Adherence to CPAP in summer to autumn predicts self-reported common cold symptoms in patients with obstructive sleep apnea in winter: A prospective observational study.

OBJECTIVE: We conducted a prospective observational study to determine the relationship between adherence to continuous positive airway pressure (CPAP) and susceptibility to the common cold in moderate-to-severe obstructive sleep apnea (OSA) patients. METHODS: We prospectively investigated the number of days with common cold symptoms from November 2019 to February 2020. The rate of CPAP use for 4 h/night in the preceding four months (July to October 2019) was used as a measure of CPAP adherence. Multiple generalized linear models were used to evaluate the association to days of common cold symptoms after controlling for demographic variables, habitual short sleep duration, and insomnia severity. RESULTS: We included 123 outpatients (median age 63 years) with moderate-to-severe OSA treated with CPAP. In the multivariate generalized linear model, better CPAP adherence was independently significantly associated with days with fewer common cold symptoms (ß = -0.248, P = 0.031); meanwhile, the severity of insomnia and habitual short sleep duration was not significantly associated with it. Subgroup analyses revealed that the association between CPAP adherence and days with common cold symptoms was also significant in young to middle-aged (<65 years) participants (ß = -0.407, P = 0.005). In contrast, the association was negligible in older (≥65 years) participants. CONCLUSIONS: CPAP adherence may be protective against viral infections in patients with moderate-to-severe OSA. This effect appears to be more pronounced in young to middle-aged patients with OSA.

Gender-specific impacts of apnea, age, and BMI on parasympathetic nerve dysfunction during sleep in patients with obstructive sleep apnea.

BACKGROUND: The gender-specific influences of various confounding factors, including apnea, age, BMI, and cigarette consumption, on the function of the parasympathetic nerve system (PNS) during sleep in OSA patients has never been investigated. METHODS: One hundred ninety-seven males and 63 females with OSA were subjected to full PSG examinations including assessment of R-R intervals (RRIs) during an overnight ECG. The PNS-derived modulatory effect on the RRIs and the variability of this effect were quantified during REM and NREM using instantaneous time-frequency analysis with complex demodulation. The spectral domain with the maximum instantaneous amplitude in the high-frequency band between 0.15 and 0.4 Hz was defined as the main HF peak and used as a surrogate marker of PNS discharge. Based on density-spectrum-array maps of the main HF peaks (HF-DSA map), shifts in the central frequency of the main HF peak over time were continuously observed. When the main HF peaks on the HF-DSA maps maintained the same central frequency for more than 20 sec or 5 min, the PNS functions were considered to be "stable" or "very stable", respectively. RESULTS: Apneas enhanced PNS-derived cardiac-modulation during REM in males, but more importantly, they made PNS-function unstable during both REM and NREM in males and during NREM in females. Aging blunted the PNS-derived cardiac-modulation during both REM and NREM regardless of gender, but aging had no impact on the stability of PNS-function. BMI blunted PNS-eliciting cardiac-modulation during REM in males and during NREM in both males and females. BMI made the PNS unstable during REM in females. Neither height nor cigarette consumption influenced any PNS-related parameter. CONCLUSIONS: The PNS-derived cardiac-modulation was generally inhibited by aging and obesity, in which the effect of obesity was gender-specific. The PNS instability at nighttime was mainly induced by apneas but by obesity particularly during REM in females.