Download Anaphylaxis

Definitions
 Anaphylaxis :
is a severe, lifethreatening, generalised or systemic
hypersensitivity reaction . Anaphylaxis is
mediated by immunoglobulin E (IgE).
 Anaphylactoid reaction : is
clinically
indistinguishable
from
anaphylaxis, but are mediated by the drug
or substance directly, and not by
sensitised IgE antibodies.
Foods




Cow’s milk
egg whites
fish
nuts (peanuts, Brazil nuts, almonds, hazelnuts,
pistachios, pine nuts, cashews, sesame seeds,
cottonseeds, sunflower seeds, millet seeds)
 shellfish
 Others : Bananas, beets, buckwheat, Chamomile tea,
citrus fruits, kiwis, mustard, pinto beans, potatoes,
rice, and seeds
Venoms and
saliva
 Hymenoptera (bees, wasps, yellow jackets, sawflies)
 Others : jellyfish, kissing bug (Triatoma), Deer flies,
fire ants, rattlesnakes
Drugs
Antibiotics
 Penicillins
 Others
:
Amphotericin
B
,
cephalosporins,
chloramphenicol , ciprofloxacin , nitrofurantoin ,
streptomycin, tetracycline, vancomycin
Aspirin and nonsteroidal anti-inflammatory drugs
Miscellaneous other medications
 Opiates , succinylcholine, thiopental
 Allergy extracts, antilymphocyte and antithymocyte
globulins, antitoxins, carboplatin , corticotropin , dextran,
folic acid, insulin, iron dextran, mannitol , methotrexate,
methylprednisolone, parathormone, progesterone ,
protamine sulfate, streptokinase ,, trypsin, chymotrypsin,
vaccines
Latex rubber
Radiographic contrast media
Blood products
 Cryoprecipitate , immune globulin, plasma, whole
blood
Physical factors
 Cold temperatures, exercise
Idiopathic
Antigen enters body
Mast cells become
sensitized
Antigen reenters
body
Antibodies produced
Attach to surface of
mast or basophil
cells
Attaches to
antibodies on mast or
basophil cells
Mast cell degranulates, releases
Histamine ;Leukotrienes ; Slow reacting substance of
anaphylaxis (SRS-A) ; and Eosinophil chemotactic
factor (ECF)
Action of histamin
 Smooth muscle contraction
 Increased vascular permeability
 Inhibition of central, peripheral nervous system
neurotransmitter release
 Gastric acid secretion
Action of Leukotrienes
 Potent bronchoconstrictors
  vascular permeability & possibly coronary
vasoconstriction
The results are:
 Vasodilation
 Increased Capillary Permeability
 Smooth Muscle Spasm
Cardiovascular
Circulation problems can be caused by:
 direct myocardial depression
 vasodilation and capillary leak
 loss of fluid from the circulation
Cardiovascular manifestations include:
 Hypotension and cardiovascular collapse
 Tachycardia
 Arrhythmias
 ECG may show ischaemic changes
 Cardiac arrest
 Bradycardia is usually a late feature, often preceding
cardiac arrest
Respiratory System
Airway problems:
 Oedema of the glottis tongue and airway structures.
The patient has difficulty in breathing and swallowing
and feels that the throat is closing up
 Hoarse voice
 Stridor and airway obstruction
Breathing problems:
 Dyspnea and tachypnea
 Bronchospasm (Wheeze)
 Confusion caused by hypoxia
 Cyanosis , this is usually a late sign
 Respiratory arrest
Cutaneous
 They are often the first feature and present in
over 80% of anaphylactic reactions
 Flushing
 Erythema
 Urticaria , they are usually itchy
 Angioedema ,most commonly in the eyelids
and lips, and sometimes in the mouth and
throat
 Pruritus without rash
Gastrointestinal
 abdominal pain
 diarrhoea or vomiting.
Haematological
 Coagulopathy
Neurological
 Dizziness
 syncope
 Seizure
Diagnosis
Anaphylaxis is likely when all of
the following 3 criteria are met
Sudden
onset
and
rapid
progression of symptoms
Life-threatening Airway and/or
Breathing and/or Circulation
problems
Skin and/or mucosal changes
(flushing, urticaria, angioedema)
The following supports the
diagnosis
 Exposure to a known allergen for the patient
Remember
 Skin or mucosal changes alone are not a sign of an
anaphylactic reaction
 Skin and mucosal changes can be subtle or absent
in up to 20% of reactions (some patients can have
only a decrease in blood pressure.
 There can also be gastrointestinal symptoms (e.g.
vomiting, abdominal pain, incontinence)
Differential
Diagnosis for
Anaphylaxis
Hypotension
Septic shock
Vasovagal reaction
Cardiogenic shock
Hypovolemic shock
Respiratory distress with
wheezing or stridor
Airway foreign body
Asthma and chronic obstructive
pulmonary disease exacerbation
Vocal
chord
dysfunction
syndrome
Postprandial collapse
Airway foreign body
Monosodium
glutamate
ingestion
Sulfite ingestion
Scombroid fish poisoning
Flush syndrome
Carcinoid
Postmenopausal hot flushes
Red
man
(vancomycin)
syndrome
Miscellaneous
Panic attacks
Systemic mastocytosis
Hereditary angioedema
Leukemia with excess histamine
production
Treatment
of
Anaphylaxis
Immediate Treatment
Removing the trigger for an anaphylactic
reaction if possible and call for help
 Follow the ABCDE of resuscitation
 Adrenaline is the most useful drug for
treating anaphylaxis as it is effective in
bronchospasm and cardiovascular collapse
 If anaphylaxis is caused by an injection,
administer aqueous epinephrine, 0.15 to 0.3
mL, into injection site to inhibit further
absorption of the injected substance
 Place patient in recumbent position and
elevate lower extremities
 Monitor vital signs

Airway and Adrenaline
 Maintain
airway and administer 100%
oxygen
 Adrenaline: If i/v access available give
1:10,000 adrenaline in 0.5-1ml increments,
repeated as required. Alternatively give i/m
0.5 – 1 mg (0.5 – 1 ml of 1: 1000 solution)
repeated each 10 – 15 minutes as required
 for children: 0.01 mL per kg, up to a
maximum dose of 0.2 to 0.5 mL by SC or IM
route and, if necessary, repeat every 15
minutes
Breathing
 Ensure adequate breathing
 Intubation and ventilation may be
required
 Adrenaline will treat bronchospasm
and swelling of the upper airway
 Nebulised bronchodilators (e.g. 5mg
salbutamol) or i/v aminophylline
(loading dose of 5mg/kg followed by
0.5mg/kg/hour). may be required if
bronchospasm is refractory
Circulation
 Adrenaline is the most effective treatment
for severe hypotension
 Insert 1 or 2 large bore i/v cannulae and
rapidly infuse normal saline
 Colloid may be used (unless it is thought to
be the source of the reaction)
 Venous return may be aided by lifting the
patient’s legs or tilting the patient head
down
 If still hypotention consider use of a
vasopressor such as dopamine
Further Management
 Administer the antihistamine : H1 blocker
diphenhydramine (adults: 25 to 50 mg;
children: 1 to 2 mg per kg), usually given
parenterally. and H2 blockers eg. ranitidine
(50mg i/v slowly) or cimetidine (200mg i/v
slowly)
 Corticosteroids : Give hydrocortisone 200mg
i/v followed by 100-200mg 4 to 6 hourly
 Steroids will take several hours to work
Adrenaline IV bolus dose – adult
 Titrate IV adrenaline using 50 microgram
boluses according to response
 If repeated adrenaline doses are needed, start
an IV adrenaline infusion
 The pre-filled 10 mL syringe of 1:10,000
adrenaline contains 100 micrograms/mL
 A dose of 50 micrograms is 0.5 mL, which is the
smallest dose that can be given accurately
 Do not give the undiluted 1:1000 adrenaline
concentration IV
Adrenaline IV bolus dose – children
 IM adrenaline is the preferred route for children
having an anaphylactic reaction
 The IV route is recommended only in specialist
paediatric settings by those familiar with its use (e.g.,
paediatric anaesthetists, paediatric emergency
physicians, paediatric intensivists) and if the patient
is monitored and IV access is already available
 There is no evidence on which to base a dose
recommendation – the dose is titrated according to
response
 A child may respond to a dose as small as 1
microgram/kg. This requires very careful dilution
and checking to prevent dose errors.