Asthma Clinical Features Adults Flashcards
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 is atopy
Inherited tendency to develop IgE response to allergens
What are the genetic risk factors for asthma?
Strongest risk factor: personal, familial atopic tendency - Maternal atopy most influential (3x father)
What are the symptoms of Asthma?
Wheeze
Shortness of breath
Chest tightness
Cough
usually dry Sputum
What type of variation in asthma might help determine the trigger?
Daily variation- nocturnal/morning
Weekly variation- 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.
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
What is body mass index positively associated with?
Asthma
Wheezing
Airway hyperactivity
what is the hygiene hypothesis
- Reduced exposure to microbes/ microbial products•
- Children born on farms less likely to develop asthma
Microbial diversity also important in reducing risk of asthma and allergy
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 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
When is it unlikely to be asthma?
Finger clubbing
Stridor
Assymetrical expansion
Dull percussion note (lobar collapse, effusion)
Crepitations
Investigations
How can you determine if someone has obstructed airways?
Spirometry
FEV1 is less then 80% predicted
FEV1/FVC ratio<70%
Investigations
What do FEV1 and FVC tell us respectively?
Airway diameter
Lung Capacity
Investigations
After confirmation of obstructed airways, what is your next step in the diagnosis of asthma?
Full pulmonary function tests
Then confirmation of reversibility with B2 agonists
Investigations
If airways are not obstructed what is your next step in diagnosis?
Peak flow monitoring
Bronchial provocation with nitric oxide
Investigations
What is a bronchial provocation test?
Evaluates lung sensitivity
spirometry results compared before and after you inhale a spray
Shows changes in airway diameter
Spray is usually metahacholine.
Investigations
What is the purpose of full pulmonary funciton testing?
Excludes 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
only the airway is 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
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
Acute asthma
What are the moderate symptoms in acute asthma
Able to speak
HR< 110
RR<25
PEF 50-75%
Sa02> 92
Pa02>8kPa
acute asthma
What are the severe symptoms in acute asthma
Inability to complete sentences in one breath
HR>110
RR>25
PEF 33-50%
- SaO2 ≥ 92%
- PaO2 ≥ 8kPa
What are the life threatening symptoms of asthma
- Grunting
- Impaired consciousness,
confusion
- Bradycardia/ arrhythmia/ hypotension
- PEF < 33% predicted or best
- Cyanosis
- Silent chest
- Poor respiratory effort•
- SaO2 < 92% (definitely needs blood gas!)
- PaO2 < 8kPa
- PaCO2 normal (4.6 - 6.0kPa)
What are the near fatal symptoms of acute asthma
Raised PaC02