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-Reader Submitted Article
Snakebites in the Field
In Europe and North America more people die from bee and wasp stings
than snake bites. Yet a snake bite in a survival situation is a
nasty thing to contemplate. A bite can be life threatening; and
unfortunately, only hospital care can improve the chances for survival
of the person and to reduce the aftereffects of a bite. However
failure to take preventive measures or failure to treat snakebite
properly in a survival situation can result in needless illness.
Deaths from snakebites are rare. Although all bites by poisonous
snakes must be considered medical emergencies until it is proven
that envenomation has not occurred, many such bites will prove not
to be life threatening because the snake did not inject venom. No
envenomation occurs in approximately 20% of documented bites by
New-World pit vipers - rattlesnake, copperhead, water moccasin,
and fer-de-lance. An even higher percentage of bites inflicted by
other snake families (e.g., up to 50% for cobras and 75% for sea
snakes) are "dry."
The most common complication of pit viper snakebites is called
Compartment Syndrome (in which increased pressure caused by inflammation
and tissue swelling within a confined space in the body impairs
blood supply, leading to nerve damage and muscle death). This can
be a direct result of the snakebite or also from misapplication
of a constriction band. Snakebite can also lead to:
- Local wound complications that may include infection and skin
loss.
- Cardiovascular complications, blood disorders, and pulmonary
collapse may occur.
- Prolonged neuromuscular blockade may occur from coral snake
envenomations.
Most viper bites contain hemotoxic elements which damage tissue
and affect the circulatory system by destroying skin tissues and
causing internal hemorrhaging. Viper venom also contains neurotoxic
components which immobilize the nervous system, affecting the victim's
breathing, sometimes stopping it. Most vipers have venom composed
primarily of hemotoxic properties. Baby rattlesnakes and the Mojave
Rattler are an exception; they have venom which contains more neurotoxic
properties than hemotoxic -- which makes them very dangerous. The
Sea Snake, Coral Snake, and Cobra family of snakes also have venom
with dominant neurotoxic characteristics but they too have hemorrhagic
toxins. The venoms also contain digestive enzymes (cytotoxins) to
aid in digesting their prey. When you have been bitten, the venom
also begins to digest you from within (Happy thought). These venoms
can cause a very large area of tissue death, leaving a large open
wound. This condition could lead to the need for eventual amputation
if not treated.
Signs & Symptoms
A snakebite, whether from a venomous or non-venomous snake, usually
causes terror, with nausea, vomiting, rapid heartbeat, diarrhea,
profuse sweating, which may be difficult to distinguish from signs
of true envenomation.
Shock and panic in a person bitten by a snake can also affect the
person's recovery. Excitement, hysteria, and panic can speed up
the circulation, causing the body to absorb the toxin quickly. Signs
of shock may occur within the first 30 minutes after the bite.
Pit vipers, such as rattlesnakes, cotton mouth (water moccasins),
copperheads, Fer-de-lance and bushmasters are the most common venomous
snakebites in the Americas. Many pit viper bites are dry (venom
is not deposited), and no systemic symptoms or signs develop.
Some of the signs of envenomation may include:
- Bleeding from the site.
- Fang mark(s) and scratch(es).
- If envenomation has occurred, swelling and redness of skin or
bruising at the bite site and adjacent tissues will occur, usually
within 30 to 60 min.
- Pain, tingling or burning at the area of the bite.
- Some rattlesnake bite victims develop a rubbery, minty, or metallic
taste in their mouth.
- The venom of most North American pit vipers produces minor neuromuscular
conduction changes, including generalized weakness and a sensation
of tingling, pricking, or numbness of the person's skin.
- Blurred vision, weakness, dizziness and fainting, nausea, difficulty
breathing.
- Swelling progresses rapidly and may involve the entire extremity
within hours.
- Enlarged, tender regional lymph nodes may develop.
- Temperature increases over the bite area.
- In moderate or severe envenomations, bruising & discoloration
is common and may appear at and around the bite site within 3
to 6 hours.
- Bruising & discoloration is most severe after bites by Eastern
and Western diamondbacks; cottonmouths; and prairie, Pacific,
and timber rattlesnakes.
- Bruising& discoloration is less common after copperhead
and Mojave rattlesnake bites.
- The skin around the bite may appear tense and discolored.
- Blisters, of watery liquid or blood or both, usually appear
at the bite site within 8 hours.
- Necrosis around the bite site is common after rattlesnake envenomations.
- Most venom effects on soft tissues peak within 2 to 4 days.
NOTE: Neurotoxins such as the Mojave rattlesnake, coral
snakes, etc are a particularly dangerous for its ability to inflict
severe, even fatal, injury without any appreciable degrees of pain
or swelling; patients bitten often do not exhibit these signs and
symptoms because its venom is more neurotoxic than that of the average
pit viper. The absence of local symptoms and signs may erroneously
suggest a dry bite, producing a false sense of security for the
victim. Weakness of the bitten extremity may not become evident
for 12 hours or more. Systemic neuromuscular disorders may be delayed
for 12 hours and include weakness and lethargy; altered mental state,
including euphoria and drowsiness, blurred vision, slurred speech,
and difficulty swallowing; increased salivation; and respiratory
distress or failure. Once the neurotoxic venom effects manifest,
they are difficult to reverse and may last 3 to 6 days. Untreated
patients may die of respiratory failure.
Care
The only proven therapy for snakebites is antivenom! Antivenom
neutralizes the venom and has to be started within hours of the
bite. Unless you have a portable emergency room with lab support,
and a doctor along, forget about carrying the IV solutions, 10-20
vials of antivenom for vipers or the 10 possibly needed neurotoxin
snakes. The person needs critical care and promptly!
The phrase "first, do no harm" has significant meaning
here because many poor attempts at first-aid may do more harm than
good; including things like making an incision over the bite, mouth
suctioning, tourniquets, ice packs, or electric shock. A primary
concern in the treatment of snakebite is to limit the amount of
eventual tissue destruction around the bite area.
If you determine that a poisonous snake did bite an individual,
take the following steps:
- "In the field, the victim should move or be moved beyond
the snake's striking distance. Many snakes will not travel more
than 20 feet after biting a person.
- The victim should avoid exertion and be reassured, kept warm
and rapidly transported to the nearest medical facility.
- A bitten extremity should be loosely immobilized in a functional
position just below heart level.
- All rings, watches, and constrictive clothing should be removed.
- Some providers strongly advocate the use of pressure-immobilization
techniques only for snakebites caused by neurotoxic-predominant
species. However, other providers advocate pressure-immobilization
for all venomous snakebites; however, pressure immobilization
may cause arterial insufficiency and necrosis if applied improperly.
- If it can be placed within 30 minutes, a pressure wrap (e.g.
Ace Bandage) is placed above the bite about 2-4 inches. The wrap
should be just tight enough to impede lymphatic flow, thereby
delaying the systemic absorption and circulation of the venom
but not so tight to restrict venous or arterial circulation; snug
as if applying a bandage for a sprain, yet able to slide a finger
under the bandage. As swelling progresses, the bandage may need
to be reapplied to prevent compressing the tissues.
- Set up for shock and force fluids or give by intravenous (IV)
means.
- Maintain an airway (especially if bitten near the face or neck)
and be prepared to administer mouth-to-mouth resuscitation or
CPR.
- Wash the bite with clean water and soap or antiseptic swabs.
While washing look for embedded fangs or teeth in the wounds.
- Immobilize the bitten area and keep it lower than the heart.
- If hospitalization will be more than 30 minutes, a suction device
(The Extractor from Sawyer Products) may be placed over the bite
to help draw venom out of the wound without making cuts.
- In the USA, identifying the snake is not a concern as it once
was, due to the new antivenom is now designed for all pit vipers
in the country. Trying to kill a snake is dangerous. A rattlesnake
can strike and bite for more than an hour after its death.
NOTE: Snake toxin is not inactivated by changes in temperature
or pH. Application of ice, hot packs, or vinegar only wastes time.
All other out-of-hospital interventions (e.g., tourniquets, topical
preparations, suction by mouth or with a device with incision, cryotherapy,
and electrical shock) are of no proven benefit, may be harmful,
and may delay appropriate treatment.
DO NOT
- Do not cut the bite. Cutting opens capillaries that in turn
open a direct route into the blood stream for venom and infection.
- Do not apply a tourniquet. Such action can result in the loss
of the limb.
- Do not try to suck out the venom by mouth. You can try the suction
cup in a snakebite kit if it doesn't delay other needed treatment.
Suctioning seldom provides any measurable advantages, however.
- Do not apply cold and/or ice packs. Recent studies indicate
that application of cold or ice makes the injury much worse.
- Do not give the victim stimulants, alcoholic beverages or tobacco
products.
- Do not give blood thinners such as aspirin or acetaminophen.
- Do not put your hands on your face or rub your eyes, as venom
may be on your hands. Venom may cause blindness.
- Do not break open the large blisters that form around the bite
site.
Follow-up Care
A snakebite wound can become infected from bacteria in its mouth.
With nonpoisonous as well as poisonous snakebites, this local infection
is responsible for a much of the damage that can result later.
- If infection appears, keep the wound open and clean.
- Use heat after 24 to 48 hours to help prevent the spread of
local infection. Heat also helps to draw out an infection.
- Keep the wound covered with a dry, sterile dressing.
- Have the victim drink large amounts of fluids until the infection
is gone.
-Jerry B Blaine
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