Community Medicine Presentations - Snakebite
Transcript of Community Medicine Presentations - Snakebite
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Snake bite
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Snake bite is :
- Amajor public health problem & animportant cause ofmorbidity and mortality ,specially in the tropics
And our country is not exception -
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Out of 2700 species (some authors claim3000) 500
belong to three important families :-with longvasculotoxic:Viperidae-1
erectile fangs.
2- Elapidae :Neurotoxic with short fangs.
3- Hydrophidae : Myotoxic with short
fangs & flat tail.
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Very long fangs
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Envenomation
Envenomation is either through:1- Bites
2- Spray of venom into the eyes of theaggressor.
Some bites may be defensive without
.injecting the venom
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Venom composition
20 or more components & 90 % of thedry weight is protein.
:Polypeptide enzymes-1
a- Proteases: activate blood clotting cascb- Phospholipases: cytolytic & produces
presynaptic neurotoxin that prevent
release of Ach at the N/ muscularjunction.
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c- Hydrolases: increase vascularpermeability and causes edema,blistering, bruises and necrosis.
d- Hyaluronidases: promote spread ofvenom through the tissues.
e-Amino acid oxidases: digestive. enzymatic polypeptide toxins-Non-2(Elapidae & Hydrophidae) containspostsynaptic neurotoxins that bind to
Ach receptors at the motor end platesand cause paralysis.
contribute to local painHT5Histamines &-3
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and permeability at the bite site.
.toxic proteins-Non-4
include CHO,Non protein ingredients-5lipids, amino acids & amines.
:In conclusion
Snake venoms contain a variety oftoxins and the variation of its
composition from sp. to sp. explainsthe clinical diversity of snake bites.from family to family
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Pathophysiology
of venom from bite siteAbsorption-1
depends on the tissue binding affinityof the venom components, mol. sizeand the local effects of za venom on
tissue permeability & blood supply.is due to increasedLocal swelling-2
vascular permeability leading to
swelling, blisters and bruising.Systemic envenomation may causeserous effusions and pulm edema.
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-results from :Local tissue necrosis-3a- Direct action of myotoxic and
cytolytic factorsb- Ischemia due to:- thrombosis
- Compression by tight tourniquet- Compression of arteries byswollen muscles within a tight
facial compartment
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may occur withinHypotension & shock-4minutes due to:-
- Vasodilating amines- leak of plasma & blood into bitten
limb & elsewhere
- Massive GIT bleeding
- Direct effects of toxins on the
myocardium
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are due to:Bleeding & clotting disturb-5
- DIC
- Thrombocytopenia- Haemorrhagin which damage vascularendothelium.
The combination ofdefibrination,thrombocytopenia and vessel wall
damage result in massive bleeding
specially in Viper bites
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:Intravascular haemolysis-6
Rare, but massive intravascular
haemolysis can lead to acute renalfailure
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is rare complication ofRenal failure-7
severe envenomation due to:-
- ATN from prolonged hypotension- DIC- Direct tubular toxicity
- HBuria- Myoglobinuria- Hyperkalaemia..
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:Neurotoxicity-8
Neurotoxic polypeptie & phospholipases
cause paralysis by blocking N/ musculartransmission. Death may follow:
- Respiratory muscle paralysis +++
- Bulbar palsy causing resp obstructionor paralysis.
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with release ofRabdomyolysis-9
myoglobin, muscle enzymes & K.
Death may follow :-- respiratory paralysis- bulbar palsy,
- acute hyperkalaemia- later renal failure.
: Spray from spittingVenous ophthalmia-10
cobras leads to corneal erosions,conjunctivitis, anterior uveitis &secondary infections
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-:Clinical featuresFEETMost bites are on the-1
2- Envenomation is not inevitable even insevere bites. Snake bites are unpredictableso keep the pat. in for 24 hrs.
-3- Diseasemay result from fear, anxiety, localTR or from Envenomation
-4- Nearly 50% of people bitten by snakes
-suffer few or no toxic effects. On the other-hand mortality without effective TR is high
%)15up to(
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Viperidae-1
.othersthanlocal effectsmoreproduce
- Early syncope, nausea, vomiting,colics, diarrhea, angioedema & wheezemay occur.
- Hypotension & shock may occur early.-Local painful swelling and maybecome massive & spread up za limb in
2-3 days with tender L. nodes.Absence of swelling 2 hrs after biteusually mean no envenomation
l bl d
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- Blistering & bleeding at puncture site areearly symptoms. Spreading bruising and
blistering suggest a large dose ofvenom and may proceed to necrosiswithsecondary infections.
-Very severe pain & tense swelling mayindicate intercompartmental pressure.
- Sudden severe pain, absence major of
arterial pulsesand demarcated cold limbindicate thrombosis of artery.
S i bl di G
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-Spontaneous systemic bleeding: Gumbleeding, ecchymosis, conjunctival
haemorrhage, Hria, GIT bleeding,menorrhg , intra or retroperitoneal
bleeding SAH and intracerebral
bleeding. Haemoptysis is rare.Incoagulable blood from defibrinationmay occur.
-- Necrosis of patient skin, S/C tissue andmuscles. 2ryInfection with offensivesmell may follow
Ti i f i &
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mayTissue infarction & gangrene-follow vascular thrombosis.
mayAnemia, jaundice & black urine-result from haemolysis.
.may complicateRenal failure-
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Elapidae-2
- Local tissue swelling is a feature of Asian
Cobras & African spitting Cobras. Thebite is painful and may be followed bynecrosis.
-Vomiting, hypotension & polymorphleucocytosis suggest systemicenvenomation
- More specific features include ptosis andophthalmoplegia. Bulbar palsy and respparalysis and failure in severe cases
- ECG changes & raised cardiac enzymes.
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3
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Hydrophidae-3 - Early signs similar to Elapidae
- Specific signs include myalgia andmyoglobinuria 3-5 hrs later.
- Limb paralysis may be followed by respparalysis & failure which may bedelayed for up to 60 hrs.
- Hyperkalaemia may cause cardiac arrest-Acute renal failure may follow.
i
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-Course & prognosis:
- Local swelling is usually evident within 2
hours, max in za 2nd or 3rd day & maytake Ws or Ms to resolve.
- Pats may be totally defibrinated in 1-2
hours after bite by viperidae.
- Deaths most unusual before hour.
- Untreated mortality is hard to assessas hospital admissions include the mainlysevere cases. It can be reduced by TR.
I t l b t bit & d th b
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- Interval betw bite & death may be asearly as few min. or as long as 6 Ws.
.Prognosis is worse in infants & elderly-
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Laboratory
- Neutrophil leucocytosis
- Decreased haematocrit
- Thrombocytopenia
- Increased FDP- Prolonged PT
- Incoagulable blood
- Increased CPK; AST & ALT
- Urine ex, BUN & E.
Management of snake bite
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Management of snake biteFirst aids
1 - Reassure the victim
2 - Immobilize the bitten limb using splintand crepe bandage.
3 - Take za victim quickly to za nearesthealthfacility.
4 -Avoid harmful time wasting TR:
(cauterization, incision & excision,vacuum or mouth suction, localchemicals, cryotherapy & arterialtourniquet )
5 T k k t h it l if kill d
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5- Take snake to za hospital if killed.
TR of early symptoms
1- Paracetamol. Not aspirin.2 - IV chlorpromazine for vomiting
3- IV chlorpheneramine or S/C adr., IVfluids for anaphylaxis and shock
4- Clear the air way, nurse pat on his side,
insert airway & elevate the jaw,artificial ventilation & oxygen for respdistress
TR at health facilityC
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TR at health facility-C
med emergencySnake bite is a-1
2- Quick clinical assessment:( site of bite, duration of bite, snakebrought vomiting & fainting, fang
marks, any bleeding, local signs, lookfor blood in gingival sulci & recentwounds, look for signs of shock and
TR, signs of neurotoxicity, colourand amount of urine)
3 Observe closely pat for 24 hrs even if no
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3- Observe closely pat for 24 hrs even if noSnake bite is unpredictablesigns.
4-Anti-venom administration:-It is za only specific therapy & shouldbe given in excess of za venom injected
as soon as it is indicatedWhether to give or not ? May producesevere reactions, expensive & in short
supply
includeIndications for administration
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includeIndications for administration
a- Systemic envenomation:
1- Haemostatic abnormality:- spontaneoussystemic bleeding, incoagulable blood,prolonged PT, FDP and thrombocytop
2- Acute renal failure:- oliguria/ anuria-biochem
3- Cardiovascular abn.( hypot, shock, HF
abn. ECG & pulm edema)
4 Neurotoxicity (Ptosis, ophthalmoplegia,
paralysis)
5 Generalized rhabdomyolysis and
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5- Generalized rhabdomyolysis andintravascular haemolysis
b- Local envenomation:
1- Signs of local envenomation +(neutrophil leucocytosis, high CPK,
AST and ALT, haemococ and
hypoxaemia)2- Severe local swelling extending more
than of za bitten limb or blistering
or bruising) at any stage specially inpats showing biochemicalabnormalities in 1.
C- impaired consciousness
venomAdministration of antiD
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venom-Administration of anti-D
- Preliminary testing is not necessary
and delays TR.- Multival anti- venom is given as soon
as it is indicated & it is never late e.g
for 2/52 or more in persisting
haemostatic abnormalities. Local effects ofthe venom are probably not reversible if
anti- venom is delayed more than 2 hours- Slow IV infusion diluted in 250-500 ml
NS or DNS over hr. Rarely slow IV
injection at 2 ml/min.
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180-10developvenom-Reaction to anti-E
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18010developvenomReaction to antiEmin after administration & treated by adr,hydrocortisone & antihistamine. In severe
envenomation continue infusion despitereaction with S/C and adr as necessary
- Anaphylactoid
- Pyrogenic- Serum sicknessfor neurotoxicitycholinesterase-Anti-F
Supportive TR-G
-Artificial ventilation for neurotoxic bites.
Anticholinesterases should always be tried
- Plasma expander & dopamine for shock.
- conservative management or dialysis for
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-- conservative management or dialysis forrenal failure
-Antibiotic +/- ATS for local infection
- Incision for intercompartmental synr
- Strict bed rest, fresh blood, fresh frozenplasma or specific clotting factors & vit K forhaemostatic abn. Avoid IM & repeatedvenepuncture. Use IV canulae. Heparin andanti- fibrinolytic agents ?
.Local tissue debridement & skin graft-H
(precautions)Prevention of snake bite
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(precautions)Prevention of snake bite- Snakes should never unnecessarily bedisturbed, handled or attacked even if they
are thought to be harmless or dead-Avoid venomous sp. as pets
- Protective clothings, boots, socks & long
trousers should be worn by persons at risk.- Carry light at night sp. for farmers, harvesters,fire wood collectors & for those removingdebris likely to conceal snakes
- Immunization with venom toxoid to those atrisk.
Snake bite is :
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Snake bite is :- Amajor public health problem and an
important cause ofmorbidity and mortality ,specially in the tropics
- It is important occupational disease
- Goverments, academic institutions, pharmaceut
agricultural bodies should encourage & sponsor
clinical studies in all aspects of snake bite.- Education & training on snake bite should be
included in the curriculum of medical schools.- Community education on snake bites ,first
aid methods and preventive measures is
recommended.
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THANK YOU
And Goodbye