Asthma Flashcards
1
Q
What is asthma?
A
- Condition of atopy characterised by chronic inflammatory airway disease
- A disease of small airways with expiratory airflow limitation
- Inflammation is usually reversible
2
Q
What causes inflammation of the small airways?
A
- Smooth muscle constriction
- Hypertrophy
- Mucus production
3
Q
What is the pathophysiology of asthma?
A
- Chronic inflammatory process
- Susceptibility
- Variable airflow obstruction
- Airway hyper-responsiveness
- Reversibility
4
Q
What happens in asthma?
A
- Airway smooth muscle: hyperresponsiveness, constriction, thickening
- Sub-epithelial inflammation and fibrosis
- Mucus hypersecretion and impaired mucus clearance
- Increased eosinophils and/or neutrophils in airway lumen
5
Q
What is the immediate response in asthma?
A
- Type 1 hypersensitivity reaction
- IgE antibodies recognise antigens
- Mast cell degranulation
- Leads to smooth muscle contraction and bronchoconstriction
6
Q
What is the late phase response in asthma?
A
- Type 4 hypersensitivity reaction
- Chronic inflammation
- Caused by eosinophils, mast cells, lymphocytes, neutrophils
- Ultimately leads to: sub-epithelial inflammation/fibrosis, mucus hypersecretion, airway remodelling
7
Q
What is the typical presentation of asthma?
A
- Dry cough, worse at night
- Wheeze
- Breathlessness
- Chest tightness
- Symptoms triggered by precipitating factors
- PMH of atopy
8
Q
What might you find on examination of a patient with asthma?
A
- Wheeze (expiratory)
- Rapid respiratory rate
- Low oxygen saturations
- Use of accessory muscles
- Signs of atopy e.g. eczema
9
Q
What is atopy?
A
- A pre-disposition to an immune response and allergy
- E.g. hay fever, eczema, asthma
10
Q
What are some triggers of asthma?
A
- Allergens - pollen, pets
- Dust
- Cigarette smoke
- Cold weather
- Exercise
- Infection
11
Q
What are the options for investigating asthma?
A
- Test for airway obstruction: spirometry and bronchodilator reversibility
- Test for variability: reversibility, PEF charting, challenge tests
- Test for eosinophilic inflammation or atopy: FeNO, blood eosinophils, skin-prick test, IgE
12
Q
What is peak flow?
A
- Most common, easiest and cheapest way to investigate asthma
- Get patient to breathe as hard and fast as they can
- Based on age, height, gender
- Lower peak flow in asthmatics due to narrow airways
- Harder to breathe out (small airways collapse on expiration)
13
Q
What is FEV1 in spirometry?
A
- Total volume of air you can breathe out in one second after maximum inspiration
14
Q
What is forced vital capacity?
A
- Total volume of air you can exhale from maximal expiration
15
Q
What is seen in spirometry in asthmatics?
A
- Reduced expiratory flow rate and volume
- Descent is not linear (scalloped out)
- Reversible i.e. improves after salbutamol is given
