community medicine presentations - snakebite

7/28/2019 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.


10/42Cellulitis of hand


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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.


25/42Ptosis & ophthalmoplegia

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

community medicine presentations - snakebite

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