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| ==Crotaline (Pit Vipers)== | | ==Overview== |
| ===Background===
| | In the United States, snake bites can be organized into [[Crotaline (Pit Vipers)]] and [[Elapidae (Coral Snakes)]]. Although somewhat simplified, the Crotalidae family also includes rattlesnakes, Sistrurus and Agkistrodon species (water moccasins and copperheads).<ref>Goldfranks Toxicology - Envenomations</ref> |
| *Includes rattlesnakes and copperheads
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| *Venom causes local tissue injury, hemolysis, coagulopathy, neuromuscular dysfunction
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| *Up to 25% of bites are dry bites
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| ===Clinical Features=== | | ==See Also== |
| #Fang marks, localized pain, progressive edema extending from bite site
| | *[[Crotaline (Pit Vipers)]] |
| ##Edema near the airway or in muscle compartment may threaten life or limb
| | *[[Elapidae (Coral Snakes)]] |
| #Nausea/vomiting, oral numbness/tingling, dizziness, muscle fasciculations
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| #Ecchymoses may appear within minutes to hours
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| ===Diagnosis===
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| #Must have a snakebite + evidence of tissue injury:
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| ##Local injury (swelling, pain, ecchymosis)
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| ##Hematologic abnormality (thrombocytopenia, elevated INR, hypofibrinogenemia)
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| ##Systemic effects (oral swelling/paresthesias, metallic taste, hypotension, tachycardia)
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| #Absence of all of the above 8-12hr after bite indicates dry bite
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| ===Work-Up===
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| #CBC
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| #Coags
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| #Fibrinogen
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| #FDP
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| #Chemistry
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| ===Treatment===
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| #Local Care
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| ##Do not:
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| ###Attempt to suck out the venom
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| ###Place the affected part in cold water
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| ###Use a tourniquet or wrap
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| ##Do:
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| ###Immobilize limb in a neutral position
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| #Antivenom
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| ##Crotalidae Polyvalent Immune Fab (FabAV)
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| ##Indications:
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| ###Progression of swelling
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| ###Abnormal results on lab tests (plt < 100,000 or fibrinogen < 100)
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| ###Systemic manifestations (unstable vitals or AMS)
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| ##Administration
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| ###The total volume but NOT the number of vials may be reduced in small children
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| ###Establish initial control of envenomation by giving 4-6 vials
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| ####Control achieved? (Cessation of progression of all components of envenomation, including labs checked 2 hours after infusion started)
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| #####If yes infuse 2-vial doses at 6, 12, and 18hr after initial control achieved
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| #####If no repeat infusion of 4-6 vials and then re-evaluate for control
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| ##Envenomation control measurement
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| ###Must observe for progression of envenomation during and after antivenom infusion
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| ####Measure limb circumference at several site above and below bite
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| ####Mark advancing border of edema q30min
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| ####Repeat labs q4hr or after each course of antivenom (whichever is more frequent)
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| ##Side Effects
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| ###Acute reactions occur in <10% pts
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| ###If occurs stop infusion and give antihistamines / epi if needed
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| ##Recurrent thrombocytopenia has been described up to 2 weeks after transfusion with FabAV
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| ###Likely result of isolated renal clearance of FabAV and persistent presence of actual venom in serum
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| ###Only described in patients with history of thrombocytopenia during hospital course
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| ###warrants close monitoring of platelets by PMD or return visit after discharge
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| #Supportive care
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| ##IVF and pressors if needed for hypotension
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| ##Blood component replacement indicated if antivenom fails to stop active bleeding
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| #Compartment Syndrome
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| ##If signs of compartment syndrome are present and pressure >30:
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| ###Elevate limb
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| ###Administer additional FabAV 4-6 vials IV over 60min
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| ###If elevated compartment pressure persists another 60min consider fasciotomy
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| ===Disposition===
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| #Must observe all snakebite pts for at least 8hr before determining patient disposition
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| ##Bites that initially appear innocuous and labs normal at presentation can be deceptive
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| #Discharge if symptom-free after 8hr
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| #Admit all pts receiving antivenom to the ICU
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| #Admit pts to the ward if have completed or do not require further antivenom therapy
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| ==Coral Snakes==
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| ===Background===
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| #All coral snakes are brightly colored with black, red, and yellow rings
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| ##Red and yellow rings touch in coral snakes, but are separated in nonpoisonous mimics
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| ###"Red touch yellow, kills a fellow; red touch black, venom lack"
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| ===Clinical Features===
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| #Local injury is often minimal
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| #Venom effects may develop hours after a bite
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| ===Treatment===
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| #Antivenom
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| ##Give 3-5 vials of Antivenin to ALL pts who have definitely been bitten
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| ###It may not be possible to prevent further effects or reverse effects once they develop
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| ###Additional doses of antivenom are reserved for cases in which symptoms/signs appear
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| #Monitor for respiratory respiratory failure
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| ===Disposition===
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| #Admit all pts (even if initially symptom free)
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| ==Source== | | ==Source== |
| Tintinalli
| | <references/> |
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| [[Category:Environ]] | | [[Category:Environ]] |
| [[Category:Tox]] | | [[Category:Tox]] |
