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Snakebite Management: The Four Major Venomous Snakes of India

1. Indian Cobra (Naja naja) - Elapidae
2. Common Krait (Bungarus caeruleus) - Elapidae
3. Russell's Viper (Daboia russelli) - Viperidae
4. Saw-Scaled Viper (Echis carinatus) - Viperidae

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PART 1: IDENTIFICATION OF EACH SNAKE

1. Indian Cobra (Naja naja)

• Hood: Spreads a distinctive hood when threatened - most identifying feature
• Hood markings: Classic spectacle pattern (binocular mark) on dorsal hood; monocle pattern in some regional variants
• Length: 1.2-1.8 m
• Color: Brown, black, or yellowish; belly creamy white
• Fixed erect fangs (elapid type - short, front-fanged)
• Head: Slightly distinct from neck, rounded snout
• Pupils: Round

2. Common Krait (Bungarus caeruleus)

• Color: Shiny blue-black or black with narrow white/yellow cross bands (more prominent on posterior half)
• Length: 0.9-1.5 m
• Cross-section: Distinctly triangular/hexagonal body (vertebral ridge visible)
• Head: Small, barely distinct from neck; depressed
• Tail: Short, bluntly rounded
• Habits: Nocturnal; often found near human habitation; bites during sleep
• Fixed front fangs (elapid); small size makes bite marks barely visible

3. Russell's Viper (Daboia russelli)

• Pattern: Distinctive chain of 3 rows of large dark brown oval/round spots outlined in black, on a yellowish-brown or tan background - "chain viper"
• Length: 1.2-1.5 m; stout, heavy-bodied
• Head: Triangular, distinct from neck; flattened
• Pupils: Vertical elliptical (cat-eye)
• Tail: Short
• Sound: Produces loud hissing when threatened
• Retractable front fangs (viperinae type - solenoglyphous, long mobile fangs)

4. Saw-Scaled Viper (Echis carinatus)

• Size: Smallest of the Big Four - only 30-70 cm
• Color: Sandy brown/grey with white or pale spots and a pale dorsal zigzag or arrow-head pattern
• Scales: Keeled lateral scales with a saw-like edge - rubs them together to produce characteristic sizzling/rasping sound (unlike Russell's hissing)
• Head: Pear-shaped, distinct from neck; snout rounded
• Pupils: Vertical elliptical
• Habits: Coils into C- or figure-8 shape; sidewinding motion
• Retractable fangs (viperinae type)

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PART 2: FANG MARK PATTERNS

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PART 3: VENOM TYPES AND MECHANISMS

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PART 4: CLINICAL FEATURES - DIFFERENTIATION

ELAPID BITES (Cobra + Krait) - Predominantly Neurotoxic

Indian Cobra (Naja naja)

• Burning pain at bite site
• Significant local swelling, redness, necrosis (cytotoxin)
• Blister formation, tissue gangrene possible
• Regional lymphadenopathy

• Ptosis (drooping eyelids) - EARLIEST and most reliable sign
• Ophthalmoplegia, diplopia
• Difficulty swallowing (dysphagia), drooling
• Dysarthria, facial muscle weakness
• Descending paralysis following cranial nerve involvement
• Respiratory paralysis (terminal - diaphragm involved last)
• Pupillary reflexes preserved until late
• Deep tendon jerks preserved until late
• Some patients progress to coma within 2 hours
• Cardiotoxicity: tetanic cardiac contraction (rare, high-dose)

Common Krait (Bungarus caeruleus)

• Bite marks barely visible - no pain, no swelling
• Patient may not even wake up if bitten during sleep

• Abdominal colic, vomiting, diarrhea (early pre-paralytic symptoms)
• Ptosis, ophthalmoplegia
• Progressive ascending or descending paralysis
• Respiratory failure - main cause of death
• No local tissue effects distinguishes krait from cobra
• Symptoms that portend paralysis: repeated vomiting, blurred vision, paraesthesiae around mouth, hyperacusis, headache, dizziness
• Pre-synaptic mechanism means neostigmine/anticholinesterase therapy is LESS effective (vs cobra)

VIPERINE BITES (Russell's + Saw-Scaled) - Predominantly Hemotoxic

Russell's Viper (Daboia russelli)

• Immediate severe burning pain
• Rapid, massive local swelling
• Ecchymosis, blistering, hemorrhagic bullae
• Tissue necrosis and gangrene
• Regional lymphadenopathy

• Hemotoxic: spontaneous bleeding from gums, nose, GIT (haematemesis, melaena), urinary tract, injection sites
• Petechiae and purpura
• DIC - consumption coagulopathy (activates factors V and X)
• Massive intravascular haemolysis (especially in India and Sri Lanka)
• Acute kidney injury (ARF) - major cause of death; common in ~1/3 of cases
• Intracranial haemorrhage (subarachnoid, subdural, extradural)
• Cardiovascular: tachycardia, hypotension, ECG changes (25% of viperine bites), rarely acute MI
• Neurotoxicity: ptosis and ophthalmoplegia can occur (Russell's viper has neurotoxic components in some South Asian populations)
• Hypopituitarism (Sheehan-like syndrome) - delayed complication
• Bilateral thalamic haematoma (rare)

Saw-Scaled Viper (Echis carinatus)

• Moderate local pain and swelling
• Less extensive tissue necrosis than Russell's

• Defibrinogenation syndrome - spontaneous systemic bleeding
• 20-WBCT (20-minute whole blood clotting test) positive - blood remains unclotted
• Thrombocytopenia
• Coagulopathy can occur with delayed onset (hours)
• Renal failure (less frequent than Russell's)
• Generally fewer local effects and less severe systemic manifestations than Russell's

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PART 5: KEY DIFFERENTIATING CLINICAL TABLE

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PART 6: BEDSIDE INVESTIGATIONS

1. 20-minute Whole Blood Clotting Test (20-WBCT): Place 1-2 mL venous blood in a dry glass tube; leave undisturbed 20 min; invert - if still liquid = coagulopathy (positive in Russell's + saw-scaled viper bites)
2. CBC: Thrombocytopenia, haemolysis, anaemia
3. PT/INR, aPTT, fibrinogen, D-dimer: For coagulopathy
4. Serum creatinine, urea: Renal function
5. Urine for blood/myoglobin: Haemoglobinuria, myoglobinuria
6. Creatine kinase: Rhabdomyolysis
7. ECG: Cardiac arrhythmias
8. Urine output monitoring: Oliguria/anuria in ARF
9. Blood group and cross-match

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PART 7: MANAGEMENT

First Aid (Prehospital)

• Reassure and calm the patient (panic accelerates venom spread)
• Immobilize the bitten limb below heart level
• Pressure immobilization technique (for elapid bites especially): firm bandage from bite site upward, then splint - traps venom in lymphatics until antivenom available
• Remove rings, watches, tight clothing from bitten limb
• Transport rapidly to hospital
• Do NOT wash bite site (venom traces can identify the snake)
• Mark time of bite

• Cut and suck the wound
• Apply electric shock
• Apply ice
• Give NSAIDs/aspirin (risk of bleeding in viperine bites)
• Apply tourniquet in viperine bites (risk of embolism when clot released + concentrated local venom damage)

Hospital Management

Initial Assessment

• Secure IV access; two large-bore cannulas
• Airway assessment - early intubation if neurotoxic signs
• Mark swelling margins and measure limb circumference every 15 min
• Monitor vital signs, urine output
• Send bloods (as above)

Indications for Antivenom

• Neurotoxicity: ptosis, ophthalmoplegia, paralysis, respiratory failure
• Haemotoxicity: spontaneous bleeding, coagulopathy (abnormal 20-WBCT, low fibrinogen)
• Cardiovascular: hypotension, shock, arrhythmias
• Acute kidney injury / oliguria
• DIC, rhabdomyolysis

• Swelling involving >half the affected limb
• Extensive bruising or blistering
• Rapid progression of local lesion within 30-60 min

Antivenom Administration

• Children receive same dose as adults (venom load is the same)
• Infuse slowly initially (1 mL/min x 10 min), then at 2-4 mL/min
• Repeat dosing if features persist or recur after 1-2 hours
• Antivenom works best on circulating venom - it cannot reverse established tissue necrosis

• Early (anaphylaxis): epinephrine (0.5 mL 1:1000 IM), antihistamines, corticosteroids; stop infusion, then restart slowly
• Late (serum sickness 5-10 days): oral corticosteroids 5 days

Specific Treatments by Snake

Neostigmine Protocol (for neurotoxic bites):

• Test dose: Edrophonium 10 mg IV (or atropine 0.6 mg IV first, then neostigmine 1.5-2 mg IM)
• If improvement in ptosis within 5-10 min = continue
• Maintenance: Neostigmine 0.5-2.5 mg IM every 30-60 min + atropine 0.6 mg to prevent muscarinic side effects
• Monitor for respiratory failure regardless

Management of Complications

• Conservative management first (fluid balance, strict I/O)
• Peritoneal dialysis or haemodialysis if oliguria persists
• Avoid nephrotoxic drugs

• Antivenom is primary treatment
• FFP and cryoprecipitate after antivenom (not before - will be consumed)
• Heparin for DIC - use with caution given bleeding risk
• Blood transfusion for significant haemorrhage

• Early intubation + mechanical ventilation
• Neostigmine as adjunct for post-synaptic neurotoxicity
• Prolonged ventilation may be needed (days to weeks for krait bites)

• Saline cleaning, sterile dressing
• Tetanus prophylaxis
• Antibiotics: not routine; if indicated - cotrimoxazole, fluoroquinolones ± metronidazole
• Early surgical debridement if necrosis
• Fasciotomy generally more harmful than useful; avoid unless true compartment syndrome confirmed

• Steroids (do not reduce necrosis severity)
• Prophylactic antibiotics (unless evidence of secondary infection)

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PART 8: SEVERITY GRADING

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PART 9: CAUSES OF DEATH

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