Snakebite is a medical emergency that can be life-threatening. It most commonly affects rural populations in tropical areas. There are many species of poisonous snakes in India, with the "Big Four" being cobras, kraits, Russell's vipers, and saw-scaled vipers. Snake venom causes local and systemic effects through neurotoxins and hematoxins. Proper first aid and timely administration of antivenom are important for treatment. Hospital management involves monitoring for signs of envenoming, administration of antivenom, and supportive care.
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Approach to a victim of snake bite
1. AN APPROACH TO A SNAKEAN APPROACH TO A SNAKE
BITE VICTIMBITE VICTIM
Dr. Soumar Dutta. MD. DEM. MEM
Consultant and Coordinator
Department of Emergency Medicine
Narayana Superspeciality Hospital, Guwahati
2. INTRODUCTIONINTRODUCTION
Snakebite is an acute life threatening time limitinglife threatening time limiting medical emergency
It is a preventablepreventable public health hazard often faced by rural populationrural population
in tropical and subtropical countries with heavy rainfall and humid climate.
2
3. SNAKE BITESNAKE BITE – AN OCCUPATIONAL DISEASE– AN OCCUPATIONAL DISEASE
FishermanWorkers at site
Farmers Snake Charmers Plantation work
Hunter
3
4. STATISTICSSTATISTICS
• There is a huge gap between the number of snakebite deaths reportedThere is a huge gap between the number of snakebite deaths reported
from direct survey and official data.from direct survey and official data.
• Only 7.23% snakebite deaths were officially reportedOnly 7.23% snakebite deaths were officially reported
Mohapatra,2011 Mazumdar,2014
49,500 deaths annually 5-6 lakhs bites annually but only 30% are
venomous bites
Mostly rural population Only 22.19% reaches hospital.
Common in males than females Delay in first aid and unavailability of
ASV
Andhra Pradesh, Bihar, Tamil Nadu,
West Bengal, Uttar Pradesh
Majority of the bites being on the lower
extremities
4
5. About 50% of bites are dry
Majority (80%) is by non-venomous snakesSnake bite
Venomous snakes
FACTSFACTS
5
6. Features of poisonous & non-poisonous snakesFeatures of poisonous & non-poisonous snakes
Non Poisonous SnakesNon Poisonous Snakes
Head - Rounded
Fangs - Not present
Pupils - Rounded
Anal Plate - Double row
Bite Mark - Row of small teeths
Poisonous SnakesPoisonous Snakes
Head - Triangle
Fangs - Present
Pupils - Elliptical pupil
Anal Plate - Single row
Bite Mark - Fang Mark
6
7. COMMON POISONOUS SNAKES IN INDIA
• In India, >200 species of snakes; only 52 are poisonous.
1. Saw-scaled viper (Echis carinatus)
2. Russell’s viper (Daboia russelii)
3. Common krait (Bungarus caeruleus)
4. Indian cobra (Naja naja)
Neurotoxic
20-30% of bites
Majority of bites 70-80%
Hemotoxin / Vasculotoxin
7
8. IS THERE ANY MEDICAL IMPLICATIONIS THERE ANY MEDICAL IMPLICATION
FOR SNAKE IDENTIFICATION?FOR SNAKE IDENTIFICATION?
8
9. SPECIES: MEDICAL IMPLICATIONS
Signs/Symptoms and
Potential Treatments
Cobra Krait
Russell’s
Viper Saw Scaled
Viper
Other Vipers
Local pain/ Tissue
Damage Yes No Yes Yes Yes
Ptosis/Neurotoxicity Yes Yes Yes! NO No
Coagulation No No Yes Yes Yes
Renal Problems No No Yes NO Yes
Neostigmine & Atropine
Yes No No NO No 9
12. HEMOTOXICITY
•Starts late hence most of them reach hospitals
•Many organ involvement hence MV is mostly
supportive to buy time for organs to recover.
•More number of cases.
NEUROTOXICITY
•Starts early- many die before they reach
hospitals
•Many reverse very well with ASV if started
early
•Less number of cases
70-80%
20-30%
Overlap:
Neuro-hemat
12
13. WHAT IS THE MODE OFWHAT IS THE MODE OF
NEUROTOXICITY IN KRAIT BITENEUROTOXICITY IN KRAIT BITE
13
14. Beta-bungarotoxin- Phospholipases A2
1) Inhibiting the release of Ach
from the presynaptic membrane
2) Presynaptic nerve terminals
exhibit signs of irreversible
physical damage and are devoid of
synaptic vesicles
3) ASV & anticholinesterases have
no effect
• Paralysis lasts several weeks and frequently requires prolonged MV.
• Recovery is dependent upon regeneration of the terminal axon.
KRAIT- PRE-SYNAPTIC ACTION
14
15. WHAT IS THE MODE OFWHAT IS THE MODE OF
NEUROTOXICITY IN COBRA BITENEUROTOXICITY IN COBRA BITE
15
16. COBRA – POST-SYNAPTIC
Alpha-neurotoxins “curare -mimetic toxins’’
•Bind specifically to Ach receptors, preventing the
interaction between Ach and receptors on postsynaptic
membrane.
•Prevents the opening of the sodium channel associated
with the Ach receptor and results in neuromuscular
blockade.
• ASV -rapid reversal of paralysis.
•Dissociation of the toxin-receptor complex, which leads to
a reversal of Paralysis
Anticholinesterases reverse the neuromuscular blockade
16
17. NEURO PARALYTIC MANIFESTATIONS STUDY
Ptosis
Repiratory Involvement
Bulbar weakness
N Sharma, S Chauhan, S Faruqi, P Bhat, S Varma, Emerg Med J 2005;22:118–120
OphthalmoplegiaOphthalmoplegia
17
19. NEUROTOXIC ENVENOMING EXAMINATION
• Ask the patient to look up and observe whether the
upper lids retract fully.
• Test eye movements for evidence of early external
ophthalmoplegia .
• Check the size and reaction of the pupils.
• The muscles flexing the neck may be paralyzed, giving
the “broken neck sign
19
21. NEUROTOXIC ENVENOMING-EXAMINATIONNEUROTOXIC ENVENOMING-EXAMINATION
• Krait can cause fixed, dilated non reactive pupils simulating brain stemKrait can cause fixed, dilated non reactive pupils simulating brain stem
death – however, it can recover fullydeath – however, it can recover fully
• Ask the patient to open their mouth wide and protrude their tongue; earlyAsk the patient to open their mouth wide and protrude their tongue; early
restriction often due to paralysis of pterygoid muscles.restriction often due to paralysis of pterygoid muscles.
21
22. HOW TO IDENTIFYHOW TO IDENTIFY
FORFOR
BULBAR PALSY & EARLYBULBAR PALSY & EARLY
RESPIRATORY FAILURERESPIRATORY FAILURE
22
23. BULBAR & RESPIRATORY PARALYSISBULBAR & RESPIRATORY PARALYSIS
• Impaired swallow or are secretions accumulating inImpaired swallow or are secretions accumulating in
the pharynx- an early sign of bulbar paralysis.the pharynx- an early sign of bulbar paralysis.
• Objective measurement of ventilatory capacity is very useful. Use a peakObjective measurement of ventilatory capacity is very useful. Use a peak
flow meter, spirometer (FEV1 and FVC)flow meter, spirometer (FEV1 and FVC)
• Ask the patient to blow into the tube of a sphygmomanometer to recordAsk the patient to blow into the tube of a sphygmomanometer to record
the maximum expiratory pressure (mmHg).the maximum expiratory pressure (mmHg).
23
24. PARADOXICAL RESPIRATIONPARADOXICAL RESPIRATION
• This is an abnormal pattern of breathing in which the abdominal wall isThis is an abnormal pattern of breathing in which the abdominal wall is
sucked in during inspiration (it is usually pushed out).sucked in during inspiration (it is usually pushed out).
• Due to paralysis of the diaphragm.Due to paralysis of the diaphragm.
24
25. HEMATOLOGICAL SIDE EFFECTS
• Venom induces bleeding.Venom induces bleeding.
• Venom induces clotting.Venom induces clotting.
• Venom induces haemolysis.Venom induces haemolysis.
• Haemorrhagin – causes direct endothelial damage by loosening theHaemorrhagin – causes direct endothelial damage by loosening the
gap between endothelial cells.gap between endothelial cells.
• Pro-coagulant factors.Pro-coagulant factors.
• Anticoagulant factors.Anticoagulant factors.
• Fibrinonolytic factors.Fibrinonolytic factors.
25
26. SNAKE VENOM AND THE COAGULATION CASCADESNAKE VENOM AND THE COAGULATION CASCADE
RVV – Russel’s Viper
Venom ECV – Echis
carinatus
Venom
28. 20 MIN WHOLE BLOOD CLOTTING TEST
• Take 2 ml fresh blood in glass vessel
• Leave undisturbed for 20 minutes
• If blood is still liquid – incoagulable blood – Hypofibrinogenaemia/DIC
• Repeat the test periodically if positive – Normal WBCT is 6-8 min
28
29. LOCAL SYMPTOMS & SIGNS IN THE BITTEN PART
• Fang marks
• Local pain
• Local bleeding
• Bruising
• Lymphangitis
• Lymph node enlargement
• Inflammation (swelling, redness, heat)
• Blistering
• Local infection, abscess formation
• Necrosis 29
35. FIRST AID/PRE HOSPITAL CARE
• Reassure the victim
• Immobilize the bitten limb with a splint or sling
• Avoid any interference with the bite wound as this may introduce
infection, increase venom absorption & local bleeding
• All rings, watches, constricting clothing should be removed.
35
42. HOSPITAL MANAGEMENT, IF TOURNIQUET IS A
ALREADY IN PLACE
•Limb is ischemic – remove immediately
•Limb is not ischemic:
1) Snake (unknown) or neurotoxic – Don’t remove until definite
treatment (ASV) is initiated
2) Snake is viper – remove the tourniquet
42
44. INDIAN NATIONAL SNAKE BITE PROTOCOL
• Systemic envenomation
• Evidence of coagulopathy
• Evidence of neurotoxicity
• Cardiovascular abnormalities
• Persistent and severe vomitting
• Local envenomation
• Local swelling involving half of
the limb
• Rapid extension of swelling
Start ASV 45
45. ANTI SNAKE VENOMANTI SNAKE VENOM
• ASV is Ig purified from the serum/plasma of a horse/sheep immunizedASV is Ig purified from the serum/plasma of a horse/sheep immunized
with the venoms of one or more species of snake.with the venoms of one or more species of snake.
• Monovalent/PolyvalentMonovalent/Polyvalent
• The ASV in India is a polyvalent type which is active against theThe ASV in India is a polyvalent type which is active against the
commonly found snakes in India - FAB Four.commonly found snakes in India - FAB Four.
46
46. Polyvalent antivenoms from India
raised against venom from:
•Cobra
•Krait
•Russel’s viper
•Saw scaled viper
No monovalent vaccine in India
ANTI SNAKE VENOMANTI SNAKE VENOM
47
47. ANTI SNAKE VENOMANTI SNAKE VENOM
• ASV comes in two forms lyophilised powdered and liquid.
• Lyophilised ASV is simply liquid ASV freeze-dried.
48
48. ANTI SNAKE VENOMANTI SNAKE VENOM
• Always to be given only by slow IV route only.
• Never give IM route : poor bioavailability , painful and may increase
intra-compartmental pressure.
• Rate of infusion can be increased gradually in absence of reaction until
full starting dose is administered(0ver ~ 1 hour)
• Epinephrine (adrenaline) should always be drawn up in
readiness before ASV is administered
49
49. ANTI SNAKE VENOMANTI SNAKE VENOM
Each ml neutralizeEach ml neutralize
0.6 mg of cobra0.6 mg of cobra
0.6 mg of rusells viper0.6 mg of rusells viper
0.45 mg of krait0.45 mg of krait
0.45 mg of saw-scaled viper0.45 mg of saw-scaled viper
Average yield / biteAverage yield / bite
Cobra- 60 mg
Rusells- 63 mg
Krait- 20 mg
Saw-scaled- 13 mg
50
50. ANTI SNAKE VENOMANTI SNAKE VENOM
Neuroparalytic snakebite
ASV 10 vials stat as infusion over 30 minutes followed by 2nd dose of 10 vials after 1
hour if no improvement within 1st hour.
51
51. ANTI SNAKE VENOMANTI SNAKE VENOM
Vasculotoxic snakebite
Low Dose infusion therapy –
10 vials stat as infusion over 30
minutes followed by 2 vials every 6
hours as infusion in 100 ml of
normal saline till clotting time
normalizes or for 3 days whichever
is earlier.
High dose intermittent bolus
therapy - 10 vials of polyvalent
ASV stat over 30 minutes as
infusion, followed by 6 vials 6
hourly as bolus therapy till clotting
time normalizes and/or local
swelling subsides. 52
52. ANTI SNAKE VENOMANTI SNAKE VENOM
• Each vial of AVS be dissolved in 10 ml of distilled water and added to an
infusion medium such as normal saline
10 vials + 100 ml of distilled water + 400ml of normal saline
Given over 30-60 mins
NO Test Dose
53
53. PAEDIATRIC ASV DOSEPAEDIATRIC ASV DOSE
• Snakes inject the same dose of venom into children and adults.
• Children must therefore be given exactly the same dose of antivenom as
adults.
54
56. THERAPEUTIC ENDPOINTTHERAPEUTIC ENDPOINT
• Neuro /paralytic effect abolished – Presynaptic OnlyNeuro /paralytic effect abolished – Presynaptic Only
• Coagulation profile restored – repeat tests q6HCoagulation profile restored – repeat tests q6H
• Restoration of hemodynamics.Restoration of hemodynamics.
• Signs of local and systemic envenomation disappearsSigns of local and systemic envenomation disappears
• Active haemolysis and rhabdomyolysis ceases within a few hours and the urine
returns to its normal colour
• Patient improves clinicallyPatient improves clinically
57
57. ADVERSE ASV REACTIONADVERSE ASV REACTION
• Early anaphylactic reactions occurs within 10–180 min of start of
therapy and is characterized by itching, urticaria, dry cough, nausea and
vomiting, abdominal colic, diarrhoea, tachycardia, and fever.
• Some patients may develop severe life-threatening anaphylaxis
characterized by hypotension, bronchospasm, and angioedema
58
58. ADVERSE ASV REACTIONADVERSE ASV REACTION
• Pyrogenic reactionsPyrogenic reactions usually develop 1–2 h after treatment. Symptomsusually develop 1–2 h after treatment. Symptoms
include chills and rigors, fever, and hypotension.include chills and rigors, fever, and hypotension.
• Late (serum sickness–type) reactionsLate (serum sickness–type) reactions develop 1–12 (mean 7) daysdevelop 1–12 (mean 7) days
after treatment. Clinical features include fever, nausea, vomiting, diarrhea,after treatment. Clinical features include fever, nausea, vomiting, diarrhea,
itching, recurrent urticaria, arthralgia, myalgia, lymphadenopathy,itching, recurrent urticaria, arthralgia, myalgia, lymphadenopathy,
immune complex nephritis and, rarely, encephalopathyimmune complex nephritis and, rarely, encephalopathy
59
59. NEUROTOXIC ENVENOMATION
• Antivenom treatment alone cannot be relied upon to save the life of a patient
with bulbar and respiratory paralysis.
• Neostigmine is an anticholinesterase that prolongs the life of acetylcholineNeostigmine is an anticholinesterase that prolongs the life of acetylcholine
and can therefore reverse respiratory failure and neurotoxic symptomsand can therefore reverse respiratory failure and neurotoxic symptoms
• Effective for post synaptic neurotoxins – Cobra
• In all cases of neurotoxic envenomation theIn all cases of neurotoxic envenomation the 'AN challenge Test''AN challenge Test' to beto be
performedperformed
60
62. TAKE HOME MESSAGETAKE HOME MESSAGE
• Identify early signs of envenomation
• Manage as per “ABC” approach
• Start ASV early
• Prepare for anaphalytic reaction
• Surgical intervention
• Prevent multi organ failure
• Create public awareness
63
Farmers Snake Charmers Plantation work Workers at site Hunter
Workers at site Fisherman
WHO 2005
20 minute whole blood clotting test (20WBCT)
• Place a few mls of freshly sampled venous blood in a small glass vessel
• Leave undisturbed for 20 minutes at ambient temperature
• Tip the vessel once
• 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 Asian region, incoagulable blood is diagnostic of a viper bite and rules out an elapid bite
• Warning! If the vessel used for the test is not made of ordinary glass, or if it has been used before and cleaned with detergent, its wall may not stimulate clotting of the blood sample in the usual way and test will be invalid
• If there is any doubt, repeat the test in duplicate, including a “control” (blood from a healthy person)
Refer http://emedicine.medscape.com/article/771804-treatment
Figure 1, Apply a broad-pressure bandage over the bite site as soon as possible. Do not take off jeans because the movement of doing so assists venom to enter the bloodstream. Keep the bitten leg still.
Figure 2, The bandage should be as tight as would be applied to a sprained ankle.
Figure 3, Extend the bandage as high as possible.
Figure 4, Apply a splint to the leg.
Figure 5, Bind the splint firmly to as much of the leg as possible. If the bandages and splint are applied correctly, they will be comfortable and may be left on for several hours. They should not be taken off until the patient has reached medical care. The doctor will decide when to remove the bandages. If venom has been injected, it will move into the bloodstream quickly once the bandages are removed. The doctor should leave the bandages and splint in position until he or she has assembled appropriate antivenom and drugs that may need to be used when the dressings and splint are removed.
Figure 6, For bites on a hand or forearm, bind to the elbow with bandages, use a splint to the elbow, and use a sling.
ONLY if a Patient develops one or more of the following signs/symptoms will ASV be administered:
Systemic envenoming
Evidence of coagulopathy: Primarily detected by 20WBCT or visible spontaneous systemic bleeding, gums etc. Further laboratory tests for thrombocytopenia, Hb abnormalities, PCV, peripheral smear etc provide confirmation, but 20WBCT is paramount.
Evidence of neurotoxicity: ptosis, external ophthalmoplegia, muscle paralysis, inability to lift the head etc. The above two methods of establishing systemic envenomation are the primary determinants. They are simple to carry out, involving bedside tests or identification of visible neurological signs and symptoms. In the Indian context and in the vast majority of cases, one of these two categories will be the sole determinant of whether ASV is administered to a patient.
Cardiovascular abnormalities: hypotension, shock, cardiac arrhythmia,
abnormal ECG.
Persistent and severe vomiting or abdominal pain.
Severe Current Local envenoming
Severe current, local swelling involving more than half of the bitten limb (in the absence of a tourniquet). In the case of severe swelling after bites on the digits (toes and especially fingers) after a bite from a known necrotic species.
Rapid extension of swelling (for example beyond the wrist or ankle within a few hours of bites on the hands or feet). Swelling a number of hours old is not grounds for giving ASV.
Purely local swelling, even if accompanied by a bite mark from an apparently venomous snake, is not grounds for administering ASV
ASV is recommended to be administered in the following initial dose:
Neurotoxic/ Anti Haemostatic 8-10 Vials
N.B. Children receive the same ASV dosage as adults. The ASV is targeted at neutralising the venom. Snakes inject the same amount of venom into adults and children.
ASV can be administered in two ways:
Intravenous Injection: reconstituted or liquid ASV is administered by slow intravenous injection. (2ml/ minute). Each vial is 10ml of reconstituted ASV.
Infusion: liquid or reconstituted ASV is diluted in 5-10ml/kg body weight of isotonic saline or glucose.
ASV is recommended to be administered in the following initial dose:
Neurotoxic/ Anti Haemostatic 8-10 Vials
N.B. Children receive the same ASV dosage as adults. The ASV is targeted at neutralising the venom. Snakes inject the same amount of venom into adults and children.
ASV can be administered in two ways:
Intravenous Injection: reconstituted or liquid ASV is administered by slow intravenous injection. (2ml/ minute). Each vial is 10ml of reconstituted ASV.
Infusion: liquid or reconstituted ASV is diluted in 5-10ml/kg body weight of isotonic saline or glucose.
Repeat Doses: Anti Haemostatic
In the case of anti haemostatic envenomation, the ASV strategy will be based around a six hour time period. When the initial blood test reveals a coagulation abnormality, the initial ASV amount will be given over 1 hour.
No additional ASV will be given until the next Clotting Test is carried out. This is due to the inability of the liver to replace clotting factors in under 6 hrs.
After 6 hours a further coagulation test should be performed and a further dose should be administered in the event of continued coagulation disturbance. This dose should also be given over 1 hour. CT tests and repeat doses of ASV should continue on a 6 hourly pattern until coagulation is restored, unless a species is identified as one against which Polyvalent ASV is not effective.
The repeat dose should be 5-10 vials of ASV i.e. half to one full dose of the original amount. The most logical approach is to administer the same dose again, as was administered initially. Some Indian doctors however, argue that since the amount of unbound venom is declining, due to its continued binding to tissue, and due to the wish to conserve scarce supplies of ASV, there may be a case for administering a smaller second dose. In the absence of good trial evidence to determine the objective position, a range of vials in the second dose has been adopted
Indian journal of science & technology vol 2. no.10
In the Indian setting, almost two-thirds of bites are attributed to Saw-scaled viper (as high as 95% in some areas like
Jammu), about one fourth to Russell's viper and smaller proportions to Cobra and Kraits
Snake venom was injected in small amounts into mammals such as horses, sheep or rabbits. These animals have an immune response whereby antibodies against venom are generated naturally. The antivenom is then harvested from the blood of the animal, purified and stored. In India polyvalent antisnake venom effective against venoms of Cobras,
Krait, Russell's viper and Saw-scaled viper is available. Each ml of polyvalant antisnake venom can neutralize 0.6mg of Cobra, 0.6mg of Russell’s viper, 0.45mg of Krait and 0.45mg of Saw-scaled viper venom
the average yield per bite in terms of dry weight of lyophilized venom is 60mg for Cobras, 63mg for Russell's viper, 20mg for Krait and 13mg for Sawscaled viper
The respective ‘fatal doses’ are much smaller viz 12mg, 15mg, 6mg and 8mg
WHO 2005
Antibodies raised against the venom of one species may have cross-neutralising activity against other venoms, usually from closely related species. This is known as paraspecific activity. For example, the manufacturers of Haffkine polyvalent anti-snake venom serum claim that this antivenom also neutralises venoms of two Trimeresurus species
Indian journal of science & technology vol 2. no.10
In the Indian setting, almost two-thirds of bites are attributed to Saw-scaled viper (as high as 95% in some areas like
Jammu), about one fourth to Russell's viper and smaller proportions to Cobra and Kraits
Snake venom was injected in small amounts into mammals such as horses, sheep or rabbits. These animals have an immune response whereby antibodies against venom are generated naturally. The antivenom is then harvested from the blood of the animal, purified and stored. In India polyvalent antisnake venom effective against venoms of Cobras,
Krait, Russell's viper and Saw-scaled viper is available. Each ml of polyvalant antisnake venom can neutralize 0.6mg of Cobra, 0.6mg of Russell’s viper, 0.45mg of Krait and 0.45mg of Saw-scaled viper venom
the average yield per bite in terms of dry weight of lyophilized venom is 60mg for Cobras, 63mg for Russell's viper, 20mg for Krait and 13mg for Sawscaled viper
The respective ‘fatal doses’ are much smaller viz 12mg, 15mg, 6mg and 8mg
WHO 2005
Antibodies raised against the venom of one species may have cross-neutralising activity against other venoms, usually from closely related species. This is known as paraspecific activity. For example, the manufacturers of Haffkine polyvalent anti-snake venom serum claim that this antivenom also neutralises venoms of two Trimeresurus species