Crotaline envenomation: Difference between revisions
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==Background== | ==Background== | ||
*The Crotalinae subfamily of Viperidae classifies the new world vipers, or ''pit vipers''. The snakes have a pitlike depression behind the nostril that contains a heat-sensing organ used to find prey. | |||
*The Crotalinae subfamily of Viperidae classifies the | |||
*Includes rattlesnakes and copperheads | *Includes rattlesnakes and copperheads | ||
*Venom causes local tissue injury, | *Venom causes local tissue injury, [[coagulopathy]],and [[thrombocytopenia]] | ||
*Up to 25% of bites are dry bites | *Up to 25% of bites are dry bites | ||
===Common Crotaline snake names=== | |||
===Common Crotaline (Pit Viper) snake names=== | |||
*Rattlesnake | *Rattlesnake | ||
*Cottonmouth | *Cottonmouth | ||
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*Water moccasin | *Water moccasin | ||
*Massasauga | *Massasauga | ||
===Venom=== | ===Venom=== | ||
*Venom form a Crotaline mainly damages local tissue via metalloproteinases and hyaluronidase which cause swelling edema and damage to capillaries. | *Venom form a Crotaline mainly damages local tissue via metalloproteinases and hyaluronidase which cause swelling edema and damage to capillaries. | ||
*Clinical effects consist of: | *Clinical effects consist of: | ||
** | **Local tissue damage | ||
** | **[[coagulopathy|Coagulopathies]] (pro and anti effects) | ||
**Platelet dysfunction | **[[thrombocytopenia|Platelet dysfunction]] | ||
**Neurotoxic effects | **Neurotoxic effects | ||
[[File:Rattle snake.jpg|thumb|[[Rattlesnake]]]] | |||
==Clinical Features== | ==Clinical Features== | ||
*Fang marks, localized pain, progressive edema extending from bite site | *Fang marks, localized pain, progressive edema extending from bite site | ||
*[[Nausea/vomiting]] | |||
*[[Nausea/vomiting]] | *Oral [[numbness]]/tingling | ||
*[[Dizziness]] | |||
*Muscle fasciculations | |||
*Ecchymoses may appear within minutes to hours | *Ecchymoses may appear within minutes to hours | ||
==Differential Diagnosis== | ==Differential Diagnosis== | ||
*[[Necrotizing fasciitis]] | |||
*[[Cellulitis]] | |||
*[[Allergic Reaction]] | |||
{{Bites and stings DDX}} | {{Bites and stings DDX}} | ||
== | ==Evaluation== | ||
===Work-Up=== | ===Work-Up=== | ||
*CBC | *CBC | ||
*Coags | *Coags | ||
*Fibrinogen | *Fibrinogen | ||
*Chemistry | *Chemistry | ||
===Evaluation=== | ===Evaluation=== | ||
*Local injury (pain, progressive swelling, [[compartment syndrome]], lymphangitic spread with pain in the axillae for upper extremity bites or pain in the inguinal region for lower extremity) | |||
*Hematologic abnormality ([[thrombocytopenia]], prolonged PT, hypofibrinogenemia) - [[DIC]]-like syndrome | |||
*Systemic effects ([[hypotension]] resulting from third spacing) | |||
==Management== | ==Management== | ||
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*See below | *See below | ||
===Supportive care=== | ===Supportive care=== | ||
*IVF and | *[[IVF]] and [[vasopressors]] if needed for hypotension | ||
*Blood | *Blood products rarely needed | ||
==Crotalidae Polyvalent Immune Fab (FabAV) Antivenin ([[Crofab]])== | ==Crotalidae Polyvalent Immune Fab (FabAV) Antivenin ([[Crofab]])== | ||
===Indications=== | ===Indications=== | ||
The following are criteria for administration after Crotalidae bite [3] | |||
*Progression of swelling | |||
*Abnormal results on lab tests (platelet < 100,000 or fibrinogen < 100) | |||
*Systemic manifestations (unstable vitals or altered mental status) | |||
{{Crofab dosing}} | {{Crofab dosing}} | ||
==Disposition== | ==Disposition== | ||
* | *Observe all snakebite patients for at least 6hr before determining patient disposition | ||
**Bites that initially appear innocuous and labs normal at presentation can be deceptive | **Bites that initially appear innocuous and labs normal at presentation can be deceptive | ||
*Discharge if symptom-free after | *Discharge if symptom-free after 6hr | ||
*Admit all patients receiving antivenom to the ICU | *Admit all patients receiving antivenom to the ICU | ||
==See Also== | ==See Also== | ||
*[[Snake bites]] | *[[Snake bites]] | ||
*[[ | *[[Envenomations, bites and stings]] | ||
*[[Crofab]] | *[[Crotalidae polyvalent immune Fab (Crofab)]] | ||
==References== | ==References== |
Revision as of 17:28, 28 September 2019
Background
- The Crotalinae subfamily of Viperidae classifies the new world vipers, or pit vipers. The snakes have a pitlike depression behind the nostril that contains a heat-sensing organ used to find prey.
- Includes rattlesnakes and copperheads
- Venom causes local tissue injury, coagulopathy,and thrombocytopenia
- Up to 25% of bites are dry bites
Common Crotaline (Pit Viper) snake names
- Rattlesnake
- Cottonmouth
- Copperhead
- Sidewinder
- Water moccasin
- Massasauga
Venom
- Venom form a Crotaline mainly damages local tissue via metalloproteinases and hyaluronidase which cause swelling edema and damage to capillaries.
- Clinical effects consist of:
- Local tissue damage
- Coagulopathies (pro and anti effects)
- Platelet dysfunction
- Neurotoxic effects
Clinical Features
- Fang marks, localized pain, progressive edema extending from bite site
- Nausea/vomiting
- Oral numbness/tingling
- Dizziness
- Muscle fasciculations
- Ecchymoses may appear within minutes to hours
Differential Diagnosis
Envenomations, bites and stings
- Hymenoptera stings (bees, wasps, ants)
- Mammalian bites
- Closed fist infection (Fight bite)
- Dog bite
- Marine toxins and envenomations
- Toxins (ciguatera, neurotoxic shellfish poisoning, paralytic shellfish poisoning, scombroid, tetrodotoxin
- Stingers (stingray injury)
- Venomous fish (catfish, zebrafish, scorpion fish, stonefish, cone shells, lionfish, sea urchins)
- Nematocysts (coral reef, fire coral, box jellyfish, sea wasp, portuguese man-of-war, sea anemones)
- Phylum porifera (sponges)
- Bites (alligator/crocodile, octopus, shark)
- Scorpion envenomation
- Reptile envenomation
- Spider bites
Evaluation
Work-Up
- CBC
- Coags
- Fibrinogen
- Chemistry
Evaluation
- Local injury (pain, progressive swelling, compartment syndrome, lymphangitic spread with pain in the axillae for upper extremity bites or pain in the inguinal region for lower extremity)
- Hematologic abnormality (thrombocytopenia, prolonged PT, hypofibrinogenemia) - DIC-like syndrome
- Systemic effects (hypotension resulting from third spacing)
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.
Crofab administration
- See below
Supportive care
- IVF and vasopressors if needed for hypotension
- Blood products rarely needed
Crotalidae Polyvalent Immune Fab (FabAV) Antivenin (Crofab)
Indications
The following are criteria for administration after Crotalidae bite [3]
- Progression of swelling
- Abnormal results on lab tests (platelet < 100,000 or fibrinogen < 100)
- Systemic manifestations (unstable vitals or altered mental status)
Initial Administration
- Initial dose: 6 vials[1]
- Typically diluted into 250 cc or 1 L of normal saline and infused over an hour
- Same dose for both adults and pediatrics (may have to adjust the dilution of CroFab for small children so that they are not volume overloaded)
Maintenance therapy
- May repeat dose (2 vials) at 6, 12, and 18 hours later if symptoms not controlled[2]
- Maintance therapy may be indicated after initial dosing based on local protocols even if control is achieved.[3]
Envenomation control measurement
- Observe for progression of envenomation during and after antivenom infusion
- Measure limb circumference at several sites 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 allergic reactions occur in <10% pts
- If occurs stop infusion and give epinephrine/antihistamines if needed
- Recurrent thrombocytopenia has been described up to 2 weeks after transfusion with FabAV and is likely a result of isolated renal clearance of FabAV and persistent presence of actual venom in serum.[4]
- Warrants close monitoring of platelets by primary physician or return visit after discharge
- Serum sickness is unlikely but precautions should be given to patents upon discharge
Disposition
- Observe all snakebite patients for at least 6hr before determining patient disposition
- Bites that initially appear innocuous and labs normal at presentation can be deceptive
- Discharge if symptom-free after 6hr
- Admit all patients receiving antivenom to the ICU
See Also
References
- ↑ Gerardo CJ. The efficacy of crotalidea polyvalent immune fab (ovine) antivenom versus placebo plus optional rescue therapy on recovery from copperhead snake envenomation: A randomized, double-blind, placebo-controlled, clinical trial. Annals of EM. August 2017. 70(2):233-244.
- ↑ Gerardo CJ. The efficacy of crotalidea polyvalent immune fab (ovine) antivenom versus placebo plus optional rescue therapy on recovery from copperhead snake envenomation: A randomized, double-blind, placebo-controlled, clinical trial. Annals of EM. August 2017. 70(2):233-244.
- ↑ Crofab treatment agorithmn http://www.crofab.com/documents/CroFab-Treatment_Algorithm.pdf
- ↑ Ruha AM et al. Late hematologic toxicity following treatment of rattlesnake envenomation with crotalidae polyvalent immune Fab antivenom. Toxicon. 2011;57:53–59.