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C. Gila Monsters: These lizards are not large, seldom reaching 20 inches in length. They
have blunt heads, beady eyes, and powerful digging claws on short legs. They are shy and
appear sluggish, but are capable of swift, determined lunges when threatened or handled.
II. PREVENTION
Wilderness travelers are rarely bitten by venomous reptiles. Avoid reptile bites by: 1)
staying away from infested areas; 2) not hiking during times of peak reptile activity
(usually at night); 3) watching clearly where one steps; 4) never reaching into concealed
areas (gathering firewood at night for example); 5) checking bedding, clothing, and
footwear before use; 6) and never handling a venomous reptile, even if it is presumed
dead (reflex allows some snakes to strike even after death). The chance of envenomation
from a strike can be minimized by wearing high leather boots and long pants.
Envenomation is more apt to occur in persons who are intoxicated and in young children.
It is helpful to know the distribution, markings, and characteristics of venomous reptiles
in intended areas of wilderness travel.
III. GUIDELINES FOR ASSESSMENT AND TREATMENT
A. Pit Vipers: As many as 20 to 30% of crotalid bites cause no envenomation. Most, but
not all, crotalid envenomations result in immediate pain at the bite site, and a rapid onset
(within 10 to 15 minutes) of swelling and ecchymosis. Rarely, signs of envenomation are
delayed for several hours. Typical paired fang wounds are not always present. A single
puncture or a scratch may be the only mark, and the degree of envenomation does not
correlate with the size, quality, and number of fang marks.
Assessment of envenomation by a pit viper is the first step in managing a bite in
the field. Mark the advancing border of edema and sequentially measure and mark the
circumference at the site and at least one location above the bite to detect spreading
edema. Reassess these measurements every 15 minutes. Gently cleanse the area. Apply a
sterile or clean dressing. The basic tenet is to provide calm, rapid transport to a medical
facility. For an extremity bite, splint the limb. Do not use pressure dressings, tourniquets,
applications of cold, electric shocks, or incisions of the bite site, as these techniques have
no known efficacy. Lymphatic constricting bands (barely indenting the skin) are
advocated by some, although their use has not been proven to have any definite
advantage in pit viper envenomations.
Encourage the patient to rest and stay calm. Keep the extremity at heart level or
lower. Walking out should not be attempted unless no other evacuation means is
available. Walking out, however, is imperative if the patient is alone. Severe
manifestations of poisoning may not occur for several hours, so travel is possible in most
cases.
For those with the skill and equipment, use of oxygen is recommended, as is one
large-bore (16 g or larger) IV in an unaffected limb. Start at least two large-bore IVs in a
patient presenting with shock. Administer either normal saline or Ringer's lactate solution
(LR) to support systolic blood pressure above 90 mm Hg. Intubation or vasopressors are
rarely necessary in crotalid envenomations. Field use of intravenous antivenin is not
recommended.
