This study aims to investigate the use of cardiopulmonary coupling (CPC), as biomarker for characterizing obstructive sleep apnea (OSA) severity in children. CPC analysis is based on the time-frequency coherence (TFC) between the respiratory effort signal and heart rate variability.
We analyzed 255 children (5-10 years old) from the Childhood Adenotonsillectomy Trial 7 months after treatment for OSA, then having no, mild, moderate, and severe OSA. TFC markers are obtained during wake, rapid eye movement (REM) sleep, and non-REM (NREM) sleep.
Results showed that the TFC in the low-frequency band increased significantly with the severity of OSA in both NREM (p<0.001) and REM sleep (p<0.001). Conversely, the TFC in the high-frequency band, the usual parameter of CPC, is significantly lower when increasing OSA severity during NREM (p=0.02) and REM (p=0.03). The findings suggest that TFC could be a useful biomarker for assessing OSA severity in children, and could provide additional information about underlying pathophysiological mechanisms.