#458 - [Journal Club] - 📌 Can the respiratory severity score show us where a baby is heading?

The respiratory severity score is one multiplication most of us already do in our heads, mean airway pressure times FiO2. This week Dr. Dinushan Kaluarachchi joins Journal Club to walk through three papers built on it, RSS trajectories across gestational age in the PROP cohort, an RSS based grading of BPD at 36 weeks, and RSS after 40 weeks as a predictor of tracheostomy. He also talks about writing that last paper with his son, a high school junior, and why a brief communication is a realistic on-ramp for students. Plus a preview of two upcoming trials, including surfactant given through a supraglottic airway.

https://www.nature.com/collections/ejaffajdhi

----

Bronchopulmonary Dysplasia Definition Based on Respiratory Severity Score. Kaluarachchi DC, Peebles PJ, Lasarev MR, Guthrie SO, Laughon MM.Pediatr Pulmonol. 2026 Jul;61(7):e71750. doi: 10.1002/ppul.71750.PMID: 42478108 Free PMC article. No abstract available.

Respiratory severity score patterns by birth gestational age among a cohort of extremely preterm infants. Peebles PJ, Lasarev MR, Guthrie SO, Laughon MM, Keller RL, Kaluarachchi DC.J Perinatol. 2026 Jun 29. doi: 10.1038/s41372-026-02778-8. Online ahead of print.PMID: 42374145 No abstract available.

Respiratory severity score as a predictor for need for tracheostomy in infants with severe bronchopulmonary dysplasia. Kaluarachchi NM, Afah Annah S, Lasarev MR, Peebles PJ, Kaluarachchi DC.J Perinatol. 2026 Jun 25. doi: 10.1038/s41372-026-02720-y. Online ahead of print.PMID: 42350618 No abstract available.

Transcript

Ben Courchia, MD (00:00.614) Hello, everybody. Welcome back to a special edition of Journal Club on a Friday. Daphna, good morning. How are you? Happy to be here as well. We are joined in the studio by a physician who has, I guess, become a friend of the show, friend of ours, Dr. Dinushan Kaluarachchi from the University of Wisconsin. Dinushan, welcome to the show. Welcome back to the podcast.

Daphna Yasova Barbeau, MD (00:07.578) Good morning, good morning. Happy to be here.

Dinushan Kaluarachchi (00:27.8) Yeah, thanks for having me. It's my pleasure to be here.

Ben Courchia, MD (00:31.196) We have a lot of ground to cover today, so I'm gonna try to stay organized. You are behind the publication of three papers published on the concept of respiratory severity score. There's a letter that is open access in Pediatric Pulmonology called "Bronchopulmonary Dysplasia Definition Based on Respiratory Severity Score." There is a comment

published in the Journal of Perinatology called "Respiratory Severity Score as a Predictor for Need for Tracheostomy in Infants with Severe Bronchopulmonary Dysplasia," whose first author is none other than Nathan, your son. And so that's gonna be exciting to talk to you about. And then a brief communication, again in the Journal of Perinatology, called "Respiratory Severity Score Patterns by Birth Gestational Age Among a Cohort of Extremely Preterm Infants." So I'm gonna burst everybody's bubble. We're not gonna have time to review all three papers

on the air. So you need to go and read them. They're very nice, very easy to read. But I'm going to ask you some questions so that we can actually cover a little bit of what these three papers really add to the body of evidence. So the first thing, I guess, Dinushan, is can you tell the audience who are not familiar, what is the respiratory severity score? What is it? How do we calculate it? And what is it a marker of?

Dinushan Kaluarachchi (01:53.268) Yeah, no, it's a great question. So respiratory severity score, or we call it RSS, it's an illness severity score for the respiratory disease in preterm infants, or any patients for that matter. So basically what it is is mean airway pressure times the fraction of oxygen. So MAP times the FiO2. For instance, if we have a baby with a mean airway pressure of 10 and FiO2 is 40 percent, so that's 10 times 0.4, which is four.

So we have been using this in a number of studies. So this is the more recent data that we published. But in the past we have used it as a predictor for CPAP failure in the first couple of hours of birth. And then we have used this in some of our clinical trials that we are doing also. So the way I look at it, when we talk about the FiO2, which most of the studies are using, you're only looking at one aspect of the illness severity. But when you look at the mean airway pressure

times the FiO2, that gives more of a bigger picture how the baby's doing respiratory wise.

Ben Courchia, MD (02:59.1) Yeah, and it's something that we inherently do at the bedside all the time. You look at how much pressure you're using to actually maintain the patient in a stable state. You're looking at how much FiO2. And the respiratory severity score is obviously very much influenced by the neonatologist. You determine how much MAP you want to give, you determine how much FiO2. But I think that for the most part, as clinicians, none of us are using more than we need. I think at the end of the day, we're all trying to aim for the lowest amount of support to maintain

to maintain a hemodynamic stability. Going back to the score, I think it's important for people to have a mental map of what that looks like. So at the end of the day, when you think about it, it can go as low as zero point whatever, this can be very low. And in terms of the highest respiratory severity score you can get, you might get in the teens. If you have a baby on a mean airway pressure of 12 and an FiO2 of 100, then that's gonna be 12. And once you're at 100%,

then your mean airway pressure is going to determine your respiratory severity score. And these are going to be the highest. I don't think that anybody can ever compute a respiratory severity score that's going to exceed 17, 18, or something like that. And if you are, you probably don't need the respiratory severity score to tell you that this is not a good situation.

Dinushan Kaluarachchi (04:10.955) Yeah, yeah. No, exactly. I think, for instance, if a baby's on room air we assign a zero of RSS, and then the highest we have seen in our data set was nineteen point two or something like that.

Ben Courchia, MD (04:25.552) Yeah, there you go. There you go. So what you're achieving with these three papers is very interesting. So I want to start maybe with the Journal of Perinatology brief communication that you looked at, because basically what you did is leverage data from the Prematurity and Respiratory Outcomes Program, PROP, in order to identify what are some of the patterns of how those RSS evolve for babies that are born

between 23 and 29 weeks of gestation at 13 different sites. And what you have is figure one, which, by the way, I think two out of these three papers have phenomenal figures. Congrats on that. Where basically we look at the respiratory severity scores based on the completed postmenstrual age. And what the paper basically says, and I'm paraphrasing and it's a very limited

conclusion, but basically we see that when it comes to this particular process, the respiratory severity score increases within the first two weeks of life, followed by a gradual decrease throughout the study period. Kind of what we're used to,

knowing that usually in the first two weeks of life respiratory morbidities are the most common cause of mortality for these infants. So it's not surprising. But it does put it into view, and the graphic is very eloquent. So anything else that you would like to add about specifically this outcome?

Dinushan Kaluarachchi (06:07.425) Yeah, I just wanted to say those graphs actually do look great in color, which we were unfortunately printing in the journal. But basically the idea came, so there are studies looking at the FiO2 patterns, there are studies looking at the respiratory support patterns, but that only tells one side of the picture. So we thought a global view of the respiratory status would come from RSS.

Ben Courchia, MD (06:13.646) Yes.

Dinushan Kaluarachchi (06:34.513) And one thing about this data set that we acquired, the PROP cohort, which is a phenomenal data set, what they did was they recorded the respiratory settings the babies were on every single day at 12 noon. So that's very standardized. So we were looking at the data set and trying to figure out things that we can do, and then we thought this is a data mine, a great source of data, like in

each individual day you have the respiratory support settings at a dedicated time. So that's kind of how we ended up calculating the RSS and graphing it out. And then we were thinking about, how can we use this? I mean, definitely this is information that is great for the clinicians at the bedside and also to the families for family counseling, and also

Ben Courchia, MD (07:10.033) Yeah.

Dinushan Kaluarachchi (07:27.665) we were thinking about, how can we use this data? So this would be great data for entry criteria for clinical trials, for instance. And then two of the other ideas that we came up with, can we use this data to predict need for tracheostomy? So that's where we ended up doing the second paper. And then we looked at 36 weeks specifically to define a BPD grading system based on the RSS.

Ben Courchia, MD (07:54.386) Yeah, I'm gonna mention that last piece first, because it's very interesting. You looked at, could we use RSS to define babies based on clinical BPD diagnosis? And you basically use that in comparison to what is known as the Jensen criteria. But basically saying, hey, what if we could classify, categorize respiratory severity scores? You have a respiratory severity score of zero, you have no BPD. Maybe an RSS score like

0.25 or less, and this is your grade one. An RSS score of 0.26 to 0.64 would be grade two, and an RSS of above 0.65 would be a grade three. And I think it's a very clever idea, because obviously we've looked at different BPD definitions. Some of them use FiO2. Jensen uses kind of an indirect way of looking at delivered mean airway pressure, because obviously you have low flow, high flow, and non-invasive and then invasive.

But it does do quite a good job. And transitioning directly into the tracheostomy conversation, you can see that specifically after 40 weeks of gestation, how RSS can be a very nice measure of who predictively might need a tracheostomy or who's at risk of mortality, even. I think that this is key. And

in my opinion, this last paper that you authored with your son is very interesting for discussions with family, because, like we always say, we've been caring for these babies all the way through forty, forty one weeks. And we somehow always believe if I wait another week, this baby is going to be a different individual. But sometimes when you see these types of data, you're like, you know what, sometimes the safest thing to do might be the right thing to do. So I think this is very, very interesting data for sure. Have you guys started

leveraging RSS at the University of Wisconsin, and or maybe not as a unit, but even individually as a clinician, in how you approach patients and maybe discussion with families?

Dinushan Kaluarachchi (10:00.438) Yeah, to some extent. I mean, we are starting to use it. So the way I say it, RSS, because it's an objective marker, and then you look at the trend week to week. So that's a nice way to look at the progression of the respiratory illness, whether it's getting better or is it getting worse? So at the moment we actually use the Nationwide trach tool, which I think is a great tool as well. But the problem with that is

it is so comprehensive that it's difficult to use at bedside.

Ben Courchia, MD (10:34.237) Yeah, you need to sit down, and I use the tool as well. You need to sit down in a room and spend fifteen minutes to score the babies.

Dinushan Kaluarachchi (10:40.353) Yeah, yeah. So which is a great tool. I'm not denying any credit to the Nationwide group. We also use it, but we are hoping to come up with something simpler, something that you can use at bedside without a ton of input, but not just the RSS, but incorporate the other aspects of care, especially the developmental piece, developmental scores. So something

Ben Courchia, MD (11:07.741) You've got to make an app.

Dinushan Kaluarachchi (11:09.749) Yeah, I mean ultimately that would be the goal. So we just had several conversations about this just a couple of weeks ago, because we figured out we have some babies that definitely should be in the conversation, but according to the Nationwide tool they are in the green zone, which I don't think is right. So

Ben Courchia, MD (11:12.605) Please.

Ben Courchia, MD (11:30.983) So for the people who may not know, the Nationwide tool divides babies into green, yellow, red. Red, if you land up on red, you're most likely gonna need a tracheostomy. In between, you're in yellow, which means your course might evolve, you need more time. And green, meaning you are at a low risk of needing a tracheostomy in the near future.

Dinushan Kaluarachchi (11:51.938) Yeah, exactly. So our hope is to use this. This is basically hypothesis generating data, but we definitely can use this idea and incorporate some of the other aspects, collaborate with other sites and potentially have a more prospective study, and then come up with a score, validate the score, and then eventually use it for clinical use.

Ben Courchia, MD (12:15.602) Mm-hmm.

Ben Courchia, MD (12:20.156) Daphna, you're muted.

Daphna Yasova Barbeau, MD (12:22.562) No, I guess my question that I have about all of the papers and the use of the respiratory severity score is, when are you starting to introduce this to families? Is it something that you're discussing as a team, kind of a team-based approach for decision making? How often do you reassess with a team and with the family? I think we're all facing these decisions about when to broach

topics about transitions of care for these types of babies.

Dinushan Kaluarachchi (12:58.625) Yeah, no, that's a great question. So we talk about it during rounds, during our clinical conversations with the families and with the other colleagues as well. But I want to admit that we don't use it that extensively in the clinical care. So this is still in the developmental stages. Where we actually use this is in a very different setting. So the idea of all this came from some of the

aerosolized surfactant clinical trials that we did. We had multiple sites across the United States, and some start with a CPAP of four, they only go up to six, and then there are other sites who start on CPAP of 10. And then because we have all these sites and all these different uses of CPAP, we had to come up with some criteria, like what would be the entry criteria to the study?

What would be the CPAP failure to administer surfactant? Because this was very different between the sites. So that's actually how we started using the RSS in the clinical trial setting. So we conducted an industry trial called AERO-05, which is the aerosolized surfactant trial, calfactant. And we used the entry criteria to be 1.25 and higher, up until 2.4. And then

we had certain criteria to administer surfactant, liquid surfactant, if the baby had CPAP failure. So that's one way we use this score in particular. But definitely it has value in the clinical care, and people are starting to use it. We are not using it day to day, but we definitely have that in our conversation.

Ben Courchia, MD (14:46.312) So my next topic of conversation really focuses on working with your son. I feel like for a lot of us, we are parents of children who are in their teenage years, and I think that the prospect of doing some form of collaboration is something that we would all like to do. And I'm curious, how hard was it to get this done basically, to get your son involved in this project and really take something from

from ideation to publication.

Dinushan Kaluarachchi (15:18.507) Yeah, no, it was great working with my son Nathan. He's a junior here at Middleton High School. He's very interested in science, and also he writes for the school newspaper. So he's definitely a great writer and definitely is interested in pursuing a career in science. So he actually worked with the daughter of

Ryan McAdams, one of my colleagues, whom you guys know, Moriah McAdams. They actually worked on, it's through Pediatric Research, it's a science letter, a kid's science letter, essentially they're breaking down a research article. So they worked on that, and Nathan was very interested in pursuing something, because he actually reads a lot of stuff.

Ben Courchia, MD (15:50.386) Yeah.

Dinushan Kaluarachchi (16:17.296) So we had these ideas, and I had an undergraduate student working with me at the time. His paper is not published, he presented at PAS, that hopefully will come in the next few months or so. And I initially had him work with this undergrad student. His name is Samuel. And then he wanted to work on his own project. So we used this data set, because this is already collected data. I mean, a lot of

kudos to the PROP cohort investigators. And we sat down with our team. I worked very closely with Patrick Peebles, one of our other neonatologists, and the study statistician, and we talked about the idea, kind of how to approach this, things of that nature. And then, because the data is already there, the study statistician analyzed the data, and then we had several other meetings to kind of discuss the data and eventually write it up.

He presented this at the Midwest SPR in Chicago and then eventually at PAS. And then this mechanism of brief communication or research letters, I think it's very, very useful, especially for undergrad students, high school students, even for some pediatric residents, because basically it's a little extension from a PAS abstract. So it doesn't involve a huge undertaking.

It's something that you can get done in a fairly easy way, in a fairly reasonable time frame. So no, it was a great experience. He learned a lot in the process. So did Samuel, the undergrad student. And it was great to collaborate with him and have this paper.

Ben Courchia, MD (18:05.832) Yeah. Samuel, who's the second author on the paper. How was it for you? Did he frustrate you or did he make you proud?

Dinushan Kaluarachchi (18:12.596) No, he definitely made me proud. He's a great kid. He's really interested in these type of topics, and he was very hands on involved in the study. No, definitely proud of him.

Ben Courchia, MD (18:27.294) So for the people like me who have children who are, whatever, thirteen to nineteen or something like that, is this something you would recommend, to try to find avenues where there's an opportunity to have parent child collaboration on meaningful scientific work? Obviously if both parties are interested, that goes without saying. But is that something? Yeah.

Dinushan Kaluarachchi (18:48.084) Yeah, definitely. If that's something the child wants to do, I mean, he's definitely very motivated, very enthusiastic about the study. So definitely, if they are involved and if you have something reasonable. So you can't really have them do a huge project, a complex project. This is a really easy concept to understand. Some of the babies, little babies, will have lung disease,

some of the babies will have bad lung disease that they would need a trach, and we have to come up with different ways to identify these patients in a reasonable timeframe. So that was a kind of easy to digest idea, and it's easy to conduct the study because the data was already available to us. So

Ben Courchia, MD (19:34.42) Yeah, that's the key, right? Number one, the data is well collected already. So that saves a huge amount of work from trying to train someone to do that. But like you said, also the concepts are not very difficult to grasp, and you can explain a couple of things and suddenly whoever you're working with is up to speed, rather than saying, my god, I have to spend three weeks explaining everything before we can even understand. I think this is right. The combination of

solid data and concepts that are quite graspable is key, in my opinion, for anyone who's trying to follow in your footsteps.

Ben Courchia, MD (20:18.205) Yeah. Okay. Daphna, any parting thoughts?

Daphna Yasova Barbeau, MD (20:23.344) No, I really appreciate you bringing this to us. And I agree with Ben. I think it's such an interesting opportunity to show our kids our world, what we do. Mine is a little bit younger than yours are, but I've taken every opportunity we can to involve her in the work that we're doing. I think it makes them more understanding about when we've got to work or go to work or take call.

And it lets them explore a little bit in real time things that may or may turn out to not be interesting to them. And so I think that's really neat. My question about involving your kids in your work is, how was that taken by the rest of the group? Your other collaborators, people in your division, what did that look like?

Dinushan Kaluarachchi (21:18.762) Yeah, no, they really, really liked it. I mean, they knew him from when he was a young child. So it was great to work with the group. And also he presented this at a local meeting, so a lot of people came to talk to him and ask him questions. The same thing in a regional meeting, as well as at

at the PAS as well. So he also had a great experience talking to different people coming from different backgrounds and asking questions and things like that. And people who talked to him, not knowing that he's my child, kind of come back to me and said, no, he did a great job explaining, and he really knew what he was talking about. So

Ben Courchia, MD (22:17.117) Dinushan, thank you so much for coming on Journal Club and for talking to us about your different papers and for this collaboration that you did with your son. It was definitely very interesting. And you were mentioning that you are working on upcoming larger studies and trials. Do you want to tease that a little bit before we close the show?

Dinushan Kaluarachchi (22:38.06) Sure, yeah, definitely. We are working on two trials. One I actually presented at the Delphi meeting a couple of years ago. It's almost about to start. We have gotten the IRB approval and the FDA IND. What we are doing is late surfactant mixed with budesonide for prevention of chronic lung disease. So that study will start this fall. So we are very excited about that.

And the other study that we are planning, we actually completed a pilot trial in Jordan on this. We call it TACO and SALSA, which is a prophylactic SALSA trial. So we have conducted the initial pilot, a single center study in Jordan. We are analyzing the data right now. We are in the stages of planning the study to do it in the US again as a pilot study. So the basic idea is, we use

an LMA, a supraglottic airway device. We have smaller devices now. In babies born between 26 to 31 weeks, we will use that to resuscitate instead of a face mask. And once the baby is stabilized, we'll give a prophylactic dose of surfactant through that supraglottic airway device. And the standard arm would be resuscitation with mask and selective surfactant,

the usual care. Yeah.

Ben Courchia, MD (24:07.901) Yeah, that's a topic that we've touched on the podcast multiple times in the past couple of months. So definitely something very interesting. Well, again, thank you so much for making the time, and best of luck with this upcoming work.

Dinushan Kaluarachchi (24:21.504) Yeah, thank you very much.

Ben Courchia, MD (24:23.114) Bye.