Anaphylaxis Flashcards
Define anaphylaxis
Acute, severe, generalised or systemic, hypersensitivity reaction that is characterised by rapidly developing life-threatening airway and/or breathing and/or circulation problems
What are the causes of anaphylaxis
In children, 85% due to food allergy (and most are in those <5yo)
Foods (1-3/-1/2) e.g. peanuts
Drugs e.g. penicillin, NSAIDs, anaesthesia, opioids
Insect stings e.g. wasps and bees
Latex
Contrast agents
Can require a co-factor e.g. NSAIDs, alcohol, another food, exercise to provoke anaphylaxis
What are the symptoms of anaphylaxis
Acute onset of symptoms on exposure to allergen (minutes to an hour)
SOB, sensation of choking
Inspiratory stridor (“Wheeze”) and hoarse voice
Swelling of lips and face
Pale, clammy skin
Urticaria, erythema, pruritus
Confusion or disorientation
Nausea, vomiting, diarrhoea, incontinence
Abdominal cramps and pain
Agitation, anxiety, sense of doom
What is a biphasic reaction
A two phase anaphylactic event.
Symptoms/anaphylaxis returns without re-exposure to the allergen.
The second reaction can be less severe, equal to or more severe than the first reaction.
occur 1-72h after the first reaction in up to 20% of patients
What are the signs of anaphylaxis on examination
Obs: tachypnoea, tachycardia, hypotension
General: cyanosis, pallor, clammy, orofacial swelling, rhinitis, conjunctivitis, urticaria, erythema, reduced consciousness
Respiratory: wheeze, inspiratory stridor, hoarse voice, accessory muscle use, hyperinflation
What are the signs of anaphylaxis on A-E assessment
Airway: swelling, hoarseness, stridor
Breathing: high RR, wheeze, cyanosis, SpO2 <92%, confusion
Circulation: pale, clammy, low BP
Disability: drowsy, coma
Skin: urticaria/angioedema
What is hereditary angioedema
C1 esterase deficiency
Leads to recurrent facial swelling and abdominal pain
What investigations should be done for anaphylaxis
CLINICAL DIAGNOSIS → treat immediately
Bedside: ECG
Bloods: ABG, U&Es, mast cell tryptase
Other: CXR
What is the management for anaphylaxis without cardiorespiratory arrest
- A-E assessment + call for help
- Position patient
- Adrenaline IM (anterolateral middle 1/3 thigh)
- Repeat at 5 min intervals according to response
- Establish airway + high flow oxygen
- IV fluids 20ml/kg
- Serial re-assessment (sats, ECG, BP)
Consider chlorphenamine (IM or slow IV), Hydrocortisone (IM/slow IV), nebulised salbutamol for wheeze
What is the management for anaphylaxis with cardiorespiratory arrest
CPR
What are the doses of adrenaline for anaphylaxis
1:1000
<6: 0.15 mg IM
6-12: 0.3 mg IM
>12 0.5 mg IM
What positions should the patient be put in in anaphylaxis
Predominant airway/breathing problems: sit them up
Circulation problems: lie flat ± legs up
Unconscious: recovery position
Pregnant: on their left
Feels faint: Do NOT sit or stand them up
What treatment should be given after an anaphylactic patient is made stable
- Antihistamine e.g. Chlorphenamine
a. <6: 2.5mg IM/IV
b. 6-12: 5mg IM/IV
c. >12: 10mg IV/IM - Corticosteroid i.e. hydrocortisone
a. <6: 50mg IV/IM
b. 6-12: 100mg IM/IV
c. >12: 200mg IV/IM - Monitor for biphasic reaction (6-12 hours)
- Take serum tryptase level if there is uncertainty about anaphylaxis
What is the prognosis for anaphylaxis
Outcome is very dependent: success of therapy, time of diagnosis, co-morbidities, age
Severity of previous reactions does NOT predict the severity of future reactions
Individuals with previous reactions are at higher risk for recurrence
1 in 1,000 are fatal (mostly in adolescents when concerning food)