Respiratory: Acute & Chronic Asthma in Children Flashcards
What is the most common chronic condition in children?
Asthma
What is asthma?
Asthma is a chronic inflammatory airway disease leading to variable airway obstruction. The smooth muscle in the airways is hypersensitive, and responds to stimuli by constricting and causing airflow obstruction.
Risk factors for childhood asthma?
1) FH
2) Males (however, this gender predominance tends to even out once in adulthood)
3) Poor maternal asthma control
4) Maternal smoking
5) Prematurity
6) Exposure to allergens e.g. dust mites, fungi, animal proteins
7) Respiratory infections in early life e.g. viral bronchiolitis
8) Exposure to passive smoking
A key feature of asthma is that the airflow limitation is variable and reversible.
The airflow obstruction is as a result of what three factors?
1) smooth muscle contraction
2) mucous production
3) bronchial inflammation
Typical symptoms of asthma?
1) Cough
- diurnal variability (worse at night and early morning)
- lasting >3 weeks
- can be triggered by seasons or allergens
- dry and non-productive
2) SOB
- occurs usually on exertion or on exposure to triggers (e.g. cold air, tobacco smoke, crying, exercise)
- may accompany wheeze and cough during an exacerbation
Signs seen in asthma?
1) Wheeze
- typically expiratory
- polyphonic (variable pitch)
2) Silent chest (emergency)
3) Increased work of breathing:
- tachypnoea
- use of accessory muscles of respiration
- nasal flaring
- sitting in forward posture
What are some precipitating factors for an exacerbation of asthma?
1) Cold air and exercise
2) Atmospheric pollution
3) Drugs: NSAIDs, beta blockers
4) Exposure to allergens
How can cold air & exercise precipitate an asthma attack?
Drying of the airways due to cold air and exercise leads to cell shrinkage, which triggers an inflammatory response.
What 2 drugs can precipitate an asthma exacerbation?
1) NSAIDs
2) Beta blockers
How can beta blockers precipitate an asthma attack?
Beta-blockers prevent the bronchodilatory effect of catecholamines on the airways
How can NSAIDs precipitate an asthma attack?
NSAIDs shunt the arachadonic acid pathway towards the production of leukotrienes, which are toxic to the epithelium.
What important features must be established when taking an asthma history for a child?
1) Age at onset of symptoms
2) Frequency of symptoms
3) Severity of symptoms (how many days of school missed? Can the child do PE at school? Can they play with their friends without getting symptoms? Night time symptoms?)
4) Previous treatments tried
5) Any hospital attendances (A+E or admissions – including HDU/ITU admission – ventilated?
6) Presence of food allergies
7) Triggers for symptoms: Exercise, cold air, smoke, allergens, pets, damp housing
8) Disease history: Viral infections, eczema, hay fever
9) Family history of atopy
What are some presenting features that indicate a diagnosing OTHER THAN asthma?
1) Wheeze only related to coughs and colds –> more suggestive of viral induced wheeze
2) Isolated or productive cough
3) Normal investigations
4) No response to treatment
5) Unilateral wheeze suggesting a focal lesion, inhaled foreign body or infection
What signs may indicate a severe asthma exacerbation?
1) Altered mental state (e.g. confusion, drowsiness)
2) Maximal work of breathing accessory muscle use/recession
3) Exhaustion
4) Significant tachycardia
5) Unable to talk
6) Silent chest (note: wheeze is typically a poor predictor of severity)
What investigations may be useful for the diagnosis of asthma?
N.B. In primary care, investigations are rarely performed; asthma is a clinical diagnosis and has no single diagnostic test.
1) Spirometry with reversibility testing (in children aged over 5 years)
2) Peak expiratory flow rate (PEFR) and variability (keep diary)
3) FeNO
4) Direct bronchial challenge test with histamine or methacholine
What is used for a direct bronchial challenge test in asthma?
Histamine or methacholine
When should spirometry be offered to children with asthma?
> 5 years old
What FEV1:FVC ratio indicate obstructive airway disease?
<70%
What is spirometry with bronchodilator reversibility?
To be classified as asthma, obstructive airway disease needs to show an element of reversibility, and therefore testing with bronchodilators is necessary.
For children aged 5 to 16-years-old, an improvement in FEV1 of >12% is suggestive of asthma.
For children aged 17 years-old and older, an improvement in FEV1 of >12%, plus an increase in volume of >200mL, is suggestive of asthma.
What FEV1 improvement following bronchodilator therapy indicates asthma?
improvement in FEV1 of >12%
What is the key differential for childhood asthma?
Viral induced wheeze
Management of childhood asthma?
The overarching aim of managing asthma is to achieve good symptom control.WH
What does ‘good symptom control’ mean in childhood asthma?
1) full school attendance
2) no sleep disturbance
3) <2/week daytime symptoms
4) no limitation on daily activities
5) no exacerbations
6) using salbutamol <2/week
7) maintaining normal lung function.
Stepwise management of asthma in children <5?
1) SABA (salbutamol) as required
2) + inhaled corticosteroids (8 week trial)
3) SABA + ICS + leukotriene receptor antagonist (LTRA)
4) Stop LTRA and refer the child to a specialist
What would indicate the need for the addition of an ICS in asthma in children <5?
Not controlled on previous step
OR
Newly-diagnosed asthma with symptoms >= 3 / week or night-time waking
What are the next steps following the 8 week ICS trial period for asthma in children <5?
1) if symptoms did not resolve during the trial period –> review whether an alternative diagnosis is likely
2) if symptoms resolved then reoccurred WITHIN 4 weeks of stopping ICS treatment –> restart the ICS at a paediatric low dose as first-line maintenance therapy
3) if symptoms resolved but reoccurred AFTER 4 weeks after stopping ICS treatment –> repeat the 8‑week trial of a paediatric moderate dose of ICS
Stepwise management of asthma in children aged 5-16?
1) SABA
2) SABA + low dose ICS
3) SABA + low dose ICS + LTRA
4) Stop LTRA and start LABA
5) Switch ICS/LABA for a MART regimen that includes a paediatric low-dose ICS
6) Increase ICS dose (either continuing on a MART regimen or changing to a fixed dose of an ICS and a LABA, with a SABA)
7) Seek specialist advice
What should long-acting beta-2 agonists (e.g. salmeterol) always be prescribed with?
should be prescribed in combination with a corticosteroid.
Stepwise management of asthma in adults (≥17)?
1) SABA
2) SABA + ICS
3) SABA + ICS + LTRA
4) SABA + ICS + LABA (discuss with the person whether or not to continue LTRA treatment)
5) Cahnge to ICS and LABA MART regimen with a low dose ICS
6) Consider increasing ICS to a moderate dose ((either continuing on a MART regimen or changing to a fixed dose of an ICS and a LABA, with a SABA as a reliever therapy)
7) Options:
- increase ICS to high maintenance dose (part of MART)
- a trial of an additional drug (for example, a long-acting muscarinic receptor antagonist or theophylline)
- seek specialist advice
What is aintenance and reliever therapy (MART)?
A form of combined ICS and LABA treatment in which a single inhaler, containing both ICS and a fast-acting LABA, is used for both daily maintenance therapy and the relief of symptoms as required.
A potential exam scenario is discussing inhaled steroids with a parent that is worried about potential side effects.
A common question is whether they slow growth.
What is some information about this?
There is evidence that inhaled steroids can slightly reduce growth velocity and can cause a small reduction in final adult height of up to 1cm when used long term (for more than 12 months).
This effect was dose-dependent, meaning it was less of a problem with smaller doses.
It is worth putting this in context for the parent by explaining that these are effective medications that work to prevent poorly controlled asthma and asthma attacks that could lead to higher doses of oral steroids being given.
Poorly controlled asthma can lead to a more significant impact on growth and development. The child will also have regular asthma reviews to ensure they are growing well and on the minimal dose required to effectively control symptoms.
SpO2 in mild/mod, severe & life threatening asthma attack?
Mild/mod: >92%
Severe: <92%
Life threatening: <92%
RR in mild/mod, severe & life threatening asthma attack?
Mild/mod:
- <30 (over 5’s)
- <40 (under 5’s)
Severe:
- >30 (over 5’s)
- >40 (under 5’s)
Life threatening:
- poor respiratory effort
PEFR in severe vs life threatening asthma attack?
Severe: PEFR 33-50% predicted
Life threatening: PEFR <33% predicted
Signs of a life threatening asthma attack?
1) SpO2 <92%
2) PEFR <33% predicted
3) Silent chest
4) Poor respiratory effort
5) Altered consciousness
6) Agitation/confusion
7) Exhaustion
8) Cyanosis
Ideally, what should asthma inhalers be used with to maximise their effectiveness?
A spacer device
Give a stepwise approach to technique for the typical salbutamol metered dosed inhaler (MDI)?
1) Remove the cap
2) Shake the inhaler (depending on the type)
3) Sit or stand up straight
4) Lift the chin slightly
5) Fully exhale
6) Make a tight seal around the inhaler between the lips
7) Take a steady breath in whilst pressing the canister
8) Continue breathing for 3 – 4 seconds after pressing the canister
9) Hold the breath for 10 seconds or as long as comfortably possible
10) Wait 30 seconds before giving a further dose
11) Rinse the mouth after using a steroid inhaler
If you come across a poorly controlled asthmatic who states they are taking their inhalers as prescribed, what should you ask?
Consider whether their inhaler technique is adequate, as this may be the cause of their poor asthma control.
Management of asthma attack?
1st line:
1) O2: if sats <94%
2) Nebulised SABA (salbutamol)
3) Ipatropium bromide (anti-muscuranic) added in if no or poor response to inhaled SABA
4) Corticosteroids (3 day course)
- oral prednisolone (1st line)
- IV hydrocortisone (if oral route contraindicated e.g. vomiting)
2nd line (with specialist input):
5) IV salbutamol: if there is no response to inhaled bronchodilators
6) IV magnesium sulphate
7) IV aminophylline
8) Intubation & ventilation
Safe discharge criteria following an asthma attack in a child?
1) Bronchodilators are taken as inhaler device with spacer at intervals of 4-hourly or more (e.g. 6 puffs salbutamol via spacer every 4 hours)
2) SaO2 >94% in air
3) Inhaler technique assessed/taught
4) Written asthma management plan given and explained to parents
5) GP should review the child 2 days after discharge
What is a viral induced wheeze?
An acute wheezy illness caused by a viral infection.
Pathophysiology in a viral induced wheeze?
Small children (typically under 3 years) have small airways.
When these small airways encounter a virus (commonly RSV or rhinovirus) they develop a small amount of inflammation and oedema, swelling the walls of the airways and restricting the space for air to flow.
This inflammation also triggers the smooth muscles of the airways to constrict, further narrowing the space in the airway.
Due to the small diameter of a child’s airway, the slight narrowing leads to a proportionally larger restriction in airflow.
What is Poiseuille’s law?
States that the flow rate is proportional to the radius of the tube to the power of four.
Therefore, halving the diameter of the tube decreases flow rate by 16 fold.
Wheeze is extremely common in pre-school children.
What % of children have an episode of wheeze before 18 months?
25%
Pre-school wheeze can be separated into what 2 categories?
1) Episodic viral wheeze
2) Multiple trigger wheeze
What is episodic viral wheeze?
Child only wheezes when has a viral upper respiratory tract infection (URTI) and is symptom free inbetween episodes.
What is multiple trigger wheeze?
As well as viral URTIs, other factors appear to trigger the wheeze such as exercise, allergens and cigarette smoke
Is episodic viral wheeze associated with an increased risk of asthma?
No
Is multiple trigger wheeze associated with an increased risk of asthma?
Yes
Generally, what features can differentiate between a viral induced wheeze and asthma?
Generally, typical features of viral-induced wheeze (as opposed to asthma) are:
1) Presenting before 3 years of age
2) No atopic history
3) Only occurs during viral infections
Presentation of a viral induced wheeze?
Evidence of a viral illness (fever, cough and coryzal symptoms) for 1-2 days preceding the onset of:
1) Shortness of breath
2) Signs of respiratory distress
3) Expiratory wheeze throughout the chest
Does a viral-induced wheeze cause a focal wheeze?
Neither viral-induced wheeze or asthma cause a focal wheeze. If you hear a focal wheeze be very cautious and investigate further for a focal airway obstruction such as an inhaled foreign body or tumour. These patients will require an urgent senior review.
Management of viral induced wheeze?
Treatment is symptomatic only
1st line –> short acting beta 2 agonists (e.g. salbutamol) or anticholinergic via a spacer
2nd line –> intermittent leukotriene receptor antagonist (montelukast), intermittent inhaled corticosteroids, or both
There is now thought to be little role for oral prednisolone in children who do not require hospital treatment.
What lifestyle advice should be given to parents regarding pre-school wheeze?
Parents who are smokers should be strongly encouraged to stop.
1st line management of viral induced wheeze?
SABA e.g. salbutamol or anticholinergic via a spacer
2nd line management of viral induced wheeze (after SABA)?
Intermittent leukotriene receptor antagonist (montelukast), intermittent inhaled corticosteroids, or both.
Management of multiple trigger wheeze?
Trial of either inhaled corticosteroids or a leukotriene receptor antagonist (montelukast), typically for 4-8 weeks.
