Snake Bites

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Snake Bites

• Ruma Rajbhandari and Beth Riviello
• Rwinkwavu Hospital, Rwanda
• November 10, 2008

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Background

• 125,000 deaths per year worldwide
• Four families of snakes have venom that is toxic
  to humans
• Atractaspididae
• Colubridae
• Elapidae
• Viperidae
• (Boidae no venom, but is lethal)

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Background

• Rwanda has snakes from all five families, 51
  types of snakes in total.
• Good news only 13 of these snakes have
  potentially serious clinical syndromes
• Bad news
• Only 9 of these can be treated with antivenom
• Only 6 are covered by the one antivenom that we
  hope to get at Rwinkwavu Hospital

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Background

• Puff adder (Viperidae) and African spitting
  cobras (Elapidae)--most death and morbidity in
  Africa
• Nigerian study snake bite mortality 12.2
• When a snake bites more than one human in rapid
  succession, the 2nd or 3rd victim may be more
  severely envenomed than the 1st
• Complex venom gt20 components
• Most Elapidae (mamba) deaths hours
• Viper (puff adder) deaths days

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Background Rwandas 51 snakes
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Family Atractaspididae

• Atractaspis irregularis (Variable Burrowing Asp)
• Indirect cardiotoxins, local necrosis
• No antivenom

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Family Boidae

• Python sebae (African rock python)
• No venom, do constrict victims or even swallow!
• No antivenom

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Family Colubridae

• Dispholidus typus (Boomslang)

• Toxicodryas blandingii (Blanding's Tree Snake)

• Postsynaptic neurotoxin, anticholinesterase
• No antivenom

• Coagulopathy and hemorrhaage
• SAIMR Boomslang Antivenom

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Family Elapidae
Boulengerina annulata Ngwa maamba No antivenom
Dendroaspis polylepis Black mamba
Dendroaspis jamesoni Green mamba

• Flaccid paralysis and local necrosis
• Our Antivenom works for 3 of 5

Naja nigricollis Black-necked spitting
cobra Ophthalmia Different antivenom
Naja melanoleuca Black cobra
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Family Viperidae
Atheris nitschei Bush viper No antivenom
Bitis arietans Puff adder
Bitis gabonica Gaboon adder
Bitis nasicornis Rhinoceros viper Antivenom may
work

• Coagulaopthy, shock, renal damage,
  cardiotoxicity, local necrosis,
• neurotoxicity
• Our antivenom for 3 of 4

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Clinical effects

• Possible serious syndromes from envenomation
• Neurotoxicity
• Systemic toxicity including hypotension and shock
• Coagulopathy
• Rhabdomyolysis
• Renal failure
• Local tissue necrosis including cobra spit

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Neurotoxicity

• Neurotoxins block transmission at the NM junction
• Flaccid/Respiratory paralysis
• Anticholinesterase drugs
• Unphysiologic drowsiness

13
Hypotension/shock

• Vasodilation
• Direct action of venom on myocardium
• Bleeding/hypovolemia
• Vipers profound hypotension within minutes (ACE
  inhibitors)

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Coagulopathy

• Procoagulants and anticoagulants
• Intravascular coagulation, consumption
  coagulopahty
• Thrombocytopenia
• Bleeding from old and recent wounds, gingiva,
  epistaxis, hematemesis, melena

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Renal failure/rhabdomyolysis

• ATN hypotension/hypovolemia, DIC, direct toxic
  effect on tubules, hemoglobinuria, myoglobinuria
• Generalized rhabdo Release of myoglobin, muscle
  enzymes, uric acid, K (presynaptic neurotoxins)

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Local necrosis

• Increased vascular permeability
• Swelling and brusing
• Myotoxins and cytotoxins
• Ischemia/ thrombosis
• Venom ophthalmia

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Snake Bite Protocol
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Field Management

• Remove victim from snake area
• Place patient at rest and reassure
• Cleanse wound
• Immobilize the affected part of the body
• Attempt to identify snake without endangering
  anyone
• Transport patient to nearest medical facility
• Do NOT use pressure immobilization unless mamba
  55mmHg
• Do NOT do incision or suction or surgery. Can do
  worse damage

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Treatment

• Consider Antivenom immediately if
• Elapidae Dendroaspis jamesoni - green mamba
• Elapidae Dendroaspis polylepis - black mamba
• Elapidae Naja melanoleuca - black cobra
• Viperidae Bitis arietans - puff adder
• Viperidae Bitis gabonica - Gaboon Viper
• Viperidae Bitis nasicornis - Rhinoceros Viper OR
• Severe symptoms
• Supportive care for specific syndromes

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Initial Hospital Management

• Place patient at rest and reassure the patient
• Immobilize affected part of body
• Clean wound
• Give tetanus toxoid
• Try to identify type of snake website, list of
  snakes, picture book
• If snake one of six covered by antivenom,
  consider antivenom
• Have patient give urine

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Clinical Assessment

• Neurotoxicity Weakness? Flaccid paralysis?
  Ptosis? Dysarthria? Impaired swallow? Respiratory
  distress?
• Shock hypotension? Tachycardia? Altered mental
  status?
• Coagulopathy Bleeding? Epistasis? Petechiae?
  Bruising? Clotting?
• Rhabdomyolysis Muscle pain? Weakness? Dark
  urine?
• Renal failure Poor urine output? Edema?
• Local tissue necrosis fang marks, pain,
  swelling, bleeding, lymphadenitis, black skin?
  Tense skin?
• Non-specific systematic nausea, abdominal pain

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Laboratory assessment

• Neurotoxicity none
• Shock none
• Coagulopathy CBC, whole blood clotting test,
  INR, PTT, peripheral blood smear looking for
  schistocytes
• Rhabdomyolysis urine dipstick, urine sediment
• Renal failure creatinine
• Local tissue necrosis none
• Non-specific systematic none

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Neurotoxicity

• Consider Antivenom
• Serial exams Weakness? Flaccid paralysis?
  Ptosis? Dysarthria? Impaired swallow? Respiratory
  distress?
• Assisted ventilation if respiratory distress
• Consider anticholinesterase neostigmine 50-100
  mcg/kg

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Shock BPlt8/4 or pulsegt110

• Consider antivenom
• IV fluids Bolus iv fluids, Normal Saline or
  Ringer, to maintain blood pressure gt 10/6. Start
  with at least one liter.
• Monitor urine output, goal gt 30cc/hr (foley
  catheter)
• If actively bleeding, consider transfusion
• Consider dopamine if blood pressure low with
  fluids

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Coagulopathy

• Consider antivenom. Increase dose if continued
  bleeding.
• Transfuse whole blood only if life-threatening
  hemorrhage
• Monitor for signs of bleeding, and labs CBC,
  whole blood clotting test, INR, PTT, peripheral
  blood smear looking for schistocytes

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Rhabdomyolysis

• Consider Antivenom
• IV fluids Bolus with normal saline, 1-2 liters
  per hour. Urine output goal 200-300 cc/hr until
  urine clears
• Monitor potassium. If gt5.5, treat hyperkalemia
  (lasix and/or kayexalate and/or insulin).
• Monitor creatinine. If abnormal, see renal
  failure box.
• Avoid medications that are toxic to the kidney

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Renal failure

• Consider Antivenom
• IV bolus normal saline or Ringer, goal urine
  outputgt50cc/hr
• Monitor potassium. If gt5.5, treat hyperkalemia
  (lasix and/or kayexalate and/or insulin).
• Monitor creatinine
• Avoid medications that are toxic to the kidney

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Local tissue necrosis

• Consider antivenom
• Wound care keep site clean
• Monitor for compartment syndrome (decreased
  pulse, severe pain or lack of sensation)
  consider fasciotomy
• (cobras and vipers)
• Special case cobra spit ophthalmia irrigate eye
  with copious water or saline. Apply antibiotic
  ointment

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Nonspecific symptoms

• Treat nausea metoclopramide, phenergan
• Treat pain paracetamol, morphine. Avoid
  ibuprophen and diclofenac if bleeding.

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Antivenom Protocol
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Antivenom
Black cobra
Green mamba
Black mamba
Puff adder
Gaboon adder
Rhinoceros viper
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Antivenom

• Can cause severe allergic reactions
• Give it if
• can confirm that snake is covered by the
  antivenom OR
• Patient is severely ill and is not responding to
  supportive care

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Antivenom

• Antivenom Code SAfSAI03
• Antivenom Name SAIMR Polyvalent Antivenom
• Manufacturer South African Vaccine Producers
  (Pty) Ltd
• Tel [phone] , Fax[phone]
• Email cillaf_at_savp.co.za
• Homepage www.savp.co.za/default.htm

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Antivenom

• Prepare adrenaline 0.5 1 ml 0.1 sc
• Give antivenom. See package for details.
• Reassess whether need increased dose based on
• Clinical assessment
• Whole blood clotting test
• Reasons for failure insufficient antivenom,
  wrong antivenom, inactive antivenom, delay in
  administration
• Continue supportive care

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Antivenom

• Monitor for acute reactions
• Hypotension
• Urticaria
• Wheeze
• If present, give
• hydrocortisone 100 mg iv
• Adrenaline 0.3 ml sc if wheeze or hypotension

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Snake Bite Protocol
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Useful resources/Citations

• Snake picture book Dr Corrados office
• Pictures of snakeswww.afpmb.org
• Database of snake distributions and clinical
  manifestions www.toxinology.com
• List of antivenoms and suppliers
  http//toxinfo.org/antivenoms
• Poison information center (from WHO)
  www.who.int/ipcs/poisons/centre/directory/en/
• Cheng, Allen C. Principles of snake bite
  management worldwide UptoDate. June 2, 2008.

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Murakoze!