Asthma Flashcards
How many deaths per year are attributable to asthma?
300
Is asthma more common in children or adults?
Children
Describe the pathophysiology of asthma
Acute: mediator release from mast cells and eosinophils (including histamine, PGs, leukotrienes and cytokines) in response to allergen induces bronchoconstriction, airway oedema and mucous production
Chronic inflammation: early structural changes involving cell recruitment and epithelial damage
Airway remodelling: smooth muscle and goblet cell hyperplasia, and thickening of basement membrane
Leads to airflow limitation and airway hyperresponsiveness (AHR)
Greg is a 16 year old boy brought in to the GP surgery by his mother
Has been complaining of increased SOB and wheeze, particularly at night
Mother is wondering if he might have asthma; what features on Hx would help you make a diagnosis of asthma?
SOB (often episodic, particularly nocturnal or early morning, often with exercise)
Wheezing
Chest tightness
Cough (dry or with some sputum production)
Reversible (recurrent with good and bad days, responds to medication but may resolve spontaneously)
May be certain triggers
List 4 predisposing factors for asthma
Genetic predisposition (no single gene)
Atopy (including allergic rhinitis)
Airway hyperresponsiveness (AHR)
Sex (severe persistent asthma more common in women)
What is atopy?
Syndrome characterised by a tendency to be “hyperallergic”
Typically presents with one or more of the following: eczema (atopic dermatitis), allergic rhinitis or allergic asthma
List 9 common asthmatic triggers
Allergens Pollutants (e.g. tobacco smoke, occupational fumes) URTIs Exercise Changes in weather Emotion, anxiety Food, additives Medication GORD
Give 2 examples of medications which can precipitate an acute asthma attack
Aspirin
Beta blockers
What clinical features are present on examination in a patient not having an active asthma attack?
No abnormal findings if not active (asthma is completely reversible)
What clinical features are present on examination in a patient suffering an acute asthma attack?
Anxiety Tachypnoea Cyanosis Pursed lip breathing Use of accessory muscles Substernal intercostal retraction Auscultatory findings: prolonged expiratory phase with wheeze, reduced breath sounds, reduced heart sounds Pulsus paradoxus
Describe the pathophysiology of an acute asthma attack
Bronchospasm leads to increased work of breathing and hyperinflation (pursed lip breathing eases this)
Compensation through increased effort (elevated RR, accessory muscle activation, substernal intercostal retraction)
What process produces wheeze?
??
What is the criteria for pulsus paradoxus?
> 10 mmHg drop in SBP with inspiration
Greg has been having episodic SOB and wheezing on and off over the last 4 months; the symptoms often occur at night and with exercise
FHx: sister with asthma who uses ventolin (he sometimes borrows it to help his symptoms)
PHx: allergic rhinitis, wheezy episodes with URTIs as a young child
O/E: normal
Do you think Greg has asthma? Why? How might you confirm your clinical suspicion?
Yes; sounds like reversible airflow obstruction but would need to demonstrate in the clinical setting using objective measures of lung function
What criteria on lung function testing confirms a diagnosis of asthma?
PEF: 20% variation day to day (or morning to evening)
Spirometry: 200mL and 12% improvement with bronchodilator
What is the principle underlying bronchoprovocation testing?
Measures the pathophysiological feature of bronchial hyperresponsiveness
What are the different types of bronchoprovocation testing?
Direct: methacholine, histamine
Indirect: hypertonic saline, eucapneic hyperventilation, mannitolp
List 6 possible causes of wheeze
Asthma Bronchitis Exacerbation of COPD Vocal cord dysfunction Obstructing endobronchial lesion (e.g. tumour, foreign body; may have focal wheeze) HF
Greg has normal baseline spirometry but does have evidence of AHR on provocation testing. He also has positive skin prick test to allergens including grasses and house dust mite.
What should we do next? Would you begin treatment? What are the principles of treatment?
PATM:
Patient focussed treatment: what are the patient’s goals? Provide education, construct an action plan, consider psychosocial factors
Avoid triggers
Treat conditions that could exacerbate asthma
Medication
What are the 5 goals of asthma treatment?
Control symptoms
Prevent exacerbations
Maximise lung function and prevent future lung function decline
Maintain normal levels of activity
Lowest dose of medication to achieve suitable asthma control and minimise side effects
List 5 classes of asthma medications
B2 agonists (symptom relievers) Inhaled corticosteroids (preventers) Oral corticosteroids Combination inhalers (ICS/LABA) Leukotriene receptor antagonists Anti-IgE
What is the mechanism of action of B2 agonists?
Relax smooth muscle to improve airway patency
Does not change the underlying inflammation
What is the mechanism of inhaled corticosteroids?
Reduces airway inflammation and AHR
You decide to start Greg on twice daily ICS and as required B-agonist
What advice would you give him about taking the ICS and potential side effects?
ICS must be taken regularly (symptoms of asthma may take a few weeks to settle)
Type of delivery device varies
Local adverse effects include hoarse voice and oral thrush (need to rinse mouth after medication, but not as bad with ciclesonide)
Systemic effects are not common in very high doses
Greg is now 19. He initially had a significant improvement in his asthma symptoms once commencing his ICS. However, over the last few months he has noticed symptoms of wheeze 2-4 times a week interfering with sports. Nocturnal waking every 2nd or 3rd night.
He uses a ventolin inhaler when needed, He is emptying 3 puffers a month. He has taken up smoking in the last 2 years (10/day). His hay fever has been particularly bad this year.
What do you think of Greg’s asthma control? Is there anything else you would like to ask? Why might this have happened?
Asthma control is poor
Want to know underlying psychosocial factors impacting his control, what his medication compliance has been like and what his puffer technique is
Greg’s asthma control is poor. He stopped his ICS regularly about 6 months ago. He is quite anxious as he is having trouble with his girlfriend and he is not doing well in his studies at university.
When you check his puffer technique, it is poor, and he has not been using his spacer device.
How might the situation be improved?
Ask Greg what he sees are the issues and check what he would like to do
Education to improve adherence, along with an asthma plan
Improve medication delivery
Treat his allergic rhinitis
Stop smoking
Restart ICS +/- LABA (he might have more severe asthma than first thought)
Regular review
What are the rates of non-adherence for asthma medication?
30-70%
List 6 reasons which may underlie the high rates of non-adherence for asthma medication?
Symptom remission
Multiple medications, fear of dependence and long term side effects
Chronicity of asthma
Cost
Poor understanding (particularly with preventer meds), poor supervision
Cultural issues
Greg is now 23. He has been fairly well although compliance with his medication is still quite poor. He is still smoking.
He now presents to the ED with severe dyspnoea for 3 hours on the background of a bad URTI for the last 3 days. Ventolin has only provided minor relief.
At presentation he is anxious and tachypnoeic, speaking in very short sentences.
His HR is 120, BP 130/70, saturation 89% on room air, RR 32
His chest is quiet with faint, high pitched whistling throughout the chest.
CXR shows hyperinflation
ABG pH 7.43, PaCO2 40mmHg, PaO2 58 mmHg, HCO3 24
Greg has a severe life threatening attack of asthma
How should we treat this severe episode?
O2 Oral prednisolone or IV hydrocortisone Regular bronchodilators Urgent ICU assessment for observation and possible intubation IV magnesium
List 5 risk factors which increase morbidity from asthma
Previous life threatening attack of asthma
Recent hospitalisation for asthma
Poor psychosocial supports
Poor adherence to preventative treatments
Difficulty accessing treatment
