Figure 1. Each of these patients was categorized as “severe OSA” with AHI > 30 events/h.

In both clinical and research contexts, they may be considered similar. However, patient (A) had very short obstructive apneas (2-breaths duration) without significant oxygen desaturations; whereas patient (B) had very long apneas lasting over 20-breaths duration, which are associated with paradoxical breathing and very severe oxygen desaturations to a nadir SpO₂ 60%. Patient (A) showed frequent electroencephalogram disturbances and greater occurrences of heart rate variability. Patient (B) was notably having REM-related events.