Diferencia entre revisiones de «Crotaline envenomation»
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==Clinical Features== | ==Clinical Features== | ||
*Fang marks, localized pain, progressive edema extending from bite site | |||
**Edema near the airway or in muscle compartment may threaten life or limb | |||
*Nausea/vomiting, oral numbness/tingling, dizziness, muscle fasciculations | |||
*Ecchymoses may appear within minutes to hours | |||
==Diagnosis== | ==Diagnosis== | ||
*Must have a snakebite + evidence of tissue injury: | |||
**Local injury (swelling, pain, ecchymosis) | |||
**Hematologic abnormality (thrombocytopenia, elevated INR, hypofibrinogenemia) | |||
**Systemic effects (oral swelling/paresthesias, metallic taste, hypotension, tachycardia) | |||
*Absence of all of the above 8-12hr after bite indicates dry bite | |||
==Work-Up== | ==Work-Up== | ||
*CBC | |||
*Coags | |||
*Fibrinogen | |||
*FDP | |||
*Chemistry | |||
==Differential Diagnosis== | ==Differential Diagnosis== | ||
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==Treatment== | ==Treatment== | ||
*Local Care | |||
**Do not: | |||
***Attempt to suck out the venom | |||
***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== | ==Disposition== | ||
*Must observe all snakebite pts for at least 8hr before determining patient disposition | |||
**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 | |||
==See Also== | ==See Also== | ||
Revisión del 01:13 12 mar 2015
Background
- Includes rattlesnakes and copperheads
- Venom causes local tissue injury, hemolysis, coagulopathy, neuromuscular dysfunction
- Up to 25% of bites are dry bites
Clinical Features
- Fang marks, localized pain, progressive edema extending from bite site
- Edema near the airway or in muscle compartment may threaten life or limb
- Nausea/vomiting, oral numbness/tingling, dizziness, muscle fasciculations
- Ecchymoses may appear within minutes to hours
Diagnosis
- Must have a snakebite + evidence of tissue injury:
- Local injury (swelling, pain, ecchymosis)
- Hematologic abnormality (thrombocytopenia, elevated INR, hypofibrinogenemia)
- Systemic effects (oral swelling/paresthesias, metallic taste, hypotension, tachycardia)
- Absence of all of the above 8-12hr after bite indicates dry bite
Work-Up
- CBC
- Coags
- Fibrinogen
- FDP
- Chemistry
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
Treatment
- Local Care
- Do not:
- Attempt to suck out the venom
- Place the affected part in cold water
- Use a tourniquet or wrap
- Do:
- Immobilize limb in a neutral position
- Do not:
- 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
- Control achieved? (Cessation of progression of all components of envenomation, including labs checked 2 hours after infusion started)
- 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)
- Must observe for progression of envenomation during and after antivenom infusion
- 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
- If signs of compartment syndrome are present and pressure >30:
Disposition
- Must observe all snakebite pts for at least 8hr before determining patient disposition
- 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