Sample Entropy (Regularity Score)

Sample Entropy (SampEn) quantifies how predictable and repetitive a time series is. Applied to minute ventilation data from your PAP session, it measures how regular your breathing pattern is throughout the night.

Counterintuitively, very regular breathing on PAP therapy is often a sign of problems, not health. When the airway is persistently narrowed, each breath is forced through the same restricted opening, producing nearly identical breath patterns with low variability. Healthy breathing has natural breath-to-breath variability because the brain constantly adjusts respiratory drive based on chemical feedback.

A high Regularity Score (high Sample Entropy) indicates overly regular, monotonous breathing that may reflect sustained flow limitation. A low score reflects the healthy natural variability expected in well-controlled therapy. This is a WAT engine metric that complements FL Score and Periodicity Index for a complete assessment of ventilation patterns.