Temporal relationship between arousals and Cheyne-Stokes respiration with central sleep apnea in heart failure...

The interplay between arousals and respiratory events during Cheyne-Stokes respiration (CSR) with central sleep apnea (CSA) in heart failure (HF) patients is still not fully understood. We investigated the temporal relationship between arousals and CSR-CSA.

Episodes of CSR-CSA during sleep stages N1-N2 were analyzed in 22 HF patients with an apnea-hypopnea index ≥15/h, dominant CSA and central apnea index ≥5/h. For each CSR-CSA cycle (apnea + hyperpnea), we determined the onset (AR_onset, relative to hyperpnea onset) and duration of detected arousals.

Arousals (N = 2348) mostly occurred within the first half of the hyperpneic phase (42.6%, AR_onset = 10.6 ± 2.1 s; duration = 10.6 ± 5.2 s) or close to hyperpnea onset (21.5%, AR_onset = -0.1 ± 0.6 s; duration = 13.9 ± 5.4 s). Within-apnea arousals were less frequent (12.4%, AR_onset = -16.0 ± 4.7 s; duration = 3.8 ± 1.4 s). The proportion of CSR-CSA cycles without any hyperpnea-related arousal was 27.5 ± 18.2%. Hyperpnea-related arousability (total number of hyperpneic arousals/total duration of hyperpneas) and apnea-related arousability were 63.4 ± 21.0/h and 23.8 ± 16.9/h, respectively (p < 0.0001).

During CSR-CSA, a significant proportion of arousals occur at hyperpnea onset, indicating a low arousal threshold. Hyperpneic arousals are not essential for CSR-CSA. Arousability markedly increases during hyperpneas, likely due to the concurrent increase in chemoreceptor stimulation.

This study extends current knowledge on the interplay between sleep instability and respiratory events during CSR-CSA.