I was lucky enough to be given study leave to attend the Royal Society of Medicine Paediatric Emergency Medicine study day. I learnt a lot from the day, and wrote some notes as we went along. The speakers were all excellent, and any errors in my note taking will be my errors in interpretation, rather than theirs.
Here is a summary of the second talk:
Allergy and Anaphylaxis in children
Dr Nicholas Sargant, PEM Consultant
This was a very good update on anaphylaxis. There’s so much I didn’t even realise I didn’t know! There are lots of numbers, and if I could get a copy of the slides I’d be very happy! It was useful to highlight some of the differences in clinical features in children vs. adults, and why some of the investigations are slightly different.
Anaphylaxis is common, and getting more common. There has been a 7 fold increase in admissions for anaphylaxis, and up to 20% of “medical” presentations are allergy related. There are 20 deaths/year due to anaphylaxis and every child in the UK who has died from anaphylaxis also has asthma.
You are more likely to die from being struck by lightening than you are from having anaphylaxis!
Defining anaphylaxis is difficult. There is AAAI diagnostic criteria, and Brighton collaborative case definition. This makes epidemiological studies very difficult. In a retrospective case note review, 4% of asthma admissions to PICU almost certainly had anaphylaxis rather than asthma. But is it anaphylaxis or is it just a side effect? If you’re not allergic to the big six and have no history of atopy, it is questionable whether you are really having an anaphylactic reaction – it might be an adverse drug reaction instead. The big six are: eggs, milk, tree nuts, wheat, peanuts, soy and fish.
When you ask your history, ask if there are any co-factors and list all foods taken in the last 6 hours.
- NSAIDs, URTI, alcohol
Much to my surprise, you CAN get anaphylaxis if you have two triggers – there is at least one documented and proven anaphylaxis to scampi + exercise! So the history is REALLY important. Exercise induced anaphylaxis is more common in adults than children. There is normally a co-factor like pollen exposure, or pollen.
Children are much more likely to get respiratory symptoms than adults are. If a child presents with urticaria only, anaphylaxis is not your most likely diagnosis. Urticaria is most likely to be viral, then idiopathic, and THEN allergic. If you can’t easily identify the trigger (within the last 90 minutes), it is more likely to be viral/idiopathic.
Egg allergy causes an impressive urticarial rash.
Urticaria multiforme/purple urticaria/acute annular urticaria presents with pruritis, fever + migrating lesions. It is often confused with erythema multiforme but tends to have a more raised edge. It is self limiting for 8-10 days. There is an association with antibiotics which may be because of concurrent viral infections and is unlikely to be because of antibiotics.
Our two favourites cheesy paeds pearls for using adrenaline are:
- If it’s more than skin, epi goes in
- Black to attack, grey away (it’s embarrassing putting it in the wrong way round)
Serum tryptases are an unreliable marker in kids and in food allergy and are not in the guidelines for children. They are recommended if suspected venom or drug reaction.
Remember not to just tell parents to cut out dairy – their children may then develop rickets! They need to be referred to a dietician.
Lieberman P, Camargo CA Jr, Bohlke K, Jick H, Miller RL, Sheikh A, Simons FE. Epidemiology of anaphylaxis: findings of the American College of Allergy, Asthma and Immunology Epidemiology of Anaphylaxis Working Group, Ann Allergy Asthma Immunol 2006, 97(5):596-602.
Umasunthar T, Leonardi-Bee J, Hodes M, Turner PJ, Gore C, Habibi P, Warner JO, Boyle RJ. Incidence of fatal food anaphylaxis in people with food allergy: a systematic review and meta-analysis, Clin Exp Allergy, 2013, 43(12):1333-41.
NICE – anaphylaxis assessment to confirm an anaphylactic episode.