What are the diagnostic criteria and initial treatment for an asthma exacerbation?

Diagnosing and Managing Asthma Exacerbation

Diagnose an asthma exacerbation by identifying changes in symptoms (breathlessness, coughing, wheezing, chest tightness), increased rescue bronchodilator use, and decreased lung function (PEF or FEV₁) that fall outside the patient's usual day-to-day variation, then immediately classify severity and initiate treatment within 15-30 minutes. 1

Diagnostic Criteria

Clinical identification requires three key components:

• Symptom changes: Breathlessness, coughing, wheezing, and chest tightness that worsen beyond the patient's normal range 1
• Increased rescue medication use: β2-agonist use exceeding the patient's typical pattern 1
• Objective lung function decline: Measured by PEF or FEV₁ showing deterioration from baseline 1

For retrospective analysis, exacerbations are confirmed when associated with increased maintenance treatment for 3 days or more 1

Severity Classification

Classify severity immediately using objective measures—this determines treatment intensity and disposition: 1, 2

Mild Exacerbation

• Dyspnea only with activity 2
• PEF ≥70% of predicted or personal best 2
• Can speak in sentences 1

Moderate Exacerbation

• Dyspnea interfering with usual activity 2
• PEF 40-69% of predicted 1, 2
• Speaks in phrases 1
• Respiratory rate increased 1

Severe Exacerbation

• Dyspnea at rest 2
• PEF <50% of predicted 1, 2
• Cannot complete sentences in one breath 1, 2
• Respiratory rate >25 breaths/min 2
• Heart rate >110 beats/min 2
• Use of accessory muscles 1

Life-Threatening Features

• PEF <33% of predicted 1, 2
• Silent chest (absent breath sounds) 2
• Cyanosis 2
• Altered mental status, confusion, or drowsiness 2
• Feeble respiratory effort 2
• Bradycardia or hypotension 2
• PaCO₂ ≥42 mmHg (normal or elevated in breathless patient indicates impending respiratory failure) 2

Initial Treatment Protocol

Begin treatment immediately upon diagnosis—do not delay for additional testing: 2

First 15-30 Minutes

Oxygen therapy:

• Administer via nasal cannula or mask to maintain SaO₂ >90% (>95% in pregnant patients or those with heart disease) 2
• Monitor continuously 2

Bronchodilator therapy:

• Albuterol 2.5-5 mg via nebulizer OR 4-8 puffs via MDI with spacer every 20 minutes for 3 doses 2, 3
• For severe exacerbations, add ipratropium bromide 0.5 mg via nebulizer or 8 puffs via MDI every 20 minutes for 3 doses 2

Systemic corticosteroids (administer immediately, not after "trying bronchodilators first"):

• Adults: Prednisone 40-60 mg orally OR hydrocortisone 200 mg IV 2, 4
• Children: Prednisone 1-2 mg/kg/day (maximum 60 mg/day) 2
• Oral administration is as effective as IV and less invasive 2

Reassessment at 15-30 Minutes

Measure and document: 2

• PEF or FEV₁ 2
• Oxygen saturation 2
• Vital signs (respiratory rate, heart rate) 2
• Symptom response 2

Response-Based Management After Initial Treatment

Good response (PEF ≥70% predicted, minimal symptoms):

• Continue albuterol every 4-6 hours as needed 2
• Continue oral corticosteroids for 5-10 days (no taper needed for courses <10 days) 2
• Initiate or continue inhaled corticosteroids 2
• Observe 30-60 minutes after last bronchodilator dose before discharge 2

Incomplete response (PEF 40-69% predicted, persistent symptoms):

• Continue intensive treatment 2
• Consider hospital admission 2
• Continue nebulized bronchodilators more frequently 2

Poor response (PEF <40% predicted after 1-2 hours):

• Hospital admission required 2
• Consider IV magnesium sulfate 2 g over 20 minutes 2
• Consider ICU admission if life-threatening features present 2

Critical Pitfalls to Avoid

Severity is frequently underestimated by patients, families, and clinicians who fail to make objective measurements—always measure PEF or FEV₁ 2

Never administer sedatives of any kind during an acute asthma exacerbation 2, 4

Do not delay corticosteroid administration—they must be given immediately, not after attempting bronchodilators alone 2

Do not delay intubation once deemed necessary—it should be performed semi-electively before respiratory arrest occurs 2

Avoid these interventions as they lack efficacy or increase harm: 2

• Methylxanthines (theophylline)
• Chest physiotherapy
• Mucolytics
• Aggressive hydration in older children and adults
• Routine antibiotics (unless strong evidence of bacterial infection like pneumonia)

Pediatric Considerations

Young children present unique challenges: 1

• Exacerbations are frequent due to viral infections 1
• Upper airway viral symptoms may serve as early warning 1
• Severity assessment is difficult due to parental reporting dependence and inability to measure lung function reliably 1
• Many exacerbations are treated with increased inhaled corticosteroid doses rather than systemic corticosteroids—these should still be considered moderate exacerbations 1
• Nebulized medication doses should be reduced by half in very young children 4

Hospital Admission Criteria

Immediate hospital referral is required for: 2

• Any life-threatening features (PEF <33%, silent chest, altered mental status, cyanosis) 2
• Severe exacerbation features persisting after initial treatment 2
• PEF <40% predicted after 1-2 hours of intensive treatment 2

Lower threshold for admission in patients with: 2

• Presentation in afternoon/evening 2
• Recent nocturnal symptoms 2
• Previous severe attacks or ICU admissions 2
• Poor social circumstances 2

Risk Factors for Asthma-Related Death

Identify high-risk patients requiring closer monitoring: 1

• Previous severe exacerbation (intubation or ICU admission) 1
• ≥2 hospitalizations for asthma in past year 1
• ≥3 ED visits for asthma in past year 1
• Hospitalization or ED visit in past month 1
• Using >2 canisters of short-acting β-agonist per month 1
• Difficulty perceiving asthma symptoms or severity 1
• Low socioeconomic status 1
• Cardiovascular disease or other chronic lung disease 1