Marine envenomations

First aid

• PBI
  • Venomous snakes
  • Blue ringed octopus
  • Cone snail
• Vinegar
  • Box jellyfish (PBI may extend envenomation)
  • Irukandji syndrome
• Hot water immersion
  • Stinging fish
  • Stingray
  • Bluebottles
  • Non-tropical jellyfish

Pressure bandage immobilisation (PBI)

• Do not wash the wound
• ASAP apply bandage below bite site continuing upward along bitten limb
• Leave tips of digits uncovered to allow checking of circulation
• Do not remove pants/clothing – bandage around them
• Take note of location of bite/sting
• Go as high up limb as possible
• Apply splint
• If bitten/stung to trunk – firm pressure only

Vinegar

• When to use?
  • Box jellyfish
  • Irukandji
  • Unknown tropical marine animal
• Inhibits unfired nematocysts from injecting more venom
• Has no effect on venom already injected into patient
• Safe to remove adherent tentacles after this step with gloves/forceps/tweezers (if touched before this can discharge)
• May cause bluebottle nematocyts to fire and thus contra-indicated
• Does not relieve pain
• Need to flood stung area for 30 seconds
• If vinegar unavailable, use sea water (not fresh water as may cause nematocyst discharge)
• Apply cold pack for analgesia

Hot water immersion

• When to use?
  • Fish stings
  • Stingray
  • Bluebottle
  • Non-tropical jellyfish
• More effective than cold water
• May deactivate heat-labile venom toxins or modulate pain receptors
• Prevent rubbing of stung area
• Place stung area in hot water (<45 degrees) for up to 20 minutes, remove briefly then repeat if pain persists
• If no vinegar available – Pick off any adherent tentacles and rinse stung area in sea water
• For bluebottles/non-tropical jellyfish use hot shower

Envenomation and antivenom

• Envenomation – Introduction of venom into human or animal to cause clinical effects
• Consider envenomation in unexplained cases of:
  • Paralysis
  • Myolysis
  • Coagulopathy
  • Renal damage
  • Collapse
  • Convulsions
  • Neuroexcitatory signs
  • Pulmonary oedema
  • Ataxia

Antivenom

• Should only be used when there are clear clinical and/or lab indications of systemic envenomation or major local/regional envenomation
• Dose is the same for children and adults
• In most cases, preferable to dilute to 1 in 10 in IV fluid
• For children 1 in 10 dilution in IV fluid should not exceed 10mL/kg
• Immediate hypersensitivity and delayed hypersensitivity (serum sickness) reactions can occur and must be prepared for

Sea snakes

• Timing of PBI removal
  • Patient must be stable with no clinical signs of envenomation
  • IV line in place
  • Full assessment already made
  • Blood test results obtained
  • Antivenom available in clinical area
  • Resuscitation equipment available in clinical area
  • Antivenom commenced if clinically indicated

Sea snakes

• 31 species in northern Australia waters alone
• Usually not aggressive unless threatened
• Storms can carry them south as far as Sydney
• Clinical effects
  • Usually felt with small teeth marks (mostly non-fang teeth)
  • Pain and swelling usually minimal
  • Paralysis and/or myolysis
  • Coagulopathy is not seen
• Sea snake antivenom
  • 1 vial (3-4 vials for severe envenomation)
  • Polyvalent antivenom is of unknown efficacy for sea snakes
  • Tiger snake antivenom could be considered as an alternative if sea snake antivenom is not available (seek expert advice)

Box jellyfish stings

• Chironex fleckeri
• Nematocysts on tentacles inject venom directly into capillaries leading to sudden cardiorespiratory collapse
• Majority of stings are not severe (75%)
• Typically close to shore from Gladstone and Broome north
• >10% of total skin area involvement is potentially lethal
• Immediate, excruciating pain with linear red welts (ladder tentacle marks)
• First aid: ALS, vinegar, pick off tentacles with gloves/forceps
• If no vinegar: Pickoff tentacles, rinse area with seawater
• Cold pack for analgesia

Box jellyfish stings

• Cardiorespiratory decompensation
  • 1-3 vials of diluted antivenom as an IV push with IV MgSO4 10mmol over 5-15 minutes
  • If cardiac arrest, 6 vials of undiluted antivenom as rapid IV push
  • If no response, repeat up to max 6 vials and repeat IV Mg dose before ceasing CPR
• Non-life threatening
  • Ice packs, analgesia, IV MgSO4 10mmol over 15 minutes and/or 1 vial of diluted antivenom
  • If pain persists, repeat MgSO4 dose
  • Take sticky tape sample of nematocyts, cover with wound dressing and manage as for burns
  • Put sample in 4% formaldehyde
• Keep monitored for at least 6 hours post-antivenom

Irukandji syndrome

• Variety of tropical jellyfish species
• Can occur close or far from shore
• Nematocysts on tentacles and body of jellyfish
• Limited case reports of Irukandji syndrome in temperate waters
• Clinical syndrome
  • Catecholamine storm delayed 20-40 minutes
  • Myalgic limb pain, severe back pain, headache, nausea/vomiting, pallor, profuse sweating, erythematous rash, agitation, impending doom, general vasoconstriction, severe hypertension, Takotsubo, arrhythmias

Irukandji syndrome

• Management
  • First aid: ALS, vinegar
  • Opiod analgesia
  • Suggested adjuncts: Midazolam, chlopromazine, promethazine
  • MgSO4
    • Peripheral inhibitor of catecholamine release and effect
    • 0.15mmol/kg IV bolus then 0.1-0.15mmol/kg/hr infusion
    • Titrate up as long as reflexes intact
    • Wean after 4-6 hours if symptoms controlled
    • Calcium must be available in clinical area
  • Control of hypertension (life-saving to prevent ICH)
    • GTN infusion first-line
    • Phentolamine if GTN contraindicated
    • Wean once controlled for 4 hours
  • ECG monitoring is essential

Bluebottle and non-tropical jellyfish

• Key issue is not missing Irukandji or Box Jellyfish sting
• Hot water immersion for up to 20min then repeat in cycles if ongoing symptoms

Stinging fish

• Mostly localised effects with intense local pain
• Responds well to hot water immersion
• Need to search for retained barb
• Regional nerve blocks and parenteral analgesia is sometimes required
• Disinfection and tetanus prophylaxis are crucial
• Prophylactic antibiotics should be avoided
• Stonefish antivenom considered for confirmed stonefish stings with systemic symptoms, intractable pain and/or oedema
• Dosing based on number of puncture wounds
• Observe for 4-6 hours post-antivenom

Stonefish

• Superbly camouflaged flat fish with erectile dorsal spines with venom glands
• From Brisbane north
• Especially around coral reefs, often in shallow waters and stepped on
• Instant and severe pain, oedema, tenderness and blue discolouration around site
• Dizziness, nausea, hypotension, collapse and cyanosis can occur but is exceedingly rare

Stonefish and Lionfish

Stingrays

• Some have venom-enshrouded tail stings
• Mechanical damage is the greater medical concern
• Any wound to chest or abdomen should be treated as a medical emergency as damage to underlying structures can be fatal
• Lacerations to limbs can also be life-threatening
• Found in coastal waters throughout Australia
• Management
  • Hot water immersion
  • Do not remove barbs pre-hospital
  • Clean and debride lacerations prior to closure
  • Consider prophylactic antibiotics for marine organisms and ensure ADT

Blue-ringed octopus

• Found commonly in all Australian waters
• Saliva contains potent neurotoxin and tetrodotoxin
• Rapid flaccid paralysis can occur, however, usually less severe than this with perioral tingling and mild weakness
• Rapid PBI application is key
• No antivenom
• Supportive care may be required up to 1-2 days

Cone snails

• Only a few from tropical waters are known to be hazardous to humans
• Snail fires venom-coated harpoon dart into skin
• Local pain, progressive paralysis and collapse
• PBI application is key
• Supportive care may be required (esp. respiratory)
• No antivenom

Last Updated on October 14, 2020 by Andrew Crofton