perfusion is necessary because of progressive edema; the constriction band should be shifted to remain proximal to the swelling To be effective, the band must be applied initially within hour of the pit viper bite It may be removed when antivenin therapy is started Incision and suction (extractors) of the pit viper wound is no longer advised The usefulness of extractors can be supported only if applied within minutes of the bite and even then, recovery of venom is variable in the laboratory setting Animal studies not demonstrate an increase in survival In the rare situation in which skilled personnel and supplies are at the scene and a long transport is expected, it is reasonable to allow one or two attempts at IV access Many authorities also suggest capturing or killing the snake for later verification, but again, prudence dictates that time not be wasted and that an inexperienced person not risk the bite of an agitated snake If the snake arrives in the ED, treat it with respect—decapitated snakes can bite reflexively for up to hour Management If the history and physical examination on arrival in the ED are consistent with a venomous snakebite, immediate laboratory evaluation and IV access are indicated A CBC, coagulation studies, platelet count, urinalysis, and blood crossmatching should be obtained, as blood may be difficult to crossmatch after massive hemolysis In moderate or severe poisoning, analyses of serum electrolytes, BUN, creatinine, liver function tests, creatine kinase, fibrinogen, and ABG are also indicated Hemolysis, anemia, thrombocytopenia, hypofibrinogenemia, prolonged bleeding times, and metabolic acidosis all may be seen in severe poisoning Repeat the laboratory studies every hours to ensure no significant changes occur For patients with complaints of chest pain, a 12-lead ECG, a chest radiograph, and troponin levels should be ordered Patients require serial comprehensive neurologic examinations If there is a concern for a hemorrhagic cerebrovascular accident, a noncontrast CT scan of the head should be obtained Similarly, when intra-abdominal bleeding is suspected with the presence of abdominal tenderness or distention, clinicians may consider an abdominal ultrasound or CT scan Therapy will be based on the clinician’s overall grading of venom toxicity Local and systemic manifestations, as well as laboratory findings, weigh heavily in this judgment The clinical pattern may change as the venom’s effects unfold and frequent reassessment is crucial The physician should measure and record the circumference of the injured extremity at the leading point of edema and 10