Stung Inside A Stinger Net

Irukandji syndrome

This is a clinical diagnosis, there are no confirmatory laboratory investigations available.

Key features include:

• Recent contact with seawater
• A relatively innocuous initial sting
• A delayed systemic syndrome that progresses over minutes-to-hours, characterized by pain in multiple regions distant to the sting site and other symptoms such as nausea and vomiting, and restlessness. Features of a “catecholamine excess” state, such as tachycardia and hypertension, are common.

Any opioid drug will have an analgesic effect in Irukandji syndrome

However, potential problems with pethidine include:

• stimulation of histamine release
• tachycardia and myocardial depression – additive to the cardiotoxicity in Iriukandji syndrome (? direct from Irukandji venom and ? indirect due to excessive catecholamine release)
• accumulation of the neurotoxic metabolite norpethidine (normeperidine) when high doses are required – seizures may occur
• potential drug interactions – e.g. serotonin syndrome if the patient is on other serotonergic medications.
• anticholinergic-like side-effects – e.g. dry mouth.

Fentanyl is my opioid of choice for Irukandji syndrome for a number of reasons:

• potent
• rapid onset
• can be rapidly titrated
• preserves cardiac stability and blunts stress-related hormonal changes at higher doses
• rarely elicits histamine release
• no toxic metabolites

Some speculation:

• Interestingly, both pethidine and fentanyl appear to have sodium channel blockade effects. This may be relevant because a putative Irukandji toxin from C. barnesi was shown to be a sodium channel activator in animal models. Also Barnes himself felt that the effects of pethidine were somehow “specific” in that less pethidine than he expected was needed to gain (temporary) relief from the excruciating pain (based on his own experience as a self-inflicted victim of Irukandji Syndrome!). Anecdotal experience in Cairns suggests that less opioid analgeisa may be required if promethazine is also given, perhaps because of promethazine’s additive sodium channel blocking effects.

Yes — but only the sting sites!

Vinegar is known to be of benefit for Chironex fleckeri stings – it irreversibly inactivates nematocyst firing. Also vinegar appears to inhibit Carukia barnesi nematocysts in vitro. Based on this knowledge, vinegar application to possible sting sites in Irukandji syndrome is recommended. The vinegar should be poured over the site continuously for 30 seconds.

Handy tips:

• Repeated applications of vinegar are not required – I know of patients still getting “vinegar wraps” applied many hours after a sting! It is not known when it is too late to apply vinegar and, apart from the smell, vinegar doesn’t cause any harm.
• Vinegar should be applied for even a minor sting if it occurred while swimming in sea water where Irukandji syndrome has been reported – sometimes the initial sting is so minor that the victim doesn’t suspect a jellyfish sting.
• Don’t use methylated spirits, methanol or ethanol – they all cause a massive discharge of nematocysts in cubozoans (box jellies)!

Experience from North Queensland, Western Australia, and the Northern Territory all suggest that Irukandji syndrome is usually a self-limiting, but often very distressing, illness. However in a small percentage of cases there is a risk of life-threatening cardiovascular complications. These include uncontrolled hypertension, transient cardiomyopathy, and acute pulmonary edema.

Irukandji syndrome can kill.

Two fatalities – both tourists – were attributed to Irukandji syndrome in 2002. In each case the cause of death was intracranial hemorrhage, and both patients were hypertensive prior to death. One of the deaths was a 58 year-old man on warfarin with an INR of 4.9, but the other was a healthy 44 year-old male. The identification of the jellyfish species responsible for these deaths has been a source of considerable controversy.

Prehospital care

• Apply generous volumes of vinegar to all visible sting sites to inactivate all undischarged nematocysts (sting cells)
• Do not apply a pressure immobilisation bandage (PIB)
• Transport all patients with pain refractory to first‑aid, or systemic symptoms to a medical facility – this is a potentially life‑threatening emergency

Resuscitation, supportive care and monitoring

• Potential early life‑threats that require immediate intervention include:
• – Severe hypertension
• – Pulmonary oedema
• Administer IV fentanyl (0.5-1.0 microgram/kg/dose) repeated every 10 minutes until appropriate analgesia is achieved. Large doses may be required (e.g. 200-300 microgram). Note: If fentanyl is not available, give morphine 0.1 mg/kg IV in titrated doses
• Treat nausea with IV promethazine (25 mg; 0.5 mg/kg in children)
• Control hypertension refractory to opioid analgesia with an intravenous infusion of glyceryl trinitrate (50 mg in 100 mL starting at 6 mL/minute; 1-4 microgram/kg/minute in children) titrated to achieve a systolic blood pressure <160 mmHg
• Manage pain refractory to opioids with IV magnesium (0.2 mmol/kg up to 10 mmol in adults) administered over 5-15 minutes. Seek expert advice.

Investigations (will be required if the patient has pain or hypertension refractory to opioids)

• ECG (arrhythmia, ischemic changes, conduction blocks)
• Chest radiograph (acute pulmonary edema)
• FBC, UEC, troponin, CK
• Echocardiography

Decontamination, enhanced elimination, and antidotes — nil

Disposition

• This patient has severe pain requiring opioid analgesia. She may be discharged when pain-free and well for 6 hours.
• Cardiovascular complications may necessitate admission to HDU/ ICU level care.

The stinger nets are designed to keep out the larger multi-tentacled box jellyfish Chironex fleckeri. Small jellyfish like Carukia barnesi, which can cause Irukandji Syndrome, can penetrate the net.

As a result most cases of Irukandji Syndrome in North Queensland result from stings inside stinger nets that are close to the shore.

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