(a) Diagnostic polysomnogram showing obstructive events (arrows). Leads from top to bottom; eye, EEG, chin, ECG, snore, nasal pressure, thermal airflow, thoracic and abdominal effort, legs movement, saturation, and heart rate. (b) Development of central events on CPAP therapy (arrows). Leads from top to bottom; EEG, eye, chin, ECG, snore, legs movement, CPAP, flow, thoracic and abdominal effort, IPAP, saturation, leak, respiratory rate, and heart rate.