Allergy specialist Dr Celia Zubrinich offers practical tips for managing anaphylaxis – and some traps to avoid as well…
Two adrenaline auto-injectors are available in Australia: the EpiPen® has been used for decades, and the Anapen® came onto the market in late 2021. Both devices come in doses of 0.15 mg for children and 0.3 mg for adults. The Anapen® also comes in a 0.5 mg dose that is safe for all individuals over 50 kg, in alignment with ASCIA guidelines, Dr Zubrinich says. For context, this is the dose that people would receive by ambulance protocols and by weight-based dosing guidelines from ASCIA if you’re not using an autoinjector.
Studies have shown some people need more than one 0.3 mg dose of intramuscular adrenaline to treat anaphylaxis effectively and the 0.5 mg dose may therefore be more suitable in some cases, particularly “where we know that people have needed a lot of adrenaline resuscitation in the past – and really [for] anyone over 50 kg,” Dr Zubrinich notes.
We have physiologic data showing that 0.5 mg has a greater effect than 0.3mg, but we don’t yet have prospective data to say this dose is mandatory or definitely superior, she adds, so patient habit or preference should also be taken into consideration.
“When anaphylaxis is occurring it is very frightening and people often cannot think very flexibly, so if people have been trained and hardwired how to use a certain device it may be quite appropriate for them to stick with that,” she says.
“If they are very open to change or if they are newly receiving an adrenaline pen, then both options should be carefully considered.”
The devices have other differences that may influence the choice, she adds.
The EpiPen® is slightly shorter but a little thicker than the Anapen and the mode of administration differs. You need to remove both ends of the Anapen, place it on the thigh, and press the red button to activate adrenaline delivery. With the EpiPen, you need to remove one end and press it into the thigh, which activates delivery via a spring-loaded mechanism.
“It can be worth demonstrating this to patients so they can select which one seems more intuitive to them,” Dr Zubrinich says.
Delayed adrenaline administration has repeatedly been shown to result in more severe or fatal anaphylaxis outcomes, so GPs should instruct patients to use their auto-injector if they have any systemic life-threatening features, including “anything to do with the airway or cardiovascular compromise where we think blood pressure is low,” Dr Zubrinich says.
She notes measuring blood pressure may not be an option at the time, but “if the person has that distinctive sensation of the blood pressure dropping – faintness, weakness, dizziness, that primal sense of ‘I need to lie down’ – then adrenaline should be administered.”
Importantly, encourage patients to use their auto-injector if in doubt.
“If they are sort of feeling like ‘oh, I don’t think I should do it … I think maybe I am on the line”, err on the side of caution,” she says. “If it was to be administered, I reassure people nothing bad has been done. You cannot essentially harm yourself with a dose of intramuscular adrenaline.”
PBS authority permits people to carry two devices. Dr Zubrinich advises patients to always have both with them so they are not worried about using their auto-injector “too early and wasting it.”
Patients should know they need to call an ambulance if they’ve used their auto-injector and to explain this when they ring, she adds.
“I emphasise to people when they call for emergency services not to say ‘oh, I’m not sure what was in my taco wrap’ or ‘I don’t know why I reacted’… If you say, ‘I have used my adrenaline pen’ then they know this is anaphylaxis and it is a top priority.”
While the initial authority must come from a specialist such as an allergist, immunologist, respiratory physician or paediatrician, if someone has received adrenaline in hospital, then anyone can prescribe an adrenaline pen with authority, she says.
“So if your patient gets sent home from ED, got adrenaline, did not get an adrenaline pen script and you are in the process of making a referral to an allergist, you can provide them with an authorised EpiPen or Anapen prescription in the meantime.”
You can also ring up and get authority for two more pens if a device is used, lost, broken, or out of date and they have PBS authorisation, she says.
Additionally, while only two pens can be prescribed on any PBS-authorised script, more than one script can be dispensed to a patient on a separate occasion if it is deemed clinically appropriate or necessary.
“There might be circumstances where you think it is appropriate to have more than two pens, for example people going to very remote locations, some children who live between two households, people who’ve had very severe anaphylaxis … and we know they’ve needed a lot of adrenaline resuscitation in the past,” she says.
Paediatric food allergies often resolve spontaneously, so children should be reviewed carefully to relieve any unnecessary burden of allergen avoidance, Dr Zubrinich says.
“That can be done usually every couple of years,” she says. “And it can be informed by what has happened in real life as well.”
Some young people have a lot of reactions, she notes, “and we generally like to see them quite regularly.” Others with established allergens, a good management plan, and a track record of fewer reactions do not necessarily need to be seen routinely.
When children are approaching adulthood, she advises arranging an assessment either with their paediatrician or an adult allergist to transition the responsibility for managing them.
A new adult-onset food allergy or a food allergy that has continued from childhood into adulthood is generally here to stay, she adds.
“Thereafter we do not see them in adulthood routinely unless something changes – they want to get pregnant or they want to travel or have a refresher or they say, ‘you know what, I ate this and nothing happened’.”
She stresses that allergy specialists do more than prescribe adrenaline pens. “We spend a lot of time in allergy clinics un-diagnosing suspected allergens rather than just diagnosing things, so I think that’s really important for individual safety but also their quality of life – especially when we think this is going to be a long-term avoidance approach.”
Importantly, many practices triage referrals, so let them know if your patient has been newly diagnosed and the allergen is unknown or if you been unable to get an adrenaline pen. “Those individuals are certainly prioritised,” Dr Zubrinich says.
This is “absolutely critical,” Dr Zubrinich says, explaining that studies of fatal anaphylaxis describe incidents where people “have been propped up, told to walk out to the car or tried to get in the shower, lost consciousness, and never regained it.”
An exception to this is in late pregnancy, when women should lie on their left side rather than supine to reduce the risk of inferior vena cava compression.
People who are extremely breathless and find it terrifying or very uncomfortable to lie down may sit with legs extended (not on a chair with legs hanging) and importantly, should be instructed not to walk around, she adds.
They can then be monitored in case of rebound symptoms.
Follow these steps if a patient in your clinic experiences anaphylaxis.
Other therapies that can support recovery include:
However, “none of those things should ever be prioritised to the detriment of adrenaline.”
Intramuscular adrenaline can be administered to anyone “without restriction or hesitation,” Dr Zubrinich adds.
Unlike intravenous adrenaline – which is associated with significant toxicity and should only be administered in a highly monitored setting – there are no absolute contraindications to intramuscular adrenaline at normal doses. It is suitable for people with known ischaemic heart disease, lung disease, and women who are pregnant.
Key messages:
Useful resources:
ASCIA’s anaphylaxis action plan was updated last year in line with the best available evidence.
ASCIA also has an Anaphylaxis Travel Plan and checklist for travellers.
Learn more about managing anaphylaxis or listen to the podcast with Dr Zubrinich.
Allergy & Anaphylaxis Australia provides free information and support for patients. Trained health professionals answer calls and respond to queries about everyday management. Visit allergyfacts.org.au to subscribe. Ph 1300 728 000
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