3. Old stuff
          3.1. Old pharm stuff (pre 2009)
              3.1.7. Anaesthetics
                  3.1.7.5. Anaphylaxis
 3.1.7.5.2. Anaphylaxis treatment 

Treatment of anaphylaxis

[CEACCP 2004 Vol 4(4) "Anaphylaxis"]

Immediate management

  1. Stop administration of all agents likely to have caused the anaphylaxis
  2. Call for help
  3. Maintain airway, give 100% O2, lie patient flat with leg elevated
  4. Give epinephrine
    * IM dose = 0.5 - 1mg (0.5-1mL of 1:1000)
    * IV dose = 50 - 100mcg (0.5 - 1 mL of 1:10,000) over 1 min in case of CVS collapse
    * Never give undiluted 1:1000 epinephrine IV
  5. Give IVF
    * Adults may require 2 - 4 L

Subsequent management

  1. Give antihistamines
    * Role of H2 antagonist is controversial
  2. Give corticosteroid (100 - 500 mg hydrocortisone slowly IV)
  3. Consider bronchodilator if necessary
  4. Catecholamine infusion
    * CVS instability may last several hours
    * Epinephrine infusion = 0.05 - 0.1 mcg/kg/min = 3 - 6 mcg/kg/hr
    * For 70kg adult, roughly 4 mL of 1:10,000 per hour
  5. Check ABG
  6. Consider bicarbonate 0.5 - 1 mmol/kg
    * 8.4% of NaHCO3 = 1 mmol/mL

Investigation

3 blood samples to be taken:

  1. Immediately after the reaction has been treated
  2. About 1 hour after the reaction
  3. About 6 hours or up to 24 hours after the reaction

These bloods are to be stored at 4C if analysis within 48 hours, otherwise store at -20C

Tryptase

  • Tryptase is found almost exclusively in mast cells
  • Released during anaphylaxis and anaphylactoid reaction
  • Peak after about 1 hour
  • Blood test needs to be taken at about 1 hour after the reaction to confirm the presence of tryptase

Later investigations

  • Full investigation and referal to allergist

For example,

  • Skin prick tests
  • Measurement of specific IgE
    * By radio-allergosorbent test (RAST) or by CAP test (??)

Screening

Screening for anaphylaxis has no value
* History of previous exposure is often not necessary

Management of patient with previous anaphylaxis

  • Avoid causative agent
  • Consider inhalational induction
  • Premedication
    * Hydrocortisone
    * Inhaled beta-agonist
    * H1 and H2-receptor antagonists
  • Preoxygenation
  • Vasopressor immediately available