Allay anxiety and fright

Deaths have been reported from shock due to fright even when the bites were by non-poisonous snakes. Hence, it is vital to reassure patients.

• Not all snakes are poisonous.
• Not all poisonous snakes are fully charged with venom.
• Even those that are fully charged do not always inject a lethal dose.

Reassurance helps reduce anxiety related high. blood pressure, palpitations, tremors, sweating and rapid breathing.

Check if the bite is due to a poisonous or a non-poisonous snake. because people who are bitten can’t always positively identify a snake, they should seek prompt care for any bite, though they may think the snake is nonpoisonous. Even a bite from a so-called “harmless” snake can cause an infection or allergic reaction in some individuals.

In cases where the snake is killed and brought to the clinic, examination of the snake helps differentiate whether it is poisonous or non-poisonous. In the absence of the snake, the bite mark should be examined using a magnifying lens.

• If possible, try and keep bitten extremity at body level, when the person is lying. Raising it can cause venom to travel into the body. Holding it down, can increase swelling.
• Go to nearest hospital or medical facility as soon as possible
• If possible try to identify the snake and if possible kill and take the snake along to the hospital.

Under Medical Supervision

In the management of the snake bite an estimate of the severity of envenomation should be made as soon as possible, before any antivenin is administered, since, for example, in approximately 20% of rattlesnake bites, venom may not be injected.

The preferred route of administration is by intravenous infusion. However, many antivenin polyvalent may be administered intramuscularly. If the intramuscular route is used, the antivenin should be administered into a large muscle mass, preferably into the gluteal area, with care to avoid nerve trunks. It should be kept in mind that maximum blood concentrations may not be attained for 8 or more hours after intramuscular administration.

Reconstituted antivenin polyvalent may be administered intravenously in a 1:1 to 1:10 dilution in 0.9% sodium chloride injection or 5% dextrose injection. Decisions concerning the dilution of antivenin to be used, and the rate of intravenous delivery of the diluted antivenin should take into account the age, weight, and cardiac status of the patient; the severity of the envenomation; and the interval between the bite and the initiation of specific therapy.

The entire initial dose of antivenin should be administered as soon as possible, preferably within 4 hours after the bite. Antivenin is less effective when given 8 hours or more after envenomation and may be of questionable value when given after 12 hours. However, in severe poisonings, it is recommended that antivenin therapy be given even if 24 hours have elapsed since the bite.

The initial 5 to 10 ml of the diluted antivenin should be infused over a 3 to 5 minute period, with careful observation of the patient for evidence of an untoward reaction If no symptoms or signs of an immediate systemic reaction appear, infusion of the diluted antivenin may be continued at the maximum rate considered safe for intravenous fluid administration.

The decision to use additional antivenin should be based on the clinical response to the initial dose and on continuing assessment of the severity of poisoning. If swelling continues to progress, if systemic symptoms or signs of envenomation increase in severity, or if new manifestations appear (for example, fall in hematocrit or hypotension), intravenous administration of an additional 10 to 50 ml (contents of 1 to 5 vials) or more may be necessary.

Pit viper bites on toes or fingers may require as much as 50% more antivenin due to difficulties in achieving adequate antivenin concentrations in the affected area.

Administration of anti-venom:

Polyvalent anti-snake venom contains antibodies against cobra, common krait and viper.
5 vials are given if signs are mild -primarily local manifestations.
10 vials if signs are moderate -bleeding from gums, ptosis.
15 vials if signs are severe -vascular collapse, progressive paralysis.

1/3 of the dose should be given subcutaneously (near bite but not in fingers or toes).
1/3 intramuscularly.
1/3 intravenously.

The intravenous dose can be repeated every 6 hours till the symptoms disappear. For sea-snake bites, special antivenins are available.

Manage toxic signs/symptoms:

Anti-venom acts only against circulating toxin, not toxin fixed to tissue. Therefore, specific measures have to be taken.
In case of neuro toxic signs and symptoms, atropine (0.6 mg) subcutaneously should be followed by 5 injections of neostigmine (0.5 mg) intravenously (repeated 2 hourly depending on response) to reverse muscle paralysis.
In case of vasculotoxic signs and symptoms, fibrinogen along with heparin may be given, but with extreme caution and constant monitoring, as heparin can intensify bleeding.

Take supportive measures:

These include blood or plasma transfusion to combat shock,
mechanical respiration to combat respiratory distress,
antibiotics to prevent secondary infection. Neuromuscular paralysis is the most dreadful complication of snake bite. It may occur within 15 minutes but may be delayed for several hours.
To tackle hypersensitivity reactions to antivenom, steroids, adrenaline and antihistamines may be given.