Asthma basics of therapeutics and pharmacological treatments Flashcards
Epidemiology
study of distribution and determinants of health related states and events in specified populations
Extrinsic asthma
allergic - more in children ( 1/11 affected in Uk)
intrinsic asthma
non-allergic - no detectable
how many people have asthma in the uk
5.4million
Episodic
seasonal
Pets Stress Exercise Pollen Pollution Smoke Dust Cold air Fungus spores Bug Chemical fumes
all triggers of asthma
what antibody mediates asthma
IgE - formed in response to allergen
frist exposure drives sensitization and memory
preexposure - allergen binds to specific IgE molecule on the mast cell surface
what ion moving into the mast cell drives degranulation ?
what does the mast cell release
calcium
histamines and prostoglandins
Mechanism of airway narrowing in asthma
takes around 20mins to hours
Airway narrowing
Open airway - smooth muscle layer goes into spasm , narrowing the airway ,
lining of the lung becomes inflamed and then mucus production is increased blocking the airway even more than usual - in some part of the airway mucus can from plush that nearly or completely block the airway
Imagine airway picture as a circle
In the early phase of an asthma attack what happens
Allergen or non specific stimulus binds to the mast cell releasing spasmogens leading to bronchospasm.
Chemotaxins and chemokines are released by the mast cells
this leads into the late phase - what happens here
Infiltration of Th2 cells -activation of inflammatory cells such as eosinophils
These release cysLTs and other mediators
This leads to airway inflammation and airway hyperreactivity leading to bronchospasm and wheezing
What to eosinophils release that contribute to airway hyperactivity and damage epithelial lining
EMBP
ECP
common signs and symptoms of asthma
Coughing - worse at night or first in morning
Wheezing or whistling noise in the chest heard on expiration - tight airway pressure to exhale
SOB
Tightness in the chest ( dyspnoea)
dyspnoea
shortness of breath
In asthma how does FVC and FEV1 and the ratio change - on spirometry
FVC dose not change
FEV1 reduces
So ratio falls and PEFR drops
comparing moderate , acute/severe and life threatening asthma change
PEF SpO2 speech Respiration Pulse
PEF >50-70% , 33-50 , under 33
SpO2 >92 , “ , below 92
speech normal, can’t complete sentences , silent chest cyanosis or poor respiratory effort
Respiration <25/m , over 25 then hypotenison and arrhythmia
Pulse <110 then above then altered consciouness
in self management of asthma what can you do
Avoidance of triggers Desensitisation to specific allergen House dust mite control measures Smoking cessation Weight reduction