Case of Snake Bite

Case Scenario:

In the flood affected area of Badin, a bare footed young man of 10 years age,  while walking in the dark at night felt that some unknown creature has bitten on his left foot. He was taken to the medical camp where her complained of pain and dizziness. On examination two sharp fang marks were noted. It is a suspected case of snake bite warranting immediate treatment.

Learning Objectives:

Students should be able to learn:

1. Types of snakes  and their identification
2. Mode of action of different snake venoms
3. Anti-snake venom
4. Management of snake bite case
5. Public Health measures to prevent snake bites.

Tasks:

Following will the tasks completed by the students:

1. To identify the poisonous and Nonpoisonous snakes.
2. How to treat a case of snake bite in the fields.

Solution:

Type of Snakes and their Classification:

There are two types of snakes i.e.

• Poisonous or Venomous Snakes (10%)
• Non Poisonous or Non Venomous Snakes (70-90%)

Mode of Action of Different Snake Venoms

• Hemolytic Toxins
• Neurotoxins
• Myotoxins

Management of Snake Bite

Immediate Measures:

1.      Allay anxiety, reassure patient, remove tight clothing.
2.      Examination of bite site.
3.      Identification of snake
4.      Clinical assessment of snake bite

History, physical examination and diagnosis

5.      First aid methods

Traditional: cut and suck, cold-pack method (obsolete now)

Newer technique: electric shock treatment

6.      Specific measure: Antivenom therapy.
7.      Supportive measures: bed rest, warm bottles, analgesics and sedatives, blood transfusion, ventilation support.

Public Health Measures to Prevent Snake Bite

1. Wear jean high boots while walking in grass, water etc
2. Use lantern, torches when walking in fields.
3. Don’t put hands in hollow dugs and burrows.
4. Mass public education to reduce morbidity and mortality.

Anti-snake Venom

Anti-snake venom is immune serum extracted from horse which neutralize the effect of snake venom when injected as specific treatment.

Dosage: 20-50ml diluted in 5 time s volume of normal saline.

Identification of Poisonous and Nonpoisonous Snake:

Belly:

Small scales not extending whole breadth= non poisonous

Large scales whole belly breadth= poisonous

Head:

Small scales = poisonous

Large scales = non poisonous

Side of Head:

Pit between eyes and nostrils = poisonous

3^rd labial touches eyes and nasal shield = poisonous

Management

Field Management

• Alleviate anxiety, reassure the patient.
• Look for evidence of snake bite.
• Don’t let the patient move. Immobilization of the bitten part/limb is useful technique to reduce venom transport.
• Hold bitten part at or below the level of heart.
• Pressure immobilization in which entire limb is wrapped with a bandage and then splinted.
• Other first aid methods of no. value or which are potentially harmful include:

1. Tourniquets
2. Cutting and suction method of wounds.
3. Application of chemicals.
4. Use of cryotherapy or electric shock.

NOTE:

If using B.P. apparatus, pressure applied should be between systolic and diastolic B.P. Cut and suction method obsolete now due to following reasons:

1. More venom enters
2. Bleeding
3. Chances of more infection

Scorpion bite is very painful and local anesthetic has to be given to relieve pain. In rare cases, scorpion bite can be fatal (e.g. when multiple bites). Treatment given is to relieve pain.

In Pakistan:

Total snake bites per year= 25-40000

Total deaths per year =    2660

a) History Taking:

• Time of bite
• Description of snake
• S/S since injury
• H of exposure to horse serum.

b) Examination (general and systematic)

Examine site of bite

c) Urine microscopy and Urine D.R Done

Bleeding first seen as microscopic hematuria

d) Skin Sensitivity to Horse Serum

e) CBC

f) Blood Typing and Cross-matching

Specific Measures:

Anti-venom therapy is given.

a) Sensitivity Test:

20-25ml diluted with 5 times its volume of physiologic saline. Given 1/V in 30-45 minutes. If patient is hypersensitive to antivenin we give antivenin (slowly in diluted form) along with epinephrine and corticosteroid. Aspirin not given since it has anti-platelet activity. Paracetamol can be given to relieve pain.

b) Supportive/ Symptomatic Measures:

Rest in bed, warmth, analgesics, and sedatives.

• Shock: Fluid and electrolyte balance blood transfusion (whole blood).
• Ventilation Support: O2 is helpful
• Antibiotics: To prevent secondary infection.
• Tetanus Prophylaxis
• Heparin: (for DIC)
• Steroids: (to overcome side effects of antivenin method)