Cobra antivenin NOT required in the intubated bitten patient ?

[KMATTOX at aol.com]

For the purposes of this discussion, and for the DATA I have found, I am  
quickly coming to a theory that NO DATA exists to support use of antivenin in  
the COBRA bite, once a patient has been intubated and ventilated.   I  am 
constructing an algorithm which tends to support that use of antivenin in the  
INTUBATED patient actually is DETRIMENTAL to the patient as it introduces a NEW  
disease (serum sickness) in a patient that would have recovered in the same  
period of time WITHOUT the antivenin.     I could make a  good legal case that 
physicians and others that administer antivenin to the  INTUBATED cobra bite 
patient is guilty of creating a new damage, caused by the  treatment and not 
necessary for the patients treatment or recovery 
 
Prior to yesterday, I was prepared to defend the use of cobra specific  
antivenin, but following my attempts to find supportive scientific data through  
the literature, textbooks, the internet searches, and testimonials from this  
list server, I am now convinced that no such data exists and use of antivenin in 
 the cobra bite patient who is intubated.   
 
Kenneth L. Mattox, MD
 
 
 
 
 
 
 
 
 
In a message dated 6/30/2008 1:50:55 P.M. Central Daylight Time,  
sworrub at gmail.com writes:

 
 
NOW FOR SPECIFIC SCIENCE.   I have looked hard to answer my  rhetorical 
question regarding antivenin in this particular  case.    From everything I have 
read, and now been told from  friends on these three list servers, the most 
important thing was to support  ventilation until the effects of the bite have 
worn off.    I  have followed the conventional wisdom and now given him genius 
specific  antivenin (6 vials of the stuff).   He sure will develop serum  
sickness within 3-6 weeks.   He is now sensitized to horse serum  should he need 
antivenin in the future.   So  have I created un necessary problems by giving him 
antivenin that he really  did not need.   Could I have treated him better by 
merely  intubating him and giving him neostigmine or other drugs.    




The science is difficult because
1. the genetic expressions of  toxins between snakes of even the same species 
is not constant.  The last  time I looked the mamba for instance has 
something like 42 different proteins  (not a cobra - I know).  The Cape cobra is more 
stable and has a greater  degree of constancy - it is purely neurotoxic and a 
bite can be treated with  ventilation alone - that I have done on 4 occasions

2. the genetic  expressions of the K+ Na+ channels etc is not constant either 
- again the last  time I looked there were some 24 channels - ligand gated 
voltage gated  etc.  Thus the effects of venom on the human can ONLY be 
investigated in  the human as anything else just leads to a lot of dead dogs!  

3.  the polyvalent serum is just that - polyvalent meaning poly snakes 
injected  into horses to stimulate the production of antivenom.  The South African  
army many years ago stopped issuing polyvalent serum to the medics because  
they were causing more hassles with the serum than without it.

4. the  cardiotoxicity of these snakes is highly unpredictable in as much as 
it may  exist with a particular snake or not exist.  I have managed to treat a 
 mamba bite without the use of antivenom - I know it was a mamba because the  
victim was a snake handler from the local snake park who said "I've been  
bitten by a mamba - don't give me anti venom"  He scared the daylights  out of me 
because I have treated a mamba bite with cardiotoxicity - even  managed to 
get a PA catheter into him - the cardiac output was very high with  a non 
existent peripheral vascular resistance indicating the nature of the  
cardiotoxicity.  
I have treated a number of Cape Cobra bites without  the use of antivenom by 
ventilation - in these cases the duration of paralysis  was less than 24 hours.

5. the dose of antivenom should you need to  give it is FAR higher than the 
literature suggests
It is antivenom and has  to be given ml for ml as an equal dose for the 
amount the snake has  evenomated.  A minimum dose for a mamba is as high as 70 mls 
and may be  as much as 120 mls.  Disection of the salivary glands in an adult 
snake  indicates such volumes

6. the snake's quarry is usually small rodents  wherein the toxin will stop 
the rodent within moments.  It will inject  according to it's needs if it is a 
full defensive strike it will inject a  large amount - Children usually have 
no chance but should they get to hospital  then there is NO paediatric dose for 
the reasons above

7 the effects of  snake venom on the human can ONLY be investigated in the 
human.   Interspecies differences do not allow for anything other than 
generalised  guesses and dead dogs.

If you want the references for this lot then you  will have to wait as I left 
'em all in SA




>From what I have read in the past 24 hours I really really cannot find  
scientific justification for giving the antivenin once I intubated  him.   Because 
it had to be brought in from a distant city, the  antivenin was administered 
several hours after the bite  exposure.      
 
Can the intellectual clinical scientist on these  web sites give me ANY 
science to support this continuing urban legend of  giving antivenin to poisonous 
snake bite victims like this one?
 


I would agree with that with some caveats.

1.  If the toxin  is purely neurotoxic (elapids - cape cobra, ?King cobra) 
then treatment is  simple ventilation without antivenom

2. If the toxin is neurotoxic and  cardiotoxic (elapids - Black Mamba 
(dendroaspis polylepis rings a bell  - probably the wrong one)) I would give 
antivenom because the cardiotoxicity  can be devestatingly fatal and if the toxin is 
difficult to displace from the  receptor then real trouble is in store because 
the antivenom may be of limited  use.  The real question is when to back off 
and give the  antivenom

3. If the toxin is haemotoxic (back fanged species) I would  give the 
antivenom.  I have seen a patient start to bleed from a  boomslang (treesnake) bite 
which takes many hours to work and the antivenom  has to be flown in from 
Joburg - the bleeding switched off in moments of  administration

4. if the toxin is cytotoxic (viperidae, crotalids) I  would give antivenom 
as again the consequences can be grave although the  antivenom might not reach 
the toxin but it will stop systemic  effects.

This all presupposes - 
1. the snake has been properly  identified.
2. it has, actually, evenomated.
3 the patient has been  bitten by a Cape cobra  :-)










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