asthma in children

Question 1

what is the pathogenisis of asthma?

Answer 1

chronic airway inflammation and bronchospasm driven by atopy and exposure to allergens

acutely allergens bind to IGE which leads to mast cell degranulation

allergens also cause expression of TH2 cells in genetically susceptible individuals which release inflammatory mediators- il5 activates eosinophils which causes the late phase reaction in asthma

Question 2

which virus is thought to be associated with asthma

Answer 2

• respiratory syncytial virus (rsv)- in either the antenatal period or childhood infection

Question 3

what are some triggers of asthma?

Answer 3

tobacco smoke, dust mites, pets, cold weather and exercise.

Question 4

what are risk factors for asthma?

Answer 4

Personal or family history of atopy: e.g. eczema and allergic rhinitis
Passive smoking
Antenatal factors: maternal smoking, RSV infection during pregnancy
Low birthweight
Maternal smoking around the child
Bottle-fed (rather than breastfed)
Significant allergen exposure: e.g. dust mites
Air pollution

Question 5

what are symptoms of asthma?

Answer 5

sob
dry cough
wheeze and chest tightness
atopic features such as eczema

Question 6

what are signs of asthma?

Answer 6

diurnal peak expiratory flow variation
dyspnoea
wheeze

Question 7

what investigations are done for children <5 you suspect have asthma?

Answer 7

• diagnose and treat based on clinical findings- you can do investigations after the age of 5

Question 8

what are the 4 different types of investigations you can do for asthma between the ages of 5-16?

Answer 8

1. Spirometry: first-line investigation; FEV1/FVC <70% is a positive result (obstructive)
2. Bronchodilator reversibility (BDR): consider if obstructive spirometry is present; an improvement of FEV1 by ≥12% is a positive result
3. Fractional exhaled nitric oxide (FeNO): performed if there is normal spirometry or obstructive spirometry with a negative BDR test; >35 ppb is positive in children

nitric oxide levels give an indication of the level of inflammation in the lungs

4. PEFR: measured multiple times a day over
   2-4 weeks and performed if spirometry, BDR and FeNO are inconclusive. Variability of >20% throughout the day is a positive result

Question 9

what are the paediatric low, moderate and high doses for ICS?

Answer 9

Paediatric low dose: ≤ 200 micrograms budesonide (or equivalent)

Paediatric moderate dose: 200-400 micrograms budesonide (or equivalent)

Paediatric high dose: > 400 micrograms budesonide (or equivalent)

Question 10

what does a MART inhaler consist of?

Answer 10

MART (maintenance and reliever therapy); this is combined fast-acting LABA and ICS for symptomatic relief and maintenance in a single inhaler. The LABA component of a MART can only contain a fast-acting LABA (e.g. formoterol)

Question 11

what are the 4 steps for managing asthma in <5s?

Answer 11

step 1: SABA

step2: SABA + trial paediatric moderate dose ICS for 8 weeks

After 8 weeks, cease the ICS and monitor symptoms:
a) If symptoms did not improve during trial: consider if an alternative diagnosis is possible

b) If symptoms resolved but recur within 4 weeks of stopping the trial: restart paediatric low-dose ICS
c) If symptoms resolved but recur beyond 4 weeks stopping the trial: repeat 8‑week trial of paediatric moderate dose ICS

step 3: SABA + paediatric low dose ICS + LTRA

step 4: Stop LTRA + seek expert opinion

Question 12

what are the 7 steps of managing asthma in 5-16s?

Answer 12

1. treat newly diagnosed children with SABA
2. if SABA doesn’t work, or newly diagnosed with sx >3 weeks/ night time waking -> SABA + paediatric low-dose ICS
3. SABA + paediatric low-dose ICS + LTRA
4. SABA + paediatric low-dose ICS + LABA + consider stopping LTRA
5. SABA + switch ICS/LABA to MART
6. increase ics to moderate dose within MART
   OR
   remove MART and give SABA+moderate ics + LABA
7. SABA + one of the following:
   a) Increase ICS to paediatric high-dose (fixed-dose or MART)
   b) Trial an additional agent: e.g. theophylline
   c) Seek an expert opinion

Question 13

what are some complications of paediatric asthma?

Answer 13

1. Asthma exacerbation: typically triggered by a viral upper respiratory tract infection in children
2. Steroid use: high dose inhaled steroids can impact growth in children
3. Pneumothorax: when bronchospasm and hyperinflation increase the pleural pressure, pleural bleb rupture may occur in susceptible individuals, resulting in a pneumothorax

Question 14

what is an example of a leukotriene receptor antagonist?

Answer 14

montelukast

Question 15

what is an example of a SABA?

Answer 15

salbutamol

Question 16

what is the mechanism of action of salbutamol?

Answer 16

Activation of β2 adrenergic receptors causes smooth muscle relaxation in the lungs, resulting in dilation and opening of the airways (bronchodilation)

Question 17

what are side effects of salbutamol?

Answer 17

tachycardia, palpitations, fine tremor, headaches

Question 18

what are side effects of ICS?

Answer 18

sore throat, cough, oral candidiasis (thrush), stunted grown in children

Question 19

what are examples of LABA?

Answer 19

Salmeterol

Formoterol: has a fast-acting component and is used in a MART

Question 20

When is LABA used?

Answer 20

when a SABA + ICS + LTRA are not effective

Question 21

what is the mechanism of action of LTRA?

Answer 21

Leukotrienes are mainly produced by mast cells and eosinophils, thus promoting bronchoconstriction, inflammation, increased permeability, and mucus secretion. LTRAs target this pathway

Question 22

what are side-effects of LTRA?

Answer 22

irritability, akathisia (feeling restless) and insomnia (uncommon)