IMMEDIATE FIRST AID
for bites by
Bothrops species of Central & South America
In the event of an actual or probable bite from a Bothrops, 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 bites.
- 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 20 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
Bothrops species of Central & South America
The bite of Bothrops species can be fatal. In Central and South America it is
responsible for the majority of snakebite fatalities. The snake is often
aggressive and some species can be arboreal. Victims will usually complain of
pain at the bite site and swelling may be evident. Tremendous local tissue
destruction can ensue, along with a substantial coagulopathy. Prompt medical
therapy avoids these problems. Please read the attached and respond
- First Aid:
- Apply constricting band if not already present, proximal to bite on
arms, legs, hands, or feet. Apply suction with the Sawyer Pump extractor for
10-20 minutes. Rest the extremity below the patient's heart.
- Transport to a medical center emergency or trauma service.
- 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 data.
- Wait 20 minutes.
- Reconstitute 5 vials of Wyeth Crotalidae Polyvalent antivenom in 50 cc
Lactated Ringers (10 ml/vial).
- If no reaction to intradermal skin test, administer antivenom by
intravenous infusion 1 vial (10 cc) every 5-10 minutes. The constricting band
can be removed after the first vial has been infused. One should anticipate
using 5-10 vials for minor to moderate bites, and 10-40 vials for moderate to
- Monitor signs, symptoms, and laboratory data and administer additional
aliquots of 5 vials of antivenom as needed to neutralize signs and symptoms at
a rate of 1 vial (10 cc) every 5-10 minutes.
- If patient is allergic to horse serum, administer 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 titrated.
for bites by
Bothrops species of Central & South America
This person has received a bite and probable envenomation from a Bothrops
species. These snakes are very aggressive and one of the most venomous in
Central and South America. They account for the majority of snakebite related
fatalities on these continents. Envenomation presents predominately with edema,
pain, and hematologic manifestations. Dizziness, headaches, and necrosis can
also be present. In some less common species (such as B. jararacussu of
Brazil), blindness may present early after a bite. In severe envenomations,
peripheral circulatory collapse, acute renal failure, and cerebral hemorrhage
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 absorption. 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 present with the patient. This antivenom contains the necessary
fractions to neutralize the venoms of all Central and South American species of
- If the patient has been envenomated, the initial treatment is 5 to 40
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:
- These signs and symptoms will usually manifest earliest, though their
development will vary considerably from case to case. Not all of these will
necessarily occur, even with severe envenomation.
Edema & Pain
|Hemorrhage (gingival, nasal, wound, rectal)
|Tingling of extremities
- General: The above symptoms can manifest within 5 hours after
envenomation. Edema usually begins within the first few minutes after the
- Local Symptoms: Though pain and edema are the major local manifestations,
hemorrhage around the bite site is common. Tissue necrosis is seen less
frequently. Extensive necrosis can occur. Other local signs include:
- Local blister formation
- Local and scattered skin discoloration
- Hematology: Bothrops venom has been shown to consume prothrombin,
fibrinogen, and clotting factors II, V, VIII, IX, X, and XI. This results in a
DIC type coagulopathy with an increase in PTT and bleeding times. Fibrinogen
levels and sedimentation rates are generally decreased. However, platelets are
within normal limits. Microembolism to the lung and other organs is seen along
with a greater than 50% occurrence of leucocytosis (10,000-50,000).
- Urinary Symptoms:
||8% - 25%
|Hyaline and granular casts
- 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). The presence of fang marks does not always imply
that envenomation occurred. Multiple bites inflicted by a single snake are
also possible, and should be noted if present. WATCH THE PATIENT CLOSELY.
- Severe Envenomation: One or more of the following clinical pictures can
- Hypotension and increased heart rate secondary to peripheral circulatory
- Acute Renal Failure secondary to diffuse glomerulonephritis.
- Cerebral hemorrhage and edema secondary to DIC.
- 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:
- Prothrombin 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
- Free Protein
- Electrocardiogram. Place patient on continuous cardiac monitoring.
- A brisk urine output measurement should be obtained. 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 occurred.
- 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 injected).
- 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 those 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 minor or moderate signs of envenomation, or
has a prior history of anaphylactic or anaphylactoid response to antivenom,
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
- 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. Gently 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
- Assuming that the patient is tolerating the infusion well, additional
antivenom may be given at a rate of one vial/5-10 minutes. The first 5 vials
should be given over the first hour of treatment.
- 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.
- Cardiovascular symptoms are usually seen only in severe envenomations.
They usually present as hypotension and increased heart rate. Patients should
be treated for peripheral circulatory collapse by continuing peripheral I.V.
infusion of Lactated Ringers about 250 cc/hr and administering vasopressors and
- Acute Renal Failure is seen in severe envenomations. It may necessitate
- If significant limb swelling occurs, orthopaedic evaluation with
intracompartment and subcutaneous tissue pressure measurements can be obtained.
Surgical debridement or fasciotomy is very rarely if ever indicated.
- Hematologic symptoms may present as a Disseminated Intravascular
Coagulopathy, and are treated as other DICs.
- 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 1 to 10 in
Lactated Ringers, transfer the solution to an IV piggyback setup, and deliver
over a period of 7-10 minutes per vial. One should anticipate using 5-10 vials
for minor to moderate bites, and up to 40 vials for severe bites.
- 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 variablility: 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.
- Fluid management is very important in snakebite cases. The patient
should be well hydrated and a brisk urine output maintained.
- Morphine is CONTRAINDICATED because of its tendency to suppress respiration.
Alcohol should also be avoided.
- In cases which Circulatory Shock remains uncorrected by antivenom
therapy, plasma volume expanders and/or vasopressor agents may be given with
- If the patient remains oligoanuric, dialysis should be considered early.
- Tetanus prophylaxis should be current
- Antibiotics are NOT recommended prophylactically.
- Local Necrosis: Prompt delivery of antivenom following the bite may lessen
the extent of local tissue damage, although some evidence suggests that certain
antivenoms have less efficacy in ameliorating or protecting against the local
action of Bothrops venom. This latter statement should not be held as a
contraindication to the use of antivenom in those Bothrops bites in which local
- Multiple Bites: It is possible for Bothrops to deliver more than one bite
in a single attack and thus may inject a large volume of venom. If there is
evidence that such an attack occurred (i.e. history or multiple bite sites),
twice the initial dose of antivenom should be given (i.e. 10 vials over 70-100
minutes at the rate of one vial per 7-10 minutes). Always watch closely for
signs of allergic response; if they occur, treat appropriately and with slow
infusion rate. Give all subsequent doses in 5 vial increments at a rate of 1
vial per 7-10 minutes as necessitated by the presence of continued signs and
- Severe Envenomations: If the patient shows severe signs of envenomation,
particularly if early after the bite, treat as a multiple bite, administering
10 vials of antivenom over the first 70-100 minutes. Give all subsequent doses
in 5 vial increments at a rate of 1 vial/7-10 minutes as necessitated by the
presence of continued signs and symptoms.
- If the patient is otherwise stable, but has elevated blood levels of urea
and serum creatinine and/or has persistent oliguria or anuria, long term
follow-up on kidney function should be instituted to rule out renal cortical
The following references are recommended for further indepth reading. This
material includes case histories, guidelines, and recent findings in South
American literature. These should be read only after treatment has begun and
the patient is in stable status.
- Wyeth Crotalidae Polyvalent Antivenom: Wyeth Laboratories. Lyophilized
polyvalent Anti-snake venom: Directions of Use (Package insert with
Antivenom). January 1984.
- Silva, J.: Accidentes Humanos por Las Serpientes de los Generos Bothrops y
Lachesis. Mem. Inst. Butantan. 44/45:403-423, 1980/81.
- Ayerbe, S., Paredos, A., Galves, D.A.: Estudio Retrospectivo Sobre
Ofidiotoxicosis en el Departamento del Cauca. Caud Med. Pop. (Columbia) 40-2:
- Ayerbe, S., Otero, L.M., Galves, D., Paredes, A., Vasquez, A.: Estudio
Retrospectivo Sobre Ofidiotoxicosis en el Departamento del Cauca. Cuadernos de
Medicina Popayan (Columbia) 2(3), November 1977.
- Barrantes, A., Solis, V., Bolanos, R.: Alteracion de los Mechanisimos de la
Coagulacion en el Envenenamiento por Bothrops asper (Terciopelo). Toxicon 23.
No. 3, 399-407, 1985.
- Marinkelle, C.J.: Accidents by Venemous Animals in Columbia. Industrial
Medicine and Surgery. 35:11, 988-992, 1966.
- Morre, G.M., Dewling, H., Minton, S.A., Russell, F.E.: Poisonous Snakes of
the World. U.S. Government Printing Office, Washington, D.C., 1968.
- Russell, F.E.: Snake Venom Poisoning. Scholium International, Inc. Great
Neck, New York, 1983.
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