snake bite management
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SNAKE BITE
Dr.A. Sridhar Ist year pg
Snake bite• 3000 species of snakes, out of them only 10-15%
of snakes are venomous• 300 species are in India• .INDIAN snakes ranges from
Wormsnakes—10cm to
KING COBRA—6M.
.70% bites are from non-venomous species,5O%bites by venomous species doesn’t cause envenomation.{dry bites}
.
Important species in INDIA
• Cobras(nagraj) –Naja naja,N.oxiana,
N.kabuthia
• Common krait(karayat)-Bungarus
caeruleus
• Russell’s viper(kander)-Daboia russelii
• Saw scaled viper - Echis.carinatus(afai)
COBRA
COMMON KRAIT
RUSSEL’S VIPER
ECHIS CARINATUS
Approximately 2500 different species of snakes are known. Approximately
Poisonous Snakes Head – Triangle Fangs – Present Pupils - Elliptical pupil Anal Plate - Single row Bite Mark - Fang Mark Non Poisonous Snakes Head - Rounded
Fangs - Not presentPupils - RoundedAnal Plate - Double row Bite Mark - Row of small teeth.
• How to identify a dead snake if it is brought to the ER
• Carefully handle the snake because even dead snake fangs can transmit poison
• Viper fangs are anterior,lengthy & loose• Elapidae have short,thick anterior fangs
SNAKE VENOM
• Snakes that inject venom use glands, which are actually modified salivary glands.
• Venom is a modified form of saliva and probably evolved to aid in chemical digestion.
• Varying degrees of toxicity also make it useful in killing prey.
VENOM APPARATUS
• The venom glands of elapidae & viperidae are situated behind the eyes & surrounded by compressor muscles
• Venom duct opens withinin the sheath at the base of the fang
• Venom is conducted to fang tip through a canal
Venom properties
• Contain 20 or more components• >90% of the dry Wt of venom is protein- in
the form of enzymes,non enzymatic polypeptide toxins & non toxic proteins .
• Most venoms contain L-aminoacid oxidase, phosphomono & diesterases, 5-nucleotidase,DNAase,NAD-nucleosidase, phospholipaseA2 & peptidases
Contd
• Phospholipase A2(lecithinase) damages
mitochondria,RBCs,WBCs,platelets, peripheral
nerve endings,skeletal muscles, vascular
endothelium & other membranes, produces
presynaptic neurotoxic activity & release of
histamine
Contd
• Proteolytic enzymes(endopeptidases &
hydrolases) are responsible for local changes
in vascular permeability leading to
edema,blistering & bruising & to necrosis
• Hyaluronidase promotes the spread of venom
through tissues
POLYPEPTIDE TOXINS• Postsynaptic () neurotoxins such as -
bungarotoxin and cobrotoxin,are bind to acetylcholine receptors at the motor endplate
• Presynaptic(β)neurotoxins such as β- bungarotoxin,crotoxin,& taipoxin release acetylcholine at the nerve endings at NMJs & then damage the endings,preventing furthur release of the transmitter
PHARMACOLOGY
• Absorbed through the blood & lymphatics• Spitting cobra- venom can be absorbed
through the intact cornea• Most venoms are concentrated in the
kidneys & some are eliminated in urine• Bungarotoxin are tightly bound at the NMJ• Most venoms donot cross the blood brain
barrier
Clinical features
• When venom not injected :• Anxious people-hyperventilation-stiffness,
tetany of hands and feet, dizzines• Vasovagal shock-few• First aid measures-constriction bands-pain,
swelling, congestion
When venom injected
• Nausea & vomiting are common early symptoms
of systemic envenoming
• Early syncope,vomiting,colic,diarrhoea,
angioedema & wheezing may occur
• Local pain & bleeding from the fang
punctures,swelling, bruising ,lymphangitis &
regional lymphadenopathy
Bites by cobra
• More of neurotoxic ,local effects• Neurotoxic-• Ptosis• Ciliary mussle paralysis• Partial/total opthalmoplegia• Broken neck sign• Bulbar palsy• Locked-in syndrome
Bites by kraits
• Most poisonous snake in india• Local urticaria-rare• Delayed neuropathy of affected limb-rare• Bulbar palsy• Respiratory paralysis• Asphyxic cardiac arrest• No local pain or tissue damage
Bites by Viper
• cytotoxic & hemotoxic
• Severe local effects• Rapid devlopment of DIC• Immediate shock• Neuroparalysis-ptosis,respiratory paralysis• Sheehans syndrome
• Pain & tenderness in regional lymph nodes with bruising of overlying tissues & lymphangitic lines
• Bruising ,blistering & necrosis may appear in the next few days
• Compartment syn may develop
Contd
• Haemostatic abnormalities are characteristic of envenoming by viperidae
• Hypotension & shock are common• Myocardial involvement may be present• Early collapse after bites has been attributed
to coronary & pulmonary thromboembolism
Contd
• Oliguria & loin pain indicate renal ischaemia
• Generalised rhabdomyolysis
• myoglobinuria
• Renal failure is a common mode of death
• Sawscaled viper doesn’t causeneurological or
renal complications
ecchymosis
•
Necrosis Bite marks
•
Bites by Sea snake
• Both myotoxic&haematotoxic
• Trismus is common
• Between 30mins to 3.5hrs,generalized
aching,stiffness & tenderness of the muscles.
• Later there is generalized flaccid paralysis
Contd
• Myoglobinuria appears 3 to 8hrs after the bite
• Myoglobin & potassium released from
damaged skeletal muscle can cause renal
failure
Investigations
• CBC • RFT • Coagulation studies • Blood grouping & cross matching• Sr.electrolytes• Urinalysis
Contd
• 20 min whole blood clotting test• Sr.creatine kinase,myoglobin & potassium
levels• ECG-sinus bradycardia,ST-T changes,
various degrees of AV block & hyperkalaemic changes
• Immunodiagnosis
MANAGMENT• “Do it R.I.G.H.T.” • It consists of the following: • R. = Reassure the patient. • I = Immobilise in the same way as a fractured
limb. Use bandages or cloth to hold the splints, Do not apply ligatures
• G. H. = Get to Hospital Immediately.. • T= Tell the doctor of any systemic symptoms
such as ptosis that manifest on the way to hospital.
Antivenom ,antivenin,antivenene & antisnake serum
• POLYVALENT ANTIVENINS
• MONOVALENT ANTIVENINS: Highly effective
against a particular species & are available
only in some countries based on the
epidemicity of specific snakes
POLYVALENT ANTIVENIN
• Manufactured by hyper immunizing horses against venoms of four standard snakes
• Cobra (naja naja)• Krait (B.caerulus)• Russel’s viper(V.russelli)• Saw scaled viper(Echis carinatus)
• Lyophilised form:stored in a cool dark place & may last for 5 years
• Liquid form:has to be stored at 4°c with much shorter life span,2Yrs
• Each 1ml of reconstituted serum neutralise
• 0.6 mg of naja naja• 0.45 mg of Bungarus caerulus• 0.6 mg of V.russelli• 0.45 mg of Echis carinatus
Approximate initial dose
• Common krait-100ml
• Russell’viper- 100ml
• Indian cobra-100ml
• Echis spp-100ml
• Given at the rate of 2ml/min IV push or as iv
infusion with 5ml/kg of isotonic fluid ,all ASV has2be administered in 1hr
• ROUTE OF ADMINISTRATION--IV
• WHY NOT IM?
• WHEN TO GIVE IM?
Indications for antivenom
• Local envenoming• Local swelling involving more than half of the
bitten limb (in the absence of a tourniquet) Swelling after bites on the digits (toes and especially fingers)
Indications for antivenom
• Local envenoming• Rapid extension of swelling (for example
beyond the wrist or ankle within a few hours of bites on the hands or feet)
• Development of an enlarged tender lymph node draining the bitten limb
Indications for antivenom
• Systemic envenoming• • Haemostatic abnormalities: spontaneous
systemic bleeding (clinical), coagulopathy (20WBCT or other laboratory) or thrombocytopenia (<100 x109/litre) (laboratory)
Indications for antivenom
• • Neurotoxic signs: ptosis, external ophthalmoplegia, paralysis etc (clinical)
• • Cardiovascular abnormalities: hypotension, shock, cardiac arrhythmia (clinical), abnormal ECG
Indications for antivenom
• • Acute renal failure: oliguria/anuria (clinical), rising blood creatinine/ urea
• • (Haemoglobin-/myoglobin-uria:) dark brown urine (clinical), urine dipsticks, other evidence of intravascular haemolysis or generalised rhabdomyolysis (muscle aches and pains, hyperkalaemia)
Treatment of antivenom reactions
• Early (anaphylactic) reactions,occur within 10-180
min
Adrenaline 0.5 mg ,1:1000,IM
. If hypotension,severe bronchospasm or laryngeal
edema give 0.5 mg,1:10000of adrenaline IV
Contd
• A histamine anti H1 blocker-chlorphenira- mine
maleate-10 mg IV
• Pyrogenic reactions-occurs 1-2hrs after treatment, give
antipyretics
• Late reactions-occur 1-12daysafter treatment respond
to CPM-2 mg, 6 hrly or oral prednisolone-5 mg 6 hrly
Contd
• If patient goes for airway obstruction &
respiratory paralysis
MECHANICALVENTILATION
Supportive treatment
• First do NEOSTIGMINE TEST• IF VICTIM RESPONDS CONTINUE WITH 0.5 mg
of neostigmine IM ,half hourly plus 0.6mg of atropine IV over an 8hr period by continuous infusion
• If there is no improvement after 1hr neostigmine should be stopped
Contd
• Hypotension & shock-a plasma expander, dopamine.
• Oliguria & renal failure-fluids,diuretics, dopamine-if no response,fluid restriction, dialysis
• Local infection-TT,antibiotics
Contd
• Intracompartmental syn & fasciotomy
• Haemostatic disturbances-FFP,fresh whole blood,cryoprecipitates
• Treatment of snake venom ophthalmia- topical antimicrobial,0.1% adrenaline relieves pain
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