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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