Asthma Flashcards
Define asthma
Chronic inflammatory airway disease characterised by variable reversible airway obstruction, airway hyper-responsiveness & bronchial inflammation
Aetiology of asthma
2 contributors
Genetic factors
Environmental factors
Aetiology of asthma - genetic
2
FH
Atopy
Aetiology of asthma - environmental
7
House dust mites Pollen Pets Cigarette smoke Viral respiratory tract infections Aspergillus fumigatus spores Occupational allergens
Define atopy
tendency for T lymphocytes to drive production of IgE on exposure to allergens
Presenting symptoms of asthma
4
Episodic hx/diurnal variation
Wheeze
Breathlessness
Cough (worse in morning & at night)
Precipitating factors for asthma
5
Cold Viral infection Drugs (e.g. β-blockers, NSAIDs) Exercise Emotions
Checks in history for asthma
2
Check for history of atopic disease (e.g. allergic rhinitis, urticaria, eczema)
Ask about any previous hospitalisation due to acute attacks —> idea of severity
Signs of asthma on physical examination
5
Tachypnoea Use of accessory muscles Prolonged expiratory phase Polyphonic wheeze Hyper inflated chest
Signs of asthma on physical examination - severe attack
4
PEFR < 50% predicted
Pulse > 110 bpm
RR > 25/min
Inability to complete sentences
Signs of asthma on physical examination - life threatening attack
(7)
PEFR < 33% predicted Silent chest Cyanosis Bradycardia Hypotension Confusion Coma
Investigations for ACUTE asthma
8
Peak flow Pulse oximetry ABG CXR - to exclude other diagnoses (e.g. pneumonia, pneumothorax) FBC - raised WCC if infective exacerbation CRP U&Es Blood & sputum cultures
Investigations for CHRONIC asthma
4
Peak flow monitoring - often shows diurnal variation w/ dip in morning
Pulmonary function test (obstructive)
Bloods
(eosinophilia
IgE level
Aspergillus antibody titres)
Skin prick tests - helps identify allergens
Management for ACUTE asthma
15
1) High flow oxygen (100% via non rebreather, aiming 94-98%)
2) Nebulisers (can do both, with 6L/min O2 over 30-60 mins)
* Salbutamol (5mg & back-to-back PRN)
* Ipratropium bromide (0.5mg 4 hrly)
3) Steroids
* 100mg IV hydrocortisone
* Or 50mg prednisolone PO 5 days
4) Magnesium sulphate IV + senior support
5) Further support
* Consider IV aminophylline infusion
* Consider IV salbutamol
* ITU/anaesthetics for intubation
MONITORING
* ECG & electrolytes closely as bronchodilators & aminophylline cause a drop in K+
* Monitor O2 sats, ABG & PEFR every 15-30 min pre & posts SABA
Why is normal PCO2 a bad sign in asthma attack
During an asthma attack they should be hyperventilating & blowing off CO2 —> should be low
Normal PCO2 suggests patient is fatiguing
Acute asthma discharge when:
7
- PEF > 75% predicted
- Diurnal variation < 25%
- Stable on discharge medication for 24 hrs
- PO steroids for 5 days
- TAME advice
- Follow up
- GP review in 2 days
- Resp clinic review in 4 weeks (if admitted)
Epidemiology of asthma
adults, children, prevalence
Affects 10% of children
Affects 5% of adults
Prevalence appears to be increasing
Management for CHRONIC asthma - step 1
2
Inhaled short acting β2 agonist used as needed
If needed >1/day move to step 2
Management for CHRONIC asthma - step 2
+ regular inhaled low dose steroids (beclometasone 400 mcg/day)
Management for CHRONIC asthma - step 3
3
+ inhaled long acting β2 agonist (LABA)
If inadequate control w/ LABA, increased steroid dose (800 mcg/day)
If no response to LABA, stop & increase steroid dose (800 mcg/day)
Management for CHRONIC asthma - step 4
2
Increase inhaled steroid dose (2000 mcg/day)
+ 4th drug (e.g. leukotriene antagonist, slow release theophylline or β2 agonist tablet)
Management for CHRONIC asthma - step 5
3
Add regular oral steroids
Maintain high dose oral steroids
Refer to specialist care
TAME
Management for asthma - advice
4
- Technique for proper inhaler use
- Avoidance – allergens, smoke, dust
- Monitor PEFR (2-4x daily)
- Educate – specialist nurse, compliance, emergency action plan
Complications of asthma
6
Growth retardation Chest wall deformity (e.g. pigeon chest) Recurrent infections Pneumothorax Respiratory failure Death
