A&E(VMH)
Dr Pavan .M
MD(A &EM), VMKVMC
A&E(VMH)
Epidemiology
• 3 million bites and 1,50,000 deaths/year from venomous snake worldwide.
• Bites highest in temperate and tropical regions.• 3000 species of snakes, out of them only 10-15% of
snakes are venomous• 97% of all snake bites are on the extremities
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Common Snakes - INDIA
• Cobras(nagraj) –Naja naja,N.oxiana, N.kabuthia
• Neurotoxicity usually
predominates.
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• Common krait(karayat)-Bungarus caeruleus
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• Russell’s viper(kander)-Daboia russelii• Heat-sensing facial pits
(hence the name "pit vipers").
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• Echis.carinatus(afai)-Saw scaled viper
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Approximately 2500 different species of snakes are known. Approximately
Non Poisonous Snakes Head - Rounded
Fangs - Not presentPupils - RoundedAnal Plate - Double row Bite Mark - Row of small teeth.
Poisonous Snakes Head – Triangle Fangs – Present Pupils - Elliptical pupil Anal Plate - Single row Bite Mark - Fang Mark
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Snake Venom
• Snake venom is highly modified saliva
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Mechanism of toxicity• Cytotoxic effects on tissues• Hemotoxic• Neurotoxic• Systemic effects.
• Toxic dose. The potency of the venom and the amount of venom injected vary considerably.
• 20% of all strikes are "dry"
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Snake Venom, Necrosis
• Proteolytic enzymes have a trypsin-like activity.
• Hyaluronidase splits acidic mucopolysaccharides and promotes the distribution of venom in the extracellular matrix of connective tissue.
• Phospholipases A2- break down membrane phospholipids -causes cellular membrane damage
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Contd..• All these enzymes cause oedema, blister
formation and local tissue necrosis
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Snake Venom ,Paralysis
• Blocks the stimulus transmission from nerve cell to muscle and cause paralysis
• Does not penetrate the blood-brain barrier
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•
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Contd..
• Postsynaptic effects are reversible with antivenom and neostigmine.
• Presynaptic nerve terminal, e.g. beta-bungarotoxin and here neostigmine will not be effective.
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Snake venom, Hemorrhages• Activate prothrombin (e.g. ecarin from Echis carinatus)
• Effect on fibrinogen and convert it into fibrin -thrombin-like activity, such as crotalase (rattlesnake venom)
• Activate factor 5, factor 10 , Protein C
• Activate or inhibit platelet aggregation
• Haemmorhagins- cause endothelial damage
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•
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Clinical syndromic approachSyndrome 1
• Local envenoming
(swelling etc) with
bleeding/clotting
disturbances
VIPERIDAE
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Syndrome 2
Ptosis, external opthalmoplegia, facial paralysis etc and dark brown urine=Russell's viper, Sri Lanka and South India
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Syndrome 3
Local envenoming (swelling etc) with paralysis=Cobra or king cobra
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Syndrome 4
• Paralysis with minimal or no local envenoming
Krait, Sea snake
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Syndrome 5
• Paralysis with dark brown urine and renal failure: Russle viper
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Grade 0
• No evidence of envenomation• Suspected snake bite• Fang mark may be present• Pain and 1 inch edema & erythema• No systemic signs- first 12 hours• No lab changes
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Grade 1
• Minimal envenomation• Fang wound & moderate pain present• 1-5 inches of edema or erythema• No systemic involvement in present after 12 hours• No lab changes
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Grade 2
Moderate envenomation
Severe pain
Edema spreading towards trunk
Petechiae and ecchymosis limited area
Nausea,vomiting,giddiness
Mild temperature
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Grade 3
• Severe envenomation• Within 12 hours edema spreads to the extremities
and part of trunk.• Petechiae and ecchymosis may be generalized• Tachycardia• Hypotension• Subnormal temperature
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Grade 4
• Envenomation very severe• Sudden pain rapidly• Progressive swelling which leads to ecchymosis all
over trunk • Bleb formation and necrosis
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Grade 4 contd…• Systemic manifestations within 15 min after the bite• Weak pulse,N&V,vertigo• Convulsions, coma
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What investigation to do?
• CBC • RFT • Coagulation studies • Blood grouping & cross matching• Sr.electrolytes• Urinalysis
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20 min whole blood clotting time
• A few milliliters of fresh blood are placed in a new, plain glass receptacle (e.g., test tube) and left undisturbed for 20 min.
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Contd…• The tube is then tipped once to 45° to determine
whether a clot has formed. If not, coagulopathy is diagnosed
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Hess's test
• Blow up a blood pressure cuff to 80 mm Hg and leave it on for 5 minutes.
• If a crop of purpuric spots appears below the cuff, the test is positive.
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First AidFirst Aid
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Donts
• No Tornique• No Suction apparatus to be used(Sawyers)• Do not run • No role of Ice application
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ASV• When to use ASV?• How much to use?• What if a reaction occurs?• When to stop ASV?
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When to use ASV•Hemostatic abnormalities(lab and clinical)
•Progressive local findings
•Neurotoxicity
•Systemic signs and symptoms
•Generalised rhabdomyolysis
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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)
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Contd..• 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
• Each 1ml of reconstituted serum neutralise0.6 mg of naja naja0.45 mg of Bungarus caerulus0.6 mg of V.russelli0.45 mg of Echis carinatus
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Guide for initial dose of antivenin
Grade Amount of
Antivenin
Route
0 None None
1 None None
2 5 vials IV 1:10 dilutions
3 5-10 vials IV 1:10 dilutions
4 10-20 vials IV 1:10 dilutions
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Dose in Paediatric
• Same as adult as the amount of venom does not change-hence the dose of antivenom should be the same
• Only the dilution changes
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Skin testing- Done if patient is stable and time available
• 0.02ml of 1:100 solution of serum is injected sc
• A positive reaction occurs within 5 to 30 mins.
• Appearance of wheal & surrounding erythema
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What to do in case of anaphylactic reaction to ASV
• Adrenaline 0.5 to 1ml IM
• If hypotension,severe bronchospasm or laryngeal edema give 0.5 ml of adrenaline diluted in 20 ml of isotonic saline over 20 mins iv.
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contd..• A histamine anti H1 blocker-chlorpheniramine maleate-10
mg IV
• Pyrogenic reactions-antipyretics
• Late reactions-respond to CPM-2 mg, 6 hrly or oral prednisolone-5 mg 6 hrly
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What if the patient needs ASV following reaction
• Dose should be further diluted in isotonic saline and restarted as soon as possible.
• Concomitant IV infusion of epinephrine may be required to hold allergic sequelae at bay while further antivenom is administered
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When to stop using ASV
• Bleeding subsides• Lab values returns to baseline• Signs of neurotoxicity reverses• Local effects halts progression
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Supportive treatment
• Anticholineesterase have variable but useful role
Trial• Atropine sulphate 0.6 mg• Edrophonium chloride 10 mg IV (or) Neostigmine:
1.5–2.0 mg IM (children, 0.025–0.08 mg/kg)
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Contd..
If objective improvement is evident at 5 min • continue neostigmine at a dose of 0.5 mg (children,
0.01 mg/kg) every 30 min as needed with• atropine by continuous infusion of 0.6 mg over 8 h -
children, 0.02 mg/kg over 8 h
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Contd
Hypotension
• Administration of crystalloid (20–40 mL/kg)
• Trial of 5% albumin (10– 20mL/kg)
• CVP guided fluids
• Inotropic support and invasive monitoring
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Contd..
• Oliguria & renal failure- fluids,diuretics, dopamine
no response-fluid restriction- Dialysis
• Local infection- TT,antibiotics
• Haemostatic disturbances-FFP,fresh whole
blood,cryoprecipitates
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Cobra spit opthalmia• Topical antimicrobial• 0.1% adrenaline relieves pain• No need for ASV
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Compartment syndrome
If signs of compartment syndrome are present and compartment pressure > 30 mm Hg:
• Elevate limb• Administer Mannitol 1-2 g/kg IV over 30 min• Simultaneously administer additional antivenom, 4-6
vials IV over 60 min
If elevated compartment pressure persists another 60
min, consider fasciotomy
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Bee Sting
Honey bee belong • Family- Hymenoptera • Sub Family-Apidae• Only the females have adapted a stinger from the
ovipositor on the posterior aspect of the abdomen
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Venom
• Histamine.
• Melittina –membrane active polypeptide that can cause degranulation of basophils and mast cells, constitutes more than 50 percent of the dry weight of bee venom
• Venom commonly causes pain, slight erythema, edema, and pruritus at the sting site
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Presentations
• Local reaction• Toxic manifestation and anaphylaxis• Delayed reaction –Serum sickness
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Treatment
• Immediate removal is the important principle and the method of removal is irrelevant.
• Sting site should be washed thoroughly with soap and water to minimize the possibility of infection.
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Contd..
• Intermittent ice packs at the site- diminish swelling and delay the absorption of venom while limiting edema.
• Oral antihistamines and analgesics may limit discomfort and pruritus.
• Nonsteroidal anti-inflammatory drugs (NSAIDs) can be effective in relieving pain
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Severe systemic reaction• Epinephrine 0.3 to 0.5 mg (0.3 to 0.5 mL of 1:1000
concentration) in adults and 0.01 mg/kg in children (never more than 0.3 mg).
• Injected IM and the injection site massaged to hasten absorption
• If hypotension,severe bronchospasm or laryngeal edema give 0.5 ml of adrenaline diluted in 20 ml of isotonic saline over 20 mins
• Observation for 24 hours in ICU
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Contd…• Parenteral antihistamines (diphenhydramine 25 to 50
mg IV, IM, or PO) and H2-receptor antagonists (ranitidine 50 mg IV)
• Steroids (methylprednisolone 125 mg) -to limit ongoing urticaria and edema and may potentiate the effects of other measures.
• Bronchospasm is treated with -agonist nebulization.
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Contd..
• Hypotension
-massive crystalloid infusion, and central venous pressure monitoring may be helpful in these patients.
-Persistent hypotension require dopamine.
-If dopamine is ineffective, an intravenous infusion of epinephrine can be used
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Preventive Care
• Every patient who has had a systemic reaction -insect sting kit containing premeasured epinephrine and be carefully instructed in its use.
• Patient must inject the epinephrine at the first sign of a systemic reaction.
• Medic alert tag
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Scorpion sting- C. exilicauda
• Scorpions have a world-wide distribution.
• Highly toxic species are found in the Middle East, India, North Africa, South America, Mexico, and the Caribbean island of Trinidad.
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Mechanism of action
• Venom can open neuronal sodium channels and cause prolonged and excessive depolarization
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Symptoms and sign• Somatic and autonomic nerves may be affected
• Initial pain and paresthesia at the stung extremity that becomes generalised
• Cranial nerve- abnormal roving eye movements, blurred vision, pharyngeal muscle incoordination and drooling and respiratory compromise
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Contd…• Excessive motor activity
• Nausea, vomiting, tachycardia, and severe agitation can also be present.
• Cardiac dysfunction, pulmonary edema, pancreatitis, bleeding disorders, skin necrosis, and occasionally death can occur
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Treatment• Pain Management• Ice pack• Immobilization of limb• Local anaesthetics are better than opiates
• Tetanus prophylaxis, wound care and antibiotics
• Benzodizepines for motor activity.
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Contd..• Stabilize Airway Breathing and Circulation
• Hyperdynamic circulation
Always combination of alpha blocker with beta blocker to prevent unopposed alpha action causing tachycardia
• Nitrates for Hypertension/MI
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Contd..• Hypodynamic Circulation:
CVP guided fluids
Decrease preload with furosemide (not hypovolumic)
Reduction of afterload improves outcome-Prazosin, nitroprusside, hydralizine, ACE inhibitor
• Dobutamine is the best inotrope, avoid Dopamine
• Noradrenaline can be used
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Newer modality• Insulin has shown to improve cardiopulmonary status
in case of scorpion envenomation
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