What is the appropriate treatment approach for a patient with elevated hematocrit and asthma?

High Hematocrit and Asthma: Clinical Significance and Management

High hematocrit in an asthmatic patient most commonly indicates chronic hypoxemia from poorly controlled asthma, and management should focus on optimizing asthma control while investigating the underlying cause of polycythemia.

Understanding the Clinical Relationship

The combination of elevated hematocrit and asthma suggests several important clinical scenarios:

• Chronic hypoxemia from poorly controlled asthma can stimulate erythropoietin production, leading to secondary polycythemia as a compensatory mechanism 1
• Dehydration during acute asthma exacerbations can cause hemoconcentration and falsely elevated hematocrit, particularly in patients receiving frequent beta-agonist therapy 2
• The finding warrants investigation to exclude other causes of polycythemia unrelated to asthma 3

Initial Assessment and Laboratory Evaluation

Obtain a complete blood count to confirm the elevated hematocrit and assess for other abnormalities 3:

• Measure arterial blood gases in patients with suspected chronic hypoxemia or severe asthma, as normal or elevated PaCO2 in a breathless asthmatic indicates life-threatening disease 1
• Check plasma electrolytes and urea concentrations, as recommended for asthmatic patients with complications 3
• Obtain chest radiography to exclude pneumothorax, consolidation, or pulmonary edema that may contribute to hypoxemia 1, 3

Asthma Management Strategy

For Stable Asthma with Elevated Hematocrit

Continue or optimize inhaled corticosteroid therapy at appropriate dosing based on asthma severity 3, 4:

• Administer inhaled beta-agonists as needed for symptom relief, with frequency determined by symptom severity 3, 4
• Monitor peak expiratory flow regularly to assess asthma control and response to treatment 3, 4
• Consider stepping up long-term controller therapy if symptoms suggest inadequate control 5

For Acute Exacerbations

Administer high-dose inhaled beta-agonists immediately: salbutamol 5 mg or terbutaline 10 mg nebulized with oxygen 1, 4:

• Give systemic corticosteroids: prednisolone 30-60 mg or intravenous hydrocortisone 200 mg immediately 1, 4
• Administer oxygen through nasal cannula or mask to maintain SaO2 >90% (>95% in pregnant women) 1
• For severe exacerbations with life-threatening features (PEF <33% predicted, silent chest, cyanosis), add ipratropium 0.5 mg nebulized to the beta-agonist 1, 4

Critical Decision Points for Hospitalization

Immediate hospital referral is required for 1, 4:

• Any life-threatening features: PEF <33% predicted, silent chest, cyanosis, weak respiratory effort, bradycardia, hypotension, exhaustion, confusion, or coma
• Severe asthma features persisting after initial treatment: respiratory rate >25 breaths/min, heart rate >110 beats/min, inability to complete sentences
• PEF 15-30 minutes after nebulization <33% of predicted or best value
• Arterial blood gas showing normal or elevated PaCO2 in a breathless patient, severe hypoxia (PaO2 <8 kPa), or low pH 1

Important Clinical Pitfalls to Avoid

Never administer sedatives to asthmatic patients, as they are contraindicated and can worsen respiratory depression 3, 4:

• Do not routinely prescribe antibiotics for elevated inflammatory markers unless bacterial infection is clearly present 3
• Avoid delaying treatment while waiting for laboratory results in acute exacerbations 1
• Do not underestimate exacerbation severity based solely on clinical appearance, as patients and physicians frequently underestimate acute asthma severity 1

Addressing the Underlying Polycythemia

Once asthma is stabilized, investigate whether the elevated hematocrit represents:

• Secondary polycythemia from chronic hypoxemia: Optimize asthma control and reassess hematocrit after achieving stable disease control 1
• Hemoconcentration from dehydration: Ensure adequate hydration, particularly during exacerbations when patients receiving beta-agonists and corticosteroids are at risk 2
• Primary polycythemia or other hematologic disorder: If hematocrit remains elevated despite optimal asthma control and adequate hydration, refer to hematology for further evaluation 3

Follow-up and Monitoring

Ensure close follow-up within one week with primary care and specialist respiratory review within one month 5:

• Monitor symptoms and peak flow readings twice daily 5
• Provide written asthma action plan to help patients recognize early signs of worsening and initiate appropriate treatment 6
• Reassess hematocrit after optimizing asthma control to determine if polycythemia resolves with improved oxygenation