Asthma clinical features in adults Flashcards
What is asthma ?
History of respiratory symptoms such as :
- wheezing - SOB - coughing - chest tightness - together with difficulty in expiration
What is the epidemiology of asthma ?
Children- 10-15% - M>F
Adults- 5-10%- F>M
Dangerous- 3 deaths/day
What is the pathophysiology of asthma ?
Airway inflammation mediated by the immune system —> narrowing of airways
—> increased airway reactivity
I
V
Airway narrowing
I I
V V
spontaneously stimuli
What are the three proven risk factors ?
Smoking
Genetics
Occupation
What are the hereditary risk factors of asthma ?
Atopy is body’s predisposition to develop an antibody- IgE in response to exposure to :
- environmental allergens and is an inherited trait- allergic rhinitis, eczema, hay fever - increased risk of asthma if 1st degree family member has asthma or atopic disease
How is smoking a risk factor of asthma ?
Maternal smoking during pregnancy:
- decreased FEV1
- increased wheeze
- increased airway responsiveness
- increased asthma
likely an epigenetic phenomenaWhat allergens can occupation expose you to ?
Isocyanates (paints) Colophony (welding solder flux) Laboratory Animals Grains Enzymes Drugs Crustaceans
What is the most important clinical aspects of asthma ?
History
What are the symptoms of asthma ?
Wheeze SOB, severity Chest tightness Cough, paroxysmal, usually dry Sputum (occasional)
What are some triggers of asthma symptoms ?
Exercise Cold air Cigarette smoke Perfumes URTIs Pets Tree or grass pollen Food Drugs (aspirin/ NSAIDs)
What type of variation in asthma might help determine the trigger ?
Daily- nocturnal/ early morning
Weekly- occupation, better at weekends/holidays
Annual- environmental triggers
What features of drug use are important to consider when diagnosing asthma ?
Current inhalers (technique, dosage, compliance)
Beta blockers
Aspirin
NSAIDS (Nonsteroidal anti-inflammatory drugs)
Effects of previous drugs/ inhalers
What aspects of social history are important to consider when diagnosing asthma ?
Smoking
Pets
Occupations past/present
Psychosocial aspects - Psychosocial profile can affect asthma
What common health conditions are important to consider when diagnosing asthma ?
Childhood asthma, bronchitis
Eczema
Hay-fever
What are some differential diagnosis when investigating asthma ?
Generalised airflow obstruction:
- COPD - bronchiectasis - cystic fibrosis
Localised airway obstruction (inspiratory stridor= large airways)
- tumour - foreign body
Cardiac
When is it unlikely to be asthma ?
Cervical lymphadenopathy
Stridor
Asymmetrical expansion
Dull percussion note (lobar collapse, effusion)
Crepitations - crackling or rattling sounds) (bronchiectasis, CF, alveolitis, LVF)
What are the two positive findings for asthma ?
Airflow obstruction
Variability and or reversibility of airflow obstruction
How can spirometry determine if someone has obstructed airways ?
FEV1 < 80% predicted
FEV1/FVC < 70%
What do FEV1 and FVC tell us respectively ?
Airway diameter
Lung Capacity
After confirmation of obstructed airways, what is your next step in the diagnosis of asthma ?
Full pulmonary function tests
Confirmation of reversibility with B2 agonists and steroids
What is reversibility to bronchodilators ?
Response to bronchodilator
Baseline, 15 mins post 400microg inhaled salbutamol
Baseline, 15 mins post neb 2.5-5mg salbutamol
Interpretation:
- significant reversibility-> FEV1> 200ml and FEV1 > 12% baseline
If airways are not obstructed what is your next step in diagnosis ?
Peak flow monitoring
Bronchial provocation with nitric oxide
What is the purpose of full pulmonary function testing ?
Excluding COPD/emphysema
What is reversibility to oral steroids ?
Response to oral corticosteroids (anti-inflammatory) Separates COPD from asthma 0.6mg/kg prednisolone 14 days Peak flow chart and meter Baseline and 2 weeks spirometry
When spirometry is normal why is it important to measure peak flow ?
Looking for variability in airflow obstruction
Lung function in clinic may(usually) be normal
What are the tests involved in the full pulmonary function testing ?
Lung volumes
Carbon monoxide gas transfer
What is the carbon monoxide gas transfer used to determine ?
Ability of gas transport across the alveoli, alveoli are unaffected in asthma it is only the airway that are affected
What are some specialist test to determine airway responsiveness ?
Methacholine
Histamine
Mannitol
Exhaled FeNO
How would you read the methacholine responsiveness ?
Reduction of FEV1 by over 20%
What is the effect of methacholine ?
Acts like acetylcholine to constrict airways
Nebulising the substance you think they are susceptible to can be useful too
What is the exhaled nitric oxide in an asthmatic patient compared to normal ?
Increase in nitric oxide
What are some other useful investigation ?
Chest X-ray:
- hyperinflated, hyperlucent
- no effusion, collapse, opacities, interstitial changes
Skin prick test:
- atopy status
Total and specific IgE:
- atopy status
Full blood count:
- eosinophilia (atopy)How can the severity of asthma be assessed ?
Moderate Severe Life threatening
Airway- PEFR 20-75 % PEFR 33-50% PEFR <33%
Breathing- RR <25 RR >25 Rest effort decreased, silent chest
Circulation- Pulse <110 Pulse > 110 Pulse <60,
Disability- Able to speak, Can’t complete grunting, exhaustion, confuse
complete sentences sentence in 1 breath
Exhange, gas- SaO2 > 92% SaO2 > 92% SaO2 <92%
(no need ABG) PaO2 > 8kPa PaO2 <8kPa
PaO2 >8kPa PaCO2 normal (4.6-6kPa)
How is fatal asthma assessed ?
Raised PaCO2
Need for mechanical ventilation
