When should patients with severe asthma exacerbations or pneumonia, especially the elderly or immunocompromised individuals, be referred to a higher level of care or a specialist?

When to Refer Patients with Severe Asthma Exacerbations or Pneumonia

Patients with severe asthma exacerbations demonstrating life-threatening features—including peak expiratory flow <33% predicted, silent chest, cyanosis, inability to complete sentences, respiratory rate >25/min, heart rate >110/min, or altered mental status—require immediate transfer to higher-level care capable of providing ventilatory support. 1, 2

Immediate Emergency Referral Criteria (Life-Threatening Features)

Objective measurements trump clinical impression—never rely on patient or family perception of severity alone. 2

Critical Vital Signs and Physical Findings

• Peak expiratory flow <33% of predicted or personal best 1, 2
• Silent chest, cyanosis, or feeble respiratory effort 1, 2
• Bradycardia or hypotension 1
• Exhaustion, confusion, drowsiness, or coma—drowsiness is particularly predictive of impending respiratory failure 1
• Severe hypoxemia (PaO₂ <55 mmHg or <7.3 kPa) or hypercapnia on room air 2
• Normal or elevated PaCO₂ (5-6 kPa) in a breathless asthmatic patient—this indicates severe respiratory muscle fatigue 1

Severe Exacerbation Features Requiring Immediate Higher-Level Care

• Respiratory rate >25 breaths/min 1, 2
• Heart rate >110 beats/min 1
• Too breathless to complete sentences in one breath 1
• Peak flow <50% predicted with severe breathlessness 1, 2
• FEV₁ or PEF <40% predicted after initial treatment in the emergency setting 1
• Patients who fail to improve after 1-2 hours of aggressive initial treatment have >84% chance of requiring hospitalization 1

Specialist Referral for Chronic Severe Asthma Management

Refer to a respiratory physician when patients demonstrate continuing symptoms despite high-dose inhaled corticosteroids or require Step 4+ therapy (medium-to-high dose ICS + LABA). 1, 2, 3

Diagnostic Uncertainty Requiring Specialist Input

• Elderly patients and smokers with wheeze where COPD, heart failure, or other conditions may coexist 1, 2
• Unexplained systemic symptoms (fever, rash, weight loss, proteinuria) suggesting eosinophilia or vasculitis 1, 2
• Possible occupational asthma 1, 2
• Symptoms disproportionate to measured lung function 2
• Onset of breathlessness in patients <40 years old to identify α₁-antitrypsin deficiency 2

Treatment-Refractory Disease

• Catastrophic, sudden severe (brittle) asthma 1, 2
• Continuing symptoms despite high-dose inhaled steroids 1, 2
• ≥2 exacerbations requiring oral corticosteroids in past year 2, 3
• Any hospitalization for asthma 2, 3
• Step 4 or higher treatment required 2, 3
• Difficulty achieving or maintaining control despite appropriate therapy 2, 3
• Consideration for long-term nebulized bronchodilators 1
• Asthma interfering with lifestyle despite treatment changes 1, 2

Special Populations Requiring Specialist Care

• Pregnant women with worsening asthma 1, 2
• Patients recently discharged from hospital 1
• Immunocompromised individuals with severe exacerbations—these patients are at higher risk for rapid decompensation and should have a lower threshold for referral 2

Pneumonia-Specific Referral Considerations

For elderly or immunocompromised patients with pneumonia, refer when there is compromised respiratory function (FVC <80%) with acute deterioration, as they are at high risk of rapid decompensation. 2

High-Risk Features in Pneumonia Patients

• Onset of cor pulmonale (right heart failure) requiring confirmation and treatment optimization 2
• Suspected aspiration or bulbar dysfunction with recurrent chest infections 2
• Severe hypoxemia or hypercapnia on room air 2
• If not fully improved in 2 weeks after treatment initiation, obtain chest radiography and consider specialist referral 2

Post-Discharge Follow-Up Requirements

Schedule follow-up with primary care provider and/or asthma specialist within 1-4 weeks of emergency department discharge or hospitalization. 1, 3

• Encourage telephone contact with asthma care provider during first 3-5 days after discharge 1
• Follow-up visit is essential to review written asthma action plan, adherence, environmental control, and consider step-up in therapy 1
• Consider referral to asthma self-management education program 1

Common Pitfalls to Avoid

Do not underestimate severity based on patient or family perception alone—objective measurements (peak flow, spirometry, oxygen saturation) are essential, as attacks are often underestimated and can be fatal if not recognized. 1, 2

Do not delay referral in patients with neuromuscular disease—they may not display typical labored breathing or accessory muscle use despite severe respiratory compromise. 2

Verify medication adherence, correct inhaler technique, environmental trigger control, and treatment of comorbidities (rhinitis, sinusitis, GERD, OSA, obesity) before attributing poor control to disease severity alone. 3

Repeat assessments after initial treatment, not single assessments on admission, are most useful for predicting need for hospitalization—pulse oximetry and lung function at 1 hour are strongest predictors. 1