[at-l] Snake Bite (a bit long)

[champion@iquest.net (Stephen P. Champion, MD)]

I can tell you that, based on his earlier posts, Dr. Buffington has
apparently treated far more venomous snakebite patients than I, so I'll
watch for his answer to this question as well, but I'll answer from the land
of "a lot of copperheads and a few rattlers".

Antivenin treatment IS aggressive - an emergency physician's definition of
aggressive may be based on the degree of tightening / loosening of the anal
sphincter.  These patients can be REALLY sick, with the potential to get a
lot worse.  Historically, antivenin treatment ("horse serum", to my
patients) has been associated with the potential for immunologic (allergic)
side effects, which we anticipate and pre-treat, and so has been reserved
for those patients showing definite signs and symptoms of significant
envenomation.  But, as Dr. B stated in his post, roughly 1/3 of bite victims
have no envenomation, and of the other 2/3 that do have any degree of
envenomation, only 1/2 of those (1/3 of all victims) have enough
envenomation and/or symptoms to warrant antivenin treatment.  In my area,
it's even less than that (Copperheads predominate).

The decision to treat with antivenin, therefore, is based on certain
indications (signs and symptoms), and not solely on whether or not the
patient was "bitten".  That said, once those indicators have been met, the
dosage of antivenin (both the old, reliable antivenin and the newer CroFab)
is fairly standardized, measured in "vials" of antivenin.  In other words,
if you've crossed that threshold, now we get out the shotgun.  I'd have to
look it up to be certain (and I do to refresh my memory each time I treat
these patients), but the initial dose of "classic" antivenin is 5 - 10 vials
for moderate envenomations, and double that for severe cases.  The dosage
may be repeated at intervals based on the response (or lack thereof).  With
CroFab, everyone (moderate or severe) gets 4-6 vials, with that dose
repeated if/as necessary.

The new CroFab has, in theory, less potential for allergic side effects than
the "classic" antivenin and may be "safer", but I am seeing reports in the
literature implying that treatment with CroFab may need to be more prolonged
to prevent recurrent or delayed envenomation symptoms.

Everything carries some degree of risk.  If the treatment is worse than the
disease, live with the disease.  If the disease is worse than the treatment,
take the treatment.  That's why we categorize and treat venomous snakebite
patients like we do.  Most patients simply don't need antivenin.

Steve



-----Original Message-----

<snip>

I've heard, and perhaps you can confirm that medical treatment with
antivenom is aggressive, that is, the type of wound is not a factor.
A glancing bite, little venom injection, or major bite are all
treated with a dosage determined by body weight. If so, I assume the
treatment is some cases is worse than the bite, perhaps unavoidably
so, perhaps due to insurance & liability issues? Comment if you wish.

<snip>

--
Arthur D. Gaudet         	"Is walking down called hiking, too?"
(RockDancer)  	                 -heard at the top of Mt Washington, NH
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