Asthma Flashcards
What is asthma?
Chronic inflammatory disorder of the airways resulting in episodes of reversible bronchospasm causing airflow obstruction. ; ass/w airway hyper-responsiveness to endogenous or exogenous stimuli.
Epidemiology of asthma?
- Common 10-15% children
- Most children significantly improve in adolescence
- Often FHx of atopy
What is the pathophysiology of asthma progression?
Airway obstruction –> V/Q mismatch –> hypoxemia –> increased ventilation –> decreased PaCO2 –> increased pH and muscle fatigue –> decreased ventilation –> decreased PaCO2 and pH.
What are the triggers for asthma?
- URTIs
- Allergens
- Irritants
- Drugs (NSAIDS, Bblockers)
- Preservatives (sulphites, MSG)
- Other (cold air, exercise, emotion)
What are the symptoms of asthma?
-Dyspnoea esp nocturnal
-Wheezing
-Chest tightness
-Cough (dry; esp nocturnal)
-Sputum (some)
REVERSIBLE - good and bad days.
Red flags in asthma?
- Severe tachypnea / tachycardia
- Respiratory muscle fatigue
- Diminished expiratory effort
- Cyanosis
- Silent chest
- Decreased LOC
Ix in asthma?
- SaO2
- ABGs
- RFTs (when pt stable)
Explain the changes in PaCO2 in asthma attack?
- Decreased: mild asthma due to hyperventilation
- Normal or increased: ominous sign -> pt no longer able to hyperventilate (worsened airway obstruction or resp muscle fatigue)
Broad management of asthma?
- Avoid tigers
- Pt education e.g. asthma action plan
- Pharmacological: symptomatic and preventative
What are the symptomatic Rx for asthma?
- SABA / LABA
- Anticholinergics
- Oral steroids
What are the long term/preventative Rx for asthma?
- Inhaled/oral corticosteroids
- Anti-allergic agents
- LABA
- Menthylxanthine
- Anti IgE Abs
What is the emergency management of asthma?
- Oxygen
- Inhaled B2 agonist regularly
- Systemic steroids PO prednisolone or IV hydrocortisone
- Add anticholinergic
- Rapid sequence intubation in life threatening cases
- SC/IV adrenaline, IV salbutamol if unresponsive
- Corticosteroids therapy at d/c
What is the pathophysiology of acute asthma?
-Mediator release from mast cells and eosinophils
(histamine, PGs, LTs and cytokines) in response to allergen
This produces bronchoconstriction, oedema and mucous.
What are the features of airway remodelling in asthma?
- Smooth muscle and goblet cell hyperplasia
- Thickening of BM
What is the outcome of the airway remodelling in asthma?
Airflow limitation and airway hyperresponsiveness (due to increased mucous secretion, oedema and SM contraction).
Signs in asthma attach?
- Anxiety
- Tachypnoea
- Cyanosis
- Increased WOB and hyperinflation (due to bronchospasm)
- Accessory muscle use
- Susternal intercostal retraction
- Prolonged expiratory phase with wheeze
- Reduced breath sounds
- Pulsus paradoxus
How is asthma diagnosed?
PEF: 20% variation day to day OR
-Spirometry: 200mL and 12% improvement with bronchodilator
Investigation if spirometry unremarkable?
Broncho provocation testing: measures pathophsyological features of bronchial hyper responsiveness.
What aerate types of broncho provocation testing?
Direct: methacholine, histamine
Indirect: hypertonic saline, eucapneic hyperventilation, mannitol
What are alternative causes of wheeze?
- Asthma
- Bronchitis
- COPD exac
- Vocal cord dysfunction
- Obstructing endobronchial lesion (may have focal wheeze)
What are the goals of asthma treatment?
- Control symptoms
- Prevent exacerbations
- Maximise lung function and prevent decline
- Maintain normal activity
- Lowest dose Rx to achieve suitable control and minimise AEx
What are the local AEx of ICS asthma therapy?
-Hoarse voice
-Thrush
Need to rinse mouth after
What are the reasons for poor compliance with asthma Rx?
- Symptom remission
- Multiple Rx
- Chronicity of asthma
- Cost
- Poor understanding
- Cultural issues
What are the RFx for increased risk of death from asthma?
- previous life threatening ep
- recent hospitalisation for asthma
- poor psychosocial supports
- poor adherence to preventative treatments
- difficulty accessing treatment
