Snakebite: First aid & treatment

Snakes are the most dreaded organism irrespective of the toxicity. Snakes are elongated legless, carnivorous reptiles which frighten the public a lot. They are encountered in all kinds of geographic areas such as land, marshes, water. Snakes are predominantly encountered in agricultural areas but also found among urban population due to excavations, ongoing construction work and water filled pits and holes, which forces the snakes to come out.

Snakebites account for 5.4 million bites every year, 2.5 million fatalities and 1.25 million deaths annually. Snake bite injects venom with each bite, which is responsible for various effects in the body. Though many deaths occur due to envenomation, significant few occur due to terror following bite.

What are the effects of snake venom?

Snake venom contains complex proteins which causes hemorrhage, tissue edema, tissue necrosis, ptosis, paralysis. Each Snake bite injects approximately 63mg of Venom.

There are 2 types of toxicities seen with snake bites:

1. Hemorrhagic toxicity seen with Viper bite. Hemorrhage, Tissue Necrosis, Disseminated Intravascular coagulation, Hemoptysis, Hematemesis, Hematuria, Renal failure

2. Neurotoxicity seen with Cobra Bite. Ptosis, External Ophthalmoplegia, Dysphagia, Flaccid Quadriparesis, Neck Muscle Weakness, Respiratory paralysis, Respiratory Depression.

Types of anti-snake venom available in India

In India, only Polyvalent Anti Snake venom is available which is effective against lethal four snakes i.e., Cobra, Viper, krait, Saw scaled viper. Each vial of ASV can neutralise 6mg of Cobra, Viper venom each and 4.5 mg of Krait and saw scaled viper venom. On an average, each snake bite requires 10-12 vials for neutralising the venom. The dose of ASV is same for pregnant mother and children. It doesn't vary according to the bodyweight

Can ASV be given even before reaching hospital?

Many gated communities are trying to store ASV with the fear of snakebite. It is not advisable to give ASV without the supervision of a qualified physician as ASV is prone to cause many allergic reactions and can cause anaphylactic shock as well. ASV should be stored below 8C temperature and the effect will be lost if exposed to room temperature for long period. ASV is available in the powder form which needs to be reconstituted into clear liquid form and further diluted in 500ml of IV fluid before injecting. ASV should be given as soon as possible but there is no time limit to administer ASV. It is given as long as coagulopathy persisits upto 1 week or more in some instances.

What are the treatment modalities?

There are 4 types of treatment we provide to the victims of snakebite: Physiological Antidote: by giving ASV to neutralise the venom; Pharmacological Support: Neostigmine/ Atropine/ CalciumGluconate for addressing ptosis, Bradycardia or myocardial Depression; Mechanical ventilation support: for Respiratory Depression; and, Local Treatment for the wound: with appropriate dressings to prevent further local tissue damage.

The successful outcome of the snakebite depends on the conglomerate of all the above treatments and not dependent on the ASV use alone.

(Writer is Senior Consultant, Academic Director & HOD, Institute of Trauma & Emergency Medicine, Continental Hospitals)

By Dr Sree Sowjanya Patibandla