The World Health Organization (WHO) estimates there are up to 1.8 million bites from venomous snakes annually worldwide, causing 20,000-90,000 deaths.
Snake venom has been described as a "soup of antigens" and comprises a variety of protein and nonprotein substances. Most crotalid venom contains a mixture of metalloproteinases, collagenase, phospholipase, and hyaluronidase that can cause myonecrosis and dermatonecrosis. Multiple venom components, such as serine proteases, disintegrins, metalloproteinases, and C-type lectinlike proteins, produce a variety of hematologic effects, resulting in coagulopathy, platelet aggregation, platelet activation or platelet inhibition, or increased coagulation, leading to thrombotic complications.
The goals of pharmacotherapy in the treatment of snakebite are to alleviate pain, prevent paralysis, minimize tissue damage, correct hematologic toxicity, and maintain adequate perfusion.
Severity of Envenomation
Dry bites: These occur when there is no venom deposition, and therefore there are no signs or symptoms beyond a puncture wound. It is estimated that less than 10% of pit viper bites and 30-50% or coral snake bites are dry.
Minimal envenomations: These are characterized by local findings such as bruising, tenderness immediately adjacent to the bite site, and an absence of laboratory abnormalities and systemic findings.
Mild envenomations: These also lack laboratory abnormalities and systemic findings, but the local damage extends several centimeters from the bite site, all the way to a major joint (eg, ankle, wrist).
Moderate envenomations: These may be associated with non–life-threatening signs and symptoms (eg, vomiting, hematotoxicity without bleeding) and/or local damage that extends beyond two joints.
Severe envenomations: These result in extensive local damage (eg, beyond two joints) and/or significant systemic toxicity (eg, hypotension, airway swelling, muscle paralysis).
Give the first dose (10ml)of antivenom intravenously at a slow rate of 1-2ml per minute. Subsequent doses may be injected into a bag of saline drip,no more than 20ml per 500ml bag to run in 30mins. REPEAT UNTIL SYMPTOMS RESOLVE.
Monitor breathing and other vital signs continously.
Remember not to have the drip running direct into the wounded limb which is already in danger of pressure from the swelling and should be kept elevated and well protected.
Remember to have adrenaline (1:1000) at the bedside in case of anaphylaxis.If the patient is known to have allergies,draw up the adrenaline and have antihistamines available incase allergy symptoms become overwhelming.
Antihistamine is not considered as routine treatment for snake bites.
Do not infiltrate the bite area with antivenom.
Antivenom is not indicated if the patient is asymptomatic.
Snakes do not harbor Clostridium tetani in their mouths, and the risk of acquiring tetanus following snake envenomation is exceptionally low. That said, if a patient's tetanus immunization is not current, a TDaP should be administered while the patient is being evaluated. However, tetanus immunoglobulin in unnecessary.
Diphtheria-tetanus toxoid is used to induce active immunity against tetanus in selected patients. The immunizing agents of choice for most adults and children older than 7 years are tetanus and diphtheria toxoids. It is necessary to administer booster doses to maintain tetanus immunity throughout life.
Pregnant patients should receive only tetanus toxoid, not a product containing the diphtheria antigen.
In children and adults, one may administer into the deltoid or midlateral thigh muscles. In infants, the preferred site of administration is the mid thigh laterally.
proper elevation of an affected extremity. Notice that this is loosely applied so there is no obstruction to lymphatic flow.
Comments
Post a Comment