Asthma Flashcards
Definition of asthma
A chronic respiratory condition associated with airway inflammation and hyper-responsiveness. It is a heterogenous condition with varying underlying disease processes, clinical course and response to treatment.
Characteristic symptoms of asthma
Cough, wheeze, chest tightness and SOB. Additionally there will be variable expiratory airflow limitation, which can vary over time and intensity.
What factors can trigger symptoms
Exercise, allergen, and viral exposure
Prevalence and peak age of onset of asthma. gender distribution.
- Affects around 11.6% of children aged 6 to 7 years
- In early childhood, asthma incidence is higher in boys than in girls
- It is the most common chronic childhood respiratory
What complicates diagnosis of asthma in young children
Approximately half of all children wheeze at some time during the first 3 years of life (have small airways so should be careful to diagnose asthma)
What are the THREE patterns of wheezing
- Viral episodic wheeze: wheeze developed in response to viral infections.
- Multiple trigger wheeze: in response to multiple triggers- more likely to develop into asthma over time
- Asthma
Pathophysiology of viral episodic wheeze. What are some risk factors for its development
Most wheezy preschool children have viral episodic wheeze, triggered by viral URTIs, with no interval symptoms between episodes.
Results from an abnormal immune response to viral infection causing inflammation and obstruction of the small airways
RFs: Maternal smoking during and/or after pregnancy, prematurity and being male. FHx of asthma or allergy Is NOT a RF
By what age does viral episodic wheeze generally resolve
5 years
Pathophysiology of multiple trigger wheeze
Used to describe wheezy episodes which are tiggered by many stimuli, including viral infections, cold air, dust, animal dander and exercise. A significant proportion have asthma ad most will benefit from asthma preventer therapy
Pathophysiology of atopic asthma. What conditions are associated with it
- Atopic asthma is strongly associated with eczema, rhino-conjunctivitis and food allergy
- Bronchial inflammation (oedema, excessive mucus production, cellular infiltration) leads to bronchial hyperresponsiveness, reversible airway narrowing (bronchoconstriction, airway inflammation) and symptoms
- When recurrent wheezing is associated with symptoms between viral infections (interval symptoms) and evidence of allergy to one or more inhaled allergens such as house dust mite, pollens or pets, it is called ‘atopic asthma.’
Risk factors for asthma
- Personal or FHx of atopic disease
- Male sex
- Respiratory infections in infancy and exposure to tobacco smoke or inhaled particulates
- Premature birth and associated low birth weight
- Obesity and social deprivation
When should asthma be suspected in a child
How can an asthmatic wheeze be described
Asthma should be suspected in any child with wheezing on more than one occasion, particularly if this persists between viral illnesses (interval symptoms).
Ideally, the presence of wheeze is confirmed on auscultation during an acute episode to distinguish it from transmitted upper respiratory noises, which are often loud and easy to hear in children
Asthmatic wheeze is a polyphonic (multiple pitch) noise as multiple airways of different sizes are affected
Presentation of asthma
- A chronic dry cough is common in children with asthma but is rarely the only symptom.
- Wheeze, cough, chest tightness and breathlessness worse at night and in the early morning
- May also be triggered by emotion and laughter
- Examination of the chest is usually normal between attacks
- Long-standing asthma may cause hyperinflation of the chest and generalised polyphonic expiratory wheeze with a prolonged expiratory phase
- Early onset can result in Harrison’s sulci
- Can also check for evidence of eczema and allergic rhinitis
- Growth should be monitored (can be affected in severe asthma)
- Asthma control test can help determine severity- a positive response to asthma therapy is confirmatory of asthma
What reg flag symptoms might suggest an alternative diagnosis to asthma
Failure to thrive, unexplained clinical findings (abnormal voice or cry, dysphagia, inspiratory stridor), symptoms present from birth, excessive vomiting or posseting, URTI evidence, persistent wet or productive cough, FHx of chest disease, nasal polyps
How should asthma be investigated in children < 5 years old
The diagnosis of asthma is based on history, examination and response to treatment (CXR is not necessary unless differentials need to be excluded.)
May perform a skin prick test to determine specific phenotype (eosinophilia of 4% or more and raised allergen specific IgE corroborates atopic status)
What objective asthma investigations exist (for children older than 5)
Spirometry- should be offered to all symptomatic people> 5 years. FEV1/FVC ratio is normally greater than 70%- any lower value suggests airflow limitation (a normal result when the patient is asymptomaticdoes not rule out underlying disease)
Bronchodilator reversibility testing- Should be considered in children and young people with ‘obstructive spirometry’ (FEV1/FVC < 70%)
* An improvement in FEV1 of 12% or more in response to a beta-2 agonist or corticosteroid is regarded as a positive result
PEFR- provides an estimate of the maximum rate of expiration- asthma leads to an increased variability in peak flow rate, with diurnal and day-to-day variability
* A value of more than 20% variability after monitoring at least twice daily for 2-4 weeks is regarded as a positive result
FeNO (fractional exhaled nitric oxide) testing- useful if there is diagnostic uncertainty and normal spirometry OR obstructive spirometry with negative bronchodilator reversibility test- it is a marker of airway inflammation
* A level >35ppb is considered a positive test
How can we determine the severity of an asthma attack
- Note the degree of agitation and behavioural symptoms
- Look for signs of exhaustion, cyanosis, use of accessory muscles, O2 sats
- Examine the chest, pulse rate etc
