Snake biteSnake bite By Dr. Osman Sadig By Dr. Osman Sadig BukhariBukhari

Snake bite isSnake bite is: : - -A A major public health problemmajor public health problem & an & an

important cause of important cause of morbiditymorbidity and and mortalitymortality , specially in the tropics , specially in the tropics

- - In 2002/2003/2004In 2002/2003/2004 628 628 cases were cases were admitted in Gedarif Teaching admitted in Gedarif Teaching Hospital withHospital with

88 deathsdeaths..

Out of 2700 species 500 belong to Out of 2700 species 500 belong to three important familiesthree important families-: -:

11 - -ViperidaeViperidae : : vasculotoxicvasculotoxic with long with long erectile fangs erectile fangs . .

22 - -ElapidaeElapidae : :Neurotoxic Neurotoxic with short with short fangsfangs..

33 - -HydrophidaeHydrophidae : : MyotoxicMyotoxic with short with short fangs & flat tail fangs & flat tail..

A common Sea snake of S E Asia

Thai spitting Cobra

Short front fangs

Very long fangsVery long fangs

EnvenomationEnvenomation Envenomation is either through: Envenomation is either through:

1- 1- BitesBites

22 - -SpraySpray of venom into the eyes of of venom into the eyes of the aggressorthe aggressor . .

Some bites may be defensive Some bites may be defensive withoutwithout injecting the venominjecting the venom..

Venom compositionVenom composition

2020 or more components & 90 % of or more components & 90 % of the dry weight is proteinthe dry weight is protein . .

11 - -Polypeptide enzymesPolypeptide enzymes: :

a- a- ProteasesProteases: activate blood clotting : activate blood clotting casccasc

b- b- PhospholipasesPhospholipases: cytolytic & : cytolytic & produces presynaptic produces presynaptic neurotoxin that prevent release neurotoxin that prevent release of Ach at the N/ muscular of Ach at the N/ muscular junctionjunction..

c- c- HydrolasesHydrolases: increase vascular : increase vascular permeability and causes edema, permeability and causes edema,

blistering, bruises and necrosis blistering, bruises and necrosis . . d- d- Hyaluronidases:Hyaluronidases: promote spread of promote spread of

venom through the tissues venom through the tissues.. e- e- Amino acid oxidases:Amino acid oxidases: digestive digestive..

22 - -Non- enzymatic polypeptide toxinsNon- enzymatic polypeptide toxins (Elapidae & Hydrophidae) (Elapidae & Hydrophidae) contains postsynaptic contains postsynaptic neurotoxins that bind to Ach neurotoxins that bind to Ach receptors at the motor end plates receptors at the motor end plates

and cause paralysisand cause paralysis . .33 - -Histamines & 5HTHistamines & 5HT contribute to local contribute to local

painpain

and permeability at the bite siteand permeability at the bite site . .

44 - -Non- toxic proteinsNon- toxic proteins. . 5- Non protein ingredients5- Non protein ingredients include include CHO, lipids, amino acids & CHO, lipids, amino acids & aminesamines..

In conclusionIn conclusion::

Snake venoms contain a variety Snake venoms contain a variety of toxins and the variation of of toxins and the variation of its composition from sp. its composition from sp. to sp. explains the clinical to sp. explains the clinical diversity of snake bites from diversity of snake bites from family to familyfamily to family . .

Pathophysiology1 -Absorption of venom from bite site

depends on the tissue binding affinity of the venom components, mol. size and the local effects of za venom on tissue permeability & blood supply.

2 -Local swelling is due to increased vascular permeability leading to swelling, blisters and bruising. Systemic envenomation may cause serous effusions and pulm edema.

Cellulitis of hand

Blisters on za feet

Massive swelling & bulla formation

Pulmonary oedema

3 -Local tissue necrosis results from :- a- Direct action of myotoxic and cytolytic factors b- Ischemia due to: - thrombosis - Compression by tight tourniquet - Compression of arteries by swollen muscles within a tight

facial compartment

Extensive loss of skin & muscles

44 - -Hypotension & shockHypotension & shock may occur may occur within minutes due towithin minutes due to-:-:

- - Vasodilating aminesVasodilating amines

- - leak of plasma & blood into bittenleak of plasma & blood into bitten

limb & elsewherelimb & elsewhere

- - Massive GIT bleedingMassive GIT bleeding

- - Direct effects of toxins on theDirect effects of toxins on the

myocardiummyocardium

55 - -Bleeding & clotting disturbBleeding & clotting disturb are due are due to: - DIC to: - DIC - Thrombocytopenia - Thrombocytopenia - Haemorrhagin which - Haemorrhagin which damage vascular endothelium. damage vascular endothelium. The The combination of combination of defibrinationdefibrination, , thrombocytopeniathrombocytopenia and and vessel wallvessel wall

damage damage result in massive bleedingresult in massive bleeding

specially in Viper bitesspecially in Viper bites

Haematuria

66 - -Intravascular haemolysisIntravascular haemolysis::

Rare, but massive intravascular Rare, but massive intravascular haemolysis can lead to haemolysis can lead to acute renal failureacute renal failure

77 - -Renal failureRenal failure is rare complication is rare complication of severe envenomation due of severe envenomation due to:- - ATN from prolonged to:- - ATN from prolonged hypotension - DIC hypotension - DIC - Direct tubular - Direct tubular toxicity - HBuria toxicity - HBuria - - Myoglobinuria Myoglobinuria

- Hyperkalaemia- Hyperkalaemia .. ..

88 - -NeurotoxicityNeurotoxicity::

Neurotoxic polypeptie & Neurotoxic polypeptie & phospholipases phospholipases cause paralysis cause paralysis by blocking N/ muscularby blocking N/ muscular

transmissiontransmission. Death may follow. Death may follow : :

- - Respiratory muscle paralysisRespiratory muscle paralysis+++ +++

- - Bulbar palsy causingBulbar palsy causing resp resp obstruction or paralysisobstruction or paralysis . .

99 - - RabdomyolysisRabdomyolysis with release of with release of myoglobin, muscle enzymes & myoglobin, muscle enzymes & K. Death may follow :- K. Death may follow :- - respiratory paralysis - respiratory paralysis - bulbar palsy, - bulbar palsy, - acute - acute hyperkalaemia - later hyperkalaemia - later renal failurerenal failure..

1010 - -Venous ophthalmiaVenous ophthalmia: Spray from : Spray from spitting cobras leads to corneal spitting cobras leads to corneal erosions, conjunctivitis, erosions, conjunctivitis, anterior uveitis & secondary anterior uveitis & secondary infectionsinfections

Clinical featuresClinical features-:-: 11 - -Most bites are on the Most bites are on the FEETFEET

2- 2- Envenomation is not inevitableEnvenomation is not inevitable even in severe bites. even in severe bites. Snake bites Snake bites are unpredictable so keep the pat. in are unpredictable so keep the pat. in

for 24 hrsfor 24 hrs . .- 33 - -DiseaseDisease may result from may result from fear, fear,

anxiety, localanxiety, local TR or from EnvenomationTR or from Envenomation- 44 - -Nearly 50% of people bitten by snakesNearly 50% of people bitten by snakes

- suffer suffer few or no toxic effectsfew or no toxic effects. On the . On the otherother

- hand hand mortality without effective TR is mortality without effective TR is highhigh ( (up to 15%)up to 15%)

11 - -ViperidaeViperidae

produce produce moremore local effects local effects thanthan othersothers. . - - Early syncope, nausea, Early syncope, nausea, vomiting, colics, diarrhea, vomiting, colics, diarrhea, angioedema & wheeze may occur. angioedema & wheeze may occur. - Hypotension & - Hypotension &

shock may occur earlyshock may occur early . .

- - Local painful swellingLocal painful swelling and may and may become massive & spread up za become massive & spread up za limb in 2-3 days with tender L. limb in 2-3 days with tender L. nodes. Absence of swelling 2 nodes. Absence of swelling 2 hrs after bite usually mean no hrs after bite usually mean no envenomationenvenomation

- -Blistering & bleeding at puncture siteBlistering & bleeding at puncture site are early symptoms. Spreading are early symptoms. Spreading bruisingbruising and and blisteringblistering suggest a suggest a large dose of venom and may large dose of venom and may proceed to proceed to necrosis withnecrosis with

secondary infectionssecondary infections . .

- - Very severe pain & tense swellingVery severe pain & tense swelling may indicate intercompartmental may indicate intercompartmental pressure. - pressure. - Sudden severe pain, Sudden severe pain, absence major of arterial pulsesabsence major of arterial pulses and and demarcated cold limb indicate demarcated cold limb indicate

thrombosis of arterythrombosis of artery..

- -Spontaneous systemic bleedingSpontaneous systemic bleeding: Gum : Gum bleeding, ecchymosis, conjunctival bleeding, ecchymosis, conjunctival haemorrhage, Hria, GIT bleeding, haemorrhage, Hria, GIT bleeding, menorrhg menorrhg , , intra or intra or retroperitoneal bleeding SAH retroperitoneal bleeding SAH and intracerebral bleeding. and intracerebral bleeding. Haemoptysis is rare. Haemoptysis is rare. Incoagulable bloodIncoagulable blood from defibrination from defibrination may occur. may occur. Hage into vital organs may be Hage into vital organs may be fatalfatal - - Necrosis of za skin, S/C tissue Necrosis of za skin, S/C tissue and muscles. 2ryand muscles. 2ry InfectionInfection with with offensive smell may followoffensive smell may follow

- -Tissue infarction & gangreneTissue infarction & gangrene may follow vascular thrombosismay follow vascular thrombosis..

- - Anemia, jaundice & black urine Anemia, jaundice & black urine may result from haemolysismay result from haemolysis . .

- - Renal failureRenal failure may complicate may complicate..

22 - -ElapidaeElapidae - - Local tissue swellingLocal tissue swelling is a feature of is a feature of

Asian Cobras & African spitting Asian Cobras & African spitting Cobras. The Cobras. The bite is painfulbite is painful and may and may be followed by be followed by necrosisnecrosis . .

- - Vomiting, hypotension & polymorphVomiting, hypotension & polymorph leucocytosis suggest systemic leucocytosis suggest systemic envenomation envenomation

- - More specific features include More specific features include ptosis ptosis andand ophthalmoplegia. B ophthalmoplegia. Bulbar palsy ulbar palsy and resp paralysis and failureand resp paralysis and failure in in severe casessevere cases

- - ECG changes & raised cardiac enzymesECG changes & raised cardiac enzymes..

Ptosis & ophthalmoplegia

33-- HydrophidaeHydrophidae - - Early signs similar to ElapidaeEarly signs similar to Elapidae

- - Specific signs include Specific signs include myalgiamyalgia and and myoglobinuriamyoglobinuria 3-5 hrs later 3-5 hrs later..

- - Limb paralysisLimb paralysis may be followed by may be followed by respresp paralysis & failureparalysis & failure which may which may be delayed for up to 60 hrsbe delayed for up to 60 hrs . .

- - HyperkalaemiaHyperkalaemia may cause cardiac may cause cardiac arrestarrest

- - Acute renal failureAcute renal failure may follow may follow..

Course & prognosisCourse & prognosis-:-:

- - Local swellingLocal swelling is usually evident is usually evident within 2 hours, max in za 2within 2 hours, max in za 2ndnd or 3 or 3rdrd day & may take Ws or Ms to day & may take Ws or Ms to

resolveresolve . .

- - Pats may be totallyPats may be totally defibrinated defibrinated in 1- in 1-2 hours after bite by viperidae2 hours after bite by viperidae..

- - Deaths most unusual before ½ hourDeaths most unusual before ½ hour..

- - Untreated mortality is hard to assessUntreated mortality is hard to assess

as hospital admissions include the as hospital admissions include the mainly severe cases. It can be mainly severe cases. It can be reduced by TRreduced by TR..

- - Interval betw bite & deathInterval betw bite & death may be may be as early as few min. or as long as early as few min. or as long as 6 Ws. - as 6 Ws. - Prognosis is worse in Prognosis is worse in infants & elderlyinfants & elderly..

LaboratoryLaboratory

- - Neutrophil leucocytosisNeutrophil leucocytosis

- - Decreased haematocritDecreased haematocrit

- - ThrombocytopeniaThrombocytopenia

- - Increased FDPIncreased FDP

- - Prolonged PTProlonged PT

- - Incoagulable bloodIncoagulable blood

- - Increased CPK; AST & ALTIncreased CPK; AST & ALT

- - Urine ex, BUN & EUrine ex, BUN & E..

Management of snake bite Management of snake bite First aidsFirst aids

11 - - ReassureReassure the victim the victim 22 - - Immobilize the bitten limbImmobilize the bitten limb using using

splint and crepe bandagesplint and crepe bandage.. 33 - - Take za victim Take za victim quickly to za quickly to za

nearest healthnearest health facilityfacility.. 44 - - Avoid harmful time wasting TR:Avoid harmful time wasting TR:

(cauterization, incision & (cauterization, incision & excision, vacuum or mouth excision, vacuum or mouth suction, local chemicals, suction, local chemicals, cryotherapy & arterial cryotherapy & arterial tourniquettourniquet ) )

55 - -Take snake to za hospital if killedTake snake to za hospital if killed..

TR of early symptomsTR of early symptoms

11 - -ParacetamolParacetamol. Not aspirin. Not aspirin..

22 - - IV chlorpromazineIV chlorpromazine for vomiting for vomiting

33 - -IV IV chlorpheneramine or S/C adr., IV chlorpheneramine or S/C adr., IV fluids fluids for anaphylaxis and for anaphylaxis and shockshock

44 - -Clear the air way, nurse pat on his Clear the air way, nurse pat on his side, insert airway & elevate the side, insert airway & elevate the jaw, artificial ventilation & jaw, artificial ventilation & oxygen for oxygen for resp distressresp distress

C- C- TR at health facilityTR at health facility

11 - -Snake bite is a Snake bite is a med emergencymed emergency

22 - -Quick clinical assessment: Quick clinical assessment: ( site of bite, duration of bite, ( site of bite, duration of bite, snake brought vomiting & snake brought vomiting & fainting, fang marks, any fainting, fang marks, any bleeding, local signs, look for bleeding, local signs, look for blood in gingival sulci & recent blood in gingival sulci & recent wounds, look for signs of shock and wounds, look for signs of shock and TR, signs of neurotoxicity, colour TR, signs of neurotoxicity, colour

and amount of urine) and amount of urine)

33 - -Observe closely pat for 24 hrsObserve closely pat for 24 hrs even even if no signs. if no signs. Snake bite is Snake bite is unpredictableunpredictable 4- 4- Anti-venom Anti-venom administrationadministration-:-:

It is za It is za only specific therapyonly specific therapy & should & should be given in excess of za venom be given in excess of za venom injected as soon as it is indicatedinjected as soon as it is indicated

Whether to give or not ?Whether to give or not ? May May produce severe reactions, produce severe reactions, expensive & in short supplyexpensive & in short supply

Indications for administrationIndications for administration includeinclude

a- Systemic envenomationa- Systemic envenomation::

11 - -Haemostatic abnormality:- Haemostatic abnormality:- spontaneous systemic bleeding, spontaneous systemic bleeding, incoagulable blood,incoagulable blood, prolonged PT, prolonged PT, FDP and thrombocytopFDP and thrombocytop

22 - -Acute renal failure:- oliguria/ anuria- Acute renal failure:- oliguria/ anuria- biochem biochem

33 - -Cardiovascular abn.( hypot, shock, HFCardiovascular abn.( hypot, shock, HF

abn. ECG & pulm edemaabn. ECG & pulm edema))

44 – – Neurotoxicity (Ptosis, Neurotoxicity (Ptosis, ophthalmoplegia, paralysis)ophthalmoplegia, paralysis)

55 - -Generalized rhabdomyolysis and Generalized rhabdomyolysis and intravascular haemolysis intravascular haemolysis b- Local envenomationb- Local envenomation: : 1- Signs of local envenomation + 1- Signs of local envenomation + (neutrophil leucocytosis, high (neutrophil leucocytosis, high CPK, AST and ALT, haemococ CPK, AST and ALT, haemococ

and hypoxaemia)and hypoxaemia) 22 - -Severe local swelling extending Severe local swelling extending

more than ½ of za bitten limb or more than ½ of za bitten limb or blistering or bruising) at any stage blistering or bruising) at any stage specially in pats showing specially in pats showing biochemical biochemical abnormalities in 1abnormalities in 1 . .C- impaired consciousnessC- impaired consciousness

D- D- Administration of anti-venomAdministration of anti-venom

- -Preliminary testing is not necessaryPreliminary testing is not necessary

and delays TRand delays TR..

- - Multival anti- venomMultival anti- venom is given as soon is given as soon

as it is indicated & it is never late e.gas it is indicated & it is never late e.g

for 2/52 or more in persistingfor 2/52 or more in persisting

haemostatic abnormalities. haemostatic abnormalities. Local effects Local effects of the venomof the venom are probably are probably not not reversible if anti- venom is delayed reversible if anti- venom is delayed more than 2 hours more than 2 hours - - Slow IV infusionSlow IV infusion diluted in 250-500 mldiluted in 250-500 ml

NS or DNS over ½ hr. Rarely slow IVNS or DNS over ½ hr. Rarely slow IV

injection at 2 ml/mininjection at 2 ml/min . .

- -No absolute contraindication No absolute contraindication DoseDose= amount of antivenom required to = amount of antivenom required to neutralize the venom injected. neutralize the venom injected. In practice it is empirical. 2-10 In practice it is empirical. 2-10 amp, but it should be based on amp, but it should be based on studies. Dose can be repeated. studies. Dose can be repeated. 22ndnd dose if cardio-resp or dose if cardio-resp or neurotoxic symptoms persist for neurotoxic symptoms persist for > 30 min or in > 30 min or in incoagulable blood > 6 hrs after incoagulable blood > 6 hrs after initial dose. initial dose. - - Same dose for childrenSame dose for children..

- - The response to anti-venom is quickThe response to anti-venom is quick

if sufficient dose is givenif sufficient dose is given

E- E- Reaction to anti-venomReaction to anti-venom develop 10-180 develop 10-180 min after administration & treated by min after administration & treated by adr, hydrocortisone & antihistamine. In adr, hydrocortisone & antihistamine. In severe envenomation continue infusion severe envenomation continue infusion despite reaction with S/C and adr as despite reaction with S/C and adr as

necessarynecessary - - AnaphylactoidAnaphylactoid

- - PyrogenicPyrogenic - - Serum sickness Serum sickness F- F-

Anti-cholinesteraseAnti-cholinesterase for neurotoxicity for neurotoxicityG- G- Supportive TRSupportive TR

- - Artificial ventilationArtificial ventilation for neurotoxic bites for neurotoxic bites.. Anticholinesterases should always be Anticholinesterases should always be

triedtried - - Plasma expander & dopamine for shockPlasma expander & dopamine for shock..

- - - conservative conservative managementmanagement or dialysis or dialysis for renal failurefor renal failure

- - Antibiotic +/- ATS for local infectionAntibiotic +/- ATS for local infection

- - Incision for intercompartmental synrIncision for intercompartmental synr

- - Strict bed rest, fresh blood, fresh frozen Strict bed rest, fresh blood, fresh frozen plasma or specific clotting factors plasma or specific clotting factors & vit K for haemostatic abn. Avoid IM & & vit K for haemostatic abn. Avoid IM & repeated venepuncture. Use IV repeated venepuncture. Use IV canulae. Heparin and anti- fibrinolytic canulae. Heparin and anti- fibrinolytic

agentsagents? ?

H- Local tissue debridement & skin H- Local tissue debridement & skin graftgraft..

Prevention of snake bitePrevention of snake bite (precautions) (precautions) - - Snakes should never unnecessarily be Snakes should never unnecessarily be

disturbed, handled or attacked even if they disturbed, handled or attacked even if they are thought to be harmless or dead are thought to be harmless or dead

- - Avoid venomous sp. as petsAvoid venomous sp. as pets - - Protective clothings, boots, socks & long Protective clothings, boots, socks & long

trousers trousers should be worn by persons at risk should be worn by persons at risk . . - - Carry light at nightCarry light at night sp. for farmers, sp. for farmers,

harvesters, fire wood collectors & for those harvesters, fire wood collectors & for those removing debris likely to conceal snakesremoving debris likely to conceal snakes

- - ImmunizationImmunization with venom toxoid to those at with venom toxoid to those at

risk risk..

Snake bite isSnake bite is: : - -A A major public health problemmajor public health problem and an and an

important cause of important cause of morbiditymorbidity and and mortality mortality , , specially in the tropicsspecially in the tropics

- -It is important occupational diseaseIt is important occupational disease - - Goverments, academic institutions, pharmaceutGoverments, academic institutions, pharmaceut agricultural bodies should encourage & sponsoragricultural bodies should encourage & sponsor clinical studies in all aspects of snake bite. clinical studies in all aspects of snake bite. - -

Education & training on snake bite should beEducation & training on snake bite should be included in the curriculum of medical schoolsincluded in the curriculum of medical schools..

- - Community education on snake bites ,firstCommunity education on snake bites ,first aid methods and preventive measures isaid methods and preventive measures is

recommendedrecommended..