Clinical features of asthma Flashcards
What is the definition of asthma?
A disease characterised by an increased responsiveness of the trachea and bronchi to various stimuli and manifested by a widespread narrowing of airways that changes in severity either spontaneously or as a result of therapy.
What 2 paths can airway inflammation mediated by the immune system go down?
- Widespread narrowing of airways
- Increased airway reactivity > Airway narrowing > Spontaneously or Stimuli.
Is asthma more common in males or females in children?
More common in males
Is asthma more common in males or females in adults?
More common in females
What are proven risk factors for asthma?
- Genetic: Atopy
- Occupation
- Smoking
Features of Atopy in asthma
- Inherited tendency to IgE response to allergens.
- Strongest risk factor: personal, familial atopic tendency, Maternal atopy most influential.
Which two groups of genetic association genes are linked to asthma?
- Immune response genes: IL-4, IL-5, IgE
2. airway genes: ADAM33
What changes can maternal during pregnancy cause?
- Decreased FEV1
- Wheezy illness
- Increased responsiveness
- Increased asthma and severity
What are possible risk factors for asthma?
- Obesity
- Diet
- Reduced exposure to microbes/microbial products.
- Indoor pollution: chemical household products
Clinical aspects of asthma
- It is a reversible obstruction
- Daily symptom variability
- Family history
- No smoking
- Allergy, rhinitis, eczema maybe.
What is the most important aspect when diagnosing asthma?
HISTORY
Symptoms: wheeze, short of breath (dyspnoea), severity chest tightness (pain), cough, paroxysmal, usually dry sputum.
What are evidence of variable symptoms?
- Triggers :exercise, cold air, smoke, perfume, URTI’s, pets, tree, grass pollen, food, aspirin.
- Daily/ weekly/ Annually variation
- PMH
- Drugs
- FMH
- PSH
What examination findings is usually unhelpful in clinic?
- Breathless on exertion
- Hyperexpanded chest
- Polyphonic wheezes
What findings mean its probably not asthma?
- Clubbing, cervical lymphadenopathy
- Stridor- hard inspiratory wheeze, blocking of trachea or proximal bronchi.
- Assymetrical expansion
- Dull percussion note
- Crepitations
What evidence are you looking for in an essential investigation for asthma?
- Airflow obstruction
- Variability and/or reversibility of airflow obstruction
Examples of essential investigations for asthma?
- If obstructed: Full pulmonary function testing
- Reversibility to bronchodilator
- Reversibility to oral corticosteroids
- If normal spirometry: variability to airflow obstruction.
Features of full pulmonary function testing
- Effectively excluding COPD/emphysema
- Lung volumes (helium dilution)
- Carbon monoxide gas transfer (transfer of CO to Hb across alveoli)
Features of reversibility to bronchodilator
- Response to bronchodilator
- Significant reversibility: FEV1>200ml & FEV1>15% baseline
- no bronchoconstriction, no reversibility
- severe bronchoconstriction, no reversibility
Features of reversibility to corticosteroids
- Response to corticosteroids (anti-inflammatory)
- Useful if obstructed, reversibility, variability.
- Separates COPD from asthma
Features of airflow obstruction
Analysis subjective:
- morning/nocturnal dips
- decline over weeks/days
- variability > 20%
Diagnosis of occupational asthma
- Suspicion from work related symptoms.
- Working with recognised occupational sensitiser
- Confirmation- serial peak flow readings, antibodies, bronchial challenge, positive response to colophony.
Specialist investigations for asthma
- Airways responsiveness to methacholine/histamine.
- Exhaled nitric oxide (NO)
Give substances that you know will cause bronchoconstriction
Useful investigations for asthma
- Chest X-Ray
- Skin prick testing (atopic status)
- Total and specific IgE (atopic status)
- Full blood count
Moderate symptoms of asthma
- Able to speak, complete sentences
- HR <110
- RR <25
- PEF 50 - 75% predicted or best
- SaO2 > 92% (no need for ABG)
- PaO2 > 8kPa
Severe symptoms of asthma
- Unable to speak, unable to complete sentences
- HR >110
- RR >25
- PEF 33 - 50% predicted or best
- SaO2 > 92%
- PaO2 > 8kPa
Life threatening symptoms of asthma
- Grunting
- Impaired consciousness, confusion, exhaustion
- HR >130, or bradycardic
- Hypoventilating
- PEF < 33% predicted or best PEF=peak flow
- Cyanosis
- SaO2 < 92%
- PaO2 < 8kPa
- PaCO2 normal (4.6 - 6.0kPa)
Life threatening symptoms of asthma
Same as life threatening symptoms but
Raised PaCO2
Features of asthma
- Literally “panting”
- Chronic
- Wheeze, cough and SOB
- Multiple triggers: URTI, exercise, allergen, cold weather etc.
- Variable/reversible
- Responds to asthma Rx
- No uniform definition
What are some of the multiple hits that lead to asthma?
- Genes
- Inherently abnormal lungs
- Early onset atopy
- Later exposures: Rhinovirus, exercise, smoking.
What is the key information used to diagnose asthma?
History of patient
Methods for objective testing for asthma in children
- Spirometry
- Bronchodilator reversibility
- FeNO
Do not diagnose base asthma only based on spirometry and BDR, make sure you check FeNO
Features of wheeze in asthma
- A “must have”
- Cough variant asthma does not exist
- Cough predominant asthma not uncommon
Features of Atopy
- Does not “cause” asthma: Atopy and asthma secondary to same process,
URTI primary precipitant - Personal history: eczema, hayfever, food allergies.
- Family history
What are the ideal symptoms/reactions which would allow the diagnosis of asthma?
- Wheeze, shortness of breath at rest
- Multi trigger
- Atopy
- Parental asthma
- Responds to treatment
Features of small print for differential diagnosis for asthma
- Foreign body
- Cystic fibrosis
- Immune deficiency
- Ciliary dyskinesia
- Tracheo-bronchomalacia
- Aspiration
Cystic fibrosis, immune deficiency and ciliary dyskinesia are all secretions.
What is used to treat infrequent episodic wheeze with a cold
Salbutamol
What should you NOT use to treat infrequent episodic wheeze with a cold
- Oral steroids in hospital
- Oral steroids at home
- Short “burst” at home
- Short “burst” of LTRA
When could it be infection and not asthma
- Under 18 months old, most likely infection.
- Over 5 years, most likely asthma.
HOWEVER, if it sounds like asthma and responds to asthma it is asthma regardless of age!
Features of bronchitis
- Common
- Loose rattly cough
- Noisy breathing
- Child is very well
- Chest free of wheeze/creps
- Self-limiting
Mechanisms of bacterial bronchitis
- Disturbed mucociliary clearance: RSV/adenovirus/rhinovirus, haemophilus culture medium, >4 week recovery
- Infection secondary
- Lack of social inhibition
Features of Pertussis
- This is common
- Vaccination reduces risk
- “coughing fits”
- Vomiting, colour change, petechiae
When is it not asthma in preschool children
Cough and noisy breathing
- Bronchitis (2-3 year old, wet cough)
- Tracheomalacia (Life long loud cough)
- Small print
- Pertussis
When is it not asthma in school aged children?
Cough and noisy breathing
- Habitual cough (8-12 year old, single loud cough)
- Dysfunctional breathing
- Vocal cord dysfunction
- Pertussis (any age, fits, vomit, haematoma)
Is there a test for asthma in children?
NO
- There is no test for asthma in children.
- There is no lower age limit for diagnosing asthma.
