Polyvalent Snake Antivenom
Liverpool Hospital Emergency Department
Indications:
- If there is significant doubt re the snake type
- There is high likelihood of mulga / death adder / taipan envenoming
- If more than 2 monovalent antivenoms required based on snake species available
SWSLHD will predominantly be covered by combination of tiger and brown snake antivenom
Formulation: Stock 1
- 3000 Units Tiger snake AV
- 1000 Units Brown snake AV
- 6000 Units Death adder AV
- 12000 Units Taipan AV
- 18000 Units Black snake AV
Dosage and Administration
- One vial of polyvalent antivenom is recommended if
- There is doubt re the snake type
- There is a high likelihood of mulga / death adder or taipan envenoming
- According to ETG the following scenarios
- Suspected death adder envenoming with isolated neurotoxicity
- Suspected taipan envenoming in patients in far northern Australia with VICC, with or without neurotoxicity
- Suspected taipan, death adder or mulga snake bites in snake handlers
- Suspected mulga snake bite based on location and nonspecific effects (e.g. nausea, vomiting, headache, abdominal pain, diarrhoea), with or without anticoagulant coagulopathy.
- 1 vial of polyvalent diluted 1:10 NaCl 0.9% or Hartmanns IV over 15-20 minutes. If at risk of fluid overload or paediatric case dilute in 1:5 ratio
- Can be given as a push dose in cardiac arrest
∙Side Effects
- there are higher rates of anaphylaxis with polyvalent antivenom
- Immune mediated hypersensitivity reactions occur in 25% of cases with urticaria / rash
- Anaphylaxis occurs in 2-3% of patients and manifests as hypotension
- If there is an acute allergic or anaphylactic reaction temporarily stop the infusion and treat accordingly then recommence the infusion at a slower rate.
- IgE mediated reactions occur generally in snake handlers who have had prior venom exposure and anaphylaxis to venom ****DO NOT WITHHOLD ANTIVENOM IN THESE PATIENT***
- Treat hypersensitivity by ceasing the antivenom temporarily
- Administer IM adrenaline if severe (adult 500mcg 1:1000 IM / paediatric 10microgram/kg IM)
- Delayed serum sickness;
- fever, rash, arthralgia and myalgia:
- Moderate to severe serum sickness can be treated with prednisolone
- There is no role for premedication in Australian snake bites
Pit Falls:
- DO NOT WITHHOLD ANTIVENOM in cases of snake handlers who have venom associated anaphylaxis
- One vial of each of tiger snake and brown snake monovalent antivenom covers most unidentified snake bites in SWSLHD including red bellied black snake envenoming
- Recovery can be difficult to assess and is based on reversibility of the venom effects and time for the body to recover post venom neutralisation
- Systemic effects such as VICC are irreversible and venom only prevents this if given early – will take 24- 36 hours to resolve
- Clotting times will only normalise after a few days
- Discuss major bleeding with clinical toxicologist re role of clotting factor replacement and surgical intervention
- Discharge after resolution of symptoms / no evidence of thrombotic microangiopathy and kidney injury / normal INR / decreasing CK
- All antivenom can be given in pregnancy
- Warn re serum sickness when discharging