anaphylaxis Flashcards
what is anaphyaxis
an acute multi organ reaction to known allergen. causes vascular collapse and severe reduction to tissue perfusion.
what is the physical response to anaphylaxis
smooth muscle spasm in respiratory and GI tract. increased mucous secretion. airway oedema. vascular permebaility. decreased vascular tone.
whats the difference between anahylactic and anaphylactoid reactions
anaphylactic=immune mediated reactions, immunogoblin (ige) involve prior sensitisation
anaphylactoid=chemically mediated. non ige mediated reactions. direct activation of mediators.
what releases chemical mediators
mast cells and basophils
what does histamine do
cause vasodilation, increased vascular permeability, cardiac contraction, glandular secretion.
what do leukotrines do
cause broncho constriction, increased vascular permeability.
what do prostoglandid D2 do
cause broncho constriction, pulmonary and coronary vasocontriction
what do platelet activating factor do
cause broncho constriction, increased vascular permebaility
what is the initial medication for anaphylaxis
Adrenaline must be given intramuscular, 0.5mg and repeated after 5 minutes if no response
what can intravenous adrenaline do
cause life threatening hypertension, tachychardia, arythmias, myocardial ischemia.
what are the secondary medications for anaphylaxis
antihistamines, hydrocortisone
how does adrenaline work
blocks the physiological effects of the mediators which are causing extreme vasodilation by vasoconstriction, increasing contractility and heart rate, relaxing bronchial smooth muscle, supressing histamine and leukotrine release, attenuating severity of IGE- a mediated allergic reaction due to beta 2 receptors on mast cells and can have an adverse affect on the myocardium causing ischemia chest pain.
