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ALLERGY foreign body sensation Powered By Docstoc
					          Allergy
    Dr.Surendra Karanam
Consultant Immunology & Allergy
      1st December 2011
          GP VTS talk
•   Allergy basic science
•   Diagnosis of allergy
•   Food allergy
•   Chronic urticaria & Angioedema
•   Drug allergy
•   Insect sting allergy
•   Allergic rhinitis and asthma
•   Anaphylaxis
• Adverse reactions
  – Immunological hypersensitivity-Allergy
  – Non Immunological
    • Pharmacological/Metabolic
    • Idiosyncratic
    • Toxic
Figure 12-2
Figure 9-7
From: kay: New England J of Medicine Vol 344(1). Jan 4, 2001. 30-37
 Allergens(Antigens which elicit
       IgE response) are
• Small
• Highly soluble
• Enzymes are good allergens-active papain(but
  not inactive) stimulate IgE response(der p1-in
  HDM faeces, papain-meat tenderizer, subtilisin-
  bacterial enzyme-biological component of some
  laundry detergents)
• Carried on dry particles
• ?Transmucosal presentation of low dose antigen
  important
Figure 12-2
Figure 9-35
               Summary
• Allergen-IgE antibody response(Type
  1/immediate hypersensitivity)
• Cross linking of IgE receptors on Mast
  cells/basophils-Release of
  mediators(histamine)-allergic reaction
  (Urticaria, angioedema, anaphylaxis)
            Mast cell mediators
• Preformed mediators
  –   Histamine
  –   Heparin
  –   Tryptase
  –   Carboxypeptidase
• Newly synthesized
  –   Prostaglandin D2
  –   Leucotrienes
  –   PAF
  –   Cytokines-IL4,5, TNF α/β
             Mast cell receptors
• Activating receptors
  –   High affinity IgE receptor
  –   IgG receptors
  –   C-kit
  –   Complement receptors
  –   Toll like receptors
  –   Opioid receptors
  –   PAF receptor
• Inhibitory receptors
  – Beta 2 adrenergic receptor
  – TLR 4
              Clinical case
• 36 year old lady
• Recurrent itchy rashes and lip swelling for
  3 months
• No consistent trigger
• Wondered if it is due to food additives
• Has woken up with lip swelling few times
                Diagnosis
• Chronic Idiopathic urticaria and
  angioedema
          Is it really allergy?
• Urticaria, angioedema, anaphylaxis-
  – Due to histamine
    • Can be ingested histamine (Pseudo allergy)
    • Release from mast cells
       – Can be IgE mediated-True allergy, reaction immediate,
         precipitant often clear.
       – Non IgE-Pseudo allergy/Anaphylactoid reactions
           » Precipitants include infections, stress,
             autoimmune(IgG antibody against mast cell IgE
             receptor), drugs (NSAID, ACE, opiates etc)
           » In many precipitant not clear
        Diagnosis of allergy
• History
• Skin test
• Specific IgE (commonly referred to as
  RAST)
• Challenge testing
• Basophil activation tests
           Specific IgE-pitfalls
• Presence of Specific IgE indicates
  sensitization but not necessarily clinical
  reactivity
• False positives common
  – When total IgE is markedly elevated (Atopic
    Eczema patients)
• Specific IgE-grade 3 and above usually
  indicates true allergy
• False negatives
     • Soon after anaphylaxis (delay or repeat after 6 weeks)
Hamilton RG, Franklin Adkinson N Jr
J allergy Clin Immunol. 2004;114(2):213.
    Levels of IgE which predict clinical
      reactivity with 95% certainity
•   Egg-6ku/L
•   Milk-32 ku/L
•   Peanut 15 ku/L
•   Fish-20 ku/l
 Causes of poor IgE specificity
• IgE tests use crude extracts
  – Eg; Peanut contains about 30 proteins, some
    cross react with pollen allergens, IgE to many
    of these not clinically relevant
  – Solution? Tests for relevant components
    (Component resolved diagnosis)-Specific IgE
    to peanut components ARA H 1,2,3,6
    improves specificity
From Phadia® CRD information sheet
                  Food allergy
• Transient             • Persistent
  – Onset in infancy      – Nuts
  – Milk                     • Avoid all nuts
                             • Legumes, peas
  – Egg
     • MMR safe           – Seafood
                             • Avoid all seafood
                             • Need to consider
                               scombrotoxin poisoning
                      Atopic Marathon



                                                     Asthma
  Incidence




                                                     Rhinitis



                                                     Eczema
                                                     Food allergy
              0   1    2    4      8     16   32   64
                           Age (years)


Redrawn from Durham SR & Church MK, Allergy 2nd edition, 2001, Mosby
               Food allergy
• Oral allergy syndrome
  – Symptoms in the oropharynx
  – Fresh fruit & veg and some nuts
    • Well cooked food tolerated (not nuts-avoid
      altogether)
  – Cross reaction with pollen allergens
  – Reactions tend to be mild
                Food allergy
• Co-factors
  – Exercise
  – Aspirin/NSAID
  – Alcohol
• Exercise induced urticaria & anaphylaxis
  – May be food dependent-Any food or Specific
    food
     • most commonly wheat, specific IgE to wheat
       omega 5 gliadin considered specific for WDEIA
                Food allergy
• Treatment
  – Avoidance
  – Epipen
    • Caution in elderly, cardiovascular problems.
    • Young asthmatics-often need this
  – Medic alert
  – Dietician review
  – Immunotherapy-not yet
                  Aeroallergy
• Allergic rhino-conjunctivitis & asthma
  – Dust mite, pets
     • Perennial symptoms
  – Pollen, weeds, moulds
     • Seasonal
• Treatment
  – Avoidance
  – Topical steroids-very effective
  – Immunotherapy for allergic rhinitis (not if-
    persistent or severe asthma)
            Drug allergy
• True IgE mediated reactions less
  common-Pharmacological/idiosyncratic
  reactions seen more often.
• If nature of reaction unclear or
  Immunological reaction suspected-
  Consider Immunology referral.
       Insect sting reactions
• Wasp & Bee
  – Local reactions-Not IgE mediated, specific
    Immunotherapy not indicated
  – If systemic reactions/anaphylaxis
    • Epipen
    • General precautions
    • Immunology referral for Immunotherapy
                Anaphylaxis
•   Acute onset-within minutes
•   Rapidly progressive
•   Life threatening
•   Systemic reaction with
    – Hypotension and or
    – Bronchospasm
                                Deaths
• Data series – 1992 to 1998 UK data
    – 164 anaphylaxis fatalities with data
         • 25 excluded as not anaphylaxis
    – 20.4 deaths pa UK attributed to anaphylaxis
    – Adrenaline is occasionally the cause rather
      than cure
• Context (2004 deaths UK)
    – IHD 92 589
    – Cerebrovascular diseases 52 961
Clinical and Experimental Allergy, 2000, Volume 30, pages 1144-1150
                Anaphylaxis Deaths




Clinical and Experimental Allergy, 2000, Volume 30, pages 1144-1150
      Anaphylaxis/Panic attack
• Upper airway            • Sensation of choking
  angioedema              • Sensation of DIB leads to
• Bronchospasm              hyperventillation-can lead
• Hypotension causes        to bronchospasm
   – Faintness            • Hypocapnia causes
   – Dizziness               – Faintness
   – Altered sensations      – Dizziness
• Palpitations               – Altered sensations
• Sense of impending      • Palpitations
  doom                    • Sense of impending
                            doom
                 Anaphylaxis
• Most untreated severe acute allergic reactions
  have resolved rapidly with no lasting ill effect.
  Richard Pumphrey
• Most fatal reactions would have been fatal
  whatever treatment was given; we can be sure
  of this because many have occurred at induction
  of anaethisia when expert intensive care was
  immediately at hand. Richard Pumphrey
  – Can we really apply this to food/oral/other agents-SK
• Sometimes the treatment is more life threatening
  than the reaction, and can be fatal. Pumphrey
  RSH Clin Exp Allergy, 2000; 30
• Literature on management of anaphylaxis

 is   long on opinion and short on
 evidence. RP
        Anaphylaxis-treatment
•   Adrenaline-IM
•   Antihistamine
•   Steroids
•   IV fluids
         A survey of A&E Doctors
•   5 cases
•   Treatment (adrenaline yes or no)
•   If used what route
•   78 SHO’s surveyed




Postgrad. Med. J. 2002;78;416-418
                                Case 1
• 55 f
• Widespread raised erythematous rash
  immediately after shellfish
• Dyspnoeic, wheeze & hoarse
• Conscious
• P 110, BP 80/60 RR 28 SaO2 90% on O2


Postgrad. Med. J. 2002;78;416-418
                                Case 1
• Diagnosis
    – ANAPHYLAXIS
• Adrenaline used by 78 (100%)
    – im 35
    – iv 33
    – sc 6



Postgrad. Med. J. 2002;78;416-418
                                Case 2
• 32 m
• Dyspnoea 15 minutes after 2 packets of
  peanuts
• No rash
• Difficulty talking – throat swollen
• Stridor – no wheeze
• P 90, BP 145/78, RR 24, O2 98% air

Postgrad. Med. J. 2002;78;416-418
                                Case 2
• Diagnosis
    – Inhaled foreign body
• Adrenaline used by 44 (56%)
    – im 23
    – iv 13
    – sc 3



Postgrad. Med. J. 2002;78;416-418
                                Case 3
• 30 m
• Widespread pruritic raised erythematous
  rash developed over 45 min
• Carries Epipen – has already used (GP
  prescribed)
• No wheeze
• P 110, BP 158/96, RR 18, SaO2 100% air

Postgrad. Med. J. 2002;78;416-418
                                Case 3
• Diagnosis
    – Urticaria
• Adrenaline used by 8 (10%)
    – im 3
    – iv 1
    – sc 2



Postgrad. Med. J. 2002;78;416-418
                                Case 4
• 26 f
• Widespread pruritic erythematous rash 1
  day after starting penicillin (URTI)
• Asthma and previous rash with antibiotics
  (?which)
• P 104, BP 97/55, RR 16, SaO2 98% air,
  PEFR 80% predicted

Postgrad. Med. J. 2002;78;416-418
                                Case 4
• Diagnosis
    – Rash (?antibiotic related) mild exacerbation
      asthma
• Adrenaline used by 17 (22%)
    – im 6
    – iv 5
    – sc 2


Postgrad. Med. J. 2002;78;416-418
                                Case 5
•   74 m
•   Swollen lower lip and tongue over 45 mins
•   IHD and raised BP
•   Difficulty talking because of tongue
•   No stridor or wheeze
•   P 84, BP 168/95, RR 18, SaO2 97% air


Postgrad. Med. J. 2002;78;416-418
                                Case 5
• Diagnosis
    – Angioedema
• Adrenaline used by 32 (41%)
    – im 17
    – iv 7
    – sc 5



Postgrad. Med. J. 2002;78;416-418
     Diagnosis of Anaphylaxis
• History
• Mast cell tryptase
  – Serum sample
  – Stable at room temperature
  – Collect 1-2 hrs after episode
• Normal mast cell tryptase does not
  exclude anaphylaxis
MAST cell tryptase
     Delayed hypersensitivity
• Cosmetics, jewellery, latex
• Persistent rash-Hands, face
  – Consider Dermatology referral for patch tests
• Eczema
  – In adults not due to food allergy
              Angioedema
• With urticaria
  – Allergy/peudo allergy
• No urticaria, only angioedema
  – Consider Hereditary angioedema and
    acquired angioedema due to C1 inhibitor def
  – If on ACE inhibitor-these must be stopped.
         Lactose Intolerance
• Due to lactase def
• Symptoms; Bloating, diarrhoea, abd pain
• Diagnosis; Hydrogen breath test-Through
  gastroenterology
• Lactose does not cause IgE mediated allergy
• Lactose in medication should not be a problem
  even in patients with complete lactase def (In
  one study patients tolerated 240ml milk)
Thank you

				
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