Asthma Flashcards
Asthma
chronic respiratory condition characterised by recurrent episodes of airflow obstructions, bronchial hyperresponsiveness, and underlying inflammation
Aetiology of asthma
- genetics (FHx.)
- environment (allergens, air pollution)
- infections (viral URTIs)
- sensitisation and atopy (eczema, rhinitis, food allergies)
- sociodemographics (lower status, rural vs. urban)
- lifestyle (diet and exercise)
Risk factors for asthma
- personal or FHx. of atopy
- antenatal exposure (smoking)
- low birthweight
- not breastfed
- high allergen exposure
- high air pollution
- the ‘hygeine hypothesis’
Pathophysiology of asthma
- airflow obstruction (smooth muscle contraction by mast cells, eosinophils)
- mucous hypersecretion
- bronchial inflammation (from IgE dependent mast cell degranulation)
- ** airway hyperresponsiveness**
- airway remodelling
Symptoms of asthma
Cough:
- nocturnal
- dry
- non-productive
SOB:
- exercise
- cold air
- allergens
Clinical signs of asthma
Wheeze:
- expiratory
- polyphonic
Increased work of breathing:
- tachypnoea
- accessory muscle use
- head bobbing
- nasal flaring
In severe exacerbations:
- altered mental status
- silent chest
- cannot finish sentences
- significant tachycardia
- exhaustion
Investigating suspected asthma
- Spirometry with bronchodilator reversibility
- FeNO levels
- Peak expiratory flow diary
Spirometry results in asthma
- > 5 years old
- FEV1/FVC ratio < 70% (obstructive)
- Bronchodilator reversibility +ve
Results of bronchodilator reversibility test in asthma
For 5-16 years & > 16 years
5-16:
- increase > 12% FVC
> 16:
- increase > 12% FVC
- increase > 200ml volume
FeNO results in asthma
For 5-16 years & 16+ years
5-16:
- FeNO > 35
16+:
- FeNO > 40
Peak flow findings in asthma
when measured for 2-4 weeks
more than 20% variability
Differentials for asthma in children
- ciral induced wheeze
- bronchiolitis
- inhaled foreign body
- cystic fibrosis
- structural airway disease (e.g. bronchomalacia)
Stepwise treatment ladder in asthma
- SABA
- SABA + low-dose ICS
- SABA + low-dose ICS + LTRA (montelukast)
- SABA + low-dose ICS +/- LTRA + LABA
- SABA +/- LTRA + MART
- SABA +/- LTRA + medium-dose MART
- SABA +/- LTRA + high-dose ICS or theophylline
MART Regimen in Asthma
- Maintenance & reliever therapy
- Form of combined ICS and LABA
Complications of asthma
- status asthmaticus
- pneumonia
- COPD
- pneumothorax
- airway remodelling
- osteoporosis (long term steroids)
- anxiety and depression (living with chronic disease)
Managing mild-moderate asthma exacerbation
First line:
- SABA 4-10 puffs/20mins
- oral corticosteroid
Consider:
- inhaled anticholinergic (ipratropium)
- controlled O2
- antibiotics
Managing a severe exacerbation of asthma
First line:
- Hospital admission
- Nebulised SABA
- Oral/parenteral corticosteroid
- Controlled O2
Second line:
- Nebulised anticholingeric (ipratropium)
- Nebulised Magnesium sulfate
- IV salbutamol
Third line:
- antibiotics
- IM adrenaline
- Ventilation
Managing a life-threatening exacerbation of asthma
First line:
- ICU admission
- Nebulised salbutamol
- Oral/parenteral corticosteroid
- Controlled O2
Second line:
- nebulised anticholinergic (ipratropium)
- nebulised magnesium sulfate
- IV salbutamol
Third line:
- antibiotics
- IM adrenaline
- ventilation
Drugs used in asthma exacerbations
- salbutamol (inhaled, nebulised, IV)
- corticosteroids (oral, parenteral)
- ipratropium (nebulised)
- magnesium sulfate (nebulised)
Discharge criteria for asthma exacerbation
- Stable on SABA every 3-4 hours
- Peak flow > 75% of best/predicted
- O2 sats > 94% in room air
Clinical features of mild/moderate asthma exacerbation
- SpO2 > 92%
- RR < 30
- No or minimal accessory muscle use
- Talking in full sentences
- Wheeze (may only be audible with stethoscope)
Clinical features of severe asthma exacerbation
- SpO2 < 92%
- PEFR 33-50% predicted
- RR > 30
- Can’t finish sentences
- HR > 125
- Use of accessory muscles
- Audible wheeze
Clinical features of life threatening asthma exacerbation
- SpO2 < 92%
- PEFR < 33% predicted
- Silent chest
- Poor respiratory effort
- Altered consciousness
- Agitated/confused
- Exhaustion
- Cyanosis