A patient using adaptive servo‑ventilation (ASV) set at 7–15 cm H₂O has an average residual hypopnea index of 6.2 events per hour and is experiencing mask leaks; what management steps should be taken?

Address Mask Leaks First, Then Reassess Residual Events

Your immediate priority is to eliminate mask leaks, as they fundamentally compromise ASV efficacy and artificially inflate residual event measurements—only after achieving leak control can you accurately determine if the residual hypopnea index of 6.2 truly represents inadequate treatment. 1

Why Mask Leaks Must Be Fixed First

Recent real-world data demonstrates that interface leaks cause PAP devices to substantially underestimate residual AHI 1. However, leaks also interfere with the ASV algorithm's ability to detect and respond to respiratory events appropriately. The relationship is bidirectional:

• Higher leaks correlate with greater discrepancy between device-reported and actual respiratory events 1
• ASV algorithms require accurate flow sensing to servo-control pressure support—leaks disrupt this feedback loop
• Your current residual hypopnea index of 6.2 may be artificially elevated due to leak-related algorithm dysfunction

Immediate Leak Management Steps

1. Mask interface assessment:

   • Evaluate current mask type, size, and fit
   • Consider switching mask styles (nasal pillows → nasal mask → full face) based on patient preference and anatomy
   • Refit or resize current interface
   • Check for facial hair, skin changes, or weight fluctuations affecting seal

2. Review leak data patterns:

   • Distinguish between intentional leak (exhalation port) and unintentional leak
   • Identify if leaks are positional (supine vs. lateral) or continuous
   • Most ASV devices flag "large leak" when unintentional leak exceeds 24-40 L/min depending on manufacturer

3. Pressure setting considerations:

   • Your current 7-15 cm H₂O range may be contributing to leaks if pressures are unnecessarily high
   • Consider whether auto-EPAP is enabled or if fixed EPAP could be optimized

After Leak Resolution: Reassess Residual Events

Once leaks are controlled (typically <24 L/min unintentional leak), repeat evaluation of residual events over 2-4 weeks before making pressure adjustments. A residual hypopnea index of 6.2 events/hour falls into a gray zone:

• Target threshold: Most guidelines consider AHI <5 events/hour optimal, though <10 is often acceptable if asymptomatic 2
• Device accuracy caveat: ASV devices may overestimate residual AHI compared to polysomnography 3, particularly for central events during wakefulness
• Clinical context matters: Assess whether patient has residual symptoms (daytime sleepiness, poor sleep quality, morning headaches)

If Residual Events Persist After Leak Control

Only proceed with these steps if leaks are resolved and residual events remain elevated:

1. Verify ASV settings are appropriate:

   • Confirm minimum pressure support is not set too low (older algorithms used fixed 3 cmH₂O minimum, newer devices allow zero pressure support during hyperventilation) 4
   • Consider whether auto-EPAP range needs adjustment vs. fixed EPAP
   • Review backup rate settings—ensure adequate for patient's respiratory pattern

2. Download and analyze detailed device data:

   • Distinguish central vs. obstructive vs. hypopnea events
   • Evaluate minute ventilation patterns (avoid hyperventilation, which can worsen central events) 5
   • Check for positional patterns or REM-related events

3. Consider confirmatory sleep study:

   • Home cardiorespiratory polygraphy or in-lab polysomnography
   • Essential if treatment adequacy is uncertain, given poor correlation between device-reported and polysomnography-measured AHI 1, 3
   • Particularly important if patient remains symptomatic despite apparently controlled device-reported AHI

Critical Safety Consideration

If your patient has heart failure with reduced ejection fraction (LVEF ≤45%) and predominant central sleep apnea, exercise heightened vigilance. While recent 2025 guidelines from both European 4 and American 2 societies have reconsidered earlier safety concerns from SERVE-HF, noting that newer evidence (ADVENT-HF) did not confirm increased mortality risk, this remains a population requiring careful monitoring and optimization of cardiac therapy alongside ASV.

Common Pitfalls to Avoid

• Don't adjust pressure settings while significant leaks persist—you'll be chasing a moving target
• Don't rely solely on device-reported AHI—it has poor agreement with polysomnography, especially with leaks present 1, 3
• Don't assume all residual events are treatment failure—ASV devices may detect central events during wakefulness that are not clinically significant 3
• Don't ignore minute ventilation data—hyperventilation can paradoxically worsen central events 5