Snakebites

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Snakebites

• Kirsten Schlenker, RN
• Prehospital Coordinator,
• UPH Hospital

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Snakebites

• 45,000 total bites per year in U.S.
• 8,000 bites from venomous snakes
• 25 are dry bites (no venom injected)
• 10 deaths

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Anatomy of a rattlesnake bite

• Rattlesnake venom has a complex protein makeup
  that includes a variety of enzymes and toxins.
  Rattlesnake venoms have primarily hemorrhagic
  enzyme fractions (hemotoxins), but also include
  neurotoxins and myotoxins to varying degrees. In
  certain local populations of some species, the
  neurotoxins may occur in much higher proportion
  and thus have treatment consequence. When an
  envenomation occurs, there may be both local and
  systemic effects. Local effects may include
  edema, hemorrhage, discoloration and pain.
  Systemic effects may cause changes in the
  respiratory, urinary, cardiovascular and urinary
  systems watch for shock, renal compromise,
  hemolysis, coagulation factors, hypotension and
  more. In rare occasions, rattlesnake bites are
  fatal. In other cases they may result in
  permanent muscle or nerve damage resulting in
  loss of function to the affected area. If gone
  untreated, the likelihood and or severity of any
  of these consequences increases

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Venomous Snakes

• Types of U.S.venomous snakes
• Pit vipers (Crotalidae)
• Rattlesnakes
• Copperheads
• Water moccasins (cotton mouth)
• Coral snakes (Elapidae)

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Venomous Snakes

• Pit vipers
• Heavy bodies
• Triangular-shaped heads
• Vertical or elliptical pupil
• Heat sensing pit on upper lip between eye and
  nostril
• Erectile fangs
• Venom primarily hemotoxic but
• there may be neurotoxic effects

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Venomous Snakes

• Rattlesnakes
• 13 Species in Arizona
• 7,000 bites/year in U.S.
• 9 to 10 fatalities in U.S.
• In Arizona, most deaths are from western
  diamondback and Mojave rattlesnakes

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Venomous Snakes

• Copperhead not found in Arizona
• Agkistrodon contortrix
• Deaths VERY rare
• Minimal edema and pain

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Venomous Snakes

• Water moccasin
• (not found in Arizona)
• Agkistrodon piscivorus
• 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 stored venom may be discharged in a
  bite
• Replenished in 3 to 4 weeks
• Extremities are most common bite site
• Most common victims
• Intoxicated males age 15-40
• Snake handlers and collectors

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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

• Numbness, tingling, and neurological symptoms may
  develop
• Presynaptic Neurotoxic effect
• - Produces few local effects
• - May cause a systemic intoxication
  syndrome
• Decreased level of consciousness
• Cranial nerve dysfunction
• Respiratory paralysis

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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
• 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 (immeasurable pT and
  pTT)
• Thrombocytopenia (platelets lt20,000)

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Venomous Snakes

• Coral snakes
• Two species in the U.S.
• Arizona coral snake
• Non-aggressive
• No recorded human deaths
• Eastern coral snake
• Several bites reported annually (Florida to
  Texas)
• About one death every 5 years

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Venomous Snakes

• Arizona Coral snake
• Thin-bodied, small rounded snout, brightly
  colored ringed pattern, small non-erectile fangs
• Venom usually delivered by chewing
• Venom primarily postsynaptic neurotoxic
• Little to no hemotoxic effects
• Arizona coral snake is docile and rarely bites
• No antivenin is made for this species

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Coral Snake Envenomation

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

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Coral Snake Envenomation(from eastern U.S.
species)

• 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 and reassure the patient
• Secure and maintain airway
• Prepare for immediate transport (do not delay
  treatment for any first aid/treatment measure or
  wait for signs of envenomation to occur)
• Obtain vital signs including O2 saturation
• Oxygen to keep saturation gt 90 (method as best
  tolerated by patient)
• Remove ALL watches, rings, and jewelry (not just
  from affected limb)
• If bite on extremity, immobilize affected
  extremity at or below the level of the heart
  (make sure any immobilization device and practice
  does not result in becoming a tourniquet over
  time due to swelling)
• Mark the proximal edge of any discoloration or
  swelling in ink and write the time on the line
  (if signs increase during transport, make new
  marks with the times)

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Snakebite Management

• Do NOT attempt to
• locate and bring the venomous snake to the
  hospital. If you find it, you will probably make
  a bad scene worse it has already bitten one
  person! There is no medical reason to bring the
  snake in. All local species use the same
  antivenin.

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Do NOT use ice or cold packs. It does not slow
the enzyme activity. It slows the immune-response.
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DO NOT use tourniquets or restricting bands. All
you do is localize all those digestive enzymes.
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DO NOT lance, or use cut and suck methods.
Snakebite is an IM injection. The venom isnt
going to be sucked out. Cutting increases tissue
damage to an area already infiltrated with
digestive enzymes.
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Here is a finger bite progressing well through
proper treatment (note black ink marks where
increases in edema were recorded)
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Special thanks to the following for providing
information and/or photographs.

• Hugh McCrystal
• D. Frank Retes
• Drexel Heights Fire District
• The Arizona-Sonora Desert Museum
• The New York Zoological Society