Figure 2: Polysomnography showed a pattern of central sleep apnea syndrome. The apnea and hypopnea index (AHI) was 47.9/hour. The total duration of Cheyne-Stokes respirations was 111 minute (27.0% of the total sleep time). A representative example is noted in the panel. The Flow stopped periodically without any labored movement of the thorax or abdomen. PFlow: Pressure Flow; TFlow: Thermister Flow; THO: Thorax; ABO: Abdomen; S: Spine Position.