Figure 2.

The example of HB calculation. (A) The search window is defined as the two peaks of the averaged SpO₂ trace. (B) The nasal flow (blue) and the end points of a respiratory event (event start: yellow star; event end: purple star) are shown. (C) The SpO₂ trace of the corresponding respiratory event is shown. The desaturation area for a single event is the area above the SpO₂ trace (blue), below the desaturation baseline (magenta), and within the search window (between window start and window end). The desaturation baseline is the maximum SpO₂ value within 100s prior to the event end (yellow star). HB is calculated as the sum of desaturation events divided by the total time of sleep [14].