Severity of Acute Exacerbation of Bronchial Asthma
Evaluating the severity of an acute asthma exacerbation is essential for determining the appropriate management and disposition of the child. The assessment is based on clinical signs, symptoms, and objective measures like oxygen saturation and peak expiratory flow (PEF).
Severity Levels
1. Mild Exacerbation
- Symptoms:
- Breathlessness while walking, able to speak in full sentences.
- Minimal or no use of accessory muscles.
- Mild wheezing, predominantly expiratory.
- No agitation or cyanosis.
- Vital Signs:
- Respiratory rate slightly increased for age.
- Heart rate normal or slightly increased.
- Oxygen saturation ≥ 95% in room air.
- Objective Measures:
- PEF ≥ 70% of predicted or personal best.
2. Moderate Exacerbation
- Symptoms:
- Breathlessness at rest or with speaking in phrases.
- Use of accessory muscles of respiration (intercostal or suprasternal retractions).
- Louder wheezing, heard in all lung fields.
- Slight agitation, may sit in a tripod position.
- Vital Signs:
- Respiratory rate moderately increased for age.
- Heart rate moderately elevated.
- Oxygen saturation 91–94% in room air.
- Objective Measures:
- PEF 40–69% of predicted or personal best.
3. Severe Exacerbation
- Symptoms:
- Marked breathlessness; difficulty speaking more than a few words.
- Prominent use of accessory muscles with chest retractions.
- Severe wheezing, often audible without a stethoscope.
- Agitation or altered sensorium (may indicate hypoxia or hypercapnia).
- Inability to lie down or exhaustion from breathing effort.
- Vital Signs:
- Markedly increased respiratory rate or paradoxical breathing.
- Tachycardia (> 120 bpm in children > 5 years).
- Oxygen saturation ≤ 90% in room air.
- Objective Measures:
- PEF < 40% of predicted or personal best.
4. Life-Threatening Exacerbation
- Symptoms:
- Cyanosis, silent chest (minimal air entry on auscultation).
- Severe fatigue, confusion, or drowsiness.
- Unable to speak or respond appropriately.
- Poor respiratory effort or impending respiratory failure.
- Vital Signs:
- Bradycardia or cardiac arrest (late signs).
- Oxygen saturation < 90% despite oxygen therapy.
- Objective Measures:
- PEF unmeasurable or < 25% of predicted.
Additional Assessment Tools
- Pulse Oximetry:
- Provides a rapid, non-invasive measure of oxygen saturation.
- Hypoxemia: SpO₂ < 92% suggests severe exacerbation.
- Arterial Blood Gas (ABG):
- Indicated in severe or life-threatening cases.
- Findings:
- Hypoxemia (PaO₂ < 60 mmHg).
- Hypercapnia (PaCO₂ > 45 mmHg), indicating respiratory fatigue or failure.
- Respiratory acidosis (pH < 7.35).
- Chest X-Ray:
- Not routine; reserved for suspected complications (e.g., pneumothorax, pneumonia).
- Peak Expiratory Flow (PEF):
- Assess airflow obstruction if the child can cooperate.
- Compare to personal best or predicted values.
Age-Specific Considerations
- Infants and Young Children (< 5 years):
- Symptoms like feeding difficulties, lethargy, or grunting may indicate severity.
- Wheezing may be subtle; focus on accessory muscle use and respiratory rate.
- Objective measures like PEF are often impractical; rely on clinical signs and SpO₂.
- Older Children (≥ 5 years):
- Easier to assess with PEF or verbal cues about breathlessness.
- Use objective measures alongside clinical signs.
Severity-Based Management Approach
- Mild:
- Treat with short-acting beta-agonists (SABA) via metered-dose inhaler or nebulizer.
- Monitor for symptom resolution.
- Moderate:
- SABA + systemic corticosteroids (oral prednisone/prednisolone).
- Oxygen therapy if SpO₂ < 94%.
- Severe:
- High-dose SABA and ipratropium bromide.
- Systemic corticosteroids (oral or IV).
- Oxygen therapy to maintain SpO₂ ≥ 92%.
- Life-Threatening:
- Immediate resuscitation and intensive care.
- Continuous nebulization of SABA + ipratropium.
- IV corticosteroids, magnesium sulfate, and possible non-invasive ventilation or intubation.
Conclusion
The clinical evaluation of an acute asthma exacerbation in children relies on a combination of symptoms, physical findings, and objective measures. Prompt recognition of severity allows timely and appropriate management, reducing the risk of complications.
