1. Anaphylaxis is a severe systemic allergic reaction that is precipitated by the abrupt release of chemical mediators from mast cells and basophils. It requires prior sensitization and can be life-threatening. 2. Diagnosis is based on acute onset of symptoms involving two or more organ systems such as skin, respiratory, gastrointestinal, or cardiovascular systems after exposure to a known or likely allergen. 3. Treatment involves intramuscular epinephrine injection, antihistamines, corticosteroids, oxygen, fluids, and monitoring for anaphylactic shock. Patients are observed for at least 12-24 hours after initial treatment due to risk of rebound reaction.

1. Anaphylaxis
Mohd Rizuan Ali
MBBS, Bsc Med Sc

2. definition

3. Urticaria
• Edematous + pruritic plaque with pale centre & raised borders
• Caused by blood v/s dilatation & oedema at layer of dermis

4. Angioedema
• Well define, non pitting, non
pruritic swelling
• Caused by swelling at deeper layer
of skin
• May cause burning, numbness or
pain

5. Definition
• Severe systemic allergic reaction to an antigen that is precipitated by
abrupt release of chemical mediators
• Prior sensitization is necessary
Anaphylaxis
Anaphylactoid reaction
•Resembles anaphylactic reactions but do not require prior exposure
•Not immunologically mediated
•It’s d/t direct histamine release from mast cells/ macrophages

6. Pathophysiology

7. Diagnosing Anaphylaxis
highly likely when any one of the following three
criteria is fulfilled…
2. Acute onset of an illness (minutes to several
hours) with involvement of
Skin +/mucosal tissue, or both
AND AT LEAST ONE OF THE FOLLOWING
1. Respiratory compromise
2. Reduced blood pressure or associated
symptoms of end-organ dysfunction
OR
2. Two or more of the following that occur rapidly after
exposure to a likely allergen for that patient (minutes to several
hours)
1.Involvement of the skin-mucosal tissue
2.Respiratory compromise
3.Reduced blood pressure or associated symptoms
4.Persistent gastrointestinal symptoms (eg, crampy abdominal
pain, vomiting) OR
3. Reduced blood pressure after exposure to known
allergen for that patient (minutes to several hours)
1.Infants and children: low SBP (age-specific) or < than
30% decrease in systolic blood pressure
2. Adults: SBP < 90 mm Hg or > 30% decrease from that
person’s baseline

10. Clinical presentation
Airway problems:
• Airway swelling, e.G., Throat and
tongue swelling (pharyngeal/laryngeal
oedema)
• Hoarse voice, stridor
• Wheeze
Breathing problems:
• Shortness of breath
• Confusion caused by hypoxia
• Cyanosis – this is usually a late sign
• Respiratory arrest
Circulation problems:
• Pale, clammy
• Tachycardia
• Hypotension, dizziness, collapse
• Cardiac arrest
Gastrointestinal
•Abdominal pain, nausea, vomiting (stringy mucus),
diarrhea, dysphagia
Central nervous system
•uneasiness (in infants and children, sudden behavioral
change, eg. irritability, cessation of play, clinging to
parent); throbbing headache (pre-epinephrine)
•altered mental status, dizziness, confusion, tunnel vision

11. Risk
Factor

13. Management

14. Management

15. Management of anaphylaxis
• First line meds :
•Adrenaline
• 2nd
line meds :
•Antihistamine
•Hydrocort

16. Rx of Urticaria
• Symptomatic treatment
• Can discharge if there is response to treatment
& no angioedema
1. Antihistamine for at least 3 days
1.Chlorpheniramine (Piriton)
2.Diphenydramine (Benadryl)
3.Promethazine (Phenergen)
2. Prednisolone : 40-60mg PO for 5/7 if lesion is
extensive, or recurrent episode

17. Rx of Angioedema
• Usually involved neck & face, foreskin & scrotum, hands & feet
• Rx is symptomatic but must ready for anaphylactic reaction can occur
• Supportive measures :
•VS every 15 minutes, pulse oxymetry, ECG
•Established IV line
•O2 to maintain SPO2 > 94%
•Make sure intubation / cricothyroidectomy always ready
• Medication :
•Adrenaline
•IM 0.3 -0.5mls of 1:1000 in adult > 45kg
•IM 0.01 ml/kg of 1:1000 in children or adult < 45kg
•Antihistamine & Prednisolon as per urticaria
• Admit for observation at least 12-24 hrs due to rebound can occur
after 6-12 hrs of onset & successful treatment.

18. Rx of Anaphylaxis
• High flow mask
• 2 large bore branula, run 2L of NS/HM bolus
• VS, ECG, pulse oxymetry every 5 minutes
• Always ready for intubation / cricothyroidectomy
• Get anest/ENT consultation for difficult airway
• Consider vasopressor (ie Dopa 2-20mcg/kg/m to keep SBP > 90mmhg
• Medication :
•Deep IM injection of adrenaline 0.01mls/kg of 1:1000 (up to 0.5ml)
•If hypotensive, give 0.1mg of 1:10,000 IV over 5 minutes
•Consider for 1-4mcg/m IV infusion

19. Adrenaline
Intramuscular (IM) Adrenaline
• IM route has several benefits:
• There is a greater margin of safety
• It does not require intravenous access
• The IM route is easier to learn
• Epinephrine has a vasodilator effect in skeletal muscle;
• Skeletal muscle is well-vascularized; after intramuscular injection into the vastus lateralis (mid-
anterolateral thigh), absorption is rapid and epinephrine reaches the central circulation rapidly
Location…
• - anterolateral aspect of the middle third of the thigh

20. Hydrocortisone
• Steroids (after initial resuscitation) may help prevent or shorten reactions
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

22. Before discharge
• Advise pt to avoid allergens
• Register pt for allergy card (inform pharmacy for card & medical
record)
• Send pt for further ix regarding allergy
• Ideally keep Epi- pen available at all times (epinephrine injection)

23. Thank you