Fig. 3.

Time course of PSG signals and WP respiratory movement and systolic upstroke index signals. Time-course of respiratory signals during central apnea events in a patient. Signals, from top to bottom, are respiratory chest movement, upstroke index, nasal air flow, and abdominal belt (ABD). Red boxes indicate normal breathing while the blue boxes indicate the reduced respiratory chest wall movement and upstroke index during a central apnea