Course:PostgradFamilyPractice/ExamPrep/99 Priority Topics/Asthma
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
CLINICAL FEATURES: Recurrent:
| 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 AND |
<Normal lower limits (<0.8-0.9) AND |
<Normal lower limits (<0.75-0.8) AND |
| Peak Expiratory Flow (alternative) | ||
| Increase w/ Tx* OR |
≥ 20% Not recommended |
60L/min (minimum ≥ 20%) OR |
| Positive Challenge Test (alternative) | ||
| Methacholine challenge OR |
PC20<4mg/mL (4-16 mg/mL = borderline, >16 mg/mL is negative) OR | |
- 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).
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
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
Resources
Lougheed et.al. 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