Figure 2. Infographic describing interpretation of a posture severity plot.

(A) The circular axis, marked around the edge of the circle, corresponds to a particular torso position; 0 degrees is supine, 90 degrees is right lateral, 180 degrees is prone, and 270 degrees is left lateral. (B) At each particular angle of torso posture there extends a narrow “wedge.” The length of this wedge indicates the relative time spent at that exact angle ± 15 degrees. Therefore, taken around the entire circle, the wedge lengths represent a smoothed histogram of how much time a patient spends in a particular position. (C) The apnea-hypopnea index (AHI) associated with each individual wedge is calculated as the number of apneas and hypopneas occurring in that position, divided by the total time spent in that position. This position-specific AHI is communicated by coloring the wedge with a heat-map. This visualization therefore allows a clinician to quickly identify positional dependence of OSA in an individual with a high resolution; and therefore use this information to assist in recommending a postural therapy.