Australian Doctor 16th February 2024 AD 16th Feb issue | Page 20

16 FEBRUARY 2024

A

B

Figure 3A . Multiple linear lesions from C . fleckeri sting . B . Delayed hypersensitivity reaction to a sting .

Table 1 . Jellyfish types , clinical effects , first aid and treatment for the two major jellyfish clinical syndromes Box 2 . Associated features in Irukandji syndrome

• Wash sting site with sea water and remove tentacles

• Hot water immersion at 45 ° C for 20 minutes *

• Avoid vinegar , which may worsen the pain

Medical management

In patients presenting with severe envenoming following pre-hospital cardiac arrest , treatment should be continued as per advanced life support but may include the addition of IV antivenom .

There is very limited evidence for the effectiveness of box jellyfish antivenom . An animal study demonstrated that administration of antivenom even before envenoming did not prevent cardiovascular collapse , supporting the rapid effects of the venom . 5 There have also been at least four fatalities despite the administration of antivenom . 3 Do not administer IM

• Wash sting site with sea water and remove tentacles

• Apply vinegar

• CPR for unconscious patients

Further intervention is rarely required Hospital transport for :

• Analgesia ( oral and IV )

• Advanced life support for cardiovascular collapse

• Consider box jellyfish antivenom if not responsive to supportive measures

* There is evidence only for bluebottle stings , but it is likely to work with other minor jellyfish stings 2 Adapted from Berling I et al 2015 7

PAGE 18 antivenom because it will not reach the systemic circulation rapidly . Although IV antivenom should be considered in patients with severe envenoming , early and ongoing CPR is far more important .

Irukandji syndrome

Irukandji syndrome occurs mainly in the north of Australia , but there are occasional reports from further south . ‘ Irukandji ’ refers to the clinical syndrome and not the type of jellyfish that causes the effects . Although a number of different jellyfish have been reported to cause Irukandji syndrome , it is classically associated with stings from

• Wash sting site with sea water and remove tentacles

Hospital transport for :

• Analgesia ( oral and IV )

• Cardiac investigations ( ECG , troponin , echocardiogram )

• Cardiac monitoring and , rarely , treatment for pulmonary oedema

C . barnesi . Most stings are due to contact with the bell rather than the tentacles , like most other jellyfish stings . Only one death has been associated with Irukandji syndrome , but the severity of the generalised pain and systemic effects mean that most cases require medical treatment . 6 Studies of C . barnesi demonstrate that the venom causes secondary release of catecholamines , which are likely the cause of the major clinical effects .

CLINICAL EFFECTS Irukandji syndrome is the second major clinical syndrome associated with jellyfish stings ( see table 1 ). It is characterised by delayed onset ( 20-30 minutes later ) of severe generalised pain ( muscle , abdominal , chest and back ) associated with autonomic and cardiac systemic toxicity in a proportion of cases ( see box 2 ). There are minimal local effects and often only mild pain at the sting site ; in some cases , the site of the sting may be difficult to determine .

TREATMENT Most stings require treatment in hospital because of the severity of the pain and systemic effects . The pain almost always requires IV opioid analgesia — either morphine ( 2.5-5mg every 5-10 minutes ) or fentanyl ( 25-50μg every 5-10 minutes ). Large amounts of opioids are often required for the pain . The nausea and vomiting can be treated with antiemetics , and benzodiazepines may be useful for agitation and anxiety . Perform an ECG and troponin in all patients .

The patient can be discharged after six hours if the pain settles and they have a normal ECG and troponin . If there is any evidence of cardiac effects on ECG or troponin , they require admission and may require an echocardiogram . In severe cases , admission to a critical care unit may be required for acute pulmonary oedema or cardiogenic shock . These patients should be managed with oxygen and positive-pressure ventilation , with or without inotropes .

Discussion with the National Poisons Centre Network ( 131 126 ) or a clinical toxicologist is advised in severe envenoming .

Other jellyfish stings

Many other jellyfish species cause stings , but in most cases , the jellyfish is not identified , and the patient is treated based on the history of a marine sting and the clinical effects . The better-known ones in Australian waters include the mauve stinger , the hair jellyfish , the jimble and other box jellyfish .

Most stings result in local pain with linear erythematous eruptions , similar to bluebottle stings ( see table 1 ). Systemic effects are rare , and Irukandji-like stings are uncommon . Hair jellyfish can cause injuries to the eye or cornea , and these should be treated like any other eye injury — with copious irrigation .

Treatment is symptomatic , supportive and similar to treatment for bluebottle stings . First aid includes washing off or removing the