Crotalid snakebites can be graded by the severity of the clinical findings.
Crotalid snakes (pit vipers):
(1) genus Agkistrodon: cottonmouths and copperheads
(2) genus Crotalus: rattlesnakes
(3) genus Sistrurus: Massauga and pigmy rattlesnakes
Grade
Envenomation
Findings
0
none
fang marks
minimal pain
I
minimal
pain
1-5 inches of edema and erythema in the first 12 hours
no systemic symptoms
II
moderate
6-12 inches of edema and erythema in the first 12 hours
systemic symptoms may be present
bloody ooze at bite site possible
III
severe
edema > 12 inches in first 12 hours
systemic symptoms
coagulation defects after pit viper bites
rapid progression through grades I and II, with immediate systemic signs and symptoms
IV
very severe
local reaction develops rapidly
edema may involve ipsilateral trunk
ecchymoses, necrosis, blebs and blisters may develop
at tightly restrictive fascial planes tension may be sufficient to obstruct venous or even arterial blood flow
Limitations:
• The number of categories is limited.
• Some patients cannot be categorized.
• The distinctions are somewhat subjective and imprecise.
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Specialty: Toxicology, Emergency Medicine, Critical Care
