What is bronchopulmonary dysplasia? Discussion of the modes of support, diagnostic criteria, support, wide-reaching impact, prevalence, unique physiology and lifelong risk factors.
All right, so thank you all for being here with us today. I'm really excited to have you all joining in with us. Um, we'll just get started with a little bit of an overview about BPD and why is it that we care so much about this? Why do we dedicate our time to building a program and why are we having an all day meeting about, about BPD? So first I'll just start with what is AVD? So, bronchopulmonary dysplasia is a syndrome of lung injury which disruptsovolarization and microvascular development, as most of the affected infants are born in the canolicular phase of development well before their morphogenesis and alveolar differentiation are completed. And so what we end up with in these babies is really what we call alveolar simplification or just a lower number of alveoli that can participate in respiration. And among babies with severe forms of BVD we see quite a heterogeneity in um their uh lung disease, as you can see here in this panel on the left, there are babies who have um areas very debt consolidation and are mixed with areas of significant hyperinflation. And over the years, there have been several different classification systems used for pulmonary dysplasia. What is the most currently um used and accepted is um the definition put forth by the neonatal Research Network in 2019, referred to often as the Jensen criteria. And this criteria is relatively um, Simple diagnostic criteria which is applied um in infants that are born at less than 32 weeks when they reach 36 weeks postmenculal age and their grade is defined by what type of support they're on. And so the babies that are on Remi no BBD, those that are on 2 L or less nasal cannula as grade 1. Those on non-invasive forms of positive pressure as grade 2, and those that are. Invasively ventilated as grade 3 and we know, and when this classification system was validated, the authors did find that many of the morbidities and things that we worry about such as growth, uh, neurodevelopmental impairment, mortality, and severe respiratory morbidity all increased in a stepwise fast as the severity of the. And so among babies was severe BD. There can be variability in their clinical presentation. And so in this uh in this study done by the team at CHOP, they looked at 72 babies with severe pulmonary dysplasia and classified it based on the types of um physiologies that they found and they found. 78% had moderate to simal disease, 66% had pulmonary hypertension, and 60% had large airway disease. But the most common phenotype across the group was that in about a third of them, they had all three of these components present. And then we also know that babies with um severe BPD have a higher risk for neurodevelopmental impairment. And so when looking at um Bailey spores indicating severe um severe impairment, those with grade 3 BVD had uh had 40 or 40% of them were affected by severe. And so, going back to, you know, why is BBD so important for us to to um study and to um You know, to work towards improvement for. And for one, we know that it's a very uh prevalent problem in babies that are born in the extremely premature um category. So among babies born less than 27 to 28 weeks, as many as 60 to 70% of babies are affected by BBD and 30% in that group are affected by severe BVD, so growth rates 2 to 3. And also we know that it can have a lifelong impact. And while most of these kids are able to get better over time, and we see quite dramatic transformations from being very fragile, extremely premature infants through an evolving phase and a stable disease, and finally to a very thriving state, which is very rewarding. We do know that in adulthood, these, these children. Develop or as they become adults, they are at risk for a more rapid and um significant decline in respiratory function of adults. So it is something important across all ages. And because of their unique physiology, there are a number of challenges that we face while they're with us in the hospital. And some of those include challenges of their medical management and team dynamics, um, challenges relating to supporting the infants and addressing their developmental needs while avoiding discomfort and harms that can't come just with being in an ICU setting, and also the impact of families is, is huge, so they go through a lot of socioeconomic and emotional impacts that can be um. You know, because they're in the hospital for quite a long time and can be very devastating to some families. And so while we are learning exponentially about etiology, um, treatment, and, and long-term outcomes of these babies with, um, there are a few important lessons that we have learned in the last several years that I would just like to briefly share with you. So one is that lung injury and physiologic changes occur early in the postnatal course. And so, even by a month of age, we can see that there are changes that have already happened that may require um a change in our support strategy. The group at Nationwide Children evaluated respiratory severity score, which is the product of the median of pressure in the um FIO2 um at Day of Life 30 and found that it was predictive of mortality and, and longer duration of mechanical ventilation need. And also we've learned from the group at Riley Children's in which they have a BBD consultation service that starts seeing babies as early as 28 days if they're still remaining on invasive support. The physiologic assessment and ventilator assessment of those babies even that early may has in their context reduced the need for tracheostomy and their and their lemp of state. And we've also learned about how management can affect their outcomes, and um many And institutions have started instituting chronic phase ventilation strategy which addresses the altered lung physiology as well as supporting the growth of metabolic states and have report, um, there have been several single center studies that have reported improved outcomes with this, um. Um, type of intervention, and we also see that in general survival for severe BPD is improving over time from historic rates in the 75 to 80% range in the 1990s and 2000s to now over 95% to initial discharge among our collaborative cohort. And I just wanted to show a few examples in the next slides of how we've seen some of these management strategies make a difference. And this is a report again from Nationwide Children's in, in which they look at their infants that were referred late, so after 36 weeks with established BPD who had a pretty high severity of illness. And they were able to show that within 4 weeks' time, the respiratory severity score decreased by 27% um in those patients who are who survived. And in fact, despite having a very high um severity of illness, they'd have 92% survival in this pill h and what they concluded from. Um, this experience is that they're targeted respiratory support strategies that address the physiologic needs and, um, specifically aiming to optimize ventilation for fusion matching and allowing emptying of obstructive disease, lung compartments was what was very um influential in having this great outcome. And we also know that growth and nutrition is, is really important, and gains and lung function have been correlated to gains and linear growth, and also better nutritional measures have been shown to correlate with improved neurodevelopmental outcomes. And you know, that's another reason why we are always talking about nutrition for these kids and ensuring that we're giving the right micro and macronutrients and vitamins to give them what they need to be able to um improve their growth. But also we need to pay attention to barriers including trying to avoid hypermetabolic states and, and factors that contribute to growth suppression. And you might not think that um the things that we do for these babies every day is a big deal, like waking them up on their sleeping and poking them for labs or, you know, doing other procedures in the room. But all of these noxious stimuli can create um a sense of chronic stress in these babies that can increase their cortisol levels and impair their optimal growth. Another thing that we've learned is that interdisciplinary care teams really are important and they can improve outcomes, and there are, these are just a few that that I've shared, but there are even more out there now about how implementation of these programs can improve neurodevelopment, lead to fewer rehospitalizations, improve survival, improve length of stay, growth, and lower rates for trachea. And so some of these things we've learned impacted out here up to this point. Uh, so, as I mentioned, indisciplinary care teams, you know, we, as a group around the country and, and internationally that, um, are focused on care for babies with BVD, we recognize that interdisciplinary care teams are really important, um, in the sense that they promote teamwork, collaboration, and, and engagement and also allow us to learn from one another. And we're proud to have been able to put together our BPD team here which allows us to deliver better care and to engage in more research and quality initiatives. And one of our missions is to educate, um, educate others in our community and, you know, outside of our hospital as well as all levels of, of care within our own hospital. And so we hope that this conference today helps to achieve some of those goals. Um, Another, um, The way that we, you know, aim to optimize care is by um implementing a chronic phase ventilation strategy and in doing this, it really allows the baby to breathe comfortably so that we can shift our focus from just breathing to supporting their growth and their development. So we are also fortunate to be members of the Bron pulmonary dysplasia collaborative, collaborative, and um this formed in 2012 as a group of seven centers who were dedicated to improving the care for babies with the most severe forms of BPD and um. Now we are up to, I think almost 50 members, uh, 50 member sites. Part of participation in the collaborative is not just sharing with each other anecdotes or cases, but also, um, all sites enter data into a registry, and that registry, uh, allows us to be able to, uh, collectively publish our experiences and, and look at various, um, aspects of that theory. And, you know, I've already mentioned it several times, but the interdisciplinary care model is, is really um vital to delivering the best care for these babies, and you can see here I've listed many of the team members that participate, not just here in our group, but in other in other centers as part of their um Their way to care. And we know that everyone comes from with a unique perspective on a particular on their particular specialty of care, and that when we really listen to each other and focus on the needs of the whole baby rather than our individual organ system that we can really do better for the babies. And I've referred to it a few times already, but um, You know, ventilating, and oxygenating patients is, is different than what is typically um considered to be the norm in neonatology, and the difference is because the, as the lung physiology changes over time, the needs are different. Right. And so in the early phases of uh ventilating extremely pre-terms, we're typically dealing with a more homogeneous type of lung disease in which the compliance and resistance is relatively similar throughout the lung. And in this, um, phase of disease, using low tidal volumes, faster rates and lower infantory times, um, is adequate and even. You know, best practice for avoiding lung injury. But when a baby begins to have evolving or established BPD and they're developing areas of large heterogeneity, these babies need larger tighter volumes starting in the range of 10 to 12 mL per kilo and may even need higher depending on the severity of the disease. They need longer respiratory times, typically greater than or equal to 0.6 seconds. And they need slow rates to allow for better emptying of these larger tidal lungs, and typically they need higher peep in the range of 0 starting, but some are even in the mid-teens by the time we figure out exactly what they need for um optimal lung mechanics. And The other thing that we need to remember in these in these situations is that the changes that we made in the support are all really interdependent, so you can't just increase the higher volume, but leave a higher rate because that will lead to more long hyperinflation and air traffic cause the baby to be more uncomfortable and hyper. And we also aim to keep the oxygen saturation targets at least 92% to um prevent or uh slow or prevent or improve um pulmonary hypertension in these children. Um, This is a figure that is used many, many times when giving talks by multiple people because it's just very um illustrative, um. How these different lung or how these different ventilator settings can really benefit the patient. And so, um, on the left here in panel A, we're looking at um a lung. Well, same on both sides here, but there are areas of different physiology. Some with low compliance and high resistance, others with high compliance, low resistance, and others that are relatively normal compliance resistance. And when we are using a low tidal volume and faster rate strategy, we may really be only. Um, utilizing a very small portion of the lung, that part of the lung that is still healthy becomes the part that is really, um, what the baby is living on, and that leads to worse distribution of gas, higher dead space, higher, um, PCO2 and FIO2 requirements, aileticis and regional overextension. But when we switch our strategy to using the higher volume and longer inspiratory times with a slow rate, we do, we are able to use more of these segments of the lungs, and this can lead to better gas distribution, low less dead space, better ventilation, lower altitude requirement, and less lysis. And so when we're using um ventilation and this chronic phase of support, we're not just looking to have a pretty blood gas, and in fact, We don't check blood gassess very much at all. What we're really looking for is that the baby is developing respiratory stability and that they're able, we're able to shift their focus to development and, and other um achievements, and we look to see that they're coming down on their IO2, that they're having fewer spells, that they're tolerating cares and handling, needing less sedation. And also, um, part of our goals in in this are to prevent the development or progression of pulmonary.
