Is permissive hypercapnea (elevated carbon dioxide levels) an acceptable approach for patients with heart failure experiencing Cheyne-Stokes breathing?

Permissive Hypercapnia in Heart Failure Patients with Cheyne-Stokes Breathing

Permissive hypercapnia should be considered an acceptable approach for heart failure patients with Cheyne-Stokes breathing as it may represent a compensatory mechanism that should not be suppressed. 1

Understanding Cheyne-Stokes Breathing in Heart Failure

Cheyne-Stokes respiration (CSR) or Cheyne-Stokes breathing is characterized by:

• An oscillatory pattern of respiration with crescendo-decrescendo changes in tidal volume alternating with periods of apnea or hypopnea 1
• Occurs primarily during light sleep (stages N1 and N2) when ventilation is under chemical control 1
• Associated with advanced heart failure and parallels the severity of heart failure 1
• Characterized by respiratory alkalosis (low PaCO2 and high pH) 1

Physiological Basis for Permissive Hypercapnia

Several physiological mechanisms support permissive hypercapnia as an acceptable approach:

• CSR-CSB appears to be a compensatory mechanism that offsets adverse effects of heart failure 1
• The periodic rest (apnea) interspersed with hyperventilation improves breathing efficiency and reduces respiratory muscle fatigue 1
• The respiratory alkalosis (elevated pH) provides a protective buffer for the failing heart against potential acidosis 1
• The hyperventilation phase increases end-expiratory lung volume by approximately 1L, which:
  • Increases oxygen stores
  • Helps overcome restrictive ventilatory defects
  • Is particularly beneficial when patients are in supine position 1

Evidence Against Suppressing Cheyne-Stokes Breathing

Attempts to suppress CSR through various interventions have shown concerning results:

• Medications that stimulate ventilation (acetazolamide, theophylline) reduce periods of central apneic rest but increase unrelenting hyperventilation, which may be detrimental 1
• These drugs can cause electrolyte disturbances, laryngeal spasm during sleep, and cardiac arrhythmias 1
• Methods that increase ventilation (CO2 inhalation or increased dead space) worsen sleep quality without improving cardiac function 1
• Adaptive servo-ventilation (ASV), designed to suppress CSR, has been associated with increased mortality in heart failure patients with reduced ejection fraction 1

Clinical Approach to Heart Failure Patients with CSR

The recommended approach includes:

• Focus on optimizing guideline-based heart failure therapy as the primary intervention 1
• Recognize that CSR may be a marker of heart failure severity rather than a primary therapeutic target 1
• Understand that CSR often improves with effective treatment of the underlying heart failure 1
• Avoid interventions specifically aimed at suppressing the breathing pattern if heart failure therapy has been optimized 1

Important Caveats and Considerations

• CSR should be viewed as a sign of significant heart failure, similar to how elevated body temperature reflects infection 1
• The presence of CSR should prompt thorough evaluation and optimization of heart failure management 1
• Permissive hypercapnia should be considered after optimal medical therapy for heart failure has been implemented 1
• Benzodiazepines may be used for acute insomnia management while heart failure is being treated but should not be prescribed long-term specifically to treat CSR 1

While some studies suggest CSR is associated with increased mortality 2, this may simply reflect the severity of underlying heart failure rather than a direct harmful effect of the breathing pattern itself 1.