Define asthma
-long-term condition that affects your airways
-chronic inflammatory disorder of the airways which occurs in
susceptible individuals
-Inflammatory symptoms are associated with widespread/ variable airflow obstruction
and an increase in airway response to
a variety of stimuli.
-Obstruction is often
reversible
either spontaneously or with
treatment
How is it diagnosed?
There’s no single test for asthma.
But it can be diagnosed
from your
symptoms
and some breathing tests
Initial diagnosis is made using the presence of clinical signs and symptoms but requires further tests to confirm.
Investigations?
Common diagnostic tests:
• Peak expiratory flow rate (PEFR) using a peak flow meter
-measures how fast you can blow air out of your lungs in
one breath.
- variability in readings greater than 20% and at least 60mL on 3 days of a week is highly suggestive of asthma
- peak flow meter allows patients to monitor their condition on a daily basis/ when they feel an increase in their symptoms
• Spirometry
(FEV1, FVC, ratio)-
determines the severity of airway obstruction
-forced expiratory volume in 1 second, FEV1. A measure of the maximum volume of air expelled in the first second of breathing.
-forced vital capacity, FVC. A measure of the maximum volume of air it is possible for the patient to breathe out after taking maximal inspiration.
- normal airways 0.75
- asthmatic patients 0.7
- Chest X-Ray
- Blood gases
- Microbiology
- Histamine (mucus secretion + bronchoconstriction) / Methacholine (bronchoconstriction) inhalation challenge in difficult cases
How does asthma affect the airways?
Asthma Trigger- anything that irritates your airways and sets off your asthma symptoms
Difficulty in breathing leads to asthma symptoms- chest tightness, wheeze, coughing
Signs/ symptoms
Frequent and recurrent episodes of: - wheezing, - breathlessness, - chest tightness - chronic cough •Symptoms occur or worsen •At night –waking the patient •Seasonally •In the presence of stimuli •Patient may often be atopic- a form of allergy in which a hypersensitivity reaction such as eczema may occur in part of the body not in contact with the allergen •Family history - unexplained peripheral blood loss •Patient symptoms or lung function improves with adequate treatment
Non- pharmacological management
Trigger avoidance: environmental and dietary
consider primary and secondary prophylaxis
Aims of pharmacological therapy
Achieve and maintain control of symptoms
• Maintain normal activity levels, including exercise
• Maintain pulmonary function as close to normal levels as
possible
• Prevent asthma exacerbations
• Avoid adverse effects from asthma medications
• Prevent asthma mortality
What symptoms may be indicative of an alternative disease?
- significant smoking history
- symptoms only with viral infections
- voice disturbance
- normal chest examination when symptomatic
- dizziness
- chronic productive cough in absence of wheeze and breathlessness
Describe the aetiology of asthma
- hypersensitivity of the lungs to one or more stimuli
- body reacts to stimuli to produce chronic bronchoconstriction
- allergens act on macrophages, T-lymphocytes, epithelial cells and eosinophils- each produces inflammation though direct or neural mechanisms
- mast cells release histamine, leukotrienes and PG’s to induce bronchospasm
- immune response leads to marked hypertrophy and hyperplasia of smooth muscle resulting in narrowing of small airways
- bronchial gland and goblet cell hypertrophy results in excessive mucus production- often viscous. This can plug the airways in conjunction with epithelial cells and inflammatory debris
- airway becomes oedematous and mucociliary clearance is decreased
Actions of preventer
Brown inhaler- corticosteroid
- reduces number and activity of mucosal mast cells and eosinophils
- reduce inflammatory reactions such as oedema and mucous secretion
- enhance beta-adrenergic receptor numbers and sensitivity
- suppress late phase inflammatoy reactions
- prevet airway remodelling
How can patients self montior their asthma?
- peak flow meter- when comparing with individuals can show improvement/ deterioration of disease and effectiveness of treatment
- symptom diary
Step 1 of chronic management of asthma
Treatment uses a stepwise approach- aims to stop symptoms quickly and improve peak flow
- start inhaled short acting beta2 agonist (salbutamol or terbutaline sulfate) as required
- move to step 2, if required more than 2/3 weekly
- being symptomatic 3 times a week or more
- signifcant night time symptoms once a week
- asthma attack within the last 2 years
What is step 2?
- short acting beta 2 agonist
- add regular inhaled corticosteroid
e. g. belcometasone diproprionate 100-400 micrograms twice daily
Step 3
- short acting beta 2 agonist when required
- standard dose inhaled corticosteroid regularly
- long acting beta 2 agonist regularly e.g. salmetarol or formeterol
- if there is not response to LABA, disctontinue and increase dose of inhaled corticosteroid
- if asthma is not controlled, ensure corticosteroid dose is at higher end of dose range and consider adding leukotriene receptor antagonist, theophylline or oral beta 2 agonist
Step 4?
- inhaled short acting beta2 agonist when required
- high dose inhaled corticosteroid regularl
- inhaled long acting beta 2 agonist regularly
- 6 week trial of one or more of leukotriene receptor antagonist, theophyline or oral beta 2 agonist
Step 5?
- inhaled short actign beta 2 agonist when required
- high dose inhaled corticosteroid regularly
- one or more long acting bronchodilators
- plus regular oral prednisolone
When are anticholinergics used?
Ipratropium bromide & tiotripum bromide
- normally only used in acute severe asthma
- in patients with mixed asthma or COPD
Inhaled corticosteroids
- most common agents used for long term control of asthma
- dose should be at lowest effective dose for patient and should be reviewed regularly
- when reductions are appropriate- increments of 25-50% of total dose every 3 months
- doses of inhaled corticosteroids are expressed as the equivalent dose of beclometasone given via CFC-MDI
- corticosteroids are initiated in patients who have has an exacerbation within the last 2 years while using inhaled beta 2-adrenoceptor agonists 3 or more times a week, who have experiences symptoms 3 times a week, who are awakened one night a week
- adrenal suppression is unlikley to occur but is likely to occur at doses of 2mg per day
- can cause candidiasis and vocal harshness- can be minimised with the use of large- volume spacer devices and rinsing the mouth out after use
LABA
- should be trialled for 4- 6 weeks and discontinued if there’s no response
- e.g. salmetarol and formeterol
- unsuitable as relievers and should not be used without inhaled corticosteroids
Theorphylline/ aminophylline
oral bronchodilators
- narrow therapeutic window
- toxicity may present as vomiting, insomnia, fitting, arythmia, hyperglycaemia and hypotension
