Course:PostgradFamilyPractice/ExamPrep/99 Priority Topics/Asthma

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Asthma - Key Features

1. In patients of all ages with respiratory symptoms (acute, chronic, recurrent):
a) Include asthma in the differential diagnosis
b) Confirm the diagnosis of asthma by appropriate use of: history, physical examination, spirometry


Symptoms Signs Airway Obstruction
Frequent episodes breathlessness Wheezing
Chest tightness Tachypnea
Wheezing (Worse at night or early am) Decreased breath sounds
Cough (Worse at night or early am) Accessory muscle use
Triggers: URTI, aeroallergens, irritants, exercise Supraclavicular/intercostal in-drawing
Improve w/ bronchodilators, ICS Nasal flaring

DIAGNOSIS: Suspect from clinical features, objective measures of airflow obstruction for Dx:

Pulmonary Function Measurement Children (>6yrs) Adults
Spirometry (preferred)
Reduced FEV1/FVC

Increase FEV1 with Tx*

<Normal lower limits (<0.8-0.9)

≥ 12%

<Normal lower limits (<0.75-0.8)

≥ 12% (& min ≥200 mL)

Peak Expiratory Flow (alternative)
Increase w/ Tx*

Diurnal Variation

≥ 20%

Not recommended

60L/min (minimum ≥ 20%)

>8% based on BID readings
>20% based on multi day readings

Positive Challenge Test (alternative)
Methacholine challenge

Exercise challenge

PC20<4mg/mL (4-16 mg/mL = borderline, >16 mg/mL is negative)

≥10-15% decrease in FEV1 post-exercise

  • Treatment = after bronchodilators or course of controller therapy

2. In a child with acute respiratory distress, distinguish asthma or bronchiolitis from croup and foreign body aspiration by taking an appropriate history and doing a physical examination.

• FB: Hx, asymmetric, monophonic wheeze (only 1 tone), unilateral hyperinflation or FB on CXR
• Croup: swelling of vocal cords → barking cough, causes: 1)viral (75% parainfluenza) 2)bacterial (diphtheria) 3)allergies/inhaled irritants 4)GERD. URTI, + nighttime, typically 5-6d

3. In a known asthmatic, presenting with an acute exacerbation or for ongoing care, objectively determine the severity of the condition (e.g. with history, including pattern of medication use, PE, Spirometry). Don’t underestimate severity.

Asthma Severity (Method of Canadian Consensus)
Severity Mild Moderate Severe
FEV1/PEF >80% 60-80% <60%
SABA use <Q8h Q4-8h Q2-4h
Near fatal episode - - +
Hospital admission - - +
Nighttime symptoms -/+ + +++
Daily activity limitations -/+ +/++ +++

SABA=short acting β-agonist, FEV=forced exp volume, PEF=peak exp flow Symptom not reported -, reported +, reported more often ++ and +++

Asthma Control Criteria
Characteristic Frequency or Value
Daytime symptoms <4 days/week
Nighttime symptoms <1 night/week
Physical activity Normal
Exacerbations Mild, infrequent
Work/school agonist None
β-agonist <4 doses/week
FEV1 or PEF ≥90% personal best
PEF diurnal variation <10-15%

4. In a known asthmatic with an acute exacerbation:
a) Treat the acute episode (e.g. β-agonists repeatedly and early steroids, and avoid under-treatment).
b) Rule out co-morbid disease (e.g. CHF, COPD).
c) Determine the need for hospitalization or D/C (basing the decision on the risk of recurrence or complications, and on the patient’s expectations and resources).
Asthma management continuum.png

5. For the ongoing (chronic) treatment of an asthmatic propose a stepwise management plan including:
a) self-monitoring
b) self-adjustment of medication
c) when to consult back
• Create an Asthma Action Plan
Asthma Action plan.png

6. For a known asthmatic patient, who has ongoing or recurrent symptoms:
a) Assess severity & compliance with med regimens
b) Recommend lifestyle adjustments (e.g. avoiding irritants, triggers) for less recurrence & better control

Study Guide



Lougheed Canadian Thoracic Society Asthma Management Continuum-2010 Consensus Summary for children six years of age and over, and adults. Can Resp J Vol17:1;2010.
Colice G. Categorizing Asthma Severity: An Overview of National Guidelines. Clinical Med & Research. Vol 2(3): 155-63:2004

Practice SAMP

Asthma SAMP