Asthma Flashcards
What is meant by asthma?
Chronic inflammatory disease
of the airways of the lungs
What parts of the airways are affected with asthma?
Conducting zone
bronchi and bronchioles
What causes an acute episode of asthma?
Environmental triggers are inhaled into the bronchi and bronchioles
What are some examples of environmental triggers that cause acute episodes of asthma?
Allergens - pollen, mould, pets, dust
Viral infection
Tobacco smoke
Smoke
Exercise
Cold air
How do environmental triggers cause an acute episode of asthma?
Stimulate an immune response in the bronchi and bronchioles
What are the main types of cells immune involved in asthma?
Mast cells
T cells
Eosinophils
Neutrophils
How are mast cells activated?
Have IgE on their surface
IgE binds to allergen
What do mast cells do when they are activated?
Degranulate
which releases histamine
What does the immune response cause in acute episode of asthma?
Inflammation of the bronchi and bronchioles
- mucosal oedema
- more and thicker mucus secreted
- bronchoconstriction
What are the effects of inflammation of the bronchi and bronchioles in an acute episode of asthma?
Narrowing of bronchi and bronchioles
increased airway resistance
worse with expiration
What are the effects of repeated inflammation of the bronchi and bronchioles?
Desquamation of epithelium
Mucous glands hyperplasia
Smooth muscle hyperplasia
Bronchial hyper-reactivity
What is meant by bronchial hyper-reactivity?
Bronchial smooth muscle is more sensitive
contracts more easily
contracts in spasms
Why does repeated inflammation of the bronchi and bronchioles cause bronchial hyper-reactivity?
Damage to mucosa of bronchi and bronchioles
exposes sensory nerve endings
What are the symptoms of asthma?
Wheezing
Shortness of breath
Chest tightness
Cough
How do the symptoms of asthma vary?
Vary in occurrence, frequency, intensity
-worse at night, early morning
Why are symptoms of asthma worse at night/early morning?
Natural bronchoconstriction at this time
narrows airways further
How is asthma diagnosed?
History of airway inflammation and airway hyper-reactivity, symptoms
Wheezing on auscultation
Reduced expiratory air flow
Eosinophil count
How is reduced expiratiry air flow measured with asthma?
Spirometry - low FEV1, same FVC, low FEV1/FVC ratio
Volume-time graph - flatter gradient, same peak
Flow-volume graph - lower peak, scooped shape, reaches same volume
Abnormalities show with acute episodes, reverse with bronchodilator, treatment
What are the problems with measuring reduced expiratory air flow with asthma?
May not show when being measured
because asthma varies in occurence, frequency and intensity of symptoms
How can the airways be challenged to react in order to measure reduced expiratiory airflow?
Give histamine
won’t affect a normal person’s airways
will cause airways of person with asthma to narrow
What are eosinophils measured in with asthma?
Blood
Induced sputum
How is asthma treated?
6 weeks inhaled corticosteroids
B2 agonist used when symptomatic
What is an example of an inhaled corticosteroid?
Budesonide
What is an example of a B2 agonist?
Salbutamol
How do corticosteroids treat asthma?
Reduce inflammation
How does a B2 agonist treat the symptoms of asthma?
Bronchodilation
What is an asthma exacerbation?
Worsening of symptoms
doesn’t respond to usual treatment
What are the signs of a severe asthma exacerbation?
Altered consciousness
Cardiac arrythmias
Hypotension
Cyanosis
Silent chest
Low pO2, low O2 saturation
Normal or high pCO2
How is a moderate asthma exacerbation treated?
Oxygen
Nebulised salbutamol
Oral corticosteroid
What is an example of an oral corticosteroid?
Prednisolone
How is a severe asthma exacerbation treated?
Nebulised anticholinergic
IV magnesium or IV aminophylline
Why is there wheezing on auscultation with a patient with asthma?
Sound of air moving through narrowed, obstructed airways
What is an example of an anticholinergic
Ipratropium
