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
