IMMEDIATE FIRST AID
for bites by
United States & Canadian Rattlesnakes
In the event of an actual or probable bite from a U.S. or Canadian
rattlesnake, execute the following first aid measures without delay.
- Make sure that the responsible snake or snakes have been appropriately
and safely contained, and are out of danger of inflicting any additional
- Immediately call for transportation.
DO NOT cut or incise the bite site.
- Keep the victim calm and reassured. Allow him or her to lie flat and
avoid as much movement as possible. If possible, allow the bitten limb to rest
at a level lower than the victim's heart.
- Identify the bite site, looking for fang marks, and apply the Sawyer
Pump extractor with the largest cup possible over the bite site. If there are
two or more fang marks noted on the limb, apply the pump extractor over at
least one fang mark. If more than one pump extractor is available, they may be
applied to the additional fang marks.
- Immediately wrap a large constricting band snugly about the bitten limb
at a level just above the bite site, ie. between the bite site and the heart.
The constricting band should be as tight as one might bind a sprained ankle,
but not so tight as to constrict blood flow.
- DO NOT remove the constricting band until the victim has reached the
hospital and is receiving Antivenom.
- Have the Wyeth Crotalidae Polyvalent Antivenom ready for the emergency
crew to take with the victim to the hospital. Give them the following:
- the available antivenom (at least 10 vials)
- the accompanying instruction (Protocol) packet
- the victim's medical packet (if available)
DO NOT apply ice to the bite site.
Summary for Human Bite
United States & Canadian Rattlesnakes
The bite of rattlesnakes is rarely fatal. Victims will usually complain of
pain at the bite site and swelling may be evident. Tremendous local tissue
destruction can ensue. Prompt medical therapy avoids this problem. Please
read the attached and respond appropriately.
- First Aid:
- Apply constricting band if not already present, proximal to bite on
arms, legs, hands, or feet.
- Transport to a medical center emergency or trauma
- Medical Management:
- Call your local Poison Control Center, or the San Diego Regional
Poison Control Center (800 876-4766). They should locate a consultant to help
you treat this patient.
- Observe for Signs and Symptoms of Envenomation.
- If signs or symptoms are present, perform the following:
- Apply intradermal skin test.
- Administer Lactated Ringers intravenously at a
rate of 200 cc/hour. Obtain appropriate blood and urine laboratory
- Wait 20 minutes.
- Reconstitute 5 vials of antivenom in 50 cc Lactated Ringers.
- If no reaction to intradermal skin test, administer antivenom by
intravenous infusion 1 vial (10 cc) every 5-10 minutes. The constriction band
can be removed after the first vial has been infused.
- Monitor signs, symptoms, and laboratory data and
administer additional aliquots of 5 vials of antivenom as needed to
neutralize signs and symptoms. Average treatment is 15 vials (range 0-40
- If patient is allergic to horse serum, administer 1 gram Solu-Medrol
IV push, wait 30-45 minutes, and then begin intravenous antivenom. Be prepared
to administer Benadryl and epinephrine.
- In case of intravenous envenomation, administer
antivenom IV push, 1 vial every 1 minute, until symptoms improve, then
continue by intravenous infusion until signs and symptoms are
for bites by
United States & Canadian Rattlesnakes
This person has received a bite and probable envenomation from a
rattlesnake. There are several species of rattlesnakes within the United
States and Canada, envenomation by all of which will be covered by this
protocol. Those snakes which are indigenous to Mexico, Central America, and
South America, whose ranges do not overlap into the United States, will be
covered in separate protocols. Fatalities in modern times are infrequent. The
venom can produce a wide spectrum of clinical manifestations, including local
tissue destruction, cardiovascular collapse, coagulopathy, and with some
species neurotoxic and neuromuscular symptoms.
Please read and execute the following procedures without delay.
- A constricting band should be in place proximal to the bite site. If
present leave in place, if not apply a penrose drain as if for venipuncture.
This retards venom absorbtion. DO NOT remove until the patient has
arrived at the hospital and is receiving the antivenom.
- Make sure that at least 20 vials of Crotalidae Polyvalent Antivenom
(Wyeth) are available. This antivenom contains the necessary fractions to
neutralize the venoms of all United States and Canadian rattlesnakes.
- If the patient has been envenomated, the initial treatment is 5 to 10
vials of intravenous antivenom. Envenomation is diagnosed by the presence of
characteristic signs and symptoms. Necessary information follows and is
organized in sections:
- Signs and Symptoms of Envenomation
- Medical Management
- General Considerations
- Special Considerations
Signs and Symptoms of Envenomation:
The specific signs and symptoms which may manifest in a patient who has
been envenomated will vary in presence and in severity, depending on several
factors noted in the General Considerations below. The time course of
development will also vary considerably from case to case. The following list
of signs and symptoms represent a general compilation enumerated from a series
of 100 cases of rattlesnake envenomation (Russell, 1983). Not all of the
symptoms will necessarily develop, even with severe envenomation.
|Sign or Symptom
|Sweating and or Chills
|Numbness, tingling |
(circumoral, lingual, scalp, feet, etc.)
|Pulse rate changes
|Nausea and/or vomiting
|Blood pressure changes
|Numbness, tingling in the affected part
|Decreased blood platelets
|Vesicles or boli
|Regional lymph adenopathy
|Respiratory rate changes
|Increased blood clotting time
|Change in body temperature
|Local tissue necrosis
|Spearing of red cells
|Hematemesis, hematuria, melena
|Blurring of vision
|Increased blood platelets
Fang Marks: Fang marks may be present as one or more well defined
punctures, as a series of small lacerations or scratches, or there may not be
any noticeable or obvious markings where the bite occurred. The absence of
fang marks does not preclude the possibility of a bite (especially if a
juvenile snake is involved). However with rattlesnake envenomation, fang marks
are invariably present and are generally seen on close examination. Bleeding
may persist from the fang wounds. The presence of fang marks does not always
indicate envenomation; rattlesnakes when striking in defense will frequently
elect not to inject venom with the bite, resulting in a dry bite (i.e. no
envenomation). Manifestations of signs and symptoms of envenomation is
necessary to confirm the diagnosis of snake venom poisoning.
- Admit patient to an emergency or trauma service and call the consultant
identified by the Poison Control Center.
- Begin a peripheral intravenous infusion (18 gauge catheter) of Lactated
Ringers Solution at the rate of 250 cc/hr.
- Draw blood from the contralateral arm, and collect urine for the
following laboratory tests. Mark STAT.
- Type and Cross Match TWO units of whole blood.
- CBC with differential and platelets.
- Coagulation Parameters:
- Prothombin Time (PT)
- Partial Thromboplastin Time (PTT)
- Fibrinogen levels
- Fibrin Degradation Products
- Serum Electrolytes, BUN/Creatinine, Calcium, Phosphorus.
- Lactate Dehydrogenase (with Isoenzyme analysis). Isoenzyme analysis
may indicate multiple targets of venom components which may dictate further
- Urinalysis (Macroscopic and Microscopic Analysis).
Must include analysis for:
- Free Protein
- Electrocardiogram (Sinus Tachycardia would be expected).
- Intermittent or indwelling Foley Catheter to monitor
urine output may be necessary in the conscious, impaired patient.
- Additional tests as needed or indicated by the patient's hospital
- It may be necessary or practical to repeat some of the above serum
and urine tests periodically over the hospital course to monitor the effects of
antivenom therapy or to detect late changes in laboratory values.
- OBSERVE PATIENT CLOSELY for signs and symptoms of envenomation, which
usually manifest between 15 minutes and two hours after the bite
- If NONE of the signs or symptoms have been noted after two hours,
there is a possibility that the patient received a dry bite (no venom
- Remove the constricting band, watching carefully for any changes in the
patient's status. If any changes occur, assume the patient has been envenomed,
and prepare to give antivenom immediately (as directed below).
- If signs and symptoms still fail to manifest, continue CLOSE
observation of the patient for an additional 12 to 24 hours.
- IF ANY SIGN OR SYMPTOM becomes apparent or has been noted during the
course of treatment, begin Antivenom Therapy as follows:
- Patients manifesting severe symptoms or who are suspected of having
an intravenous injection of venom, should be treated immediately with antivenom
and should not undergo skin testing. Corticosteroid adjuncts may facilitate
the delivery of rapid infusion. One should use the dilutions below, but infuse
at a rate of 1 vial (10 cc) per minute.
- If the patient is exhibiting envenomation, inject
intracutaneously the skin test sample included in the antivenom package,
sufficient to raise a small weal.
- The skin test should be read after 15 minutes, but it
is wise to check the test area and observe the patient constantly during
the period following the injection. If there is no evidence of erythema or
vesicular response, the test should be considered negative.
- A positive test IS NOT a contraindication to giving
antivenom, but should alert the clinician that the rate at which the
antivenom is delivered and/or the use of corticosteroids may need to be
adjusted to control potential untoward responses.
- Assuming that the above skin testing precautions have
been done, reconstitute the contents of 5 vials of Wyeth Crotalidae
Polyvalent Antivenom in Lactated Ringers Solution. Vigorously shake the vials
to assure that the contents are thoroughly mixed, and that there is a minimum
of undissolved particles. Transfer the dissolved solution via a syringe to an
IV piggyback setup with a volumetric regulator. Make sure that there are no
undissolved particles in the solution transfer.
- Administer the diluted antivenom intravenously over a
period of 10 minutes for the first vial (1 cc/minute).
- Should any signs of ALLERGY/ANAPHYLAXIS (e.g. coughing, dyspnea,
urticaria, itching, increased oral secretions, etc.) develop, immediately
discontinue the administration of antivenom and treat symptoms with
Corticosteroids, Epinephrine, Benadryl, Atarax, and/or other Antihistamines as
necessary. As soon as the patient is stabilized, continue the antivenom
infusion at a slower rate.
- After 10 minutes of antivenom administration, the
constricting band may be removed.
- Assuming that the patient is tolerating the infusion
well, additional antivenom may be given at a rate of 1 vial every 5-10
minutes. The first 5 vials should be given over the first hour of
- Antivenom Therapy is the mainstay of treatment for rattlesnake
envenomation. Many of the symptoms are ameliorated or entirely eliminated by
the antivenom alone. Other symptoms will require additional modalities of
therapy to correct.
- Hematologic symptoms may present as Disseminated Intravascular
Coagulopathy, and are treated essentially as other DICs.
- Neurological symptoms: If the patient is suspected of having been
bitten by the Mojave rattlesnake (Crotalus scutulatus), the patient may develop
neurological symptoms including respiratory obstruction or failure which must
be treated as an immediate emergency. The neurologic symptoms, as others,
should be improved by antivenom. If breathing becomes impaired, respiratory
assistance may be necessary, and intubation and ventilation may be appropriate
adjuncts in certain clinical settings. Secretions may become copious,
- It is important to keep venom neutralization current and continuous.
The best method to accomplish this is to keep a close watch on the patient's
status. If the present condition does not improve, or should it worsen for any
reason, additional antivenom should be administered. Give all additional
antivenom in 5 vial increments. Again, dilute the antivenom thoroughly in
Lactated Ringers, transfer the solution to an IV piggyback setup, and deliver
over a period of 5-10 minutes per vial. Most bites today are treated with 15
to 20 vials of antivenom. The range is 5 to 40 vials.
- It is advisable to check periodic serum and urine analyses during
therapy as outlined above.
- It is always best to keep the patient in an Intensive Care setting
until free of major symptoms for 24 hours. The patient should be observed in
the hospital for at least 24 hours after the major symptoms abate.
- It is important that the patient be placed at rest, kept warm, and avoid
- Symptom variability: As noted above, the variability of symptoms in
rattlesnake envenomation can be great. It is important to note the continual
progression of symptoms throughout the course of therapy, and give additional
antivenom as necessary to titrate these symptoms.
- Neurotoxic symptoms: In the United States one species of rattlesnake,
the Mojave Rattlesnake (Crotalus scutalatus), is known to produce a clinical
picture with predominantly neurotoxic symptoms. The onset and progression of
the symptoms may be rapid and subtle. In addition, they are more rapidly
reversed in their early stages than when fully developed. It may be necessary
to wake the patient and perform a brief neurologic check every hour or so to
assure that breathing and other vital functions are not impaired. Carefully
note the progression of respiratory paralysis which may be present. Be
prepared to intubate and ventilate as necessary.
Other rattlesnake species in the United States may have neurotoxic
components in their venom. However generally speaking, these are at low levels
and do not usually manifest significant clinical symptoms.
- Compartment Syndrome: It should be noted that fascial compartment
syndrome in rattlesnake envenomations is very rare. Limbs may swell
significantly, but rarely involve specific fascially bound compartments. If
however the logistics of the bite raise a high index of suspicion for
Compartment Syndrome, monitoring with a Wick Catheter or appropriate pressure
devices may be necessary. Fasciotomy is rarely if ever recommended in these
The following references are recommended for further indepth reading. This
material includes case histories, guidelines, and recent findings in crotalus
literature. These should be read only after treatment has begun, and the
patient is in stable status.
- Russell, F.E.: Snake Venom Poisoning. Scholium International, Inc.
Great Neck, New York, 1983.
- Parrish, H.M.: Incidence of treated snakebite in the United States.
Public Health Rep. 81: 269-276, 1966.
- Russell, F.E., Cawlson, R.W., Wainschel, J., Osborne, A.H.: Snake venom
poisoning in the United States. JAMA 233: 341-344, 1975.
- Schmidt, K.P. and Inger, R.F.: Living Reptiles of the World. New
York: Doubleday & Company 1957.
- Gans, C., Bellairs, A. and Parsons, T. (Eds.): Biology of the Reptilia,
Volume 1. London: Academic Press. 1969
- Phelps, T.: Poisonous Snakes. Poole, Dorset: Blandford Press.
- Klauber, L.M.: Rattlesnakes, Volume I. Berkeley: University of
California Press. 1972
- Klauber, L.M.: Rattlesnakes, Volume II. Berkeley: University of
California Press. 1972
- Klauber, L.M.: Rattlesnakes. Berkeley: University of California Press.
- Minton, S.A., and Minton, M.R.: Venemous Reptiles. New York:
Scribner's Sons. 1969
- Bronstein, A.C., Russell, F.E., Sullivan, J.B.: Negative pressure
suction in the field treatment of rattlesnake bite victims.
- Davidson, T.M.: Intravenous Rattlesnake Envenomation. West J Med,
148: 45-47, 1988.
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