Aug 28, 2018
Dr. Roberta Keller discusses the work of the Pediatric Pulmonary Hypertension Network, (PPHNet) on the network's 10th anniversary. PPHNet is a network of clinical specialists, researchers, and centers bringing a collaborative and multidisciplinary approach to improving care for children with pulmonary vascular disease.
My name is Dr. Roberta Keller. I'm a professor of pediatrics at the University of California San Francisco Benioff Children's Hospital here in San Francisco. I'm a neonatologist, and my primary clinical and research interests is in the evaluation and management of newborns and children with cardiopulmonary disorders.
Today, I'd like to talk to you a little bit about the Pediatric Pulmonary Hypertension Network, or PPHNet.
We are a group of ten centers now, which was originally formed about 10 years ago. We're just celebrating our 10th anniversary. It was really the brainchild of Dr. Steve Abman at the University of Colorado and Colorado Children's Hospital in Denver. He saw a real need to bring together people who took care of children with pulmonary vascular disease and pulmonary hypertension and really tried to combine our experience and our efforts toward learning as much as possible about evaluating and treating children with pulmonary vascular disease and pulmonary hypertension.
So PPHNet originally started with eight centers. UCSF was one of those original centers. One of the things that's really great about PPHNet is that it represents people who care for these children from all different disciplines. Of course, there are pediatric cardiologists, which have been the mainstay of caring for children with pulmonary vascular disease, but also pediatric pulmonologists, pediatric critical care physicians, and neonatologists and really all working together toward the common goal of improving our understanding and treatment of affected children.
One of the great things about that is that we all come from different perspectives and have different ways of thinking about the problems that the children present. Of course, one of the challenges is that we aren't always going to agree on how to approach things or what to focus on specifically. We have some very, very lively discussions around how to focus our efforts. I think really it's been very, very productive because it makes us think about things in a different way, consider other perspectives, and really try to bring all of those view together toward improving the care of these patients through our work.
I think one of the things that's really unique about pediatrics is that we really consider growth and development in all of the decisions we make about children in terms of the state of their disease or condition and whether they could potentially benefit from additional therapies or whether we can potentially start to withdraw therapies over time.
In the adult pulmonary hypertension community and adult cardiovascular community, functional class has always been an important way of thinking about how people function in the setting of their disorder or their condition. If you look at the traditional or standard functional class assessments, those are pretty difficult to apply to certainly younger children, as they have a lot to with people's activities of daily living and when they become short of breath.
Honestly, in children, sometimes that's not even possible to get that history from somebody, whether or not they're short of breath. Their activities of daily living are very different over time. We think about a six-month-old versus a one-year-old versus a three-year-old, that is a constantly changing target. We really like to think about functional class in a way that is more specific to children who are growing and developing and incorporating both developmental milestones as well as nutrition and growth and what's needed for them to have adequate nutrition, and of course finally, whether or not they're able to stay in school and how they function in that environment.
The Pulmonary Vascular Research Institute, or PVRI, several years ago in 2011 published a proposed pediatric functional class, which has really helped us with thinking about these children in terms of their status over time and whether they are improving with their therapies or whether they're stalling out or actually worsening. That's been incredibly helpful.
I think that there's other ways of doing this without formally assigning a pediatric functional class. Those are of course are important, but it really incorporates the things we think about, for instance, related to growth. Are children growing well? Are they not growing well? Somebody who might seem to have stable disease, or even mildly improving disease, by imaging or by cardiac catheterization, may in fact not be growing well. So we decide not to withdraw therapies that we might otherwise withdraw in somebody who had those improving metrics. Similarly, a child who seems to have stable numbers but who is falling off in their growth or development or missing more school, we might decide to escalate therapies in order to try and improve their functional status.
One of the things that we worked really hard on, and I think has been covered before in this podcast, are the guidelines of pediatric pulmonary hypertension. Those guidelines are really a slimmed down version of all the work that we did to try and evaluate all the different aspects of pulmonary vascular disease and the evaluation and management of children with that condition.
I think if you look at the literature now, we see that many people are citing those guidelines, many people are reading those guidelines, and they're really contributing to initiation of evaluation of patients prior to them being referred to comprehensive centers and I hope really contributing to the understanding that many practitioners have of the pulmonary vascular disease and how it contributes to the conditions that the children may have as a lot of pulmonary vascular disease and pulmonary hypertension in pediatrics is actually secondary to other conditions, which is unique I think from the adult population.
We've also looked at a number of these conditions more in-depth and published some papers to help the overall community guide their initial approach to those kinds of patients and also identify what the gaps in knowledge are and what we need to really think about going forward.
Now, in PPHNet, we have been working on a registry. We have almost 1,500 children with pulmonary vascular disease in that registry consented for their information to be included. We're now able to look at those data, of course without any identifying identifiers, but in aggregate, to try and understand how these conditions are presenting variably in different children at different ages and what types of therapies we are using and whether or not we can tell if those therapies are efficacious.
In addition, I think what we see in children in general is that many conditions can actually improve over time with organ growth or development. I think we may be seeing that in the pediatric population that we don't just see the clinical improvement over time or functional improvement over time, but maybe sometimes even resolution because those children are growing new lung tissue and new vascular tissue and really able to improve vastly clinically and come off of their medications.
Now, whether those will be long-term successes or whether they will need to at some point go back on medications, we don't know yet. Obviously, we're all anxious about that and continuing to follow those children very closely. But I think that now with that large registry, we really have the opportunity to better understand these subsets of children in terms of their underlying conditions, in terms of their ages at presentation, in terms of the types of medications that they are initiated on, and medications that are either added or withdrawn in ways that we really never could do before.
I think that there are a couple of things that we really can look forward to in the pediatric pulmonary hypertension community. There is a very, very recent paper that is just now in press looking at how the genetic influences in pediatric pulmonary hypertension differ from those in adult pulmonary hypertension. I think that as we look at those different genetic influences in the pediatric population, we are also seeing differences in things like age of onset of the disorder, and who knows as we go forward and collect more data what other kinds of differences we will see. So I think that these are real opportunities for us to think about how to better tailor our treatment and our follow-up.
There may be certain genetic differences, for instance, that respond better to targeting certain pathways. There may be conditions, as I previously mentioned, that really tend to get better over time. They're others that, of course, may not get better over time. So we will have the opportunity to learn more about that in children by better understanding their genetic background and the setting of pulmonary hypertension and pulmonary vascular disease.
I also think we have a great opportunity to really learn a lot more about medications that we use for pulmonary hypertension in children and how do their pharmacokinetics and pharmacodynamics differ from adults. As a neonatologist, I have a particular propensity toward thinking about newborns, and of course, developmentally many things are changing. Also, their metabolism of drugs changes over time. I think as we see these conditions presenting at birth and are really best trying to understand how to approach intervention, learning more about pharmacokinetics and the pharmacodynamics of medications, different medication classes, and different specific medications in those patient populations will be really critical to trying to optimize outcomes.
My name is Dr. Roberta Keller, and I'm aware that I'm rare.
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