Copperhead envenomation

Snake bite (pit vipers) Antivenin (Crotalidae) polyvalent, equine The entire dose should be given within 4 hours after the bite by the IV or IM route (1 vial = 10 mL) Minimal envenomation 2-4 vials Moderate envenomation 5-9 vials Severe envenomation 10-15 vials Additional doses may be required. Neutralizes the venom of rattlesnakes, copperheads, cottonmouths, water moccasins, and tropical and Asiatic crotalids. Serum sickness occurs in almost all patients who receive > 7 vials. 

Envenomation from a crotalid bite leaves one or more puncture wounds with a potential for progressive edema and ecchymosis. Crotalid venom contains a mixture of proteins, lipids, and metals. The venom forms fibrin polymers, which are susceptible to normal fibrinolysis and phagocytosis. It is represented by falling fibrinogen levels. Copperhead venom has a weak effect on this series of events in coagulation, resulting in lower morbidity after envenomation. 

Initial pain at the site of the bite may be followed with a metallic sensation in the mouth. Victims may become weak, and experience nausea, diarrhea, diaphoresis, and chills. Edema may begin around the bite area or may be delayed. Observation of the site for edema is a clue as to whether or not a dry bite has occurred that is, that no venom was injected into the site. Envenomation is most serious if venom is injected directly into joints, muscles, or veins. Hemorrhagic blisters and tissue destruction are possible. Neurotoxicity from rattlesnakes (but generally not from cottonmouths or copperheads) may be manifested as fasciculations, which are fine continuous contractions. In some cases, systemic neurotoxicity may involve respiratory failure. In the most serious cases, massive envenomation may lead to serious bleeding, hypotension, shock, multiple organ failure, and a high incidence of mortality. 

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