Lecture 13-Asthma Flashcards
Define asthma
Chronic inflammatory disorder of the airways
What are the five defining characteristics of asthma?
- chronic inflammatory process
- variable airflow obstruction
- airway hyper-responsiveness
- reversibility
- susceptibility
Why is expiration difficult in asthmatic patients?
Bronchoconstriction, airway wall thickening and increased mucus secretion
Complete the sentence: asthma is a chronic inflammatory process, driven by ___ cells which release cytokines to activate inflammatory cells (mostly ____ cells and __________). B cells are also activated and these produce Ig_
Th2
mast
eosinophils
E
Describe the immediate response of exposure to the antigen causing bronchoconstriction
Type I hypersensitivity: interaction of allergen and IgE -> mast cell degranulation and release of histamine -> bronchoconstriction
Describe the late phase response of exposure to the antigen causing airway inflammation
Type IV hypersensitivity: eosinophils, mast cells, lymphocytes and neutrophils release mediators and cytokines -> airway inflammation
How can airway inflammation cause airway narrowing?
- oedema
- thickening of bronchial walls
- mucus over-production
- SM contraction
True or false: long term, poorly controlled asthma can cause airway remodelling
TRUE
Describe the major precipitating factors for asthmatic attacks
- allergens eg pollen, house dust mite faeces
- cold air
- exercise
- fumes
- cigarette smoke
- perfume
- stress
When is there an increased probability that presenting symptoms are due to asthma?
- one or more symptoms of wheeze, SOB, cough, chest tightness
- symptoms worse at night/early morning
- symptoms vary over time and in intensity
Why can symptoms be worse at night/early morning?
Higher parasympathetic tone -> bronchoconstriction
When is there a decreased probability that presenting symptoms are due to asthma?
- isolated cough with no other resp symptoms
- chronic sputum production
- SOB with dizziness
- chest pain
- exercise-induced dyspnoea
When can wheezing be absent in an asthmatic patient?
“Silent chest” = severe asthma exacerbations
True or false: asthmatic patients have an increased FEV1/FVC
FALSE - reduced
How does asthma present?
- expiratory wheeze
- cough
- diurnal variability
- difficulty breathing
- chest tightness
- exercise-induced wheeze
- atopic history
What is the treatment plan if there is a high probability of asthma?
- 6 weeks inhaled corticosteroids/2 weeks prednisolone
- salbutamol (relieves symptoms but doesn’t treat inflammation)
What is the SIMPLE treatment plan?
S=smoking cessation I=inhaler technique M=monitor P=pharmacotherapy L=lifestyle changes E=education
When is a patient diagnosed with acute severe asthma?
Any one of: -PEF 33-50% -Resp rate more than 25/min HR more than 110/min -inability to complete sentences in one breath
When is a patient diagnosed with life threatening asthma?
All symptoms of acute severe, plus any one of:
- altered conscious level
- exhaustion (SpO2 < 92%)
- arrhythmia
- hypotension
- cyanosis
- silent chest
How is acute severe asthma treated?
- O2, high flow
- nebulised salbutamol, O2 drive
- oral prednisolone
- if the above don’t work, add nebulised ipratropium bromide and IV Mg2+
