#71 Cord Gas Essentials: What L&D Nurses Need to Know

Sarah Lavonne:
Hi, I’m Sarah Lavonne and I’m so glad you’re here. Here at Bundle Birth, we believe that your life has the potential to make a deep, meaningful impact on the world around you. You as a nurse have the ability to add value to every person and patient you touch. We want to inspire you with the resources, education, and stories to support you to live your absolute best life, both in and outside of work. But don’t expect perfection over here. We’re just here to have some conversations about anything, birth, work, and life, trying to add some happy to your hour as we all grow together. By nurses, for nurses, this is Happy Hour with Bundle Birth Nurses.
I feel like I’m a pretty smart person. I feel like I love to learn and I try really hard. I was that student in nursing school that had to work very hard and had to read and write it, and then I would teach it to my friends and then I would sort of get it, and then my best nursing school friend would party all weekend and show up to the class and get an A and I’d get a B+ and very annoying, but I can keep up. But there’s one area of nursing/OB that I am a dumb dumb. I have tried so many times, I’ve talked to NICU doctors, I’ve sat and read the books. I have taken the classes. I don’t know if there’s any one specific class on this, but this is not something I have not put effort towards. And to date, I am still, and I feel like there’s no hope for me, unable to grasp the concept of cord gases.
And I think we all sometimes have to look at our reference sheets, or if you were to pull up a CBC, I’m not going to be able to tell you what anything other than an H and H should be probably, or platelets. But it’s like to look at the numbers. But I have such a hard time. I think it’s because the patho for me is really hard to grasp and there’s so many different systems involved and whatnot. And so we have Heidi here, one of our educators who is an expert at cord gases, this is your thing, I think.

Heidi:
I really do like cord gases.

Sarah Lavonne:
Yeah. And she’s like, oh, we can talk about it. I’ll teach you. So we’re going to learn all about cord gases today. And I hope that I’m not alone in the dodo feeling of my head of like, I feel like it’s a little more complicated than some other things. And if you get it, then you get it. And this will be a great review. But otherwise, we’re going to break down cord gases and try to learn them together and see if there’s hope for my future in cord gas learning and understanding.

Heidi:
There’s always hope. And you don’t give yourself enough credit. You’re so smart. We all have things that it’s just our brain has to work harder at, and this was something that my brain had to work harder at first initially, and I don’t like not being able to understand things.

Sarah Lavonne:
Same.

Heidi:
And I hate being left out. And so I hated hearing people to be like, oh yeah, the gas is this and that. And I’m like, I don’t want to be left out. How do I speak the language that I’m the same as you where I’m like, okay, I need to start reading this. I want to understand it. And babies were something that I started doing a few years into my career. I didn’t do it right out the gate. I was asked to, I was tried to pretty much voluntold into it, which I feel like that happens. And I kept saying, no, no, no. And finally then I was like, okay, I’ll do it. I’m ready to do the next thing and challenge myself. And so anyways, that’s how that kind of came about.

Sarah Lavonne:
Tell me about, what’s your spiel? So I’m a new nurse and you’re precepting me. How cute. Wouldn’t that be adorable?

Heidi:
Oh, that’d be so fun. We’d have so much fun.

Sarah Lavonne:
That’d be so fun. I feel like I would need a precepting. Coming back to the bedside now I’m like, I’d need somebody like you holding my hand. And the charting. Oh my God.

Heidi:
Oh yeah. The charting changes so much.

Sarah Lavonne:
It changes so much. And I pay attention when I’m at births, but I’m like, oh, thank God. And I just out of sight out of mind. And that’s one of the blessings of being a birth coach is I take notes, but they’re my own and then I don’t have to chart like y’all do.

Heidi:
Yeah. I know. The charting is out of control and all the stuff we have to scan now and it’s crazy. That’s a whole other deal.

Sarah Lavonne:
Yeah.

Heidi:
So cord gases, they kind of started becoming a big thing in the later part of the 20th century to really give us a good idea of what’s happening in the fetus at time of delivery. And so the whole purpose of it is to guide care of the newborn, particularly in a baby that we’re concerned about it having acidemia. So when we collect cord gases, it really gives us another piece of the puzzle to tell us whether or not the baby should qualify for cooling. Because in the event of HIE, which is hypoxic ischemic encephalopathy, oh my goodness, I can’t talk, that is the only treatment that we have for that. And one of the worst things for HIE is not recognizing that a baby needs to be cooled and thinking that they’re, quote unquote, fine after we’ve done a great job, resuscitating them, and then 24 hours later they start seizing because we’ve missed that window for them.

Sarah Lavonne:
Well, and that for us, we’re not going to see necessarily, right? It’s easy for us to be like, oh, they’re skin to skin, it’s fine. They needed a little resuscitation. But otherwise, typically we’re not going to even know.

Heidi:
Right. Yeah. And so that’s where being able to interpret those gases really comes into play, especially if you work in facilities that are low risk and you don’t have a NICU team that is there looking at it, that you’re the nurse that is looking at it. And so we’ll talk through how to do that. But with the development of cord gases, there’s been tons of studies, what do the research say about it with collecting proper gases and getting that Sarnat exam, which is this neuro exam that’s done on the baby. They’ve had an increase where they’re meeting criteria for cooling by 94%. 94% of the time they’re recognizing it based off of getting good gases.

Sarah Lavonne:
Oh, wow.

Heidi:
And so that’s a huge piece. That’s super, super important. So when we collect gases, we’re looking at the arterial because in the artery that’s going to be the end point in the fetus that’s giving us the truest picture of what is going on in the fetus. So that’s the blood that is going away from the fetus, going back to the placenta to become reoxygenated. Whereas the vein is what is being delivered to the baby.

Sarah Lavonne:
So when we get the artery, it’s directly from the baby, it’s as if you’re taking a sample from the baby.

Heidi:
Yeah. And so we collect the venous because it’s just another way that we can prove that we have arterial. So everyone’s like, why do we get the vein? We don’t really necessarily care about what the vein is other than just to prove that we have two different samples.

Sarah Lavonne:
What if the vein is bad?

Heidi:
What if the vein is bad?

Sarah Lavonne:
Yeah.

Heidi:
Then the artery is going to be bad because everything works on a gradient. So you would expect there’s naturally going to be higher oxygen levels at the side of the pregnant person so that it is more readily available for the fetus. So if it’s low on the pregnant person’s side, it’s going to be low on the baby side, most likely.

Sarah Lavonne:
Low or lower?

Heidi:
Lower. They’re always going to be lower. Yeah.

Sarah Lavonne:
Okay. And if they’re not?

Heidi:
And it they’re not, then you probably have both vein. So when we’re looking, we’re going to collect those two samples. And why this happens, why we get veins sometimes when we think we’re getting arterial is because the vein is big and squishy, it’s so much easier to obtain then the arterial. So we’re going to want to try to get the arterial first and then subsequently collect from the vein.

Sarah Lavonne:
Can you poke both arteries?

Heidi:
Yeah, you can poke from both.

Sarah Lavonne:
Okay. It’s not just one or the other.

Heidi:
No. Yeah, you can poke from both, but you want to try to limit how much you’re poking around because then you’re going to just have this big bloody mess.

Sarah Lavonne:
I think that’s a good point to make because I don’t know that I… The vein is so easy, you’re like, oh, duh. But really focusing on getting the arterial, I had not made that connection until you started talking about this. And so it’s getting the arterial is the point, that the vein kind of doesn’t matter. The arterial really does matter. And so being really, really particular with your technique to, I’m going to get this arterial.

Heidi:
When you’re comparing the values, if you think about how everything works on a gradient and things are going to be higher in the pregnant person than they are in the baby, that’s going to kind of give you a clue too. So in the artery, your pH should be 0.02 to 0.08 less than venous. So that’s your first thing that you can look at in comparison to be like, do I actually have two different samples here? And then the other thing you can look at just purely for another comparison is the partial oxygen level. Again, that’s going to be lower in the fetus, and that’s going to be between 32 and 34 in the artery. So if it’s higher than that, you know that you have venous. So those are going to be the two things-

Sarah Lavonne:
32 and 34 in the PO2. In the artery.

Heidi:
In the artery, yes.

Sarah Lavonne:
And 0.02 to 0.08, higher, lower-

Heidi:
It’ll be higher on the venous side.

Sarah Lavonne:
Higher on the venous side, lower on the arterial side. So there needs to be a discrepancy between the pH of the venous and the arterial by 0.02 to 0.08. And if there isn’t, you likely have the same vessel.

Heidi:
Yeah. And so that’s really important to know. Because if you do that, then you can say like, hey, okay, we need to draw a subsequent sample because you may look at that and not, and if you don’t recognize that, then you’re thinking those numbers are normal and that’s going to kind of change the course for the kiddo.

Sarah Lavonne:
Right. And this is particularly because I think from talking to you and learning about your facility, you don’t have the same access that I have had. I’ve had level three NICUs everywhere I’ve been, and so I was never responsible for the results of these results. They’re there and I would look at them and I’d be like, oh, the pH, blah, blah, blah. Oh, bad. But in my head I’m like, oh, okay, how bad and what’s going on? And so we’re going to figure that out together because I can’t ever remember. But especially for those of you that are at those hospitals that don’t have direct NICU pedes care for the baby and you are the primary one, you need to be looking at these and potentially escalating if you’re seeing the results that we’re going to talk about that we don’t like.

Heidi:
Yeah. Okay. So let’s move into talking about the levels. So since we’re nurses and we go off of what A1 says, ACOG will say about 7.2 for pH, it needs to be higher than 7.2 for pH, but A1 says greater than 7.18. So when I’m evaluating cord gases, there are three numbers that I look at, which you’ll get several other numbers, but these three numbers that we’re going to talk about are the most important at being able to figure out what’s going on with the baby. So write these numbers down, we can even-

Sarah Lavonne:
We’ll make a post.

Heidi:
We’ll make a little post about it. Okay. So first thing you’re going to want to look at is what the pH is. So if your pH is greater than 7.18, you can kind of move on with your day like okay, we don’t need to look further, relying on the fact that you’ve compared and like, yep, I clearly have an arterial sample, not both venous. The next thing you’re going to look at is your CO2 level. So normal is below 60. And then the third thing you’re going to look at is your base deficit or your base excess. So it’s just going to depend on what your facility uses. Some use base deficit, some use base excess. So it’ll either be between negative 12 and 12. It needs to be within that range. If it’s outside of those ranges, then that’s abnormal.

Sarah Lavonne:
So negative 11 to positive 11, we’re good?

Heidi:
Mm-hmm.

Sarah Lavonne:
Kind of.

Heidi:
Yeah.

Sarah Lavonne:
Okay

Heidi:
For that third piece.
So there are a few different combinations of things that we can have going on. So one of the first things that we can see is respiratory acidosis. So this would be where they’re still in aerobic metabolism, meaning that they still have some level of oxygen available for exchange, that they’re able to have CO2 as a waste product. They just don’t have as much oxygen circulating to bond to that CO2. So their pH is going to drop because they’re acidic. So your pH is going to be lower than 7.18 and your PCO2 is going to be greater than 60.

Sarah Lavonne:
Because if we think about a normal breath, so I breathe in, there’s oxygen outside, I breathe in oxygen, I absorb that and it goes into my bloodstream, and then when I breathe out, I’m breathing out CO2. And mind you, in a baby, they’re not breathing in that same way. I think that’s partially also what gets my mind messed up. But if there’s oxygen coming in, then the CO2 goes out, but if there isn’t oxygen coming in, the CO2 can’t go out, therefore it accumulates, therefore it increases beyond 60.

Heidi:
Exactly. See, you got that.

Sarah Lavonne:
So we have excess CO2 therefore in a respiratory situation, but their respirations, quote unquote, is really the cord and the oxygen transfer between mom baby.

Heidi:
Yeah. Because at this point the cord is still being used, so their shunts are still functioning.

Sarah Lavonne:
And it’s like first line of treatment that we’re thinking, okay, so our options for when we look at our cord gases, it’s like totally normal, okay, brush to the side. There’s respiratory acidosis, metabolic acidosis and mixed.

Heidi:
Yes.

Sarah Lavonne:
And that’s what we’re looking for. But a respiratory is really the first one. It’s like we’re not in the tissues, we’re not going into other ways of metabolizing and trying to keep the baby alive. It’s like there’s an interruption.

Heidi:
Yeah.

Sarah Lavonne:
It’s basically what that means.?

Heidi:
Yeah, you were kind of talking about they’re still having oxygen available to them, but it’s just less than what they need. So it comes on pretty quickly. And that’s why once they’re delivered and we clamp that cord and then they’re not using that for gas exchange anymore, they have oxygen readily available to them in the air, their circulation goes from that right to left, to left to right then they’re able to do that own gas exchange, it’s going to self-correct pretty quickly. Or they may need a little bit of respiratory help. They might need a little bit of CPAP to kind of perk them up.
So your abnormal levels are going to be and the pH is going to be less than 7.18, and then your CO2 is going to be elevated. It’s going to be greater than 60, but your base deficit and your base excess are going to be normal because you aren’t having that anaerobic metabolism where the lactic acid comes into play because the base deficit and base excess are what buffer off the acid. Because everything works in a check and balance. So if one thing’s high, the other thing’s going to be low to try to maintain homeostasis.

Sarah Lavonne:
So the base excess base deficit normal, because once we start seeing some of that, that’s when we start to have other types of metabolism/energy being used to help baby survive.

Heidi:
Yeah.

Sarah Lavonne:
Is that it?

Heidi:
Yeah, they’re trying to maintain their cardiac output. Yeah.

Sarah Lavonne:
Okay, so we have decreased pH under 7.18 and CO2 elevated everything else normal is respiratory acidosis and in that case, we are not requiring cooling because it will self-correct once they breathe.

Heidi:
Yeah. They may need a little bit of help from us. They may need a little bit of CPAP, but usually it’s more like they’re breathing really fast or they just need a little bit of stimulation and then they’re good. So we’re not doing these huge resuscitations for these kiddos.

Sarah Lavonne:
Okay.

Heidi:
Yeah.

Sarah Lavonne:
Okay.

Heidi:
So kind of segueing on top of that, when we were talking about the base deficit base excess, when we move into metabolic acidosis, that’s where the metabolism changes. So this is where we don’t have oxygen available anymore for exchange.

Sarah Lavonne:
None.

Heidi:
Nope, it’s not there. So then you are not going to have that carbon dioxide as a waste product. You’re now going to have lactic acid as a waste product. And so this is where it becomes really dangerous for these kiddos because they’re now not only lacking oxygen in their blood, but they’re lacking it in their tissues. And so this is where it’s really, really crucial for them that we’re getting them delivered quick and recognizing that and they’re going to need more help at birth because they were lacking oxygen to their brain and this is a cooling thing is going to come into play.

Sarah Lavonne:
So in that case, I am thinking about clinically and what clinical scenarios we would see for something like this. So I would imagine a prolonged decel for whatever reason, that a quick cutoff, say there’s a knot in the cord and it gets pulled and there’s a complete cessation of blood flow to the baby, you’re going to see the heart rate drop and in that case very quickly move towards a metabolic acidemia, correct?

Heidi:
Yeah.

Sarah Lavonne:
In that case-

Heidi:
It depends how quickly they deliver to that point. Right? So if you recognize that and they’re delivered pretty quickly, if they were not depressed before that, you could just have a respiratory acidosis from that. So metabolic acidosis is they have had chronic obstruction of their oxygen pathway going on for days or hours. Yeah.

Sarah Lavonne:
But if there’s no oxygen, how are they still alive?

Heidi:
I don’t know. That’s the little bit of magic. That’s where they don’t have very good outcomes.

Sarah Lavonne:
So I’m thinking, okay, so when I hear metabolic acidemia, the phrase we say in fetal monitoring is a category three, you cannot rule out metabolic acidemia. Right? So they have their tacky, it’s horrible that their absent variability, the baseline’s 170, no decels, and no variability or obviously excels. So in that case, it moves to a cat three. We can’t rule out metabolic acidemia, but we’re drawing gases because there’s a high likely, what, 50 50? Isn’t that what you guys say?

Heidi:
Yeah, it’s 50 50 for whether or not the baby is going to come out needing help or not. Yeah, so we’re going to draw gases on that kiddo just as another piece because there is a chance that they come out appearing fine, but their gases are not good. And so then that just qualifies that they need more work up because we don’t want to miss the opportunity for them to be cooled if that is what they do need. So when we’re looking at levels for metabolic acidemia, again, our pH is going to be less than 7.18. Our PCO2 is going to be less than 60 or right around 60. It’s not going to be elevated because that’s not-

Sarah Lavonne:
They’re not using the respiratory.

Heidi:
They’re not using that anymore.

Sarah Lavonne:
Processes.

Heidi:
And then you’re going to see the change in the base deficit or the base excess.

Sarah Lavonne:
And that’s the by-product of lactic acid. And lactic acid happens when you’re in anaerobic metabolism.

Heidi:
So yeah, so the base deficit in base excess is what’s trying to buffer off the acid.

Sarah Lavonne:
I don’t know what you mean by buffer off.

Heidi:
So it’s trying to get rid of it.

Sarah Lavonne:
It’s grabbing the lactic acid. So they’re not rhabdo is what I think of with lactic acid. I have a horrible story with rhabdo. I went biking when I was in college and I got suckered into a 42-mile bike ride without any training and I was fine until I wasn’t. And then I ended up with a mild case of rhabdo as a result. Don’t do that. It hurts. These poor little babies with tons of lactic acid. So when I think of metabolic acidosis, acidemia, regardless, I’m thinking oxygen to start, but then it’s your metabolism, metabolic. So it’s into what your source of energy is to supply the tissues with glucose, something, whether it’s glucose or glycogen or whatever you call it, sugar, to fuel the body’s survival, correct?

Heidi:
Yeah. So there’s still glucose at play, but instead of having the carbon dioxide, then that’s where you’re going to have the lactic acid, which is just very damaging to the tissues. Think about how horrible your tissues felt after you were biking too much.

Sarah Lavonne:
Yeah, I literally couldn’t move. It was like I was hedged ahead, sharp stabbing pains in every ounce of my body. I’d lift a finger and it would send a shock wave through my body. It was awful. These poor babies.

Heidi:
Yes. So circling back to that with metabolic acidemia, then you’re going to have low pH, your PCO2 is going to be normal, because it’s not a respiratory component anymore. You’re now in this anaerobic cycle and your base deficit base excess is going to be outside of that negative 12 to 12.
Okay. And this is going to take longer to develop. It’s not they all of a sudden get like this. So it’s like they’ve had this disruption in their oxygen pathway going on for a while. So maybe they were having weights for a long time or they’ve had minimal variability or they’ve had a cat three for quite a while, that proper interventions were not done or were not done in a timely manner. So since it takes longer to develop, it’s going to take longer to resolve. So these kiddos are going to need resuscitation at time of birth.

Sarah Lavonne:
Yeah.

Heidi:
And this is where you just got to watch them really closely because even what I’ve seen with reviewing cases is, I kind of mentioned this before about their gases kind of getting missed and then they resuscitate them and they appear fine, they put them skin to skin and then 24 hours later they’re seizing. And what we worry about with that is with HIE, they’re having major areas in their brain that are without oxygen, and then we do such a great job with resuscitating them and then those areas are perfused. And so we’re sending now all this highly oxygenated blood to these tissues that are damaged that it actually can worsen their injury and give them these, what they call watershed injuries where it’s just kind of all across their brain.

Sarah Lavonne:
What?

Heidi:
It’s so important to be able to recognize this or recognize that things are abnormal and get them down the proper avenue of care. The next thing we have is mixed acidosis. And this, I know this is so confusing, but you kind of have two separate disease processes going on at once. So there’s a respiratory component to it, and then there’s also a metabolic component to it. So their pH is going to be less than 7.18. Their PCO2 is going to be elevated because they have that respiratory piece, but then they’re based-

Sarah Lavonne:
You mean the cord and the oxygen transfer from the parent is not necessarily compromised?

Heidi:
It may or may not be. It’s kind of like how two things can be true at the same time. So they can have this respiratory component going on, but then they also have this metabolic component going on, so they’re still going to have lactic acid present. So I was kind of asking some NICU nurses about this. Because I kind of had it in my mind for a while that mixed is worse and it’s sort of like apples and oranges. It’s just going to really depend on whatever clinically is happening with them. These kiddos are going to be born depressed too. They’re going to need resuscitation.

Sarah Lavonne:
Well, and I think that’s a good point that looking at any value, a fetal monitoring tracing or cord gases or labs or the affect of the patient is never just a singular thing that we have to be looking beyond just the cord gases of what’s going on, what happened going into it, what was the tracing, what’s the maternal history, was there other potential complications along the way, et cetera, et cetera. Rather than just looking at them individually. In my mind, a mixed acidosis, if they have the respiratory component, wouldn’t that be somewhat compensatory because it means there is that oxygen transfer?

Heidi:
Yes and no, but also then they… I don’t know, see that’s why I kind of always thought just in my own head, they’re almost more sick because they have a respiratory and this other-

Sarah Lavonne:
It’s like their body’s working so hard.

Heidi:
The body’s just working so hard. But it’s really just going to depend on the context. But again, they’re going to need help. So when we’re kind deciding who to draw gases on, AGOG does not recommend drawing gases on everybody. It’s going to be your population that has a low five-minute Apgar. Are they IUGR? Do we have a cat two or cat three tracing? Was there a complicated delivery? Did we have a shoulder? Whatever it may be. Did we need a vacuum? There’s meconium stained fluid. They also recommend it with multiple gestations. So there’s a whole list of things that they have for criteria for who should get gases because it’s not just like, we’re just going to do it on everybody because that’s really not, doesn’t make sense to do that.

Sarah Lavonne:
Well, and if you’re at a birth, we sometimes forget how stressful births can be for providers as well. But I can see… In fact, this last birth I was at a few days ago, they drew gases and we had a category two tracing that was just very strange. It was one of the more weird tracings I’ve seen recently. And it was also like I have the privilege of being there from literally the start. So you talk about going back and in your [inaudible 00:29:41] monitoring classes, I’ve heard a lot of you have to go back and you have to look at the history of the tracing. What was it? What happened along the way? Is this normal? What’s been their baseline? What’s been going on? And I was able to watch literally since they put her on the monitor until this birth. And so we had mostly category one the whole time, but every once in a while we would have these ridiculous prolonged decels.
Like I’m telling you, Heidi, we had, take a deep breath, a 14 minute decel, and they did not move her to the operating room. And you can imagine being the nurse in that room where you have no control clinically, and I’m looking at it like… I unhooked everything. The epidural little remote thing was tied around the bed railing, which if anybody has followed me at all, they know that that’s one of my biggest pet peeves in the world. Do not tie knots in your stuff. If you have to go, you can’t go as quickly. Regardless, so I’m unhooking things. The remote is off to the side. At one point in the decel, I turned the IV pump so it was facing them because the pit’s still on. There’s nothing I can do hardly. But we had a full-blown 14 minute decel to the forties and it resolved.
And of course afterwards it’s like tachycardia minimal variability for a while recovering. So of course that kept happening throughout, but mostly category one, this baby came out, didn’t require really any resuscitation, but they drew court gases. Okay. So when we’re approaching those scenarios, one, if you’ve been a part of these cases and you’ve been watching a tracing that’s been category two and the doctor doesn’t suggest it, it is appropriate to even just mention, do you want gases, doctor? Because especially I’m hearing from all of this, I’m like, that information can be extremely helpful and potentially missed in the grand scheme of things, especially if baby comes out crying. And this baby came out crying and I’m still trying to get ahold of those gases from the patient’s chart.

Heidi:
Oh, I thought you were going to surprise me and be like-

Sarah Lavonne:
I know. I’m sorry.

Heidi:
We’re going to [inaudible 00:31:57] a live interpretation together.

Sarah Lavonne:
No, I’ve been asking her because you know how they get access to their notes and their chart and their lab volleys and stuff. So I’ve been asking her, but it’s been low on their totem pole of stuff. So if I get them, we’ll turn it into a case study on a tracing Tuesdays or on Instagram or something.

Heidi:
Oh, I can’t wait. That’ll be fun.

Sarah Lavonne:
But obviously no cooling required. Baby went home, there was no concern. And this was at a place with the NICU. And so I assume they were fine, but especially if you’re in a facility that where they’re not fine, or sorry that you don’t have a NICU, making that suggestion is just one more potential-

Heidi:
It’s just one [inaudible 00:32:35] piece that we have. Totally. Which I think really reassuring. So yeah, the next time you have a patient where cord gases are drawn, everybody should be looking at them and trying to understand them. It’s such an important thing and I think it’s just so interesting.

Sarah Lavonne:
You think so. I’m going to sit there with my cheat sheet, like, okay.

Heidi:
There’s no shame in having a cheat sheet.

Sarah Lavonne:
For sure.

Heidi:
If you have to have it there, I had that for a long time. I had a little cheat sheet that I would look at. But I think the easiest thing for me was just taking those, just those three numbers. Because there’s several other numbers that come back with it, that’s overwhelming to me. But when you break it down and it’s really just those three values, so the pH, PCO2, and the base deficit or base excess, just looking at those, I’m like, that seems so doable.

Sarah Lavonne:
And for a mixed, I’m going to have, everything’s going to be all out of whack.

Heidi:
Yeah.

Sarah Lavonne:
So elevated PCO2, base excess deficit outside of 12, negative 12. And then we know it’s mixed, but it’s not necessarily worse or better, it’s just different as we say. Not better, not worse, just different.

Heidi:
Yeah. But why we want to look at those is because for cooling, if they do meet criteria for cooling, the recommendation is that cooling is started within six hours of birth.

Sarah Lavonne:
What is meeting criteria?

Heidi:
So there’s a few different things that they’re going to look at and there’s a whole list of things, but they have to be greater than 36 weeks, within six hours of birth. Their pH has to be less than seven or a base deficit greater than 16. And then for some reason, if you weren’t able to obtain gases, then they’re going to look, was there an acute perinatal event? Did they have an Apgar of five or less at 10 minutes or did they have assisted ventilation that they needed for at least 10 minutes after birth? And then that Sarnat exam that’s done, they have to score by meeting at least three out of the six criteria. So there’s several things that go into it, but the gases are a really important piece of that.

Sarah Lavonne:
What if they can’t get a sample?

Heidi:
That’s what I was talking about, that if they can’t get a sample, then they’re going to look at was there an acute event that happened at time of birth, a stressful event, was there a cord prolapse? Was there a shoulder? Did they have to have a vacuum? Things that like, oh, okay, this obviously stress the baby out more. And then also looking at their Apgar scores, and then did we have to help them with ventilation for at least 10 minutes after birth? And then they’ll still do that Sarnat exam and score them on it. So they’ll look at those other things.

Sarah Lavonne:
Okay. And they’ll just skip it.

Heidi:
Yeah. But the gases are helpful piece if you’re able to get that.

Sarah Lavonne:
Yeah.

Heidi:
Because that six hours can go by quick. And they still can cool them after six hours, but from what I’ve heard from people that are far more experts and experienced than I am and do this all the time and do cooling, because we obviously don’t have cooling at my facility, they said, yeah, we can cool them after six hours, but the research isn’t that great on it. It’s really kind of like, meh. We’ll still do it to say that we did.

Sarah Lavonne:
Yeah, yeah.

Heidi:
The best outcomes come when you’re hitting by that six hour mark.

Sarah Lavonne:
This brings me back to mentorship because in our mentorship program, we call it O baby, but it’s like neonatal stuff for birth, and it’s particularly specific for labor and delivery, less LDRP, but we brought in a NICU nurse to talk about HIE and some of the more common things that you see, and her explanation of HIE in there is so, so helpful. That was important for me even in my learning across the years, because especially if you’re not in the NICU, we just don’t know. And it goes back to the beginning of we a lot of times don’t see this stuff, and we don’t actually know that we had a birth that the baby seized and went to NICU and we missed the window. Oh, that’s so devastating. None of us want that.

Heidi:
Yeah, no, no, we don’t want that at all. So there are resources out there that can help us in mentorship and yeah, I think it’s so interesting learning about all of that.

Sarah Lavonne:
So what’s our role that you would say, I’m a new nurse, you’re precepting me, what’s my role related to cord gases? What am I responsible for?

Heidi:
So you potentially will be the one collecting them. So if we’re going to talk about collection, you’re going to need between 0.1 and 0.3 mils for each sample, and you’ll just have to kind of check with your lab to see how much they require. Really the keys to collection are you’re going to want to have slow steady collection, not a bunch of poke, poke, poking around trying to get little bits out. And you want to make sure that you don’t have any air bubbles in there when you’re collecting it. So if you get an air bubble in there, you can just kind of push it out. But if you leave an air bubble in there, it can actually falsify your results and it can increase your pH and decrease your PCO2.

Sarah Lavonne:
Oh yeah. So you think it’s fine, but actually your little air bubble missed the window.

Heidi:
Yeah.

Sarah Lavonne:
That’s stressful.

Heidi:
Yeah. Once you know that, I feel like that’s so easily fixed. Yeah.

Sarah Lavonne:
But also as nurses, aren’t we obsessed with the air bubbles? I was drawing up into a syringe the other day for my plants. I give them vitamins. And you give them three mils of vitamins. And Dakota, my nephew, was helping me and there was all this air and I was like, “Hold on, hold on. We must get out the air bubbles.” So also keep that in mind. He was like, “Why does it matter?” It doesn’t actually at all matter, you’re putting it in water. But as a nurse, we care about those air bubbles.

Heidi:
Yeah, yeah, we do. And so as far as collection, time-wise, they are stable at room temperature for 30 minutes. So beyond that, you’d want them on ice and you really definitely want to collect them around that 30 minute mark. But when the cord’s doubly clamped, whatever value you draw from there will be stable for 60 minutes. Beyond that, you’re going to start having your pH fall like 0.2. So it’s important to try to-

Sarah Lavonne:
Even on ice?

Heidi:
[inaudible 00:40:04] them.

Sarah Lavonne:
That’s why we rush them.

Heidi:
That’s why we rush them.

Sarah Lavonne:
I’m like, who’s taking my gases?

Heidi:
It’s important to know that piece of why that matters.

Sarah Lavonne:
Okay, well, and also they’re probably looking at the time of birth and the time of drawing, and then the time of that to weigh in, get them there, send them off.

Heidi:
Get them done.

Sarah Lavonne:
And then is there anything else I’m responsible for?

Heidi:
Then depending on what your facility is, if you have a NICU or not, then you’re going to be watching for those to come back and just ensuring that they’ve been looked at, are they normal? Are they not normal? And in the event that they’re not normal, then communicating that with a provider to ensure that the baby is heading down the right trajectory. So that’s it. That seems so doable.

Sarah Lavonne:
I still want my cheat sheet, but I think as of right now, I don’t know about tomorrow, but as of right now, I feel like I could tell you… In fact, do you want to quiz me? Let me do a recap. Okay, ready?

Heidi:
Okay. Do you want to do, I’ll give you a little quiz. Your pH is 7.01.

Sarah Lavonne:
Okay. It’s low.

Heidi:
Okay.

Sarah Lavonne:
So we’re not discarding. It’s not discarding.

Heidi:
It’s not discarding. Right. Okay. Your PCO2 is 45.

Sarah Lavonne:
So that’s normal/low.

Heidi:
Okay.

Sarah Lavonne:
So it’s not a respiratory.

Heidi:
Okay. And then your base deficit or base excess is 18.

Sarah Lavonne:
Ooh, we need to cool this kid.

Heidi:
Yeah, they need some more care. So what type of-

Sarah Lavonne:
Wow, that did actually make it very easy.

Heidi:
What type of acidosis would this be?

Sarah Lavonne:
Metabolic.

Heidi:
Yeah.

Sarah Lavonne:
Okay. It’s not that hard. I don’t know why. Okay, but you’ll have to quiz me tomorrow and the next day and the next day because-

Heidi:
I’ll send you some texts and I’ll quiz you. That’s the piece too. See, I think you put such a burden on yourself that you not only want to be able to do this, but you want to understand everything down to a microcellular level.

Sarah Lavonne:
I do.

Heidi:
Which is amazing.

Sarah Lavonne:
Yes, I do.

Heidi:
Which is amazing, but in the clinical context of things, that’s not what you’re going to be responsible for. My little preceptee.

Sarah Lavonne:
I know. Can you imagine me as an actual preceptee, I’d be a nightmare. I was a nightmare actually. They found me less annoying. My counterpart was on another level, so she very much balanced me out and made me look good as far as my questions go, plus I’m very much, especially back then, but I’m working on being a people pleaser, and so it was like, okay, I’ll figure it out on my own and I don’t like to ask for help. So there was a lot going on when I was being precepted, but currently I do. I’m like, but why the lactic acid and how does that relate to the oxygen and what do you mean oxygen cessation and in what scenario? This and that. And I think I can get there, but for now, baseline, what do we need to know? We need to know how to draw them. We need to know how to do it in the most accurate way possible, and we need to be able to compare. That would be one you need to send me is the comparison. 0.02 to 0.08 discrepancy in pH is what we’re looking for.

Heidi:
Yeah.

Sarah Lavonne:
Between the artery and the vein, and we’re looking at the arterial because that’s the one that’s going out from the baby, therefore drawing the level from the baby to give us a baby representation of what’s going on in baby versus vein going to baby, that hasn’t even hit the kid yet. So that’s not at all accurate for what’s going on inside of them.

Heidi:
So hopefully this has been helpful to others too, or sparked a little interest to do a deep dive.

Sarah Lavonne:
Well, I appreciate your expertise, Heidi, and I also appreciate just you being on the team as one of our educators. If you don’t know, Heidi is one of our instructors for RNC OB prep course prepping you for your exam. So if you are interested in the RNC, taking the exam, you really should do a class. That’s what everybody does, and it will help you pass. We have a pass or your money back guarantee going with ours, and it’s such a fun day getting to learn. Just even if you’re not doing RNC, for me, it was this amazing overview of the heavy hitters, one slide on things we barely see as a great reminder to keep us up to date and keep us leveling up our practice. As we know you around here at Bundle Birth Nurses are the type that take their learning really seriously.
You’re lifelong learners. If you haven’t listened to that episode, we’ll link it down below because it is one of our values around here, and Heidi is just such an incredible instructor and an incredible representation of a lifelong learner. She read… I am going to link the Gabe’s book because I just pulled it out again.

Heidi:
I feel like I should start being sponsored.

Sarah Lavonne:
You should. Absolutely you should. You should ask them about an affiliate program because this textbook, y’all, is the fattest most intimidating looking textbook ever. And then she was like, no, it’s the best. She read it twice for the RNC OB prep, but that’s the type of person, that’s where I know I found my kindred spirit because that’s absolutely something I have and would do. I have not read this one, but I’ve read many of the others and in preparation for any of our classes that I teach, that’s the type of obsession that ensues, and so you know you’re getting the best of the best when it comes to our classes that we offer here.
So you can learn from Heidi in the RNC class. There’s classes online. We’ll link that down below. If you want more from us, we have so many things going on. We’d love to have you in a class. Based on your needs, if you are struggling with, I need to learn about this, or I feel not confident in this, just send us an email at nurses@bundlebirth.com and we’d love to help figure out where you fit. At bare minimum, thank you for listening to the podcast, and then you can always find us on Instagram.

Heidi:
Thanks so much for spending your time with us during this episode of Happy Hour with Bundle Birth Nurses. If you liked what you heard, it helps both of us if you subscribe, rate, leave a raving review and share this episode with a friend. If you want more from us, head on over to bundlebirthnurses.com or follow us on Instagram.

Sarah Lavonne:
Now it’s your turn to go and find a cord gas to look at, and the next time that it’s indicated, maybe suggest it to your provider. And when they come back, start comparing the two arteries and vein and see what you got. Let’s all become better at our cord gas interpretation, myself included. We’ll see you next time.