Periodic breathing and state instability during supine laboratory recordings in chronic heart failure patients.

This study was conceived to analyze EEG state transitions and their relationship with ventilatory oscillations during daytime supine periodic breathing (PB) in heart failure patients. To this purpose, a semi-automated, frequency-based methodology was developed, and testing was carried out in 5 patients with PB. We found that apneas and hypopneas very often (86% on average) begin in synchrony with transitions from wakefulness to theta activity, and end in synchrony with the opposite transition. These results suggest that in these patients chemical instability secondary to the impaired hemodynamics coexists and interacts with state instability.