Veterinary Vertex
Veterinary Vertex is a weekly podcast that takes you behind the scenes of the clinical and research discoveries published in the Journal of the American Veterinary Medical Association (JAVMA) and the American Journal of Veterinary Research (AJVR). Tune in to learn about cutting-edge veterinary research and gain in-depth insights you won’t find anywhere else. Come away with knowledge you can put to use in your own practice – along with a healthy dose of inspiration to remind you what you love about veterinary medicine.
Veterinary Vertex
Beyond Warming Blankets: Rethinking Temperature Control in Feline Surgery
Hypothermia during anesthesia represents one of veterinary medicine's most common yet preventable complications. While warming methods abound, which ones actually work? Dr. Rachel Kreisler and veterinary students Mahtab Khanezarrian and John Boules join us to challenge conventional wisdom and share evidence-based solutions.
Their groundbreaking research reveals something surprising: those cotton toddler socks commonly used in clinics provide absolutely no benefit for maintaining feline body temperature during procedures. Instead, their carefully designed "kitten mittens" made from down blanket material demonstrated remarkable effectiveness, keeping cats up to 1.2°F warmer with passive insulation alone. When low-voltage heating elements were added, temperature preservation improved even further.
The science behind this breakthrough centers on redistribution hypothermia - the averaging of warmer core blood with cooler peripheral blood during the critical first 45 minutes after induction. By focusing protection efforts on the extremities rather than just the trunk, veterinarians can make a meaningful difference in patient outcomes. The research team shares practical insights about preparation timing, environmental temperature management, and pre-warming considerations that can be implemented immediately in practice.
Looking ahead, Dr. Kreisler discusses promising new materials that may offer superior insulation while addressing the practical challenges of sanitation and reusability in clinical settings. Whether you're working in a standard veterinary practice or a specialized setting like MRI where warming options are limited, this episode delivers immediately applicable knowledge to enhance patient care. Listen now to transform your approach to feline temperature management during anesthesia, and discover why evidence-based medicine matters for even the most routine procedures.
JAVMA article: https://doi.org/10.2460/javma.25.02.0095
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Speaker 2:You're listening to Veterinary Vertex, a podcast of the AVMA Journals episode. We chat about how insulating the extremities of cats with highly insulating materials during anesthesia reduces core temperature decline, with additional benefit from active warming, with our guests Rachel Kreisler, matab Kanazarin and John Boulis.
Speaker 3:Welcome listeners. I'm Editor-in-Chief Lisa Fortier, and I'm joined by Associate Editor Sarah Wright. Today we have Rachel, john and Matav joining us. Hey you guys, thanks so much for being here with us today. We know a couple of you are vet students and very busy time of the year, so really appreciate your time today.
Speaker 2:Thank you for having us.
Speaker 4:Yeah, thank you for having us, it's not a problem.
Speaker 2:All right, let's dive right in. So, rachel, you're a repeat guest on the podcast and we're so excited to be chatting with you today about cats. So your Jabna article discusses how covering the extremities of cats undergoing anesthesia with highly insulating materials slows the core temperature. Can you share with our listeners the background on this article?
Speaker 5:Sure Thanks. So I was. This goes back actually a couple of years. I was curious about the insulation of extremities because I'd noticed that a lot of clinics use cotton toddler socks during anesthesia to support the maintenance of the core body temperature. And this really surprised me, because during the first 45 minutes or so following induction of anesthesia, the greatest contributor to the drop we observe in core body temperature is actually just the averaging of the warmer blood from the core with the cooler blood from the extremities. So the fancy term for this is the redistribution hypothermia, and for the most part heat's not being lost to the environment. It's just again this sort of averaging of cooler and warmer blood as the arteriovenous shunts go offline because of the anesthesia. And so it seemed true, especially for our cats. They're furry, so they're probably not losing as much to the environment as compared to people. They've got fur, so there's less radiant loss and things like that.
Speaker 5:So a couple of years ago we ran a study to see if cotton toddler socks helped maintain core body temperature, and it turned out they didn't help at all, not even a little bit, not even a fraction of a degree.
Speaker 5:And in that same study we also looked to see if low voltage heating elements inside the cotton toddler socks would help, and they did, but it was only about half a degree Fahrenheit sort of at the end of the day, so not very impressive.
Speaker 5:So I guess for all that work we were like definitely there's no reason to use cotton toddler socks. But when we were writing up our manuscript we were of course making sure we looked at other studies and there was one that used bubble wrap on the extremities of cats and also covered their thorax, and they did seem to find a difference. But their cats didn't look like our cats in terms of you know, our patients are prepped at an average of 11 minutes and these guys took about an hour and they actually were hitting the surgical table between 94 and 97 degrees Fahrenheit, and that's just not similar to us at all. So we decided to run this study and see if using better insulating materials might make a difference. So our first step was to run an in vitro study to determine the best insulating materials, and I'll let Matab tell us a little bit more about that.
Speaker 6:Yeah, so we warmed up four 500 milliliter lactated ringer fluid bags in the food warmer and we actually used these like barbecue probes to measure the temperature on the inside to just for our whole, because it was very nice, it had a online like portal or sent all of the data so we're able to measure every minute to see how everything was insulating. And we used different insulating materials like bubble wrap, wool, socks, and we use down blankets and we did these trials with nine different variations of materials and thicknesses three times and we found that the two layers of the down blanket uh performed the best and that's what we used to make the kitten mittens and we uh the mittens were used to like passively insulate the extremities of cats and some of them. We sewed in active warmers and they're low voltage heating elements and those had like wires that we set up and sometimes they had batteries, sometimes we had to find an outlet, and so we compared the passive without the heating elements and the active with the heating element to just our control group that got truncal one.
Speaker 4:Yeah, and just to add on to that a little bit, the heated mittens worked pretty well, with the lowest recorded temperature being 1.9 degrees Fahrenheit warmer than the controls, so we did see a little difference there.
Speaker 6:Yeah, and the passive mittens worked pretty well too. They had ended up being up to 1.2 degrees Fahrenheit warmer than our control group and, like I said, they didn't have the wires, so they were just a little easier to use, especially if you weren't next to a power source or forgot your batteries somewhere.
Speaker 4:There were also a few other things that played an important role as well that we tried to look at, the first being the temperature that the cat started at, so initial temperature of the core at the time of induction. Also the temperature of the environment, whether it be the OR or the prep area before heading into surgery and, not surprisingly enough, the actual duration of anesthesia how long each surgery took, how long each patient was receiving drugs and under anesthesia. One other factor was weight that we looked into, but surprisingly enough for our sample size, weight was not that significant.
Speaker 2:One thing I really loved about your manuscript was the figure where I think you were showing like the techniques you just described, and when we were promoting this article on social media too, it was really cool to see the veterinary community come together and share their experience and say, hey, now there's evidence behind this and we can implement this into our practice. So really great clinical relevance, I think, too, with this article.
Speaker 5:We had a group doing MRIs contact us because they have very limited ability to warm their patients during the procedure, and so that was really exciting to see that we could maybe provide some good evidence for something that would help their patients. Of course, I'd go with the passive insulation, but yeah, that's more than a degree warmer for the lowest recorded temperature. Yeah, that's, you know, more than a degree warmer for the lowest recorded temperature is our precip. You come up with a cutoff that you say this is clinically meaningful before you run your study, and one degree was what we had decided on, just as sort of a consensus of what we thought would be OK. That's different. No-transcript, very cool.
Speaker 2:And what are some of the important?
Speaker 5:take-home messages from this article.
Speaker 5:In addition, to sort of again, if you're in a situation where you have some limited heating options, this could be a good method to incorporate. But I would say it also focuses on some things like minimizing the time it takes in prep. The first 45 minutes is when the core temperature decreases the quickest and once that heat's lost, so to speak, even if it's still in the body, it's not going to kind of get sucked back into the core. It will eventually be lost to the environment. It's much harder to get it back than it is to try to keep it in the cat to start. So really being thoughtful about how your process is and trying to make sure that you're minimizing that downtime before they can make it into surgery, if you're going to insulate the extremities, make sure you use well-insulating materials. So the cotton toddler socks throw them away or give them to toddlers they're not helpful for this purpose and I would say keep your prep, or and recovery areas as warm as you can stand.
Speaker 5:Obviously you have to be concerned about human health and safety, but I've definitely been in ORs that I'm very uncomfortable, uncomfortably cold, and so anytime you have a greater differential between the ambient air and your patients, you are going to lose heat more quickly. And then, finally, cats should be as warm as possible before inducing anesthesia. So if you run a trap-neuter-return program, maybe in the Northeast, and your cats are arriving in the morning, maybe a little bit on the chillier side, if you can, you know, give your patients time to warm up. There's some evidence that some sort of like warming of course, you know, within physiologic appropriate range may be helpful. That's a little bit mixed, but definitely we don't want to send them into anesthesia if they're already cold, if we have a chance to warm them up first.
Speaker 3:Yeah, really, really great information you guys. Rachel, this is obviously, as Sarah said earlier, a repeat performance on the dog side of things. What sparked your interest in this insulation side of anesthesia?
Speaker 5:Yeah. So in addition to sort of the myth-busting approach to inspiration for the cotton toddler socks, I was really intrigued by a study done in the 1990s that looked at active warming of the extremities of dogs and that was found to be more beneficial than truncal warming. Bit deeper, there were some studies that supported warming the extremities of humans undergoing anesthesia, so I thought that it was really worth checking it out because, again, we know that hypothermia does lead to poorer outcomes for our patients, so anything we can do to help support their core body temperatures should be helpful.
Speaker 3:Yeah, super important for all of our clinicians. You all have described tons of really interesting findings from the article, but always when we do these things, something surprises us. Was there something in this article that you're like huh, I didn't expect to find that.
Speaker 5:I didn't think the passive insulation was going to work. I didn't think the passive insulation was going to work. I really did not expect to see it perform almost as well as our active warming. I guess in some ways because again there's some thought that it's less than 20% of that first decrease in temperature is again lost to the environment, and that's looking at people, which we can. We have a lot more radiant surface and and things like that, and so I I thought maybe we would see 0.2, 0.5 degrees and, um, this is why you run, really you do research, because, uh, what you guess is not always, uh, what the case.
Speaker 2:So that surprised me, rachel. We're going to start calling you our MythBuster author, because last time you were here you're talking about vaccine viral puncture.
Speaker 5:right, yeah, it is the uniting theme of a lot of my research. Yes, I can tell.
Speaker 2:So, rachel, what are the next steps for research in insulation during anesthesia?
Speaker 5:Ah. So I actually have found a high-tech material that I think may have superior performance for, even as compared to what we've looked at before. So it'd also be more convenient and easier to sanitize or perhaps even autoclave than the down. The down was a little challenging to work with. We actually used Matab's sewing machine to sew these sort of mittens, and you know there's down everywhere, there's still down in my car, and so I think that, and you know sort of and using it repeatedly over time, I think would be challenging to keep it clean. So I'm kind of excited to take it to the next step running some of these fluid bag trials actually this week and also making sure it doesn't melt in the autoclave.
Speaker 2:Very smart and AI is a really hot topic. We asked you about this last time you were on the podcast. We're going to ask you again do you see a role for AI in this particular area of research?
Speaker 5:Yeah, so maybe it wouldn't be my first thought, but I know that when we were, john Mottob and I were all sitting around and we pulled up, we looked at all this literature when we're trying to decide what would we test in vitro and see right, because even though the fluid bag tests were pretty easy to run, they still took time and materials and things like that. And so we kind of did our best guess, guided by this literature search. But I think that you know we've seen in some areas like drug discovery, or that you know there's be a wide range of suggestions and suggestions you might not have thought of, sort of it comes at, I don't want to say a different way of thinking, but you know in some ways a different way of thinking, and so I think definitely that could have broadened our horizons in terms of the materials that we considered.
Speaker 2:And for those of you just joining us, we're discussing how insulating the extremities of cats with highly insulating materials during anesthesia reduces core temperature decline, with additional benefit from active warming, with our guests Rachel John and Matab Matab and John as veterinary students.
Speaker 3:How did any of your training or previous work help you to prepare to write this article? We'll start with Matab and then go to John.
Speaker 6:So in undergrad I worked in a research lab for almost four semesters and it was completely different. I thought coming into this I was like, oh, I've done research, but it was a very pleasant surprise to be able to do research with live animals and, you know, really feel like, okay, I don't have to wait years for this research to be important, like right now. You know we have. I left the insulating materials in our surgery lab. I was like anyone that wants to use them, please feel free. You know we have the research to back it up now and I think just working as a tech you know, before veterinary school and being able to have a feline hands-on experience really helped me. So, yeah, outstanding.
Speaker 3:How about you, John?
Speaker 4:Yeah, lisa, thank you very much for that question. In my years of work prior to beginning veterinary school, I gained a lot of experience with surgery and working with anesthetized patients, so I developed a very good understanding of basic temperature trends in patients under anesthesia and I also developed the understanding of how important it is to use supplemental warming devices to try and prevent further heat loss that we can see.
Speaker 2:Yeah, super cool to see your previous clinical experiences inform this research, so we look forward to seeing what maybe you do in the future too. So this next set of questions is going to be very important for our listeners, rachel, what is one piece of information the veterinarian should know about insulating the extremities of cats during anesthesia?
Speaker 5:I would say that it can be helpful, but be sure to use a highly insulating material that's well-fitted.
Speaker 2:Very well said, and Matab and John, what's one thing clients should know about this topic.
Speaker 4:I think that one thing clients should know about this topic is that, when used correctly, these warming devices can only help their patients while under anesthesia.
Speaker 6:Yes, I think client education on hypothermia with cats is really important, and just knowing that it's just going to keep getting better as the research progresses with Dr.
Speaker 3:Kreisler. Fantastic, you have a good mentor. As we wind down, we like to ask a kind of a fun question. So, rachel, for you, what is the oldest or most interesting item on your desk or in your desk drawer? I?
Speaker 5:can say that actually I want to pick somebody else's desk because I was chatting with another veterinarian about a different research project and they had mentioned that their mentor had recently cleaned out their desk. They were retiring and they found a Parvo sample from seven years ago and, of course, very curious, they did find it was still viable. Obviously, probably a desk drawer is an ideal environment no UV light, climate, controlled but I just thought that that kind of rocked my world right, Because we think of it as maybe up to two years. But so I guess if you, if you've got any Parvo samples in your desk, be very careful with them.
Speaker 3:That's a little terrifying. Yeah For John. We'll ask if you could have a superpower, what would it be and why?
Speaker 4:If I were to have a superpower, my superpower would probably be super speed, like the flash or something like that. I think having super speed, I can get anywhere where I want very fast, and you can also fly technically run on water. There's a lot of science behind it and I think I'd be able to accomplish a lot with it.
Speaker 3:Yeah, some people say like teleport, so that they can get home to family or go to you know, relatives or fun concerts or whatever. So then we'll transition over to you, matab, with the word concert. What was the first concert you attended?
Speaker 6:The first concert I attended, I was actually six years old and it was my mom's favorite band and it was a Persian band. And it was a Persian band. And I remember falling asleep on stage next to the boom box because I was like this is just past my bedtime. I had a great time. I remember that concert actually pretty vividly for six years old.
Speaker 3:Wow, if you have trouble sleeping some night, maybe just put some loud, booming music on. Exactly.
Speaker 2:That's awesome. Well, thank you all for being here today and also for sharing your research, too, with Jabma. We appreciate it.
Speaker 6:Thank you for having us.
Speaker 2:And to our listeners. You can read Rachel John and Madtop's article on Jabma. I'm Sarah Wright with Lucid48. Be on the lookout for next week's episode and don't forget to leave us a rating and review on Apple Podcasts or whatever platform you listen to.
