Evaluating the clinical value of oscillatory cardiopulmonary coupling in patients with obstructive sleep apnea hypopnea syndrome by impedance cardiogram

Abstract

Objectives: For patients with obstructive sleep apnea hypopnea syndrome (OSAHS), chronic inflammation and hemodynamic oscillations caused by respiratory events contribute to cardiovascular disease (CVD). In this study, a physiological marker named oscillatory coupling factor (OCF) exacted from cardiac output (CO) was introduced. This study aimed to evaluate the clinical value of OCF and tentatively explore its predictive value of cardiovascular prognosis in OSAHS patients.

Methods: An impedance cardiogram (ICG) was used to continuously obtain the participants' CO with simultaneous polysomnography. Participants were divided into three groups: an OSAHS-CVD- group (n = 19); an OSAHS + CVD- group (n = 34); and an OSAHS + CVD + group (n = 36). The OCF was exacted from the CO by using empirical mode decompensation-based detrended fluctuation analysis (EMD-DFA).

Results: The OCF values were: OSAHS + CVD + group [1.20 (0.98-1.78)] > OSAHS + CVD- group [1.14 (1.02-1.94)] > OSAHS-CVD- group [0.95 (0.56-1.16)], (p = 0.001). A Spearman test showed that OCF was positively correlated with age, apnea/hypopnea index (AHI), microarousal index (MAI), oxygen desaturation index (ODI), and negatively correlated with the lowest SpO2. Ten participants were treated by one-night continuous positive airway pressure (CPAP): their AHI decreased from 44.9 (18.0-72.9)/hour to 1.25 (0.0-7.5)/hour, and their OCF fell from 1.17 (1.10-1.69) to 1.08 (0.96-1.23) (p = 0.038). Seventy-seven participants were effectively followed up. Seven participants developed CVD events or newly diagnosed CVD; their OCFs were distributed on a relatively high level [1.18 (1.01-1.56)].

Conclusion: The OSAHS participants had higher OCFs than those without OSAHS, while CVD made the OCFs even higher; CPAP could rectify this change. Oscillatory coupling factor may be a physiological marker of cardiopulmonary coupling and have potential cardiovascular prognostic value for people with OSAHS.

Keywords: Detrended fluctuation decomposition; Empirical mode decomposition; Impedance cardiogram; Obstructive sleep apnea hypopnea syndrome; Oscillatory cardiopulmonary coupling.