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Envenomation

Envenomation. Mark B. Stephens, MD MS FAAFP Associate Program Director NHCL-FMR (Camp Lejeune). Objectives. Review ‘common’ (?) envenomations Brief review of biology Principles of prevention, diagnosis and management. Envenomations: Outline. Arthropods Insects (Hymenoptera)

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Envenomation

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  1. Envenomation Mark B. Stephens, MD MS FAAFP Associate Program Director NHCL-FMR (Camp Lejeune)

  2. Objectives • Review ‘common’ (?) envenomations • Brief review of biology • Principles of prevention, diagnosis and management

  3. Envenomations: Outline • Arthropods • Insects (Hymenoptera) • Spiders (Arachnid) • Scorpions (Arachnid) • Reptiles • Pit Vipers (Crotalidae) • Coral Snakes (Elapidae) • Venomous Marine Life

  4. ARTHROPODS

  5. Phylum Arthropoda • Invertebrate, articulate-legged animals • At least 1 billion species (95% of total) • Most successful life forms on earth • 4 Subphyla • Trilobites (extinct) • Chilicerates (spiders, scorpions, ticks) • Uniramia (centipedes, millipedes, insects) • Crustacea (crabs, lobster, shrimp)

  6. Venomous Bites and Stings • 50% insect sting • 30% snake bite • 14% spider bite • 6% other

  7. Class: Insecta Order: Hymenoptera • Bees, wasps, ants • Account for more envenomation deaths than anything else! • 10 million stings/year • 40-150 deaths/year • Death usually due to immunologically medicated mechanism

  8. Hymenoptera • Problems • Allergic reactions • Anaphylaxis • Toxic venom effects (rare) • About 40-150 deaths/year • Honeybees 50% • Yellowjackets and other wasps 50%

  9. Hymenoptera • 0.4% of population at risk for serious allergic reaction • Most give history of progressive severity of response • Some deny prior stings or report only normal reactions • 50% of 2006 sting patients experiencing allergic reaction had NO previous warning symptoms!

  10. Hymenoptera • Local reaction (wheal/urticaria) • Sharp, burning pain • Pruritis • Edema • Extensive reactions may involve entire extremity • Stings to tongue/throat may cause loss of airway

  11. Hymenoptera • Systemic reactions • Mild: Diffuse itching, urticaria, swelling distant from sting site, flushing • Severe: Laryngeal edema, severe bronchospasms, profound hypotension

  12. Hymenoptera • Systemic reactions • Most deaths (75%) occur within 4 hours of the sting

  13. Hymenoptera • Treatment • Local Reactions • Remove retained stinger (flick) • Ice to site • Oral antihistamines • Mild analgesics

  14. Hymenoptera • Treatment of Severe Reactions (Anaphylaxis) • Activate EMS • Airway management • Epinephrine (0.3 cc of 1:1,000 soln q15 min) SQ or IM • Fluids • Antihistamines

  15. Medications for Anaphylaxis • Diphenhydramine • 50 mg PO/IM q4-6h (may also give IV) • Epinephrine (1:1,000) • 0.3 cc of 1:1,000 solution q 15 min • Avoid IV, but if necessary use 1: 10,000 soln • Cimetidine • 300-800 mg IV q6h (may also use ranitidine) • Methylprednisolone 125mg IV load, 40mg q6h • Albuterol (for bronchospasm)

  16. Grade 1 Enlarging local response at sting site Cold compresses Symptomatic medications Grade 2 Generalized urticaria Diphenhydramine Epinephrine (if severe) Allergic Responses

  17. Grade 3 Dyspnea, wheeze, angioneurotic edema, nausea Dihpenhydramine Epinephrine Admit for observation If severe, treat as 4 Grade 4 (Anaphylaxis) Dyspnea, dysphagia, hypotension, laryngeal edema Intubatation/Fluids Antihistamines Epinephrine Steroids ICU admission Allergic Responses

  18. Hymenoptera • Treatment • Prevent subsequent sting • Avoid exposure • No bright clothing • Avoid sweet fragrances • Avoid eating sweets outdoors

  19. Hymenoptera • Treatment • Self treatment • Medic Alert Tags • Anaphylaxis kit • Hyposensitization therapy

  20. Subphylum CheliceradaClass Arachnida

  21. Spiders • 50,000 species • 50 U.S. species can bite humans • 15 U.S. species will produce symptoms • Two are particularly dangerous • Black widow (Latrodectus mactans) • Brown recluse (Loxosceles reclusa)

  22. Black Widow (Lactrodectus) • Throughout U.S. • As far north as Oregon, New York • Common in South, Southwest • Irregular webs in wood piles, under rocks, in trash dumps, in outdoor structures • Occasionally in houses • Females rarely leave web • Only females can bite humans

  23. Black Widow • Neurotoxic venom (alpha-latrotoxin) • Binds to nerve-ending calcium channels • Triggers neurotransmitter release • Blocks neurotransmitter re-uptake • Inhibits normal nerve impulse transmission • Produces low serum calcium

  24. Black Widow • Local discomfort (bite site) • Wound care • Ice • Analgesia • Observe for progression

  25. Black Widow • Systemic Symptoms • Neuromuscular twitching, cramping • Calcium gluconate infusion • Diazepam 5-10 mg IV • Methocarbamol 10 mg • Severe pain • Codeine • Morphine • Hypertension • Pain control/sedation • Nitroprusside (rarely)

  26. Black Widow • Symptoms peak in a few hours, then diminish • Usually last < 24 hours • Some symptomatic up to 4 days • 5% have delayed hypersensitivity 2 to 3 days post-bite • Mortality rate unknown • Most recover completely

  27. Black Widow • Antivenin indicated for: • Very young • Very old • Hypertensive reactions • Acute respiratory distress • Horse serum based antivenin (Merck) • 1-2 vials

  28. Brown Recluse (Loxosceles) • Southeast and South Central U.S. • Related species in desert Southwest • Shy, nocturnal • Dark closets, basements • May live on floors, behind furniture in houses • Venom damages endothelial cells

  29. Brown Recluse • Local effects • Tissue necrosis • Edema • Hemorrhage • Thrombosis

  30. Brown Recluse • Systemic effects • Due to hemolytic effects of toxin • Anemia/DIC/renal failure

  31. Brown Recluse • Local signs and symptoms • No pain or only mild stinging • Within 2 hours: Local pain, blue-gray constrictive halo • 12 to 18 hours: Bleb formation, growing ischemic zone • 5 to 7 days: Aseptic necrosis, eschar formation, necrotic ulcer • Severe lesions up to 30 cm in diameter

  32. Brown Recluse • Management of minor (local) bites • Local cold application • Wound cleansing • Padded splint, bulky dressing • Tetanus update

  33. Brown Recluse • Hospital management (systemic loxoscelism) • Supportive and symptomatic care • Debride full thickness lesions with subsequent grafts • Dapsone may improve outcomes • Antivenin under development • Outcomes NOT improved by • Early excision • Steroids

  34. Tarantulas • Large, wandering predatory spiders • About 30 U.S.species • Relatively docile • Rarely bite • Bite produces local pain, edema, lymph node swelling • Flick irritating abdominal hairs if bothered

  35. Scorpions • 40 U.S. species • Only one potentially lethal (Centuroides exilicauda) • Primarily in Arizona • Occasionally in western New Mexico, southeast California, northern Mexico, far West Texas • No deaths since 1969

  36. Scorpion Bites • Neurotoxic venom • Acts on neuronal synapse and neuro-muscular junction • Increased neuron sodium permeability • Neurotransmitter release at synapses • Increased acetylcholine release at neuromuscular junction

  37. Scorpion Bites • Local signs, symptoms • No local swelling or inflammation • Local pain with hyperesthesia • Treat symptomatically. • Ice to area, mild analgesic, wound care

  38. Scorpion Bites • Systemic signs, symptoms • Extreme restlessness, agitation • Roving eye movements • Poor coordination, slurred speech, difficulty swallowing (bulbar findings) • Salivation, wheezing, stridor • Tachycardia, tachypnea, hypertension, nausea, vomiting

  39. Scorpion Bites • Treatment of severe envenomation • Antivenin • Arizona Poison Control 1-800-362-0101 • Give IV. Skin test precautions. 1-2 vials total. (Goat serum product) • Sedatives? • Caution, particularly with antivenin use—avoid oversedation • Phenobarb (5-10mg/kg) or diazepam

  40. Kingdom: AnimaliaPhylum: ChordataSubphylum: VertebrataClass: Reptilia Eyelash Viper Eastern D-Back Copperhead

  41. Reptiles Coral Snake Timber Copperhead Eastern D-Back

  42. Snakes • 45,000 bites per year in U.S. • 8,000 bites from venomous snakes • 25% are dry strikes • 10 deaths

  43. Venomous Snakes • Types of U.S.venomous snakes • Pit vipers (Crotalidae) • Rattlesnakes • Copperheads • Water moccasins (cotton mouth) • Coral snakes (Elapidae) • Cobras, mambas, kraits (not in US)

  44. Venomous Snakes • Pit vipers • Heavy bodies • Diamond-shaped heads • Vertical, elliptical pupil • Heat sensing pit on upper lip between eye and nostril • Moveable fangs • Venom primarily hemotoxic, necrotoxic

  45. Pit Vipers (Crotalidae) • Rattlesnakes • 13 Species • 7,000 bites/year • 9 to 10 fatalities • Most deaths are from western diamondback or eastern diamondback Eastern Diamondback

  46. Pit Vipers (Crotalidae) • Copperhead • Agkistrodon contortrix • Deaths VERY rare • Minimal edema and pain

  47. Pit Vipers (Crotalidae) • Watermoccasin • Agkistrodon piscivorus leucostoma • Causes an average of one death a year • Produces mild systemic symptoms, potential for severe local tissue injury and necrosis

  48. Epidemiology • 25% are dry bites • 25-75% of venom is discharged in a bite • Replenished in 3 to 4 weeks • Extremities are most common bite site • Most common victims: • Children • Intoxicated adults • Snake handlers and collectors

  49. Epidemiology • Risk Factors • Tequila • Testosterone • Tattoo • Teeth (more missing = greater chance) • Trailer park • T-shirt (Heavy Metal Band)

  50. Pit Viper Envenomation • Pain, swelling at bite site • Progressive edema of bitten extremity • Bruising of bitten area • Formation of blood-filled vesicles

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