What is the diagnosis and appropriate treatment for a nonsmoking, nonalcoholic adult with a history of asthma, presenting with fever, chills, and wheezing?

Acute Asthma Exacerbation with Possible Respiratory Infection

This presentation of fever, chills, and wheezing in an adult with known asthma represents an acute asthma exacerbation triggered by a respiratory infection, requiring immediate bronchodilator therapy and consideration of systemic corticosteroids. 1, 2

Diagnosis

Primary Diagnosis: Acute Asthma Exacerbation

• The combination of wheezing and known asthma history makes acute asthma exacerbation the most likely diagnosis 3
• Fever and chills indicate a concurrent respiratory infection, which is the most common trigger for asthma exacerbations 4, 5
• Viral respiratory infections, particularly rhinoviruses in adults, are the predominant cause of acute asthma exacerbations 4, 5, 6

Severity Assessment Required

• Immediately measure peak expiratory flow (PEF) or FEV₁ before treatment, as this is the strongest predictor of hospitalization need 2
• Assess respiratory rate (>25/min indicates severe), heart rate (>110/min indicates severe), oxygen saturation (target >90%), and ability to speak in complete sentences 2
• Severe exacerbation features include: PEF <40% predicted, dyspnea at rest, use of accessory muscles, or inability to complete sentences 2

Differential Considerations

• Atypical bacterial infections (Mycoplasma pneumoniae, Chlamydia pneumoniae) can trigger asthma exacerbations in adults, though less commonly than viruses 4, 6
• Typical bacterial pathogens (Streptococcus pneumoniae, Haemophilus influenzae) do not typically initiate asthmatic exacerbations 4
• Consider pneumonia if fever is high-grade or chest radiograph shows infiltrates 2

Immediate Treatment

First-Line Bronchodilator Therapy

• Administer albuterol 2.5 mg by nebulization immediately 7
• Repeat albuterol every 20 minutes for the first hour (3 doses total) 2, 7
• Reassess PEF or FEV₁ 15-30 minutes after initial bronchodilator dose 2

Systemic Corticosteroids

• Initiate systemic corticosteroids early for moderate-to-severe exacerbations, as these are the cornerstone of treatment for infection-triggered exacerbations 1, 2
• Exacerbations triggered by respiratory infections respond to short courses of systemic corticosteroids even when maintenance therapies fail to prevent them 4
• Do not delay corticosteroids while awaiting response to bronchodilators in moderate-to-severe presentations 2

Oxygen Therapy

• Maintain oxygen saturation >90% (>95% if cardiac comorbidities present) 2
• Monitor continuously with pulse oximetry 2

Ongoing Management

Serial Reassessment

• Repeat PEF or FEV₁ measurements at 1 hour and beyond, as these are the strongest single predictor of hospitalization 2
• Continue monitoring vital signs, oxygen saturation, and clinical response 2
• Response to treatment after 1-2 hours is a better predictor of hospitalization than initial severity 2

Disposition Criteria

• Discharge if PEF ≥70% predicted, symptoms minimal, oxygen saturation stable on room air, and patient stable for 30-60 minutes after last bronchodilator 2
• Hospitalize if PEF <50% predicted after 1-2 hours of intensive treatment, persistent severe symptoms, or inability to maintain oxygen saturation on room air 2

Maintenance Therapy Adjustment

• Inhaled corticosteroids (ICS) remain the cornerstone of long-term asthma control 3
• For patients ≥12 years with inadequate control on low-dose ICS, consider either increasing to medium-dose ICS or adding a long-acting β-agonist (LABA) to low-dose ICS 3
• Never use LABAs as monotherapy 3

Critical Pitfalls to Avoid

• Do not rely solely on clinical assessment without objective lung function testing (PEF or FEV₁) when feasible 2
• Do not underestimate severity—absence of wheezing may indicate life-threatening "silent chest" rather than improvement 2
• Do not use antibiotics routinely unless bacterial pneumonia is confirmed, as typical bacterial pathogens do not trigger asthma exacerbations 4
• Do not continue albuterol more frequently than recommended without medical reassessment, as failure to respond indicates need for escalation 7

When to Refer or Obtain Additional Testing

• Obtain chest radiograph if pneumothorax, pneumonia, or pulmonary edema suspected 2
• Consider arterial blood gas if severe exacerbation (FEV₁ or PEF <40%) persists after initial treatment or signs of impending respiratory failure develop 2
• Normal or elevated PaCO₂ in a breathless asthmatic indicates life-threatening attack requiring immediate intensive care 2