Adult Asthma Flashcards
What is important in defining asthma?
- Asthma is more of a concept than a definition
- Characterised by increased irritability (responsiveness), widespread narrowing of airways that changes in severity
Why do airways narrow when they become inflamed?
They narrow as they become thicker and mucous and debris falls into the airway
What is airway inflammation mediated by?
The immune system
What is the difference in diagnoses by sex?
Women are affected more than men
Give some examples of how asthma impacts peoples lives?
Some asthmatics are totally and very limited by asthma. They struggle with:
- Running
- Stairs
- DIY
- Gardening
- Sleeping
What is the impact of asthma on the NHS?
It is mainly dealt with in primary care but there are 67,000 admissions to hospital.
What is the change in prevalence linked to?
Changes in environment
What are the proven risk factors linked to asthma?
- Genetic- atopy
- Occupation
- Smoking
What are the 2 genetic associations with asthma that linkage studies have identified?
- Immune response genes: IL-4, IL-5, IgE
- Airway genes: ADAM33
How does genetics play a role in asthma?
- Inherited tendency to IgE response to allergens.
- Often accompanied by eczema, hay fever or food allergy
What form of atopy is most influential?
Maternal
What is the most common cause of occupational asthma?
Bakers who are exposed to flour and microbes
What are some examples of occupational asthma allergens?
- Isocyanates: twin pack paints
- Colophony: welding solder flux
- Laboratory animals: rodent urinary products
- Grains: wheat proteins, grain mites
- Enzymes: subtilisin, amylase
- Drugs: antibiotics, salbutamol
- Crustaceans: prawns, crabs
What does maternal smoking during pregnancy cause?
- Decreased FEV1
- Increased wheezy illness
- Increased airway responsiveness
- Increased asthma and severity
What is the grandmother effect?
If your grandmother smoked during pregnancy then you are 2.6X more likely to have asthma
What is the grandmother effect due to?
Mouse work suggests epigenetic modification of oocytes
What speculative risk factors are there?
-Obesity
-Diet
-Reduced exposure to microbes/microbial products
-Indoor pollution
-House dust mite
-Cat
Grass pollen
Speculative: What is an obese body mass index positively associated with?
- Asthma
- Wheezing
- Airway hyperreactivity
Speculative: Supplements in asthma?
There are some associations between supplements and asthma but they have not effect in established disease
Speculative: Exposure ot what microbial products is believed to reduce the likelihood of developing asthma?
- Endotoxin
- Glucans
- Extracapsular polysaccharide
Speculative: Exposure to what chemical products is thought to increase the likelihood of asthma?
- Volatile organic compounds
- Formaldehyde
- Fragrances
Speculative: Who is at most risk of developing asthma related to indoor pollution?
- Cleaners
- Mothers using sprays during pregnancy increases the chances of the child having asthma
Speculative: Why is it thought that house dust mites increase the risk of asthma?
- They thrive in warm, humid environments
- They release 200X own weight in droppings
- The droppings contain protease which is an allergen
Speculative: Why does sensitisation to cats present a major problem?
There is constant exposure as cat hairs spread to peoples clothes and surfaces
What can include localised airway obstruction?
- Inspiratory stridor
- Tumour
- Foreign body
What can be included in generalised airflow obstruction?
- Asthma (reversible AFO)
- COPD (irreversible AFO)
- Bronchiectasis
- Bronchiolitis
- Cystic Fibrosis
What common respiratory symptoms are often reported with asthma?
- Wheeze
- Short of breath (dyspnoea), severity
- Chest tightness (pain)
- Cough, paroxysmal, usually dry
- Sputum (occasional)
What are common triggers for asthma/
- Exercise
- Cold air
- Smoke
- Perfume
- URTI’s
- Pets
- Trees
- Grass pollen
- Food
- Aspirin
What variations exist in asthma?
- Daily variation (nocturnal/early morning)
- Weekly variation ( in occupational, better at weekends and holidays)
- Annual variation (environmental allergens)
When taking a history, what is important to note?
- PMH: childhood asthma, bronchitis, eczema, hayfever
- Drugs: current inhalers, B-blockers, aspirin, NSAIDS, previous inhalers
- FMH: atopic disease
- PSH: smoking, pets, occupations past/present, psychological aspects
What is usually unhelpful in the clinical setting?
- Breathless on exertion
- Hyperextended chest
- Polyphonic wheezes
What would suggest it wasn’t asthma?
- Clubbing
- Cervical lymphadenopathy
- Stridor
- Asymmetrical expansion
- Dull percussion nota
- Crepitations
In essential investigations, what are you looking for?
- Airflow obstruction
- Variability and/or reversibility of airflow obstruction
What is spirometry used to determine?
If there is airway obstruction
If there is airway obstruction, what is the next step?
Full pulmonary function testing
What can be excluded after full pulmonary function testing?
COPD/ emphysema
In pulmonary function testing what can lung volumes tell us?
- Helium dilution test can indicate gas trapping:
- Increased residual volume
- Increased total lung capacity
In pulmonary function testing what occurs during carbon monoxide gas transfer?
Transfer of CO to Hb across alveoli tells you how well the alveoli are working
If there is airway obstruction, what should be done after pulmonary function testing?
Reversibility to bronchodilator
Interpretation of reversibility to bronchodilator…
- There should be significant reversibility
- No bronchoconstriction= no reversibility
- Severe bronchoconstriction= no reversibility
Why is testing the reversibility to oral corticosteroids useful?
Separates COPD from asthma
How should reversibility to oral corticosteroids be tested?
- 0.6mg/kg of Prednisolone, 14 days
- Peak flow chart and meter
- Baseline and 2 week spirometry
What does normal spirometry suggest?
Variability of airflow obstruction
What might be seen in and asthmatics spirometry?
- Morning/nocturnal dips
- Decline over weeks/days
- Variability >20%
How is occupational asthma diagnosed?
-Serial peak flow readings
-2 hourly best 5 day minimum
2 pairs of exposed/ unexposed periods
What specialist investigations can be carried out?
- Airway responsiveness to methacholine/histamine
- Exhaled nitric oxide
How is the level of exhaled nitric oxide useful?
Asthmatics usually have elevated levels of nitric oxide expired
What other useful investigations are there?
- Chest X-ray (hyperinflated/ hyperlucent)
- Skin prick testing (atopic status)
- Total and specific IgE (atopic status)
- Full blood count (eosinophilia )
- Useful but not diagnostic
What is important to note when assessing severity of asthma?
- Ability to speak
- Heart rate
- Respiratory rate
- PEF
- Oxygen saturation/ arterial blood gases
What is suggestive of moderate asthma?
- Abel to speak in complete sentences
- HR<110
- RR<25
- PEF 50-75% predicted or best
- SaO2 > 92%
- PaO2>8kPa
What is suggestive of sever asthma?
- Unable to speak in complete sentences
- HR>110
- RR>25
- PEF 33-50% predicted or best
- SaO2 >92%
- PaO2>8kPa
What is suggestive of life threatening asthma?
- Grunting
- Impaired consciousness, confusion, exhaustion
- HR>130 or bradycardic
- Hypoventilating
- PEF<33% predicted or best
- Cyanosis
- SaO2<92%
- PaO2<8kPa
- PaCO2 normal
What is suggestive of near fatal asthma?
Raised PaCO2
