A chlorechis bite question

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A chlorechis bite question

Postby sildargod » Mon Jun 21, 2010 4:58 pm

I put this here as it isn't technically a personal bite report.

Seeing Michaels earlier post, I went to look up what it looked like as I had never seen one and ran into this bite report from a hospital - http://www.njmonline.nl/njm/getpdf.php?t=a&id=10000066
Could his condition have been worsened by the fasciotomy? He also had been bitten by a Gila monster a year before. Could poor husbandry be a factor? I can only imagine he keeps other venomous and had other bites that didn't go reported, which may have provoked such a strong reaction, or is the A chlorechis bite bad enough to cause this as is?

I ask this because my knowledge on envenomation is extremely limited, and what I've read tends towards bites being worsened by incorrect or inadequate hospital aftercare.

Your opinions fellow forum goers?

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Re: A chlorechis bite question

Postby Bushviper » Mon Jun 21, 2010 6:02 pm

Well the antivenom they used was not designed for Atheris bites and its effectiveness is questioned as well. By comparison the SAVP antivenom is more effective on Echis than this French antivenom so it might be more effective on the Atheris bites as well to control bleeding.

Why the patient was intubated and kept intubated is not clear. I have an idea these doctors do not often work with snake bites and possibly over reacted a bit in their treatment.

What is important is that they tried and it saved the patient. Whether he would have died is another question entirely.
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Re: A chlorechis bite question

Postby Sico » Mon Jun 21, 2010 7:51 pm

The reasons the patient was intubated are likely to be as follows (I can only surmise as there is insufficient information in the report as to what his Arterial Blood Gas values were, and the mode of ventilation used)

The values given on his Full Blood counts show that he has extremely low levels of platelets (used for clotting), his heamoglobin (transports Oxygen) is down, as well as his Heamatocrit (proportion of percentage of whole blood products in total blood volume). He would have been acidotic (due to the high lactate levels from the kidneys not being able to excrete due to his renal failure, evidenced by his massively high urea and creatinine levels, and probably caused by a combination of Acute Tubular Necrosis, from all the heamolysed - broken down blood products, of which there was a LOT- blocking the renal tubules where filtration takes place, as well as his hypotension - blood pressure below 100mmHg). The fact that he has cellulysis, or the breaking down of cells will also contribute to the acidocis as the cell contents are acidic in nature. Cells releasing potassium etc will result in Hyperkaleamia (elevated levels of potassium in the blood), which can lead to cardiac dysrythmias, another very good reason for keeping a patient sedated and ventilated, when everything else either is or could begin to go wrong.

The patient quite quickly developed a Disseminated Intravascular Coagulopathy from the cytoheamolytic components of the venom, which is why he was bleeding internally and externally. This required significant transfusions of whole blood and blood products to attempt to control the heamorrhage, and with large transfusions you stand a chance of getting something called Transfusion Related Acute Lung Injury, which is very similar to Acute Respiratory Distress syndrome, where the lungs swell and fill with fluid (another complication caused by the kidneys not excreting fluid is that it backs up into the lungs and causes pulmonary edema, in this case it would likely have been treated partially using Positive pressure ventilation techniques). Another complication of blood transfusion is that you loose something in transfused blood called 2-3DPG (2-3 Diphosphogluconate which aids in allowing oxygen to move from the blood to the tissues) and it takes a while for it to return to normal values. Getting rid of the acidosis (in the form of carboxilic acid or CO2) in a case like this is best done through various methods of mechanical ventilation as well as dialysis (and the administration of certain drugs).

Another reason the patient may have been sedated and ventilated is as a form of controlling the pain, they do not mention what levels of discomfort he was in.
The only negative difference the fasciotomy would have made is to open another place for him to bleed from, pretty much irrelevant, since he was bleeding internally already. The fasciotomy probably saved his finger and hand by allowing the pressure to be released under the fascia, so preventing further tissue ischemia and death due to lack of blood flow (much like a tourniquet effect would cut off the blood suply).
I'm not sure if i follow your question, with regards to poor husbandry, if it is specific to making his condition worse, definately not, if it is regards to him getting a second bite within a short space of time, perhaps. We don't know what the circumstances around him getting bitten were, and accidents can and do happen.

To be perfectly honest with you, I am surprised that he was ONLY ventilated for two days and not longer, and I think (without knowing all the facts, but from what I can only read) that they actually handled the case pretty well considering the amount of experience in these matters that they are likely to have had. Often treating cases like this has very little to do with the managing of the venom with antivenom, and a whole lot more to do with managing everything that is going wrong, because the only thing antivenom is going to do is to hopefully prevent the venom from causing so many problems, it is NOT going to reverse any of this once it has happened. Medical specialists that know what they are doing to not treat snakebites with antivenom, it is only a small and often not so important part of what can turn out to be a very complicated treatment process. There is also a high risk of anaphylactoid reactions to antivenom which is a foreign protein, being introduced into the body. This can affect the airway, causing bronchoconstriction, and more edema. In a patient in this guy's condition that is lethal. If he is vented, you have a slightly better chance of managing the problem if it starts.
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Re: A chlorechis bite question

Postby rolandslf » Tue Jun 22, 2010 9:09 am

@ Sico - Thank you very much for a brilliant response, for the first time I was able to fully understand what took place, simply because the Medical Terms were explained in terms I understood . Thanks Once Again.
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Re: A chlorechis bite question

Postby fredsmith » Tue Jun 22, 2010 10:47 am

rolandslf wrote:@ Sico - Thank you very much for a brilliant response, for the first time I was able to fully understand what took place, simply because the Medical Terms were explained in terms I understood . Thanks Once Again.

Ditto.
Thanks Sico.
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Re: A chlorechis bite question

Postby sildargod » Tue Jun 22, 2010 11:25 am

Thank you so much Sico, that does explain a lot more than I could discern from the medical report.

My question regarding the husbandry is due to him receiving 2 bites from seperate venomous creatures in the span of a year. As you say though, bites do happen, and he may have such a significant number of venomous animals that getting only 2 bites is really well done on his part.

In short then, can we conclude that Atheris bites are highly venomous? Or was this more likely a once-off bad reaction that would normally not be so severe?

Thanks again Sico, your answer was excellent and settles a number of doubts in my mind regarding hospitalisation and treatment of a venomous bite. More especially for highlighting the fact that antivenom isn't a mysterious holy grail that halts envenomation in its tracks and magically cures all ailments that have occurred (which is the impression I was under).
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Re: A chlorechis bite question

Postby Sico » Tue Jun 22, 2010 1:13 pm

No worries.

In short then, can we conclude that Atheris bites are highly venomous? Or was this more likely a once-off bad reaction that would normally not be so severe?


You could come to that conclusion yes, but there are many factors that determine the severity of an case of envenomation such as, but not limited to those i list below
- The venom/weight ratio. The same volume of venom is going to affect a mouse a lot more than it will affect an elephant. People with small body sizes/weights are more likely to have a severe reaction to the venom than a rugby player of 130kg.

- They type of venom (and all its funny little enzymes, which differ between species, from snakes to spiders to scorpions etc) will affect different people differently. Much the same as any allergen (something that causes allergies) would affect people differently, i might get a reaction from handlng a cat, whereas you might not. Each of us responds to cases of envenomation differently as well.

- The basic type of venom (cyto-, neuro-, heamotoxic etc) will also have a different effect on different people. Someone who is healthy might recieve a relatively mild bite from a Naja sp, and they will have only mild neurological symptoms, I might recieve exactly the same bite, but due to my chronic asthma, the likelihood of me developing a severely compromised airway is significantly higher. The same goes for someone like a Heamophiliac (basically someone who's body lacks the proper ability to clot, for various reasons) getting bitten by a Boomslang, would be in a worse off position than someone who does not have this problem. Or would they? Perhaps the chronic medication they are on, would make the heamolytic enzymes in the venom less active. We don't know.

- Where on the body the venom is injected. A "minor" bite from a puff adder on the outside edge of the foot, is hardly as serious as the exact same bite on the shoulder. Not purely due to the tissue destruction, but there are that many vital underlying nerves, muscle groups and vascualr bundles that will be affected.

Due to these reasons, when you are told about envenomations, you get given a list of symptoms that can accompany the different venoms when injected into the body. Not ALL of these symptoms have to be present, and there being only one or two symptoms as opposed to a whole list of them, does not make an envenomation any less serious. For example, if we take the Naja bite, we know that the symptoms can include dizziness, blurred vision, cardiac dysrhythmias, parasthesias (abnormal sensations like pins and needles), abnormal pupillary reflex, paralysis of various muscle groups, anasthesia (abscence of senstation), nausea and vomiting, unconsciousness and so forth. A patient that only exhibits abnormal respiratory function is a lot more serious than a patient that complains of blurred vision, nausea, dizziness and parasthesia of the affected limb.

What it boils down to, is that there is an almost infinite variety of variables when it comes to cases of envenomation, and each one needs to be looked at individually, and judged on its own particular merits. Yes we have case studies like the above mentioned, that can be referred to and used as guides, and we have lab studies where venom was tested on mice to give us Lethal Dosage values etc, but in the lab studies, all the mice were the same, they weighed the same, they ate the same, they looked the same, they were all 100% healthy and they all got injected the same way, with the same amount of venom. That is the only way you can be sure to get comparative results and to be able to say Vemon X is worse than Venom Y. Unfortunately none of that happens with people, we are all individuals, so are the animals that envenomate us (from the size of the animal, to the amount of venom they inject) and thus there is no absolute "This is How Envenomation MUST be Treated" book. We do know that certain venoms are worse than others, purely becasue they are so virulent that the doasge and site of bite and all the rest can be pretty much irrelevant, but there are a number of what are popularly believed "non-virulent' venoms that have also caused significant morbidity and in some cases mortality, purely because the specific individual that was envenomated suffered a catastrophic systemic reaction.

It is very short-sighted to think, as a herpetologist, that by owning only a mildly venomous snake, that you are safe in the event you do get a wet bite. YOU may be the first statistic on that species mortality list, due to something you did not even know existed in your genetic makeup. Yes, that statement does sound very dramatic, but we know it happens, very rarely, but everything in the medical field that we know, is because it happened to someone at least once.

I have been bitten three times by venomous snakes, due to my own negligence and inexperience when i was a lot younger.
The first one was a juvenile Bibrons Stilleto snake, single puncture wound from a single tooth, on my left thumb. I spent 7 days in Garden City clinic in a lot of pain and discomfort, recieved no antivenom, only analgesics, anti-inflammatories and a lot of antibiotics because i got blood poisoning (which was probably a lot worse than the initial bite).
The second time was a little over a month later, I was bitten by a juvenile Copperhead, again on the left thumb. I was admitted again to hospital (this time Flora Clinic, as the surgeon that treated me the firs time had moved, and i felt comfortable with him) for 11 days, and i had to have surgical debridement of the wound, again recieved no antivenom, but a lot of painkillers, and antibiotics. Was the second bite more involved because it was right on the tail of the first one? Was it more involved because copperheads have a more virulent venom? Who knows.
The third bite was about a year and a bit later, when i was bitten by a juvenile Puff Adder (around the same size as the copperhead that bit me), also on the left hand, on my index and middle fingers. I recieved three bites and 5 puncture wounds, all with venom injected. I decided to watch it and see what developed (although the pain was intense, my old man would have seriously *#$$%$^& me up if he knew i still had some venomous snakes knocking around). There was some swelling of the bitten fingers, to the point that i could not bend them, the half of my hand with the thumb and fingers on was also very swollen. I went camping the next day, partly so my parents wouldn't see it, and also so that if it did get bad, i could claim i was bitten whilst out in the bush (oh how teenagers have the ability to concoct such elaborate schemes! :) ). After 4 days the swelling started to recede, and after about 7 days it was gone altogether. I sustained no gangrene, used no medications other than paracetamol and I have not a mark to show for my troubles. Can we deduce from this that a puff adder bite is not as serious as a Bibrons stilleto snake? most definately not, because we know for a fact that there is a marked difference in the strength of the venoms, but i put that up as a comparison of three cytotoxic bites, from three different snakes on the same place on the body on the same person, all with markedly different results and treatments.
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Re: A chlorechis bite question

Postby michael » Tue Jun 29, 2010 11:40 am

Fantastic response Sico! I certainly learnt a lot! Do you believe the intubation was necessary? Would the low blood oxygen levels have improved as the platelets that transport the oxygen were being destroyed by the venom, was the FFP not more effective. Were the fasciotomys not ineffective or even dangerous in this case? I understand the danger of compartmental syndrome but in this case increasing the opportunity for blood loss doesn’t seem like a good idea. I know the use of fasciotomy in snakebite has been a very heated debate. In no doctor/surgeon so the above questions are for my own interest and your response would be much appreciated.

Sildargod, Atheris for a long time have been a poorly studied species. The areas where they occur don’t seem to have very much reliable info on bites. With them becoming popular in the hobby and so many species now available I think we are going to get a much better understanding of how potent their venom is, from some unfortunate human "test subjects". I have managed to track down some case studies for A.chlorechis, squamiger , nitschie and also for P. superciliaris and all the studies I have seen resulted is severe symptoms. This would lead me to believe that these are highly venomous species and should be treated with extreme caution.

In this specific case the antivenom arrived 12 hours after admission and as Sico said antivenom cannot reverse damage but only prevent and further damage taking place. Antivenom neutralizes venom that is still in the body that has not begun to act on the body. This makes me wonder how much good the administering of this antivenom did. The paper does not conclusively give any indication that it was effective. Echis specific antivenom is supposed to “help” in treating a severe Atheris envenomation but then it needs to be promptly administered.

The paper also states that he was bitten while feeding the snake; I do know that there are arguments around snakebites being more severe in the case of a feeding bite. If he was following proper husbandry protocols he should not have been bitten feeding his snake, although accidents do happen. I was also told about a bite (A. chlorechis) that happened during a specimen collection trip. The collector was also bitten on the finger and the symptoms were mild, pain swelling and minimal necrosis. This case indicates that every bite may not be as lucky!
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Re: A chlorechis bite question

Postby Sico » Tue Jun 29, 2010 9:28 pm

It is difficult to comment on a case like this saying "I would have done something differently, or I would have not done what they did" as I wasn't there to see the patient myself, and I am only going on what I can read from the article, which I am pretty sure does not contain all the information, only what the author(s) thought was pertinent to their particular interest.
So, based on what I read in the text;

Yes, I do think that induced coma, and intubation/ventilation were pertinent in this case, as the initial results showed that the patients condition was deteriorating. Putting myself in the shoes of these guys, and taking into consideration that the nearest they may have come to treating something of this nature was on a blackboard back at varsity, they most likely decided to err on the side of caution, not knowing how far the patients condition was going to slide. As I mentioned before, it is a lot easier for everyone involved if you have a completely sedated ventilated patient and things go wrong, than if things go wrong and then you have to try and sedate the patient and get their ventilation sorted out whilst everything else is going wrong. A group of Doctors with more knowledge and experience in this kind of patient may well have said, "Nah, he will only go so far, and we can handle that, no need to do XYZ YET", but I still think that they made the correct choice.
FFP (Fresh Frozen Plasma) does not aid oxygen transportation. It is to add clotting factors to the remaining circulating blood, as well as volume, and is generally given with platelets (the clotting factors are needed to get the platelets to bind). The hypoxia (low blood oxygen in this case) could have been caused by any number of things, from the fact that he had an active coagulopathy, which would have made the efficiency of his blood transporting Oxygen very poor (as it would have resulted in loss of red blood cells -through bleeding- which carry oxygen, as well as damage to other red blood cells therefore destroying their ability to carry oxygen properly - haemolysis is the breaking down of blood cells), to respiratory dysfunction, either as a result of the chemical changes (acidosis vs alkalosis and all that goes with it), or pulmonary edema and as mentioned before the possibility of the Transfusion Related Acute Lung Injury (the authors do not list specific causes for his hypoxic state).
As far as the fasciotomy goes, w.r.t. it being dangerous, yes, definitely. With something as invasive as that, there is always a huge amount of risk, not only from haemorrhage, but also from infection, disfigurement, and loss of function. A fasciotomy is not something undertaken lightly, and it in a case like this the benefits need to be carefully weighed up. If you do the fasciotomy, the guy might bleed a lot, he might get infection, he might have bad scarring, but he might not. If you don't do the fasciotomy, he might lose most of his hand, and/or the underlying structures to gangrene, he might not. Most of the damage from a fasciotomy can be controlled, or reversed, gangrene cannot be, other than by cutting it off (and generally with a bit of a nice healthy border to make sure you got it all, especially when it is infected). I don’t think we can really comment on the effectiveness of the fasciotomy done in this case, since the guy did not lose his hand or any of the function. We do not whether this would have been the case if the fasciotomy had not been performed, but since he has full function, I would have to say it was successful. If the doctors waited to see whether compartment syndrome developed before doing the fasciotomy, you would have had a case of the patient now having damage to the tissues distal to the compartmentalisation, as well as haemorrhage. I think the haemorrhage would have been easier to control, than worrying about haemorrhage in compromised tissue that is now even more prone to infection.
I don't think the administration of antivenom was a shot in the dark, or that it may have been ineffective. Theoretically, if you can manage the symptoms of an envenomation, and control everything like breathing, circulation, filtration, clotting, etc a patient should be able to survive any kind of envenomation without antivenom, as the venom will eventually break down, and be eliminated from the body. Unfortunately we cannot do tests to see how long venom takes to do this, as some people feel it is unethical to do such trials on other people, and the lab animals that can be tested are invariably killed by the venom long before it has changed to an ineffective state. There are plenty of documented cases of animals like Honey-badgers that get bitten by highly venomous snakes, are ill for a few days, and then basically shrug it off. We just don't know how much time needs to pass before we can say that we have reached a cut-off time for the administration of antivenom. Logically, I would say, if the symptoms are still presenting, then the venom is still active. So in this case, despite being given a LOT of blood via transfusion, the patient was still haemorrhaging, or his clotting profiles were still abnormal, then it is still indicated to administer antivenom.
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Re: A chlorechis bite question

Postby michael » Wed Jun 30, 2010 10:13 am

Thanks again for the response Sico.

With regards to the fasciotomy I read a paper by Dart. R.C, 2004, Can Steel Heal a Compartment Syndrome Caused by Rattlesnake Venom?. Ann Emerg Med. 2004;44:105-107. From my understanding the author does not seem to support the fasciotomy route if anti venom is used as it doesn’t seem to have a better outcome for the patient. I can understand the doctors in this case were doing their very best in a bad situation and that this type of emergency is not very common or simple to treat. This is why I suppose there are so many conflicting views. If I was a Doc I would certainly hate to try to treat a case like this and like you said there are probably a lot of underlying circumstances left out of this paper.

Thanks so much for your insight, im sure everyone who reads this tread will appreciate it very much, as I did.
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