ANAPHYLAXIS
Dr. Rami M. Adil Al HayaliALLERGIC DISEASES
Group of diseases that involve an IgE mediated mechanism of hypersensitivity (Type or immediate hypersensitivity reaction )PATHOGENESIS OF ALLERGIC DISEASES
Antigens bind membrane-bound IgE on mast cells Mast cell degranulation Release of vasoactive and inflammatory mediators Vasodilatation, smooth muscle contraction, mucus hypersecretionALLERGIC DISEASES
Atopy: Excessive tendency to form IgE antibodies to otherwise harmless environmental substances. Allergic disease: the clinical manifestation of this inappropriate IgE response, resulting from the release of mast cell mediators (degranulation) Anaphylaxis: systemic allergic reaction due to widespread mast cell degranulationALLERGIC DISEASES
Allergic rhinitis Allergic conjunctivitis Atopic eczema Asthma Urticaria Angioedema Food poisoning AnaphylaxisANAPHYLAXIS
Life threatening multisystemic clinical syndrome Generalized release of mediators from mast cells and basophiles IgE dependant (anaphylactic) and IgE independent (anaphylactoid)ANAPHYLAXIS
Generalized release of mediators results in: 1- Generalized vasodilatation 2- Increase vascular permeability 3- Smooth muscle contraction (bronchospasm and intestinal colic)ANAPHYLAXIS
Commonly responsible antigens: Drugs : penicillin, cephalosporins Insect venom : bees, wasps Foods :peanuts, eggs, banana Latex : medical gloves powder Anaphylactoid reaction: aspirin, radiocontrast media, exercise 20 % unknown aetiologyCLINICAL FEATURES OF ANAPHYLAXIS
Anaphylaxis develops rapidly, usually reaching peak severity within 5-30 min. Early symptoms include a sensation of warmth and itching especially in the palms and soles, axilla and groin, and a feeling of anxiety and panic. These may progress into rash, oedema of the face and neck, and breathlessness Collapse and loss of consciousness may followCLINICAL FEATURES OF ANAPHYLAXIS
Signs on Examination:Breathlessness with wheezing (due to bronchospasm) or strider (due to laryngeal oedema)Flushing and sweatingTachypnoea, tachycardia, and hypotension“ Shock” in 30% of cases (anaphylactic shock)Skin rash ( urticaria and angioedema)Urticaria erythematous (reddened), irregular, elevated patches of the skin; associated with intense itching
Angioedema Localized non-pitting swelling of the submucosal or subcutaneous tissue
DIAGNOSISDiagnosis of anaphylaxis is made clinically Measurement of acute and convalescent serum mast cell tryptase confirms the diagnosis in difficult cases
TREATMENT OF ANAPHYLAXIS
1. Assessment of airways:clear the airway from dentures and secretionsendotracheal intubation and oxygen therapy may be needed2. Adrenaline: (0.3 – 0.5 ml of 1:1000 sol.) IM & agonist inhaler (salbutamol)3. IV fluids (normal saline)4. Antihistamines (chlorpheneramine)5. Corticosteroids (hydrocortisone)