Allergy and Anaphylaxis

Question 1

antibody

Answer 1

a protein produced by certain cells in the body in the presence of a specific antigen; the antibody combines with that antigen to neutralise inhibit or destroy it

Question 2

antigen

Answer 2

any substance when introduced into the tissues or blood induces the formation of antibodies and reacts only with its specific antibodies

Question 3

IgE

Answer 3

chief culprit in allergies

Y binds to antigens, tail binds to mast cells causing them to degranulate

Question 4

allergy

Answer 4

hypersensitivity to a normally innocuous entity such as dust, pollen or certain foods

Question 5

allergen

Answer 5

an antigen that provokes a hypersensitivity reaction

Question 6

allergic

Answer 6

pertaining to or sensitive to an allergen

Question 7

atopy

Answer 7

a personal and /or familial tendency to become sensitized and produce IgE antibodies in response to ordinary exposures of commonly encountered environmental allergens
results in development of asthma, rhinoconjunctivitis, excema

Question 8

allergy

Answer 8

type 1 hypersensitivity reaction is characterised by excessive activation of mast cells and basophils by IgE resulting in a systemic inflammatory response that can result in a spectrium of symptoms

Question 9

allergic reactions

Answer 9

increased physiological response to an antigen after a previous exposure

Question 10

anaphylaxis

Answer 10

a severe life threatening systemic allergic reaction which involves one or both of two severe features: resp difficulty or hypotension

Question 11

anaphylaxis is characterised by:

Answer 11

two or more of the following within minutes to a few hours of exposure to a likely allergen: skin or mucosal involvement, airway compromise, hypotension or associated symptoms, persistent GI symptoms

Question 12

Mast cells are found in

Answer 12

all subcutaneous and submucosal tissues

Question 13

basophils are found in

Answer 13

the blood

Question 14

histamine H1 receptors cause

Answer 14

smooth muscle contraction
increased vascular permeability
prostaglandin generation

Question 15

histamine H2 receptors cause

Answer 15

increased vascular permeability
gastric acid secretion - kills bad stuff
release of more histamine from mast cells and basophils

Question 16

histamine H3 receptors cause

Answer 16

inhibition of central, peripheral nervous system neurtotransmitter release
inhibition of further histamine formation release
biofeedback loop

Question 17

leukotrines

Answer 17

potent bronchoconstrictors
increased vascular permeability
possible coronary vasoconstriction - slower onset than histamine, effects last longer

Question 18

Systemic reactions in anaphylaxis

Answer 18

vasodilation - decreased peripheral vascular resistance, hypotension, tachycardia
increased capillary permeability - tissue oedema, urticaria, itching laryngeal oedema
fluid leakage from vascular space - hypovolaemic shock, circulating blood volume decrease
urticaria - elevated skin lesions
smooth muscle spasms - bronchospasm

Question 19

ROutes of Adrenaline

Answer 19

IM - 0.3-0.5mg at 5 min intervals 
IV - 50-1000mcg a min dilute 1:1000 
nebulised - used 5mg/ml 
IO - same dose as IV
ETT - use if no IV/IO access, increase dose by 2

Question 20

Actions of Adrenaline

Answer 20

A adrenergic - increase PVR, BP and coronary artery perfusion, decrease peripheral vasodilation, angiooedema, urticaria
B1 adrenergic - positive inotrope and chronotrope
B2 adrenergic - bronchodilation

Question 21

side effects of Adrenaline

Answer 21

feeling of impending doom
marked hypertension with risk of intracerebral bleeding
increased myocardial O2 demands leading to angina and MI