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).
BIBLIOGRAPHY
Boys, Floyd and Hobart M. Smith. Poisonous Amphibians and Reptiles. Charles C. Thomas Co., Springfield, 1959.
Brown, Bryce C. An Annotated Check List of the Reptiles and Amphibians of Texas. Baylor University Press, Waco, 1950.
Buckley, Eleanor and Nandor Porges (Editors). Venoms. Publication No. 44, American Association for the Advancement of Science, Washington, D. C., 1956.