Dr. Surajit Giri, a grassroots worker serving as an Anaesthesiologist and ICU physician from Assam, with experience of treating 307 snakebite victims since 2010, answers the common questions relating to snakebite management in India.

When is anti-snake venom (ASV) indicated?

ASV is only indicated when a patient develops one or more of the following signs:

1. Haematological signs

• Spontaneous systemic bleeding
• Non-coagulable blood in 20 minutes, as indicated by bedside 20-minute whole blood clotting test (20WBCT)

2. Neurotoxic signs

• Ptosis
• External ophthalmoplegia
• Dysphagia, paralysis

3. Cardiovascular abnormalities

• Shock
• Cardiac arrhythmia

4. Local signs

• Local swelling involving more than half of the bitten limb (in the absence of a tourniquet)
• Rapid extension of swelling
• Development of an enlarged tender lymph node draining the bitten limb

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How do we do 20WBCT and detect Venom Induced Consumption Coagulopathy (VICC)?

1. Place 4 ml of the patient's venous blood in a small glass tube.
2. Leave it undisturbed for 20 minutes at ambient temperature.
3. Tip the tube once.
4. If the blood is still liquid (unclotted), it means the patient is suffering from hypofibrinogenaemia. This is called Venom Induced Consumption Coagulopathy (VICC).

Note: It is important to remember that the container should be made of glass to stimulate coagulation and it shouldn’t be washed and cleaned with detergent.

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Is a skin test required?

WHO doesn’t recommend intradermal testing; neither do we do it.

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What are the adverse reactions to ASV?

As ASV is extracted from horse serum, it is bound to cause reactions. But, in our experience, we have witnessed reactions in only two patients; ranging from chills, rigors, and atrial fibrillation in a known COAD (Chronic Obstructive Airway Disease) patient. However, all reactions were treated conservatively. The patient with COAD with already a known case of atrial fibrillation cannot be considered as a case for adverse reaction to ASV.

None of our patients needed an adrenaline injection. Most often, doctors are afraid of administering ASV injection, even when an ASV injection is available at the hospital. It is important to overcome this fear. If we are systematically prepared for the possible adverse reactions, there is no reason to fear.

Adverse reactions can be categorised as early and late reactions.

Early reactions include:

1. Anaphylactic: It usually occurs within 5 minutes to 3 hours of starting ASV. The patient develops urticaria, itching, cough, nausea, vomiting, abdominal colic, diarrhoea, tachycardia etc. A few patients develop severe anaphylaxis like hypertension, bronchospasm, and angioneurotic oedema.
2. Pyrogenic: It develops within 1 to 2 hours after starting ASV. Reactions include fever, rigor, chills, low blood pressure etc. They are due to the pyrogenic contamination of ASV and diluting fluid.

Late reactions include:

Serum sickness: It develops between 1 to 12 days after ASV therapy. It includes fever, nausea, vomiting, arthralgia, arthritis, diarrhoea, itching, recurrent urticaria, myalgia, lymphadenopathy, proteinuria, neuritis, and even encephalopathy.

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How to treat early reactions to ASV

1. Stop ASV administration.
2. Administer adrenaline- 0.5 mg (1:1000 dilution) for adults and 0.01 mg/kg for children, intramuscularly (adrenaline- 1 ampoule contains 1 mg in 1 ml). The dose can be repeated in 5 to 10 minutes if the patient’s condition deteriorates. It is the drug of choice.
3. Begin Chlorpheniramine Maleate, 10 mg as slow intravenous injection over 3 minutes.
4. Administer Hydrocortisone, 100 mg, intravenously. It may prevent recurrent anaphylaxis.
5. Give Ranitidine, 50 mg slowly via IV over a period of 5 minutes.

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How to treat pyrogenic reactions

• Advise oral paracetamol and physical cooling to reduce temperature
• Begin intravenous fluid to correct hypovolaemia

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What is the treatment protocol for late reactions?

Advise oral antihistamine. If it fails to respond in 24 to 48 hours, prescribe Prednisone- 5 mg, 6 hourly for 7 days.

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What prophylaxis should one follow for ASV reactions?

It is generally not practiced and many a times, it harms the patients. Also, WHO doesn’t recommend prophylactic adrenaline, hydrocortisone, or pheniramine.

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Are there any contraindications for ASV?

There are absolutely no contraindications for ASV.

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Can there be a recurrence of systemic envenomation?

Yes, there may be chance of recurrence of envenomation within 24 to 48 hours, probably due to continued absorption of venom from the bite deposit site or after correction of shock or hypovolaemia, when blood circulation improves causing spreading of deposited venom to various organs in the body.

Another reason may be due to the redistribution of snake venom from tissue into vascular space as a result of antivenom therapy. Therefore after recovery, it is mandatory to observe the patient for 48 hours.

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What are the prior preparations needed to be done before administering ASV injection?

Any doctor can inject ASV provided he has taken the following measurements:

1. Identified the bite as caused by a venomous snake
2. Identified any of the following venom-induced symptoms in the patient:

• Pain and swelling in the bite area
• Difficulty in deglutition
• Unusual pain in the abdomen, vomiting, weakness
• Ptosis
• No blood clot till 20 minutes

3. Provided a proper explanation to family members.
4. Received written, informed consent to proceed, keeping in mind the chance of occurrence of anaphylaxis and even death.
5. Has access to all resuscitative equipment.
   1. Mandatory items:
      • Large bore canula
      • IV fluids
      • Ranitidine
      • Hydrocortisone
      • Chlorphenaramine maleate
      • Adrenaline
      • Myopyrolate (Neostigmine plus glycopyrrolate combination)
      • Ambu bag and mask
      • Oxgen
      • Oxygen delivery system
   2. Desirable items:
      • SpO2 probe
      • Airway
      • Bain circuit and mask
   3. Items that are neither mandatory or desirable; but if available, would add extra strength:
      • Laryngoscope
      • Endotracheal tube
      • Airway devices (iGel, LMA)
      • Anaesthesiologist help
6. Initiating 10 vials (100 ml) in 300 ml normal saline (NS) is advised irrespective of age- first at 6 drops per minute. If no adverse reactions are encountered, the drip can be increased to 12 to 15 drops per minute after 15 minutes. Finish in 45 to 60 minutes.
7. Advise the patient tablet Ranitidine, Chlorphenamine maleate orally to counter delayed adverse reactions to ASV.

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To read the other part in this article series, click Snakebite management: Key learnings from handling cases in Assam- Dr. Surajit Giri.

Disclaimer- The views and opinions expressed in this article are those of the author's and do not necessarily reflect the official policy or position of M3 India.

The author Dr. Surajit Giri is a Anaesthesiologist and ICU physician from Assam.