The effect of continuous positive airway pressure on cardiopulmonary coupling.

PURPOSE: The aim of the study was to investigate cardiopulmonary coupling (CPC) as a tool for evaluating the efficacy of continuous positive airway pressure (CPAP) in the treatment of obstructive sleep apnea (OSA).

METHOD: The medical records of patients who had undergone either standard polysomnography (PSG-only group, n = 62) or split-night CPAP titration (CPAP titration group, n = 115) due to habitual snoring or sleep apnea were analyzed.

RESULT: The apnea-hypopnea index, CPC variables, and sleep stage (%) during the first 2 h of the sleep study did not differ between the PSG-only and CPAP titration groups. A comparison of data collected over the first 2 h and that collected over the rest of the sleep study revealed that high-frequency coupling (HFC) increased, and low-frequency coupling (LFC) and elevated LFC (e-LFC) decreased only for the CPAP titration group, while they did not change for the PSG-only group. The proportions of N1 and N3 stages and arousal index decreased while the proportion of R stage increased for both groups. The proportion of N2 stage and mean O2 saturation increased only for the CPAP titration group, while they did not change significantly for the PSG-only group. HFC increased while LFC and e-LFC decreased linearly as apnea-hypopnea index decreased for the CPAP titration group.

CONCLUSION: CPC effectively reflects the treatment effect of CPAP when compared with an electroencephalography-based sleep stage assessment.