Asthma

Diagnosis

• History of variable respiratory symptoms (wheeze, shortness of breath, chest tightness, cough)

  • Symptoms vary over time and in intensity

  • Worse at night or early morning (on waking)

  • Triggered by endogenous/exogenous stimuli (exercise, laughter, allergens, changes in weather, irritants - eg. car fumes, viral infections)

  • Generally more than one respiratory symptom (wheeze, dyspnea, cough, chest tightness) 

    • Isolated cough in adults is seldom due to asthma

  • Worsen after stopping exercise (specific for asthma)

• Less likely asthma if:

  • Chronic sputum production

  • Shortness of breath associated with dizziness, light-headedness or paresthesia

  • Chest pain

  • Exercise-induced dyspnea with noisy inspiration

  • Localized wheeze

• Variable expiratory airflow limitation:

  • Post-bronchodilator reversibility increase in FEV1 >12% (minimum of 200mL in adults) 

  • Excessive variability in twice-daily (diurnal) PEF over 2 weeks (adults >10%, children >13% daily diurnal variability)

  • Significant increase in lung function after 4 weeks of anti-inflammatory treatment (adults FEV1 >12% and >200mL increase from baseline)

  • Positive exercise challenge test  (adults decrease FEV1 >10% and >200mL or in children decrease FEV1>12% predicted or PEF >15%)

  • Positive bronchial challenge test/methacholine (Fall FEV1≥20% or ≥15% with standard hyperventilation, hypertonic saline or mannitol challenge)

  • Excessive variation in lung function between visits *less reliable (FEV1>12% and 200mL in adults)

• Note: Previously, asthma required documented airflow limitation: Reduced FEV1/FVC (<0.75-0.8 in adults and <0.9 for children) 

Diagnosis in Preschoolers (one to five years of age)

1. Recurrent acute wheezing episodes or at least 1 acute wheezing episode with asthma-like symptoms (eg. dry cough or wheeze after running/laughing/crying or during sleep) between episodes

2. Response to SABA within minutes, or reduced frequency or severity of asthma-like symptoms during 2-3 months trial of daily ICS

3. No clinical evidence of an alternative diagnosis

Wheezing in Infants/Children DDx

• Asthma

• GERD

• Infectious

  • Bronchiolitis (<2yo, wheezing/crackles, increased respiratory effort)

  • Croup

  • Pneumonia

  • Viral-induced wheezer (<5yo, recurrent viral-triggered wheezing without symptoms between episodes)

• Foreign body aspiration

• Cystic fibrosis

• Tracheobronchial anomalies (vascular rings)

• Mediastinal mass

• Congenital heart disease / Heart failure (hepatomegaly, poor weight gain)

Pharmacological therapy

1. ICS + LABA PRN (reliever) in 6+ years old

   • Symbicort Turbuhaler (budesonide/formoterol) 200/6 mcg 1 inh PRN, seek medical care if >12inh in any day (or >8inh in any day if aged 6-11yo)

2.  Optional : ICS maintenance + SABA PRN (reliever)

   • Flovent HFA (fluticasone) 50, 125, 250mcg 1 inh BID

   • Pulmicort Turbuhaler (budesonide) 100, 200, 400mcg 1 inh BID

   • Ciclesonide (Alvesco) 400 mcg once daily

   • Starting doses: Flovent 100-250mcg, Pulmicort 200-400mcg

3. ICS + LABA maintenance and PRN in 6+ years old

   • Symbicort Turbuhaler (budesonide/formoterol)100/6, 200/6 mcg 1-2 inh BID (max total including maintenance and reliever 72 mcg formoterol/24h)

     • Reliever 200/6 mcg 1 inh PRN (max 6 inh/time)

   • Advair Diskus (fluticasone/salmeterol) 100/50, 250/50, 500/50mcg 1inh BID 

4. Refer for add-on treatment (LAMA Tiotropium, anti-IgE, anti-IL5, oral steroids, Bronchial thermoplasty, SC/SLIT)

• LTRA are less effective than ICS

  • Consider if unable/unwilling to use ICS or in concomitant allergic rhinitis

  • Singulair (Montelukast) 5, 10mg 1 tab PO PRN

• In <5yo, use MDI with spacer and face mask or nebulizer, and dose-adjust

Recommendations for initial controller therapy

• If symptoms <2/month and no risk factors

  • Consider no controller

• If symptoms >2/month or risk factors

  • Consider Low-dose ICS

• If symptoms >2/week

  • Low-dose ICS 

• Asthma most days or waking due to asthma ≥1/week

  • Medium/high-dose ICS or Low dose ICS/LABA

• Severely uncontrolled asthma or acute exacerbation

  • Short course oral corticosteroids AND High-dose ICS or Moderate-dose ICS/LABA

Exacerbation

Self-Management (Action Plan)

Early intervention in worsening asthma is key

• Increase reliever frequency

• Increase usual controller

  • Quadruple ICS or Quadruple maintenance ICS/formoterol (max formoterol 72mcg/day)

• Severe exacerbation (PEF <60%) or not improving after 48h

  • Oral corticosteroids and contact doctor

    • Prednisolone 1mg/kg/day (40-50mg)

Hospital Management

• Initial assessment

  • ABC

  • Life-threatening signs: Drowsiness, Confusion, Silent chest

    • Consult ICU, SABA, O2, prepare for intubation

• Assess severity based on dyspnea, RR, HR, O2 sat, Lung function (or PRAM score)

  • Mild-moderate

    • Talks in phrases, not agitated, Pulse 100-120, O2>90%

  • Severe

    • Talks in words, agitated, RR>30/min, Accessory muscle use, Pulse >120bpm, O2 <90%

• Oxygen (Target 93-95%)

• Consider epinephrine IM for anaphylaxis

• SABA MDI with spacer 4-8 puffs or 5mg nebulizer q20 mins x 3 (for one hour) 

  • Then depending on severity, SABA 4-8 puffs q1-4 hours

    • No additional SABA if PEF >60-80% of predicted or personal best x4 hours

    • New spacer should be washed or primed with 20 puffs of salbutamol (because of static charge)

• Early oral corticosteroids

  • Methylprednisolone 40mg IV q12h (1-2mg/kg/day divided BID) until improved 

  • Prednisone 40-60mg daily (1-2mg/kg/day divided BID) x 3-5d for children, 5-7d for adults

  • Dexamethasone 12-16mg daily (0.6mg/kg/day) for 1-2 doses

    • Consider longer 5-10 days depending on severity, taper glucocorticoids if >10d course

• If severe

  • Ipratropium bromide (Atrovent) MDI/spacer 4-8 inh or 0.5mg neb q20 mins then PRN q1-4h

  • Consider MgSO4 2g (25-75mg/kg/dose) IV over 20 minutes

  • Transfer to acute care facility

• Measure lung function after one hour of treatment

  • PEF<60% of predicted or best, or clinically not improved -> SEVERE

    • Continue treatment and reassess

  • PEF 60-80% of predicted or best -> MODERATE

    • Consider Discharge

• Discharge if no SABA x4h, PEF >60-80% of best or predicted, O2 >94% on RA

  • Reduce reliever to as needed

  • Start controller or step-up controller for 2-4 weeks

  • Continue steroids if started, eg. Prednisone 30-50mg (or 1-2mg/kg/day) PO x 5 days

  • Review action plan (and modify if needed)

  • Early follow-up within 1 week