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1. MSRA > Allergy > Flashcards

Allergy Flashcards

1
Q

How can a diagnosis of seasonal allergic rhinitis be made?

A

based on history and examination alone - further investigations reserved for refractory cases

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2
Q

What are 3 groups allergic rhinitis can be categorised into?

A
  1. season allergic rhinitis (hayfever - tree pollen, grass, mould spores, weeds)
  2. perennial rhinitis - throughout the year (house dust mites, domestic pets)
  3. occupational rhinitis - allergics at work e.g. flour, wood dust, latex
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3
Q

What information can give a clue to the allergic in seasonal rhinitis?

A
  • symptoms timing - tree pollen = spring
  • grass pollen = spring-summer
  • weed pollen = spring- autumn
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4
Q

If the causative agent is not clear in allergic rhinitis, what are 3 tests to consider?

A
  1. skin prick test
  2. blood assays - IgE concentrations via RAST or ELISA
  3. CT - if suspect chronic rhinosinusitis / neoplasia
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5
Q

What are 3 drugs that can suppress the response to skin prick testing?

A
  1. antihistamines
  2. steroids
  3. tricyclic antidepressants
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6
Q

What are 7 ways to diminish exposure to house dust mites?

A
  1. house dust mite impermeable covers for mattresses and pillows
  2. synthetic pillows
  3. acrylic duvets
  4. soft toys off bed
  5. wash bedding once a week high temp
  6. wooden or hard floor coverings (not carpets)
  7. fitted blinds (not curtains)
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7
Q

What are 3 key treatments for allergic rhinitis?

A
  1. topical nasal antihistamines e.g. azelastine - first line for PRN treatment
  2. oral antihistamines e.g. cetirizine, loratadine
  3. topical intranasal steroids e.g. beclomethasone, mometasone - first line for pregnant / breastfeeding patients
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8
Q

What is the management of non-IgE mediated food allergy?

A

Eliminate for 2-6 weeks then gradually re-introduce e.g. egg ladder, dietitian guidance

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9
Q

What type of hypersensitivity reaction is contact dermatitis?

A

type IV reaction

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10
Q

What is the mechanism of type I hypersensitivity reactions?

A
  • anaphylactic
  • antigen reacts with IgE bound to mast cells
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11
Q

What are 2 examples of type I hypersensitivity reactions?

A
  1. anaphylaxis
  2. atopy e.g. asthma, eczema and hayfever
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12
Q

What is the mechanism of type II hypersensitivity reactions?

A

cell bound: IgG or IgM binds to antigen on cell surface

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13
Q

What are 7 examples of type II hypersensitivity reactions?

A
  1. autoimmune haemolytic anaemia
  2. ITP
  3. Goodpasture’s syndrome
  4. Pernicious anaemia
  5. Acute haemolytic transfusion reactions
  6. Rheumatic fever
  7. Pemphigus vulgaris bullous pemphigoid
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14
Q

What is the mechanism of type III hypersensitivity rections?

A

immune complex - free antigen and antibody (IgG, IgA) combine

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15
Q

What are 4 examples of type III hypersensitivity reactions?

A
  1. serum sickness
  2. systemic lupus erythematosus
  3. post-streptococcal glomerulonephritis
  4. extrinsic allergic alveolitis (acute phase)
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16
Q

What is the mechanism of type IV hypersensitivity reactions?

A

T-ell mediated

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17
Q

What are 7 examples of type IV hypersensitivity reactions?

A
  1. allergic contact dermatitis
  2. tuberculosis/ tuberculin skin reaction
  3. graft versus host disease
  4. scabies
  5. extrinsic allergic alveolitis (chronic phase)
  6. multiple sclerosis
  7. Guillain-Barre syndrome
18
Q

What is the mechanism of type V sensitivity reactions?

A

antibodies that recognise and bind to cell surface receptors; either stimulate them or block ligand binding

19
Q

What are 2 examples of type V hypersensitivity reactions?

A
  1. Myasthenia Gravis
  2. Graves’ disease
20
Q

Is IV hydrocortisone indicated in the management of anaphylaxis?

A

no - previously recommended but evidence base poor, now removed in 2021 update

21
Q

What is the adrenaline dose in anaphylaxis children < 6 months?

A

0.1 - 0.15 mg (0.1-0.13ml 1 in 1000)

22
Q

What is the adrenaline dose for anaphylaxis in children 6 months to 6 years?

A

0.15 mg (0.15 ml 1 in 1000)

23
Q

What is the adrenaline dose for anaphylaxis in children age 6 - 12 years?

A

0.3 mg (0.3 ml 1 in 1000)

24
Q

What is the adrenaline dose for anaphylaxis in children >12y and adults?

A

0.5 mg (0.5 ml 1 in 1000)

25
Q

What is the algorithm for anaphylaxis management?

A

IM adrenaline injection; repeat after 5 minutes if necessary
if symptoms persist despite 2 doses - IV fluids, IV adrenaline infusion (seek expert help)

26
Q

What is the dosing for IV adrenaline infusion for refractory anaphylaxis?

A

1mg (1ml of 1mg/ml 1:1000) adrenaline in 100ml of 0.9% sodium chloride
in adults + children: 0.5-1.0 ml/kg/hour initially, then titrate according to clinical response

27
Q

What medication should be given following resolution of anaphylaxis?

A

non-sedating oral antihistamines (in preference to chlorphenamine) - esp if persistngin skin symptoms (urticaria/angioedema)

28
Q

How long do serum tryptase levels remain elevated after anaphylaxis?

A

up to 12h

29
Q

What should happen to all patients with a new diagnosis of anaphylaxis?

A

refer to specialist allergy clinic; give 2 adrenaline injectors as interim measure before assessment (unless drug-induced)

30
Q

What are 4 criteria for a fast-track discharge after anaphylaxis (after 2 hours of symptom resolution)?

A
  1. good response to single dose adrenaline
  2. complete resolution of symptoms
  3. given adrenaline auto-injector + trained how to use it
  4. adequate supervision following discharge
31
Q

What are 2 criteria for discharge after 6 hours following anaphylaxis symptom resolution?

A
  1. 2 doses IM adrenaline needed
  2. previous biphasic reaction
32
Q

What are 5 reasons to discharge minimum 12 hours after anaphylaxis symptom resolution?

A
  1. severe reaction requiring >2 doses of IM adrenaline
  2. patient has severe asthma
  3. possibility of ongoing reaction e.g. slow release medication
  4. patient presents late at night
  5. patient in areas where access to emergency access care may be difficult
33
Q

What is used as a control for skin prick testing?

A

histamine (positive) and sterile water (negative) controls

34
Q

After how long can a skin prick test be interpreted?

A

15 minutes

35
Q

What type of allergens is skin prick testing used for?

A

food allergies + pollen

36
Q

When is radioallergosorbent testing (RAST) used?

A
  • when skin prick tests not suitable e.g. extensive eczema, patient taking antihistamines
  • used for food allergies, inhaled allergens (e.g. pollen) and wasp/bee venom
37
Q

How does RAST testing work?

A
  • determines amount of IgE that reacts specifically with suspected or known allergens e.g. IgE to egg protein
  • results given in grades from 0 (negative) to 6 (strongly positive)
38
Q

What condition is skin patch testing useful for?

A

useful for contact dermatitis, allergens + irritants

39
Q

How many allergens can be tested for with skin patch testing?

A

30-40 minutes

40
Q

How long does it take before skin patch testing can be interpreted?

A

48 hours - removed + read by dermatologist

1. MSRA (27 decks)

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