8. Asthma: clinical features Flashcards
What is the definition of asthma?
Disease characterised by an increased responsiveness of the trachea and bronchi to various stimuli and manifested by a widespread NARROWING of airways that changes severity either spontaneously or as a result of therapy
Why is asthma difficult to diagnose at times?
-There is no diagnostic test or specific symptom
How is asthma diagnosis? (what is used?)
Diagnosis made on patterns in tests and symptoms
Is there an alveolar component to asthma?
No- just the airways (trachea, bronchi)
What is the main difference between COPD and asthma?
- COPD has constantly constricted airways (irreversible)
- Asthma can have better and worse symptoms (comes and goes) which makes narrowing of airways reversible and variable
What is airway inflammation mediated by?
The immune system
What 2 things can airway inflammation lead to?
- widespread narrowing of airways
2. increased airway reactivity (leading to airway narrowing)
In what 2 ways can airway narrowing/constriction happen?
- spontaneously (waking up with closed airways)
2. stimuli (due to allergen like pollen or exposure to a stimulant)
What do inflamed airways produce?
Increased mucus production (for debris) leading to irritability
What is the prevalence of asthma in children? (%)
10-15%
Is asthma more prevalent in males or females in children?
males
What is the prevalence of asthma in adults? (%)
5-10%
Is asthma more prevalent in males or females in adults?
females
How many people are receiving asthma treatment in UK?
~5.4 million (1.1 million children and 4.3 million adults)
How many asthma related deaths are there in UK every year?
~1000 per year (most are >60 years and smokers, usually COPD related)
What are the 3 top activities which are the most limited by asthma?
running, sport and stairs
Roughly how many asthma admissions are there per year?
67,000 admissions (220,000 bed days)
Roughly how many asthma GP consultations are there?
approx. 4.1 million
How much does treating patients with asthma cost the NHS annually?
~£2.3 million (only 2% of NHS budget)
What are 3 top PROVEN factors for asthma?
- genetics (atopy)
- occupation
- smoking
Define atopy.
Inherited tendency to IgE response to allergens (genetic inheritance predisposition towards developing an allergic hypersensitivity)
What 4 common conditions can be caused by atopy risk factor?
- asthma
- eczema
- hayfever
- food allergy
What methods are used to test for atopy related asthma (or other allergies)?
- IgE testing
- skin pick tests
- markers
Out of all 3 risk factors for asthma, what is the strongest risk factor?
personal, familial atopic tendency
Which copy, maternal or paternal is most influential?
Maternal (3x stronger than paternal)
-mother has bigger genetic effect on the child than father
What are 2 groups of genetic associations related to asthma? And what are their examples?
- immune response genes (IL-4, IL-5, IgE)
2. airway genes (ADAM33)
Occupation contributes what percentage towards adult onset asthma?
10-15% (interaction with smoking and atopy)
What are 7 common agents which can lead to asthma in occupation circumstances? (GLEDDIC)
- isocyanates
- colophony
- laboratory animals
- grains
- enzymes
- drugs
- crustaceans
GLEDICC
What is an example of isocyanates that can cause asthma?
twin pack paints
What is an example of colophony that can cause asthma?
welding solder flux (cleaning agent)
What is an example of lab animals features that can cause asthma?
rodent urinary proteins
What are examples of grains that can cause asthma? (2)
- wheat proteins
- grain mites
What are examples of enzymes that cause asthma?
- subtilisin
- amylase
What are examples of drugs that can cause asthma?
- antibiotics
- salbutamol
What are examples of crustaceans that can cause asthma?
-prawns
-crabs
(fish and shellfish proteins due to inhalation)
What does maternal smoking during pregnancy decrease in the unborn child?(1)
Its FEV1
What does maternal smoking during pregnancy increase in the unborn child? (4)
- wheezy illness
- airway responsiveness
- asthma
- severity of disease
Describe the increased risk of the child developing asthma in percentages if;
- mother smoked
- grandmother smoked
- both mother and grandmother smoked during pregnancy
- mother: increased risk of 50%
- grandmother: increased risk of 100%
- mother AND grandmother: increased risk of 150%
“the grandmother effect”
What causes the “grandmother effect”
epigenetic modification in oocytes
What is a patient’s BMI positively associated with in terms of airway conditions? (3)
- asthma
- wheezing
- airway hyperactivity
What dietary diet-related foods are associated with a possible risk factor for developing asthma? (4)
- decrease in antioxidants
- decrease in n-3 polyunsaturated fatty acids
- increase in n-6 polyunsaturated fatty acids
- increase/decrease of vitamin D
What dietary 3 vitamins and a substance decrease are associated with a decrease in FEV1?
Decrease in:
- vitamins E,C,D
- Beta-carotene
What dietary 2 vitamins and 2 other substance decrease are associates with an increased wheeze?
Decrease in:
- vitamins E and C
- fruit
- margarine
What dietary vitamin and 3 other substances decrease are associated with increased asthma?
Decrease in:
- vitamin D
- selanium
- fast food
- margarine
What 2 dietary substances increase are associated with a decreased wheeze and asthma?
Increase in:
- oily fish consumption
- butter
Is supplementation of dietary supplements and substances in established disease effective?
No; it does not change the state of the disease
Children born on farms are less likely to develop asthma due to exposure to which microbes/microbial products on farms? (3)
- endotoxin
- glucans
- extracapsular polysaccharide
(increase microbial diversity in individuals)
What chemical household products possibly increase the risk of asthma? (4)
- volatile organic compounds ( VOCs released by plastics)
- formaldehyde
- fragrances
- cleaning agents
Are mothers who use sprays during pregnancy at increased risk of their child developing asthma?
Yes
What are 5 POSSIBLE risk factors for asthma?
- obesity
- diet
- indoor pollution
- microbial products
- environmental allergens
What are 3 common environmental allergens which may lead to asthma?
- house dust mite (allergen is protease droppings and found in pillows/bed)
- cats (universal exposure to allergen, but early exposure maybe protective)
- grass pollen (timothy grass)
Is there evidence to suggest that early exposure to allergens is effective?
Yes; it can be beneficial, as there is a link between affluence increasing the likelihood of sensitisation to allergens because not enough exposure occurred in early life.
What are 3 other possible causes of wheezing?( that is not asthma)
- airway obstruction
- inspiratory stridor tumour (causing harsh vibration sound)
- foreign body
What 5 medical conditions cause wheezing?
differential diagnosis
- asthma (reversible AFO)
- COPD (irreversible AFO)
- bronchiectasis
- bronchiolitis
- cystic fibrosis
What is the most important aspect to consider when making a diagnosis of asthma?
Patient’s HISTORY (most important)
What symptoms are common for asthma diagnosis?
- wheezing
- short of breath (dyspnoea) and severity
- chest tightness (pain)
- cough (paroxysmal/spasm/seizure, usually dry)
- sputum (occasional)
Since asthma symptoms are very generic to most respiratory diseases, what do doctors look for specifically among these symptoms?
the variability between them (symptoms per say don’t define asthma)
What are possible triggers of asthma patient symptoms? (9)
- exercise
- cold air
- smoke
- perfume
- URTIs (upper resp. tract infection)
- pets
- grass pollen and trees
- aspirin/ drugs
- food
What is meant by daily variation in symptoms?
do symptoms becomes better/worse during nocturnal or morning hours
(asthma symptoms usually worst early in the morning or late at night)
What is meant by weekly variation in symptoms?
- Can be due to occupation (better at weekends/ holidays?)
- due to patients being exposed to specific allergens in particular jobs
What is meant by annual variation?
any environmental allergens (due to season e.g. spring when there is more pollen)
What 3 past medical history aspects need to be considered when diagnosing asthma?
- childhood asthma or bronchitis
- eczema
- hayfever
What drugs need to be considered when diagnosing asthma? (5)
- current inhalers (NOT puffs), check technique and compliance
- Beta blockers
- aspirin
- NSAIDs (non-steroidal anti-inflammatory drugs)
- effects of previous drugs/inhalers
What family medical history aspect needs to be considered when diagnosing asthma? (1)
atopic disease(clinical syndromes defined by signs and symptoms; asthma, eczema or rhino conjunctivitis)
What past social history aspects need to be considered when diagnosing asthma?(4)
- smoking
- pets
- occupation past/present (what job entails)
- psychological aspects (stress)
What 3 signs are unhelpful on examination in the clinic?
- breathless on exertion
- hyperexpanded chest
- polyphonic wheezes
Is cracking associated with asthma?
NO; only wheezing!
(Crackling suggests infection or inflammation of bronchi, bronchioles or alveoli. Crackles that don’t clear after cough may indicate fluid or pulmonary oedema due to heart failure, pulmonary fibrosis or acute respiratory distress syndrome)
On examination, what signs indicate there is NO asthma? (5)
- clubbing
- cervical lymphadenopathy
- stridor
- asymmetrical expansion (because it affects both lungs)
- dull percussion note (lobar collapse, effusion/fluid escape
- crepitations/crackling (bronchiectasis, cystic fibrosis, alveolitis, left ventricular failure (LVF))
What technique is used to demonstrate obstruction?
spirometry (measures volume over time of FEV1 and FVC)
Medical investigations look for the evidence of which 2 things when looking for asthma?
- airflow obstruction
2. variability and/or reversibility of airflow obstruction
What must the ratio of FEV1:FVC be to indicate obstruction in airways? (e.g. asthma)
usually ratio <70%
FEV1 <80%
Why can asthmatics have a normal FEV1:FVC ratio?
Because asthma is VARIABLE so ratio can be normal one time of the day and abnormal a few hours later
What are the asthma diagnostic steps if the spirometry reading is normal?
- normal reading
- peak flow monitoring
- bronchial provocation (nitric oxide)
What are the asthma diagnostic steps if the spirometry reading is obstructed (FEV1:FVC ratio<70% and FEV1<80% predicted)
- obstructed reading
- full pulmonary function tested
- reversibility by: B2 agonists and steroids
What does full pulmonary function testing effectively exclude?
emphysema/ COPD (has different patterns for distinguishing between the two)
What two diagnostic methods can be used to test full pulmonary function?
- lung volumes (helium dilution)
2. carbon monoxide transfer (transfer of CO to Hb across alveoli)
What does helium dilution involve? (tests lung volume)
- helium dilutes with air in the lungs
- involves gas trapping
- increases residual volume and total lung capacity
- RV/TLC >30%
What does CO gas transfer involve?
- CO is breathed in and binds to Hb
- tells clinicians how well alveoli are working
- there is no tissue destruction
- there is no alveolar transfer in asthma; so if there is a fault, tis means it’s not asthma
- TLCO and KCO measured (CO transport factors)
What are the 2 types of reversible treatments?
- B2 agonist (bronchodilator)
2. corticosteroids
What are the types of salbutamol (bronchodilator, B2 agonist) administration?
- inhalation
- nebuliser (liquid)
What is the response to inhaled salbutamol?
- baseline/initially 15 minutes post 400micrograms
What is the response to nebulising salbutamol?
-baseline/initially 15 minutes post 2.5-5mg
What are the reversibility changes for FEV1 once bronchodilators like salbutamol are administered?
FEV1>200ml
FEV1>15% baseline
When is there no reversibility in the airways if bronchodilators like salbutamol are administered?
- when there is no bronchoconstriction
- when there is severe bronchoconstriction
What is corticosteroids’ main property?
-It’s anti-inflammatory
What can corticosteroids distinguish asthma from?
COPD; as in asthma the airways will open up while in COPD they will not
What is an example of a commonly used oral corticosteroid, what dose is administered and over how long?
- Prednisolone
- 0.6mg/kg
- over 14 days
How is the effectiveness of Prednisolone (corticosteroid) measured which is used to treat asthma?
- using peak flow chart and meter (peak flow increases when steroids taken as it’s low in asthmatics)
- baseline and 2 week spirometry
If spirometry comes out normal while diagnosing an asthmatic patient, what is the next diagnostic step?
Peak flow monitoring; watching for variability in airflow obstruction (because lung function in clinic is usually normal)
What is used to monitor peak flow for variability in airflow obstruction and how often and for how long?
- A peak flow meter
- twice daily
- 2 weeks
What analysis subjective points confirm an asthma diagnosis after using peak flow meter?
- morning/ nocturnal dips
- decline over weeks/days
- big variability >20% (highest-lowest /highest, as inconsistence suggests asthma)
Does peak flow change much in non-asthmatics?
No, it hardly changes
What are the diagnostic steps for diagnosing occupational asthma? (5)
- suspicion from work related symptoms and working with recognised occupational sensitiser (irritates airways)
- serial peak flow readings
- antibodies tested
- bronchial challenge (new agent)
- positive response to colophony
What are the steps for serial peak flow readings for diagnosis of occupational asthma? (OASYS peak flow chart used)
- taken every 2 hours best for 5 days minimum (usually for 2 weeks)
- 2 pairs of exposed/unexposed periods (a least)
- pattern should appear of when airways work at their worst and best
What are the 2 types of specialist investigations used to diagnose asthma in patients with a normal spirometry reading?
- airway responsiveness to methacholine/histamine (inhaled)
- exhaled nitric oxide (NO)
What is the approximate cumulative dose of methacholine in non-asthmatics during FEV1?
around 200micrograms (smaller value for asthmatics as responsiveness would be better)
What is used if there is no positive response to colophony in diagnosing occupational asthma? (2)
- methyl ester
- maleic ester
What compound do asthmatics produce more of in their cells? (have higher levels)
Nitric oxide (exhaled nitric oxide= ENO)
What are useful investigations to do in patients we suspect of asthma? (4)
- chest x ray
- skin prick testing (atopic status)
- total and specific IgE (atopic status)
- full blood count (eosinophilia; atopy)
What does a chest x ray look out for in asthmatic patients? (6)
- hyperinflated lung field
- hyperlucent (less dense lung)
- no effusion
- collapse
- opacities (lack of transparency)
- interstitial changes
In what circumstances is IgE testing usually done in asthmatic patients?
when asthma is triggered by a specific stimuli
Life threatening asthma may not include distress, but what signs are important in detecting it?
1.ability to speak (check if breaths need to be taken during speech which suggests big problem)
2. heart rate
3.respiratory rate
4.PEF (peak expiratory flow)
5. Oxygen saturation/arterial blood gases
NO NEED FOR PULSUS PARADOXUS (large fall in systolic blood pressure and pulse wave amplitude during inspiration)
What are signs of acute asthma in terms of lab statistics?
- increasing symptoms but no severe features
- Heart Rate<110
- Respiratory Rate<25
- peak expiratory flow 50-75% predicted or best
- SaO2>92% (saturation of O2)
- PaO2>8kPa
What are the signs of severe asthma in terms of lab statistics?
Any one from…
- unable to speak or complete sentences
- heart rate>110
- respiratory rate>25
- peak expiratory flow 33-50% predicted or best
- SaO2>92% (saturation of O2)
- PaO2?8kPa
What are the signs of life-threatening asthma?
- grunting
- impaired consciousness, confusion or exhaustion
- Heart rate>130 or bradycardic (<60)
- hypoventilating
- Peak expiratory flow <33% predicted or best
- cyanosis (dicolouration of skin due to poor circulation)
- SaO2<92%
- PaO2<8kPa
- PaCO2 normal (4.6-6kPA)
When is asthma nearly fatal?
Raised PaCO2 (leading to patient feeling tired and suffering from cardiac arrest eventually)
How would asthma symptoms be generally described and diagnosed?
- variable
- intermittent (come and go, not continuous)
- exclude other causes of wheeze and dyspnoea
- demonstrate airflow obstruction (in peak flow charts)
- reversibility to bronchodilators or steroids (try and see if it works, if it doesn’t then it’s not asthma)
What is nearly always used to assess ACUTELY unwell asthmatics?
objective parameters
If in doubt, what should be done to assess an asthmatic’s condition?
blood gas
