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Adam Algren, MD Medical Toxicology Fellow Georgia Poison Center Clinical Instructor

Snakes, Spiders, and Creatures from the Sea. Adam Algren, MD Medical Toxicology Fellow Georgia Poison Center Clinical Instructor Emory University Dept. of Emergency Medicine. Objectives. Review clinical manifestations of North American snake envenomations

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Adam Algren, MD Medical Toxicology Fellow Georgia Poison Center Clinical Instructor

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  1. Snakes, Spiders, and Creatures from the Sea Adam Algren, MD Medical Toxicology Fellow Georgia Poison Center Clinical Instructor Emory University Dept. of Emergency Medicine

  2. Objectives • Review clinical manifestations of North American snake envenomations • Review presentation and management of black widow and brown recluse spider bites • Discuss the indications for the use of antivenoms: CroFab and Lactrodectus • Discuss common marine envenomations

  3. Snake Envenomations • Crotalids • Pit Vipers • Found in every state except Alaska, Hawaii, Maine • 6000-8000 bites/yearly • 5-10 deaths/yearly • Elapids • Coral Snake • 69 Bites reported in 2000 • 64% Florida

  4. NEJM 2002;347:350

  5. Crotalids

  6. Crotalids

  7. Crotalids • Crotalus • C. adamanteusEastern Diamondback rattlesnake • C. atrox Western Diamondback rattlesnake • C. horridus horridusTimber rattlesnake • C. horridus atricaudatus Canebrake rattlesnake • C. scutulatus Mojave rattlesnake • C. viridis viridis Prairie rattlesnake • C. cerastes Sidewinder rattlesnake • Sistrurus • S. milarius Pigmy rattlesnake • S. catenatus spp. Massasauga rattlesnake • Agkistrodon • A. contortix Copperheads • A. piscivorus Cottonmouths

  8. Eastern Diamondback RattlesnakeCrotalus adamanteus

  9. Crotalids • Majority of victims are male • Majority of bites occur May-October • >50% victims of provoked bites are intoxicated • ¾ bites occur to upper extremities • 0-75% of snake’s venom is discharged • Venom replenished within 1 month • 5-20% of bites are “dry bites”

  10. Crotalids • Venom • Components • Metalloproteinases • Collagenases • Hyaluronidases • Proteases • Composition/potency varies • Snake • Species • Age • Season NEJM 2002;347:351

  11. Western Diamondback rattlesnakeCrotalus atrox

  12. Crotalid Envenomations • Pathophysiology • Local Effects • Most common • Metalloproteinases and other components damage vascular endothelium and basement membranes • Edema, ecchymosis, blistering • Systemic Effects • Coagulopathy • Hypotension

  13. Crotalid Envenomations • Pre-hospital Management • Avoid exertion • Immobilize the extremity at or below level of heart • Rapid transport to nearest emergency dept. • Consider constriction band if there is going to be a prolonged transport time • Extractor devices probably not helpful • Avoid tourniquet, cryotherapy, electric shock, excision, and incision • McKinney. Ann Emerg Med. 2001;37:168-74. • Alberts. Ann Emerg Med. 2004;43:181-6.

  14. Crotalid Envenomations • History • Circumstance of bite • Type of snake • Number of bites • Time since envenomation • First aid provided • Previous history of snake envenomation/antivenom treatment • Sensitivity to horse/sheep sera • Be cautious with any snakes brought to the ED

  15. CopperheadAkistrodon contortix

  16. Crotalid Envenomations • Clinical Manifestations • Local • Fang marks • Number of fang marks helpful, but not definitive • Edema • Ecchymosis • Bullae

  17. Crotalid Envenomations

  18. Crotalid Envenomations

  19. Crotalid Envenomations • Clinical Manifestations • Systemic • Anaphylaxis • Nausea, vomiting, diaphoresis, metallic taste • Hypotension • Coagulopathy • Thrombocytopenia • Rhabdomyolysis • Neurologic Effects • Mojave rattlesnake

  20. NEJM 2002;347:351

  21. Timber rattlesnakeCrotalus horridus horridus

  22. Canebrake rattlesnakeCrotalus horridus atricaudatus

  23. Mojave rattlesnakeCrotalus scutulatus

  24. Crotalid Envenomations • Treatment • Remove any constriction band slowly • Tetanus • Prophylactic antibiotics unnecessary • Consult poison center • Determine antivenom supplies • Document neurovascular exam for extremity bites • Measure limb circumference every 15 minutes • Labs- CBC, chemistries, PT, PTT, Fibrinogen, CK

  25. CottonmouthsAgkistrodon piscivorus

  26. Crotalid Envenomations • Treatment • Surgical treatment • Routine surgical treatment not recommended • Measure compartment pressures if there is concern • Digit dermotomy • Hall E. Ann Emerg Med. 2001;37:175-180.

  27. Crotalid Envenomations • Antivenom • Wyeth polyvalent antivenom • CroFab • Indications: • Rapid progression of local effects • Compartment syndrome • Coagulopathy, Thrombocytopenia • Neurologic Symptoms • Shock

  28. Crotalid Envenomations • CroFab • FDA approved in 2000 • Sheep derived FabIgG • Less immunogenic • Eastern/Western Diamondback rattlesnake, Mojave rattlesnake, Cottonmouth • Skin testing not required • 0-14% incidence of immediate hypersensitivity • <5% incidence of serum sickness

  29. Crotalid Envenomations • Dart et al. Arch Intern Med. 2001;161:2030-6. • 31 patients • 6 or 12 vials CroFab initially • 16 patients PRN, 15 scheduled • 8 patients in PRN group required additional CroFab • 0 patients in scheduled group • All patients had significant improvement in snakebite severity scores • 6 allergic reactions • 4 urticaria, 1 urticaria/cough, 1 urticaria/dyspnea/wheezing

  30. Crotalid Envenomations • CroFab for Copperhead envenomations • 32 cases • 25 (78%) were moderate severity • 7 had mild laboratory abnormalities • 23 (72%) achieved control with 4 vials • 4 cases progressed following CroFab • No allergic reactions • 1 mild case serum sickness • Lavonas et al. Ann Emerg Med. 2004;43:200-6.

  31. Crotalid Envenomations • Safety and Efficacy of CroFab for Pediatric Envenomations • 24 patients • Mean age 7.3 (range 1.9-13) • All had local swelling • 14 (58%) PT >13sec • 3 (12.5%) platelets <150,000 • 2 (8.3%) fibrinogen <150 mg/dl • Mean number of CroFab vials used 12.3 (4-24) • 5 patients progressive thrombocytopenia • ? 1 allergic reaction • Pizon et al. Acad. Emerg Med. 2007;14:373-6.

  32. Crotalid Envenomations • Recurrence- Local or systemic • Possible explanations • Pharmacokinetic/pharmacodynamic mismatch of venom/antivenom • CroFab elimination ½ life 15-20 hours • Late onset of venom effects • Prolonged absorption of venom from wound • Dissociation of venom/antivenom complex • Development of host anti-antivenom response

  33. Crotalid Envenomations • Post-marketing study of CroFab for rattlesnakes • 28 patients (3 children) • 16/28 achieved local control with 4-6 vials • 20/28 elevated PT, 6/28 thrombocytopenia, 12/28 hypofibrinogenemia • Control achieved in all, 67-80% required >10 vials • 6/21 had systemic recurrence • No significant bleeding • No anaphylactic reactions • Ruha et al. Ann Emerg Med. 2002;39:609-615

  34. Ann Emerg Med 2001;37:2

  35. Ann Emerg Med 2001;37:2

  36. Crotalid Envenomation • Disposition • Observe for 6-8 hours if asymptomatic • May discharge if asymptomatic with normal labs • Admit all suspected Mojave rattlesnake envenomations for 24 hours • Admit for significant local effects or if labs abnormal

  37. Which snake is poisonous? King snake Lampropeltis getulus Coral Snake Micrurus fulvius “Red on yellow, kill a fellow” “Red on black, venom lack”

  38. Coral Snake Envenomations • Uncommon • Florida, Georgia • Eastern, Texas, Sonoran • Small, ~40 inches full grown, small teeth • 25% of bites are “dry bites” • Venom • Components not well understood • Zinc dependent acetylcholinesterase

  39. Coral Snake Envenomations • Clinical Presentation • 1/3 have mild local swelling • Mild systemic symptoms • May develop localized pain or fasciculations • Neurologic symptoms • Normal mental status • CN palsies, weakness/paralysis, respiratory failure • Avg. delay to symptom onset is ~ 2 hours • May be delayed up to 13 hours • Kitchens et al. JAMA. 1987;258:1615-8.

  40. Coral Snake Envenomations • Treatment • Supportive Care • Aggressive airway management, monitor NIF • Consult poison center, determine antivenom supplies • Consider Neostigmine • Early antivenom administration even if asymptomatic • Equine derived • 3-5 vials initially, redose additional 5 vials in symptomatic pts • Reconstitution 15-30 minutes • Immediate hypersenitivity- 6/17 urticaria, 1/39 anaphylaxis • Serum sickness- 4/39 patients

  41. Coral Snake Envenomations • Disposition • Admit all suspected Coral snake bites for at least 24 hours

  42. Black Widow Envenomations

  43. Black Widow Envenomations • Latrodectus mactans • ~2500 bites/year • 300-400 severe • Prefer dry, dark environments • Only females envenomate • No deaths in US in past 20 years • α-lactrotoxin • Stimulates release of acetylcholine and catecholamines

  44. Black Widow Envenomations • Non-specific symptoms can make diagnosis difficult • Bite is not always felt • Pain within 10-60 min, but may be delayed • 75% will only have local symptoms • Pain, diaphoresis, piloerection • Systemic symptoms may develop over several hours • Generalized pain, abdominal pain, priapism, diaphoresis, tachycardia, hypertension, headache, vomiting, tremor • Symptoms peak within 12-24 hours • Typically resolves over 24-72 hours

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