1. Tourniquet (Constricting band). A tourniquet applied following a
bite by a venomous North American snake should be removed if
envenomation seems mild or after a potent antivenin is given in
therapeutic quantity. The prolonged use of a tourniquet or of a
constricting band would increase local tissue damage due to the action
of venom and might delay the vascular transport of antivenin into
envenomated areas.
2. Incision and Suction. Substantial amounts of venom can be removed
during the first half-hour from subcutaneous deposits by incision and
suction. On the other hand, if the casualty is admitted to the
hospital one hour or more following envenomation, an attempt to remove
venom by incision and suction at the site of the bite would be of
little value. However, if marked subcutaneous pitting edema develops,
interstitial pressure can be relieved by several longitudinal
incisions extending into the subcutaneous tissues. Suction and
fasciotomy may be required at times.
Parrish (1961), using a modification of Wood, Hoback and Green’s (1955)
clinical classification of pit viper venenations, has proposed the
following guide for determining the severity of a poisonous snake bite.
This classification is based upon present signs and symptoms and the
clinical course of the patient during the first 12 hours of
hospitalization. It will be useful as a guide in treatment.
Grade O (No venenation). Fang or tooth marks present, minimal pain, less
than one inch of surrounding edema and erythema, and no systemic
involvement.
Grade I (Minimal venenation). Fang or tooth marks present, moderate
pain, from one to five inches surrounding edema and erythema in
the first 12 hours after bite, and no systemic involvement.
Grade II (Moderate venenation). Fang or tooth marks present, severe
pain, six to 12 inches of surrounding edema and erythema in the
first 12 hours after bite, with systemic involvement—nausea,
vomiting, giddiness, shock or neurotoxic symptoms present.
Grade III (Severe venenation). Fang or tooth marks present, severe pain,
more than 12 inches of surrounding edema and erythema in the first
12 hours after bite, with systemic involvement (as in Grade II).