RACGP Rural - Amy Freeman: Hello everyone and welcome to the latest installment of our Rural Health Webinar Series. This webinar will be facilitated by Dr. Ken Winkel and will reflect on the lessons he has learnt from 20 years of on-call toxinology service work addressing venomous bite and sting queries from rural, remote and metropolitan Australia (as well as internationally).
We’d just like to start with an Acknowledgement of Country. RACGP would like to acknowledge the traditional custodians of the lands on which this event is being broadcast and we pay our respects to their Elders, past, present and emerging.
RACGP Rural would also like to thank our sponsor, Ochre Health and Recruitment. Established and still owned by two procedural GPs, they operate a network of medical centers around Australia as well as operating a medical recruitment agency that works with hospitals and medical practices throughout Australia and New Zealand to source and place locum and permanent doctors across a wide range of specialties. We greatly appreciate their support of this webinar series.
Finally, before we start, there are a few housekeeping things to cover. All participants are on mute to ensure that the webinar is not disrupted by background noise, but we encourage you all to use the chat function to ask questions and provide comments, and there will also be a few polls during the webinar. Finally, this webinar has been accredited for two CPD points. In order to gain these points you must be present for the duration of the webinar. We also ask that you complete the evaluation activity that will pop up at the conclusion of the webinar. Thank you everyone, and now I will hand over to our facilitator, Dr. Ken Winkel.
Dr Kenneth Winkel: Thank you very much Amy, and I think I will switch on my slides, sharing my screen. Okay, so hopefully everybody can see that. So welcome this evening. I hear it's a good sized audience and presumably you’re all from different parts of Australia with different experiences, lesser or more, in respect of envenomation management. So I will try to tell you some stories, provide some education, and hopefully have a conversation with you about this very broad topic. We could spend a lot more time talking about various issues around the management of all the different bites and stings, so this will be a broad sweep, but particular focus on the issue of snake bite. But particularly reflecting on some of the lessons I've learned from my time as an on-call consultant over the years where it's a never ending story, the understanding and the optimal management of snake bite and other venomous bites and stings. Not just because each creature has its own venomous complement, but because each particular story has its own quirks. But there are broad themes, broad principles, that we can discern that perhaps will help you when you come across a case, whether it's a bee, wasp, ant, tick, snakebite, land snake, sea snake, or fish or other creatures. So the broad principles that you can be aware of, without knowing all the fine grained details of every creature, and then hopefully that will prevent you running into trouble (and I can assure you that even experts from time to time can come into some grief). But provided you apply the broad principle – to be safe, to be conservative – then you should really minimize the trouble that you might run into. And so this, I mean this title, is a little bit tongue in cheek, but actually, we will touch on each of these particular topics because they do tell us a little bit about venomous bite and sting management and risk management. So hopefully you're not too phobic about seeing some creature features, because we’re certainly going to feature a few of those today.
For those of you who are not familiar with my story, well I’m a University of Queensland medical graduate, a fellow of the Australasian College of Tropical Medicine, and I've done a PhD down at the Walter and Eliza Hall Institute after I completed my internship at Royal Brisbane Hospital. After I completed my PhD in immunology I spent many years as the Director of the Australian Venom Research Unit of the University of Melbourne, following in the tremendous footsteps of Struan Sutherland. And as part of that time I was a consultant to CSL now known as Seqirus, various poison centers, and the Diver’s Alert Network Asia Pacific. I’ve spent time teaching into various courses including, if you know, the Remote Vocational Training Scheme for rural remote GP trainees (perhaps some of you have heard me before – hopefully I won't be too repetitive if you have), and the old Victorian Medical Postgraduate Foundation lecture series then turned into the Health Education Limited series. I like to talk to the first aid providers, the community outreach, very important part of the story of envenomation is what happens pre hospital. I have experience with the FirstAid4Life people and the other primary health care providers. The College of Rural Remote Medicine, I’ve worked with my colleague Bill Nimo, the emergency physician. Some years ago, we developed the TelleTox module. If you've ever seen that in the ACRRM Romeo Site. I'm not sure that it's active anymore, we haven't updated that for a while. Sunshine Health in Queensland, we've had courses with them. The EMcore people. And various other places, including I particularly enjoy teaching into the hyperbaric medicine, the diving medicine community, because there's always something interesting that will come out of the audience, and hopefully I'll hear something interesting that can educate me from your experience this evening.
And of course I followed on from Struan Sutherland who over many years made so many contributions to the understanding and management of venomous injury in Australia, but particularly the, bequest really, of the pressure immobilization technique, combining firm pressure bandage, immobilization, and splinting to block the movement of venom from the peripherally, centrally, through the lymphatics, to stop the clock essentially – give us time without applying a tourniquet – so safely blocking the movement of most venom into the central circulation, giving time for movement of the patient, assemblage of appropriate management, assessment of the signs, the symptoms. So we may talk about that with the Q&A. There’s lots of issues embedded in there and how you can make mistakes. But, in general, as soon as possible, the patient should get pressure immobilization, that’s pressure bandage plus immobilization, ideally using the lymphatic compression bandages, these newer compression bandages are way better than what is depicted here by Struan in the late 1970s, using the old crepe bandages which provide really inconsistent and unreliable pressure. So Struan gave me the opportunity and I spent quite a few years building on his legacy after university. Now I'm in the School of Population Health, working more broadly in public health.
So I guess just to kind of start off: What is the first rule of venom club? Well from the venomous creature, the point of view is to eat and not be eaten. So these venoms that we’re about to talk about have been shaped by millions of years of evolution in a kind of constant warfare, if you like. An arms race with their prey. So most of the time, the story out of this is that these venoms have great redundancy. They have multiple ways of forming toxicity, because that's shaped by evolution to knock down their prey and readily start digesting it. But some venoms are really not about pray capture and digestion, they’re about defense. So your bees, your wasp, your ants are very familiar to us as a noxious stimulus, but usually won't be a threat to life. But the whole topic of venom allergy we’ll briefly touch on, but is one which is almost equivalent in numbers and morbidity and mortality in Australia, compared to snakebite. So not to be underestimated the story of venom allergy. And there's some interesting new twists on that story with the ticks and the red meat if we've got time to talk about that.
So today, now I had listed here that we're going to talk about marine and terrestrial envenomation syndromes, and we will, but the overwhelming concentration, simply for time purposes, is to talk about the issue of snake bite. But fear not, we will talk about marine and other terrestrial envenomation syndrome but we are really constrained in time. So we will highlight that principles around management, the potential hazards and mismanagement features by using the prism of snakebite issues. And also highlight the key resources that are available to help you in the management of these particular creatures.
So first of all, I’d like to start off really by acknowledging that we have a limited understanding. Actually wherever you go, when you're probing the issue of medicine and the boundaries of medicine you will find that we have a limited understanding. So with snake bite, the simple thing of even understanding every toxin in every major venomous snake in Australia – we haven’t done that. We can aggregate, we can understand the broad toxicities, but we don't have an understanding of every toxin and we know that every single snake bite will have a mix of different toxins. So you won't have precisely the same mix of neurotoxins, myotoxins, procoagulants with any given snake bite. So that adds a little bit of complexity because every individual snakebite will represent the intersection of that complement of venoms at that point in time, with that venomous creature and that person. Their background, prior history, the ambient conditions… Is it a hot day? Have they got a hyper dynamic circulation? Or is it that this is the evening and they're sitting not doing anything, so you've got a very different circumstance? What about that snake? What has its previous activities for that day been? How many snakes? How many bites has it already done that day in prey seeking vs defense? So all these things contribute to the complexity of the envenomation syndrome. Doesn't mean we don't have broad principles, but it just says we don't really understand everything. And we find new species from time to time. We find new understandings of different species. And we can talk about some of those continuing mysteries, if you like, but just to say that back in 1929 the Medical Journal Australia thought that was it, we knew all there was to know about snakebite. There was a special edition of the journal highlighting the work at the Walter and Eliza Hall Institute in the late 20s early 30s around trying to better understand the toxins, the pathology they caused and optimize management of snake bite. So we continue, almost 100 years later on the same journey and we still haven't closed the book of venom just yet.
So the venom club that we have in Australia. These are some of the main creatures to talk about. Funnel Web spider syndrome, charismatic spider, so to speak. In general, we almost consider that a solved problem. The funnel web spider antivenom made in rabbits uniquely in the world. Very effective at stopping the progress of this neurotoxic spider bite envenomation. The pressure immobilization technique, just as relevant. So those two things combined have revolutionized the management of Funnel Web spider bite. Still, potentially a very dangerous spider, big black hairy spider, East coast of Australia. Redback spiders, somewhat more contentious, the antivenom, but still we have got a pretty good antivenom. There's clearly a debate about whether that should be given to most patients or what proportion of patients, but I think this is a relatively gentle envenomation but still neurotoxic compared to the funnel web spider.
I'll just check on the Q and A's to see where there's any problems. No, and we'll come back to those questions. So just get rid of those.
So in that arachnid club, if you like, we also have a very important topic of the paralysis tick. Now I mention the paralysis tick, not because it's killing particularly many people, it is a rare cause of death, these days. But because it combines multiple forms of toxicity in a way that is uncommon for the various venomous creatures in Australia. So tick bite can kill through paralysis, the toxic action as its neurotoxin slowing the release of neurotransmitter. It can kill through venom allergy, directly, tick paralysis venom allergy causing anaphylaxis after attachment in a sensitive patient. But also now we know there is the problem of the side effect, if you like, of sensitizing to certain glycoproteins that are present in tick saliva to mammalian meat glycoproteins, thus causing potentially lethal mammalian red meat allergy. So tick bites got a combination there. And on top of that, it also has the potential in Australia and elsewhere to cause lethal infections. Also minor local traumatic injury but the infective side, tick typhus, is still a live issue, so to speak in Australia, but in other parts of the world we have tick-borne encephalitis (not caused by this particular species), but when you're thinking about patients going overseas, travel medicine, then very much your patient should be aware of the problem of going out in Eurasia, into the countryside, the issue of tick borne encephalitis. And there is a vaccine for this infection, but in other parts of the world there are hemorrhagic fevers in Africa, in the Middle East, that are also borne by ticks. So not to underestimate the tick. And so we have, of course, with the tick allergy, we have with the bees, wasps ants and also the allergy issue, not to be underestimated but we won't reflect too much on that tonight. Then you have the various marine creatures out there, blue ring octopus, a neurotoxin – CPR, expired air resuscitation, ventilation intensive care. There is no antidote. But the good news is it's just got a sodium channel blocker that will basically shut down the respiratory drive and within 24-48 hours, if the patient is adequately oxygenated supported in hospital, they will recover without other sequela. Then we have the sea snakes, pretty much the same story as the Tiger snakes with some small variations there, but we have antivenom for the sea snake. And in theory you could use polyvalent if really necessary, but it's pretty uncommon in envenomation, but we will highlight something about that story because the first aid is exactly the same as our land snakes. Pressure immobilization, get your patient so they can stop the clock on the movement of the venom, get them to where they can be assessed, signs and symptoms monitored, antivenom if necessary. But we have some peculiarities, like the platypus – no antivenom, extremely painful and we still don't fully understand that pain syndrome. But not lethal to us, but potentially lethal to pets, particularly dogs who may harass them. Then we've got things like of course the snake bites, we will spend more time on that. That is the Coastal Taipan featured there. But amongst other marine creatures, just to mention (and we will come back to some of those of course), the famous sting ray, responsible for the death of Steve Irwin. But sting rays and stinging fish are responsible for a major burden, probably in rural tropical medicine practice. It's probably after jellyfish stings, the leading cause of hospital admissions from marine envenomations in Australia. So traumatic injury, risk of infections, big issue with the fish stings, whether it's a sting ray and there's that emergency for any abdomen or chest sting ray barb exposures. But we got plenty of other stinging fish that more tend to cause problems around the ankles and the issue of infection is really paramount there. So good wound treatment always part of the story when you're thinking about any kind of venomous bite and sting. And then corals, all kinds of marine injuries that we could spend a week on, and if you're interested in diving medicine I recommend you get into that topic because it's a fascinating world of the marine venomous creatures. But let's move on.
Okay, so other resources. So there's a very good antivenom handbook put out by CSL. This is to help guide the selection of antivenom, the appropriate use of antivenom, but it provides a wealth of education around the syndromes, distinguishing them, the use of the snake venom detection kit, ancillary laboratory investigations, and tools beyond the antivenom themselves, but mostly it's about educating the clinician in the appropriate use of antivenom. And you can get that online by this link. There are courses. I personally did the Swiss Tropical Institute course before there was one course in Australia. Julian White in Adelaide runs from time to time, a short course, over usually a couple of days to a week, covering the broad range of topics. So if you want to dive in, learn some more, I recommend that course. And of course, all the poison centers, available 24 hours a day, that's your number one resource – do not hesitate to call the poison centre to seek advice. And, of course, the poison centers have extensive, extensive resources for education on their websites too. And the Australian government, HealthDirect, has a lot of material.
Of course, basic first aid. If nothing else, apply your basic first aid principles to the management of envenomation. When we're thinking about things like Box Jellyfish sting, allergy to bees, wasps and ants, this is critical – makes all the difference. Pre hospital can make all the difference. So that's nothing different to what you already know. There is an app that we produced with CSL, now Seqirus, which you can get for free via the various app stores – this is just a little link, you can go to the Seqirus website and find the link there or go via the Google app stores. And, of course, the first aid story – continuing debates about some of the place of the different first aid. Won't get into it too deeply unless you kind of want to spend some time there, but the Australian Resuscitation Council regularly revisits and looks at the highest quality of evidence to inform the first aid recommendations. So that information is available to you via these links. And of course CSL who provide these antivenoms are available 24 hours and from time to time in the past I have rung them up to get a restocking situation organized. Particularly when you've got an unusual antivenom or you’ve got a country hospital that has a particular demand. So, CSL, don't hesitate to talk to them as well. They have their own consultant, Julian White being one of them, as well as access to antivenom if you're a hospital wanting urgent replacement of stock.
There are a variety of articles out there. This is one of the obvious recent reviews put together by Geoff Isbister out of Newcastle and his team who have been doing snake bite studies for some time now. Mostly, agree with that. The contention is about the number of vials, how late and how many, which we can talk about. Here's a couple of recent articles that are kind of raising issues there from emergency medicine from my colleague Jim Tibballs in anaesthesia intensive care. So, just like in 1929, there's actually a continuing debate about some of these things. But in the very least, pick up the phone, seek your advice from your expert consultant and be conservative, keep the patient in, monitor the patient and rather give antivenom than not give antivenom if circumstances warrant it. So, do not hesitate to give antivenom, if it's indicated. And this is another article by my colleagues out of South Australia questioning the proposal by Geoff Isbister that well one antivenom is universal for everything. Think that's a bit aggressive.
So in terms of the venom effects that we're interested in, there's always some local effects, systemic toxicity, allergy issues, and infection. So that's your broad principle for any venomous bite and sting, land and sea. But with respect to Australian snakebites, clearly we're more concerned about systemic toxicity, the risk of death from neurotoxicity, or coagulopathy or rhabdomyolysis. The major preoccupation these days has been coagulopathy from snakebite – browns, tigers, taipans. But the brown snake doesn't have really the clinically significant neurotoxicity. So if you're in an area, like I am here in Victoria, where you've got tiger snakes as the leading cause of hospital admission and death from snake bite, tiger snakes unlike the brown have prominent and potentially lethal neurotoxicity and myotoxins. The taipans in Queensland, up in the territory, just into New South Wales, they also have those similar issues. But in Victoria, tiger snake not the brown snake is the leading cause of death and it's got that complex mix of pre and postsynaptic neurotoxins, myotoxins and the procoagulants, myotoxins and the pre and post neurotoxins. So any of these creatures, I should mention, when in the right population, complicate your picture with allergy. I mentioned that, not because you expect to see snake venom allergy often, but certain groups of people, and in some of your communities, even in rural Australia, you will see people who keep snakes. I know Bendigo, Ballarat, down Latrobe Valley, Gosford, and in regional South Australia at the very least, we have people who keep snakes exotic to the locality and the state, and, from time to time, illegally, snakes that are exotic to Australia. So there is always a risk that you may have in your community, someone who has repeated exposure to snakes, snake bite, snake venom, and snake antivenom. So they've got a more complicated story and could present with a picture that’s actually mostly snake venom allergy, and snake venom allergy can kill these snake keepers. And internationally it's an important part of the story of snake keeper injury from snake bite – the allergy side of things. And your keepers in zoos in particular are a legitimate example of those keepers who have a high risk of allergy to the snake venom, who may present with venom anaphylaxis. And there can be cross reaction. I have a colleague who was bee venom allergic and got a snake bite. She had nothing to do with venoms, venomous world, but inadvertently she got a snake bite and had an anaphylactic reaction. So you can have cross reaction of people who have allergy to the phospholipases in bees, wasps, ants and some of those snakes like the Tiger snake, like the Black snakes that do also have phospholipases. It's pretty rare, but part of the story.
Infection. So the next slide of a patient who’s snakebite was complicated by tetanus. This was a patient had an incomplete tetanus immunization history and people didn't think about it. Did this person need coverage? So in theory, you can get tetanus from a snake bite in Australia. But internationally, people are more concerned with gangrene complicating necrotizing snake bite. Pretty unusual story for Australia, we're more worried about systemic toxicity, the local effects, the category number one, which are a major issue for Africa, Asia and the Americas, where they’re worried about limb sparing rather than neurotoxicity and respiratory paralysis.
We do have some local effects. Some degree of mild and potentially necrosis from some of our Black and Tiger snakes. Very unusual for anything else like the Death Adder, maybe a little bit with the Taipan but it’s really the Black Tiger type snakes that might do something like that but nothing like the snakes in Asia, Africa and in the Americans.
So as part of the learning outcomes we raised the question of snakebite hazards, its management, hazards of envenomation. So what are those kinds of things that I've seen from my experience? Well, starting back at the first European description of these snakes, we misunderstood some of what was dangerous, what was not dangerous. And depending on which period you look at, people really didn't think much of the hazard of Brown snakes until really later in the 20th century. It was the Tiger snake that was the top dog or top snake in this poster produced by Professor McCoy who was the inaugural director of the museum here in Victoria. So over time, we've come to appreciate different snakes having different hazards to humans. But still, mistakes are easy to make because we know that snakes look like each other. We have in Australia problems with the deciphering which snake is which. We've got the snake venom detection kit to help us with that. We've got broad spectrum snake antivenom to cover every base anyway.
Here's an example of a case I was called to at Nambour Hospital in Queensland. So I was called by Nambour Hospital Emergency Department about a gentleman who had gone collecting (he was a naturalist photographer) and he had gone collecting snakes and he was wanting to photograph this particular snake, and he thought he was dealing with this snake, the Keelback snake, which looks pretty similar to this snake, the Rough-scaled snake. This snake is essentially harmless from a venom point of view, the Keelback snake. This snake, very dangerous, potentially lethal, has been known to kill people. So he was in the process of collecting this snake, what he thought was this snake, and he was bitten by this snake. He thought it was harmless, he actually literally put it into a bottle for photography, and he brought it into the Nambour Hospital Emergency Department. Because when he was at home photographing the snake, which he thought was a harmless Keelback, he collapsed. Classic effect of the procoagulant venoms with Australia snakebite – pre hospital collapse. So he recovered, he was lucky, and he brought in the snake. Now there's an extra twist on this tale. So that snake was alive and well and looking at the clinicians as they rang me. They rang me particularly because, clearly he was bitten by a snake, they had the snake, the fang marks were there, he was actually oozing blood from the puncture mark. They swab that bite site, put it through the venom test and it was negative. So they rang me. What was the story here? Why did I think this guy who was clearly clinically envenomed by this snake species, why was this venom test kit telling them that it was negative? And I said, okay, this may be a case of a lot of venom present at the bite site. This snake can produce a lot of venom, decent sized fangs, and in fact they then took a drop from that little bottle that was used to put the venom into the venom detection kit for the assay, put that one drop into another bottle so they essentially diluted one in 30. Did the test and they then got a positive for Tiger snake. Tiger snake antivenom is the antivenom to use for this Rough-scale snake. So it’s quite similar, the venoms, with procoagulants, neurotoxins, myotoxins. So that particular snake demonstrated the limitations of the snake venom detection kit, which is to say if the patient is clinically envenomed, they need an antivenom, then treat the patient. You are not treating the snake venom detection kit. But the snake venom detection kit did actually then tell them, yes this is a Tiger type snake and antivenom is the appropriate one there. And this photograph of me at Melbourne Zoo is just illustrating that there are lots of different snakes that can mimic each other, that overlap. So we have many brown coloured snakes in Australia, but you can have brown species of snakes, which are not brown colored. So coloration can be unreliable – mistaken identity.
And from the title, I was talking about worms and, in theory, you can get someone given antivenom after not even a snake bite but a confusion for a snake bite. This is an example of a Burton’s Legless lizard, you may have come across them in the bush. Easy without looking too closely to think that's a snake. In fact, it's non venomous creature. It's a legless lizard and there has been, I’m aware of a patient from South Australia who was retrieved by the Royal Flying Doctor Service, who received polyvalent antivenom for a lizard bite. Because one of these creatures was actually killed and brought along. So was it retrospectively then formally identified that the patient retrieved and given polyvalent antivenom by the Flying Doctor Service in South Australia actually received antivenom for no good reason. And this raises the point that patients can present, if they think they've been bitten by a snake, quite anxious and maybe nauseated. Maybe tachycardic and feeling quite anxious, maybe get a headache, mimicking some of the nonspecific features of early envenomation by a legitimate venomous snake. And similarly, in theory, you could get some of our large worms causing that kind of problem. But it's absolutely the case that this Legless Lizard bite has triggered some clinician’s uncertainty of giving antivenom for the nonspecific features that is actually not an indication for snakebite. It's the specific end organ toxicity is the indication for snake bite.
And then there's other examples. So this is a snake that was captured, actually intercepted, at Melbourne airport. So there are people who bring in exotic snakes to Australia. This is the kind of underground zoo, so called. So there was a case I heard about from a colleague from Royal Northshore Hospital in Sydney, didn’t actually bite anyone, but a case of a man who bought unknowingly one of these snake species in a pub in Cabramatta. So this gentleman bought this snake thinking it was a non venomous Python. And he took it home, had it at home, kids played with it, and one day, it just was not behaving as it normally did. He thought okay there’s something wrong with the snake and he took it to the vet. And the vet said, well, I don't know what species of snake this is, but I do know this is not a non venomous Python, this looks like a dangerous venomous snake. So he called the zoo, Taronga Zoo in Sydney, and a keeper came out and identified the snake as Russell's viper, a very dangerous Viper from Asia, for which there is not a standard antivenom kept here in Australia. It’s only some research laborites that may have some of this exotic snake specific antivenom. So that is just an exemplar of how confusion in identification of species can occur and it potentially could be very dangerous in Australia.
And there are some other examples. One way more banal, but still potentially lethal, there was a case of a gentleman who apparently was bitten by what in the textbooks is regarded in Victoria as a non venomous snake – the Little Whip Snake in Victoria, and this gentleman died. It was February 2007 in Victoria after being bitten by this extensively non venomous snake. So what does that mean? Well, actually I did some venom testing from a sample from that patient and it was positive for Tiger type snake. So the snake was actually literally thrown away, so we'll never know, but ostensibly he identified it as this Little Whip Snake and in theory, he could have had a venom allergic reaction. And so there was the risk of even ostensibly minimally toxic snakes triggering potentially lethal allergic reactions. And there are past cases in Australia of definite fatal venom allergy. It’s pretty rare, but in the snake keepers/collectors population, there is a risk of a fatal allergic reaction even potentially to some of these less toxic snakes that otherwise would be regarded really as harmless.
And there has been a case written up in the textbooks, and I think was in the Medical Journal of Australia, of another snake that mostly the snake experts will tell you, you know it's mostly harmless. So this is the White-lipped Snake here in Victoria, kind of alpine type snake. And the case in the textbooks was of a, an example of this snake, that bit a woman and the patient ended up in Wangaratta Hospital with a basically a tiger type snake envenomation. They literally had a snake and confirmed that this was a case of systemic toxicity from what had never been recorded before, as a cause of systemic toxicity. People have done venom studies, molecular studies recently and demonstrated the congruity, if you like, between this particular snake’s venom and that of the tiger snake and tiger snake antivenom was the appropriate one which was given. But most of your snake keepers will tell you oh now, this is harmless like a bee sting. And it’s a small snake with very little venom, but in the wrong size snake, the wrong size patient, the right location, the right bite, potentially dangerous. So this is just raising the question that there a range of snakes that you might otherwise not hear much about but in the wrong circumstances can be dangerous.
You may have heard of this case. Another case of mistaken identity. This man, really a contender for the Darwin award, was bitten nine times (and he was aware of it), nine times by the most toxic of our black snakes, the Mulga snake. So the problem is this Mulga snake, he thought, just like that guy in the pub in Cabramatta Sydney, he thought he was dealing with a non venomous snake and he had drunk some alcohol – too much amber fluid – so his judgment was impaired. And he had nine bites I think it was from this snake, which he collected taking it as a favor he thought to the local pub, keep it in the terrarium they had there – he thought that would be good, have a Python for the pub. So he ignored the fact that he was bitten was multiple times, and he was bitten by the most venomous of our black snakes. It's chock full of these inflammatory venom's that digest the muscle tissue, cause rhabdomyolysis and it’s very unusual to cause life threatening neurotoxicity, but certainly rhabdomyolysis quite a well-recognized feature of the Mulga snakebite. So he spent seven weeks in a coma and had to have dialysis for his renal failure after incredibly severe case of rhabdomyolysis which in unprecedented complication, meant that he needed left arm amputation because of the continued oozing and problems with the rhabdomyolysis. So very unusual, but just to illustrate that we can have some severe complications and patients can be their own worst enemy in misunderstanding the nature of the snakes, and even doctors can make that mistake.
So these are different stories. One of the Northern Territory woman definitely bitten by the leading cause of death from snake bite Australia, the Brown snake, but she thought oh, it’s only a flesh wound, just a scratch. It’s not a bite, proper. So she continued to make a cake until she started to feel unwell. She could have collapsed at home and died. And people don't appreciate that Brown snakes, the bite site may actually be practically invisible and you're not going to see a complication necessarily there at the bite site, even in a fatal case. And this gentleman here was bitten by Red Belly Black snake’s decapitated head, not the first decapitated head that can cause envenomation. And again, people underestimate the fact that snakes, even when they're deceased, decapitated, have that biting response which can cause potentially a lethal envenomation syndrome.
Pre hospital management – the patient, it’s a very important part of the story. How do we first get first aid? But ambulance services, Rural Health communities, Rural Health Services sometimes misunderstand what is completely adequate first aid. And we can see here, incomplete pressure immobilization. And here is this patient from Wodonga hospital, I think, who was bitten by a Tiger or Copperhead. Here he is in the in the ward, still got his boot on, incomplete first aid, see those two different bandages. So we still got a long way to get the message out to our colleagues about what is the full appropriate first aid for some of these snake bites. And then, of course, it is a challenge.
This is a post mortem photograph from the Victorian Institute of Forensic Medicine, illustrating post mortem signs of pediatric Tiger snake bite. This was a fatal case unrecognized antimortem. I ended up in the Coroners court in Geelong, talking to the court about the management but also the recognition and the difficulties you can initially get, particularly in children who may not recognize they’ve been bitten by a snake. And the progression of the syndrome over hours, particularly with a Tiger snake where you may have complications predominantly of neurotoxicity that may take 10 or more hours to be obvious. This child died in his sleep of neurotoxicity from Tiger snake bite that was unrecognized and he was in Apollo Bay Hospital but unfortunately, there was no story of snakebite. So in children who suddenly become unwell especially with a collapse, on an afternoon in a Tiger snake area, just take the time, have a good look good, could they have a bite site? What about could they have coagulopathy? Check, ask questions, be aware.
And this is another case, this is a kind of the Death Adder. So most people think about snakebite in Australia, they think coagulopathy, neurotoxicity and they almost use coagulopathy as a proxy for envenomation. Because we have this dominant story of the Tiger and the Brown snakes really leading the cause of death from snake bites, where they mostly have some degree of coagulopathy as a lead indicator, early (within hours) sign of snake bite. But the Death Adder, and this is actually a snake found outside of its normal range. This was a case from a snake keeper in Ballarat in Victoria, where you don't have Death Adders in the wild. So this patient presented, this was photographed from Royal Melbourne hospital, where the patient ultimately end up in the intensive care unit and given Death Adder antivenom. But the story is that if you're expecting coagulopathy as your sign of early snakebite, well, you won't ever see coagulopathy with, with most species of Death Adder. And if you're thinking that that's the indicator of toxicity, and you don't see it, sometimes people can then not appreciate that this patient may go on to, within 5-10 hours, respiratory distress and asphyxiation from the pure neurotoxic Death Adder envenomation which combines the pre and postsynaptic neurotoxins that can be a cause of death outside of the other issues with other types of snakebite. So be aware, you may not see this classic two front fangs of the bite site, you may see just little puncture marks or nothing much at all. This is a classic Death Adder bite site but don't expect necessarily to see all those punctures or much puncture signs at all. Certainly you can get a wide variety, even with your Tiger snakes, of what the bite site looks like. And I was rung about this patient by George Brakeberg initially because the hospital in Ballarat was telling him, who was kind of coordinating aeromedical retrievals I think, on that Friday night, that the hospital didn’t have any antivenom for the Death Adder. And this would not be unusual for rural Victoria community that doesn't necessarily expect to have Death Adder bites in their community, but Ballarat has the wildlife park there that has Death Adders.So I was aware that the hospital should have death adder antivenom. He was saying, look, they don't seem to have it, so I spoke to the consultant there in the emergency department who was seeing this patient who had progression of neurotoxicity and he said, no there’s no anti-venom here, and it turns out that this patient was taken to Royal Melbourne Hospital where they had death adder antivenom, and yet that hospital did have, at that time, death adder antivenom, but I didn't have it in the emergency department fridge, the had it in the pharmacy department. So miscommunication by the emergency department staff about where was that stock of antivenom, and they just didn't talk to the pharmacist – it could have saved a trip down to Royal Melbourne Hospital. In the end all went well, but just to highlight the fact that sometimes even the consultants might not know where the anti-venom is or what type in a given hospital.
This is a contrasting case from a regional center. Mark Zagorsky called me some time ago, we had a talk about this potential snakebite – wasn't clear, but plausible story for snakebite – so we put the first aid, moved the patient on to a centre that had the appropriate antivenom. And lo and behold, no venom detected – nothing happened. And that is the case with so many just normal potential snake bites in Australia. Relatively dull for your clinician, but you have to do this because, every now and then, there will be a progressive severe case of snake bite. So no harm whatsoever in doing the appropriate first aid to get that patient safely moved to a center that can assess and treat the patient if they progress to an envenomation syndrome. Sometimes there's no obvious history of snakebite even though they are envenom.
So, to summarise I guess, the picture of how to kill your snakebite patients – just some ways of highlighting here I guess, very concisely, some of the lessons I've learned about how to kill a snake bite victim. Well, people might not even think this is a snake bite and there have been patients admitted to hospital with complications of coagulopathy from snakebite where nobody thought for 10 hours until one of the anesthetists in the intensive care unit said, “Could this be snakebite?”
Inadequate first aid. We saw some examples of that. It's not stopping the clock effectively on the movement of venom. Or under appreciating the fact that when you remove the first aid suddenly things may transform and change. So there was a patient from Rockhampton Hospital some years ago, where this patient literally stepped on the snake out of a car, perfect first aid, fully stopped the clock on the movement of the venom, came into the emergency department, no signs of snakebite, no coagulopathy. Okay, let's take the first aid off. Straight away the patient deteriorated. So be aware that venom can be very securely sequestered by this lymphatic compression and immobilization. So you'd be very careful that you're ready for things to change when you remove that first aid.
Inadequate antivenom. Well that's a debate, in terms of the number of vials these days, it's an ongoing debate. But in the very least people should be aware of what the principles are of when you give antivenom, do not hesitate to give it when it's indicated. And talk to the experts – if you have any questions, any doubt, pick up the phone, 24/7 they're available.
Inappropriate antivenom. Antivenom too late. Remembering that neurotoxicity can progress well down the track. So patients have died in Australia because there has not been an appreciation of the dynamic nature of the signs and symptoms of the complications. They put too much emphasis on the initial presentation, where they may be nothing to see. But if you've got a purely neurotoxic venom, like a death adder bite, 10 hours later this patient may be in respiratory distress. And particularly in rural and regional Australia, you may not have antivenom, and it may be very difficult to get access to antivenom late at night when the flying doctors cannot come and you have to go overland and you have the lack of staff. So very much do not under-appreciate snake bite – retrieve that person as soon as possible, rather than too late.
And there's non-antivenom issues. You can have complications of snake bite where the issue is not more antivenom. So you can have neurotoxicity that's from the presynaptic neurotoxins that will not be budged because they destroyed the presynaptic membrane, will not be changed by the presence of more antivenom. What you need to do is support them appropriately, particularly manage their airway so they don't asphyxiate, until they recover those nerves, and typically severe cases take a week or two for getting repair of that presynaptic neurotoxicity. Rhabdomyolysis can kill despite antivenom if it gets away and it's too severe.
Microangiopathic hemolytic anemia, a complication of tiger snake bite, for example, that we don't fully understand, can be difficult to manage sometimes. The pre hospital collapse, of course, is critical – the patient may have had critical events before they ever get to you.
And then don't misunderstand that dynamics of when the neurotoxins cause their complications, the mycotoxins and the procoagulants, because you can have resolving coagulopathy but yet to have the severe neurotoxicity that may be that the big problem for a particular snake bite. Or the late onset rhabdomyolysis. So the severity or otherwise of the coagulopathy or the myotoxicity or the neurotoxicity is separate – you’ve got to monitor them all and go back and go back again, because things change by the hour, even by the minute sometimes. And we've got multiple examples of how people have died in minutes from snakebite pre hospital, that died in the emergency department from complications (particularly coagulopathy problems), or they've died from late rhabdomyolysis or neurotoxity complications in the hospital.
So these are some examples, and I highlight the sea snake bite case here, because sea snake are somewhat similar in its effects to others, in that it causes neurotxicity and rhabdomyolysis (not much about coagulopathy though) – but that's a snake bite that can readily be shut down if you like by the use of pressure immobilization technique. So the most recent fatality was in the Northern Territory back in 2018, when it was a worker on one of these trawlers who was definitively bitten, but for some reason the first aid didn't get appropriately placed or something went wrong, so that patient I think didn't even make it to Darwin. So do not underestimate the importance of early and effective complete first aid. And even in Newcastle – deaths can occur in the backyard of Geoff Isbister, the guru of the Australian Snakebite Project.
So, to summarise, to reiterate. Snakebite – if in doubt, seek advice. Definitive management is antivenom combined with intensive care management, monitoring, ancillary treatment (particularly for neurotoxicity and coagulopathy). So if you've got a suspicion, admit the patient, pick up the phone, seek advice, and get the patient to where there is the laboratory facility and the antivenom, a physician, nursing, capacity to diagnose and manage the envenomation, it's complications, including the possible antivenom anaphylaxis. So the treatment itself is not without harm. Although these antivenoms are typically pretty safe, pretty effective, a lot of use, but still the risk of a reaction to this foreign antigen – mostly horses, but as I mentioned, the funnel web spider antivenom made in rabbits, very low risk of acute allergic reaction, but some of the larger antivenom such as the polyvalent taipan and the tiger seem to have more of a risk of an acute adverse reaction. Brown snake, much lower volume, less common, but still, potentially there.
So these are the snakes where we have antivenoms. And we have the polyvalent as well. And the sea snake antivenom. So when you're thinking about which snake antivenom to choose, depending on where you are, there's two different advice. So, Victoria recently has started up a trend of everybody who needs antivenom gets tiger brown combo – that covers your bases immediately. But in other parts of Australia it's a bit more complicated, given that you've got any one of these type of snakes. So think about where you are – What are the snakes? Think about the clinical features of your patient, which will help you decide which antivenom. And you can also use the snake venom dedection kit which I am a big fan of. It's a tool that’s unique to Australia – helps you decide which antivenom to give, but it does not tell you to give antivenom. But there's some controversy about the risk of misinterpretation of what is potentially a very, very useful part of the envenomation management kit.
Noting, of course, if you've got a patient who's got a history of horse allergy, high risk of acute adverse reaction, but it's not a contraindication.
This is just giving you a picture of where Australian snake bites here (with neurotoxic, coagulopathic features, myotoxic features, but not so much the local cytotoxicity) fit in comparison with other parts of the world (where they’re much more concerned about myotoxicity and cytotoxicity – but they can also have some of these other problems).
This is another way of putting it – looking at the neurotoxins, the pro- and anticoagulents, and the mycotoxins depending on which species. But if you look for coagulopathy, neurotoxicity, myotoxicity, in all your potential snake bite patients, that will cover it.
The complication is that the initial neurotoxins tend to be simple blockers – on and off – blocking the postsynaptic nicodinic receptors, and they are followed by the slower destructive action of the presynaptic neurotoxins. And antivenom won't help you when that slower destructive action of the presynaptic phospholipase is happening. So you want to get in, monitor your patient for the earliest signs of that post junctional receptor blockade, because that's the easiest to reverse with appropriate antivenom. And so you keep your eyes on the eyes, literally. And this is an example from Royal Melbourne Hospital of the complication of the late treatment of a tiger snake bite, where this patient had persisting ophthalmoplegia for months, which can occur.
And of course, not forget the risk of collapse in the presence of severe coagulopathy, particularly in the context of the procoagulent type coagulopathy, which is so prominent and problematic for taipan and tiger snake bites. Your multi-snake bites tend to have the true anticoagulents which are not so much a problem.
So part of the challenge is, what does a bite site look like? Is it painful? Inflammatory? Not necessarily. This is a photograph from a television story about this bite of a sea snake, which was unrecognized by the child who was bitten, and unrecognized initially by the ambulance staff and the treating clinicians in Western Australia. So don't necessarily expect a history of a snake bite – that’s another little trick – the patient may tell you they didn't see a snake at all, it couldn’t be a snake bite. You still need to pick up the phone, seek advice, in case of that risk.
And this is where we get to September 11. So two stories of September 11 as we count down towards finishing the discussion here. So, this gentleman was a snake expert Joe Slowinski. Died 2001, September. So here's a kind of poignant photograph of him, photographed on September 10 2001 the day before he was bitten by a highly neurotoxic relation of our Australian snakes. And this guy was known for his work on the mountainous reptiles of Burma, Myanmar. He was up there, looking in remote locations for more of these reptiles, which he was an American expert on. And this is a note that you can find online, in fact, there is a book about the story of this character and his death. Joe Slowinski PhD in reptiles and herpetology. So he, this is the story of how he was bitten in the remote northern mountains of Burma and he was bitten at 7am on the 11th of September 2001. Whilst events are happening on the other side of the world, he was bitten by a snake, which he, as a snake expert, initially misidentified and he ignored initially the snake bite. It was in fact this very dangerous neurotoxic Bungarus Multicintus or the multi-banded krait, known as a killer in Asia. And so this story was written down by a contemporary witness standing beside him when he casually picked up this particular snake on the assumption that it was a non-toxic mimic (remember that mimic story that we had from Queensland), on the assumption that this snake had already allegedly bitten his assistant who caught it without ill effect, no real effects. Now he immediately recognized actually his mistake, but he couldn't detect any abrasion. So he sat down to breakfast with no first aid – could not detect an abrasion – so the same story we hear again and again with snake bite in Australia. And this is the snake expert. And he had a nap and then noticed the tingling in his muscles and then they tried to get help, but it was a very remote location and ended up they couldn’t. Later that day, respiratory distress, CPR, 26 hours of team CPR, tried to get a helicopter. There he is – this gentleman – literally with his inadequate first aid from a highly dangerous neurotoxic snake. Remarkable how the expert had such inadequate first aid. And ended up, 24 hours or so later, respiratory support could not keep things going and he died. So even experts can make mistakes and be blasé about the risks. So don't underestimate, even though it looks like it's not a serious case, because the complications may come later. And do not underestimate the power of appropriate early first aid.
Now, as it happened, I was called on September 11 about another snake bite. I was called from Miami Dade County in the United States. I wasn't called about the Burmese case (obviously nothing could be done there, wasn't an Australian snake). This was a case of a Papuan Taipan bite in Miami Dade County, Florida. So we could spend time talking about it, but basically Florida is a hotbed of exotic creatures – I'm not sure I haven't seen the Joe Exotic documentary, but I suspect he's in Florida, because it's a hotbed of exotic animals. And this guy was sorting, as an importer, exotic snakes, a Papuan Taipan, and was bitten by on September 11. So the problem of course for him is that he had a serious neurotoxic, coagulopathic, myotoxic Australasian snake bite and they used up the Florida supply of CSL polyvalent type antivenom. And so here's the bite side, wrapped up with the pressure bandage, in the intensive care unit, and he had a rip roaring taipan in envenomation, and so they got on the only fight over the United States on September 12 from West Coast to East Coast CSL antivenom. So he did well but by coincidence that was another potentially disastrous Australia snakebite in America on September 11.
And I raised the taipan analogy in the title. So I’ll just mention, when is a taipan bite not a taipan bite? Well, I saw a patient in Royal Melbourne hospital – I heard actually about in the media before I saw that patient that day. He was bitten by an inland taipan, so the most toxic snake in the world, and from the media story I thought, okay, this guy's gonna have a serious neurotoxic or myotoxic envenomation picture. I went into the emergency department, I saw him, and in fact, he was alive, well, talking, and had no antivenom. He had acute anaphylaxis to this taipan bite. So he was a snake keeper – one of these classic characters – been bitten by other snakes before, had some allergic reactions, but had never been bitten by a taipan. And so there was all this expectation that the taipan envenomation was going to be manifest as a really serious case of toxicity and in fact he had no toxicity. He had very mild, local effects, but had this systemic anaphylactic reaction, which was well managed and antivenom was not required. So, not always is it a case that a serious highly toxic snake bite is manifest as a toxic problem.
And just in the last couple of minutes, marine species. Many things we could talk about there. The big killer – multi-tentacled Chironex Fleckeri, box jellyfish. We've got an excellent antivenom. Pressure mobilization is not relevant. Really it's CPR and analgesia which may be serious narcotic analgesia for these patients. And just to mention the Irukandji syndrome. It’s a much smaller, tiny, four tentacled type of box jellyfish, rather than the 60 tentacled type of box jellyfish, which we know less about the venom, we don't have a specific antivenom, but we do know it causes something of a syndrome like the funnel web spider with massive release of neuro transmitters because of a sodium channel toxin that facilitates particularly the release of noradrenaline, the sympathetic neurotransmitters, just like in the funnel web story.
So this is a story actually from Thailand. Just to illustrate that the story that I brought to you of some of our venomous creatures, clearly, and you've got Australians or yourself indeed traveling outside of Australia, things that we think are this quintessentially Australian like the box jellyfish, well actually folks, these creatures, if not the same species, certainly a very similar species with a similar toxic profile present in other parts of the world. So in the Indo-pacific we have sea snakes, Box Jellyfish, Irukandji, these little jellyfish with the four tentacles. We also have the stone fish. So this child, an Australia Melbourne child, was stung and almost lethally envenomed off Koh Mak in the Gulf of Thailand some years ago, more than ten years ago. And the story here was ultimately a successful story but there wasn't any antivenom available locally. And he had some local complications. There we are – this is photographs from when he presented like 10 days down the track to Royal Children's Hospital in Melbourne. Lots of inching here, so you can get an infiltration from the cellular immune response to the embedded tentacular foreign body material. So he had tremendous pain and itch from that secondary reaction, which is well treated with steroids topically and orally potentially. So he ended up with a complication, which can occur. But the moral of the story was that his father, a journalist, really crusaded to improve the local public health signage and provision of things like vinegar and stinger suits so that people can know more locally, whether they're tourists or local people, about the hazard in their waters (as we do in Northern Australia, but was not typically present in Thailand). So there he is 10 years or less than 10 years later safely swimming.
And so the story in Australia – stinger suits, stinger prevention by nets, vinegar, not pressure immobilization, and appropriate antivenom, and/or narcotic analgesia and magnesium in the case of the Irukandji syndrome (this kind of jellyfish from Northern Australia).
And we don’t have time to talk about it, but in my travels, I was talking to some travel medicine doctors in South Africa, about a case of theirs, which came from Thailand, which was in fact the first case described of Irukandji syndrome in Thailand – of this unusual envenomation syndrome.
And from time to time, there are potentially very dangerous stingray injuries. This is from Tasmania – the most recent fatality in Australia from a stingray wound. There it is. And more prosaically you have these other ankle or thereabouts wounds from stinging fish, including stingrays, that potentially cause serious wound infections. So that's another story that I like to emphasize – that GPs, even rural GPs, may see quite commonly the infective complications of these marine wound injuries. And you can get all kinds of things like sponge injuries, a little spicules getting in there that need steroids (we could spend all day on that).
Funnel web spiders – we’ve talked about that. Red back spiders – local effects prominent and simple analgesia, oral analgesia, and then maybe red back spider antivenom, which is pretty safe and effective for most people.
Just to say that even today in the 21st century, we find new species of dangerous snake. So this is a photograph of a reputed new species of taipan that was discovered in Western Australia. The good news is that taipan antivenom seems to work. But there we are, 21st century and we didn't even know we had another species of taipan.
So I'll just go to Q and A's.
Centipedes – are centipedes poisonous? Potentially venomous, but in Australia, painful, but the stings are not a cause of lethal envenomation. But certainly the centipedes in Asia can be quite toxic.
Lyme disease. Well, that's another topic that we could spend time on. I guess the controversy you probably all know about is that in North America, hard body ticks can harbor this vector of Lyme disease, this little spirochete. Is it here in Australia? Well, people have looked hard for the exact spirochete, haven't found that in Australian ticks, but have found other spirochetes. Could it be that there is a Lyme-type disease that’s not exactly the same? I think it's quite plausible – that is a subject of active research, lot of debate with the Commonwealth Health department. Certainly we know that tick point infection is a potential killer in Australia. So these ticks do carry infections. They do carry spirochetes. It's quite plausible, but as yet, we can't call it Lyme disease.
Sea snakes. Very uncommon. Fishermen. Children. No deaths in Australia in the last hundred years really until that case of that trawler fisherman. So unique issues for retrieval. Well, it's another neurotoxic snakebite and that's the problem that can kill these patients rapidly. Days later they could have myotoxicity. The last death of an Australian child was actually in Malaysia, and I think the late 50s or early 60s, and that child died not a neurotoxicity but of rhabdomyolysis.
Death adders in Western Victoria? Well there used to be, but not that we know of anymore. There is a species of snake called the bardick, which looks somewhat like a death adder, and reacts somewhat similar to the death adder in the venom detection kit, but we haven't had death adders as such in Victoria as a native species for 100 years. But certainly death adders repeatedly turn up in all parts of Victoria with snake keepers.
There's another question from David, or comment… Russell’s Viper – commonest cause of death from snake bite? I haven’t got the last part of your comment… okay, here we are… spent several years in Bangladesh… Yes indeed it’s a very dangerous snake in Asia. So we are fortunate. Most people have who exotic dangerous snakes legitimately in the zoos these days tend to have very few problems. Historically, a few decades ago, there were multiple exotic snake bites, not from Russell's Viper, but certainly from rattlesnakes cobra snakes, in different zoos – Taronga Zoo, Melbourne Zoo and the Ballarat Wildlife Park, amongst others. So that's kind of another an interesting area – the exotic snake bites. But if you have an exotic snake bite from one of the zookeepers, still you're looking for neurotoxicity, myotoxicity, local complications, and the possibility of rhabdomyolysis. But you need to pick up the phone, talk to your local experts, your national experts, if you need to access some of these zoo associated antivenoms.
Okay, so cross reactivity between Australia and other country’s snake venom? Yes. Interesting question. Essentially the story seems to be that our snakes are very closely related to the kraits out of Asia – small, fangs at the front of the mouth that are not foldable – so that's what the Australian dangerous snakes are, these so called elapid snakes with small fixed fangs at the front of the mouth, just like the Asian kraits, just like cobras in Asia and in Africa. So there's similarity there. There are common antigens and, indeed, there's a possibility that we can use the tiger snake antivenom for the treatment of some of these. And there's been laboratory work around that question over many years. So I think at least in that area there is a common evolutionary ancestor, but there certainly is, throughout the world, convergence of toxins on the postsynaptic nicotinic acetylcholinic receptor that reflects convergent evolution because a very significant receptor to block.
Anti-Gal antibodies from Mark… bush walks in Queensland… Yeah, I grew up in Queensland. Unfortunately, I avoided the issue. Are mammal derived antivenoms safe? Very interesting question. I have thought that this may be one of the reasons why we do get in people who have no prior exposure to horses or antivenom acute adverse reactions. Maybe it's got to do with those Anti-Gal type antibodies in patients, such as yourself, who are then reacting to the horse and mostly horse antibodies, but we don't know the answer to that. But absolutely we know that antivenom allergy is not a contradiction to the use of antivenoms. So you should regard yourself as safe. But absolutely you want to take care to prevent snakebite so you don't run that gauntlet of that particular problem.
So, Sandra asks how far up the leg do you compress? All the way to the trunk for the arm, for the leg go from the tip of the toes (or tip of the fingers) all the way to the trunk. I go past the upper knee absolutely, because you need to be compressing the maximum lymphatics, combining that with splint, combining that with immobilization of the patient. The initial studies, when this was developed in the late 70s, early 80s, certainly suggest that if you do not have full limb compression, full limb immobilization and immobilization of the whole patient, you will inevitably push some venom into the circulation. So you want to really try and do the maximum amount of compression and immobilization.
What else would be done before antivenom is given? Well, you want to do a full neurotoxic survey, you particularly want to be vigilant about the cranial nerves, the eye signs, and looking for any non specific features of envenomation, lymphadenopathy. Certainly check the urine, and check access to the IV access for the patient. Check what antivenoms you have, and certainly if they need, talking about whether you can get the patient to a centre that has better intensive care. Sometimes in these regional centers, obviously it's just you and then one nurse maybe at the best. In the Northern Territory, as I understand it, all patients in the country taken into Darwin because even if you had some antivenom, you don't have the capacity to manage the complications of things like taipan bites or the serious coagulopathy from brown snake bites. So really think about whether you need to retrieve the patient sooner rather than later if you have any question of contingency or constraint on your ability to monitor that patient and treat that patient and the complications of a patient.
Antibiotics. Generally, we don't recommend out on spec antibiotics for snake bite patients. And certainly even with your marine wounds, unless you've got a patient say who's diabetic, steroids, some kind of immunocompromised, you're worried about vibrio, then you want to be more aggressive. But if you've got any delay in wound debridement and cleaning, any question of wound infection, particularly when you think about vibrio in the context of the immunocompromised diabetic patient, you want to be thinking about appropriate antibiotics, particularly the tetracyclines, and talk to your poison centre or infectious disease physician if you've got a patient where you think you've got an infective complication there. But generally, run of the mill snake bite and most of your bite and sting patients, you don't need that. Other parts of the world, you might be a bit more aggressive about that, but certainly in Australia it’s an uncommon complication. But always think about tetanus status.
Is it reasonable to cut a window in the pressure bandage? Yes. Yes, absolutely, because you've got the rest of that compression and immobilization working for you.
Describe snake bite first aid. Well, basically (you can have a look at the links) but basically it's a firm compression bandage from the tip of the limb (the fingers just leaving the tips out so you can check the capillary return), all the way to the trunk. Combine that with splinting. Combine that with immobilization of the patient. And you really want to have compression that blocks the lymphatics. It's not a tourniquet, so it really needs to be firm, maybe you can get one finger underneath it, it should not be uncomfortable for the patient, but it should be firm.
Tetanus? Yes, always think of tetanus status. You don't need to give it if the patient's status is up to date.
What are some good courses to learn about envenomation? Well, I mentioned the Children's Hospital in Adelaide, Julian White, they run courses there. Many of the emergency medicine pre hospital management courses. St John’s ambulance. The EMcore team and others also incorporate envenomation management.
How do decapitated snakes still bite? Well they still have a biting reflex there – don’t ask me the neuroanatomy, but it still happens. So there's venom still present and indeed you can be envenomed in principle by a totally dead snake where you have the fangs. So taxidermied venomous snakes are a bit of a risk because the dried venom still can be active. And we did some venom studies to look at some decades old snake venom and it was still immunologically active and had some trace of the active toxins. So they're pretty stable, snake venom toxins.
Are some venoms transmitted by lymphatic? What is the point of compression? Well, the compression is of these lymphatic channels, the low pressure channels. It's not compressing the arterial and venous circulation. So it's not painful or uncomfortable for the patient, but it should be firm.
When's the best time to remove the bandage? After you’ve fully assessed the patient, signs, symptoms, laboratory investigation, have IV access have access, and have access to antivenom. So be ready for things to change. Most of the time it won’t but more than once patients have had rapid decompensation once the pressure of immobilization has been removed because there's been a bolus of venom that has then moved fairly quickly to the central circulation. And the big problem is the coagulents that may precipitate a cardiovascular collapse.
Yes I do recommend the lymphatic compression bandages that have the rectangle which helps you be aware that you've got the correct pressure there.
Spider bite – how long does envenomation take place. Good question. The answer is different for your funnel web or your red back. So your red back, it's not a rapid forming envenomation syndrome. So, the patient initially may not even notice the bite, but then over hours, maybe days, the patient’s pain they build up at the site, progress over the limb, they may get features of headache, insomnia, myalgias, paresthesias, small risk of a complication of myocarditis (but that very unusual). Most of the time it's about local pain that progresses over hours to days. And so that's in contrast to the funnel web, which also, they both have neurotoxins, but the funnel web spider has a neurotoxin that binds to the presynaptic neuronal sodium channel and seems to keep the channel open to facilitate the release of particularly the sympathetic neurotransmitter. So within two hours, the funnel web spider bite patient should be sweating, fasciculating, feeling very anxious and unwell as the sympathetic neurotransmitters surge through the body. And they can get hypertensive, which may be dangerously hypertensive, so these patients can get high intracerebral pressures. Interestingly, so they can die initially from that intracerebral pressures or they have a secondary risk when they've released all of their sympathetic neurotransmitters and the patient then, basically, their blood pressure drops. They may get a cardiogenic pulmonary edema as they’ve basically exhausted their sympathetic neurotransmitters. So that can occur a day or two down the track, but usually in your child or your adult female (and those are the patients that have died from funnel webs). It's within two hours you see whether there's a progression. So if your patient presents to you more than two hours after a bite from a big black hairy spider on the eastern seaboard of Australia and they've got no signs and symptoms, particularly if it's an adult, then very low risk that that’s going to be a funnel web toxicity.
White tail – cause for concern? Well, most of the time, local pain, inflammation, and that’s it. A lot of debate about whether there's more to it, but for most patients, that's it. But any patient who's got any kind of bite and sting where they may have an underlying immunocompromise, there's a risk of a complicating infection or inflammatory reaction that is more than a simple venom story that we see in the laboratory with a white tail spider. So we certainly have had a story in the past that we published in the Medical Journal of Australia about some legitimate inflammatory reactions to the white tail spider. But for most patients, not much to worry about.
Okay, just looking through the questions. When is the best time to remove the bandage? Okay. We talked about that. We’ve talked about the spider bites.
How long after red back spider bite can antivenom be given? Well, the thing is that patients may not initially complain that much. So typically, you can give it as soon as you've tried local analgesia, maybe oral analgesia, and if they have progression of pain or they've come in and they had the bite yesterday. So you can give it within hours and sometimes it can be given as late as a couple of days. It seems to be a venom that persists and many patients have had relief, even a couple of days after the bite of a red back spider, particularly when they've got insomnia and progressive regional pain.
Box Jellyfish – vinegar? No, it has not been withdrawn.
Okay. When you say horse allergy do you mean hay fever type symptoms when exposed to horses or of course if they have an anaphylactic reaction from that horse exposure? So any kind of sensitivity there may put them at higher risk of reaction to the horse antibody based antivenoms. Not much research done on it, but it's a general comment.
Okay, ambulance Victoria’s recent case of 8 year old with a lot of pain from the bandage. Well, it's possible they put too much pressure, particularly for a child, maybe. So you need to, particularly children, make sure it's firm but not uncomfortable for the patient.
Next question. I think we're getting towards the end here. Snake bite – how do you best take a sample from the bite site for the test kit? Well, someone mentioned that if you've got the compression on, then you can cut a little window out, as has historically been recommended. Or you can actually test the urine – that’s kind of second best because the highest concentration of venom is at the bite site. Third best is the blood. But the highest concentration at the bite site. You can take a window out of the pressure bandage. Sometimes you literally do not know where the bite site is – the patient’s got symptoms but it's not clear from the history, there was no obvious bite, but there was an exposure – maybe in the child outside who became unwell and has very clear features of snake bite, in which case I would really be going straight away for urine, which is pretty robust for the detection of venom but not as high signal as you get from the bite site.
Okay. Allergic reaction with hives after tick bite – would you recommend steroid usage? Potentially, but just be careful with which amount of steroid you're using.
Venom at the site without envenomation? Indeed, you can you can. You can detect venom positive snakebite but it is not an indication to giving antivenom. Absolutely. And like with the patient I mentioned, the rough scale snake bite, initially you might think, actually this is a negative test, but actually there is so much venom that it's saturated the antibodies in the test. So the venom detection test is another story. But, usually, you get a good signal that's within the range, but the signal positivity does not mean envenomation and you can still have venom actually detected in the urine and that is not necessarily an indication of antivenom, because they may have very small quantities that do not cause clinical features that justify antivenom.
To start, pressure bandages proximally or distally? Good question. There's a lot of background story there. But basically, the Australian Resuscitation Council’s recommendation is distal to proximal, covering the entire limb. Yes, theoretically, you may push the venom centrally, but that's more comfortable than compressing from the center distally where you may actually get venous congestion, and if the patient starts to move their limb that will render less effective the first aid.
What else… Okay… We I think we're in a loop here and I've gone through I think pretty much everybody's questions. I'll just stop sharing and hand over to Amy because I think we’ve gone over time.
Amy Freeman: Thank you so much Ken. That was fascinating, I think I speak for everyone – that was so interesting. Thank you so much for sharing. And just to conclude this evening, I’d just like to say that RACGP Rural would like again to thank our sponsor, Ochre Health and Recruitment. And just also want to say thank you to our attendees for joining us this evening, and just a reminder to complete the evaluation form that will pop up in the new window just once the webinar session closes – it'll take no more than a minute to complete. Also certificates of attendance will become available on your CPD statements within the next few days, but for any non RACGP members who would like a certificate of attendance please email us at firstname.lastname@example.org. And that concludes this evening. Thank you everyone and good night.
Dr Kenneth Winkel: Thank you.