OR Sustainability and end-tidal control | ANESTHESIOLOGY®2023

Top Med Talk.

Desiree Chappell: Well, hello and welcome back. We're here at Anesthesiology 2023, the annual meeting with the American Society of Anesthesiologists. I'm Desiree Chappell, host of Top Med Talk, and I'm joined by my co-hosts, Mike Grocott and Guy Ludbrook. Gentlemen, thank you so much for coming back and sitting down with us.

Guy Ludbrook: Always a pleasure.

Desiree Chappell: So Mike Grocott, co-editor in chief of Top Med Talk with me now.

Mike Grocott: As of this morning.

Desiree Chappell: As of this morning, Mike, how are things been going at the meeting this weekend?

Mike Grocott: We've had some really fascinating conversations today. Really looking forward to the conversation that's coming up. It's been really good. It's great to be back.

Desiree Chappell: Yeah. And guy, you're joining us. You're on sabbatical from Australia.

Guy Ludbrook: Yeah, I am indeed. It's just great to get out into the world again, see people face to face, interact again. It's just terrific. And what I've learned this morning alone has just been astonishing.

Desiree Chappell: Yeah. We always have great conversations at Top Med Talk and here at Anesthesiology. And we just want to say thank you to the ASA, the American Society of Anesthesiologists, for supporting us to be here. That means a lot. We couldn't do it without them, and we couldn't do without the generous support of all of our sponsors, GE HealthCare, Edwards Life Sciences, Medtronic, they have kept the show on the road. And without you, we couldn't keep Top Med Talk free and open to the world.

Desiree Chappell: We just had over 2 million downloads this past summer. I know. And we're listened to in over 100 countries. And this is a figure that I just get tired whenever I say it. Over 2000 podcasts we've had here on Top Med Talk. So lots and lots of good content you can find at topmedtalk.com. We've been here, here at the ASA meeting over the last couple of years and had some great conversations about sustainability in anesthesiology. And today we're going to have another one with David Hovord, who is from the University of Michigan. David, thank you so much for joining us.

David Hovord: Thank you.

Desiree Chappell: Yeah. So for our listeners who may not know you, can you tell us a little bit about yourself, where you're from and a little bit about your research interests?

Mike Grocott: Yeah, sure. So I did my anesthesia training in England, as you might be able to tell. And then about ten years ago, I did a year at the University of Michigan, and they invited me back permanently on their liver transplantation team. So I'm a member of the liver transplant team there, the liver anesthesia team, and I managed the equipment and supplies, and I took that job over about two months before the pandemic, which turned out was good or bad timing.

Desiree Chappell: You got very busy.

David Hovord:  So I kind of got busy, and it was a great opportunity to learn a lot, which I did. So in terms of my research now I'm really interested in sustainability, which kind of stems from all the equipment and the supplies that we use. And I'm the co-lead of the green anesthesia project, or green anesthesia initiative we call it or Gaia. Yeah, there's a clever link there.

Mike Grocott: We like that

Desiree Chappell: I know, I was just going to say, we like that a lot. I caught that.

David Hovord: I didn't think of that, that was the chair. He's cleverer than me. The majority of what I'm doing now is working to see how we can improve sustainability. First, in anesthesia, mainly anesthesia gasses is what we think about, but also more broadly in the OR.

Desiree Chappell: Yeah, absolutely. Let's just dive right in and talk about what are some of the issues with sustainability, because as a clinician myself in the OR just doing things every single day, I don't necessarily always think of that. And I've learned a lot in other conversations that we've had about this, about product waste, all the different disposables that we use in addition to the anesthetic gasses. So can we talk about the problem for team anesthesia when it comes to sustainability?

David Hovord: Yeah, I think the thing that comes first to mind are the gasses that we use.

Desiree Chappell: Yeah.

David Hovord: The patients. The gasses tend to get vented straight into the atmosphere. So I think there's two main issues that come from that. One are the CO2 equivalents and the impact on the global warming cascade that we're seeing. And the second is the ozone layer and the effect that these gasses have on the ozone layer. So I think you can separate those two things. There are four main gasses that we use every day. Well, we may not use every day, but we have.

Desiree Chappell: Some of us may use more than others.

David Hovord: And the big one is nitrous oxide. It does two things. It hangs around in the atmosphere for more than 100 years.

Desiree Chappell: Oh, wow.

David Hovord: It's a couple of hundred times worse than CO2 per unit in terms of global warming effect, or CO2 equivalents. And it breaks down the ozone layer while it hangs around. So it does a couple of bad things, and we use a lot of it. If your flows are at two liters a minute for the whole case, and if you're 50% nitrous. You're using a liter a minute.

Desiree Chappell: Yeah.

David Hovord: That's quite a bit compared to the volatile agents that we use. Probably a few ccs, depending how well you're doing.

Desiree Chappell: Yeah.

David Hovord: So the nitrous oxide story is interesting because you don't really have to use it. You can just use twice as much of another agent. And so when we started to look at what we were using, we realized that we bought about ten times more than we were giving to patients. And then when we kind of asked around and looked around a bit, it seems that the pipeline that we use in hospitals in general is the cause of that. So you can lower your nitrous use if you like, but if you've got a massive tank full of nitrous attached to a pipeline that's working its way through the hospital, it's probably leaking about 90% of what you're using.

Desiree Chappell: Our eyebrows are all raised on that.

Mike Grocott: I've never heard that before. That's quite astonishing.

David Hovord: So I think I've got to pay credit to Dr. Cheesebourgh here in Oregon, and he's the one that started a ton of work on this stuff, figuring out where all the leaks are. And essentially, if you just carry on doing what you're doing in nitrous, but attach a cylinder to the back and use a cylinder, you're going to cut your usage by 90%.

Desiree Chappell: No kidding. So instead of piping it through the system, just keeping it in there. Wow. And that's where we feel like most of this is coming from, because has there not been a movement? I know in my general practice, over even the last ten years, we've pretty much stopped using nitrous. Most of providers I know don't use it anymore.

David Hovord: Yeah. And it's important to stop using, I think, just so you can go to the tank on the back. If you're still using it all day, every day, it's very hard to keep switching that tank up, and you're just not going to be able to do that logistically. So when we started at U of M, the first thing we targeted was nitrous. And we're like, okay, what we've got to do is get the usage down to the point where we can just move away from this pipeline. So we shut the pipeline down. So the first thing we did, we're building a new hospital opening in 2025. We took the pipeline out of that hospital, so there was no nitrous pipeline in there. And then a few months ago, we shut off the pipeline in our cardiovascular center. And then today they're closing it down in the main hospital, which was a great day for me.

Desiree Chappell: Oh, yeah, sure. Congrats. That's great. So nitrous is an issue. We feel like we can stop using it if we kind of get to this other, broader issue of actually storing it and things like that. Anesthetic gasses are a problem as well. And I know some are worse than others, but we have desflurane, sevoflurane on our carts now. So it's really up. The decision is ours as providers. Right. With what to use.

Mike Grocott: Yeah, I think that's absolutely it. People often pose the question, hey, look, what's the point in doing anything when people are flying everywhere or we have polluting cars or coal powered stations? But we have a choice we can make every day for the patient. There isn't a great deal of difference about what we use. And so we can choose to use agents that are less damaging to the environment. And in short, that's sevoflurane.

Desiree Chappell: Okay. One of the questions I've always had, is there a way to better control, I guess, the amount of gas that we're giving and how we give it? High-flow versus low-flow and things like that?

Mike Grocott: Yeah, I think there's two points to this, really. There's the peri induction phase where you're preoxygenating the patient, and the temptation is to crank the machine up to 15 liters so the patient gets all the oxygen and that feels good. But really, they don't need more than eight. So if you start at eight, that's great. And then you're using half the amount. And then during the maintenance phase, you could use low flows. Now, I started anesthesia in London in 2005, and we've been talking about low flow anesthesia for a while, almost 20 years now.

Mike Grocott: I started about ten years earlier. They were already talking about it. Don't ask Guy.

Guy Ludbrook: A couple more years to that.

Desiree Chappell: We're talking about low-flows.

David Hovord: We've been talking about low flows for a long time. Yeah, I can show you grass from the U of M, where we say, hey, how about low-flows? And the flow graphs just do this. And people, the reason why is because there's lack of, I think, perceived benefit to the patient. You lose less heat and you lose less humidity. But that's not selling argument to balance against the risks, which are the risk of hypoxemia and the risk of inadequate levels of whatever anesthetic gas you're trying to. And we always say in an experienced hands now, it depends where you practice. If you're practicing in the UK. Well, as attending physician there, you'll be in the or with your patient all day, and then you can probably monitor very closely and you've got the ability to do that. It's kind of hard work, though, and sometimes you just might not feel like it. So it's just temptation just to turn it up a little bit and just relax a bit more. Or maybe your case is super intense. Maybe you're doing a liver transplant or, I don't know, AAA or whatever it is that's challenging for you, and it's the first thing to go. It should be really.

Desiree Chappell: Yeah. If you're really focusing. But that being said, a lot of the conversations we have had is how can we use technology to help us do our jobs better and improve the quality of care, improve patient safety?

Desiree Chappell: So there are some solutions now available that help us maybe manage that a little bit better.

David Hovord: Yeah. This is something I used in England just before I left. So I think we're talking about end-tidal control control, and that's only available in the US from GE HealthCare on their Aisys, CS2 machine. And what it essentially is is an autopilot system that delivers a precise level of end-tidal oxygen and end-tidal agent, whichever agent you're using. And it will do that at the minimal flow. Now, at the U of M, we set that at a default at 500 ccs a minute.

Desiree Chappell: Okay.

David Hovord: That's an order of magnitude lower than anyone is doing it on their own.

Desiree Chappell: Yeah, for sure.

David Hovord: It's just not happening. It's possible to do that, but you have to focus solely on that, and that's not what we encourage our residents to do when we're training them. That's not really what we want anyone to do. I see this very much as a patient safety tool that allows low-flow anesthesia. I don't see it as being about the money. I see it as an important environmental tool, but I really see its main benefit in patient safety. You can't deliver a hypoxemic gas mixture. It will deliver the end-tidal sevoflurante or whatever gas it is you're using that you set it to. So it's just going to achieve that, it'll achieve that quickly and stably, and it frees up anesthesiologists and the residents to think about other things.

Mike Grocott: Yeah, I'm interested. If it can't achieve the goals with the given flow, what's the automatic response? Or is it an alarm response?

David Hovord: It depends what the reason why it can't do it. So there's an alarm that kicks in if there's a leak or whatever. Say, if you change the level of anesthetic and it realizes it needs to increase the anti-sevo, it will kick up the flows and then bring them down again. And then bring them down when it's ready.

Guy Ludbrook:  And, look, as an environmental risk of being an environmental vandal, I have to say, and what I have learned is the thing about nitrous oxide, because I do use it in appropriate cases, but I need to go back and get some cylinders out. So that's a great learning from today. But we have that system available, and it has turned me from a moderate to high-flow user to an automatic low-flow. It is a set and forget. And we've already talked this morning about some aspects of how technology can avoid distraction. If you're sitting there absolutely having to play with your flows and titrate your vaporizer, you're really not doing some other things. So, look, I agree on a patient safety perspective. It stops me being distracted. But these important environmental issues, I think, speaks to that incredibly well. So I've become an incredible convert. You just have to work on the nitrous oxide a bit. I think it's a game changer, personally.

Desiree Chappell: Yeah. And being in the OR, and there are a lot of other things going on, and there are plenty of times, especially whenever we're going through generations of ventilators and anesthesia machines, where once it was the knobs turning everything up. And you want your flows up because their saturation is down a little bit, or you need to deepen the gas or lower the gas just a little bit. So you turn up your flows, and then ten minutes later, like, oh, my God, I'm running my flows at five liters or something like that. I think this is great. I mean, it is a set and forget and keeps you kind of on track. So you don't kind of go way over or way under. And so that, to me, is very appealing. When our patients are more complex, there's a lot more going on in the OR. We have a lot more distraction with the robots in the rooms and things like that. So having technology like this, I think, is actually the future. And that really will contribute to helping with all the other things. Burnout and all those things that really are tough every day.

Guy Ludbrook: We've done the withdrawal trial, so in my main hospital, we have that, and that's great. And then I sometimes go out to other hospitals. They don't have them.

Desiree Chappell:  What is that?

Guy Ludbrook: So the automated control. So we have that in many of the hospitals I work in. Then I go to one that doesn't, and then I sit back and look at my flows and kind of wince it, even though I might be more conscious than once was. You just don't do it because you forget or whatever, or you get distracted, whatever. So there's a noticeable change in the way I approach it and I see others do. So, yeah, I think it's incredibly important for all the reasons that you've told us.

Desiree Chappell: Go ahead.

David Hovord: I was going to say we have the same thing. We've rolled it out a lot. Like some. All of them. And I was working with a resident the other day, and we put patient to sleep and they turn around to click it on machine. They're like, oh, man, where is it? And that, I think, tells you what you need to know about it. It's been very powerful. People really appreciate having it.

Desiree Chappell: Yeah, absolutely. And I mean, as an environmentist myself, and those things are really important to me. I'm also try to be a good financial steward. And so we know if we're reducing the cost of what it is that we're using, it's a win-win, right? We have to look at all the ways that everybody wins in this situation.

David Hovord: Yeah, I mean, it is a win-win, and it can display the cost per hour of the agent. We actually haven't done that because I didn't want this to be about "it saves money". Self-evidently does. Yeah. But really, for our green anesthesia initiative project, our Gaia project, if you like, we moved from nitrous and isoflurane to siva, and that's a lot more expensive. And then as we roll at end-tidal control, our Siva use drops. And so we think we can probably get back to almost cost neutral with 90-95% reductions in CO2 emissions.

Guy Ludbrook: Yeah, we have money on ours, and it's quite a lot of money. Actually, once you look at it, it's quite a lot of money. So, yeah, we've been sort of, either we forgot to turn it off or whatever, but it is sobering, that part as well.

Desiree Chappell: Yeah.

Mike Grocott: David, let me ask you, because we're all having this conversation, and it makes complete sense, because we've done high-flow and low-flow, and we've sat there and done the thinking. 10-20 years in, how are we going to teach folk? And this is an argument against it, but I'm just saying, how are we going to teach folk why it's important and how it all works if they just press a button and it just happens.

David Hovord: Yeah, this is a really good question that I spent a bit of time thinking about. And the way that I learned about low-flow anesthesia was. I still remember it. I was in Woolwich General Hospital, I turned the flows down and then the Sevo kept dropping.

Desiree Chappell: Yeah.

David Hovord:  I said, the ODB, there's something wrong with this machine. Looking at me like, you've been doing this for three months, probably you. And he was right. And that was how I figured it out, because no one really taught me. And I think you can still teach it, you can understand it. There's lots of tools available online to teach it and understand it, but it's very difficult to execute it in everyday practice. I think we found that and proven that over 20-25 years in the same way as when people brought in ultrasound for central lines. People know and will know how to do landmark, and we now think that they shouldn't know how to do landmark. Now the residents are all using ultrasound for arterial line placement. I finally had to learn because they can get it first time every time. It took me a few years to adopt that. Adopt and agree that it was actually better, and it is better, but it just takes a little bit of time sometimes to come to that realization. I still think that that palpation is important, but if you've got an awake patient, how can you justify doing that?

Mike Grocott: Absolutely.

David Hovord: And so if you've got an end-tidal control on your machine, how could you justify turning the flows down low to show to someone how it works? When you've got an automated system that does it more safely.

David Hovord: You just wonder how much more of what we do will be automated.

Desiree Chappell: Yeah.

Mike Grocott: Very interesting.

Desiree Chappell: But it's not technology to take over our jobs. I don't think that's ever possible. Someone has to have human eyes on these things. But again, if we can do it better and it's better for our patients, for patient safety, why not instead of why?

Guy Ludbrook: And it's all about this AI conversation we've been having. It is AI that's filtering the information, doing stuff for us, and allowing us to do much more complex tasks which, let's face it, with our population, the way they're heading in age and comorbidities, we're desperately needed in that space. So, yeah, it's a little piece of AI that's not scary and really kind of works.

Desiree Chappell: And I know not everybody loves the analogy with the airline industry for anesthesia, but again, I'm sure pilots had a tough time whenever autopilot was taking over.

Mike Grocott: but fly by wire, all that tech,

Desiree Chappell: Absolutely, 100%. That's where we are. So, David, fantastic conversation. Thank you so much for enlightening us. Again, I think we saw our eyebrows raise a couple of times here.

Mike Grocott: And great to have the accent on the show.

Desiree Chappell: I was just going to say, oh, my goodness, once again, I'm outnumbered here on Top Med Talk. But, David, if we want to find out more information about some of the things we talked about today, like Gaia and some of the other things you're involved with, where's the best place to find that.

David Hovord: I'm more than happy for people to reach out directly. I've had people do that after a few things that I've done. So people can either email

Desiree Chappell: We'll put all that staff on the show notes. We will put all of this information in our notes, you will still have that at your fingertips. Again David, thank you so much. Thank you for listening to Top Med Talk, you know you can find all of our content at topmedtalk.com. This particular podcast will be also up on Youtube as well as everything we have done here at the ASA and we will putting that out through our podcatcher later in the month so please do check that out. We are out in X, LinkedIn, Facebook, you can find a lot of information there as well. Again, thank you for listening, thank you to our sponsors that make all this beautiful conversations happen. Cheers everybody.

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