Kamis, 11 Agustus 2011

Snake Bites Types,Diagnosis and Management-Medical Lecture Note

            3500   Species
            300     Venomous
            30000 - 40000 Death annually
  o   India
  o   Brazil
  o   Buruma

Poisonous Snakes
5 families
  1. Crotalidae-rattle snake,pit viper

  2. Viperidae-russel’s ,sawscaled viper

  3. Elapidae-cobra,krait

  4. Hydrophiodae-sea snake

  5. Colabridae 

    Indian scenario
    5 dangerously poisonous snakes
    ·         king cobra
    ·         common cobra
    ·         common krait
    ·         russell’s viper
    ·         sawscaled viper

    Most common poisonous snake is common krait
    ·         216  species
    ·         52  venomous
    ·         Ireland
    ·         Newzealand

    Snake venom
    ·         Toxic saliva secreted by modified parotid glands of a venomous snake
    ·         Amber coloured when fresh
    ·         Toxins
    ·         Enzymes
    ·         Neurotoxins
    ·         Cardiotoxins
    ·         Hemolysin

    Venom apparatus


    Venom classification
    ·         Neurotoxic-Elapids(cobra,krait)
    ·         Hemotoxic-Viperidae
    ·         Myotoxic-Sea snake

    Krait and russell’s viper is much more toxic than that of cobra
    Symptomatology of non venomous snakes
    ·         Universal fear associated induce a state of shock
    ·         Bite site may demonstrate multiple teeth impressions
    ·         Lack of significant local pain or swelling
    ·         Adequate reassurance and symptomatic treatment measures lead to full recovery

    Symptomatology of venomous snakes
    1.       Elapid bite
    Local features:
    ·         Indistinct fang marks ,
    ·         Burning pain,
    ·         Swelling and discolouration,                                                                         
    ·         Serosanguinous discharge
    Systemic features
    ·         Preparalytic stage: Emesis,headache, LOC.
    ·         Paralytic stage: ptosis,ophthalmoplegia drowsiness,dysarthria, dysphagia,convulsions, bulbar paralysis, resp failure .

    2.       Viperid bite
    Local features:
    ·         Rapid swelling,
    ·         Discolouration,
    ·         Blister formation,
    ·         Bleeding from bite site,
    ·         Severe pain
    Generalised bleeding manifestations.                       
    • epistaxis,

    • hemoptysis,

    • bleeding gums

    • hemauria

    • purpuric spots

    • Renal failure

    Hydrophid bite
    Local features:
    §  minimal swelling and pain
    Systemic features:
    §  Myalgia muscle stiffness
    §  Myoglobinuria ,
    §  Renal tubular
    §  Necrosis                  

    Diagnosis of snake bite
    1.       Fang marks:classically, two puncture wounds seperated by a distance varying from 8mm to 4cm, depending on the species involved.
    2.       However a side swipe may produce only a single puncture,while multiple bites could result in numerous fang marks.
    3.       Bailey’s method
    Identification  of snake
    §  Poisonous  or non poisonous
    §  Species
           Venomous                  Non venomous

    Stout, dull coloured             abruptly tapering tail
    Slender,brightly coloured gradually tapering tail
    Tail: may be rounded or flattened
    Always rounded
    Belly scales are broad
    Belly scales are small..do not extend the entire width
    Head :triangular
    Rounded or oval
    Head scales: usually small
    Usually large (shields)
    At least one pair of teeth in the upper jaw are modified to form fangs
    All teeth are uniformly small in size
    Saliva contains toxic peptides and enzymes
    Non toxic

    Non-venomous snakes


    Red Sand Boa
    Eryx conicus (chenathandan)


    Bronze back tree snake

    Ckeckered keelback

    Striped keelback

    Cat Snak

    The Venomous snakes

    Banded  krait

    Hook nosed sea snake

    Pit viper

    Saw Scaled viper

    Slender coral snake
    Management of snake bite
    1.       First aid treatment
    2.       Transport to hospital
    3.       Rapid clinical assessment and resuscitation
    4.       Investigations/laboratory tests
    5.       Antivenom treatment
    6.       Supportive/ancillary treatment
    7.       Treatment of the bitten part
    8.       Rehabilitation
    9.       Treatment of chronic complications

    First aid
    §  Delay enry of venom
    §  Tourniquet
    §  Above knee
    §  Above elbow

    Useless or Dangerous Methods
    §  Making local incisions or pricks at the site of the bite or in the bitten limb
    §  Attempts to suck the venom out of the wound
    §  Use of snake stones
    §  Electric shock
    §  Topical instillation or application of chemicals, herbs or ice packs.

    Clinical assesment
    Vital signs
    o   pulse
    o   BP
    o   Respiration –SBC

    o   Bite mark
    o   Local reaction
    o   Painful INE
    o   Ptosis
    o   Ophthalmoplegia
    o   Myasthenia like symptoms
    o   Asses SBC
    o   Purpura
    o   Echymosis
    o   Gingival sulcus bleed
    o   Hematuria
    Capillary leak syndrome
    o   Puffiness
    o   Chemosis
    o   Parotid swelling

    Lab. Investigations
    o   Leucocytosis(>20,000-severe envenomation)                          
    o   Elevated PCV
    o   Thrombocytopenia
    o   Evidence of hemolysis
    o   Prolonged ct,pt,ptt
    o   Elevated fdp
    Ct     >    20 minutes
    Sure sign of envonomation
    Pitviper   > 2 weeks
    ECG: bradycardia
                 ST-Elevation or other way
                 T-wave inversion
                 QT Prolongation
                 Changes due to hyperkalemia
             Hypoxemia with resp.ac
             Met.ac or lactic ac
    Renal : ARF -- BU S.Cr   S E
    CXR :  Pulm.edema
               Pleural effusion
    Immuno-diagnosis: by ELISA….
    Highly sensitive but specificity inadequate to diff b/w diff species of snakes
    Specific management  asv
    Horse serum
    Asv in india
    o   cobra
    o   krait
    o   russel’s viper
    o   saw scaled viper

    1 mi ASV     -   0.6mg cobra R viper
                        -   0.45mg krait S viper
    Indication -Systemic Manifestaiton
    o   Neurotoxicity
    o   Repeated vomiting
    o   Haemotoxicity
    o   Nephrotoxicity
    o   Cardiotoxicity
    o   Rhabdomyolysis

    Prolonged CT  alone
    o   Pit viper  -  no
    o   Snake not identified

    Neurotoxic envonomation
    o   Initial dose  10  -  15 vials
    o   Reassess
    o   Improvement   30  --  60 min
    o   Repeat  5 vials after 60  -- 90 mins
    o   Supportive – neostigmine after atropine

    Haemotoxic envonomation
    Mild            CT < 30 mins
                       Clot size = 50% blood col
                       Initial dose = 5 vials
    Moderate   CT   > 30 mins
                       Clots only speckles
                       initial dose   = 10 vials
    Severe      incoagulable
                     Initial dose  = 15 vials
    Repeat ct after 6 – 9 hours
    If ct pronged repeat 5- 10 vials
    Low dose infusion – following days
    Supportive care
    o   Antibiotics
    o   Methyl prednisolone
    o   FFP, fresh blood
    o   Prevention and rx of hypotension
    o   prevention of shock
    Prevention of arf
    ·         Proper fluid administration
    ·         Correct myocardial dysfunction
    ·         Monitor output bu s.cr se                
    ·         Avoid  nephrotoxic drugs
    ·         Protein restriction

    Management of local reactions
    ·         Bullae   - left intact
    ·         Necrosis  - debridement
    ·         Compartment syndrome – fasciotomy
    ·         Most comfortable position

    Reactions to anti venom
    ·         Anaphylactoid 10 – 90 mins
    ·         Pyrogenic 2 hours
    ·         Serum sickness 5 – 21 days

    Bee and wasp sting
    ·         Neurotoxic
    ·         Hemolytic
    ·         Hypersenstising agents - anaph
    ·         Rx  local antihistamines

    Scorpion sting
    ·         Hemo / neuro toxic
    ·         Sting mark one hole in centre
    ·         Take ecg to r o cardiotoxicity
    ·         Rx local anaesthetic ice pack

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