Dr. Mike Smith (Host): This is Transformational Pediatrics. I'm Dr. Mike. And with me is Dr. Ekta Patel and Dr. Devon O'Brien from Children's Mercy Transformational Pediatrics. Today, we'll discuss CDH in our panel discussion. Let's go ahead and start with Dr. Patel. What is CDH? Give us a nice rundown of what it is, how common it is, and what makes it so complex for families and care teams.

Dr. Ekta Patel: Yeah. Well, thank you for the invitation. We're excited to be here. And CDH stands for congenital diaphragmatic hernia, and it's a relatively rare condition. We see it in about one in three to 4,000 live births annually. However, as a referral center here at Children's Mercy, we care for a lot of pregnancies with this diagnosis.

What CDH is is it's a defect in how the diaphragm forms, which allows those intestines to herniate into the chest; and therefore, impeding lung growth. About 85% of the time when the hernia forms, it's usually posterior in the back and on the left, which means that the heart can get shifted to the right and actually compress the right lung as well.

Dr. Devon O'Brien: There is diagnostic complexity that leads us to challenges for both families and our care teams. CDH doesn't always look the same. The diagnosis can range from mild to severe, depending on how large the defect is. And therefore, there can be a wide range of potential outcomes.

A lot of this depends on how much of the fetal lungs are able to grow and develop normally, which can be difficult to fully predict prenatally. There are multiple imaging modalities that can be utilized during pregnancy to better understand prognosis and guide management. However, we often don't learn the true extent of the neonatal impact until the time of birth.

Dr. Ekta Patel: That's right, Dr. O'Brien. These prenatal complexities really make it difficult to predict their postnatal course and following delivery. We know that there's a potential to cause severe respiratory issues, but this is not just because the lungs aren't able to grow, but also because the lung vessels grow abnormally as well. And this leads to pulmonary hyperplasia and pulmonary hypertension or high pressure in the lungs. Because of these interactions, that management of CDH really requires a strong multi-disciplinary collaboration.

Host: And Dr. O'Brien, what typically raises the suspicion for CDH on prenatal imaging and how do you assess severity once it's identified?

Dr. Devon O'Brien: So, CDH is usually suspected during an ultrasound when we see the abdominal organs, for example, intestines or stomach up in that chest. So, the heart often will also be deviated off to the side, which is another clue that there are or can be additional organs in that fetal chest cavity. Sometimes the defect in the actual diaphragm can be evident in some of our views on ultrasound. So once we suspect the diagnosis, the next step is to further characterize the size of the defect, the organs that are being herniated, the amount of normally developing lung tissue that's there.

For example, if the liver is herniating into the chest cavity, this is usually classified as more severe. Specifically for the lungs, we would look at the observed to expected lung-to-head ratio, or OTELHR for short. This is a percentage representing a measurement of the contralateral lung area or the side opposite from where that hernia is in comparison to what we would normally expect to see at that gestational age.

Lower percentages would generally indicate a more severe CDH and, therefore, a worse prognosis. An MRI performed as the pregnancy progresses can also be a really useful tool in accurately calculating these percentages, and therefore help us to better predict outcomes.

Host: So Dr. O'Brien, sticking with you for maternal-fetal medicine colleagues that you deal with, what does this referral process look like and at what stage are you, the specialist, actually seeing the patient?

Dr. Devon O'Brien: So, we would recommend that a referral will be placed as soon as a CDH is suspected. So ideally, that would be before 24 weeks' gestation. Because of the complexity of the diagnosis, there are multiple layers to the evaluation, which includes detailed ultrasound, fetal echocardiogram, as well as coordination with a large multidisciplinary team.

And additionally, there's actually the potential for fetal intervention in specific circumstances and severe cases. So, this window of opportunity is really time-sensitive. There are specific fetal centers that can offer this fetal intervention, and it is important to coordinate delivery at a hospital that can provide advanced neonatal support.

Host: And how many hospitals in the United States are able to do this? Do you have a number or do patients often have to travel to a specific hospital?

Dr. Devon O'Brien: So I don't have that specific number, right now, but I do know that it really depends on the area of the country that you're in. And there are plenty of when patients do have to travel very long distances to be able to be evaluated and undergo this fetal intervention.

Host: Well, so now that a patient has been referred, can both of you kind of walk us through the multidisciplinary pathway? I know there's a lot involved here. It's complicated. You got the fetal health center consultation, delivery planning, NICU, surgical repair. Just kind of walk us through how this is all going to work.

Dr. Devon O'Brien: So as you mentioned, there is a lot that goes into the evaluation and that delivery planning and beyond. So, the first step from a maternal fetal medicine standpoint is to meet the patient, get a full history, and perform that very detailed ultrasound, because we then use that ultrasound to go ahead and initially calculate that OTELHR percentage that we talked about and understand if the liver's above or below the diaphragm. That lets us to start to characterize the severity of the CDH. And during this time, an amniocentesis or procedure to genetically test the amniotic fluid may be performed based on the clinical situation and potential for fetal intervention. We also want to make sure that that patient gets scheduled for the fetal echocardiogram with pediatric cardiology and coordinate consultations as a part of that large conference to include a multidisciplinary team with pediatric surgery, neonatology, palliative care, maternal fetal medicine, social work, and genetic counseling.

In general, an MRI is recommended around 28 weeks' gestation or sometimes earlier if prenatal intervention's being considered. From there, we would decide if the patient is a candidate for any prenatal intervention. But regardless, we would want to schedule frequent ultrasounds and fetal monitoring for the remainder of the pregnancy. Delivery timing will ultimately depend on many maternal and fetal factors, but the goal will always be to safely prolong the pregnancy and avoid prematurity.

Dr. Ekta Patel: Well, then, that's where our team kind of comes into play, where after the baby's born, our immediate goal is to stabilize the baby. And we place a breathing tube or procedure called intubation to avoid distension of those abdominal contents, which can further compress the lungs. We want to watch the baby carefully as they transition from being inside mom to being on the outside, and we closely monitor saturations or how their body's receiving oxygen and how they're perfusing their body. We want to obtain some vascular access to be able to further evaluate the baby and provide some sedation, because we want these babies to be really comfortable and allow the ventilator to do its job, and have minimal stimulation to prevent aggravating that pulmonary hypertension.

The optimal timing of surgical repair continues to be debated, but the current standard approach is to delay repair until the baby has reached physiological stability. There are various patient factors, which includes severity of that pulmonary hypertension and the responses to the medical therapies that really significantly influence that decision of when surgery is appropriate.

However, there's always those cases of the babies when they have severe CDH and they have severe respiratory failure and/or refractory pulmonary hypertension where our highest level of support called extracorporeal life support or ECLS is needed to rest the heart and lungs. And then, when this happens, our institution will repair the hernia about 24 hours after being placed on ECLS.

Host: So, I want to open up this question to both of you. I'd like to hear your opinions. What does thriving look like for CD-8 survivors? From feeding, growth, neurodevelopment even followup. How do you define success in thriving here?

Dr. Ekta Patel: Well, we really learn about CDH every day, and we're gaining new insights into the therapies that really go into their cardiopulmonary, neurodevelopmental, musculoskeletal, nutritional, gastrointestinal, all these things that kind of really play a role into the CDH. And the severity and the prevalence of outcomes are so variable and it changes as the kids get older. So, really thriving depends on each baby.

The CAAP recently published guidelines that stratify these patients and help us provide guidance and resources to support the quality of life throughout their lifespan. And at Children's Mercy, we're privileged to have a comprehensive clinic called the Neon Clinic, which stands for Neonatal Evaluation and Outcomes Network, that coordinates all of these cares for these babies.

During these clinic visits, the team is comprised of neonatologists, pediatric surgery, cardiology, nutritionists, social workers that all kind of coordinate all these aspects of the baby to help them thrive.

Host: So looking ahead, what feels the most transformational in CDH Care right now? And specifically, how is Children's Mercy transformational?

Dr. Ekta Patel: Well, we've always had great outcomes for our infants with CDH at Children's Mercy. But we know that standardizing care leads to even better outcomes. So about a year ago, we created a guideline to help streamline the management amongst our providers. And then, one of the hot topics that's really in CDH care is to identify what pulmonary hypertension phenotype that the baby is presenting with and using that to help tailor our therapies based on how that cardiopulmonary interaction is evolving.

So, we'd work with our cardiologists to obtain a targeted echo to help us identify and best manage these babies. And then, advances really continue to evolve. And there's research focusing on biomarkers that help identify severity and regenerative medicine approaches to improve fetal lung development and other studies that look to optimize postnatal outcomes.

At Children's Mercy, we're looking at how to potentially further improve our delivery room management and other research that investigates the best practices for when babies do require ECLS.

Host: Dr. Patel, do you have any thoughts on what's transformational right now?

Dr. Ekta Patel: Well, it's a really exciting time and one of the most fascinating advances in our patients is a procedure called FETO or fetoscopic endoluminal tracheal occlusion. And since that's kind of one of the things that Dr. O'Brien will specialize in, I'll let her kind of explain that for you.

Dr. Devon O'Brien: so as Dr. Patel said, it really is exciting that this procedure and the research surrounding it is ongoing. It really is a procedure where a balloon is placed in the fetus's trachea to temporarily block that trachea, and therefore that will stimulate the underdeveloped lung to grow bigger before birth and hopefully preventing, or maybe even reversing that pulmonary hypoplasia, therefore improving outcomes for these babies.

 The early results from this are promising, and we are excited for when we will, again, be able to offer that to our patients at Children's Mercy.

Host: That sounds fascinating. And I look forward to hearing the future success of the procedure. I want to thank you both for coming on today. This has been a fascinating discussion about CDH. And I know that the audience is probably wanting to talk to you guys and learn more about it. For more information, you can go to childrensmercy.org/departmentsandclinics/fetalhealthcenter.

If you enjoyed this podcast, please share it on your social channels and explore our entire podcast library for more topics of interest to you. This is Transformational Pediatrics. I'm Dr. Mike. Thanks for listening.