[at-l] Snakebite Treatment on the AT Part II of III

[agaudet at TheWorld.com (agaudet@TheWorld.com)]

Snakebite Treatment on the AT Part II of III

Some basics:
The snakes we?re talking about are both pit vipers (rattlesnakes &
copperheads). I won?t talk about varieties here. Statistics show that
bites rarely result in death. There are 7000-8000 venomous bites each year
in the US, resulting in 5-15 deaths (.07 - .21%).

85% of venomous snakebites are below the knee.

Fewer than 50% of snakebites actually contain venom, evidently venomous
snakes have a strategy of conservation. They might also have poor timing.
The bite and the injection of venom are two carefully coordinated actions.
Also some bites are single-fang. Examining the bite area will help in
deciding strategy. A single fang bite, not deep, is not of much concern
compared with a double, bit deeply. Sometimes the venom is squirted before
the bite <lots of joke potential>.

The venom of an immature snake can be more concentrated that an adult
snake. (this surprised me)

Every state on the AT has rattlesnakes & copperheads except for Maine.
Personally I?ve seen rattlesnakes as far North as Harriman SP in New York.
I?ve seen one copperhead in NH, although it was many miles away from the
AT.

Rattlesnake venom can affect the brain and spinal cord.

Copperhead venom is milder, less dangerous, and sometimes does not require
antivenin treatment. Monitoring is done instead.(This should be weighed
against the likelihood of bite. Copperheads are considered aggressive,
rattlesnakes need to be provoked)

Treatment in the Field:
Immobilize the limb to avoid pumping the venom around your body. Use a
slighting constricting bandage but do not restrict vascular flow. The
bandage goes between the bite area and the heart, try to get it 2-4 inches
above the bite. Keep the bit area at the same level (or a bit below) the
heart. This means lying down if the bite is on your leg


Presence of venom will cause intense burning pain and swelling around the
holes. Low blood pressure, rapid heart rate, tingling of lips and tongue
might also occur. Metallic taste in mouth, nausea, diarrhea, and more are
reported.

Do not cool the bite area. One reference states ?do not pack the wound
site in large amounts of ice?. Evidently using ice will increase damage
rather than diminish it, increasing chances of limb amputation. I still
wonder if cool/cold water will worsen the situation. I?m sure the cool
water will lessen the pain and perhaps some swelling!

No incisions, they are proved to be not useful. Doctors say there is no
known benefit, the downside is a treatable infection so go ahead and cut
if it makes you feel better.

Forget about the vacuum pump also. (good news for ultra light hikers). One
source says that you might remove 30% of injected venom if used within 15
mins. (no incision), another source states that it removes a lot of blood
but less than 2% of the injected venom. The disagreement is between
manufacturer?s claims and an independent study. The Sawyer Extractor pump
was particularly mentioned as ineffective in this months Annals of
Emergency Medicine (Feb. 2004).

Treatments at the hospital:
Antivenin (anti-venom) is given typically. The dosage has side-effects
that can last for several days. Many doctors prescribing antivenin in the
ER will assume a ?worst-case? bite and gauge the dose accordingly,
factoring in body weight. (Doctors on this list have provided some good
info in the past about this. Any comments?) Some feel this aggressive
treatment is harder on patients than letting a low-grade bite run it?s
course. One side-effect of this treatment is anaphylactic shock for those
allergic to horse or sheep proteins (used to create the antivenin). CroFab
(Crotaline Fab) is a new antivenin that uses modified sheep protein, one
digested with an enzyme to reduce allergic reaction. The enzyme treatment
also allows the antivenin to be cleared from the body more rapidly.
Horse-derived antivenin will likely cause a lifelong sensitivity to horse
products. This can make a second bite a very risky proposition if treated
again with the same antivenin.

Fasciotomy ? surgical removal of tissue around the bite. Done by a doctor
in order to diminish severe compartment pressure.

Venomous bites cause tissue necrosis which causes significant scarring. 
Skin grafts are required to repair the damaged area.

I?m not a doctor, nor do I play one when I?m on the Appalachian Trail.
--RockDancer