ENVENOMATIONENVENOMATIONSNAKE BITE SNAKE BITE

Vikas Kesarwani MDVikas Kesarwani MDA/ProfessorA/Professor

Consultant, Pulmonary & Critical care Consultant, Pulmonary & Critical care medicine,medicine,

HIHT University, Dehradun.HIHT University, Dehradun.

EpidemiologyEpidemiology India estimates: 200,000 Snake India estimates: 200,000 Snake

bites and 15-20,000 deaths per bites and 15-20,000 deaths per year year

Males:Female::2:1.Males:Female::2:1. Majority of the bites being on Majority of the bites being on

the lower extremities. the lower extremities.

EpidemiologyEpidemiology India estimates: 200,000 Snake India estimates: 200,000 Snake

bites and 15-20,000 deaths per bites and 15-20,000 deaths per year year

Males:Female::2:1.Males:Female::2:1. Majority of the bites being on Majority of the bites being on

the lower extremities. the lower extremities. 50% of bites by venomous 50% of bites by venomous

snakes are dry bitessnakes are dry bites. that result . that result in negligible envenomation.in negligible envenomation.

Snakes : Snakes : IntroductionIntroduction

Anatomy: Anatomy:

Snakes: IntroductionSnakes: Introduction

Cold BloodedCold Blooded::No efficient thermoregulatory No efficient thermoregulatory mechanism.(no sweat glands)mechanism.(no sweat glands)

- VenomVenom has digestive enzymes has digestive enzymes which which starts working even before starts working even before the prey is swallowedthe prey is swallowed

- They They Do not chewDo not chew but swallow but swallow their prey completely. their prey completely.

India: Poisonous India: Poisonous snakessnakes

ElapidaeElapidae Cobra, KraitsCobra, Kraits NeurotoxicNeurotoxic

Viperidae Viperidae (Vipers)(Vipers)

Russell’s Vipers.,Russell’s Vipers.,Saw scaled Vipers.,Saw scaled Vipers.,Pit Vipers. Pit Vipers.

HemotoxicHemotoxic

HydrophidHydrophidaeae

Sea SnakesSea Snakes MyotoxicMyotoxic

In India, >200 species of snakes. In India, >200 species of snakes. Only 52 are poisonous.Only 52 are poisonous.

Krait and russell’s viperKrait and russell’s viper is much more toxic than that of is much more toxic than that of cobracobra

KraitKrait

CobraCobra

Pit Pit VipeVipe

rr

Rusell’s Rusell’s viperviper

Snake VenomSnake VenomCombination of Combination of

EnzymesEnzymes & & Non-EnzymaticNon-Enzymatic polypeptides. polypeptides.

-Acidic-Acidic-Sp Gravity: 1.030-1.070-Sp Gravity: 1.030-1.070-On drying-On drying Fine needle like crystals. Fine needle like crystals. -Water Soluble.-Water Soluble.--Lethal DoseLethal Dose::

CobraCobra-0.12gm, -0.12gm, KraitKrait0.06gm- 0.06gm- Russell’s VRussell’s V--0.15gm 0.15gm

DIAGNOSIS OF SNAKE BITEDIAGNOSIS OF SNAKE BITE FANG MARKS:FANG MARKS: classically, classically, twotwo puncture puncture

wounds seperated by a wounds seperated by a distance varying from 8mm to 4cm, distance varying from 8mm to 4cm, depending on the species involved.depending on the species involved.

However a However a side swipeside swipe may produce may produce only a only a singlesingle puncture,while puncture,while multiple multiple bitesbites could result in could result in numerousnumerous fang fang marks.marks.

Effects of envenomationEffects of envenomation Local effectsLocal effects Systemic effects: Systemic effects:

- Neurotoxic.- Neurotoxic.- Haemotoxic.- Haemotoxic.- Cardiotoxic. - Cardiotoxic.

Max. with Viper biteMax. with Viper bite, least with Krait bite. , least with Krait bite. Hence Hence krait bite can sometimse go unnoticedkrait bite can sometimse go unnoticed..

Clinical features:Clinical features:VENOMOUS SNAKE BITESVENOMOUS SNAKE BITES

ELAPID BITE (Krait,Cobra)ELAPID BITE (Krait,Cobra) Local featuresLocal features : : indistinct fang marks ,indistinct fang marks , burning pain, burning pain, swelling and discolouration, swelling and discolouration,

serosanguinous dischargeserosanguinous discharge

Systemic featuresSystemic featuresELAPID BITE (Krait,Cobra): NeurotoxicityELAPID BITE (Krait,Cobra): Neurotoxicity pre-paralytic stagepre-paralytic stage : : emesis,emesis, headache, headache, LOC.LOC. paralytic stageparalytic stage : ptosis, : ptosis, ophthalmoplegia ophthalmoplegia drowsiness,drowsiness, dysarthria, dysarthria, dysphagia,dysphagia, convulsions, convulsions, bulbar paralysis, bulbar paralysis, resp failure .resp failure .

Cardiac DepressionCardiac DepressionCardiogenic/Vasogenic Cardiogenic/Vasogenic ShockShock

Systolic cardiac arrest. Systolic cardiac arrest.

COBRACOBRA envenomation envenomationCardiotoxicityCardiotoxicity

VIPERID BITE (VIPERID BITE (ViperViper))

Local features:Local features: rapid rapid swellingswelling, , discolourationdiscolouration,, blisterblister formation, formation, bleedingbleeding from bite from bite

site, site, severe severe painpain

Systemic features(Haemotoxic)-Generalised bleeding manifestations. Generalised bleeding manifestations.

epistaxis,epistaxis, hemoptysis,hemoptysis, bleeding gums bleeding gums hemauria hemauria purpuric spotspurpuric spots Renal failureRenal failure

VIPERID BITE (VIPERID BITE (ViperViper))

HYDROPHID BITE (HYDROPHID BITE (sea sea snakesnake) ) MyotoxicMyotoxic

Local featuresLocal features: minimal : minimal swellingswelling and and painpain

Systemic featuresSystemic features::Myalgia, Myalgia, Muscle stiffness,Muscle stiffness,Myoglobinuria , renal tubular necrosis. Myoglobinuria , renal tubular necrosis.

ManagementManagement LocalLocal SpecificSpecific SupportiveSupportive

Management: LocalManagement: Local TourniquetTourniquet: Between wound & heart, Pressure : Between wound & heart, Pressure

adequate to adequate to occlude lymphatics onlyocclude lymphatics only, , Released for few seconds every 10 minutes. Released for few seconds every 10 minutes.

ImmobilizeImmobilize affected limb. affected limb. Elastocrepe Elastocrepe bandagebandage may be applied (except viper bites may be applied (except viper bites with lots of local reaction.)with lots of local reaction.)

Clean with Normal Saline.Clean with Normal Saline. if if bite <1hrbite <1hr old: Short old: Short skin incisionskin incision and and suctionsuction

Management: local Management: local reactionsreactions

BULLAEBULLAE - LEFT INTACT - LEFT INTACT NECROSISNECROSIS - DEBRIDEMENT - DEBRIDEMENT COMPARTMENT SYNDROMECOMPARTMENT SYNDROME - -

FASCIOTOMYFASCIOTOMY

Specific ManagementSpecific Management Anti Snake VenomAnti Snake Venom (ASV) (ASV)

- Timing - Timing - Dose- Dose- Repeat dose- Repeat dose- Hypersensitivity - Hypersensitivity

Mechanical ventilationMechanical ventilation

What is ASV?What is ASV? Antivenom is immunoglobulin purified from the serum Antivenom is immunoglobulin purified from the serum

or or plasma of a horse or sheepplasma of a horse or sheep that has been that has been immunised with the venoms of one or more species of immunised with the venoms of one or more species of snakesnake..

ASV IN INDIA: ASV IN INDIA: PolyvalentPolyvalent COBRACOBRA KRAITKRAIT RUSSEL’S VIPERRUSSEL’S VIPER SAW SCALED VIPERSAW SCALED VIPER Potency;Potency; 1 ml ASV neutralizes: 1 ml ASV neutralizes:

0.6mg 0.6mg CobraCobra, 0.45mg , 0.45mg KraitKrait, , 0.6mg 0.6mg Rusell’s VRusell’s V, , 0.45mg 0.45mg Saw scaled ViperSaw scaled Viper..--Lethal DoseLethal Dose:: CobraCobra-0.12gm, -0.12gm, KraitKrait0.06gm- 0.06gm- Russell’s VRussell’s V-0.15gm -0.15gm

Trying to capture, kill, or transport Trying to capture, kill, or transport a snake for identification a snake for identification purposes seems of little value purposes seems of little value and possibly dangerousand possibly dangerous

ASV Indication:ASV Indication: Systemic manifestaiton Systemic manifestaiton

NEUROTOXICITYNEUROTOXICITY HAEMOTOXICITYHAEMOTOXICITY NEPHROTOXICITYNEPHROTOXICITY CARDIOTOXICITYCARDIOTOXICITY RHABDOMYOLYSIS RHABDOMYOLYSIS REPEATED VOMITINGREPEATED VOMITING Others:Others:

-Local -Local swelling involving more than half of the swelling involving more than half of the bitten limb.bitten limb.--Rapid extensionRapid extension of swelling. of swelling.-Development of an -Development of an enlarged tender lymph node enlarged tender lymph node draining the bitten limbdraining the bitten limb

Timing of ASVTiming of ASV Best effects are observed Best effects are observed within four within four

hours of bite .hours of bite . Effective in Effective in symptomatic patients symptomatic patients

even 48 hours after biteeven 48 hours after bite. . Efficacious even Efficacious even 6-7 days after the 6-7 days after the

bite from vipers.bite from vipers.

Dose Dose

5 vials(50ml)

5-10 vials(50-100ml)

10-20 vials(100-200ml)

Repeat doseRepeat doseCriteria for repeating the initial dose of Criteria for repeating the initial dose of

antivenomantivenom Persistence or recurrence of Persistence or recurrence of blood blood

incoagulability after 1-2 hrincoagulability after 1-2 hr Deteriorating neurotoxic or cardiovascular Deteriorating neurotoxic or cardiovascular

signssigns after 1-2 hr after 1-2 hr Continuing absorption-Continuing absorption- due to improved due to improved

blood supply following correction of shock, blood supply following correction of shock, hypovolaemia etc hypovolaemia etc A A redistribution of venom redistribution of venom from the tissues into the vascular space.from the tissues into the vascular space.

Antivenom Antivenom reactionsreactions20% of patients, usually develop a reaction20% of patients, usually develop a reaction

Types: Types: 1.1. Early anaphylacticEarly anaphylactic reactions- within 10- reactions- within 10-

180 min180 min2.2. PyrogenicPyrogenic (endotoxin) reactions- develop (endotoxin) reactions- develop

1-2 hours 1-2 hours 3.3. Late (Late (serum sicknessserum sickness type) reactions- type) reactions-

develop 1-12 (mean 7) days.develop 1-12 (mean 7) days.

Fatal reactions have probably been Fatal reactions have probably been under-under-reported,reported, as death after snake bite is usually as death after snake bite is usually attributed to the venomattributed to the venom..

Antivenom reactions: Antivenom reactions: What to do ?What to do ?

At the earliest sign of a reaction:At the earliest sign of a reaction: Antivenom administration must be temporarily Antivenom administration must be temporarily

suspendedsuspended Adrenaline-0.1% solution, 1 in 1,000, 1 mg/ml is the Adrenaline-0.1% solution, 1 in 1,000, 1 mg/ml is the

effective treatment for early anaphylactic reactions.effective treatment for early anaphylactic reactions. IV hydrocortisone (adults 100 mg, children 2 mg/kg IV hydrocortisone (adults 100 mg, children 2 mg/kg

body weight). The corticosteroid is unlikely to act body weight). The corticosteroid is unlikely to act for several hours, but may prevent recurrent for several hours, but may prevent recurrent anaphylaxisanaphylaxis

Anti H2 antihistamines-Ranitidine – adults 50 mg, Anti H2 antihistamines-Ranitidine – adults 50 mg, children 1 mg/kg.children 1 mg/kg.

In case of circulatory collapse- start fluids, inotropes In case of circulatory collapse- start fluids, inotropes along with IV adrenalinealong with IV adrenaline

Skin testing for ASVSkin testing for ASV

Skin/conjunctival hypersensitivity Skin/conjunctival hypersensitivity testing testing does not reliably predictdoes not reliably predict early or late antivenom reactions early or late antivenom reactions and is and is not recommended.not recommended.

ASV and childrenASV and children? Dose of antivenom? Dose of antivenom Snakes inject the same dose of Snakes inject the same dose of

venom into children and adults. venom into children and adults. Children must therefore be given Children must therefore be given

exactly the same dose of antivenom exactly the same dose of antivenom as adults.as adults.

Mechanical ventilationMechanical ventilation If patient has If patient has respiratory distress or respiratory distress or

bulbar paralysis- bulbar paralysis- intubate and ventilate.intubate and ventilate. If delayed can cause aspiration or If delayed can cause aspiration or

hypoxia and cardiac arrest. hypoxia and cardiac arrest. Even if the facility for MV is not availableEven if the facility for MV is not available Ambuing can save the day.Ambuing can save the day. This helps even during transport.This helps even during transport.

SUPPORTIVE CARESUPPORTIVE CAREANTIBIOTICSANTIBIOTICSMETHYL PREDNISOLONEMETHYL PREDNISOLONEFFP,FRESH BLOOD FFP,FRESH BLOOD PREVENTION AND Rx OF HYPOTENSIONPREVENTION AND Rx OF HYPOTENSION

Summary Summary

Snake bites may be by a non-venomous snake Snake bites may be by a non-venomous snake or a dry bite. Not all snake bites require ASV.or a dry bite. Not all snake bites require ASV.

ASV is the main stayASV is the main stay in the treatment of snake in the treatment of snake bites.bites.

ASVASV must be must be initiatedinitiated if indicated at the if indicated at the earliestearliest Respiratory failureRespiratory failure can be because of different can be because of different

reasons-Neurotoxicity, shock, sepsis, ARF… reasons-Neurotoxicity, shock, sepsis, ARF… MVMV may be main stay of treatment or just may be main stay of treatment or just supportive depending on the cause of failure.supportive depending on the cause of failure.

HAEMOTOXIC ENVONOMATIONHAEMOTOXIC ENVONOMATION MILD CT < 30 MINSMILD CT < 30 MINS CLOT SIZE = 50% blood colCLOT SIZE = 50% blood col initial dose = 5 vialsinitial dose = 5 vials MODERATE CT > 30 MINSMODERATE CT > 30 MINS CLOTS ONLY SPECKLESCLOTS ONLY SPECKLES intial dose = 10 vialsintial dose = 10 vials SEVERE INCOAGULABLESEVERE INCOAGULABLE initial dose = 15 vialsinitial dose = 15 vials