hypersensitivity

2. • HYPERSENSITIVITY REACTION IN
DENTAL OFFICE

3. Anaphylactic shock
• Anaphylaxis is a severe, whole-body allergic reaction to a chemical that has become an
allergen. After being exposed to a substance such as bee sting venom, the person's immune
system becomes sensitized to it. On a later exposure to that allergen, an allergic reaction may
occur. This reaction happens quickly after the exposure, is severe, and involves the whole
body.
• Tissues in different parts of the body release histamine and other substances. This causes the
airways to tighten and leads to other symptoms.
• Anaphylaxis can occur in response to any allergen. Common causes include:
• Drug allergies
• Food allergies
• Insect bites/stings
• Anaphylaxis is life-threatening and can occur at any time. Risks include a history of any type
of allergic reaction.

4. Symptoms
• Symptoms develop rapidly, often within seconds or
minutes. They may include the following:
• Abdominal pain or cramping
• Abnormal (high-pitched) breathing sounds
• Anxiety
• Confusion
• Cough
• Diarrhea
• Difficulty breathing
• Difficulty swallowing
• Fainting, light-headedness, dizziness
• Hives, itchiness
• Nasal congestion
• Nausea, vomiting
• Palpitations
• Skin redness
• Slurred speech
• Wheezing

5. Presentation
• There is often (but not always) a history of previous sensitivity to an
allergen, or recent history of exposure to a new drug (e.g. vaccination).
Initially, patients usually develop skin symptoms, including generalised
itching, urticaria and erythema, rhinitis, conjunctivitis and angio-oedema.
Signs that the airway is becoming involved include itching of the palate or
external auditory meatus, dyspnoea, laryngeal oedema (stridor) and
wheezing (bronchospasm). General symptoms include palpitations and
tachycardia (as opposed to bradycardia in simple vasovagal episode at
immunisation time), nausea, vomiting and abdominal pain, feeling faint -
with a sense of impending doom; and, ultimately, collapse and loss of
consciousness.
Airway swelling, stridor, breathing difficulty, wheeze, cyanosis,
hypotension, tachycardia and reduced capillary filling suggest impending
severe reaction.

6. Quick reference anaphylaxis algorithm
• Rapid assessment:
– Airway: look for and relieve airway obstruction; call for help early if there are signs of
obstruction. Remove any traces of allergen remaining (e.g. nut fragments caught in
teeth, with a mouthwash; bee stings without compressing any attached venom sacs).
– Breathing: look for and treat bronchospasm and signs of respiratory distress.
– Circulation: colour, pulse and BP.
– Disability: assess whether responding or unconscious.
– Exposure: assess skin with adequate exposure, but avoid excess heat loss.
• Consider anaphylaxis when there is compatible history of rapid-onset severe allergic-type
reaction with respiratory difficulty and/or hypotension, especially if there are skin changes
present.
• Give high-flow oxygen - using a mask with an oxygen reservoir (greater than 10 litres min-1
to prevent reservoir collapse).
• Lie the patient flat:
– Raise the legs (care, as this may worsen any breathing problems).
– In pregnant patients, use a left lateral tilt of at least 15° (to avoid caval compression).

7. Emergency
• Adrenaline (epinephrine) intramuscularly (IM) in the anterolateral aspect
of the middle third of the thigh (safe, easy, effective):
• Adult IM dose 0.5 mg IM (= 500 micrograms = 0.5 mL of 1:1000)
adrenaline (epinephrine).
• Child IM dose (the equivalent volume of 1:1000 adrenaline (epinephrine)
is shown in brackets):
– >12 years: 500 micrograms IM (0.5 mL), i.e. the same as the adult dose.
300 micrograms (0.3 mL) if the child is small or prepubertal.
– >6-12 years: 300 micrograms IM (0.3 mL).
– <6 years: 150 micrograms IM (0.15 mL).
• Note: half doses of adrenaline (epinephrine) may be safer for patients on
amitriptyline, imipramine, monoamine oxidase inhibitor (MAOI) or beta-
blocker.

8. When skills and equipment are available:
• Establish airway (in anaphylaxis, airway obstruction from tissue swelling is
difficult to overcome and early expert intubation is often needed).
• IV fluid challenge:
– Insert one or more large-bore IV cannulae (enable the highest flow).
– Use intraosseous access (if trained to do so) in children when IV access is
difficult.
– Give a rapid fluid challenge:
• Adults - 500 mL of warmed crystalloid solution (e.g., Hartmann's or 0.9% saline) in
5-10 minutes if the patient is normotensive or one litre if the patient is
hypotensive.
• Use smaller volumes (e.g. 250 mL) for adult patients with known cardiac failure and
use closer monitoring (listen to the chest for crepitations after each bolus).
• The use of invasive monitoring, e.g., central venous pressure (CVP), can help to
assess fluid resuscitation.
• For children - give 20 mL/kg of warmed crystalloid.

9. When skills and equipment are available:
• Chlorphenamine (after initial resuscitation). Dose depends on age:
– >12 years and adults: 10 mg IM or IV slowly.
– >6-12 years: 5 mg IM or IV slowly.
– >6 months-6 years: 2.5 mg IM or IV slowly.
– <6 months: 250 micrograms/kg IM or IV slowly.
• Hydrocortisone (after initial resuscitation). Dose depends on age:
– >12 years and adults: 200 mg IM or IV slowly.
– >6-12 years: 100 mg IM or IV slowly.
– >6 months-6 years: 50 mg IM or IV slowly.
– <6 months: 25 mg IM or IV slowly.
• Monitor:
– Pulse oximetry
– ECG
– BP

10. Antihistamines (after initial resuscitation)
• Antihistamines are a second line treatment for an anaphylactic reaction. The
• evidence to support their use is weak, but there are logical reasons for them.
• 55
•
• Antihistamines (H1-antihistamine) may help counter histamine-mediated vasodilation
• and bronchoconstriction. They may not help in reactions depending in part on other
• mediators but they have the virtue of safety. Used alone, they are unlikely to be lifesaving in
a true anaphylactic reaction. Inject chlorphenamine slowly intravenously
• or intramuscularly.
• The dose of chlorphenamine depends on age:
• >12 years and adults: 10 mg IM or IV slowly
• >6 – 12 years: 5 mg IM or IV slowly
• >6 months – 6 years: 2.5 mg IM or IV slowly
• <6 months: 250 micrograms/kg IM or IV slowly
• There is little evidence to support the routine use of an H2-antihistamine (e.g.,
• ranitidine, cimetidine) for the initial treatment of an anaphylactic reaction.

11. Steroids (give after initial resuscitation)
• Corticosteroids may help prevent or shorten protracted reactions. In asthma, early
• corticosteroid treatment is beneficial in adults and children.
• 57 58
• There is little
• evidence on which to base the optimum dose of hydrocortisone in anaphylaxis. In
• hospital patients with asthma, higher doses of hydrocortisone do not seem to be
• better than smaller doses.
• 59
•
• Inject hydrocortisone slowly intravenously or intramuscularly, taking care to avoid
• inducing further hypotension.
• The dose of hydrocortisone for adults and children depends on age:
• >12 years and adults: 200 mg IM or IV slowly
• >6 – 12 years: 100 mg IM or IV slowly
• >6 months – 6 years: 50 mg IM or IV slowly
• <6 months: 25 mg IM or IV slowly

12. Quincke's edema
• Angioedema or Quinc
ke's edema is the
rapid swelling (edema)
of
the dermis, subcutane
ous tissue,mucosa and
submucosal tissues.

13. Symptoms
• The skin of the face, normally around the mouth, and the
mucosa of the mouth and/or throat, as well as the tongue,
swell up over the period of minutes to several hours.
• The swelling can also occur elsewhere, typically in the hands.
The swelling can be itchy or painful.
• There may also be slightly decreased sensation in the affected
areas due to compression of the nerves.
• Urticaria(hives) may develop simultaneously.
• In severe cases, stridor of the airway occurs, with gasping or
wheezy inspiratory breath sounds and decreasing oxygen
levels.

14. Causative factors
• Drugs like penicillin, aspirin, phenytoin
and others,
• Hereditary angio-oedema is an
autosomal-dominant disorder associated
with recurrent episodes of edema of the
subcutaneous tissue without.
•
• Onset is usually in early childhoodbut may
be delayed even into late adult life.

15. Treatment
• Angioneurotic odema is a medical emergency, it
always better to seek the medical help immediately
• To give airway support in case of medical support
• Antihistamines
• Corticosteroids
• Adrenaline in acute condition
• C1 esterase inhibitors in case of hereditary
angioneurotic edema

16. Erythema multiforme
• Erythema multiforme
(EM) is an acute, self-
limited, and sometimes
recurring skin condition
that is considered to be a
type IV hypersensitivity
reaction associated with
certain infections,
medications, and other
various triggers.

17. Symptoms
• Fever
• General ill feeling
• Itching of the skin
• Joint aches
• Multiple skin lesions:
– Start quickly and may return
– May spread
– May appear as a nodule, papule, or macule and may look like hives
– Central sore surrounded by pale red rings, also called a "target", "iris", or
"bulls-eye"
– May have vesicles and blisters of various sizes (bullae)
– Located on the upper body, legs, arms, palms, hands, or feet
– May involve the face or lips
– Usually even on both sides (symmetrical)

18. Other symptoms that may occur with
this disease:
• Bloodshot eyes
• Dry eyes
• Eye burning, itching,
and discharge
• Eye pain
• Mouth sores
• Vision problems

19. Erythema multiforme

20. History:
• In EM, there may be no prodrome or a mild upper
respiratory tract infection.
• The rash starts abruptly, usually within 3 days. It
starts on the extremities, being symmetrical and
spreading centrally.
• Half of children with the rash have recent herpes
labialis.
• It usually precedes the erythema multiforme by 3 to
14 days but it can sometimes be present at the
onset.

21. Examination:
• The iris or target lesion is the classical feature of the disease.
• Initially there is a dull red flat spot or wheal that enlarges slightly up to 2 cm over 24 to 48
hours.
• In the middle, a small bump, vesicle, or bulla develops, flattens, and then may clear. The
intermediate ring forms and becomes raised, pale, and swollen. The periphery slowly
becomes purple and forms a concentric lesion, resembling a target. Some lesions are atypical
targets with only 2 concentric rings.
• The Koebner phenomenon may occur. This is where a lesion occurs along the line of trauma
and it is typical of psoriasis and lichen planus.
• Lesions appear first on the extensor surfaces of the periphery and extend centrally. The
palms, neck and face are often involved but the soles and flexures of the extremities less
often.
• There may be mucosal involvement in 70% of patients but it tends to be mild and limited to
just one mucosal surface (for example mouth or vulva).
• Oral lesions are most common with lips, palate and gingiva affected. There may be red
conjunctivae and tearing, but eye involvement tends to be mild.
• Genital involvement can produce painful hemorrhagic bullae and erosions.

22. Erythema multiforme
• Investigations:
No specific investigations are
indicated.
• Nikolsky's sign is positive
• A punch biopsy may be required to
confirm diagnosis.
• Management:
In recurrent disease due to HSV,
antiviral therapy is helpful.
• Symptomatic treatment may
include analgesics, mouth wash
and local skin care.
• Steroid creams may be used. If the
mouth is very sore, attention may
have to be given to hydration and
nutrition.
• Lubricating drops for eyes may be
required.

23. Stevens–Johnson syndrome
• Stevens–Johnson syndrome (SJS)
and toxic epidermal necrolysis (TEN) are
two forms of a life-
threatening skin condition, in which cell
death causes the epidermis to separate
from the dermis
• The syndrome is thought to be
a hypersensitivity complex that affects
the skin and the mucous membranes.
Although the majority of cases
are idiopathic (without a known cause),
the main class of known causes is
medication, followed by infections and,
rarely, cancers.

24. Symptoms
• SJS usually begins with fever, sore
throat, and fatigue, which is
misdiagnosed and usually treated
with antibiotics.
• Ulcers and other lesions begin to
appear in the mucous membranes,
almost always in the mouth and
lips but also in the genital and anal
regions.
• Those in the mouth are usually
extremely painful and reduce the
patient's ability to eat or drink.
• Conjunctivitis of the eyes occurs in
about 30% of children who
develop SJS.
• A rash of round lesions about an
inch across arises on the face,
trunk, arms and legs, and soles of
the feet, but usually not the scalp.

25. Stevens-Johnson syndrome

26. Treatment:
• SJS constitutes a dermatological emergency. All medications should be discontinued,
particularly those known to cause SJS reactions. Patients with
documented mycoplasma infections can be treated with oral macrolide or oral doxycycline.
• Initially, treatment is similar to that for patients with thermal burns, and continued care can
only be supportive (e.g. intravenous fluids and nasogastric or parenteral feeding) and
symptomatic (e.g.,analgesic mouth rinse for mouth ulcer).
• Dermatologists and surgeons tend to disagree about whether the skin should be debrided.
• Beyond this kind of supportive care, there is no accepted treatment for SJS. Treatment
with corticosteroids is controversial.
• Early retrospective studies suggested that corticosteroids increased hospital stays and
complication rates. There are no randomized trials of corticosteroids for SJS, and it can be
managed successfully without them.
• Intravenous immunoglobulin (IVIG) treatment has shown some promise in reducing the
length of the reaction and improving symptoms. Other common supportive measures include
the use of topical pain anesthetics and antiseptics, maintaining a warm environment, and
intravenous analgesics. An ophthalmologist should be consulted immediately, as SJS
frequently causes the formation of scar tissue inside the eyelids, leading to corneal
vascularization, impaired vision and a host of other ocular problems.

27. Skin Tests
• Scratch test (also known as a
puncture or prick test). This
test is done by placing a drop of
a solution containing a possible
allergen on the skin, and a
series of scratches or needle
pricks allows the solution to
enter the skin. If the skin
develops a red, raised itchy
area (called a wheal), it usually
means that the person is
allergic to that allergen. This is
called a positive reaction.

28. Intradermal test.
• Intradermal test. After examining
and cleaning the skin, a small
amount of the allergen is injected
just under the skin, similar to
a tuberculosis test.
• During this test, a small amount of
the allergen solution is injected
into the skin.
• An intradermal allergy test may be
done when a substance does not
cause a reaction in the skin prick
test but is still suspected as an
allergen for that person.
• The intradermal test is more
sensitive than the skin prick test
but is more often positive in
people who do not have symptoms
to that allergen (false-positive test
results).

29. Patch test.
• Patch test.
• For a skin patch test,
the allergen solution is
placed on a pad that is
taped to the skin for
24 to 72 hours.
• This test is used to
detect a skin allergy
called contact
dermatitis.

30. Allergy blood tests
• Allergy blood tests look for substances in the blood
called antibodies. Blood tests are not as sensitive as skin tests
but are often used for people who are not able to have skin
tests.
• The most common type of blood test used is the enzyme-
linked immunosorbent assay (ELISA, EIA). It measures the
blood level of a type of antibody (called immunoglobulin E, or
IgE) that the body may make in response to certain allergens.
IgE levels are often higher in people who have allergies
or asthma.
• Other lab testing methods, such as radioallergosorbent testing
(RAST) or an immunoassay capture test (ImmunoCAP, UniCAP,
or Pharmacia CAP), may be used to provide more information.