Snakebite Treatment & Management

Treatment is based on the severity of envenomation; it is divided into field care and hospital management.

Prehospital Care

• As with all medical emergencies, the goal is to support the patient until arrival at the emergency department. The dictum " primum no nocere " (first, do no harm) has significant meaning here because many poorly substantiated treatments may cause more harm than good, including making an incision over the bite, mouth suctioning, tourniquet use, ice packs, or electric shock.
• Appropriate field care should adhere to the basic tenants of emergency life support.
• Reassure the patient during the implementation of ABCs.
• Monitor vital signs and establish at least one large-bore IV and initiate crystalloid infusion. Administer oxygen therapy. Keep a close watch on the airway at all times in case intubation becomes necessary.
• Restrict activity and immobilize the affected area (commonly an extremity); keep walking to a minimum.
• Negative-pressure suctioning devices offer some benefit if used within several minutes of envenomation. Again, do not make an incision in the field.
• Immediately transfer to definitive care.
• Do not give antivenin in the field.

Emergency Department Care

• Physicians who have little experience treating snakebites frequently care for such patients.
• Regional centers often have more experience in the care of snakebite victims. Surgical evaluation for an envenomation victim is paramount.
• Definitive treatment includes reviewing the ABCs and evaluating the patient for signs of shock (eg, tachypnea, tachycardia, dry pale skin, mental status changes, hypotension).
• Evenomation grading determines the need for antivenin in victims of pit viper envenomations. Grades are defined as mild, moderate, or severe.

  • Mild envenomation is characterized by local pain, edema, no signs of systemic toxicity, and normal laboratory values.
  • Moderate envenomation is characterized by severe local pain; edema larger than 12 inches surrounding the wound; and systemic toxicity including nausea, vomiting, and alterations in laboratory values (eg, decreased hematocrit or platelet count). Moderate envenomation is shown in the image below. Snakebite. Moderate rattlesnake envenomation in a toddler after treatment with antivenom. Photo by Sean Bush, MD.
  • Severe envenomation is characterized by generalized petechiae, ecchymosis, blood-tinged sputum, hypotension, hypoperfusion, renal dysfunction, changes in prothrombin time and activated partial thromboplastin time, and other abnormal test results defining consumptive coagulopathy.
• Grading envenomations is a dynamic process. Over several hours, an initially mild syndrome may progress to a moderate or even severe reaction.
• Horse-serum antivenin has been available since 1956; a purer antivenin with improved properties was released in 2000 (see Medication). With the reduced side-effect profile of antigen-binding fragment antivenom (FabAV) and the improvement in tissue injury with antivenin administration, the threshold for dosing is lower. One study from the southwest United States demonstrated a reduction in rate of fasciotomy after more liberal FabAV dosing.^[5] In a randomized study of scheduled versus as-needed FabAV dosing in patients whose symptoms were worsening, the Rocky Mountain Poison and Drug Center demonstrated a reduction in pain and other venom effects but noted a 20% acute and 23% delayed drug reaction.^[6]
• Although copperhead bites are generally self-limiting, morbidity was reduced in moderate envenomation 4 hours after 4 vials of FabAV in 88% of cases. The cases that failed to respond were not changed by further FabAV doses.^[7]
• FabAV is generally considered safe for children, as many of the studies did not discriminate in age. One large study from Mexico demonstrated no immediate or late allergic reactions to FabAV when administered according to grade of envenomation.^[4]
• Give antivenin for coral snakebites as a standard of care if the patient presents within 12 hours of the bite, regardless of local or systemic signs. Neurotoxicity may develop without warning and lead to respiratory failure.
• Although FabAV helps control local tissue effects and hemotoxicity, aggressive antivenom therapy does not usually ameliorate neurotoxic effects such as myokymia (spontaneous, fine fascicular contractions of muscle without muscular atrophy or weakness) and major muscle fasciculations. The physician must maintain continuous monitoring of those patients with myokymia especially of the shoulders, chest, and diaphragm for the development of respiratory failure and need for mechanical ventilation.^{[8, 9]}

• Surgical assessment focuses on the injury site and concern for the development of compartment syndrome.

  • Fasciotomy is indicated only for those patients with objective evidence of elevated compartment pressure.
  • Liberal monitoring of compartment pressure is warranted. If this is not available, utilize the physical hallmark of compartment hypertension (pain with passive range of motion), along with distal pallor, paresthesia, or pulselessness for the clinical assessment.
• Tissue injury after compartment syndrome is not reversible but is preventable.

• Contacting the poison control center is important.
• Consultation with a surgeon often is warranted in bite management. General and trauma surgeons often have experience with envenomation, resuscitation, complications, and wound care. They can lead the inpatient treatment.