Transcript Allergic reactions

Allergy: anaphylactic shock, nettle rash,
Quincke’s edema. Toxicallergic
affections of skin and mucosa. Etiology,
pathogenesis. Diagnostics. Clinical
picture. Complications. Principles of
treatment. The role of a doctor-dentist
in early diagnostics and prophylaxis.
Khabarova N.A.
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Allergic reactions are sensitivities to substances called
allergens that come into contact with the skin, nose, eyes,
respiratory tract, and gastrointestinal tract. They can
be breathed into the lungs, swallowed, or injected. Allergic
reactions are common. The immune response that causes an
allergic reaction is similar to the response that causes hay
fever. Most reactions happen soon after contact with an
allergen.
Many allergic reactions are mild, while others can be severe
and life-threatening. They can be confined to a small area of
the body, or they may affect the entire body. The most severe
form is called anaphylaxis or anaphylactic shock.
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Causes
Common allergens include:
Animal dander
Bee stings or stings from other insects
Foods, especially nuts, fish, and shellfish
Insect bites
Medications
Plants
Pollens
Trends in age and sex standardised admission rates for anaphylaxis, angiooedema, food allergy, and urticaria, with rate ratios (RR) and 95% confidence
intervals, England 1990-2001
Control of the immune system by the hypothalamo-pituitary axis
during an antigen attack.
Formation of sensitised lymphocytes, lymphokines and
antibodies. B-lymphocytes are involved in acquired, humoral
immunity, and T-lymphocytes in congenital, cellular immunity.
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Anaphylaxis is a severe, systemic allergic
reaction
multisystem involvement, including the
skin, airway, vascular system, and GI
Severe cases may result in complete
obstruction of the airway, cardiovascular
collapse, and death
Anaphylactoid or pseudoanaphylactic
reactions display a similar clinical
syndrome, but they are not immunemediated. Treatment for the two conditions
is similar
Etiology
Pharmacologic agents
 Antibiotics (especially parenteral penicillins and other ß-lactams),
aspirin and nonsteroidal anti-inflammatory drugs
 intravenous (IV) contrast agents are the most frequent medications
associated with life-threatening anaphylaxis.
Latex
Stinging insects
ants, bees, hornets, wasps, and yellow jackets.
Foods
Peanuts, seafood, and wheat are the foods most frequently associated
with life-threatening anaphylaxis.
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Symptoms
Common symptoms of a mild allergic
reaction include:
Hives (especially over the neck and face)
Itching
Nasal congestion
Rashes
Watery, red eyes
Anaphylactic reaction as it occurs in mast cells and
basophils.
Symptoms
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Symptoms develop quickly, often within seconds or minutes. They may include the following:
Abdominal pain
Abnormal (high-pitched) breathing sounds
Anxiety
Chest discomfort or tightness
Cough
Diarrhea
Difficulty breathing
Difficulty swallowing
Dizziness or light-headedness
Hives, itchiness
Nasal congestion
Nausea or vomiting
Palpitations
Skin redness
Slurred speech
Swelling of the face, eyes, or tongue
Unconsciousness
Wheezing
Signs and tests
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Signs include:
Abnormal heart rhythm (arrhythmia)
Fluid in the lungs (pulmonary edema)
Hives
Low blood pressure
Mental confusion
Rapid pulse
Skin that is blue from lack of oxygen or pale from shock
Swelling (angioedema) in the throat that may be severe enough to block the
airway
Swelling of the eyes or face
Weakness
Wheezing
The health care provider will wait to test for the allergen that caused anaphylaxis
(if the cause is not obvious) until after treatment.
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Treatment
Anaphylaxis is an emergency condition that needs professional medical
attention right away. If necessary, begin rescue breathing and CPR.
If the allergic reaction is from a bee sting, scrape the stinger off the skin.
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Take steps to prevent shock. Have the person lie flat, raise the person's
feet.
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endotracheal intubation or tracheostomy or cricothyrotomy.
The person may receive antihistamines, such as diphenhydramine, and
corticosteroids, such as prednisone, to further reduce symptoms (after
lifesaving measures and epinephrine are given).
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Allergic Angioedema/Urticaria
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Reactions are induced by histamine and
mediated by IgE
IgE mediated hypersensitivity reaction
Reaction with allergen induces the release of
histamine and other mediators
Result: vasodilatation and edema
Allergic Angioedema/Urticaria
Biochemistry:
 Dependent on presence IgE molec sp to
proteins in causative agent
 IgE molec bind to patients mast cells
 Trigger rxn upon re-exposure to antigen
Allergic Angioedema/Urticaria
Allergic Angioedema/Urticaria
Inciting Agents:
 Medications
 Foods
 Latex
 Environmental (includes insect bites)
Allergic Angioedema/Urticaria
Clinical Presentation:
 Highly variable
 Depends on:
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prev sensitization
type of allergen
+/- urticaria
(pruritic)
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Allergic Angioedema/Urticaria
Clinical Presentation:
 Often seen in patients with other allergic
conditions:
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Atopic dermatitis
Allergic rhinitis
Asthma
Feature
Angio-oedema
Urticaria
Tissues involved
Subcutaneous and submucosal surfaces.
Epidermis and dermis.
Organs affected
Skin and mucosa, particularly the eyelids, lips
Skin only
and oropharynx.
Duration
Transitory (between 24-96
Transitory (usually <24 hours).
Pruritus may or may not be
Pruritus is usually present. Pain and
hours).
Symptoms
present. Often accompanied by pain and
tenderness are uncommon.
tenderness.
Physical signs
Erythematous or skin-coloured swellings
Erythematous patches and wheals on the
occurring below the surface of the skin.
surface of the skin.
Urticaria
Urticaria
Physical urticaria
Solar urticaria
Cold urticaria
Physical urticaria
Aquagenic urticaria
Heat urticaria
Physical urticaria
Dermatographic
Cholinergic
Angioedema
Angioedema on tongue
Algorithm for diagnosis of angio-oedema due to C1-inhibitor
deficiency.
Skin Prick Test (SPT)
Allergic Angioedema/Urticaria
Management:
 As always, airway first
 AAE does respond to:
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Steroids
H1 and H2 blockers
subcutaneous epinephrine
antihistamines.