Supportive Care & Ongoing Management

Provide supportive care and address secondary issues related to the envenomation as follows:

1. Anticipate the need for aggressive airway management with intubation and prolonged ventilation in all patients presenting with neurotoxic envenomation, particularly those who present late with impending respiratory failure or fail to respond to antivenom.

  • For any neurotoxic snakebite producing a cholinergic crisis, consider atropine 0.5 mg IV/IO titrated by auscultation to dry up bronchial and oral hypersecretions posing a risk to airway or breathing.

Repeat original dose every 5 minutes until resolution of crackles, rales, bronchospasm has been achieved. Pediatric atropine doses should be weight based at a dose of 0.01 mg/kg, up to 0.25 mg.

  • For neurotoxic snakebites in the Middle East, North Africa, and Central Asia without cholinergic crisis, but causing ptosis and respiratory muscle weakness, consider administering trial dose of 0.5 mg atropine followed by 1.0 mg neostigmine IV/IO to temporarily reverse neuromuscular weakness and delay the need for intubation. Pediatric doses should be weight based at a dose of 0.01 mg/kg, up to a maximum of 0.25 mg atropine with 0.5 mg neostigmine.54,74–77

Not all patients will respond, but those who do will show temporary improvement (reversal of ptosis, increased respiratory muscle strength, etc). If no response to neostigmine, do not reattempt. If positive response is achieved, repeat every 1 - 4 hours as needed (maximum dose in 24 hours = 10 mg adults / 5 mg pediatric) until antivenom has definitively reversed the paralysis. 

2. For hemotoxic envenomations, all internal and external active bleeding should cease within 30 – 60 minutes of antivenom administration once the appropriate dose has been given. Packed red blood cell or whole blood transfusion can be considered if the patient is in hemorrhagic shock.17,69,70, 78-82 Platelets, fresh frozen plasma, cryoprecipitate, TXA, and other agents are not effective in these cases due to the mechanism of the venoms.

3. Ketamine and fentanyl are preferable for analgesia. Histamine release from morphine may mask signs of an allergic reaction or worsen hypotension.

4. It is important to keep the limb significantly elevated (> 60º is ideal) whenever possible to limit dependent edema and swelling.

5. DO NOT routinely de-roof or aspirate blisters, bullae, or blebs unless they are causing significant discomfort or uncontrolled rupture appears imminent. If abscess is suspected, treat according to existing protocols for abscess management.

6. DO NOT perform fasciotomy for snakebites. Compartment syndrome is rare in snakebites. Even in cases of confirmed elevated intracompartmental pressure, patients who received antivenom without fasciotomy experienced better outcomes (shorter recovery time and less long term morbidity) than those who received fasciotomy.83–86 Appropriate use of antivenom should resolve the underlying issue that is producing the elevated intracompartmental pressures.

7. DO NOT routinely administer antibiotics unless signs and symptoms of an infection are present. Direct infections are rare from most snakebites when prompt, appropriate treatment is given.54

Ongoing Monitoring & Need for Additional Antivenom

1. Monitor the patient closely for signs of progression in the initial hours of treatment until control of symptoms has been achieved.

Serial assessments for signs and symptoms of the neurotoxic, hemotoxic, and cytotoxic syndromes should be repeated at hours 2, 4, 6, 12, 24 (H2, H4, H6, H12, H24).

2. Within the first 24 hours, antivenom may be given at hours 0, 2, 4, 6, 12, and 24 according to the specific criteria for antivenom treatment listed under Criteria for Initial Antivenom Treatment and Repeat Doses.

  • If the treatment criteria have not been resolved at any of these intervals, give an additional dose of antivenom at hours 2, 4, 6, 12, and 24 until control is achieved. Refer to specific dosage instructions for each product listed by COCOM.
  • If symptoms reappear or persist for more than 24 hours after the first dose of antivenom was given, additional treatment intervals should be discussed with a physician expert.
  • If 10 or more vials of a single antivenom have been given without any indications of improvement, consider changing to 2nd line antivenom if possible as species may not be covered. If any indications of improvement have been observed, continue with the antivenom you are using.

3. If the patient is asymptomatic but coagulopathy persists 24 hours after the first dose of antivenom was given, administer a dose of antivenom and repeat laboratory tests every 24 hours until resolution.

4. Continuous monitoring for effectiveness of antivenom dose must be done. Occasionally, pockets of venom can be trapped in swollen tissue compartments and escape into the bloodstream once circulation has improved. This is called recurrent envenomation and is most common within the first 24 - 48 hours after a severe bite with extensive swelling and blistering.78,87–93

  • Continuous clinical monitoring includes hourly checks of vital signs, urine output, and detailed assessment for new or worsening signs of neurotoxic, hemotoxic, or cytotoxic envenomation.
  • Serial laboratory studies including CBC, CMP, PT/PTT/INR, CK, fibrinogen levels (or WBCT if no advanced testing available) may be repeated every 2 hours while signs of envenomation persist.
  • After signs of clinical resolution, monitoring can decrease to every 6 hours.

5. If indications of recurrent envenomation are detected more than 24 hours after the first dose of antivenom was given, treat as follows:

  • Asymptomatic patient with coagulopathy and no other findings: Administer a dose of antivenom and repeat laboratory tests every 24 hours until resolution.
  • Symptomatic patient with new or worsening pain, swelling, bleeding, neurotoxicity, or other indications of active envenomation: Administer an additional dose of antivenom every 2 hours until acute symptoms have resolved completely.

Discharge Recommendations

1. Patients should be held for at least 24 hours after resolution of all signs and symptoms, and the following steps should be completed prior to discharge:

  • Repeat blood tests before releasing the patient to ensure resolution of coagulopathy.
  • Administer a booster dose of tetanus toxoid if needed.
  • Patients should be instructed to return if any new or worrying signs or symptoms develop.

2. Serum sickness is characterized by flu-like symptoms ± rash that typically develops between 1 - 3 weeks after antivenom administration. It is rare with highly purified modern antivenoms but may occur more frequently with some of the second and third line antivenoms listed in this CPG.94–97

Serum sickness may be uncomfortable but is not dangerous. Management is either symptomatic or with a course of oral steroids.94,95,97–99