Snake bite

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Snake bite & envenomation : 

Snake bite & envenomation Dr.V.N.ALAGAVENKATESAN M.D

Background : 

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)

Background : 

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 >20 components Most Elapidae (mamba) deaths: hours Viper (puff adder) deaths: days

Family: Atractaspididae : 

Family: Atractaspididae Atractaspis irregularis (Variable Burrowing Asp) Indirect cardiotoxins, local necrosis No antivenom

Family: Boidae : 

Family: Boidae Python sebae (African rock python) No venom, do constrict victims – or even swallow! No antivenom

Family: Colubridae : 

Family: Colubridae Dispholidus typus (Boomslang) Toxicodryas blandingii (Blanding's Tree Snake) Coagulopathy and hemorrhaage SAIMR Boomslang Antivenom Postsynaptic neurotoxin, anticholinesterase No antivenom

Family: Elapidae : 

Family: Elapidae Boulengerina annulata Ngwa maamba No antivenom Dendroaspis jamesoni Green mamba Dendroaspis polylepis Black mamba Naja melanoleuca Black cobra Naja nigricollis Black-necked spitting cobra Ophthalmia Different antivenom Flaccid paralysis and local necrosis Our Antivenom works for 3 of 5

Family: Viperidae : 

Family: Viperidae Atheris nitschei Bush viper No antivenom Coagulaopthy, shock, renal damage, cardiotoxicity, local necrosis, neurotoxicity Our antivenom for 3 of 4 Bitis arietans Puff adder Bitis gabonica Gaboon adder Bitis nasicornis Rhinoceros viper Antivenom may work

Clinical effects : 

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

Neurotoxicity : 

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

Hypotension/shock : 

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

Coagulopathy : 

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

Renal failure/rhabdomyolysis : 

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)

Local necrosis : 

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

Field Management : 

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

Treatment : 

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

Initial Hospital Management : 

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

Clinical Assessment : 

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

Laboratory assessment : 

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

Neurotoxicity : 

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

Shock: BP<80/40 or pulse>110 : 

Shock: BP<80/40 or pulse>110 Consider antivenom IV fluids: Bolus iv fluids, Normal Saline or Ringer, to maintain blood pressure > 100/60. Start with at least one liter. Monitor urine output, goal > 30cc/hr (foley catheter) If actively bleeding, consider transfusion Consider dopamine if blood pressure low with fluids

Coagulopathy : 

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

Rhabdomyolysis : 

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 >5.5, 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

Renal failure : 

Renal failure Consider Antivenom IV bolus: normal saline or Ringer, goal urine output>50cc/hr Monitor potassium. If >5.5, treat hyperkalemia (lasix and/or kayexalate and/or insulin). Monitor creatinine Avoid medications that are toxic to the kidney

Local tissue necrosis : 

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

Nonspecific symptoms : 

Nonspecific symptoms Treat nausea: metoclopramide, phenergan Treat pain: paracetamol, morphine. Avoid ibuprophen and diclofenac if bleeding.

Antivenom : 

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

Antivenom : 

Antivenom Antivenom Code: SAfSAI03 Antivenom Name: SAIMR Polyvalent Antivenom Manufacturer: South African Vaccine Producers (Pty) Ltd Tel: +27-11-531-8600 , Fax:+27-11-531-8616 Email: Homepage:

Antivenom : 

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

Antivenom : 

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

Slide 31: 

Green mamba Black mamba Black cobra Puff adder Gaboon adder Rhinoceros viper THANK YOU

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