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