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

Constituents              

·         Toxins

·         Enzymes

·         Neurotoxins

·         Cardiotoxins

·         Hemolysin

Venom apparatus

Fangs

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

Kurudan

Red Sand Boa

Eryx conicus (chenathandan)

Python

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

Observe

o   Bite mark

o   Local reaction

o   Painful INE

           

Neurotoxicity

o   Ptosis

o   Ophthalmoplegia

o   Myasthenia like symptoms

o   Asses SBC

Haemotoxicity

o   Purpura

o   Echymosis

o   Gingival sulcus bleed

o   Hematuria

Capillary leak syndrome

o   Puffiness

o   Chemosis

o   Parotid swelling

Lab. Investigations

Haematological

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

             

Metabolic

         Hyperkalemia

         Hypoxemia with resp.ac

         Met.ac or lactic ac

Urine

         Hematuria,proteinuria,Hburia

         Mburia

        

Renal : ARF -- BU S.Cr   S E

CXR :  Pulm.edema

           Intrapulm.hgs

           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