Snake bites (1).ppt
- 1. Identification of Snakes & Management of Snake Bites in Field Capt N S ROY OIC Section Hosp Pooh
- 3. FACTS : Snake Bite • Epidemiology – Rural: urban ratio ---- 9:1 – Monsoon and post monsoon, floods – Young active peoples • A major medical concern • Every one minute one person is bitten by a snake • Every two hours one person dies • Over four lakhs persons bitten by snakes every yr • Envenomation in 82,000 • Death occurs in 11,000
- 4. • All snakebite patients do not develop clinical symptoms and signs of envenomation • Snakes sometimes bite without injecting venom or inject too little venom to cause damage : Dry bite • Late onset envenomation---hard tissue /juvenile snakes FACTS : Snake Bite
- 5. • Site of action of venom varies from one snake to another • Complications due to snake bite may also vary from individual to individual • However, one has to observe for signs and symptoms which may develop within 24 to 48 hours FACTS : Snake Bite
- 6. • Status of poisoning can’t be judged by – Bite mark – Local reaction – Size of the snake
- 7. Poisonous Snakes of Indian sub continent Elapidae Short permt erect fangs Viperidae Long foldable fangs Cobras Kraits Coral Snakes Hydrophilidae Pit Vipers Typical Vipers Sea Snakes
- 8. Indian Cobra (Naja naja) • Highly venomous snake • Inflict the most snake bites in India • This snake is revered in Indian mythology • Now protected in India under the Indian Wildlife Protection Act(1972)
- 9. Indian Cobra (Naja naja) • Top 10 deadly snakes of the world • Found in rice fields • Milk not at all a food • Eats mole rats • Raise their head and spread their hood in defense • Binoculed mark
- 10. KRAIT • 3rd in top10 deadly snakes of the world • Rice fields/rubbles/piles of bricks/rat burrows/near human dwellings • Nocturnal • Black/white belly/paired white bands • Found only in Asia • 5 times more deadly than the common cobra • Late clinical features and late recovery
- 11. Common krait (Bungarus caeruleus) : paired white lines on body Banded krait (Bungarus fasciatus) : white/yellow & dark bands on body • Venom is more toxic than that of a cobra • The snake often enters people’s houses in its quest to find a cool place • People get bitten when they step on the snake accidentally
- 12. Russell’s Viper • Black edged chain-like marks & white ‘V’ on head • Stout body upto 1.8 mtr • Bushes of boundaries/ under the tree • Nocturnal like other vipers • It is irritable • When threatened, it coils tightly, hisses, and strikes with great speed
- 13. Saw Scaled Viper – Prefers deserts / dry scrubby area – White loop marks along body – Arrow mark / bird’s footmark on head – It may inject as much as 12 mg – Lethal dose for an adult is estimated to be only 5 mg
- 14. Hump Nosed Viper • One of the tiniest venomous snakes of India • Upto 30 cm • The snout is pointed and turned upwards, ending in a hump • Not responding to ASV • Coagulopathy upto 3 wks
- 15. Recognition of poisonous snakes Fangs
- 16. Recognition of poisonous snakes.. Head Russell’s Viper
- 17. Recognition of poisonous snakes.. Pupils
- 18. Recognition of poisonous snakes.. Belly scales
- 19. Recognition of poisonous snakes.. Body design Cobra
- 20. Russell’s viper
- 21. Saw-scaled viper
- 22. Banded Krait
- 24. Snake Venom Common components Procoagulant enzymes Haemolytic toxins Cytolytic / necrotic toxins Myolytic toxin Presynaptic neurotoxin Postsynaptic neurotoxin
- 25. Snake venoms : Symptoms Cobra Krait Russells Viper Hump nose viper Local effect ++ - +++ - Vasculotoxic - - +++ - Neurotoxic +++ +++ - - Myotoxic - - - +++ ASV response Yes Yes Yes No
- 26. Clinical Features Dry bites 20% pit viper bite, 43% cobra bites Local features Fang marks Pain Swelling Blistering & necrosis Lymphangitis, lymphadenopathy Secondary infection Venom ophthalmia
- 27. Local effect of pit-viper bite
- 28. Local effect of a viper bite
- 29. General features flushing,sweating, breathlessness, palpitation,tightness in chest,nausea, vomiting ( in all severe envenoming) acroparaesthesiae, hyper salivation, blurring of vision (cobra) abdominal colic, diarrhoea, collapse ( krait)
- 30. Systemic Features – Cobra / Krait bite Neurotoxicity • onset as early as 15 min with ptosis & external ophthalmo-plegia • Rapid descending paralysis • Life threatening respiratory paralysis • Effects completely reversible with antivenom / anticholinesterases • spontaneously wear off in 1 – 7 days Cardiotoxicity • direct myocardial toxicity
- 31. Systemic Features – Viper bite • Clotting defect & haemolysis • Persistent bleeding from puncture sites • Epistaxis • Spontaneous systemic bleeding (gingival sulci commonest site) • Hypotension • Lymph Node enlargement Nephrotoxicity Cause - hypovolemia & ischaemia
- 32. Late onset envenomation • The patient should be kept under close observation for at least 24 hours • Krait and the Hump-nosed viper are known for the length of time it can take • Late onset envenoming is a well documented occurrence • Juvenile snake bite
- 33. CRITERIA FOR DIAGNOSIS OF COMPLICATIONS • Local envenomation – Swelling of limb – Lymphadenopathy • Systemic envenomation – Bleeding diathesis – Neurotoxicity – Renal failure
- 34. Management • Treatment at site • Transportation to nearest medical facility • Treatment at medical facility
- 35. First Aid : RIGHT • Reassure the patient – 70% of all snakebites are from non-venomous – Only 50% of bites by venomous species actually envenomate the patient
- 36. • Immobilize the bitten limb in the same way as a with fractured limb • Use bandages or cloth to hold the splints, not to block the blood supply or apply pressure • Do not apply any kind of compression in the form of tight ligatures, they don’t work and can be dangerous
- 37. • G. H. = Get to Hospital Immediately • Traditional remedies have NO proven benefit in treating snakebite • T = Tell the doctor of any systemic symptoms of the patient such as ptosis that manifest on the way to hospital
- 38. Diagnosis Phase: General Principles • Where possible identify the snake responsible • All patients will be kept under observation for a minimum of 24 hours • In India bite marks are of no use in identifying if a species is venomous or not • Many non venomous species leave just two fang-like marks e.g. Wolf Snakes • Some species like the Krait may leave no bite mark at all • Many venomous species have more than two fangs, as they grow reserve fangs in case the main ones break off
- 39. • Determine if any traditional medicines have been used, they can sometimes cause confusing symptoms • Determine the exact time of the bite. This can give indications as to the progression of any symptoms • Ask questions as to what the victim was doing at the time of the bite • Some activities such as grass cutting or feeding stock animals in the evening can be suggestive of snakebite
- 40. Pain Management • Snakebite can often cause severe pain at the bite site • This can be treated with painkillers such as paracetamol, 4-6 hourly orally • Aspirin should not be used due to its adverse impact on coagulation • Tramadol, 50 mg can be used orally • In cases of severe pain at a tertiary centre, Tramadol can be given IV
- 41. 20 Minute Whole Blood Clotting Test (20WBCT) • Considered the most reliable test of coagulation • Can be carried out at the bedside without specialist training • It can also be carried out in the most basic settings • It is significantly superior to the ‘capillary tube’ method of establishing clotting capability • Preferred method of choice in snakebite
- 42. • A few ml of fresh venous blood is placed in a new, clean and dry glass test tube and left at ambient temperature for 20 minutes • The glass vessel should be left undisturbed for 20 minutes and then gently tilted, not shaken • If the blood is still liquid then the patient has incoagulable blood
- 43. • The test should be carried out every 30 minutes from admission for three hours and then hourly after that • If incoagulable blood is discovered, then 6 hourly cycle will be adopted to test for the requirement for repeat doses of ASV
- 44. Tourniquets • The use of tight tourniquets made of rope, belt, string or cloth have been traditionally used to stop venom flow into the body following snakebite • Tourniquets do not work and have the following problems: – Risk of Ischemia and loss of the limb – Increased Risk of Necrosis – Increased risk of massive neurotoxic blockade when tourniquet is released – Pro-coagulant enzymes will cause clotting in distal blood – The effect of the venom in causing vasodilatation presents the danger of massive hypotension when the tourniquet is released
- 45. • Venom was not slowed by the tourniquet in several experimental studies, as well as in field conditions • Often this is because they are tied on the lower limb or are incorrectly tied • They give patients a false sense of security, which encourages them to delay their journey to hospital
- 46. Cutting and Suction • Cutting a victim with in-coagulable blood increases the risk of severe bleeding as the clotting mechanism is no longer effective • Increases the risk of infection • No venom is removed by this method • Suction devices have been conclusively proven not to reduce the amount of circulating venom • There has been some evidence that these devices increase envenomation as they inhibit natural oozing of venom from the wound • They have been shown to increase the local effects of necrosis
- 47. • Washing the Wound – Victims and bystanders often want to wash the wound to remove any venom on the surface – This should not be done as the action of washing increases the flow of venom into the system by stimulating the lymphatic system • Electrical Therapy – The theory behind electrical shock therapy is that an electric current to the wound denatures the venom – However, research shows that the venom is not denatured at all • Cryotherapy – Cryotherapy involves the application of ice – It has been shown that this method had no benefit and merely increased the necrotic effect of the venom
- 48. INDICATIONS OF ASV • Definite signs of envenomation – Evidence of coagulopathy – Evidence of neurotoxicity – Cardiovascular abnormalities – hypotension, shock, abnormal ECG • Severe local envenomation – More than half of bitten limb
- 49. PRINCIPLES IN ASV ADMINISTRATION • Russells Viper injects on an average 63mg of venom(range 5mg – 147mg) • Each vial of ASV neutralizes 6mg of Viper venom • 10 vials is adequate to neutralize the average amount of venom • 30 vials will neutralize the maximum venom
- 50. ASV • NO ASV TEST DOSE MUST BE ADMINISTERED • Complement mediated • May sensitize patient
- 51. Dosages • Neurotoxic/ Anti Haemostatic 8-10 Vials Administration • Intravenous Injection: reconstituted or liquid ASV is administered by slow intravenous injection. (2ml/min) • Infusion: liquid or reconstituted ASV is diluted in 5-10ml/kg in isotonic saline/glucose
- 52. ASV reactions • Develop within 15 – 30 mins or within 2 hrs • Itching, urticaria, nausea, vomitting, abdominal colic, hypotension, bronchospasm, angioedema of lips, fever, rigors, sweating, cyanosis Treatment: • Discontinue ASV • Inj. Adrenaline 0.5 ml of 1:1000 • If no improvement after 10-15 mins 2nd dose of 0.5 ml of Adrenaline to be given • Can be repeated for a third and final occasion
- 53. Evaluation in hospital • look for fang marks • monitor vitals, local swelling & muscle weakness hourly • look for bleeding • platelet count 12 h • 20 min BTCT, PT 6h • serum electrolytes 6 h • LFT, RFT, CPK, ECG daily • monitor urine output, myoglobinuria
- 54. Management at Hospital • Rapid assessment • Clinical evaluation & species Dx • Investigation/laboratory test • Antivenom treatment • Supportive/ancillary treatment • Treatment of local part • Treatment of complication
- 55. Supportive therapy • Tetanus prophylaxis • Antibiotics in severe local envenoming • Fasciotomy for compartment syndrome • Respiratory paralysis managed with assisted vent, neostigmine & atropine • FFP, cryoprecipitates & platelet concentrate for haemostatic disturbances
- 56. PREVENTIVE MEASURES • Camp Sanitation • Anti rodent measures • Trench Discipline – 50cm wide x 60 cm deep, spray with K oil +Engine oil + 0.5% Carbolic acid • Personal protection – mosquito net, anklets, boots, Torches • Training in First aid
- 57. Discussion