Visual summary of polysomnographic data

Graphical representation of an entire polysomnogram, with the beginning of data collection at left and the end of the study at right. The top line shows the variation in sleep stages through the night; directly below is a notation of body position through the night, followed by oxyhemoglobin saturation, transcutaneous carbon dioxide levels (not measured in this particular study), and maximum/minimum heart rate. At the bottom are summary signals for respiratory events, including respiratory mechanics instability (RMI; a measurement of thoracoabdominal dyssynchrony), and events that have been scored as apneas or hypopneas.