snake bites
TRANSCRIPT
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