Home > Browse Topics

<< Diagnosis And Management Of North American Snake And Scorpion Envenomations


Patients who have no findings of envenomation (dry bites/Grade 0) can be discharged after a four to six hour observation period.18 Patients who have limited local signs of envenomations but do not meet the criteria for CroFab™ need to be monitored for progression of symptoms in the ED or observation unit for a minimum of 8 to 12 hours from the time of the bite4-5,18,28 Although most patients with Crotalidae envenomations begin to manifest local symptoms within 10 minutes of a bite and virtually all have some findings within 30 to 60 minutes, there are some patients who will not manifest symptoms for several hours, although the mechanism for this is unclear.4 In those cases where the patient does not initially meet treatment criteria, observation and intermittent reassessment is critical since local findings or symptoms that would upgrade the envenomation into a treatment category may be absent initially.

Patients who receive CroFab™ are admitted to the hospital as discussed in the previous section. The half-life of CroFab™ is less than that of polyvalent antivenom. This fact, coupled with the persistent activity of the depot-style delivery of the venom, can lead to recurrent coagulopathy despite appropriate antivenom treatment.68 Such recurrence is characterized by decreased platelets, elevated prothrombin time, and decreased fibrinogen. During the initial trials, such a recurrent coagulopathy was observed only in those patients experiencing coagulation abnormalities at initial presentation. After initial treatment, this coagulopathy may be present for weeks. Therefore, post treatment, monitor those patients presenting with coagulopathy for signs and symptoms of recurrent coagulopathy after discharge every two to three days until the coagulopathy resolves48-49 Advise patients to contact their physician immediately if they experience new symptoms or unusual bruising or bleeding after hospital discharge as additional antivenom treatment may be needed.

Boyer et al recommend retreatment with two vials of CroFab™ in the event of fibrinogen level < 50mcg/mL, platelet count < 25,000, INR > 3.0, aPTT > 50 seconds, multicomponent coagulopathy, worsening trend in patients with prior severe coagulopathy, high risk behavior for trauma, or comorbidities that increase the risk of hemorrhage.49

Instruct patients to report any signs or symptoms of delayed allergic reactions or serum sickness after hospital discharge. Serum sickness is a delayed hypersensitivity reaction to antivenom characterized by fever, rash, arthralgias, and lymphadenopathy which typically begin 7 to 21 days following antivenom administration. It is much more rare with CroFab™ than with the older polyvalent antivenom (3% versus more than 80%) and responds well to a tapering course of prednisone starting at 60mg daily and tapering over seven to ten days.4,33,45 Serum sickness is the only indication from steroids in the treatment of snake envenomation.

Other Articles Similar To This One:

Emergency Stroke Care, Advances and Controversies


About EB Medicine:


Accredited By:


Endorsed By:

HONcode HONcode


Last Modified: 08/17/2017
© EB Medicine