Snake bite basics in a visually appealing format for general population, school and college students, medical students, paramedics, nurses, and pg residents. Snakes included only pertaining to indian subcontinent. Any medical data given is valid only for indian subcontinent.

1. Snake Bites
Maj Mayank Jain
333 Field Hospital

2. Global distribution of dangerously
venomous snakes

3. It has been reported that there
are 5 million snake bites in the
world every year...

4. Resulting in 2.5 million
envenomings..

5. 125,000 deaths and many more
of permanent sequelae.

6. In India alone there may be as
many as 50,000 snake bite
deaths each year

7. Who is at risk ?
Snake-bite is an
occupational
hazard of soldiers,
farmers, plantation
workers, etc.

8. Identification of
poisonous snakes

9. Echis carinatus
The ‘Big 4’ in India
Naja naja Daboia russelii
Bungarus caeruleus

10. Poisonous Non Poisonous
1. Large belly
scales covering the
entire width of
belly are always
poisonous.

11. Poisonous
2. Head Scales are usually small in vipers, maybe large in pit
vipers. In Cobras and Coral Snakes third labial touches eye
and nasal shield. In Kraits there is no head pit and third labial
does not touch nose and eye.
NON POISONOUS - Usually large head scales, except in above.

12. Poisonous Non Poisonous
3. Large hollow
fangs, prominent in
front are poisonous

13. Short, permanently
erect, front fangs of a
typical elapid
Long, hinged, front
fangs of a typical viper

14. Poisonous Non Poisonous
4. Two fang marks with
or without smaller teeth
are poisonous

15. Prevention

16. Overhanging tree
branches serve as a
conduit for snakes.
Cracks and holes in
masonry is where
snakes lurk in plenty.
Using a mosquito net
can prevent snakes
falling from roof
directly on a person.

17. Snakes feast on frogs
and rodents.
Water bodies harbor
frogs which in turn
attract snakes.
Piles of rubble lying
undisturbed are liable
to harbor snakes.

18. Use a torch when
going outdoors at
night.
Wear high ankle boots
while on exercise.
Do not go out without
proper footwear in a
camp.

19. Sarpgandha (Rauvolfia serpentina)
Snake repellent plants

20. Chirota (Andrographis peniculata)
Snake repellent plants

21. Signs & Symptoms

22. Either because of mechanical inefficiency or the snake’s control of
venom discharge, a proportion of bites by venomous snakes does not
result in the injection of sufficient venom to cause clinical effects.
Dry Bites

23. Rapid primary clinical assessment and resuscitation:
ABCDE approach
● Airway
● Breathing (respiratory movements)
● Circulation (arterial pulse)
● Disability of the nervous system (level of consciousness)
● Exposure and environmental control (protect from cold, risk of drowning
etc.)

24. Early clues that a patient has severe envenoming:
● Snake identified as a very dangerous one.
● Rapid early extension of local swelling from the site of the bite.
● Early tender enlargement of local lymph nodes, indicating spread of venom in the lymphatic
system.
● Early systemic symptoms: collapse (hypotension, shock), nausea, vomiting, diarrhoea, severe
headache, “heaviness” of the eyelids, inappropriate (pathological) drowsiness or early
ptosis/ophthalmoplegia.
● Early spontaneous systemic bleeding.
● Passage of dark brown/black urine.

25. Local signs of envenoming
Fang marks
Blistering
Persistent local bleeding

26. Manifestations of neurotoxicity

27. External ophthalmoplegia and ptosis

28. ___________ Neck Sign ?

29. Broken Neck Sign

30. Do not assume that snake
bitten patients are unconscious
or even irreversible
“brain dead”
just because their eyes are
closed, they are
unresponsive to painful stimuli,
are areflexic, or have fixed
dilated pupils.
They may just be paralysed!

31. Manifestations of hemolysis

32. Hemorrhage from gingival sulci

33. Hemoptysis Cutaneous discoid hemorrhages

34. Conjunctival chemosis
and hemmorrhage

35. ?

36. Myoglobinuria

37. Sequelae

38. Life threatening total flaccid paralysis
requiring assisted ventilation

39. Fatal cerebral hemorrhage

40. Hypertrophic scar following cobra bite

41. Malignant transformation (Marjolin’s
ulcer) in a chronic snake bite ulcer

42. Tissue necrosis

43. Evaluation

44. 20 Minute Whole Blood Clotting Test

45. 20-minute whole blood clotting test
● If the blood is still liquid (unclotted) and runs out, the patient has hypofibrinogenaemia
(“incoagulable blood”) as a result of venom-induced consumption coagulopathy.
● In the South-East Asia region, incoagulable blood is diagnostic of a viper bite
and rules out an elapid bite.
● If the vessel used for the test is not made of ordinary glass, or if it has been cleaned with
detergent, its wall may not stimulate clotting of the blood sample (surface activation of factor XI
– Hageman factor) and test will be invalid If there is any doubt, repeat the test in duplicate,
including a “control” (blood from a healthy person such as a relative)

46. Other tests
● WBC Count - An early neutrophil leucocytosis is evidence of systemic envenoming.
● Platelet count - May be decreased.
● PBS - Helmet cells/Schistocytes
● Plasma - discolored due to hemoglobinemia/myoglobinemia
● ABG - eveidence of respi failure.
● Biochemistry - generalized muscle damage picture, renal failure, raised liver enzymes
● Urine - immunoassays can separate hemoglobin and myoglobin

47. Treatment

48. Antivenom is the only effective
antidote for snake venom.

49. Most ‘traditional’ methods do
more harm than good.

50. Remove the patient from
the snake's territory, and
keep him or her warm,
at rest, and calm.

51. Immobilize the limb in a
functional position and avoid
undue movements.

52. Antivenom should be given only
to patients in whom its benefits
are considered likely to exceed its
risks. Since antivenom is
relatively costly and often in
limited supply, it should not be
used indiscriminately. The
risk of reactions should always be
taken into consideration.

53. Indications for antivenom
Antivenom treatment is recommended if and when a patient with proven or suspected snake-bite
develops one or more of the following signs:
● Systemic envenoming
● Haemostatic abnormalities: Spontaneous systemic bleeding (clinical), coagulopathy (20WBCT
or other laboratory tests such as prothrombin time) or thrombocytopenia (<100 x 109/litre or
100 000/cu mm) (laboratory).
● Neurotoxic signs: ptosis, external ophthalmoplegia, paralysis etc (clinical).
● Cardiovascular abnormalities: hypotension, shock, cardiac arrhythmia (clinical), abnormal
ECG.

54. Indications for antivenom
● Acute kidney injury (renal failure): oliguria/anuria (clinical), rising blood creatinine/ urea
(laboratory).
● (Haemoglobin-/myoglobin-uria:) dark brown urine (clinical), urine dipsticks, other evidence of
intravascular haemolysis or generalised rhabdomyolysis (muscle aches and pains,
hyperkalaemia) (clinical, laboratory).
● Supporting laboratory evidence of systemic envenoming (see above).

55. Indications for antivenom
● Local swelling involving more than half of the bitten limb (in the absence of a tourniquet) within
48 hours of the bite. Swelling after bites on the digits (toes and especially fingers).
● Rapid extension of swelling (for example, beyond the wrist or ankle within a few hours of bite on
the hands or feet).
● Development of an enlarged tender lymph node draining the bitten limb

56. ● 2 vials initial bolus
dose ?
● Infuse 5-10 vials in
NS/DNS (250-500
mL) over 1 hour
● Infuse at 2ml/min
● More vials
depending on
envenomation
● Sensitivity tests
NOT recommended
● No benefit of local
infiltration

57. Skin and conjunctival “hypersensitivity” tests will reveal IgE
mediated Type I hypersensitivity to horse or sheep proteins.
However, since the majority of early (anaphylactic) or late
(serum sickness type) antivenom reactions result from
direct complement activation rather than from IgEmediated
hypersensitivity, these tests are not predictive.
Since they may delay treatment and can in themselves be
sensitising, these tests should not be used !

58. At the earliest sign of a reaction:
● Antivenom administration must be temporarily suspended.
● Epinephrine (adrenaline) (0.1% solution, 1 in 1,000, 1 mg/ml) is the effective treatment for early
anaphylactic and pyrogenic antivenom reactions.

59. Snakes inject the same dose of venom into children and
adults.
Children must therefore be given exactly the same dose of
antivenom as adults.

60. ● Artificial ventilation
is necessary if
patient shows any
sign of paralysis
● A trial of
anticholinesterase
should be
performed in all
patients with
neurotoxic signs.
● Atropine sulfate, or
glycopyrronium
followed by
Neostigmine

61. Detection of kidney
injury:
• dwindling or no urine
output
• rising blood
urea/creatinine
concentrations
• clinical “uraemia
syndrome”

62. Thank You