Asthma, Chronic

Chronic inflammation of the airways resulting hyper-responsiveness and chronic obstruction of airways.

Asthma prevalence is associated with ‘atopy’ & mortality have been increased in the last few decades apart from hospitalisations, missed school days etc

Immune response is

Immediate (from bradykinin, cytokines, histamine) with bronchospasm and mucus secretion.

Responds to beta-2 agonists & prevented by Mast-cell stabilisers

or

Delayed (from cellular infiltrates, leukotrines, prostaglandins) with ongoing bronchospasm & oedema

Responds to systemic steroids & prevented by inhaled corticosteroids

Common triggers for exacerbation:

– Infections (Viral URTI, sinusitis, LRTI etc)

– Allergens (pollens, dust mites, animal dander, mold)

– Other irritants: Cigarette smoke (active or passive), air pollution, perfumes etc

– Exercise: especially in cold air

– Medications: Aspirin, NSAIDs, beta-blockers

– Other: food allergies, stress, etc

Risk Factors for Persistent Asthma in childhood

– Atopic conditions- eczema, allergic rhinitis, Food allergies, etc

– Severe bronchiolitis in infancy

– F/H/O asthma or atopic conditions

– Recurrent wheeze in early childhood

– Exposure to cigarette smoke

– Gastro-oesophageal reflux disease

– Other: Male, IUGR, Obesity etc

History

– Onset, duration & progress of breathlessness

– Preceding cough-cold or ENT infections or Fever

– Triggers for exacerbation (infection, pollen, animals, smoke etc)

– If known asthma/ recurrent wheeze, enquire about:

   Background symptoms & frequency of wheeze

   Night cough or exercise induced symptoms

   Atopic predisposition (Eczema, Hayfever, Allergies) & F/H/O atopy or Asthma

   Background treatment- reliever or preventor inhalers?

   Reversibility of wheeze with beta2 agonists

   Compliance and Technique, Using Spacer? Keeping PEFR diary?

   Seasonal variation in symptoms

– Previous frequency of wheezy episodes/ exacerbations

– Previous admission to hospital/ needing IV Salbutamol/ PICU?

– Any symptoms of alternative respiratory diagnosis- stridor, weight loss, etc?

Examination

– Temperature, RR, HR, SaO2

– ENT, lymphadenopathy, hydration

– Any upper airway noises?

– Increased work of breathing- recessions, nasal flare, tracheal tug

– Chest- Equal air entry / any quiet areas?

– Prolonged expiration, wheeze, any crepts?

– Harrison’s sulcus in chronic asthma

  (normal chest examination does not exclude asthma)

– Exclude cardiac failure (murmur, gallop, large liver)

Investigations

– Spirometryshows obstructive pattern

   Reduced FVC & Reduced FEV1/FVC ratio < 0.8

   Bronchodilator response (inhaled β2-agonist) increases FEV1 ≥12%

   Exercise challenge reduces FEV1 ≥15%

– PEFR diary, often shows morning-to-afternoon variation ≥20%

   During exacerbation, PEFR is reduced compared to patient’s best PEFR

– FeNO(Fractional excretion of exhaled Nitric Oxide)

   Relatively new test, not widely available; Adds information to assist diagnosis or check poor compliance with treatment

– Bloods– Raised Eosinophils, Total IgE & specific RAST

Cap Gas / ABG- in severe episode, may show respiratory failure in acute severe asthma with low pH and high pCO2 (respiratory acidosis)

– Allergy skin testing

– Chest Xray: Not routinely required as often normal;

   may show hyperinflation, atelectasis, peribronchial thickening;

   sometimes done to exclude pneumothorax or consolidation

UK practice:

Step 1: mild intermittent asthma – inhaled Salbutamol as needed.
Step 2: regular preventer therapy – add inhaled Beclomethasone 200-400 micrograms/day

Step 3: add-on therapies – add in Salmeterol OR increase the dose of inhaled Beclomethasone to 400 micrograms/day; then add either Montelukast or slow-release theophylline.
Step 4: persistent poor control – increase inhaled Beclomethasone to 800 micrograms/day
Step 5: continuous or frequent use of oral steroids – use in the lowest dose to provide control whilst maintaining high-dose inhaled steroids and refer to respiratory paediatricians.

Long-term asthma management aims to

– Achieve good control of symptoms, including during night or exercise

– Reduce exacerbations and use of Salbutamol

– Improve lung function (PEFR)

– Minimise side effects from medications with step-wise approach

– Empower patients to recognize symptoms, triggers, avoid allergens, exacerbations and follow asthma-plan