training (p = 0.420). Proportion of graduates entering rural practice as defined by RUCC groups 7-9 was not associated with having a rural program track or with community or university-based program status. CONCLUSION: Residency programs with a rural track produce a higher proportion of graduates entering general surgery compared to fellowship, though they are no more likely than programs without a rural track to produce graduates who ultimately practice in rural areas.

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.

Pharmacokinetics and pharmacodynamics of sildenafil in fetal lambs on extracorporeal support.

BACKGROUND: Maternal transplacental administration of sildenafil is being considered for a variety of fetal conditions. Clinical translation also requires evaluation of fetal safety in a higher species, such as the fetal lamb. Experiments with the pregnant ewe are curtailed by minimal transplacental transfer as well as limited access to the fetus. The EXTra-uterine Environment for Neonatal Development (EXTEND) model renders the isolated fetal lamb readily accessible and allows for direct fetal administration of sildenafil. METHODS: Five fetal lambs were placed on extracorporeal support in the EXTEND device and received continuous intravenous (IV) sildenafil (0.3-0.5-0.7 mg/kg/24hr) for a duration of one to seven days. Plasma sildenafil concentrations were sampled at regular intervals to establish the pharmacokinetic profile using population pharmacokinetic modeling. Serial Doppler ultrasound examination, continuous non-invasive hemodynamic monitoring and blood gas analysis were done to evaluate the pharmacodynamic effects and fetal response. FINDINGS: The target concentration range (47-500 ng/mL) was attained with all doses. Sildenafil induced an immediate and temporary reduction of pulmonary vascular resistance, mean arterial pressure and circuit flow, without change in fetal lactate levels and acid-base status. The duration of the systemic effects increased with the dose. INTERPRETATION: Immediate temporary pulmonary vascular and systemic hemodynamic changes induced by sildenafil were biochemically well tolerated by fetal lambs on extracorporeal support, with the 0.5 mg/kg/24 h dose balancing rapid attainment of target concentrations with short-lived systemic effects. RESEARCH IN CONTEXT: None. SEARCH STRATEGY BEFORE UNDERTAKING THE STUDY: A literature review was conducted searching online databases (Medline, Embase and Cochrane), using search terms: fetal OR prenatal OR antenatal AND sildenafil, without time-limit and excluding human studies. Where relevant, investigators were contacted in order to avoid duplication of work. EVIDENCE BEFORE THIS STUDY: Prenatal therapy with sildenafil, a phosphodiesterase-5 inhibitor with vasodilatory and anti-remodeling effects on vascular smooth muscle cells, has been considered for a variety of fetal conditions. One multicenter clinical trial investigating the benefit of sildenafil in severe intrauterine growth restriction (the STRIDER-trial) was halted early due to excess mortality in the sildenafil-exposed arm at one treatment site. Such findings demonstrate the importance of extensive preclinical safety assessment in relevant animal models. Transplacentally administered sildenafil leads to decreased pulmonary arterial muscularization, preventing or reducing the occurrence of pulmonary hypertension in rat and rabbit fetuses with diaphragmatic hernia (DH). Validation of these results in a higher and relevant animal model, e.g. fetal lambs, is the next step to advance clinical translation. We recently demonstrated that, in contrast to humans, transplacental transfer of sildenafil in sheep is minimal, precluding the in vivo study of fetal effects at target concentrations using the conventional pregnant ewe model. ADDED VALUE OF THIS STUDY: We therefore used the extracorporeal support model for fetal lambs, referred to as the EXTra-uterine Environment for Neonatal Development (EXTEND) system, bypassing placental and maternal metabolism, to investigate at what dose the target concentrations are reached, and what the fetal hemodynamic impact and response are. Fetal hemodynamic and metabolic tolerance to sildenafil are a crucial missing element on the road to clinical translation. This is therefore the first study investigating the pharmacokinetics, hemodynamic and biochemical effects of clinical-range concentrations of sildenafil in fetal lambs, free from placental and maternal interference. IMPLICATIONS OF ALL THE AVAILABLE EVIDENCE: We demonstrated self-limiting pulmonary vasodilation, a decrease of both systemic arterial pressures and circuit flows, induced by clinical range concentrations of sildenafil, without the development of fetal acidosis. This paves the way for further investigation of prenatal sildenafil in fetal lambs on extracorporeal support. A dose of 0.5 mg/kg/24 h offered the best trade-off between rapid achievement of target concentrations and shortest duration of systemic effects. This is also the first study using the EXTEND as a model for pharmacotherapy during pregnancy.

Validation of a high-fidelity training model for fetoscopic spina bifida surgery.

Open fetal surgery for spina bifida (SB) is safe and effective yet invasive. The growing interest in fetoscopic SB repair (fSB-repair) prompts the need for appropriate training. We aimed to develop and validate a high-fidelity training model for fSB-repair. fSB-repair was simulated in the abdominal cavity and on the stomach of adult rabbits. Laparoscopic fetal surgeons served either as novices (n = 2) or experts (n = 3) based on their experience. Technical performance was evaluated using competency Cumulative Sum (CUSUM) analysis and the group splitting method. Main outcome measure for CUSUM competency was a composite binary outcome for surgical success, i.e. watertight repair, operation time ≤ 180 min and Objective-Structured-Assessment-of-Technical-Skills (OSATS) score ≥ 18/25. Construct validity was first confirmed since competency levels of novices and experts during their six first cases using both methods were significantly different. Criterion validity was also established as 33 consecutive procedures were needed for novices to reach competency using learning curve CUSUM, which is a number comparable to that of clinical fSB-repair. Finally, we surveyed expert fetal surgeons worldwide to assess face and content validity. Respondents (26/49; 53%) confirmed it with ≥ 71% of scores for overall realism ≥ 4/7 and usefulness ≥ 3/5. We propose to use our high-fidelity model to determine and shorten the learning curve of laparoscopic fetal surgeons and retain operative skills.

In utero adenine base editing corrects multi-organ pathology in a lethal lysosomal storage disease.

In utero base editing has the potential to correct disease-causing mutations before the onset of pathology. Mucopolysaccharidosis type I (MPS-IH, Hurler syndrome) is a lysosomal storage disease (LSD) affecting multiple organs, often leading to early postnatal cardiopulmonary demise. We assessed in utero adeno-associated virus serotype 9 (AAV9) delivery of an adenine base editor (ABE) targeting the Idua G→A (W392X) mutation in the MPS-IH mouse, corresponding to the common IDUA G→A (W402X) mutation in MPS-IH patients. Here we show efficient long-term W392X correction in hepatocytes and cardiomyocytes and low-level editing in the brain. In utero editing was associated with improved survival and amelioration of metabolic, musculoskeletal, and cardiac disease. This proof-of-concept study demonstrates the possibility of efficiently performing therapeutic base editing in multiple organs before birth via a clinically relevant delivery mechanism, highlighting the potential of this approach for MPS-IH and other genetic diseases.

Treprostinil Attains Clinically Therapeutic Concentrations in Neonates with Pulmonary Hypertension on Extracorporeal Membrane Oxygenation Support.

BACKGROUND: TREPROSTINIL IS A PROSTACYCLIN ANALOG USED FOR TREATMENT OF PULMONARY HYPERTENSION (PH) IN ADULTS AND CHILDREN, CURRENTLY AWAITING CLINICAL ASSESSMENT FOR USE IN NEONATES.: OBJECTIVES: WE AIMED TO INVESTIGATE THE USE OF TREPROSTINIL IN NEONATES WITH PH ON EXTRACORPOREAL MEMBRANE OXYGENATION (ECMO) SUPPORT AND MEASURE PLASMA CONCENTRATIONS OF THE DRUG.: METHODS: THIS IS A RETROSPECTIVE CASE-SERIES WITH PROSPECTIVELY COLLECTED BLOOD SAMPLES, CONDUCTED IN A QUATERNARY CARE NEONATAL INTENSIVE CARE UNIT. BRAIN NATRIURETIC PEPTIDE, CARDIAC FUNCTION ON DOPPLER ECHOCARDIOGRAPHY, AND THE OCCURRENCE OF ADVERSE EFFECTS WAS MONITORED. PLASMA CONCENTRATIONS WERE MEASURED USING HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY AND MASS SPECTROMETRY.: RESULTS: FOUR PATIENTS WITH PH REQUIRING ECMO THERAPY WERE STUDIED. TREPROSTINIL DOSES OF 20-58 NG/KG/MIN REACHED CONCENTRATIONS OF 0.99-4.39 NG/ML AND INDUCED CLINICAL IMPROVEMENT. INFUSION OF TREPROSTINIL WAS ASSOCIATED WITH IMPROVED RIGHT VENTRICULAR FUNCTION, REVERSED RIGHT-TO-LEFT SHUNTING THROUGH THE DUCTUS ARTERIOSUS, AND STABLE OR DECREASING NEED FOR VASOPRESSOR SUPPORT. NO ADVERSE EFFECTS WERE OBSERVED: CONCLUSIONS: THIS IS THE FIRST STUDY TO REPORT CLINICALLY THERAPEUTIC TREPROSTINIL CONCENTRATIONS IN CIRCULATING PLASMA AFTER TREPROSTINIL ADMINISTRATION IN NEONATES ON ECMO, WITH ASSOCIATED CLINICAL IMPROVEMENT OF PH AND NO SIGNS OF HEMODYNAMIC INSTABILITY.

Life Support System for the Fetonate and the Ethics of Speculation.

This Viewpoint discusses ethical issues surrounding the use of artificial womb technology for extremely premature infants.