Asthma Flashcards
Define:
Chronic inflammatory airway disease characterised by reversible airway obstruction
Type 1 hypersensitivity
Aetiology:
Both genetic (family history and atopy) and environmental factors.
An environmental factor leads to mast cell and basophil degranulation.
Leads to:
Increased mucus production
Bronchial muscle constriction
Mucosal swelling and inflammation
What are some environmental triggers:
House and dust mites Pollen Pets Cigarette smoke Viral resp infection Aspergillus Occupation
Epidemiology:
10% in children
5% in adults
more common if history of atopy
Symptoms:
SOB Chest pain Cough Sputum wheeze ^ worse in the morning and at night
Participating factors:
- cold air
- emotions
- exercise
- drugs
- viral infection
- pollution
History of atopic disease
Diurnal variation with marked reduced peak flow in the morning
40-60% have GORD
Signs:
Tachypnoea use of accessory muscles prolonged expiratory phase polyphonic wheeze hyperinflated chest hyper-resonant percussion reduced air entry
How would you define a moderate attack:
PEFR: >50-75% predicted
How would you define a severe attack:
o PEFR 35-50% predicted
o Pulse > 110/min
o RR > 25/min
o Inability to complete sentences
How would you define a life threatening attack:
o PEFR < 33% predicted o Silent chest o Cyanosis – PaO2 <8kPa, normal/high PaCO2 >4.6kPa, low pH <7.35 o Bradycardia o Hypotension o Confusion o Coma • Near fatal: raised PaCO2 +/- require mechanical ventilation
What is the general management for an acute asthma attack:
O2 therapy Salbutamol (SABA) Ipatromum bromide (SAMA) Iv magnesium Corticosteroid (oral prednislone and iv hydrocortisone)
Investigations:
Peak flow ABG Bloods - CRP, U+ E's, blood + sputum culture CXR Pulse ox
If chronic:
- Peak flow on at least three days shows diurnal variation with dip in the morning (>20% variation)
- GOLD STANDARD: Pre- and post-bronchodilator spirometry – shows obstructive defect and usually a >15% improvement in FEV1 following b2-agonist or steroid trial
CXR: hyperinflation
Bloods - check: • Eosinophilia • IgE level • Aspergillus antibody titres o Skin prick tests - helps identify allergens o Aspergillus serology
How would you treat an acute asthma attack:
o ABCDE approach
o Give O2 and monitor O2 sats, ABG, PEFR
o 5mg salbutamol nebulised every 15 mins
o 0.5mg ipratropium bromide nebulised
o 100mg IV hydrocortisone OR 40mg PO prednisolone
o If no improvement: 1.2-2 mg IV Magnesium sulfate over 20mins AND get senior help
o Note: must monitor ECG for arrhythmias due to electrolyte disturbances
o If still no improvement: IV aminophylline
o If still no improvement: intubation and ventilation in ICU
- Treat underlying cause (e.g. infection)
- Give antibiotics if it is an infective exacerbation
- Monitor electrolytes closely because bronchodilators and aminophylline causes a drop in K+
- Invasive ventilation may be needed in severe attacks
What is the chronic treatment for asthma:
o STEP 1
•Inhaled SABA e.g. salbutamol used as needed for symptom relief, AND regular inhaled low-dose steroids e.g. beclometasome
o STEP 2
•Step 1 + inhaled LABA e.g. salmeterol 50ug/12h by inhaler
• If benefit but inadequate control with LABA, increase step 1 steroid dose (800 mcg/day) OR add a 4th drug
• If no response to LABA, stop LABA and increase steroid dose (800 mcg/day)
o STEP 3 – refer to specialist at this point
• Increase inhaled steroid dose (2000 mcg/day)
• Add 4th drug (e.g. leukotriene antagonist, slow-release theophylline or beta-2 agonist tablet)
o STEP 4
• Add regular oral steroids – prednisolone 1 dose daily, at lowest possible dose
• Refer to specialist asthma care
Complications:
Respiratory failure Death Pneumothorax growth retardation Recurrent infections Chest wall deformities
Prognosis:
Improves with age
In adults likely to be chronic
