Dec. 9, 2024

🔓 Anesthesia-Associated Hyperkalemia. (Or, That Thing That Greyhounds Do When You Anesthetise Them) With Dr Stacey Jones

🔓 Anesthesia-Associated Hyperkalemia. (Or, That Thing That Greyhounds Do When You Anesthetise Them) With Dr Stacey Jones
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Get the show notes for this episode, plus a very neat treatment guide for hyperkalaemia, ⁠here.⁠

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You may have heard about a condition where greyhounds can become dangerously hyperkalaemic under anaesthesia, but did you know that this isn’t something that happens exclusively in greyhounds? And do you know what the risk factors are for this happening, what you can do to try and prevent it, or how to preempt it? If the answer to any of these is no, and you ever anaesthetise non-human species, then this is one of those “will probably save a patient’s life one day” episodes.

 

Our guest is Dr Stacey Jones, who was involved in publishing the first ⁠paper on anaesthesia-associated hyperkalaemia⁠ in greyhounds that brought this condition to the veterinary world’s attention. She joins the podcast to share what she learnt while conducting the research for this paper, as well as to provide an update on the work that has been done since that first publication. This update fleshes out our understanding of the condition, focusing on what you need to know about it in practice.

 

Episode Topics and Timestamps

04:06 Symptoms and Detection

07:27 The Greyhound Project: A Case Study

19:15 Hyperkalemia Beyond Greyhounds

22:05 Practical Takeaways

27:53 Conclusion and Additional Resources

 

They did a retrospective study of Ekgs in patients that had known hyperkalemia in humans and the take home message was that they were missing about 50% of severe cases of hyperkalemia with EKG.I'm Hubert Einstra and you're listening to The Vet Vault where our promise is to help you find the strategies, tips and tools, whether that's non clinical or clinical, like this episode, to make you a better, happier vet.
And one of the most reliable ways to instantly ruin your happiness on any given day in practice is to have a healthy patient to rest on you under anesthesia.In this episode, we'll reduce that risk for you by clarifying anesthesia associated hyperkalemia.You know that thing you've heard about in greyhounds where they randomly go hyperkalemic and their hearts try and stop on you when you're anesthetizing them?
Well, as you'll hear in this episode, it's actually not just the greyhound thing.And we're going to make it a bit less random for you.This is one of those will probably save a patient's life one day episodes.Now there are three reasons why I chose to unlock this specific episode for you from a subscriber clinical podcast and share it with the whole world.
Number one, as I said at the start, having a patient try to die on you during anesthesia sucks, and I love sharing ways that make your job as a vet suck less, and I think this is one of them #2 I find it inspirational that Doctor Stacey Jones, our guest for this episode, who was part.
Of the team who published The Big.Paper on anesthesia associated hyperkalemia and greyhounds that first brought this thing to the vet world's attention.It's not a specialist.Or a full time researcher.And she doesn't even work in an academic institute.She's simply a diligent and curious vet who noticed something and decided to figure out why it was happening.
So I wanted to put that out there.She's just like you.So that thing that's bothering you at work, follow your curiosity for all of our sakes.And then the third, the reason is that our first, I was a greyhound, so I have a massive greyhound bias.So anything I can get out there to make more greyhounds?
A survivor anesthesia I'd lift to ripe old happy silly.Long nose counter surfing age is a win for me.OK, let's get to the episode.Keep listening to learn what we know about this condition, what the risk factors are for this happening other than being a greyhound, and what you can do to try and prevent it and monitor for it.
We also have a Part 2 episode in our subscriber clinical podcast feed, which you can find at vvn.supercast.com.That's VVN for Vet Vault Network.Dot supercast.com.About how to treat it if it does happen to one of your patients or if you just want the show notes for that episode with the treatment, which has a lovely little mnemonic from Stacey that will help you remember how to treat any dangerous hyperkalemia.
Go to swiy.co/hyper K, that's SWI y.co/hyper KK with a capital or click on the link in the show description wherever you're listening to get those notes as well as the notes for this episode that you're listening to right now.
OK Doctor Stacey Jones and anesthesia associated hyperkalemia or how to avoid ruining your day with an anesthesia related catastrophe.Stacey, welcome to the virtual podcast.
Thank you so, so much for joining us.Thank you so much for having me.I'm so honored.I'm really excited.To talk about this, because I came across this topic, I had no idea that this was a thing.And then I saw a few discussions on the veterinary social media pages where people asking questions about it and somebody saying, well, thank goodness I saw this post because this happened to me in surgery.
And my patient would have definitely died if I didn't know about this syndrome, the syndrome of potassium and greyhounds and anesthetics, that combination and the things that can go wrong.So I'd love to introduce that concept to people who haven't heard of it, first of all, because again, I feel like it is that sort of thing that if you don't know about it and it happens, you're going to lose a patient.
But then also dig into the whys and the what do we do about it if that sounds like a good plan.That sounds great.Thank you so much.So what does it look like?Hyperkalemia.So what are we going to start seeing and is it ECG primarily where you start seeing stuff?
Well, obviously what you can see eventually is just a patient that's heart stops beating but before we.Get to that.Point What do we see?I think we all remember in veterinary school learning what seems to be implied that as hyperkalemia marches up and gets higher and higher, there can be a risk for EKG changes.
And it was somehow implied that you know after about 7 or 7 1/2, no equivalents per liter that the patient would be at risk for a cardiac event.And some of the first things that you might see would be tall tinted T waves or write into QRS complex eventually kind of leading to a loss of P waves or an AB block.
And you know, in really severe cases a sine wave or even just a rest.But I wanna insert a little take home point here that it's becoming more clear that ECG may be not as sensitive as we thought it was, and that sometimes severe hyperkalemia can occur without any ECG.
Any ECG changes and I'm realizing that I'm trans.I'm going back and forth between ECG and EKG.What would be the best one for your listeners?I don't know.I heard you say EKG and I thought, oh, did I say the wrong thing?Let's use it interchangeably so everybody gets it.
So Stacy, what you said there before about that you can start getting to a dangerous level of hyperkalemia before you start seeing ECG.Does that mean that if we screening like let's say we're checking an ECG in a patient that is potentially hyperkalemic, you can't relax just because you don't see any ECG changes or EKG changes, whichever you you prefer to have a continent you're on.
Basically you can have a nice normal trace and then suddenly going to sign rhythm or or just an arrest.Is that accurate that I understand that correctly I.Think it's possible?You know, as I, as I was preparing for this podcast and I was reviewing some of the literature that's come out since I left the Greyhound Project that we're going to talk about soon.
As an example, I was listening to the Human podcast when I was preparing for our meeting today.And one of the questions on the podcast was could the first symptom of hyperkelenia actually be cardiac arrest?And you know, the nephrologist was talking about that and quoted some some studies that had been performed.
And one of the ones that kind of stuck with me was that they did a retrospective study of Ekgs in patients that had known hyperkalemia in humans.And the take home message was that they were missing about 50% of severe cases of hyperkalemia with EKG.
And that was pretty shocking to me.And my perception of this phenomenon is definitely altered.Like knowing that now, I probably would go back and do things a lot differently as a younger version of myself.And we can talk about that a little bit later.
So the greyhound projects, I'll just give you some background.I was a General practitioner and our practice served a lot of greyhound families.We had a very large greyhound population and of course greyhounds have a lot of dental disease.
And so dental care was a very common thing that we were providing.And in 2013, there were three greyhounds straight in a row that had unexplained hyperkidemia under anesthesia and it kind of triggered a pattern for me.
So for me, these three straight in a row really kind of made the pattern click.And so, you know, it searched through the literature, could not find any of these reports checked in with some mentors of mine and anesthesia, no one had really heard of it.
So I reached out to the Ohio State University's Greyhound Wellness program and I'm so lucky to get Doctor Christine Kellogg on the line and she confirmed that she their their program had seen this phenomenon where Greyhound spell of hyperkinia under general anesthesia to such an extent that they were monitoring potassium every 30 minutes after the first hour in all their greyhound patients.
I mean, the greyhound community really has a fear of anesthesia.And I think that's because of some historical unexplained deaths and even young healthy greyhounds.And this to me was, I'm wondering in my mind back in 2013, like, was this maybe why I?
Remember even as a student being taught be wary of greyhounds and they they talked about stuff like the lack of distribution of, I said ISO, we forget which start with thiapentone and those sort of drugs that didn't distribute to the fat as fast.
So that was one thing that I was aware of.But beyond that, whenever I knocked out my own greyhound, I was nervous.Way nervous.More nervous than I am for my other dogs now that are not greyhounds because of this weird unexplained fear of stuff goes wrong with greyhounds and anesthetic.Yeah, and I, I think the greyhound community definitely mirrors that.
I do remember, I think it is thiopental that was a contributing factor.I never have used that in my career.I think it was kind of going out of service as I was coming into veterinary medicine.But, you know, some other things that greyhounds are kind of known for that might contribute to challenges with anesthesia would be they tend to be very fearful in the veterinary setting, and so they can tremble and shake and become hypothermic.
You know, there was some case reports a long time ago about do greyhounds actually develop malignant hyperthermia, which is a genetic condition that's triggered by some anesthetic components.And I think that the finding was that it did not seem like they were predisposed to movement hypothermia, instead just hospital associated hypothermia from being so anxious in the clinical setting.
So one thing on my mind in 2013 was how do we get this information out to the veterinary community so that we might be able to decrease the fearfulness surrounding anesthesia, especially if hyperkalemia wasn't contributing cause.
And so I wrote a letter to the caller Greyhound community at that time just letting people know about Doctor Kellogg's recommendations.And then I invited our community to keep follow the recommendations to measure the potassium every 30 minutes after the first hour.
And if they wanted to share any case information, I was keeping the database both for patients that were going under anesthesia at our clinic and then also kind of community.So together with the mentors, we worked over the next four years or so to monitor potassium under anesthesia and greyhounds.
And what we found was this pretty common story where there would be progressive or sometimes rapid increases in potassium that occurred the longer anesthesia went on.So I pulled a few examples out of the database so that like for these are some patients that went under anesthesia for dental care that were healthy patients that didn't have any other underlying contributing factors.
And the pre anesthetic potassium for the first patient was 4 point O.And then at an hour it's 4.7 and 1 1/2 hours 5.8.And at two hours 6.5 and the 2 1/2 hours 7.4 with no EKG changes.
We turned off the gas and even the fluid bolus 30 minutes later down to six and then 90 minutes later down to 4.5 S You know what we found is this pattern of mostly subclinical progressive hyperkalemia that seemed to increase over time and we did have several events with patients with EPG changes and those patients the very first thing that we kind of saw was decreased heart rate and blood pressure and it was unresponsive to atropine.
Just a quick.Interruption to tell you about another way that the Vet Vault can support you in practice, then we'll get straight back to Doctor Stacey.So.Here's a problem that I had.I'm learning so much with the clinical podcasts.But then every now and again I'd get a case that would throw a few curveballs at me and I'd struggle to practically apply the stuff that I'm learning in that specific case.
And here's my solution.Through making the podcast, I'd built up a network of very smart specialists.So I'd send them the occasional sneaky text message with a photo or some blood results or just a conundrum.Like there's this case.What do you think?Priceless, right?
Well, not priceless actually, because I've gathered some of these smart people in an online space where you can do exactly the same for about 15 bucks a month.Our specialist support space will give you access.To some extra brainpower.For your challenging cases and you get to ask as many questions as you want with your membership, we have a link for you in the show description or e-mail us at Info at Leave at vault.com to organize A-Team subscription.
OK, back to Doctor Stacey.So I want to come to do we understand why this is happening?But I think just underlining again that it's, if you listen to those blood results, it's it's sort of sneaks up slowly and then it's they're quite big jumps.
So what would you see clinically, let's say somebody's doing an anesthetic on a Greyhound and you're not monitoring.What will you see clinically in that patient if this is happening to your patient?So I mentioned that we had part of the database was community members that basically sent in case reports from their own hospitals.
And what we found was that there was some pretty severe hyperkulemonia going on like multiple cases where was over 8 and there was some sort of sudden event, decrease in heart rate, decrease in blood pressure, cardiac arrhythmia or even near arrest that required major interventions in order to reverse those patients.
We had some veterinarians even as far as California write in and sadly they had some fatal events that they documented.So when we look at our the database from just our clinic, we identified this phenomenon under lots of different conditions.
So I think importantly it occurred in in young healthy greyhounds with no other problems and even in the absence of A2 adenergic agonist.So like in the patients that we monitored over those four years, we documented 95 anaesthetic events in greyhounds during that period of time between and we didn't use A2 adenergic agonists in those guys and they were not hyperthermic.
And we could identify that this phenomenon happened in greyhounds with numerous different opioids, different types of fluids, LRS, Normar.We even tried, you know, sodium chloride without any potassium.We tried stimulating their own endogenous insulin with 2 1/2 percent dextrous insulin.
LRS It occurred on propofol, alfaxolone with isoflorine, and some of the other clinics that documented that it was even occurring with sedal fluorine.So, you know, it seems like there wasn't one specific thing that was the cause, but what we did note is that duration was definitely a factor.
So in 2018 Doctor Mama and I wrote an abstract that we presented at the ABA conference in Bonita and what we we described the prevalence of hyperkalemia in greyhounds during this period of time.
So of the 95 anaesthetic events that we documented during that period, 36 of those patients developed hyperkulemia, which we've defined as potassium greater than 5.6.So that's about 40%.
So 38%, about 40% of the anesthetic events in greyhounds in that four year period, those patients developed hyperkulemia.And of the patients that developed hyperkulemia, about 80% of those patients were having it developed after the two hour mark.
So 29 of 36 developed it after two hours and seven patients out of 36 developed it at 1.5 hours or less.So one factor that came really clear was duration of anesthesia.
So we did experiment with trying some low dose insulin and dextrous that was successful and after we started that we didn't have any patients that developed any sort of concerning hyperkuleania because we were able to actually keep it controlled at that after that point in time.
Can I just ask a clarifying question on your study?If you said this, that was 95 anesthetic events, does that mean just 95 greyhounds who went under GA for whatever?When you say event, you don't mean something that went wrong.It's just I knocked out a greyhound and now we're monitoring potassium.
Yeah, it wasn't 95 cases of hyperkalemia.It was 95 times where a greyhound went under anesthesia in our.Practice and 36 of them had hyperkalemia.That's that's a big percentage, right?That's a.Little bit scary.Yeah, it is.
And I'm just going to, I'm going to share this right now because it is kind of interesting.So we defined hyperkalemia as potassium greater than 5.6, but the Greyhound reference range where potassium is actually lower than that.
So then some documentation that greyhounds tend to, most greyhound patients tend to have potassiums between 3.5 and 4.4.So I'm just putting this out there that we use the standard dog range, but for greyhounds.
This actually if we had utilized the greyhound reference range, the numbers might actually be even higher.So just putting that in as a little gem right there.So you guys looked at greyhounds, but in the intervening time between when the study came out and now, is it definitely greyhounds or mainly greyhounds or only greyhounds or is this a a thing in other of our patients potentially?
Yeah.So when we were monitoring greyhound patients during that period of time, we actually saw one non greyhound dog in two domestic short haired cats that developed hypokalemia.And then when we went to the ABA conference and we were in Nana, we got a chance to talk to people from all over the world.
And you know, certainly many anesthetists had seen it at some point in other animals.And at that time we knew that it was occurring in large non domestic cats like tigers and lions as examples.
And they primarily thought at that time it was associated with the A2 hydrogenic agonist use because they were finding that if they partially reversed those patients or fully reversed those patients that had mitigated that.So that was interesting.
And then we at the ABA conference got to talk to Polly Taylor's group in the UK and they had documented 20 non greyhound dogs that had gone under anesthesia and developed.Hyperkelania for unknown reasons, one of them that it rested and they did find that acidemia was a common factor, but the biggest risk factor that they found was duration.
And so I kind of left off in about 2019-2020, you know, Doctor Mama and Doctor Kudo and Doctor Brock and I wrote a paper about recurrent hyperkelania in greyhounds that happened in individual patients who had hyperkalemia on the 1st anesthetic event, developed hyperkalemia on subsequent anesthetic events.
And so since then a lot of other to your question, a lot of other animals have been demonstrated to or reported to have this phenomenon occurring.So there were numerous reports and numerous species.
So some greyhounds in the UK.So one of the questions was, you know, was this a familial thing to greyhounds in the United States or just in my area?But it has been documented elsewhere in the world.So I don't think that's the case.And then it's been documented in non greyhound dogs and individual case reports and case series kids.
It's actually been a world study, but newly identified path.So ruminants, captive wolves, a horse that's a short hair cat, Bengal cat that had repeatable hyperkalemia and subsequent anesthetic events, and then a ton of more large cats, non domestic fluids.
But I think what's happening is we're starting to identify this phenomenon in other breeds of dogs and other species as well.So Stacey, to try and make this practical for your practicing veterinarian, does it still look like it is more prevalent in greyhounds?
Because when you mention those numbers from your study, that's, that's quite a lot of greyhounds, a lot of patients.So a, does this mean that be very aware of this when you are doing specifically longer procedures in greyhounds, but be keep it in mind for any lung anesthetic in any species.
If you suddenly see a drop in heart rate or weird stuff happening on your ECG or anything, check potassium.Is that a reasonable take away would you say?I do think that greyhounds appear to be over represented in the number of hyperkalemic events and I can only gauge that just by the fact that all of us anesthetize, especially stolen practitioners, you know, dogs and cats all the time and it's very rare for us to see something like that.
But interestingly, one of the papers that was referenced in a lot of the new case reports that were coming out was a paper that looked at acid base and electrolyte balance in crystalloid solutions and dogs that are under bling elective surgery for orthopedic issues.
And they're basically trying to look at hyperchloramic metabolic acidosis as an outcome.But what was really interesting was that fifteen of those 57 dogs in their study had hyperkalemia, 4 of the patients were above 6 point O and two of them had EPG changes.
So even though I don't know of any studies that kind of compared greyhounds to non greyhounds proactively looking forward in time, looking at potassium levels every 30 minutes over the course of the procedure, I do think that we might be missing a lot of subclinical hyperkemia even in other species or other animals.
Does that answer your?Question.It does.I'm just again trying to make it like this in terms of things we should worry about or preempt or monitor for or or maybe act on beforehand.Can we conveniently ignore it?And if it suddenly becomes clinical, then you do something about it or, or does it mean that any procedure in any animal longer than an hour and a half or two hours, you should occasionally check for potassium?
Because again, we want to be mindful of not over servicing.And they're not going to chase going on a wild goose chase for something that's going to happen in one in a million patients.Now we're doing repeat bloods on every single lung anesthetic.And I don't expect you to have the answer.I suppose I'm just mulling over the repercussions for me as a clinical vet who's going to be doing anesthetics.
What do I do with this information without becoming paranoid?Yeah, I think that's really important.And I, I'm not sure that, you know, the standard of care is going to change anytime soon.I think it's more of a proactively assessing risk factors in your own mind.
You know how we do that ASA risk factor assessment for all anaesthetic procedures.I mean, I think we can include potential for hyperkalemia in there somewhere.And I would absolutely say if it was a greyhound, no question, I would be monitoring their potassium levels proactively starting at starting in an hour.
And then I think about other risk factors.So like if you happen to be using an A2 adrenergic agonist, potentially you might check even in a non greyhound patient if it was going to be a longer duration of anesthesia.
I also just would consider, you know, any sort of contributing factors, you know, if the patient had diabetes or female disease or, you know, a cancerous process or they're going to be under procedure that was going to be causing, you know, tissue trauma or for a long period of time, or they were on drugs that were potentially could potentially contribute to hyperkalemia.
Then being proactive about potentially monitoring those patients would be important.I mean, one thing you could do also for elective procedures would be decide to stage or split them into parts.You know, so it's trying to minimize the amount of anaesthetic time in one anaesthetic event.
So that was actually kind of an interesting side benefit that came to the Greyhound community out of this study was that we started promoting patients to have shorter anesthetic procedures more frequently for dental care.
And so overall, their oral health got better.Yeah, which is an interesting shift because I think traditionally if you're scared of an anesthetic and a greyhound, you're going to go, well, do it as infrequently as possible to avoid risk.But as you say, inevitably that means longer anesthetics because now you've got to do all the stuff that you wanted to do in one head.
And based on this, may be safer to say no, let's do it frequently and do a 40 minute procedure and then bail and then come back in a while and do the the rest of it.Yeah, exactly.And, and also I think over time, as you're working with the same patients, helping guardians learn to or feel more comfortable with the idea of, you know, every year doing a proactive dental procedure to maintain and keep the mouth really health as healthy as possible.
So that you're of waiting having prolonged period of time that they're going to have to be under anesthesia for extensive intervention.Just a reminder that you can listen to the full episode, including treatment of severe hyperkalemia.
At vvn.supercast.com.Or give us a shout if you want the show notes for this entire series that will recap all of the important bits and give you a clear treatment guide by clicking on the show notes link in the show description right here in your podcast app.

Dr Stacey Jones