Clinical Practice Guidelines

Envenomation and Bites

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    Snakebite (Victoria Only)

    Background

    Major venomous snakes in Victoria:

    • Tiger
    • Brown
    • Copperhead
    • Red-bellied Black

    Snake collectors (or their children) may be bitten by exotic or non-Victorian snakes

    Effects

    • Fang marks (may be atypical or invisible) (bite site may be painful, but usually is not)
    • Headache / nausea / vomiting / abdominal pain
    • Tender lymphadenopathy (sometimes)
    • Muscle paralysis (ptosis, blurred vision, facial / bulbar weakness, generalised weakness, respiratory paralysis)
    • Coagulopathy (may only show on laboratory testing or may cause overt bleeding)
    • Hypotension
    • Rhabdomyolysis / renal failure

    Management

    Pre- hospital

    • apply a firm pressure bandage, immobilise joints either side of bite, lay the patient down
    • do not remove bandage until in a centre with full treatment facilities In a major hospital

    In a major hospital

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    Venom Detection Kit (VDK)

    • This "bedside" test is used only to identify the snake and choose appropriate antivenom.
    • It is not used to determine whether antivenom should be given
    • The test takes 20-30 minutes
    • Test a swab from bite site first, if no obvious bite site or test is negative then test urine.
    • Follow the instructions in the kit carefully.
    • Treat very sick patients with both Brown and Tiger snake antivenom while awaiting VDK results.
    • Treat symptomatic patients with both Brown and Tiger snake antivenom if the VDK results are inconclusive or unavailable.

    Antivenom details

    • Only give antivenom to patients with significant systemic features of envenomation or coagulopathy
    • Don't give antivenom to patients who only have lymphadenopathy, minor headache / nausea / vomiting / abdominal pain, or minor disturbance of coagulation (discuss with ICU consultant)
    • Premedicate before giving antivenom (see below)
    • Once VDK result available
    • Use Brown snake antivenom for Brown snake bite (initial dose is 1 ampoule)
    • Use Tiger snake antivenom for Tiger or Copperhead or Red-bellied black snake bite.
    • Initial dose is one ampoule (if using both, then give one ampoule of each)
    • Dilute 1 in 10 with saline and give IV over 30 mins
    • Doses should be repeated if patient remains symptomatic, or if coagulopathy persists, 30 minutes after dose (multiple doses may be needed)

    Premedication

    To reduce the risk of anaphylactic reaction, premedicate once before first dose.

    • Adrenaline 0.01 ml/kg of 1 in 1000 subcutaneously (=10mcg/kg) (Never IV or IM)
    • May also and steroids (to reduce small risk of late reactions) - discuss with consultant
    • Be prepared to treat anaphylaxis (adrenaline +/- O2, IV fluid etc))

    Other treatment.

    Other supportive treatment as indicated (eg ventilation, circulatory support, renal support)

    FFP and platelets may be needed for coagulopathy but will not help unless sufficient antivenom is also given

    Tetanus prophylaxis as indicated by immunisation status.

    Remember:

    • Consider all snake bites as potentially venomous 
    • Leave the bandage on until the patient is stable and in a major hospital with sufficient antivenom available. Apply a bandage if patient is sick. 
    • Never rely on witness's or your identification of the snake - use the Venom Detection Kit 
    • Only give antivenom to patients with weakness, hypoventilation, bleeding or coagulopathy alone 
    • Premedicate prior to antivenom 
    • Repeated doses of antivenom may be needed.

    (Advice on the management of envenomation is available 24 hours a day from the Australian Venom Research Unit on 03 8344 7753)

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    Insect Stings & Bites

    Presentation

    • Minor local reaction with a painful pruritic lesion at the site of the sting
    • More significant local reactions with swelling and erythema > 5 cm diameter
    • Anaphylaxis with laryngeal oedema, bronchospasm & hypotension

    Treatment

    Local reactions

    Local ice application, elevation, analgesics & antihistamines.
    Splint / sling (if upper limb) if severe.

    Systemic reactions

    • Adrenaline 0.01 ml/kg of 1 in 1,000 sol. s.c.; repeat if response incomplete.
    • See ANAPHYLAXIS guidelines if necessary.

    Removal of the sting

    • Bee: Scrape off skin eg. with fingernail (don't squeeze).
    • Tick: Lever out intact, gently, with fine tweezers or blunt forceps under head (magnification helps eg. colposcope). It is important to completely remove the tick and to thoroughly look for others.

    Notes

    Immunotherapy: Purified venom extract is used for desensitisation in individuals with a history of life-threatening anaphylactic reactions. Consult a paediatric immunologist or allergist if considering this procedure. They may use skin testing and RAST tests to confirm the presence of IgE antibodies.

    Parent Information Sheet (Print version - PDF)

    Parent Information Sheet (HTML version)

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    Spider Bites (Victoria Only)

    Red Back Spider

    Found all over Australia. Female has characteristic red / orange stripe on back. Male is very small, usually has no stripe, and is harmless.

    Features of Bite:

    • Local
      • Pain (often becomes intense)
      • Erythema
      • Oedema
      • Sweating
    • General (gradual onset over hours or days)
      • Headache
      • Nausea
      • Vomiting
      • Abdominal pain
      • Tachycardia / hypertension
      • Muscle weakness

    Treatment

    Pressure-immobilisation treatment should not be used. The venom only spreads slowly and confining it to the tissues can increase local pain and tissue damage.

    Pain is often the main treatment issue. Application of cold water can help. Analgesia will be required.

    Antivenom:

    Significant envenomation requiring antivenom treatment is usually indicated by marked local pain and the onset of more generalised features within 2 to 4 hours.

    Following premedication with Adrenaline 0.005 ml/kg of 1 in 1000 subcutaneously (=5mcg/kg), I ampoule of red back spider antivenom is given intramuscularly. The dose is repeated after 2 hours if generalised signs of envenomation remain. The antivenom may be administered intravenously after 1:10 dilution for severe muscle weakness or if there is no response to 1-2 intramuscular doses of red back spider antivenom.

    After administration of antivenom - patients should be observed for at least one hour for symptom recurrence.

    Some other species of spider (including the brown house spider) can produce a similar syndrome. Red back spider antivenom may have arole in treatment, but as yet this is uncertain.

    Funnel Web Spider

    Venomous Funnel Web spiders are confined to the Sydney / Newcastle region of NSW. Small Funnel Web spiders are found in Victoria but their bite is not known to be dangerous.

    Other Spider Bites & Necrotising Arachnidism

    Many other species of spider can bite humans. They usually only result in local irritation / inflammation. Symptomatic treatment includes analgesia +/- antihistamine (for itch). Prophylactic antibiotics should not be given.

    A syndrome of painful local tissue damage varying from small ulcers to extensive necrosis has been described and termed Necrotising Arachnidism. It has been assumed that spider bite is the cause and the common white-tailed spider has been often quoted as the cause - recent evidence suggests this is untrue, and that white-tailed spider bites may be quite painful and itchy but they cause only minor tissue inflammation and no necrosis.

    There is no specific treatment for this condition. Use analgesia and appropriate wound care (which may even require plastic surgery). Prophylactic antibiotics should not be given.

    For all cases of spider bite: consider tetanus immunity status as for any other penetrating wound.

    (Advice on the management of envenomation is available 24 hours a day from the Australian Venom Research Unit on 03 9344 7753)

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    Marine Animal Bites & Stings (Victoria Only)

    Jellyfish

    • Dangerous jellyfish do not occur in Victorian waters.
    • Jellyfish stings can be painful and irritating. Analgesia and antihistamines may be needed.

    Blue-Ringed Octopus

    • Bites are rare and usually only occur when children carry and handle these small shy creatures.
    • Systemic features, including muscle paralysis, may occur rapidly.
    • The pressure-immobilisation technique may slow spread of the venom and should be applied. There is no specific antivenom. Admit the patient to an ICU, mechanical ventilation may be needed.

    (Advice on the management of envenomation is available 24 hours a day from the Australian Venom Research Unit on 03 9344 7753)