Asthma Flashcards
What is Asthma?
chronic respiratory condition where the airways are hyper-responsive and become narrow due to inflammation and tightening of smooth muscle
How many people are diagnosed with asthma in the UK?
8 million people in the UK, higher incidence in children
What is the most common industrial lung disease and accounts for 15% of adult onset asthma?
occupational asthma
What is the aetiology of asthma
family history of atopic disease
tobacco or smoke exposure
premature birth and low birth weight
respiratory infection in infancy
social deprivation
obesity
pollution or workplace exposure
What is the atopic triad?
asthma
allergic rhinits
eczema
What are the clinical features of asthma?
cough
polyphonic wheeze (loud, musical and continuous, in expiration and inspiration, heard over anterior, posterior and lateral chest wall)
chest tightness
shortness of breath
How is Asthma diagnosed?
fractional exhaled nitric oxide (FeNO) testing
spirometry
bronchodilator reversibility (BDR)
peak expiratory flow (PEF) readings
direct bronchial challenge testing with histamine or methacholine.
What does FeNO do?
measures level of nitric oxide when the patient breathes out. Nitric oxide is produced when the airways are inflamed so increase in asthma
What is key about asthma symptoms?
episodic
diurnal variation
occur in response to triggers
symptoms are worse at night and in the early morning
occur in response to exercise, allergen exposure, and cold air
occur after taking non-steroidal anti-inflammatory drugs or beta-blockers
occur in the absence of an upper respiratory tract infection
What are the levels of FeNO in children aged 5-16 years old?
35 ppb in children
What are the levels of FeNO in adults (above 17 years old) with asthma?
above 40 parts per billion
What does spirometry measure?
Forced vital capacity: volume of air blow out in one breath forcibly
Forced expiratory volume: volume of air blow out in one second forcibly
used to calculate FEV1/FVC: percentage blown out in one second
What drug do you administer in bronchodilator reversibility testing?
Salbutamol 400 micrograms and then repeat the spirometry test after 15 minutes
if spirometry improves, this SUGGESTS a diagnosis of asthma
if spirometry stays the same, this SUGGESTS a fixed obstructive respiratory pathology like COPD
partial reversibility=mixed lung pathology
What does this show?
A normal pattern
What does this show?
An obstructive pattern
Reduced FEV1 (<80% of the predicted normal)
Reduced FVC (but to a lesser extent than FEV1)
FEV1/FVC ratio reduced (<0.7)
What does this show?
A restrictive pattern
Reduced FEV1 (<80% of the predicted normal)
Reduced FVC (<80% of the predicted normal)
FEV1/FVC ratio normal (>0.7)
Why is peak flow used?
measures how fast a patient can breathe out after a full breath in. score is lower if the airways are inflamed. used to diagnose asthma and MONITOR response to asthma treatment
