Asthma Clinical Features, Adults and Children Flashcards
What is asthma characterised by?
Increased responsiveness of trachea and bronchi to various stimuli and manifested by widespread narrowing of airways.
How can asthma change in severity?
Spontaneously or as a result of therapy
What causes the airways to become inflamed?
The immune system
What does the increased airway reactivity cause?
Airway narrowing - resulting spontaneously or from stimuli
What is the prevalence of asthma?
Children 10 - 15% M > F
Adults 5 - 10% F > M
What are the genetic risk factors for asthma?
Atopy
- Inherited tendency to IgE response to allergens
Asthma, eczema, hayfever, food allergy Markers, skin prick tests, IgE
Strongest risk factor: personal, familial atopic tendency - Maternal atopy most influential (3x father)
What allergens can occupation expose you to?
Isocyanates (paints)
Colophony (welding solder flux)
Laboratry Animals
Grains
Enzymes
Drugs
Crustaceans
What are the symptoms of Asthma?
Wheeze Shortness of breath Chest tightness Cough paroxysmal, usually dry Sputum
What are typical triggers?
Exercise, cold air, smoke, perfume, URTI’s, pets, tree, grass pollen, food, aspirin
What type of variation in asthma might help determine the trigger?
Daily Weekly - Occupation, weekends? Holidays? Annual Variation (environmental allergens)
What are essential investigation for asthma diagnosis?
Airflow obstruction Variability and reversibility of airflow obstruction
What is the effect of maternal smoking on FEV1?
FEV1 ia reduced
What is the effect of maternal smoking on Wheezy illness, airway responsiveness, asthma and severity?
All increase
What is known as the Grandmother effect?
Grandchildren are far more likely to suffer from asthma if their grandmothers smoked while pregnant.
Mouse work suggests epigenetic modification of oöcytes
What are the three proven risk factors?
Smoking, genetic and occupation
What are possible risk factors for asthma?
Obesity, diet, reduced exposure to microbes/microbial products, indoor pollution, environmental allergens (house dust mite, cat, grass pollen)
What is body mass index positively associated with?
Asthma
Wheezing
Airway hyperactivity
Which diet substances affect risk of asthma?
Decrease in anti oxidants and N-3 polyunsaturated fatty acids = risk factor
Increase in N-6 polyunsaturated fatty aids = risk factor
Too much or too little vitamin D
Where might a child be born who has a smaller risk of developing asthma?
Farms - increased exposure to microbes and microbial products on the farm
Give an example of microbial products
Endotoxin, glucans, extrascapular polysaccharide
Microbial diversity also important in redusing risk of asthma and allergy
Which indoor cleaning products have an increased risk of causing cancer?
Volatile organic compounds
Formaldehyde
Fragrances
What feature of the dust mite is allergenic?
Protease in droppings
What influence does affluence have on allergens?
Increases the likelihood of sensitisation to local allergens
What is the most important consideration when making an asthma diagnosis?
HISTORY
What are the symptoms of asthma?
WHEEZE
Dyspnoea
Chest tightness
Cough, usually dry
Sputum
What are the common triggers for asthmatics?
Exercise
Cold air
Smoke
Perfume
URTI’s
Pets
Tree
Grass
Pollen
Food
Aspirin
What type of time variation exists in asthmatics?
Daily variation
Weekly variation (occupation will usually be the cause - weekends are when the employee isn’t working)
Annual variation (environmental allergens)
What common health conditions are important to consider when diagnosing asthma?
Childhood asthma, bronchitis
eczema
hayfever
Hayfever and eczema are other atopic conditions
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
FMH
Atopic disease
What aspects of socail history are important to consider when diagnosing asthma?
Smoking
Pets
Occupations past/present
Psychosocial aspects - Psychosocial profile can affect asthma
When is it unlikely to be asthma?
Cervical lymphadenopathy
Stridor
Assymetrical 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 you determine if someone has obstructed airways?
FEV1 is less then 80% predicted
FEV1/FVC ratio<70%
What do FEV1 and FVC tell us respectively?
Airway diameter
Lung Capacity
After confirmation of obstructed airways, what is your next steo in the diagnosis of asthma?
Full pulmonarty funciton tests, confirmation of reversibility with B2 agonists and steroids
If airways are not obstructed what is your next step in diagnosis?
Peak flow monitoring
Bronchial provocation with notric oxide
What is a bronchial provocation test?
Evaluates how sensitive the airways in your lungs are. The spirometry results are compared before and after you inhale a spray to see what changes there are in your breathing. Spray is usually metyhacholine.
What is the purpose of full pulmonary funciton testing?
Excluding COPD and emphysema
What are the tests involved in the full pulmonary funciton testing?
Lung volumes
Carbon monoxide gas transfer
What is gas trapping?
Abnormal retention of air in the lungs where it is difficult to exhale completely
Observed in obstructive lung diseases such as asthma, bronchiolitis obliterans syndrome and chronic obstructive pulmonary diseases such as emphysema and chronic bronchitis.
How is lung residual volume measured of the lungs?
Helium dilution technique
The patient inhales breaths of helium and oxygen in a closed system. Concentration of helium will decrease as it diffuses into all areas of the lung. The amount of concentration reduction it indicative of the residual capacity
What is the residual volume and total lung capacity of a patient who is asthmatic?
Increased residual volume
Increased total lung capacity
RV/TLC > 30%
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.
When will there be no response to bronchodilator?
When there is no bronchoconstriction or severe bronchoconstriction
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 test is likely to increase use of according to NICE?
Exhaled nitric oxide tests
How would you read the methacholine responsiveness?
Reduction of FEV1 by over 20%
What is the effect of methachoine?
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 the other useful investigations?
Chest X-ray - Hyperinflated, hyperlucent (lung or portion thereof is less dense than normal, as from air trapping by a bronchial foreign body)
Skin prick testing (atopic status)
Total and specific IgE (atopic status)
Full blood count
Eosinophilia (atopy
What are the most important considerations when diagnosing acute asthma?
Objective > subjective
Ability to speak
Heart rate
Respiratory rate
PEF (peal expiratory flow)
Oxygen saturation / arterial blood gases
No need for pulsus paradoxus (also paradoxic pulse or paradoxical pulse, is an abnormally large decrease in systolic blood pressure and pulse wave amplitude during inspiration)
