Residual AHI vs Objective Testing: Which is Accurate?

About this episode

In this episode of Talking Sleep, host Dr. Seema Khosla welcomes Dr. Sahil Chopra to discuss research challenging a fundamental assumption: that residual AHI measurements from PAP device downloads accurately reflect whether patients' sleep apnea is adequately treated. Sleep medicine clinicians routinely rely on residual AHI from PAP downloads to determine treatment success, typically targeting an AHI under 5. But what if this metric significantly underestimates untreated sleep apnea? Dr. Chopra's study comparing PAP-determined residual AHIs to cardiopulmonary coupling (CPC)-derived AHIs reveals striking discrepancies: mean residual AHI was 2.4 via PAP download versus 12.1 via objective testing. Even more concerning, 85% of nights showing residual AHI under 5 on PAP downloads had elevated AHI based on objective CPC measurement. Dr. Chopra explains why he chose cardiopulmonary coupling as the comparator metric, using a PPG-based wearable ring worn for 7-10 nights. He clarifies why PAP devices may systematically underestimate residual disease through mask leak, unstable breathing, and periodic breathing patterns. A particularly concerning finding involves residual hypoxia. Dr. C