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