Asthma Flashcards
What is asthma?
Chronic inflammatory disease of the airways
What can trigger asthma?
Infection Allergens Irritants Drugs Temperature Exercise
What is the pathophysiology of asthma?
Hypersensitivity inflammatory reaction
Charactersied by the T-helper 2 response, eosinophils, and mast cells
Cells release histamine, prostaglandins and leukotrienes
Increased number of goblet cells
Smooth muscle hyperplasia
Hypertrophy
What is involved the T-helper 2 response?
IL 4 - promotes differentiation of T cells
IL 5 - promotes production of B cells
IL13 - promotes goblet cells, hyperplasia, hypertrophy and mucus secretion
TNF-a - acute phase protein
Leukotriene LTB4 - triggers contraction in airways
Mast cell tryptase - found in allergic response
What occurs in baseline asthma?
Chronic inflammation
Thickening of basement membrane
Hypertrophy of airway muscle
What happens in acute asthma?
Bronchospasm
Excessive mucus production
What are the symptoms of asthma?
Intermittent
- dyspnoea
- wheeze
- cough
What are signs of asthma?
Tachypnoea
Audible wheeze
Hyperinflated chest
Hyperresonant percussion
What investigations should be done for acute asthma?
Peak flow
Bloods
CXR
Spirometry
What is the spirometry pattern in asthma?
Obstructive
Reduced FEV1
Reduced FVC
Can be reversed with bronchodilators
How is baseline asthma classified?
Mild intermittent
- symptoms <2 week
- brief attacks
- FEV1 > 80 predicted
Mild persistent
- symptoms >2 week, <1 day
- attacks effect activity
- FEV1 >80
Moderate persistent
- daily symptoms
- affect activity
- FEV1 60-80
Severe persistent
- continuous symptoms
- limited physical activity
- FEV1 <60
How is acute asthma classifed?
Moderate
- PEFR 50-75%
Acute severe
- PEFR 33-50%
- RR >25
- HR >110
- inability to complete sentences in one breath
Life threatening
- PEFR <33%
- SpO2 <92%
- PaO2 <8
- cyanosis
- poor respiratory effort
- normal PaCO2
Near fatal
- Raised PaCO2
How is baseline asthma managed?
Step 1 = SABA
Step 2 = SABA + low dose inhaled corticosteroid
Step 3 = LABA + ICS
Step 4 = increase ICS dose OR add LTRA
Step 5 = add oral prednisolone
How is acute asthma managed?
OH SHIT MAN
Oxygen titrated to 94-98% Salbutamol nebs Hydrocortisone IV Ipratropium bromide nebs Theophylline/Aminophylline Magnesium sulphate IV Anaesthetist intervention NIV/intubation
What are the criteria for safe discharge?
PEFR >75% 5 days abnormal prednisolone Asthma nurse to assess inhaler technique GP follow up within 2 days Respiratory clinic follow up within 4 weeks
