Define Snakebite. Describe its types, clinical features, management and complications.

Definition

Snakebite envenomation is a medical emergency. In India, the medically important venomous snakes are the 'Big Four' — cobra, krait, Russell's viper and saw-scaled viper.

Types of Venom & Effects

Clinical Features

• Local — fang marks, pain, swelling, blistering, necrosis (vasculotoxic).
• Neurotoxic — ptosis (early), diplopia, dysphagia, and descending respiratory-muscle paralysis.
• Haemotoxic — spontaneous bleeding, incoagulable blood, and acute kidney injury.
• 20-minute whole-blood clotting test (20WBCT) — a simple bedside test for coagulopathy (viper bites).

First Aid

• Reassure, keep the patient still, and immobilise the bitten limb (splint) at heart level.
• Remove tight items (rings/bangles); transport urgently to hospital.
• Avoid tourniquets, incision, suction and traditional remedies (harmful).

Hospital Management

• Anti-snake venom (polyvalent ASV) for signs of systemic envenomation or severe local envenomation.
• Neurotoxic envenomation — atropine + neostigmine (anticholinesterase) and airway/ventilatory support.
• Haemotoxic — repeat ASV guided by the 20WBCT, manage bleeding and AKI (dialysis if needed).
• Monitor for ASV reactions (have adrenaline ready); wound care and tetanus prophylaxis.

Differentiating Bites

• Dry bite — no envenomation (no local/systemic signs); observe.
• Local envenomation — pain, swelling, necrosis; systemic — neurotoxic or haemotoxic features (need ASV).

Asv Reactions

• Anaphylactic reactions to ASV are common — monitor closely and keep adrenaline ready.
• Pyrogenic and late serum-sickness reactions can also occur.

Complications & Prognosis

• Respiratory failure (neurotoxic), acute kidney injury and bleeding (haemotoxic), local necrosis/compartment syndrome.
• Early ASV and good supportive/ventilatory care greatly improve outcome.

Investigations

• 20-minute whole-blood clotting test at the bedside; coagulation profile, platelets.
• Renal function and urine output (AKI), CBC, and monitoring of neurological/respiratory status.

Supportive Care

• Airway/ventilation for neurotoxic paralysis; blood products for significant bleeding; dialysis for AKI.
• Wound care, tetanus prophylaxis, and treatment of secondary infection.

Prognosis

With early anti-snake venom, airway/ventilatory support for neurotoxic bites, and management of coagulopathy and AKI for viper bites, most patients recover; delay is the main determinant of death and disability.