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Snake bite or suspected snake bite is a rare but dangerous condition. The Emergency Care Clinical Network has updated this statewide guidance on managing snake bite envenomation or suspected snake bite.

This guidance should be read in conjunction with:

Notes for practitioners

Scope

The clinical guidance and pathways only apply to suspected community-acquired snake bites in patients who are not snake handlers. Specific advice regarding bites in snake handlers and from exotic snakes should be obtained from a clinical toxicologist (for example, Poisons Information Centre 13 11 26).

The clinical pathways in this guidance are relevant for both adult and paediatric patients. For snake bite guidance specific to paediatrics see the Royal Children’s Hospital Snake bite clinical practice guidance

Research regarding the optimal management of snake bite in Victoria is ongoing. This guidance is based on best available evidence and expert opinion. The Emergency Care Clinical Network will review new evidence and update this guidance as appropriate.

Pressure bandage with immobilisation (PBI)

A PBI is recommended first aid for a potential snake bite. The preferred bandage is one which is broad (15cm) and elasticised. Self-adherent bandages should be avoided as they have the potential to become increasingly constrictive, particularly if there is any swelling. Bandaging should start at the bite site, then cover the whole limb, and be as firm as if bandaging a sprained ankle. Immobilisation of the limb, as well as the patient in general, is essential.

Victorian endemic snakes

Snakes endemic to Victoria include the tiger, brown, and red-bellied black snakes. Most venomous snake bites in Victoria are from tiger or brown snakes, and both may present with an initial coagulopathy on blood testing. Bites from endemic snakes are managed with either tiger or brown antivenom. Read our guidance on minimum antivenom stockholdings.

Table 1. Victorian endemic snakes, effects of envenomation and usual antivenom

Snake

Coagulopathy

Neurotoxicity

Myotoxicity

Systemic symptoms

Cardiovascular effects

TMA

Antivenom

Brown

VICC

Rare and mild

-

< 50%

Collapse (33%) Cardiac arrest (5%)

10%

Brown

Tiger

VICC

Uncommon

Uncommon

Common

Rare

5%

Tiger

Red-bellied black

Anticoagulant

-

Uncommon

Common

-

-

Tiger

VICC: Venom-induced consumptive coagulopathy - abnormal INR, fibrinogen very low, D-dimer high
Anticoagulant: APTT 1.5-2.5 x normal ± minor elevation INR, D-dimer and fibrinogen usually normal
TMA: thrombotic microangiopathy - fragmented red blood cells on blood film, thrombocytopenia and a rising creatinine

Blood tests

  1. Initial blood tests: coagulation screen (INR, APTT, fibrinogen), FBE and film, CK, UEC, quantitative D-dimer
  2. Serial blood tests in all patients: coagulation screen (INR, APTT, fibrinogen), FBE and film, CK, UEC, quantitative D-dimer


Note: Point-of-care tests are not appropriate for INR and D-dimer as they may give false negative results in patients with venom-induced consumptive coagulopathy (VICC).

Role of snake venom detection kits (SVDK)

The choice of antivenom is based on the clinical syndrome and local geographical patterns of snake distribution. SVDKs can be useful, but in inexperienced hands they can have significant rates of snake misidentification, false positives and false negatives. For this reason, SVDKs should be conducted by a trained hospital pathology service technician. 

As recommended in the pathway a swab of the bite site should be taken and clearly labelled. Subsequent use of a SVDK should be discussed with a clinical toxicologist. SVDK results should not override clinical and geographical data when choosing the appropriate antivenom to administer to patients with clinical or laboratory evidence of envenomation. If unsure, discuss with a clinical toxicologist (for example, Poisons Information Centre 13 11 26).

Given the narrow range of snakes involved and interpretation issues with SVDK, it is reasonable to exclude SVDK analysis from clinical pathways. This is a decision for local health services. If health services decide to use a SVDK, it can be used in the Snake bite envenomation clinical pathway under ‘Early decision making’ > ‘Choice of antivenom’ along with a strong recommendation that the results are discussed with a clinical toxicologist.  

It is strongly recommended that all cases of envenomation are discussed with a clinical toxicologist to guide treatment (including choice of antivenom) and follow-up healthcare after discharge (for example, Poisons Information Centre 13 11 26).

Location of care

All patients with a suspected snake bite should be managed in a facility with access to antivenom, critical care facilities and a 24-hour laboratory for blood tests. If these criteria are not met, inter-hospital transfer may be required, even for asymptomatic patients. Early discussion with a toxicologist will help determine this need.

Patients presenting directly to Ambulance Victoria should be transferred to an emergency department, where possible bypassing urgent care centres. Patients presenting to urgent care centres should have an emergency ambulance transfer arranged at an early stage.

If patients deteriorate or become unstable, admission and transfer to a tertiary level ICU may be necessary. This decision can be made in consultation with a toxicologist and Adult Retrieval Victoria.

Clinical assessment guide

Circumstances, symptoms and examination on their own are not indicators for antivenom. Consider all aspects when assessing for evidence of envenomation.

This table details information to seek when assessing if envenomation has occurred.

Table 2. Assessing for evidence of envenomation

Circumstances

Symptoms

Examination

  • Confirmed or witnessed bite versus suspicion that bite might have occurred
  • Are there multiple bites?
  • When?
  • Where?
  • First aid?
  • Past history?
  • Medications?
  • Allergies?
  • Headache
  • Nausea or vomiting
  • Abdominal pain
  • Blurred or double vision
  • Slurred speech
  • Muscle weakness
  • Respiratory distress
  • Bleeding from the bite site or elsewhere
  • Passing dark or red urine
  • Local pain or swelling at the bite site
  • Pain in lymph nodes draining the bite area
  • Loss of consciousness and/or convulsions
  • Evidence of a bite or multiple bites, swab for venom but do not test (see Role of snake venom detection kits)
  • Evidence of venom movement (such as swollen or tender draining lymph nodes)
  • Neurotoxic paralysis (ptosis, ophthalmoplegia, diplopia, dysarthria, limb weakness, respiratory distress)
  • Coagulopathy (bleeding gums, prolonged bleeding from venepuncture sites or other wounds, including the bite site)
  • Muscle damage (muscle tenderness, pain on movement, weakness, dark or red urine indicating myoglobinuria)

Treat as envenomed if there is:

  • Neurotoxic paralysis (for example, ptosis, ophthalmoplegia, limb weakness, respiratory effects)
  • Coagulopathy (for example, blood not clotting, INR > 1.3, prolonged bleeding from wounds and venepunctures)
  • History of unconsciousness, collapse, convulsions or cardiac arrest.

Go to Snake bite envenomation clinical pathway and seek advice from a clinical toxicologist (for example, Poisons Information Centre 13 11 26).

Possible evidence of envenomation

There are several relative indications for antivenom that require expert interpretation. 

Early discussion with a clinical toxicologist (for example, Poisons Information Centre 13 11 26) is strongly recommended in the following instances to determine if antivenom is required:

  • any patient with significant symptoms (especially headache and vomiting) or any patient who appears systemically unwell
  • any abnormality of INR, APTT, fibrinogen, D-dimer, full blood count (leucocytosis, evidence of thrombotic microangiopathy) or CK > 1,000 IU/L.

The assessment and management of an envenomed patient is complex and requires clinical toxicology input to advise which antivenom(s), if any, and dosage of antivenom(s) to be administered.

Antivenom administration can result in anaphylactic or anaphylactoid reaction.  See Improved management of anaphylaxis for clinical guidance on managing anaphylaxis. including:

Clinical pathways

For patients with a potential snake bite and no evidence of envenomation:

Suspected snake bite clinical pathway (Victoria) 

For patients with a potential snakebite and evidence of envenomation:

Snake bite envenomation clinical pathway (Victoria)

Patient fact sheet

Get in touch

Claire Doherty
Safer Care Victoria
+61 3 9096 7770

Page last updated: 04 Jun 2019

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