SnakebiteSnakebite

Dr.Pratheeba Durairaj, M.D.,D.ADr.Pratheeba Durairaj, M.D.,D.A,,

Snake bite: an occupational Snake bite: an occupational diseasedisease

Farmers (rice)Farmers (rice) Plantation workers (rubber, coffee)Plantation workers (rubber, coffee) HerdsmenHerdsmen HuntersHunters Snake handlers (snake charmers and in snake Snake handlers (snake charmers and in snake

restaurants and traditional Chinese pharmacies)restaurants and traditional Chinese pharmacies) Fishermen and fish farmersFishermen and fish farmers Sea snake catchers (for sea snake skins, leather)Sea snake catchers (for sea snake skins, leather)

How common are snake bites?How common are snake bites? Many snake bites and even deaths from Many snake bites and even deaths from

snakebite are snakebite are not recordednot recorded. . One reason is that many snake bite victims are One reason is that many snake bite victims are

treated not in hospitals but by traditional healers.treated not in hospitals but by traditional healers. India India - No reliable national statistics are - No reliable national statistics are

available. available. In 1981, a thousand deaths were reported in In 1981, a thousand deaths were reported in

Maharashtra State. In the Burdwan district of Maharashtra State. In the Burdwan district of West Bengal 29,489 people were bitten in one West Bengal 29,489 people were bitten in one year with 1,301 deaths.year with 1,301 deaths.

It is estimated that between 35,000 and 50,000 It is estimated that between 35,000 and 50,000 people die of snake bite each year among India’s people die of snake bite each year among India’s population of 980 million.population of 980 million.

In the US: In the US: Snakebites frequently go unreported. Snakebites frequently go unreported. The national average is approximately 4 bites per The national average is approximately 4 bites per 100,000 persons. 100,000 persons.

Internationally: Internationally: No accurate international data No accurate international data exist. Most snakebites and deaths due to exist. Most snakebites and deaths due to snakebites are not reported. snakebites are not reported.

Worldwide, only about 15% of the more than Worldwide, only about 15% of the more than 3000 species of snakes are considered 3000 species of snakes are considered dangerous to humans.dangerous to humans.

The family Viperidae is the largest family of The family Viperidae is the largest family of venomous snakes, and members of this family venomous snakes, and members of this family can be found in Africa, Europe, Asia, and the can be found in Africa, Europe, Asia, and the Americas. Americas.

The family Elapidae is the next largest family The family Elapidae is the next largest family of venomous snakes. of venomous snakes.

ClassificationClassification

ClassificationClassification There are two important groups (families) of There are two important groups (families) of

venomous snakes in South East Asia venomous snakes in South East Asia Elapidae Elapidae have short permanently erect fangs have short permanently erect fangs

This family includes the cobras, king cobra, kraits, This family includes the cobras, king cobra, kraits, coral snakes and the sea snakes.coral snakes and the sea snakes.

The most important species, from a medical The most important species, from a medical point of view include the following:point of view include the following:

CobrasCobras: genus Naja: genus Naja N naja(spectaled cobra –all over in India )N naja(spectaled cobra –all over in India ) N kaouthia (monocled – West Bengal ,MP ,U.P, N kaouthia (monocled – West Bengal ,MP ,U.P,

Orissa)Orissa) N oxiana [Black cobra – northern states - N oxiana [Black cobra – northern states -

patternless]patternless] N philippinensisN philippinensis N atraN atra KKing cobra: ing cobra: Ophiophagus hannah Ophiophagus hannah

Spectacled Cobra Post synaptic NeurotoxinGood Response to Neostigmine

Short, permanently erect, fangs of a typical elapid

KRAITS (genus Bungarus)KRAITS (genus Bungarus) B caeruleus common krait [all over India ] B caeruleus common krait [all over India ]

- paired white bands & large - paired white bands & large hexagonal hexagonal scalesscales in top of the snakes in top of the snakes

B fasciatus banded krait [black & yellow band –B fasciatus banded krait [black & yellow band –W.B,M.P,A.P,BIHAR ,ORRISSA]W.B,M.P,A.P,BIHAR ,ORRISSA]

B candidus Malayan krait B candidus Malayan krait B multicinctus Chinese krait B multicinctus Chinese krait Sea snakes (important genera include Sea snakes (important genera include

Enhydrina, Lapemis and Hydrophis) Enhydrina, Lapemis and Hydrophis) Blue spotted sea snake (Hydrophis Blue spotted sea snake (Hydrophis

cyanocinctus)cyanocinctus)

Common Krait Key identification feature are PAIRED white bands.

Often enters human habitationPre Synaptic Neurotoxin.

Limited response to Neostigmine

ViperidaeViperidae

Have long fangs which are normally folded Have long fangs which are normally folded up against the upper jaw but, when the up against the upper jaw but, when the snake strikes, are erected .snake strikes, are erected .

There are two subgroups, the typical vipers There are two subgroups, the typical vipers (Viperinae) and the pit vipers (Crotalinae). (Viperinae) and the pit vipers (Crotalinae).

The Crotalinae have a special sense organ, The Crotalinae have a special sense organ, the pit organ, to detect their warm-blooded the pit organ, to detect their warm-blooded prey. This is situated between the nostril prey. This is situated between the nostril and the eyeand the eye

Russell’s vipers details of fangs

Russell's Viper

Haemotoxic venom BUT can also present neurotoxic symptoms

Although nocturnal, encountered during the day, sleeping under bushes, trees and leaf particularly coconut leaf litter

Key identification feature is the black edged almond or chain shaped marks on the back

Medically important species in South East AsiaMedically important species in South East Asia

Russell’s vipersRussell’s vipers - -Daboia russelii - Daboia russelii - [Black edged chain [Black edged chain like marking on body &white triangular marking on the like marking on body &white triangular marking on the head – throughout India]head – throughout India]

Saw-scaled or carpet vipersSaw-scaled or carpet vipers - Echis carinatus - Echis carinatus and and E E sochureki sochureki

[most parts of India except Kerala – Arrow shaped [most parts of India except Kerala – Arrow shaped mark in head & hoop like markings in flanks ]mark in head & hoop like markings in flanks ]

Pit vipersPit vipers calloselasma rhodostoma calloselasma rhodostoma malayan pit vipermalayan pit viper Hypnale hypnale Hypnale hypnale hump-nosed viperhump-nosed viper Green pit vipers or bamboo vipers (genus trimeresurus)Green pit vipers or bamboo vipers (genus trimeresurus) T albolabris T albolabris white-lipped green pit viperwhite-lipped green pit viper T gramineus T gramineus indian bamboo viperindian bamboo viper T mucrosquamatus T mucrosquamatus chinese habuchinese habu T purpureomaculatus T purpureomaculatus mangrove pit vipermangrove pit viper T stejnegeri T stejnegeri chinese bamboo viperchinese bamboo viper

Key Identification Feature- large plate scales on the head.

Encountered under bushes and leaf litter or in bushes. Haemotoxic venom. Causes Renal failureLate onset envenoming No effective anti venom

PIT VIPER

How to identify venomous snakesHow to identify venomous snakes

Some harmless snakes have evolved to Some harmless snakes have evolved to look almost identical to venomous ones. look almost identical to venomous ones.

Some of the most notorious venomous Some of the most notorious venomous snakes can be recognized by their size, snakes can be recognized by their size, shape, colour, pattern of markings, their shape, colour, pattern of markings, their behaviour and the sound they make when behaviour and the sound they make when they feel threatened.they feel threatened.

The defensive behaviour of the cobras is The defensive behaviour of the cobras is well known they rear up, spread a hood, well known they rear up, spread a hood, hiss and make repeated strikes towards hiss and make repeated strikes towards the aggressor.the aggressor.

CONTD…CONTD…

Colouring can vary a lot. Some patterns, like the Colouring can vary a lot. Some patterns, like the large white, dark rimmed spots of the Russell's large white, dark rimmed spots of the Russell's viper ,or the alternating black and yellow bands of viper ,or the alternating black and yellow bands of the banded krait are distinctive. the banded krait are distinctive.

The blowing hiss of the Russell's viper and the The blowing hiss of the Russell's viper and the grating rasp of the saw-scaled viper are warning grating rasp of the saw-scaled viper are warning and identifying sounds. and identifying sounds.

KRAIT bitesKRAIT bites : nocturnal, indoor, unprovoked & : nocturnal, indoor, unprovoked & painlesspainless

COBRA & VIPER bitesCOBRA & VIPER bites : painful : painful & accompanied by neuroparalysis,coagulopathy& accompanied by neuroparalysis,coagulopathy

The venom apparatusThe venom apparatus Venomous snakes of medical importance have a Venomous snakes of medical importance have a

pair of enlarged teeth, the fangs, at the front of pair of enlarged teeth, the fangs, at the front of their upper jaw.their upper jaw.

Venom is produced and stored in paired glands Venom is produced and stored in paired glands below the eye. It is discharged from hollow fangs below the eye. It is discharged from hollow fangs located in the upper jaw. Fangs can grow to 20 located in the upper jaw. Fangs can grow to 20 mm in large rattlesnakesmm in large rattlesnakes

These fangs contain a venom channel (like a These fangs contain a venom channel (like a hypodermic needle) or groove, along which hypodermic needle) or groove, along which venom can be introduced deep into the tissues of venom can be introduced deep into the tissues of their natural prey. their natural prey.

If a human is bitten, venom is usually injected If a human is bitten, venom is usually injected subcutaneously or intramuscularly.subcutaneously or intramuscularly.

Spitting cobras can squeeze the venom out of the Spitting cobras can squeeze the venom out of the tips of their fangs producing a fine spray directed tips of their fangs producing a fine spray directed towards the eyes of an aggressor.towards the eyes of an aggressor.

VenomVenom

Venom is mostly water. Venom is mostly water. Enzymatic proteins in venom impart its destructive Enzymatic proteins in venom impart its destructive

properties.properties. Proteases, collagenase, and arginine ester hydrolaseProteases, collagenase, and arginine ester hydrolase

have been identified in pit viper venom. have been identified in pit viper venom. Neurotoxins comprise the majority of coral snake Neurotoxins comprise the majority of coral snake

venom.venom. HyaluronidaseHyaluronidase allows rapid spread of venom through allows rapid spread of venom through

subcutaneous tissues by disrupting subcutaneous tissues by disrupting mucopolysaccharides; mucopolysaccharides;

Phospholipase A2Phospholipase A2 plays a major role in hemolysis plays a major role in hemolysis secondary to the esterolytic effect on red cell secondary to the esterolytic effect on red cell membranes and promotes muscle necrosis membranes and promotes muscle necrosis

Contd…Contd… Thrombogenic enzymesThrombogenic enzymes promote the formation of promote the formation of

a weak fibrin clot, which, in turn, activates a weak fibrin clot, which, in turn, activates plasmin and results in a consumptive plasmin and results in a consumptive coagulopathy and its hemorrhagic consequences. coagulopathy and its hemorrhagic consequences.

Enzyme concentrations vary among species, thereby Enzyme concentrations vary among species, thereby causing dissimilar envenomations. causing dissimilar envenomations.

Copperhead bites generally are limited to local tissue Copperhead bites generally are limited to local tissue destruction. destruction.

Rattlesnakes can leave impressive wounds and cause Rattlesnakes can leave impressive wounds and cause systemic toxicity.systemic toxicity.

Coral snakes may leave small wounds that later result in Coral snakes may leave small wounds that later result in respiratory failure from the typical systemic neuromuscular respiratory failure from the typical systemic neuromuscular blockade blockade

CONTD…CONTD…

ELAPID neurotoxins act at peripheral ELAPID neurotoxins act at peripheral neuromuscular junction pre /post synaptically –neuromuscular junction pre /post synaptically –prevent release of acetylcholine – prevents prevent release of acetylcholine – prevents impulse transmissionimpulse transmission

VIPER –affect coagulation pathway at several VIPER –affect coagulation pathway at several points – Russels viper –activates V,IX,X,XIII factors points – Russels viper –activates V,IX,X,XIII factors ,platelets , protein C fibrinolysis ,platelets , protein C fibrinolysis

Quantity of venom injected at a Quantity of venom injected at a bitebite

This Venom dosage per bite - is very variable - This Venom dosage per bite - is very variable - depends ondepends on

the elapsed time since the last bite the elapsed time since the last bite the degree of threat the snake feels the degree of threat the snake feels the size of the prey. the size of the prey. the species and size of the snakethe species and size of the snake the mechanical efficiency of the bitethe mechanical efficiency of the bite whether one or two fangs penetrated the skinwhether one or two fangs penetrated the skin whether there were repeated strikeswhether there were repeated strikes

The nostril pits respond to the heat emission of the The nostril pits respond to the heat emission of the prey, which may enable the snake to vary the prey, which may enable the snake to vary the amount of venom deliveredamount of venom delivered. .

Contd…Contd… A proportion of bites by venomous snakes do not result A proportion of bites by venomous snakes do not result

in the injection of sufficient venom to cause clinical in the injection of sufficient venom to cause clinical effects.effects.

About 50% of bites by malayan pit vipers and russell’s About 50% of bites by malayan pit vipers and russell’s vipers, 30% of bites by cobras and 5-10% of bites by vipers, 30% of bites by cobras and 5-10% of bites by saw-scaled vipers do not result in any symptoms or saw-scaled vipers do not result in any symptoms or signs of envenoming. signs of envenoming.

Snakes do not exhaust their store of venom, even after Snakes do not exhaust their store of venom, even after several strikes, and they are no less venomous after several strikes, and they are no less venomous after eating their prey.eating their prey.

Although large snakes tend to inject more venom than Although large snakes tend to inject more venom than smaller specimens of the same species, the venom of smaller specimens of the same species, the venom of smaller, younger vipers may be richer in some dangerous smaller, younger vipers may be richer in some dangerous components, such as those affecting haemostasis.components, such as those affecting haemostasis.

PathophysiologyPathophysiology

The local effects of venom serve as a reminder of The local effects of venom serve as a reminder of the potential systemic disruption of organ system the potential systemic disruption of organ system function. function.

Local bleeding - coagulopathies are not uncommon Local bleeding - coagulopathies are not uncommon with severe envenomations.with severe envenomations.

Local edema - increases capillary leak and Local edema - increases capillary leak and interstitial fluid in the lungs. Pulmonary mechanics interstitial fluid in the lungs. Pulmonary mechanics may be alteredmay be altered

Local cell death - increases lactic acid concentration Local cell death - increases lactic acid concentration secondary to changes in volume status and secondary to changes in volume status and requires increased minute ventilation.requires increased minute ventilation.

The effects of neuromuscular blockade result in The effects of neuromuscular blockade result in poor diaphragmatic excursion.poor diaphragmatic excursion.

Cardiac failure can result from hypotension and Cardiac failure can result from hypotension and acidosis.acidosis.

Myonecrosis raises concerns about myoglobinuria Myonecrosis raises concerns about myoglobinuria and renal damage.and renal damage.

Symptoms and signs Symptoms and signs

When venom has not been injectedWhen venom has not been injected Some people who are bitten by snakes or suspect Some people who are bitten by snakes or suspect

or imagine that they have been bitten, may or imagine that they have been bitten, may develop quite striking symptoms and signs, even develop quite striking symptoms and signs, even when no venom has been injected. This results when no venom has been injected. This results from an understandable fear of the consequences from an understandable fear of the consequences of a real venomous bite. of a real venomous bite.

Anxious people may overbreathe so that they Anxious people may overbreathe so that they develop pins and needles of the extremities, develop pins and needles of the extremities, stiffness tetany of their hands and feet and stiffness tetany of their hands and feet and dizziness. dizziness.

Others may develop vasovagal shock after the Others may develop vasovagal shock after the bite or suspected bite - faintness and collapse bite or suspected bite - faintness and collapse with profound slowing of the heart. with profound slowing of the heart.

Others may become highly agitated and irrational Others may become highly agitated and irrational and may develop a wide range of misleading and may develop a wide range of misleading symptoms. symptoms.

Contd…Contd… Another source of symptoms and signs not Another source of symptoms and signs not

caused by snake venom is first aid and traditional caused by snake venom is first aid and traditional treatments. treatments.

Constricting bands or tourniquets may cause Constricting bands or tourniquets may cause pain, swelling and congestion. pain, swelling and congestion.

Ingested herbal remedies may cause vomiting. Ingested herbal remedies may cause vomiting. Instillation of irritant plant juices into the eyes Instillation of irritant plant juices into the eyes

may cause conjunctivitis.may cause conjunctivitis. Forcible insufflations of oils into the respiratory Forcible insufflations of oils into the respiratory

tract may lead to aspiration pneumonia, tract may lead to aspiration pneumonia, bronchospasm, ruptured ear drums and bronchospasm, ruptured ear drums and pneumothorax.pneumothorax.

Incisions, cauterization, immersion in scalding Incisions, cauterization, immersion in scalding liquid and heating over a fire can result in liquid and heating over a fire can result in devastating injuries.devastating injuries.

When venom has been injected!When venom has been injected!

Early symptoms and signsEarly symptoms and signs Following the immediate pain of mechanical penetration of Following the immediate pain of mechanical penetration of

the skin by the snake’s fangs, there may be increasing local the skin by the snake’s fangs, there may be increasing local pain (burning, bursting, throbbing) at the site of the bitepain (burning, bursting, throbbing) at the site of the bite

Local swelling that gradually extends proximally up the Local swelling that gradually extends proximally up the

bitten limbbitten limb

Tender, painful enlargement of the regional lymph nodes Tender, painful enlargement of the regional lymph nodes draining the site of the bite draining the site of the bite

Bites by kraits, sea snakes and Philippine cobras may be Bites by kraits, sea snakes and Philippine cobras may be

virtually painless and may cause negligible local swelling.virtually painless and may cause negligible local swelling.

Symptoms and signs vary according to the species of snake Symptoms and signs vary according to the species of snake responsible for the bite and the amount of venom injected responsible for the bite and the amount of venom injected

Signs/Symptoms Signs/Symptoms and Potential and Potential TreatmentsTreatments

Cobra Cobra

KraitKrait Russell Russell

ViperViperSaw Scaled Saw Scaled ViperViper

Other Other VipersVipers

Local Tissue Local Tissue Damage/painDamage/pain

YESYES NONO YESYES YESYES YESYES

Ptosis/Ptosis/

NeurotoxicityNeurotoxicityYESYES YESYES YESYES NONO NONO

CoagulationCoagulation NONO NONO YESYES YESYES YESYES

Renal ProblemsRenal Problems NONO NONO YESYES NONO YESYES

Neostigmine & Neostigmine & Atropine Atropine

YESYES NO?NO? NO?NO? NONO NONO

Local symptoms and signsLocal symptoms and signs

• • Fang marks Fang marks • • Local painLocal pain• • Local bleeding Local bleeding • • BruisingBruising• • LymphangitisLymphangitis• • Lymph node enlargementLymph node enlargement• • Inflammation (swelling, redness, heat)Inflammation (swelling, redness, heat)• • Blistering Blistering • • Local infection, abscess formationLocal infection, abscess formation• • Necrosis Necrosis

Generalised Symptoms and SignsGeneralised Symptoms and Signs

GeneralGeneral Nausea, vomiting, malaise, abdominal pain, Nausea, vomiting, malaise, abdominal pain,

weakness, drowsiness, prostrationweakness, drowsiness, prostration Cardiovascular Cardiovascular (Viperidae)(Viperidae) Visual disturbances, dizziness, faintness, collapse, Visual disturbances, dizziness, faintness, collapse,

shock, hypotension, cardiac arrhythmias,shock, hypotension, cardiac arrhythmias, pulmonary oedema, conjunctiva oedema pulmonary oedema, conjunctiva oedema

Snake bite: causes of hypotension and Snake bite: causes of hypotension and shockshock

Anaphylaxis - VasodilatationAnaphylaxis - Vasodilatation CardiotoxicityCardiotoxicity HypovolaemiaHypovolaemia Antivenom reactionAntivenom reaction Respiratory failureRespiratory failure Acute pituitary adrenal insufficiency[In victims of Acute pituitary adrenal insufficiency[In victims of

Russell’s viper bites- haemorrhagic infarction of Russell’s viper bites- haemorrhagic infarction of the anterior pituitary ]the anterior pituitary ]

SepticaemiaSepticaemia

Bleeding and clotting disorders Bleeding and clotting disorders (Viperidae)(Viperidae) Bleeding from recent wounds (including fang Bleeding from recent wounds (including fang

marks ,venepunctures etc) and old partly-healed marks ,venepunctures etc) and old partly-healed woundswounds

Spontaneous systemic bleeding – from gums, epistaxisSpontaneous systemic bleeding – from gums, epistaxis Bleeding into the tears Bleeding into the tears Haemoptysis, haematemesis, rectal bleeding or Haemoptysis, haematemesis, rectal bleeding or

melaena, Haematuria, vaginal bleeding melaena, Haematuria, vaginal bleeding Bleeding into the skin and mucosae Bleeding into the skin and mucosae

(petechiae,purpura,ecchymoses) (petechiae,purpura,ecchymoses) Intracranial haemorrhageIntracranial haemorrhage

CONTD…CONTD…

Renal Renal (Viperidae, sea snakes)(Viperidae, sea snakes) Loin pain, haematuria, haemoglobinuria myoglobinuria, Loin pain, haematuria, haemoglobinuria myoglobinuria,

oliguria/anuriaoliguria/anuria Symptoms and signs of uraemiaSymptoms and signs of uraemia Endocrine Endocrine (acute pituitary/adrenal insufficiency) (acute pituitary/adrenal insufficiency)

(Russell’s viper)(Russell’s viper) Acute phase: shock, hypoglycaemiaAcute phase: shock, hypoglycaemia Chronic phase (months to years after the bite)Chronic phase (months to years after the bite)

loss of secondary sexual hair, amenorrhoea, testicular loss of secondary sexual hair, amenorrhoea, testicular atrophy, hypothyroidism etcatrophy, hypothyroidism etc

CONTD…CONTD…

CONTD…CONTD…Neurological Neurological (elapidae, (elapidae,

russell’s viper)russell’s viper) DrowsinessDrowsiness Paraesthesiae Paraesthesiae Abnormalities of taste and Abnormalities of taste and

smellsmell ““Heavy” eyelids, ptosis Heavy” eyelids, ptosis External ophthalmoplegiaExternal ophthalmoplegia Paralysis of facial muscles Paralysis of facial muscles

and other muscles and other muscles innervated by the cranial innervated by the cranial nervesnerves

Aphonia Aphonia Difficulty in swallowing Difficulty in swallowing

secretionssecretions Respiratory and Respiratory and

generalised flaccid generalised flaccid paralysisparalysis

Skeletal muscle Skeletal muscle breakdown breakdown (sea snakes, (sea snakes, russell’s viper)russell’s viper)

Generalised painGeneralised pain Stiffness and Stiffness and

Tenderness of Muscles, Tenderness of Muscles, Trismus Trismus

MyoglobinuriaMyoglobinuria Hyperkalaemia Hyperkalaemia Cardiac arrestCardiac arrest Acute renal failureAcute renal failure

ComplicationsComplications

Compartment syndrome is the most frequent Compartment syndrome is the most frequent complication of pit viper snakebites.complication of pit viper snakebites.

Local wound complications may include infection Local wound complications may include infection and skin loss.and skin loss.

Cardiovascular complications, hematologic Cardiovascular complications, hematologic complications, and pulmonary collapse may complications, and pulmonary collapse may occur.occur.

Prolonged neuromuscular blockade may occur Prolonged neuromuscular blockade may occur from coral snake envenomations.from coral snake envenomations.

Antivenin-associated complicationsAntivenin-associated complications

Immediate (anaphylaxis, type I)Immediate (anaphylaxis, type I) Result in laryngospasm, vasodilatation, and Result in laryngospasm, vasodilatation, and

leaky capillaries - deathleaky capillaries - death

Delayed (serum sickness, type iii hypersensitivity Delayed (serum sickness, type iii hypersensitivity reactions)reactions)• Serum sickness occurs 1-2 weeks after Serum sickness occurs 1-2 weeks after

administering antivenin - arthralgias, urticaria, administering antivenin - arthralgias, urticaria, and glomerulonephritis and glomerulonephritis

• Usually more than 8 vials of antivenin must be Usually more than 8 vials of antivenin must be given to produce this syndrome. given to produce this syndrome.

• Supportive care consists of antihistamines and Supportive care consists of antihistamines and steroids.steroids.

Long term complications (sequelae) of Long term complications (sequelae) of snake bitesnake bite

At the site of the bite, loss of tissue may result At the site of the bite, loss of tissue may result from sloughing or surgical debridement of from sloughing or surgical debridement of necrotic areas or amputation necrotic areas or amputation

Chronic ulceration, infection, Chronic ulceration, infection, Osteomyelitis or arthritis may persist causing Osteomyelitis or arthritis may persist causing

severe physical disability severe physical disability Malignant transformation may occur in skin Malignant transformation may occur in skin

ulcers after a number of yearsulcers after a number of years

Syndromic ApproachSyndromic Approach

It is realised that the range of activities of a particular It is realised that the range of activities of a particular venom is very wide. For example, some elapid venoms, venom is very wide. For example, some elapid venoms, such as those of Asian cobras, can cause severe local such as those of Asian cobras, can cause severe local envenoming , formerly thought to be an effect only of envenoming , formerly thought to be an effect only of viper venoms. viper venoms.

In Sri Lanka and South India, Russell’s viper venom In Sri Lanka and South India, Russell’s viper venom causes paralytic signs (ptosis etc) suggesting elapid causes paralytic signs (ptosis etc) suggesting elapid neurotoxicity, and muscle pains and dark brown urine neurotoxicity, and muscle pains and dark brown urine suggesting sea snake rhabdomyolysis. suggesting sea snake rhabdomyolysis.

There may be considerable overlap of clinical features There may be considerable overlap of clinical features caused by venoms of different speciescaused by venoms of different species

““Syndromic approach” may still be useful, especially Syndromic approach” may still be useful, especially when the snake has not been identified and only when the snake has not been identified and only monospecific antivenoms are available monospecific antivenoms are available

SYNDROME 1SYNDROME 1 Local envenoming (swelling etc) with bleeding/clotting Local envenoming (swelling etc) with bleeding/clotting

disturbances disturbances = Viperidae (all species)= Viperidae (all species)

SYNDROME 2SYNDROME 2 Local envenoming (swelling etc) with bleeding/clotting Local envenoming (swelling etc) with bleeding/clotting

disturbances,disturbances, shock or renal failureshock or renal failure = Russell’s viper and possibly saw-scaled viper = Russell’s viper and possibly saw-scaled viper

- Echis species - in some areas)- Echis species - in some areas) with conjunctival oedema (chemosis) and acute pituitary with conjunctival oedema (chemosis) and acute pituitary

insufficiency insufficiency = Russell’s viper, Burma= Russell’s viper, Burma with ptosis, external ophthalmoplegia, facial paralysis etc with ptosis, external ophthalmoplegia, facial paralysis etc

and dark & brown urineand dark & brown urine = Russell’s viper, Sri Lanka and South India= Russell’s viper, Sri Lanka and South India

SYNDROME 3SYNDROME 3 Local envenoming (swelling etc) with paralysisLocal envenoming (swelling etc) with paralysis = cobra or king cobra= cobra or king cobra

SYNDROME 4SYNDROME 4 Paralysis with minimal or no local envenomingParalysis with minimal or no local envenoming Bite on land while sleeping, outside the Philippines Bite on land while sleeping, outside the Philippines = krait= krait in the Philippines in the Philippines = cobra(= cobra(Naja philippinensisNaja philippinensis)) Bite in the sea Bite in the sea = sea snake= sea snake

SYNDROME 5SYNDROME 5 Paralysis with dark brown urine and renal failureParalysis with dark brown urine and renal failure Bite on land (with bleeding/clotting disturbance) Bite on land (with bleeding/clotting disturbance) = =

Russell’s viper, SriLanka/South IndiaRussell’s viper, SriLanka/South India Bite in the sea (no bleeding/clotting disturbances) Bite in the sea (no bleeding/clotting disturbances) = sea = sea

snakesnake Chronic renal failure occurs after bilateral cortical necrosis Chronic renal failure occurs after bilateral cortical necrosis

(Russell’s viper bites) and chronic panhypopituitarism or (Russell’s viper bites) and chronic panhypopituitarism or diabetes insipidus after Russell’s viper bites in Myanmar diabetes insipidus after Russell’s viper bites in Myanmar and South Indiaand South India

Management of snake biteManagement of snake bite

First aid treatmentFirst aid treatment

Transport to hospitalTransport to hospital Rapid clinical assessment and resuscitationRapid clinical assessment and resuscitation Detailed clinical assessment and species Detailed clinical assessment and species

diagnosisdiagnosis Investigations/laboratory testsInvestigations/laboratory tests Antivenom treatmentAntivenom treatment Observation of the response to Observation of the response to

antivenom:decision about the need for further antivenom:decision about the need for further dose(s) of antivenomdose(s) of antivenom

Supportive/ancillary treatmentSupportive/ancillary treatment Treatment of the bitten partTreatment of the bitten part RehabilitationRehabilitation Treatment of chronic complicationsTreatment of chronic complications

Aims of first aidAims of first aid

Attempt to retard systemic absorption of venomAttempt to retard systemic absorption of venom Preserve life and prevent complications before Preserve life and prevent complications before

the patient can receive medical care(at a the patient can receive medical care(at a dispensary or hospital)dispensary or hospital)

Control distressing or dangerous early symptoms Control distressing or dangerous early symptoms of envenomingof envenoming

Arrange the transport of the patient to a place Arrange the transport of the patient to a place where they can receive medical carewhere they can receive medical care

ABOVE ALL, DO NO HARMABOVE ALL, DO NO HARM!!

FIRST AID –CONTDFIRST AID –CONTD…… Unfortunately, most of the traditional, popular, Unfortunately, most of the traditional, popular,

available and affordable first aid methods have available and affordable first aid methods have proved to be useless or even frankly dangerous. proved to be useless or even frankly dangerous.

Making local incisions or pricks/punctures Making local incisions or pricks/punctures (“tattooing”) at the site of the bite or in the (“tattooing”) at the site of the bite or in the bitten limbbitten limb

Attempts to suck the venom out of the wound Attempts to suck the venom out of the wound Use of (black) snake stonesUse of (black) snake stones Tying tight bands [tourniquets) around the Tying tight bands [tourniquets) around the

limblimb Electric shockElectric shock Topical application of chemicals ,herbs or ice Topical application of chemicals ,herbs or ice

packs.packs.

Tight (arterial) tourniquets are not Tight (arterial) tourniquets are not recommended!recommended!

To be effective, these had to be applied around the To be effective, these had to be applied around the upper part of the limb, so tightly that the peripheral upper part of the limb, so tightly that the peripheral pulse was occluded. pulse was occluded.

This method was extremely painful and very This method was extremely painful and very dangerous if the tourniquet was left on for too long dangerous if the tourniquet was left on for too long (more than about 40 minutes), as the limb might be (more than about 40 minutes), as the limb might be damaged by ischaemia- damaged by ischaemia- gangrenous limbsgangrenous limbs

Pressure immobilisation is recommended for Pressure immobilisation is recommended for bites by neurotoxic elapid snakes, including sea bites by neurotoxic elapid snakes, including sea snakes but should not be used for viper bites snakes but should not be used for viper bites because of the danger of increasing the local because of the danger of increasing the local effects of the necrotic venom.effects of the necrotic venom.

Tight (arterial) tourniquets are not Tight (arterial) tourniquets are not recommended- WHY?recommended- WHY?

Confining this toxin in a smaller area, by use of compression Confining this toxin in a smaller area, by use of compression techniques creates a greater risk of serious local damage. techniques creates a greater risk of serious local damage.

When the tourniquet is removed there is the problem of the When the tourniquet is removed there is the problem of the venom rapidly entering the system and causing respiratory venom rapidly entering the system and causing respiratory failure in the case of neurotoxic bitesfailure in the case of neurotoxic bites

The Viper’s venom contains pro-coagulant enzymes which The Viper’s venom contains pro-coagulant enzymes which cause the blood to clot. In the small space below the cause the blood to clot. In the small space below the tourniquet the venom has a greater chance of causing a tourniquet the venom has a greater chance of causing a clot. When the tourniquet is released the clot will rapidly clot. When the tourniquet is released the clot will rapidly enter the body and can cause embolism and death.enter the body and can cause embolism and death.

Lastly, there has been a great deal of research showing that Lastly, there has been a great deal of research showing that tourniquets DO NOT stop venom from entering the body tourniquets DO NOT stop venom from entering the body

Recommended first aid methodsRecommended first aid methods

• • Reassure the victim who may be very anxiousReassure the victim who may be very anxious

• • Immobilise the bitten limb with a splint or sling Immobilise the bitten limb with a splint or sling (any movement or muscular contraction (any movement or muscular contraction increases absorption of venom into the increases absorption of venom into the bloodstream and lymphatics)bloodstream and lymphatics)

• • Consider pressure-immobilisation for some elapid Consider pressure-immobilisation for some elapid bitesbites

• • Avoid any interference with the bite wound as this Avoid any interference with the bite wound as this may introduce infection,increase absorption of may introduce infection,increase absorption of the venom and increase local bleedingthe venom and increase local bleeding

Pressure immobilisation methodPressure immobilisation method

An elasticated, stretchy, crepe An elasticated, stretchy, crepe Bandage,approximately 10 cm wide and at Bandage,approximately 10 cm wide and at least 4.5 metres long should be used. least 4.5 metres long should be used.

If that it not available, any long strips of If that it not available, any long strips of material can be used. material can be used.

The bandage is bound firmly around the entire The bandage is bound firmly around the entire bitten limb, starting distally around the fingers bitten limb, starting distally around the fingers or toes and moving proximally, to include a or toes and moving proximally, to include a rigid splint. rigid splint.

The bandage is bound as tightly as for a The bandage is bound as tightly as for a sprained ankle, but not so tightly that the sprained ankle, but not so tightly that the peripheral pulse (radial, posterior tibial, peripheral pulse (radial, posterior tibial, dorsalis pedis) is occluded or that a finger dorsalis pedis) is occluded or that a finger cannot easily be slipped between its layers cannot easily be slipped between its layers

Rapid clinical assessment and Rapid clinical assessment and resuscitationresuscitation

AAirway, respiratory movements (irway, respiratory movements (BBreathing) and arterial pulse reathing) and arterial pulse ((CCirculation) must be checked immediately. irculation) must be checked immediately.

The level of consciousness must be assessed.The level of consciousness must be assessed. Urgent Resuscitation is needed inUrgent Resuscitation is needed in a) Profound hypotension and shock resulting from direct a) Profound hypotension and shock resulting from direct

cardiovascular effects of the venom or secondary effects such cardiovascular effects of the venom or secondary effects such as hypovolaemia or hemorrhagic shock.as hypovolaemia or hemorrhagic shock.

b) Terminal respiratory failure from progressive neurotoxic b) Terminal respiratory failure from progressive neurotoxic envenoming that has led to paralysis of the respiratory envenoming that has led to paralysis of the respiratory muscles.muscles.

c) Sudden deterioration or rapid development of severe c) Sudden deterioration or rapid development of severe systemic envenoming following the release of a tight systemic envenoming following the release of a tight tourniquet or compression bandage tourniquet or compression bandage

d) Cardiac arrest precipitated by hyperkalaemia resulting d) Cardiac arrest precipitated by hyperkalaemia resulting from skeletal muscle breakdown (rhabdomyolysis) after sea from skeletal muscle breakdown (rhabdomyolysis) after sea snake bite.snake bite.

HistoryHistory Obtain a description of the snake or capture it, if possible, to Obtain a description of the snake or capture it, if possible, to

determine its color, pattern, or the existence of a rattle.determine its color, pattern, or the existence of a rattle. Most snakes remain within 20 feet after biting.Most snakes remain within 20 feet after biting. Assess the timing of events and onset of symptoms. Inquire Assess the timing of events and onset of symptoms. Inquire

about the time the bite occurred and details about the onset of about the time the bite occurred and details about the onset of pain. Early and intense pain implies significant envenomation.pain. Early and intense pain implies significant envenomation.

Local swelling, pain, and paresthesias may be present.Local swelling, pain, and paresthesias may be present.

Systemic symptoms include nausea, syncope, and difficulty Systemic symptoms include nausea, syncope, and difficulty swallowing or breathing.swallowing or breathing.

Determine history of prior exposure to antivenin or snakebite.Determine history of prior exposure to antivenin or snakebite. history of allergies to medicines history of allergies to medicines

history of co morbid conditions or medications (eg, history of co morbid conditions or medications (eg, aspirin, anticoagulants such as warfarin or GPIIb/IIIa aspirin, anticoagulants such as warfarin or GPIIb/IIIa inhibitors, beta-blockers).inhibitors, beta-blockers).

Physical ExaminationPhysical Examination Vital signs, airway, breathing, circulationVital signs, airway, breathing, circulation Fang marksFang marks or scratches (determine coral snake bite or scratches (determine coral snake bite

pattern by expressing blood from the suspected wound)pattern by expressing blood from the suspected wound) Local tissue destructionLocal tissue destruction

• Soft pitting edema that generally develops over 6-12 Soft pitting edema that generally develops over 6-12 hours but may start within 5 minuteshours but may start within 5 minutes

• BullaeBullae• StreakingStreaking• Erythema or discolorationErythema or discoloration• ContusionsContusions

Systemic toxicitySystemic toxicity• HypotensionHypotension• Petechiae, epistaxis, hemoptysisPetechiae, epistaxis, hemoptysis• Paresthesias and dysthesias - Forewarn neuromuscular Paresthesias and dysthesias - Forewarn neuromuscular

blockade and respiratory distress (more common with blockade and respiratory distress (more common with coral snakes)coral snakes)

Early clues that a patient has severe Early clues that a patient has severe envenomingenvenoming

• • Snake identified as a very dangerous oneSnake identified as a very dangerous one• • Rapid early extension of local swelling from the Rapid early extension of local swelling from the

site of the bitesite of the bite• • Tender enlargement of local lymph nodes, Tender enlargement of local lymph nodes,

indicating spread of venom in the lymphatic indicating spread of venom in the lymphatic systemsystem

• • Systemic symptoms: collapse (hypotension, shock) Systemic symptoms: collapse (hypotension, shock) nausea, vomiting,diarrhoeanausea, vomiting,diarrhoea severe headachesevere headache “ “heaviness” of the eyelids heaviness” of the eyelids inappropriate drowsinessinappropriate drowsiness early ptosis/ophthalmoplegiaearly ptosis/ophthalmoplegia• • Early spontaneous systemic bleedingEarly spontaneous systemic bleeding• • Passage of dark brown urinePassage of dark brown urine

Lab StudiesLab Studies

CBC with manual differential and peripheral CBC with manual differential and peripheral blood smearblood smear

Prothrombin time and activated partial Prothrombin time and activated partial thromboplastin time, international normalized thromboplastin time, international normalized ratio (INR).ratio (INR).

Fibrinogen and split productsFibrinogen and split products Type and crossType and cross Blood chemistries - electrolytes, BUN, creatinineBlood chemistries - electrolytes, BUN, creatinine Urinalysis for myoglobinuriaUrinalysis for myoglobinuria Arterial blood gas determinations for patients Arterial blood gas determinations for patients

with systemic symptomswith systemic symptoms

CONTD…CONTD…

Imaging Studies:Imaging Studies: Baseline chest radiograph in patients with pulmonary Baseline chest radiograph in patients with pulmonary

edemaedema Plain radiograph to rule out retained fangPlain radiograph to rule out retained fang Other Tests:Other Tests: Compartmental pressures may need to Compartmental pressures may need to

be measured.be measured. Measurement of compartmental pressures is Measurement of compartmental pressures is

indicated when significant swelling is present, pain is indicated when significant swelling is present, pain is out of proportion to exam, and if paresthesias are out of proportion to exam, and if paresthesias are present in the affected limb.present in the affected limb.

20 minute whole blood clotting test 20 minute whole blood clotting test (20WBCT)(20WBCT)

This very useful and informative bedside test requires very This very useful and informative bedside test requires very little skill and only one piece of apparatus - a new, clean, little skill and only one piece of apparatus - a new, clean, dry, glass vessel (tube or bottle).dry, glass vessel (tube or bottle).

• • Place a few ml of freshly sampled venous blood in a small Place a few ml of freshly sampled venous blood in a small glass vesselglass vessel

• • Leave undisturbed for 20 minutes at ambient temperatureLeave undisturbed for 20 minutes at ambient temperature• • Tip the vessel onceTip the vessel once• • If the blood is still liquid (unclotted) and runs out, the patient If the blood is still liquid (unclotted) and runs out, the patient

has hypofibrinogenaemia (“incoagulable blood”) as a result has hypofibrinogenaemia (“incoagulable blood”) as a result of venom-induced consumption coagulopathyof venom-induced consumption coagulopathy

• • In the South East Asian region, incoagulable blood is In the South East Asian region, incoagulable blood is diagnostic of a viper bite and rules out an elapid bitediagnostic of a viper bite and rules out an elapid bite

• • Warning! If the vessel used for the test is not made of Warning! If the vessel used for the test is not made of ordinary glass, or if it has been used before and ordinary glass, or if it has been used before and cleaned with detergent, its wall may not stimulatecleaned with detergent, its wall may not stimulate

clotting of the blood sample in the usual way and test clotting of the blood sample in the usual way and test will be invalid will be invalid

Every 30 minutes for the first 4hours *hourly after Every 30 minutes for the first 4hours *hourly after thatthat

Haemoglobin concentration/haematocritHaemoglobin concentration/haematocrit: : a transient increase indicates a transient increase indicates

haemoconcentration resulting from a generalised haemoconcentration resulting from a generalised increase in capillary permeability - in Russell’s increase in capillary permeability - in Russell’s viper biteviper bite

a decrease reflecting blood loss or intravascular a decrease reflecting blood loss or intravascular haemolysis - Indian and Sri Lankan Russell’s viper haemolysis - Indian and Sri Lankan Russell’s viper bitebite

Platelet countPlatelet count: decreased in victims of viper bites.: decreased in victims of viper bites. White blood cell countWhite blood cell count: an early neutrophil : an early neutrophil

leucocytosis is evidence of systemic envenoming leucocytosis is evidence of systemic envenoming from any species.from any species.

Blood filmBlood film: fragmented red cells (“helmet cell”, : fragmented red cells (“helmet cell”, schistocytes) are seen when there is schistocytes) are seen when there is microangiopathic haemolysis.microangiopathic haemolysis.

Plasma/serum Plasma/serum may be pinkish or brownish if there may be pinkish or brownish if there is gross haemoglobinaemia or myoglobinaemia.is gross haemoglobinaemia or myoglobinaemia.

Biochemical abnormalitiesBiochemical abnormalities

Elevated AminotransferasesElevated Aminotransferases and muscle enzymes and muscle enzymes (creatine kinase, aldolase etc) in severe local (creatine kinase, aldolase etc) in severe local damage or generalized muscle damage (Srilankan damage or generalized muscle damage (Srilankan and South Indian Russell's viper bites, sea and South Indian Russell's viper bites, sea snakebites). snakebites).

Slight increases in other Slight increases in other serum enzymesserum enzymes - Mild - Mild hepatic dysfunctionhepatic dysfunction

Elevated BilirubinElevated Bilirubin - in massive extravasation of - in massive extravasation of blood.blood.

Creatinine, urea or blood urea nitrogenCreatinine, urea or blood urea nitrogen levels - levels - raised in the renal failure of russell’s viper and saw-raised in the renal failure of russell’s viper and saw-scaled viper bites and sea snake bites. scaled viper bites and sea snake bites.

Early Early hyperkalaemiahyperkalaemia - in extensive rhabdomyolysis - in extensive rhabdomyolysis in sea snake bites. in sea snake bites.

BicarbonateBicarbonate will be low in renalfailure will be low in renalfailure

Arterial blood gases and pHArterial blood gases and pH may show may show evidence of respiratory failure (neurotoxic evidence of respiratory failure (neurotoxic envenoming) and acidaemia envenoming) and acidaemia

DesaturationDesaturation:: patients with respiratory failure patients with respiratory failure or shock using a finger oximeter.or shock using a finger oximeter.

Urine examinationUrine examination: the urine should be tested : the urine should be tested by dipsticks for blood/haemoglobin/myoglobin. by dipsticks for blood/haemoglobin/myoglobin. Haemoglobin and myoglobin can be separated by Haemoglobin and myoglobin can be separated by immunoassays but there is no easy or reliable immunoassays but there is no easy or reliable test. Microscopy will confirm whether there are test. Microscopy will confirm whether there are erythrocytes in the urine.erythrocytes in the urine.

Red cell casts indicate glomerular bleeding. Red cell casts indicate glomerular bleeding. Massive proteinuria is an early sign of the Massive proteinuria is an early sign of the generalised increase in capillary permeabilitygeneralised increase in capillary permeability

GRADES- MILD, MODERATE, OR SEVEREGRADES- MILD, MODERATE, OR SEVERE Mild envenomationMild envenomation - local pain, edema, no signs of systemic - local pain, edema, no signs of systemic

toxicity and normal lab values.toxicity and normal lab values.Moderate envenomationModerate envenomation - severe local pain - severe local pain• edema larger than 12 inches surrounding the wound edema larger than 12 inches surrounding the wound • systemic toxicity including nausea, vomiting systemic toxicity including nausea, vomiting • alterations in lab values (fallen hematocrit or platelet alterations in lab values (fallen hematocrit or platelet

values). values). Severe envenomationSevere envenomation • generalized petechiae, ecchymosis generalized petechiae, ecchymosis • blood-tinged sputumblood-tinged sputum• hypotension, hypoperfusionhypotension, hypoperfusion• renal dysfunction renal dysfunction • changes in prothrombin time and activated partial changes in prothrombin time and activated partial

thromboplastin time, and other abnormal tests defining thromboplastin time, and other abnormal tests defining consumptive coagulopathy. consumptive coagulopathy.

Grading envenomations is a dynamic processGrading envenomations is a dynamic process. Over . Over several hours, an initially mild syndrome may progress to a several hours, an initially mild syndrome may progress to a moderate or even severe reaction.moderate or even severe reaction.

Medical CareMedical Care Treatment is based on the severity of envenomation; it is Treatment is based on the severity of envenomation; it is

divided into field care and hospital management. divided into field care and hospital management. Field care Field care

• Reassure the patient to preclude hysteria during the Reassure the patient to preclude hysteria during the implementation of ABCs. implementation of ABCs.

• Monitor vital signs and establish at least 1 large bore Monitor vital signs and establish at least 1 large bore intravenous and crystalloid infusion. intravenous and crystalloid infusion.

• Administer oxygen therapy. Administer oxygen therapy. • Restrict activity and immobilize the affected area Restrict activity and immobilize the affected area

(commonly an extremity); keep walking to a minimum. (commonly an extremity); keep walking to a minimum. • Negative-pressure suctioning devices offer some benefit if Negative-pressure suctioning devices offer some benefit if

used within several minutes of envenomation. used within several minutes of envenomation. Do not make Do not make an incision in the field. an incision in the field.

• Immediately transfer to definitive care. Immediately transfer to definitive care. • Do not give antivenin in the field.Do not give antivenin in the field.

CONTD…CONTD… Hospital careHospital care

• Physicians who have little experience treating Physicians who have little experience treating snakebites frequently see patients. snakebites frequently see patients.

• Regional centers often have more experience Regional centers often have more experience in the care of snakebite victims. Surgical in the care of snakebite victims. Surgical evaluation for envenomation is paramount. evaluation for envenomation is paramount.

• Definitive treatment includes reviewing the Definitive treatment includes reviewing the ABCs and evaluating the patient for signs of ABCs and evaluating the patient for signs of shock (eg, tachypnea, tachycardia, dry pale shock (eg, tachypnea, tachycardia, dry pale skin, mental status changes, hypotension).skin, mental status changes, hypotension).

Surgical CareSurgical Care Surgical assessment follows the injury site and Surgical assessment follows the injury site and

assess for the development of compartment assess for the development of compartment syndrome.syndrome.• Fasciotomy is not indicated in every bite, only Fasciotomy is not indicated in every bite, only

for those patients with objective evidence of for those patients with objective evidence of elevated compartment pressures.elevated compartment pressures.

• Liberal use of the Stryker pressure monitor is Liberal use of the Stryker pressure monitor is warranted. Tissue injury after compartment warranted. Tissue injury after compartment syndrome is not reversible but is preventablesyndrome is not reversible but is preventable

Make serial evaluations for further grading and to Make serial evaluations for further grading and to rule out compartment syndrome. Depending on rule out compartment syndrome. Depending on clinical scenarios, measure compartment clinical scenarios, measure compartment pressures every 30-120 minutes. Fasciotomy is pressures every 30-120 minutes. Fasciotomy is indicated for pressures greater than 30-40 mm indicated for pressures greater than 30-40 mm Hg. Hg.

Compartmental syndromes and Compartmental syndromes and fasciotomyfasciotomy

Clinical featuresClinical features Disproportionately severe painDisproportionately severe pain Weakness of intracompartmental musclesWeakness of intracompartmental muscles Pain on passive stretching of intracompartmental Pain on passive stretching of intracompartmental

musclesmuscles Hypoaesthesia of areas of skin supplied by Hypoaesthesia of areas of skin supplied by

nerves running through the compartmentnerves running through the compartment Obvious tenseness of the compartment on Obvious tenseness of the compartment on

palpationpalpation

CONTD…CONTD… The most reliable test is to measure The most reliable test is to measure

intracompartmental pressure directly through a intracompartmental pressure directly through a cannula introduced into the compartment and cannula introduced into the compartment and connected to a pressure transducer or connected to a pressure transducer or manometermanometer

Intracompartmental pressures exceeding 40 Intracompartmental pressures exceeding 40 mmHg (less in children) may carry a risk of mmHg (less in children) may carry a risk of ischaemic necrosis ischaemic necrosis

Early treatment with antivenom remains the Early treatment with antivenom remains the best way of preventing irreversible muscle best way of preventing irreversible muscle damagedamage

Criteria for fasciotomy in snake-bitten limbsCriteria for fasciotomy in snake-bitten limbs Haemostatic abnormalities have been Haemostatic abnormalities have been

corrected corrected Clinical evidence of an intracompartmental Clinical evidence of an intracompartmental

syndromesyndrome Intracompartmental pressure >40 mmHg (in Intracompartmental pressure >40 mmHg (in

adults)adults)

PharmacotherapyPharmacotherapy

The goals of pharmacotherapy are to The goals of pharmacotherapy are to neutralize the toxin, to reduce morbidity neutralize the toxin, to reduce morbidity and to prevent complications and to prevent complications

AntibioticsAntibiotics ImmunizationsImmunizations -- Snakes do not harbor -- Snakes do not harbor

Clostridium tetaniClostridium tetani in their mouths, but in their mouths, but bites may carry other bacteria, especially bites may carry other bacteria, especially gram-negative species. gram-negative species.

Tetanus prophylaxisTetanus prophylaxis recommended if recommended if patient not immunized. patient not immunized.

AntiveninAntivenin

What is antivenom?What is antivenom?

Antivenom is immunoglobulin (usually the Antivenom is immunoglobulin (usually the enzyme refined F(ab)2 fragment of IgG] purified enzyme refined F(ab)2 fragment of IgG] purified from the serum or plasma of a horse or sheep from the serum or plasma of a horse or sheep that has been immunised with the venoms of one that has been immunised with the venoms of one or more species of snake.or more species of snake.

“ “Specific” antivenom, implies that the antivenom Specific” antivenom, implies that the antivenom has been raised against the venom of the snake has been raised against the venom of the snake that has bitten the patient and that it can that has bitten the patient and that it can therefore be expected to contain specific therefore be expected to contain specific antibody that will neutralise that particular antibody that will neutralise that particular venom.venom.

Monovalent or monospecific antivenom Monovalent or monospecific antivenom neutralises the venom of only one species of neutralises the venom of only one species of snake.snake.

Polyvalent or polyspecific antivenom neutralises Polyvalent or polyspecific antivenom neutralises the venoms of several different species of snakes.the venoms of several different species of snakes.

CONTD…CONTD…

For example, Haffkine, Kasauli, Serum Institute of For example, Haffkine, Kasauli, Serum Institute of India and Bengal “polyvalent anti-snake venom India and Bengal “polyvalent anti-snake venom serum” is raised in horses using the venoms of serum” is raised in horses using the venoms of the four most important venomous snakes in the four most important venomous snakes in India (Indian cobra, India (Indian cobra, Naja najaNaja naja; Indian krait, ; Indian krait, Bungarus caeruleusBungarus caeruleus; Russell’s viper,; Russell’s viper,Daboia Daboia russeliirusselii; saw-scaled viper, ; saw-scaled viper, Echis carinatusEchis carinatus). ).

Antibodies raised against the venom of one Antibodies raised against the venom of one species may have cross-neutralising activity species may have cross-neutralising activity against other venoms, usually from closely against other venoms, usually from closely related species. This is known as paraspecific related species. This is known as paraspecific activity. activity.

CONTD…CONTD…

Antivenom treatment carries a risk of Antivenom treatment carries a risk of severe adverse reactions and in most severe adverse reactions and in most countries it is costly and may be in limited countries it is costly and may be in limited supply. It should therefore be used only in supply. It should therefore be used only in patients in whom the benefits of antivenom patients in whom the benefits of antivenom treatment are considered to exceed the treatment are considered to exceed the risks.risks.

How long after the bite can antivenom be How long after the bite can antivenom be expected to be effective?expected to be effective?

Antivenom treatment should be given as soon as Antivenom treatment should be given as soon as it is indicated. It may reverse systemic it is indicated. It may reverse systemic envenoming even when this has persisted for envenoming even when this has persisted for several days or, in the case of haemostatic several days or, in the case of haemostatic abnormalities, for two or more weeks.abnormalities, for two or more weeks.

However, when there are signs of local However, when there are signs of local envenoming, envenoming, without without systemic envenoming, systemic envenoming, antivenom will be effective only if it can be given antivenom will be effective only if it can be given within the first few hours after the bite.within the first few hours after the bite.

Indications for AntivenomIndications for AntivenomAntivenom treatment is recommended if and when Antivenom treatment is recommended if and when

a patient with proven or suspected snake a patient with proven or suspected snake develops one or more of the following signsdevelops one or more of the following signs

Systemic envenomingSystemic envenoming Haemostatic abnormalities:Haemostatic abnormalities: spontaneous systemic bleeding (spontaneous systemic bleeding (clinicalclinical)) coagulopathy (coagulopathy (20WBCT or other laboratory20WBCT or other laboratory) ) thrombocytopenia (<100 x 109/litre) (thrombocytopenia (<100 x 109/litre) (laboratorylaboratory)) Neurotoxic signs:Neurotoxic signs: ptosis, external ophthalmoplegia, ptosis, external ophthalmoplegia,

paralysis etc (paralysis etc (clinicalclinical)) Cardiovascular abnormalitiesCardiovascular abnormalities: hypotension, shock, cardiac : hypotension, shock, cardiac

arrhythmia (arrhythmia (clinicalclinical),abnormal ECG),abnormal ECG Acute renal failureAcute renal failure: : oliguria/anuria, rising blood creatinine/ oliguria/anuria, rising blood creatinine/

urea, (urea, (Haemoglobin-/myoglobin-uria:Haemoglobin-/myoglobin-uria:) dark brown urine, ) dark brown urine, other evidence of intravascular haemolysis or generalised other evidence of intravascular haemolysis or generalised rhabdomyolysis (muscle aches and pains, hyperkalaemia)rhabdomyolysis (muscle aches and pains, hyperkalaemia)

CONTD…CONTD…

Local envenomingLocal envenoming Local swelling involving more than half of Local swelling involving more than half of

the bitten limb (in the absence of athe bitten limb (in the absence of a tourniquet) tourniquet) Swelling after bites on the digits (toes and Swelling after bites on the digits (toes and

especially fingers)especially fingers) Rapid extension of swelling (for example Rapid extension of swelling (for example

beyond the wrist or ankle within a fewbeyond the wrist or ankle within a few hours of bites on the hands or feet)hours of bites on the hands or feet) Development of an enlarged tender Development of an enlarged tender

lymph node draining the bitten limb lymph node draining the bitten limb

Contraindications to antivenomContraindications to antivenom

There is no absolute contraindication to There is no absolute contraindication to antivenom treatment antivenom treatment

Patients who have reacted to horse (equine) or Patients who have reacted to horse (equine) or sheep (ovine) serum in the past (for example sheep (ovine) serum in the past (for example after treatment with equine Anti-tetanus serum, after treatment with equine Anti-tetanus serum, equine anti-rabies serum or equine or ovine equine anti-rabies serum or equine or ovine antivenom) antivenom)

Those with a strong history of atopic diseases Those with a strong history of atopic diseases (especially severe asthma) should be given (especially severe asthma) should be given antivenom only if they have signs of systemic antivenom only if they have signs of systemic envenoming.envenoming.

Prophylaxis in high risk patientsProphylaxis in high risk patients

High risk patients may be pre-treated High risk patients may be pre-treated empirically empirically with with

Subcutaneous epinephrineSubcutaneous epinephrine

Intravenous antihistamines (both anti-H1, such Intravenous antihistamines (both anti-H1, such as promethazine , anti- H2, such as cimetidine or as promethazine , anti- H2, such as cimetidine or ranitidine) ranitidine)

Corticosteroid.Corticosteroid. In asthmatic patients, prophylactic use of an In asthmatic patients, prophylactic use of an

inhaled adrenergic ß2 agonist such as salbutamol inhaled adrenergic ß2 agonist such as salbutamol may prevent bronchospasmmay prevent bronchospasm

Selection of antivenomSelection of antivenom Antivenom should be given only if its stated Antivenom should be given only if its stated

range of specificity includes the species known or range of specificity includes the species known or thought to have been responsible for the bite.thought to have been responsible for the bite.

Liquid antivenoms that have become opaque Liquid antivenoms that have become opaque should not be used as precipitation of protein should not be used as precipitation of protein indicates loss of activity and an increased riskindicates loss of activity and an increased risk

of reactions.of reactions. If the biting species is known, the ideal treatment If the biting species is known, the ideal treatment

is with a monospecific/monovalent antivenom, as is with a monospecific/monovalent antivenom, as this involves administration of a lower dose of this involves administration of a lower dose of antivenom protein than with a polyspecific/ antivenom protein than with a polyspecific/ polyvalent antivenoms.polyvalent antivenoms.

Polyspecific/polyvalent antivenoms are preferred Polyspecific/polyvalent antivenoms are preferred in many countries because of the difficulty in in many countries because of the difficulty in identifying species responsible for bites. identifying species responsible for bites.

Administration of antivenomAdministration of antivenom Freeze-dried (lyophilised) antivenoms are Freeze-dried (lyophilised) antivenoms are

reconstituted, usually with 10 ml of sterile water. reconstituted, usually with 10 ml of sterile water. The freeze-dried protein may be difficult to The freeze-dried protein may be difficult to dissolvedissolve

Skin and conjunctival “hypersensitivity” tests Skin and conjunctival “hypersensitivity” tests may reveal IgE mediated Type I hypersensitivity may reveal IgE mediated Type I hypersensitivity to horse or sheep proteins but do not Predict the to horse or sheep proteins but do not Predict the large majority of early (anaphylactic) or late large majority of early (anaphylactic) or late (serum sickness type) antivenom reactions. Since (serum sickness type) antivenom reactions. Since they may delay treatment and can in themselves they may delay treatment and can in themselves be sensitizing, be sensitizing, these tests should not be used.these tests should not be used.

Epinephrine should always be drawn up in Epinephrine should always be drawn up in readiness before antivenom is administered.readiness before antivenom is administered.

Antivenom should be given by the intravenous Antivenom should be given by the intravenous route whenever possibleroute whenever possible..

Intravenous injectionIntravenous injection Intravenous “push” injectionIntravenous “push” injection: reconstituted freeze-: reconstituted freeze-

dried antivenom or neat liquid antivenom is given by dried antivenom or neat liquid antivenom is given by slow intravenous injection (not more than 2 slow intravenous injection (not more than 2 ml/minute). This method has the advantage that the ml/minute). This method has the advantage that the doctor/nurse/dispenser giving the antivenom must doctor/nurse/dispenser giving the antivenom must remain with the patient during the time when some remain with the patient during the time when some early reactions may develop. It is also economical, early reactions may develop. It is also economical, saving the use of intravenous fluids, giving sets, saving the use of intravenous fluids, giving sets, cannulae etc.cannulae etc.

Intravenous infusionIntravenous infusion: reconstituted freeze-dried or : reconstituted freeze-dried or neat liquid antivenom is diluted in approximately 5-neat liquid antivenom is diluted in approximately 5-10 ml of isotonic fluid per kg body weight (ie 250-10 ml of isotonic fluid per kg body weight (ie 250-500 ml of isotonic500 ml of isotonic

saline or 5% dextrose in the case of an adult saline or 5% dextrose in the case of an adult patient) and is infused at a constant rate over a patient) and is infused at a constant rate over a period of about one hourperiod of about one hour

Local administrationLocal administration of antivenom at the site of of antivenom at the site of the bite is not recommendedthe bite is not recommended

Extremely painfulExtremely painful Increase intracompartmental pressureIncrease intracompartmental pressure Not effective.Not effective.Intramuscular injectionIntramuscular injection of antivenom of antivenom Antivenoms are large molecules are absorbed Antivenoms are large molecules are absorbed

slowly via lymphatics.slowly via lymphatics. Bioavailability is poor, especially after intragluteal Bioavailability is poor, especially after intragluteal

injection and blood levels of antivenom never reach injection and blood levels of antivenom never reach those achieved rapidly by intravenous administration. those achieved rapidly by intravenous administration.

Pain of injection of large volumes of antivenom Pain of injection of large volumes of antivenom Risk of haematoma formation in patients with Risk of haematoma formation in patients with

haemostatic abnormalities.haemostatic abnormalities.

OTHER ROUTESOTHER ROUTES

CONTD…CONTD…

Situations in which intramuscular administration might be Situations in which intramuscular administration might be considered considered

1) At a peripheral first aid station, before a patient with 1) At a peripheral first aid station, before a patient with obvious envenoming is put in an ambulance for a journey to obvious envenoming is put in an ambulance for a journey to hospital that may last several hourshospital that may last several hours

2) On an expedition exploring a remote area very far from 2) On an expedition exploring a remote area very far from medical caremedical care

3) When intravenous access has proved impossible.3) When intravenous access has proved impossible. Although the risk of antivenom reactions is less with Although the risk of antivenom reactions is less with

intramuscular than intravenous administration, epinephrine intramuscular than intravenous administration, epinephrine (adrenaline) must be readily available.(adrenaline) must be readily available.

The dose of antivenom should be divided between a The dose of antivenom should be divided between a number of sites in the upper anterolateral region of both number of sites in the upper anterolateral region of both thighs.thighs.

A maximum of 5-10 ml should be given at each site by A maximum of 5-10 ml should be given at each site by deep intramuscular injection followed by massage to aid deep intramuscular injection followed by massage to aid absorption.absorption.

Finding enough muscle mass to contain such large Finding enough muscle mass to contain such large volumes of antivenom is particularly difficult in childrenvolumes of antivenom is particularly difficult in children

Dose of antivenomDose of antivenom

The recommended dose is often the amount of The recommended dose is often the amount of antivenom required to neutralise the average antivenom required to neutralise the average venom yield when captive snakes are milked of venom yield when captive snakes are milked of their venom. their venom.

In practice, the choice of an initial dose of In practice, the choice of an initial dose of antivenom is usually empirical.antivenom is usually empirical.

Since the neutralising power of antivenoms varies Since the neutralising power of antivenoms varies from batch to batch, the results of a particular from batch to batch, the results of a particular clinical trial may soon become obsolete if the clinical trial may soon become obsolete if the manufacturers change the strength of the manufacturers change the strength of the antivenom.antivenom.

Snakes inject the same dose of venom into Snakes inject the same dose of venom into children and adults.children and adults.

Children must therefore be given exactly Children must therefore be given exactly the same dose of antivenom as adults.the same dose of antivenom as adults.

How much ?How much ?

Intial dose to neutralise likely average dose Intial dose to neutralise likely average dose venom of the snakevenom of the snake

Russell viper – 63 mg +/-7mgRussell viper – 63 mg +/-7mg Indian ASV 1 vial neutralises 7mg of venom – so Indian ASV 1 vial neutralises 7mg of venom – so

10 vials ![starting dose ]10 vials ![starting dose ] COBRA -100-150 ml +neostigmine +ventilatory COBRA -100-150 ml +neostigmine +ventilatory

supportsupport VIPER -150 ml –retest 6 hrs-no clot –ASV 50-VIPER -150 ml –retest 6 hrs-no clot –ASV 50-

100ml- retest /observe100ml- retest /observe If in renal failure - dialysisIf in renal failure - dialysis

ADVERSE REACTIONS OF ASVADVERSE REACTIONS OF ASV NO test dose – [poor predictors & may sensitise NO test dose – [poor predictors & may sensitise

the patient to ASV]the patient to ASV] A proportion of patients, usually more than 20%, A proportion of patients, usually more than 20%,

develop a reaction either early (within a few develop a reaction either early (within a few hours) or late (5 days or more) after being given hours) or late (5 days or more) after being given antivenom.antivenom.

Early anaphylactic reactionsEarly anaphylactic reactions: usually within 10-: usually within 10-180 minutes of starting antivenom, the patient 180 minutes of starting antivenom, the patient begins to itch (often over the scalp) and develops begins to itch (often over the scalp) and develops urticaria, dry cough, fever, nausea,urticaria, dry cough, fever, nausea,

vomiting, abdominal colic, diarrhoea and vomiting, abdominal colic, diarrhoea and tachycardia.tachycardia.

A minority of these patients may develop severe A minority of these patients may develop severe life-threatening anaphylaxis: hypotension, life-threatening anaphylaxis: hypotension, bronchospasm and angio-oedema. bronchospasm and angio-oedema.

CONTD…CONTD… Pyrogenic (endotoxin) reactionsPyrogenic (endotoxin) reactions usually develop 1-2 hours usually develop 1-2 hours

after treatment. Symptoms include shaking chills (rigors), after treatment. Symptoms include shaking chills (rigors), fever, vasodilatation and a fall in blood pressure. Febrile fever, vasodilatation and a fall in blood pressure. Febrile convulsions may be precipitated in children. These convulsions may be precipitated in children. These reactions are caused by pyrogen contamination during the reactions are caused by pyrogen contamination during the manufacturing process. They are commonly reported.manufacturing process. They are commonly reported.

Late (serum sickness type) reactionsLate (serum sickness type) reactions develop 1-12 (mean 7) develop 1-12 (mean 7) days after treatment. Clinical features include fever, days after treatment. Clinical features include fever, nausea, vomiting, diarrhoea, itching, recurrent urticaria, nausea, vomiting, diarrhoea, itching, recurrent urticaria, arthralgia, myalgia, lymphadenopathy, periarticular arthralgia, myalgia, lymphadenopathy, periarticular swellings, mononeuritis multiplex, proteinuria withswellings, mononeuritis multiplex, proteinuria with

immune complex nephritis and rarely encephalopathy. immune complex nephritis and rarely encephalopathy.

Patients who suffer early reactions and are treated with Patients who suffer early reactions and are treated with antihistamines and corticosteroid are less likely to develop antihistamines and corticosteroid are less likely to develop late reactions.late reactions.

Treatment of early Anaphylactic and Treatment of early Anaphylactic and Pyrogenic Antivenom reactionsPyrogenic Antivenom reactions

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 Epinephrine (adrenaline) (0.1% solution, 1 in 1,000, Epinephrine (adrenaline) (0.1% solution, 1 in 1,000,

1 mg/ml) is the effective treatment for early 1 mg/ml) is the effective treatment for early anaphylactic and pyrogenic antivenom reactionsanaphylactic and pyrogenic antivenom reactions

Epinephrine (adrenaline) is given intramuscularly (into the Epinephrine (adrenaline) is given intramuscularly (into the deltoid muscle or the upper lateral thigh) in an initial dose deltoid muscle or the upper lateral thigh) in an initial dose of 0.5 mg for adults, 0.01 mg/kg body weight for children. of 0.5 mg for adults, 0.01 mg/kg body weight for children.

Severe,life-threatening anaphylaxis can evolve very rapidly Severe,life-threatening anaphylaxis can evolve very rapidly and so epinephrine (adrenaline) should be given at the very and so epinephrine (adrenaline) should be given at the very first sign of a reaction, even when only a few spots of first sign of a reaction, even when only a few spots of urticaria have appeared or at the start of itching, urticaria have appeared or at the start of itching, tachycardia or restlessness. tachycardia or restlessness.

The dose can be repeated every 5-10 minutes if the The dose can be repeated every 5-10 minutes if the patient’s condition is deteriorating patient’s condition is deteriorating

Anti H1 antihistamine such as chlorpheniramine maleate Anti H1 antihistamine such as chlorpheniramine maleate (adults 10 mg, children 0.2 mg/kg by intravenous injection (adults 10 mg, children 0.2 mg/kg by intravenous injection over a few minutes) over a few minutes)

Intravenous hydrocortisone (adults 100 mg, children 2 Intravenous hydrocortisone (adults 100 mg, children 2 mg/kg bodyweight) - prevent recurrent anaphylaxis.mg/kg bodyweight) - prevent recurrent anaphylaxis.

Anti H2 antihistamines such as cimetidine or ranitidine have Anti H2 antihistamines such as cimetidine or ranitidine have a role in the treatment of severe anaphylaxis. a role in the treatment of severe anaphylaxis.

Both drugs are given, diluted in 20 ml isotonic saline, by Both drugs are given, diluted in 20 ml isotonic saline, by slow intravenous injection (over 2 minutes). Doses: slow intravenous injection (over 2 minutes). Doses: cimetidine - adults 200 mg, children 4 mg/kg;ranitidine - cimetidine - adults 200 mg, children 4 mg/kg;ranitidine - adults 50 mg, children 1 mg/kg.adults 50 mg, children 1 mg/kg.

Late (serum sickness) reactionsLate (serum sickness) reactions usually respond to a 5-day usually respond to a 5-day course of oral antihistamine. Patients who fail to respond in course of oral antihistamine. Patients who fail to respond in 24-48 hours should be given a 5-day course of 24-48 hours should be given a 5-day course of prednisolone.prednisolone.

Doses: Chlorpheniramine: adults 2 mg six hourly, children Doses: Chlorpheniramine: adults 2 mg six hourly, children 0.25 mg/kg /day in divided doses0.25 mg/kg /day in divided doses

Prednisolone: adults 5 mg six hourly, children 0.7 Prednisolone: adults 5 mg six hourly, children 0.7 mg/kg/day in divided doses for 5-7daysmg/kg/day in divided doses for 5-7days

Recurrence of systemic envenomingRecurrence of systemic envenoming

In patients envenomed by vipers, after an initial In patients envenomed by vipers, after an initial response to antivenom (cessation of bleeding, response to antivenom (cessation of bleeding, restoration of blood coagulability), signs of restoration of blood coagulability), signs of systemic envenoming may recur within 24-48 systemic envenoming may recur within 24-48 hours.hours.

This is attributable to:This is attributable to: Continuing absorption of venom from the Continuing absorption of venom from the

“depot” at the site of the bite, perhaps assisted “depot” at the site of the bite, perhaps assisted by improved blood supply following correction of by improved blood supply following correction of shock, hypovolaemia etc.shock, hypovolaemia etc.

A redistribution of venom from the tissues A redistribution of venom from the tissues into the vascular space, as the result of into the vascular space, as the result of antivenom treatment.antivenom treatment.

Conservative treatment when no Conservative treatment when no antivenom is availableantivenom is available

Neurotoxic envenoming with respiratory paralysisNeurotoxic envenoming with respiratory paralysis: assisted : assisted ventilation. Anticholinesterases should always be triedventilation. Anticholinesterases should always be tried

Haemostatic abnormalitiesHaemostatic abnormalities - strict bed rest to avoid even minor - strict bed rest to avoid even minor traumatrauma

transfusion of clotting factors and platelets; transfusion of clotting factors and platelets; fresh frozen plasma and cryoprecipitate with plateletfresh frozen plasma and cryoprecipitate with platelet concentratesconcentrates fresh whole blood.fresh whole blood. Intramuscular injections should be avoided.Intramuscular injections should be avoided. Shock, myocardial damageShock, myocardial damage: : Hypovolaemia corrected withHypovolaemia corrected with colloid/crystalloid, colloid/crystalloid, Ancillary pressor drugs (dopamine or adrenaline)Ancillary pressor drugs (dopamine or adrenaline) Renal failureRenal failure: conservative treatment or dialysis : conservative treatment or dialysis Dark brown urineDark brown urine (myoglobinuria or haemoglobinuria) (myoglobinuria or haemoglobinuria) correct correct

hypovolaemia and acidosis and consider a single infusion of mannitol hypovolaemia and acidosis and consider a single infusion of mannitol Severe local envenomingSevere local envenoming Surgical intervention may be needed but the risks of surgery in a Surgical intervention may be needed but the risks of surgery in a

patient with consumption coagulopathy, thrombocytopenia and patient with consumption coagulopathy, thrombocytopenia and enhanced fibrinolysis must be balanced against the life threatening enhanced fibrinolysis must be balanced against the life threatening complications of local envenoming.complications of local envenoming.

Prophylactic broad spectrum antimicrobial treatment is justifiedProphylactic broad spectrum antimicrobial treatment is justified

Anticholinesterase (eg “Tensilon”/edrophonium) Anticholinesterase (eg “Tensilon”/edrophonium) testtest

Baseline observationsBaseline observations Give atropine intravenouslyGive atropine intravenously Give anticholinesterase drugGive anticholinesterase drug Observe effectObserve effect If positive, institute regular atropine and (long If positive, institute regular atropine and (long

acting) anticholinesteraseacting) anticholinesterase

Criteria for giving more antivenomCriteria for giving more antivenom Persistence or recurrence of blood Persistence or recurrence of blood

incoagulability after 6 hr of bleeding after incoagulability after 6 hr of bleeding after 1-2 hr1-2 hr

Deteriorating neurotoxic or cardiovascular Deteriorating neurotoxic or cardiovascular signs after 1-2 hrsigns after 1-2 hr

If the blood remains incoagulable If the blood remains incoagulable (as (as measured by 20WBCT) six hours after the initial measured by 20WBCT) six hours after the initial dose of antivenom, the same dose should be dose of antivenom, the same dose should be repeated.repeated.

In patients who continue to bleed brisklyIn patients who continue to bleed briskly, , the dose of antivenom should be repeated within the dose of antivenom should be repeated within 1-2 hours.1-2 hours.

In case of deteriorating neurotoxicity or In case of deteriorating neurotoxicity or cardiovascular signscardiovascular signs, the initial dose of , the initial dose of antivenom should be repeated after 1-2 hours, antivenom should be repeated after 1-2 hours, and full supportive treatment must be and full supportive treatment must be considered.considered.

How can snake bites be avoidedHow can snake bites be avoided??

Education ! Know your local snakes, Education ! Know your local snakes, know the sort of places where they like to know the sort of places where they like to live and hide, know at what times of year, live and hide, know at what times of year, at what times of day/night or in what kinds at what times of day/night or in what kinds of weather they are most likely to be of weather they are most likely to be active.active.

Be vigilant after rains, during flooding, at Be vigilant after rains, during flooding, at harvest time and at night.harvest time and at night.

Wear proper shoes or boots and long Wear proper shoes or boots and long trousers, especially when walking in the trousers, especially when walking in the dark or in undergrowth.dark or in undergrowth.

Use a light (torch) when walking at night.Use a light (torch) when walking at night.

CONTD…CONTD… Avoid snakes as far as possible, including Avoid snakes as far as possible, including

snakes performing for snake charmers. snakes performing for snake charmers. Never handle, threaten or attack a snake Never handle, threaten or attack a snake and never intentionally trap or corner a and never intentionally trap or corner a snake in an enclosed space.snake in an enclosed space.

Avoid sleeping on the ground.Avoid sleeping on the ground. Keep young children away from areas Keep young children away from areas

known to be snake-infested.known to be snake-infested. Avoid or take great care handling dead Avoid or take great care handling dead

snakes, or snakes that appear to be snakes, or snakes that appear to be dead.dead.

Avoid having rubble, rubbish, termite Avoid having rubble, rubbish, termite mounds or domestic animals close to mounds or domestic animals close to human dwellings, as all of these attract human dwellings, as all of these attract snakes.snakes.

CONTD…CONTD…

Frequently check houses for snakes and, avoid types Frequently check houses for snakes and, avoid types of house construction that will provide snakes with of house construction that will provide snakes with hiding places (eg thatched roof with open eaves, mud hiding places (eg thatched roof with open eaves, mud and straw walls with large cracks and cavities, large and straw walls with large cracks and cavities, large unsealed spaces beneath floorboards).unsealed spaces beneath floorboards).

To prevent sea snake bites, fishermen should avoid To prevent sea snake bites, fishermen should avoid touching sea snakes caught in nets and on lines. The touching sea snakes caught in nets and on lines. The head and tail are not easily distinguishable. There is a head and tail are not easily distinguishable. There is a risk of bites to bathers and those washing clothes in risk of bites to bathers and those washing clothes in muddy water of estuaries, river mouths and some muddy water of estuaries, river mouths and some coastlinescoastlines

CASE REPORT Year CASE REPORT Year : 2007  |  : 2007  |  VolumeVolume : 11  |  : 11  |  IssueIssue : 3  |  : 3  |  PagePage : 161-164 Neurotoxic snake bite with respiratory : 161-164 Neurotoxic snake bite with respiratory

failurefailure  Department of Anesthesiology, Institute of Medical Sciences, Banaras Hindu University, Department of Anesthesiology, Institute of Medical Sciences, Banaras Hindu University,

Varanasi - 221 005, IndiaVaranasi - 221 005, India Thirteen patients with severe neuroparalytic snake envenomation Thirteen patients with severe neuroparalytic snake envenomation

admitted in intensive care unit with respiratory failure over a four admitted in intensive care unit with respiratory failure over a four months period. Initially ptosis and ophthalmoplegia, followed by months period. Initially ptosis and ophthalmoplegia, followed by bulbar palsy and respiratory muscle weakness was the common bulbar palsy and respiratory muscle weakness was the common sequele.sequele.

All of them received cardio-respiratory support with mechanical All of them received cardio-respiratory support with mechanical ventilation, anti-snake venom (median dose of 20 vials) and ventilation, anti-snake venom (median dose of 20 vials) and anticholinesterase therapy.anticholinesterase therapy.

Except one suffering from hypoxic brain injury due to delayed Except one suffering from hypoxic brain injury due to delayed presentation, rest survived with complete neurological recovery.presentation, rest survived with complete neurological recovery.

So good outcome in such cases is related with early cardio respiratory So good outcome in such cases is related with early cardio respiratory support and anti venom therapysupport and anti venom therapy

Polyvalent anti-snake venom (ASV) started as loading dose (50 ml Polyvalent anti-snake venom (ASV) started as loading dose (50 ml over two hours) and maintenance infusion (50 ml six hourly). over two hours) and maintenance infusion (50 ml six hourly).

We have also used anticholinesterase (i.e. neostigmine started at a We have also used anticholinesterase (i.e. neostigmine started at a rate of 25 mcg/kg/hour) and anticholinergic (glycopyrolate) rate of 25 mcg/kg/hour) and anticholinergic (glycopyrolate) combination as infusion to reverse the neuromuscular blockade till combination as infusion to reverse the neuromuscular blockade till ptosis improved in every case ptosis improved in every case

Low dose of snake antivenom is as effective as high dose in Low dose of snake antivenom is as effective as high dose in patients with severe neurotoxic snake envenoming patients with severe neurotoxic snake envenoming

Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and ResearchDepartment of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research, ,

Chandigarh, IndiaChandigarh, India In the study, 55 snake bite victims requiring ventilatory support for In the study, 55 snake bite victims requiring ventilatory support for

severe neurotoxic envenoming received either 150 ml of polyvalent severe neurotoxic envenoming received either 150 ml of polyvalent snake antivenom (SAV) (low dose SAV group, n = 28) or 100 ml of SAV snake antivenom (SAV) (low dose SAV group, n = 28) or 100 ml of SAV at presentation followed by 100 ml every 6 hours until recovery of at presentation followed by 100 ml every 6 hours until recovery of neurological manifestations (high dose group, n = 27). neurological manifestations (high dose group, n = 27).

The median dose of SAV in the high dose group was 600 ml (range 300 The median dose of SAV in the high dose group was 600 ml (range 300 to 1600). to 1600).

The duration of mechanical ventilation in the low dose group (median The duration of mechanical ventilation in the low dose group (median 47.5 hours; range 14 to 248) was similar to that in the high dose group 47.5 hours; range 14 to 248) was similar to that in the high dose group (median 44 hours; range 6 to 400). (median 44 hours; range 6 to 400).

The mean (SD) duration of intensive care unit stay was similar in the The mean (SD) duration of intensive care unit stay was similar in the two groups.two groups.

There were three deaths in the high dose group; two patients in the There were three deaths in the high dose group; two patients in the low dose group had neurological sequelae. All other patients improved, low dose group had neurological sequelae. All other patients improved, had no residual neurological deficit, and were discharged.had no residual neurological deficit, and were discharged.

We conclude that there is no difference between a protocol using We conclude that there is no difference between a protocol using lower doses of SAV and one with higher doses in the management of lower doses of SAV and one with higher doses in the management of patients with severe neurotoxic snake envenomingpatients with severe neurotoxic snake envenoming

REFERENCESREFERENCES WHO/SEARO GUIDELINES FOR THE CLINICAL WHO/SEARO GUIDELINES FOR THE CLINICAL

MANAGEMENT OF SNAKE BITE IN THE SOUTH MANAGEMENT OF SNAKE BITE IN THE SOUTH EAST ASIAN REGION EAST ASIAN REGION by David A Warrell-by David A Warrell-Supplement to The Southeast Asian Journal Supplement to The Southeast Asian Journal of Tropical Medicine & Public Healthof Tropical Medicine & Public Health