Anaphylaxis

Question 1

Define anaphylaxis

Answer 1

Acute,severe, systemic,life threatening generalized systemic hypersensitivity reaction to an allergen which occurs minutes or few hours after exposure to a provoking agent.
Characterized by rapid & massive degranulation of mast cells & basophils releasing histamine &other mediators

Question 2

Cofactors that increase the likelihood of developing anaphylaxis

Answer 2

Exercise
Concomitant ingestion of alcohol
Inter current infections
Fever
Emotional stress
Travel
Other disruption of routine
Pre menstrual status

Question 3

Types of anaphylaxis

Answer 3

1. Uniphasic
   - most common
   - usually peaks within 30mins to 1hr after Sx onset
   - resolve spontaneously
2. Protracted
   - lasts to hours to days without complete resolution
3. Biphasic
   - recurrence after 01-72 hrs

Question 4

Mx of anaphylaxis

Answer 4

Acute side bed
Ensure airway patency *100% O2 15L in NRBM
Intubate if respi obstruction
Remove triggering allergen
Raise legs to improve circulation

Adrenaline 0.5mg 1:1000 repeat every 05 mins, guide with the vitals
IV chlopheniramine 10mg IV
Hydrocortisone 200mg IV

IV fluids - NS 500ml over 1/4hr up to 2L
Titrate against BP

If wheezing, bronchodilators

Question 5

Adverse effects of Adrenaline

Answer 5

Transient pallor
Tremors
Anxiety
Dizziness
Headache

Ventricular arrhythmia
HTNve crisis
MI
Pulmonary edema

Question 6

Reasons for an apparent lack of response to IM adrenaline

Answer 6

1. Adrenaline injected too late
2. Low/ expired dose
3. Injection site not optimal
4. Error in Dx
5. Short needle
6. Patient taking beta adrenergic blocker which interferes with the adrenaline effect