Beyond Device Downloads: Residual Sleep Apnea and Hypoxemia Missed by Flow-Based CPAP Monitoring

Area of Science:

• Sleep Medicine
• Respiratory Physiology
• Telemedicine

Background:

• Positive Airway Pressure (PAP) therapy is the standard for sleep apnea treatment.
• PAP download reports assess usage, leak, and residual apnea-hypopnea index (AHI).
• Follow-up testing can provide additional insights into sleep and respiratory health during PAP therapy.

Purpose of the Study:

• To compare PAP-derived AHI (AHIFLOW) with cardiopulmonary coupling (CPC)-derived AHI3% (AHICPC).
• To evaluate residual respiratory burden in patients receiving PAP therapy.
• To identify cases where PAP therapy appears effective but residual disease may persist.

Main Methods:

• Retrospective analysis of remote physiological monitoring data from ResMed PAP devices.
• Longitudinal home sleep testing using CPC via the SleepImage system.
• Analysis of concomitant PAP and CPC data from 465 patients over 24,939 nights.

Main Results:

• Mean AHIFLOW was 2.4 events/hour, while mean AHICPC was 12.1 events/hour.
• In nights with AHIFLOW <5, 85% had AHICPC ≥5, and 47.7% had AHICPC ≥10.
• Significant residual hypoxia was observed, with 28.3% experiencing SpO2 <90% and 10.6% SpO2 <88% for ≥5 minutes.

Conclusions:

• PAP reports may underestimate residual respiratory burden and miss clinically significant residual disease.
• Device-based flow metrics alone can overlook hypoxic events, particularly during REM sleep.
• Relying solely on PAP-derived AHI risks underestimating persistent sleep apnea severity.