[Cardiopulmonary coupling analysis in diagnosis of sleep disorders]

Objectives: To compare diagnostic consistency for chronic insomnia (CI) and obstructive sleep apnea (OSA) between cardiopulmonary coupling (CPC) and polysomnographm (PSG). Methods: Two hundred and twenty-one patients were enrolled from the Department of Sleep Disorders, Chaohu Hospital affiliated to Anhui Medical University from July 2018 to December 2019, and monitored with overnight CPC and PSG simultaneously. According to clinical representations and PSG results, there were 88 males and 80 females with CI and OSA, including chronic insomnia (CI group, 93 cases), OSA (OSA group, 36 cases) and comorbid OSA with CI (COI group, 39 cases). The consistency of sleep and OSA parameters measured with CPC and PSG were analyzed. Results: (1)For all patients and CI group, the total sleep time (TST), sleep efficiency (SE) and rapid eye movement (REM) sleep time measured by CPC were significantly higher than those measured with PSG, and the wake time after sleep onset (WASO) was significantly lower than that measured with PSG (the specific median comparisons were as follows 420.0 min vs 395.5 min, 93.7% vs 81.8%, 90.0 min vs 37.5 min, 18.0 min vs 63.0 min in CI group, respectively; 414.0 min vs 392.5 min, 91.9% vs 81.9%, 72.0 min vs 34.8 min, 24.0 min vs 58.4 min in all patients, respectively (all P≤0.001). However, in the OSA patients, the TST, SE, WASO, REM sleep time and NREM sleep time measured using two methods were similar (all P>0.05). (2) According to OSA criteria, the consistency between CPC and PSG was fair (κ=0.255). Only CPC has a certain degree of value for OSA screening when the AHI ≥ 20/h (κ=0.580, sensitivity: 0.85, specificity: 0.82, positive predictive value: 0.59, negative predictive value: 0.95, positive likelihood ratio: 4.72). Conclusion: CPC technology may overestimate the sleep quality of CI patients, and its consistency is fair compared with that of PSG in the diagnosis of OSA.