Anaphylaxis and it’s Treatment

  • The term anaphylaxis is used clinically to describe a medical emergency caused by allergy to a variety of agents such as drugs ,foods ,plants, chemicals and insects bites
  • It is mediated by IgE
  • Histamine is the most important mediator involved in it.
  • The clinical features are due to laryngeal oedema, bronchospasm and hypertension (anaphylactic shock)
  • An anaphylactic reaction may produce either slowly or rapidly.

Treatment of anaphylactic shock:

Anaphylactic shock needs immediate treatment for laryngeal oedema , bronchospasm and hypotension:

  1. Lay the patient flat and raise his legs
  2. When possible, apply a tourniquet to obstruct the draining blood flow from the site of deposition of the antigen or inciting medication
  3. Attend the airway
  4. Administer adrenaline:
  • Adrenaline 1:1000 solution intramuscularly produces a dramatic reversal of the hypotension, bronchospasm and laryngeal oedema and is life-saving
  • If necessary,it may be repeated cautiously after 15-20 minutes
  • When the patient is severely ill and there is doubt about adequacy of circulation and absorption from I.m. site adrenaline may be injected intravenously, slowly in the dose of 500 mcg ,at the rate of 100 mcg/min
  • The solution should be 1:10,000 but never 1:1000 in intravenous administrations
  • Because 1:1000 administration induce lethal cardiac arrhythmias like fibrillations

Note: patients on a non-selective beta blocker, severe anaphylaxis may not respond to adrenaline and may need additional i.v. salbutamol

  1. Hypotension associated Anaphylactic shock should be corrected by immediate i.v. administration of large quantities of fluids
  2. Glucocorticoids
  • They are routinely administered in the treatment of Anaphylactic shock,as they inhibit late phase of an allergic reaction.
  • They do not inhibit early phase of anaphylactic reactions
  1. Antihistaminic drugs:
  • They do not encounter hypotension and bronchospasm characteristic of anaphylactic shock due to involvement of mediators other than histamine
  • They may prevent late manifestations of allergy,it must be given after adrenaline
  1. Bronchodilators like aminophylline iv or nebulised salbutamol may be needed in patients with resistant bronchospasm
  2. Supportive measures like oxygen and assisted ventilation should be given

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