Asthma
Suzanne Schuh
Introduction
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True asthma and viral-induced infant wheezing (usually temporary, few progress to asthma) are difficult to distinguish; acute treatment is identical
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Occasionally, even asthmatics may develop respiratory distress due to other conditions such as allergic reaction, pneumonia, salicylate intoxication: exclude via careful history and physical exam
History
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Majority of attacks are viral-induced with history of URTI
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Current asthma medications, doses, and frequency
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Frequency of acute exacerbations in the past 6-12 months
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Hospitalizations for the past 6-12 months
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Previous ICU admission for asthma
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Atypical presentation (e.g., persistent high fever, wet cough: often signal pneumonia)
Examination
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Usual findings: tachypnea, intercostal/suprasternal retractions, expiratory ± inspiratory wheeze
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Fever (especially low-grade) and crepitations are common
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Red flags:
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Nasal flaring, grunting, poor air entry
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Pallor, duskiness
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Agitation/persistent lethargy
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Difficulty talking in sentences/feeding in infants/playing
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Investigations
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Majority require no investigations
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Pulse oximetry
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FEV1 may be indicated if uncertain diagnosis or to document response to therapy:
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FEV1 < 50% predicted: Severe asthma
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FEV1 50-70%: Moderate asthma
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FEV1 71-80%: Mild asthma
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However, some patients with significant symptoms have FEV1 > 80% predicted and others with relatively mild symptoms have FEV1 < 70%
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Chest X-ray only indicated in atypical presentation, toxic appearance, chronic symptoms, critically ill patients
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Arterial blood gas only indicated in critically ill children, abnormal level of consciousness, or increasing oxygen requirements
Emergency Management
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Supplemental oxygen if SaO2 < 90%
Salbutamol/Albuterol
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Nebulizer: 2.5-5 mg (0.5-1.0 mL) in 2-3 mL NS q 20 mins × 3 in first hour in severe disease
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Repeat if poor response
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Reevaluate hourly and prolong intervals to q 1-2 h if good response
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If no or minimal respiratory distress 1-2 hrs past last inhalation, can usually discharge
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MDI: 4-8 puffs (400-800 mcg/dose) per dose as above
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Use mask aerochamber in young patients—mouth piece (aerochamber) in children > 6 years of age
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Supplemental potassium if > 10 frequent inhalations in ED
Ipratropium
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