snake bites

Signs and management done by Udawattage Geewan Kamal

SNAKE BITES

It is estimated that there are about 5 million snake bites every year, of those it’s estimated around 2.4 million are envenoming

These snake bites cause around 94 000 to 125 000 deaths annually with an additional 400 000 amputations and other consequences -infection, tetanus, scarring, contractures, and psychological sequelae

Most snake bites are caused by non-venomous snakesOf the roughly 3000 known species of snake found worldwide,

only 15% are considered dangerous to humansSnakes are found on every continent except Antarctica

Introduction

In Sri Lanka there are about 65 000 snake bites annuallyMore people die of snake bite in Sri Lanka than in any

other comparable area in the worldAn average of 800 people are killed by snakes every year

on the 656,120Km² (25,332miles²) island - equivalent to one person every 82Km² (32 miles²) annually

Over 95% of the fatalities are caused by the common krait (Bungarus caeruleus), the Sri Lankan cobra (Naja n. naja) and Russel's pit viper (Vipera russelli pulchella)

Snake Venom : Snake venom is made up of more than 20 different

compounds, mostly proteins and polypeptides Procoagulant enzymes (activate coagulation cascade) Phospholipase A2 (myotoxic, neurotoxic, cardio toxic – cause

hemolysis, increase vascular permeability) Proteases (tissue necrosis) Polypeptide toxins (disrupt neuromuscular transmission)

Lethal dose of venom of certain snakes : Cobra-0.12gm, Krait0.06gm- Russell’s V-0.15gm

Highly venomousRussell’s viperHump-nosed viperSaw scaled viperSea snakeCobraCommon kraitCeylon krait

Snakes of Sri Lanka

Russell’s viper

Hump nosed viper

Sea snake

Cobra

Ceylon krait

Moderately venomousCat snakeGreen-pit viper

Non-venomous snakesRat snakeWolf snake

Signs and Symptoms

Puncture mark or scratches on suspected bite area. At times marks could not be visible

Bleeding at bite site, unusual pain around the bitten area and limb, swelling

Nausea, headache, vomiting , stomach ache, difficulty in swallowing or drinking

Double or blurred vision Drooping eyelids Difficulty in talking. Bleeding in gums. Dark or brownish urine bloody urine. Giddyness

Common envenomation signs and symptoms The following are few of the most common symptoms of envenomation due to a snake bite. Symptoms may occur soon after the bite or take hours to appear. A minimum of twenty-four hour observation of the patient is suggested.

These images of actual bite marks by venomous snakes show that marks may or may not be clearly visible.

Bite marks dependent on the type and size of snake in question.

Common locations of snake bites

Drooping eyelids

Change in color of tissue around the bite area

Swelling in the limb

Blisters in the bite area

Signs and symptoms of a venomous snake bite

Diagnosis Between Different Species Using Symptoms

Envenoming

Local Systemic

Specific Non Specific

Fang marksLocal painLocal bleedingBruisingLymphadenitisInflammation (swelling, redness, heat)BlisteringLocal infection Necrosis

Local

Cardiovascular signs and symptomsBleeding and clotting disordersNeurotoxicityRhabdomyolysis with myoglobinuriaRenal

Systemic – Specific signs

Nausea VomitingMalaiseAbdominal pain WeaknessDrowsiness

Systemic – Non specific signs

Snake type Local reaction clotting Neurological Renal

Russell’s viper + + + +

Hump nosed viper

+ + +

Saw scaled viper

+ +

Cobra ++ +

Krait +

Sea snake +

Attempt to retard systemic absorption of venomPreserve life and prevent complications before the patient can

receive medical careControl distressing or dangerous early symptoms of

envenomingArrange the transport of the patient to a place where they can

receive medical care

Aims of first aid

Anti-venom is the only specific antidote to snake venom A most important decision in the management of a snake bite victim is whether

or not to administer anti-venom Indications for anti-venom. Anti-venom treatment is recommended if and when a

patient with proven or suspected snakebite develops one or more of the following signs

1. Systemic envenoming2. Haemostatic abnormalities : spontaneous systemic bleeding,

coagulopathy(20WBCT,prothrombin time) thrombocytopenia(less than 100*109 per litre)

3. Neurotoxic signs (ptosis, external opthalmoplegia, paralysis)4. Cardiovascular abnormalities (hypotension, shock, cardiac arrhythmia) In Sri lanka given to all patients with systemic envenomation except in hump

nosed viper bite and sea snake bite If the snake is identified as nonvenomous patient can be discharged after a

booster dose of tetanous toxoid.

AVS

At the earliest sign of a reactionAnti-venom administration must be temporarily suspendedEpinephrine(0.1%solution,1 in 1000,1mg/ml)is the effective

treatment for early anaphylactic and pyrogenic anti-venom reactions

All patients should be watched carefully for 2 hours after the completion of anti-venom administration and should be treated with epinephrine/adrenaline at the fist sign of a reaction

Q.a farmer presents with a history of snake bite but could not identify or kill the snake. His foot is swollen and painfull and bite site is necrotic. b/l partial ptosis. uop is normal. rft normal. 20 min wbct normal. what is the most likely snake

1. Russell’s viper2. Cobra3. Hump nose viper4. Sea snake5. Saw scale viper