What is the best approach to manage the flu in patients with underlying health conditions, such as asthma or chronic obstructive pulmonary disease (COPD)?

Managing Influenza in Patients with Asthma or COPD

For patients with influenza and underlying asthma or COPD, immediately initiate short-acting bronchodilators, add systemic corticosteroids (prednisone 40 mg daily for 5 days), start oseltamivir 75 mg twice daily if within 48 hours of symptom onset, and provide antibiotic coverage (co-amoxiclav first-line) if there is increased sputum purulence, volume, or dyspnea. 1

Initial Assessment and Severity Stratification

Determine severity immediately to guide disposition and treatment intensity:

• Send to emergency room immediately if respiratory rate >30/min, blood pressure <90/60 mmHg, shortness of breath at rest, confusion, hemoptysis, or bilateral chest signs suggesting pneumonia 1
• Calculate CURB-65 score for pneumonia severity: 1 point each for Confusion, Urea >7 mmol/L, Respiratory rate ≥30/min, Blood pressure (SBP <90 or DBP ≤60 mmHg), Age ≥65 years 2
• Obtain chest radiograph, electrocardiogram, and pulse oximetry in all patients with abnormal cardiorespiratory symptoms 3
• Obtain arterial blood gases if SpO2 <92% or features of severe illness 3

Bronchodilator Therapy (First-Line Treatment)

Start short-acting inhaled β2-agonists with or without short-acting anticholinergics immediately as first-line treatment 1:

• Use nebulizers if patient is too breathless to use standard inhalers effectively 1
• Alternatively, use spacer devices with metered-dose inhalers 1
• Patients scheduled to use inhaled bronchodilators at the same time as antivirals should use their bronchodilator BEFORE taking the antiviral 4
• Continue or initiate long-acting bronchodilators as soon as possible, ideally before hospital discharge 5

Systemic Corticosteroids (Essential Component)

Prednisone 40 mg orally daily for 5 days is the indicated regimen 1:

• Corticosteroids improve lung function, oxygenation, shorten recovery time, and reduce hospitalization duration in COPD exacerbations 1, 5
• This applies to both asthma and COPD exacerbations triggered by influenza 1

Antiviral Therapy

Initiate oseltamivir 75 mg orally twice daily for 5 days if the patient presents within 48 hours of symptom onset 1, 5:

• Oseltamivir reduces illness duration by approximately 24 hours and may reduce hospitalization rates 1, 2
• Reduce dose by 50% if creatinine clearance <30 mL/minute 5
• Critical caveat: Zanamivir (inhaled neuraminidase inhibitor) is NOT recommended for patients with underlying airways disease such as asthma or COPD due to risk of serious bronchospasm, including fatalities 4
• If zanamivir is considered despite this warning, it should only be used under careful monitoring with fast-acting bronchodilators immediately available 4

Antibiotic Coverage

Start antibiotics empirically based on severity and clinical features 1:

Non-severe pneumonia (CURB-65 Score 0-2):

• Co-amoxiclav is first-line because it covers common secondary bacterial pathogens including Streptococcus pneumoniae and Haemophilus influenzae 1, 5
• Doxycycline is an alternative for patients intolerant of beta-lactams 5
• Avoid macrolides as first-line due to antimicrobial resistance concerns and inferior coverage of H. influenzae 5

Severe pneumonia (CURB-65 Score 3-5):

• Initiate IV antibiotics (co-amoxiclav or second/third generation cephalosporin) 2
• Obtain blood cultures before antibiotic administration 3
• Send pneumococcal and Legionella urine antigens 3
• Obtain sputum for Gram stain and culture if patient can expectorate purulent samples and hasn't received prior antibiotics 3

Indications for antibiotics include: increased sputum purulence, increased sputum volume, or increased dyspnea 1

Oxygen Management

Maintain SpO2 ≥92% through appropriate oxygen delivery 3, 1, 2:

• High concentrations of oxygen (35% or greater) can safely be given in uncomplicated pneumonia 3
• Special consideration for COPD patients: In patients with pre-existing COPD who may have CO2 retention, start with controlled oxygen (24-28%) and titrate based on repeated arterial blood gas measurements, aiming for SpO2 >90% 3
• High concentration oxygen in COPD with ventilatory failure can reduce hypoxic drive and increase ventilation-perfusion mismatching 3
• Guide oxygen therapy by repeated arterial blood gas measurements in COPD patients complicated by ventilatory failure 3
• Non-invasive ventilation (NIV) may be helpful in COPD patients with acute hypercapnic respiratory failure 3, 1

Monitoring Strategy

Check vital signs at least twice daily, more frequently in severe illness 3, 1:

• Monitor: temperature, respiratory rate, pulse, blood pressure, mental status, oxygen saturation, and inspired oxygen concentration 3
• Use an Early Warning Score system for convenient tracking 3, 1
• In patients not progressing satisfactorily, perform full clinical reassessment and repeat chest radiograph 3

ICU/HDU Transfer Criteria

Transfer to intensive care if 2:

• Failing to maintain SpO2 >92% despite FiO2 >60% 2, 5
• Severe respiratory distress with PaCO2 >6.5 kPa 2
• Rising respiratory and pulse rates with severe distress 2
• Shock or hemodynamic instability 2
• Altered mental status/encephalopathy 2

Supportive Care

Assess for cardiac complications and volume depletion 3:

• Provide IV fluids as needed 3
• Nutritional support should be given in severe or prolonged illness 3

Discharge Criteria

Review 24 hours prior to discharge and ensure patients meet stability criteria 3, 1:

Do NOT discharge if ≥2 of the following are present 3:

• Temperature >37.8°C 3, 1
• Heart rate >100/min 3, 1
• Respiratory rate >24/min 3, 1
• Systolic blood pressure <90 mmHg 3, 1
• Oxygen saturation <90% 3, 1

Follow-Up and Prevention

Arrange follow-up for all patients who suffered significant complications or worsening of underlying disease 1:

• Follow-up clinical review should be considered for all patients with significant complications 3
• Ensure annual influenza vaccination to prevent future exacerbations 1, 5
• Consider pneumococcal vaccination as part of overall COPD/asthma management 1, 5

Critical Pitfalls to Avoid

Do not use zanamivir (inhaled antiviral) in patients with asthma or COPD due to serious bronchospasm risk 4. The FDA label explicitly states: "RELENZA is not recommended for treatment or prophylaxis of influenza in individuals with underlying airways disease (such as asthma or chronic obstructive pulmonary disease). Serious cases of bronchospasm, including fatalities, have been reported" 4.

Do not delay bronchodilators and corticosteroids while waiting for antiviral therapy—these are the foundation of treatment in patients with underlying airways disease 1.

Do not use high-flow oxygen initially in COPD patients with known CO2 retention without arterial blood gas guidance 3.

Patients who worsen or fail to improve within 48 hours of starting treatment should be reassessed for complications, alternative diagnoses, or need for hospitalization 3.