Around the world about 5 million Snake bites takes place every year. Among which 2.5 million poisonings and 20 to 125000 deaths occur.Snake Bite is known as the neglected tropical disease and is an important medical emergency.There are 3000 species of snakes in the world, out of which only 15% are venomous, all others considered non venomous.Types of snakes and snake bite management have been described in this aurticle.
The most common venomous snakes found in South Asia including Pakistan are,
1_ Indian cobra
2_ Common krait
3_ Russell's viper
4_ Saw scalded viper
Signs and symptoms of snakes bite
The snake venom is composed of hundreds of different proteins and enzymes that predominantly maybe,
1.Neurotoxic
2.Haemotoxic or
3.Combination of both
The most common symptom of all Snake Bites is overwhelming fear with unwarranted thoughts of imminent death that contributes to symptoms secondary to envenomation.These non specific symptoms include,
_Nausea vomiting
_diarrhoea
_fainting
_vertigo
_tachycardia
_cold clammy skin
The signs and symptoms may be localised or systemic
Local effects
these depends on the location and severity of snakes bite.There may be mild pain and redness around the bite but in cases of vipers and cobras there may be severe pain and tenderness with marked swelling of the bitten area within five minutes.
Systemic effects
They're of three types
1_ Haemotoxic
Certain venoms can lead to a wide range of haematological effects including severe hemolysis and Disseminated intravascular coagulation (DIC), which can lead to severe anemia and bleeding diathesis.This can manifest as spontaneous bleeding in the form of patechial or purpuric rash, epistaxis, bleeding gums, bleeding from venipuncture or cannula sitesor GI bleed including hematemesis and hematochezia.
2_ Neurotoxic effects
Neurotoxic venoms can result in ptosis, blurred vision, diplopia, dysarthria, dysphagia and also feeling of suffocation.If not handled timely then the patient can die of Respiratory failure.
3_ Cyolytic effects
Some venoms produce both hemotoxic and Neurotoxic effects, They can lead to extensive cellular deaths resulting in massive myoglobinuria and shock which can precipitate acute renal failre secondary to acute tubular necrosis.
Management of snakes bite:
First aid Guide lines
* Protect the person and others from further bites while snake identification is desirable in certain regions.
Here this must be added that the locally practiced treatments may cause more harm than good, including making an incision over the bite, mouth suctioning,tourniguet use, ice packs or electric shock.
* Keep the patient calm and reassure them, as this is most important ( as 70% of all snake bites are from non_venomous species and approximately half of the bites from venomous species are dry bites that rarely poison the person.
* Washing the wound with soap and copious water and holding the limb still is recommended.
Pressure immobilization technique.
Immobilise the patient as a whole especially the bitten limmb.To do this, use bandages or cloth to hold the splints, with care taken not to apply excessive pressure that might block the blood supply. The objective of PIT is to contain neurotoxic venom within a bitten limb and prevent it from moving through the lymphatic system to the vital organs.
Hospital management
* ABC *
Maintain Airways, Breathing and Circulation
* Look for signs of shock ( tachypnea, tachycardia, dry pale skin mental status changes, hypotension)
*Prophylactic antibiotics ( 3rd generation cephalosporins are a good choice)
*Pain management (Paracetamol or norcotic analgesics But avoid NSAIDs and intramuscular injections)
*Administer snake antivenom and then elevate the swollen limb to reduce edema.
*Tetanus prophylaxis
*Keep monitoring until the patients are hemodynamically stable.
** The envenomed patients must be kept under observation for at least 3_4 days because serum half lives of most of the snake venoms range from 26_95 hours**
By Dr Sher jahan
