Snake bites: Difference between revisions
 
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==Crotaline (Pit Vipers)==
==Background==
===Background===
[[File:Coral 009.jpg|thumb|[[Coral snake]]]]
*Includes rattlesnakes and copperheads
[[File:Rattle snake.jpg|thumb|[[Rattlesnake]]]]
*Venom causes local tissue injury, hemolysis, coagulopathy, neuromuscular dysfunction
*Up to 25% of bites are dry bites


===Clinical Features===
*An average of 5000 native venomous snakebites are reported to US poison centers annually<ref>Seifert SA et al. AAPCC database characterization of native U.S. venomous snake exposures, 2001-2005. Clin Toxicol (Phila). 2009;47: 327–335.</ref>
#Fang marks, localized pain, progressive edema extending from bite site
*In the United States, snake bites can be organized into [[Crotaline (Pit Vipers)]] and [[Elapidae (Coral Snakes)]]
##Edema near the airway or in muscle compartment may threaten life or limb
*Crotalidae family also includes rattlesnakes, Sistrurus and Agkistrodon species (water moccasins and copperheads).<ref>Goldfranks Toxicology - Envenomations</ref>
#Nausea/vomiting, oral numbness/tingling, dizziness, muscle fasciculations
*Risk Factors: "The 'T's" Testosterone, Tequila, Tshirt, Tattoos, Toothless, Teasing, Trailer park, Truck
#Ecchymoses may appear within minutes to hours
===Venom===
*Snake venom is a  mixture of proteins, peptides, lipids, and metal ions.
*Many bites can be "dry bites" where no venom is released, about ~1/4


===Diagnosis===
==Clinical Features==
#Must have a snakebite + evidence of tissue injury:
*Local injury - punctures marks from fangs not always visible; erythema, and edema
##Local injury (swelling, pain, ecchymosis)
*Ooze at fang mark reliable sign of envenomation
##Hematologic abnormality (thrombocytopenia, elevated INR, hypofibrinogenemia)
*[[Nausea/vomiting]]
##Systemic effects (oral swelling/paresthesias, metallic taste, hypotension, tachycardia)
#Absence of all of the above 8-12hr after bite indicates dry bite


===Work-Up===
==Differential Diagnosis==
#CBC
{{Bites and stings DDX}}
#Coags
#Fibrinogen
#FDP
#Chemistry


===Treatment===
==Evaluation==
#Local Care
*Clinical Diagnosis
##Do not:
*Evaluate for [[compartment syndrome]] (see below)
###Attempt to suck out the venom
*CBC, coags: [[Thrombocytopenia]] and elevated INR can occur in Crotaline envenomations.
###Place the affected part in cold water
###Use a tourniquet or wrap
##Do:
###Immobilize limb in a neutral position
#Antivenom
##Crotalidae Polyvalent Immune Fab (FabAV)
##Indications:
###Progression of swelling
###Abnormal results on lab tests (plt < 100,000 or fibrinogen < 100)
###Systemic manifestations (unstable vitals or AMS)
##Administration
###The total volume but NOT the number of vials may be reduced in small children
###Establish initial control of envenomation by giving 4-6 vials
####Control achieved? (Cessation of progression of all components of envenomation, including labs checked 2 hours after infusion started)
#####If yes infuse 2-vial doses at 6, 12, and 18hr after initial control achieved
#####If no repeat infusion of 4-6 vials and then re-evaluate for control
##Envenomation control measurement
###Must observe for progression of envenomation during and after antivenom infusion
####Measure limb circumference at several site above and below bite
####Mark advancing border of edema q30min
####Repeat labs q4hr or after each course of antivenom (whichever is more frequent)
##Side Effects
###Acute reactions occur in <10% pts
###If occurs stop infusion and give antihistamines / epi if needed
##Recurrent thrombocytopenia has been described up to 2 weeks after transfusion with FabAV
###Likely result of isolated renal clearance of FabAV and persistent presence of actual venom in serum
###Only described in patients with history of thrombocytopenia during hospital course
###warrants close monitoring of platelets by PMD or return visit after discharge
#Supportive care
##IVF and pressors if needed for hypotension
##Blood component replacement indicated if antivenom fails to stop active bleeding
#Compartment Syndrome
##If signs of compartment syndrome are present and pressure >30:
###Elevate limb
###Administer additional FabAV 4-6 vials IV over 60min
###If elevated compartment pressure persists another 60min consider fasciotomy


===Disposition===
==Management==
#Must observe all snakebite pts for at least 8hr before determining patient disposition
{{Snake bite local treatment}}
##Bites that initially appear innocuous and labs normal at presentation can be deceptive
#Discharge if symptom-free after 8hr
#Admit all pts receiving antivenom to the ICU
#Admit pts to the ward if have completed or do not require further antivenom therapy


==Coral Snakes==
===Supportive care===
===Background===
*[[IVF]] and [[pressors]] if needed for [[hypotension]]
#All coral snakes are brightly colored with black, red, and yellow rings
*[[pRBCs|Blood]] components rarely needed
##Red and yellow rings touch in coral snakes, but are separated in nonpoisonous mimics
*Treatment mainly depends upon the presence of an [[Envenomation|envenomation]]
###"Red touch yellow, kills a fellow; red touch black, venom lack"
*Indications:
**Progression of local injury - pain, swelling, ecchymosis
**[[Coagulopathy]] - elevated PT/PTT/INR, low fibrinogen, thrombocytopenia
**Systemic effects - [[hypotension]], [[altered mental status]], [[nausea and vomiting]], [[paresthesias]]
*Always provide supportive care and treat local effects of any wounds
*Irrigation of the wound is necessary regardless of the type of snake bite
*Debridement and removal of devitalized tissue may be necessary for severe bites
*Evidence does not support use of empiric [[antibiotics]] to prevent secondary infection <ref>Gold B.. Bites of venomous snakes. N Engl J Med. 2002;347(5):347-56.</ref>
*[[Compartment syndrome]] has been documented with crotaline envenomation, but current literature does not support use of fasciotomy. <ref> Cumpston KL. Is there a role for fasciotomy in Crotalinae envenomations in North America? PMID: 21740134 </ref> Treatment should focus on antivenom.


===Clinical Features===
===Antivenom===
#Local injury is often minimal
*Snake specific treatments depend upon [[Coral snake]] or [[Crotaline (Pit Vipers)|Pit viper]] envenomations
#Venom effects may develop hours after a bite


===Treatment===
==Disposition==
#Antivenom
*All snake bites with evidence of envenomations should have a period of observation and possible hospitalization
##Give 3-5 vials of Antivenin to ALL pts who have definitely been bitten
*Old bites can be assessed and discharged if no evidence of envenomation.
###It may not be possible to prevent further effects or reverse effects once they develop
###Additional doses of antivenom are reserved for cases in which symptoms/signs appear
#Monitor for respiratory respiratory failure


===Disposition===
==See Also==
#Admit all pts (even if initially symptom free)
*[[Envenomations, bites and stings]]
*[[Crotaline (Pit Vipers)]]
*[[Elapidae (Coral Snakes)]]


==Source==
==References==
Tintinalli
<references/>


 
[[Category:Environmental]]
[[Category:Environ]]
[[Category:Toxicology]]

Latest revision as of 17:08, 17 March 2021

Background

Coral snake
Rattlesnake
  • An average of 5000 native venomous snakebites are reported to US poison centers annually[1]
  • In the United States, snake bites can be organized into Crotaline (Pit Vipers) and Elapidae (Coral Snakes)
  • Crotalidae family also includes rattlesnakes, Sistrurus and Agkistrodon species (water moccasins and copperheads).[2]
  • Risk Factors: "The 'T's" Testosterone, Tequila, Tshirt, Tattoos, Toothless, Teasing, Trailer park, Truck

Venom

  • Snake venom is a mixture of proteins, peptides, lipids, and metal ions.
  • Many bites can be "dry bites" where no venom is released, about ~1/4

Clinical Features

  • Local injury - punctures marks from fangs not always visible; erythema, and edema
  • Ooze at fang mark reliable sign of envenomation
  • Nausea/vomiting

Differential Diagnosis

Envenomations, bites and stings

Evaluation

Management

Local Care

  • Do:
    • Remove all jewelry
    • Mark the leading edge of erythema/edema
  • Do not:
    • Attempt to suck out the venom
    • Place the affected part in cold water
    • Use a tourniquet or wrap
    • Antivenom is first line treatment for compartment syndrome; fasciotomy is last resort if elevated pressures persist.

Supportive care

  • IVF and pressors if needed for hypotension
  • Blood components rarely needed
  • Treatment mainly depends upon the presence of an envenomation
  • Indications:
  • Always provide supportive care and treat local effects of any wounds
  • Irrigation of the wound is necessary regardless of the type of snake bite
  • Debridement and removal of devitalized tissue may be necessary for severe bites
  • Evidence does not support use of empiric antibiotics to prevent secondary infection [3]
  • Compartment syndrome has been documented with crotaline envenomation, but current literature does not support use of fasciotomy. [4] Treatment should focus on antivenom.

Antivenom

Disposition

  • All snake bites with evidence of envenomations should have a period of observation and possible hospitalization
  • Old bites can be assessed and discharged if no evidence of envenomation.

See Also

References

  1. ↑ Seifert SA et al. AAPCC database characterization of native U.S. venomous snake exposures, 2001-2005. Clin Toxicol (Phila). 2009;47: 327–335.
  2. ↑ Goldfranks Toxicology - Envenomations
  3. ↑ Gold B.. Bites of venomous snakes. N Engl J Med. 2002;347(5):347-56.
  4. ↑ Cumpston KL. Is there a role for fasciotomy in Crotalinae envenomations in North America? PMID: 21740134
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