Does central apnea while on BiPAP (Bilevel Positive Airway Pressure) therapy increase leaks?

Central Apnea During BiPAP ST Therapy Can Increase Mask Leak

Central apneas occurring during BiPAP ST therapy can indeed increase mask leak due to patient-ventilator asynchrony and the resulting pressure differentials that occur during periods of respiratory cessation. 1

Mechanism of Increased Leak During Central Apneas

When central apneas occur during BiPAP ST therapy:

• The BiPAP device continues to deliver timed breaths at the set backup rate during periods when the patient is not initiating breaths
• This creates a mismatch between the machine's delivered breaths and the patient's respiratory effort
• The resulting pressure differentials can cause:
  • Increased unintentional leak around the mask seal
  • Mouth leak (particularly with nasal masks)
  • Potential for mask displacement during sleep

Evidence-Based Management Approach

1. Identify and Address the Leak

• Monitor leak trends during therapy - sudden increases in leak without pressure changes indicate unintentional leak 1
• Perform mask refit or readjustment whenever significant unintentional leak is observed 1
• An unacceptable leak is one significantly higher than the leak recorded from a well-fitted, secured interface at the same pressure settings 1

2. Optimize BiPAP Settings to Reduce Central Apneas

• For treatment-emergent central apneas:
  • Consider decreasing IPAP if central apneas occur 2
  • Adjust the maximum IPAP duration to prevent delayed cycling to EPAP, which can occur with excessive leak 1
  • Ensure appropriate backup rate settings in ST mode to stabilize breathing patterns

3. Address Interface Issues

• If mouth leak is present and causing symptoms:
  • Try a chin strap with nasal mask
  • Consider switching to an oronasal (full face) mask 1
• Substantial mouth leak is associated with:
  • Increased arousals
  • Decreased REM sleep
  • Oral dryness (even with humidification) 1

4. Optimize Patient-Ventilator Synchrony

• Adjust rise time (time for pressure change from EPAP to IPAP) for patient comfort 1
• Consider adjusting minimum IPAP duration to prevent premature cycling to EPAP 1
• If central apneas persist despite optimization, consider alternative modes:
  • Adaptive servo-ventilation may be more effective for treating complex sleep apnea with persistent central events 3, 4

Clinical Implications

High leak during BiPAP therapy has significant consequences:

• Reduces the ability of pressure support to augment tidal volume 1
• May lead to patient discomfort and poor adherence
• Decreases therapy effectiveness in controlling respiratory events
• Can cause sleep fragmentation and reduced REM sleep 1

Important Considerations

• BiPAP devices are leak-tolerant to a degree, but excessive leak compromises therapy effectiveness 5
• The trend in leak is often more informative than absolute leak values 1
• Intentional leak (through mask exhalation ports) increases with higher pressure settings and varies by interface type 1
• Patients with central sleep apnea may require specialized approaches beyond standard BiPAP ST therapy 6, 3

By addressing leak issues promptly and optimizing BiPAP settings to minimize central apneas, therapy effectiveness can be significantly improved, leading to better patient outcomes and treatment adherence.