Envenomation

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Envenomation

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

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Objectives

• Review common (?) envenomations
• Brief review of biology
• Principles of prevention, diagnosis and management

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Envenomations Outline

• Arthropods
• Insects (Hymenoptera)
• Spiders (Arachnid)
• Scorpions (Arachnid)
• Reptiles
• Pit Vipers (Crotalidae)
• Coral Snakes (Elapidae)
• Venomous Marine Life

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ARTHROPODS
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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)

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Venomous Bites and Stings

• 50 insect sting
• 30 snake bite
• 14 spider bite
• 6 other

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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

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Hymenoptera

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

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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!

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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

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Hymenoptera

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

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Hymenoptera

• Systemic reactions
• Most deaths (75) occur within 4 hours of the
  sting

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Hymenoptera

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

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Hymenoptera

• Treatment of Severe Reactions (Anaphylaxis)
• Activate EMS
• Airway management
• Epinephrine (0.3 cc of 11,000 soln q15 min) SQ
  or IM
• Fluids
• Antihistamines

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Medications for Anaphylaxis

• Diphenhydramine
• 50 mg PO/IM q4-6h (may also give IV)
• Epinephrine (11,000)
• 0.3 cc of 11,000 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)

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Allergic Responses

• Grade 1
• Enlarging local response at sting site
• Cold compresses
• Symptomatic medications

• Grade 2
• Generalized urticaria
• Diphenhydramine
• Epinephrine (if severe)

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Allergic Responses

• 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

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Hymenoptera

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

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Hymenoptera

• Treatment
• Self treatment
• Medic Alert Tags
• Anaphylaxis kit
• Hyposensitization therapy

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Subphylum CheliceradaClass Arachnida
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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)

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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

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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

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Black Widow

• Local discomfort (bite site)
• Wound care
• Ice
• Analgesia
• Observe for progression

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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)

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Black Widow

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

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Black Widow

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

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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

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Brown Recluse

• Local effects
• Tissue necrosis
• Edema
• Hemorrhage
• Thrombosis

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Brown Recluse

• Systemic effects
• Due to hemolytic effects of toxin
• Anemia/DIC/renal failure

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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

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Brown Recluse

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

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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

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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

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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

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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

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Scorpion Bites

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

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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

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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 useavoid
  oversedation
• Phenobarb (5-10mg/kg) or diazepam

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Kingdom AnimaliaPhylum ChordataSubphylum
VertebrataClass Reptilia
Eyelash Viper
Eastern D-Back
Copperhead
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Reptiles
Timber
Coral Snake
Copperhead
Eastern D-Back
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Snakes

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

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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)

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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

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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
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Pit Vipers (Crotalidae)

• Copperhead
• Agkistrodon contortrix
• Deaths VERY rare
• Minimal edema and pain

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Pit Vipers (Crotalidae)

• Water moccasin
• Agkistrodon piscivorus leucostoma
• Causes an average of one death a year
• Produces mild systemic symptoms, potential for
  severe local tissue injury and necrosis

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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

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Epidemiology

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

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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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Pit Viper Envenomation

• Weakness, sweating, nausea, vomiting
• Tachycardia
• Hypotension, shock
• Prolonged clotting times
• Bleeding gums
• Hematemesis, melena, hematuria

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Pit Viper Envenomation

• Grade of envenomation determines need for
  antivenom

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Grading of Pit Viper Envenomation

• Dry Bite
• Local abrasion or bite mark without severe pain
  or swelling
• Normal vital signs
• Normal coagulation studies
• Normal platelet count

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Grading of Pit Viper Envenomation

• Mild Envenomation
• Local pain and swelling
• Normal vital signs
• Normal to mildly abnormal coagulation studies
• Platelet count gt100,000

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Grading of Pit Viper Envenomation

• Moderate Envenomation
• Local pain and moderate swelling (gt12 from bite
  site)
• Normal vital signs
• Abnormal coagulation studies (doubling of pT and
  pTT)
• Thrombocytopenia (platelets lt100,000)

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Grading of Pit Viper Envenomation

• Severe Envenomation
• Initial presentation consistent with shock
• Altered mental status with or without normal
  vital signs and/or poor peripheral perfusion
• Abnormal coagulation studies (PTTgt50 INR gt 3
  fibrinogen lt 50)
• Thrombocytopenia (platelets lt20,000)

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Antivenom

• Crotalinae
• Polyvalent ovine Fab (Crofab Protherics,
  Nashville, TN) FabAV www.protherics.com
• Eastern/Western/Mojave rattlesnake cottonmouth
  (OK to treat copperhead as well)
• Sheep immunoglobulin Fab fragments
• 4-6 vial initial dose
• 4-6 vial f/u dose if no response in 1 hour (based
  on clinical parameters and coags)

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Elapidae

• Coral snake
• Thin-bodied
• Small, rounded head
• Brightly colored
• Small fixed fangs
• Injects venom by chewing
• Venom primarily neurotoxic

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Elapidae

• Coral snake
• Arizona coral snake
• Non-aggressive
• No recorded human deaths
• Eastern coral snake
• Several bites reported annually (mostly Florida,
  Texas)
• About one death every 5 years

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Elapidae Envenomation

• Little, no pain
• Little, no swelling
• Paresthesias around bitten area
• Muscular incoordination, weakness

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Elapidae Envenomation

• Increased salivation
• Difficulty swallowing, talking
• Visual disturbances
• Respiratory distress, failure
• Shock, cardiovascular collapse

Most deaths occur from respiratory arrest within
36 hours
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Snakebite Management

• Calm victim
• Oxygen, monitor, IV
• Proximal constricting band ( )
• Clean, bandage wound
• Immobilize bitten area, keep dependent
• Watch constricting bands, bandages, splints
  carefully for vascular compromise 2o to edema
• Transport

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Snakebite Management

• Do NOT
• Apply ice
• Apply arterial tourniquet
• Cut and suck
• Use electrical shock
• Actively attempt to locate a venomous snake
• Bring a live venomous snake to the hospital

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Envenomation from Marine LifeKingdom
AnimaliaPhylum Cnidaria
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Venomous Marine Life

• Jellyfish, Portuguese man-of-war, fire corals
• Stinging cells (nematocysts) in tentacles.
  Function even when separated from organism!
• Venom is antigenic

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Jellyfish

• Intense, burning pain
• Red, hemorrhagic lesions
• Nausea, vomiting
• Fever, chills
• Respiratory distress, wheezing, stridor
• Hypotension, shock
• Cardiovascular collapse

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Jellyfish

• Remove tentacles (gloves/forceps)
• Can also use shaving cream/baking soda and
  shave nematocysts
• Vinegar can block discharge of nematocysts!
  Apply liberally.

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Venomous Marine Life

• Venomous Fish
• Stingray
• Scorpionfish, Lion fish, Stonefish

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Stingrays

• 1500 bites/year in US
• Spine at base of tail with venom gland
  (vasoconstrictive)
• Pain, salivation, N/V, diarrhea, cramps, dyspnea,
  headache

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Mechanism

• Typically step on unsuspecting stingray
• Puncture wound to feet are most common

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Stingray Management

• Rinse area and remove spine
• Soak in warm water, cleanse wound
• Update tetanus
• Antibiotics usually not necessary.

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Venomous Marine Life

• Sea Urchins (Echinoderms)
• Toxin-coated spines that fracture

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Echinodermata Management

• Symptoms
• Pain, burning, discoloration of skin
• Immerse injured area in hot water
• Use acetic acid to dissolve embedded spines
• Larger spines may require surgical removal

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Managing Marine Envenomations

• Remove patient from water
• Assess and control ABCs
• Do not remove wet suit
• Attempt to ID Critter

• Transport to care as necessary
• Irrigate the wound with normal saline (vinegar as
  appropriate)
• Debride wound if needed. Avoid suturing if
  possible.

Perkins Morgan. AFP 2004 69 885-890
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Questions

• Mbstephens_at_nhcl.med.navy.mil