Long-term outcomes regarding arterial stiffness and carotid artery atherosclerosis in female patients with rapid eye movement obstructive sleep apnea.

OBJECTIVE: Rapid eye movement (REM) obstructive sleep apnea (OSA) is associated with the risk of cardiovascular events. Arterial stiffness and carotid artery intima-media thickness (IMT) predict these events, but few relevant studies have been conducted. We compared long-term changes in arterial stiffness and IMT between patients with REM OSA and non-REM (NREM) OSA receiving continuous positive airway pressure (CPAP) or oral appliance (OA) therapy. METHODS: Newly diagnosed female patients with OSA received CPAP (n = 6) or OA (n = 7). Pulse wave velocity (PWV) and carotid artery ultrasound were performed before and 60 months after treatment. RESULTS: There were no differences in baseline characteristics (mean age: 56.0 vs. 61.3 years; mean body mass index: 22.6 vs. 21.7 kg/m2) between the REM OSA and non-REM OSA groups. The median apnea-hypopnea index was lower in the REM OSA group than in the non-REM OSA group. Increased PWV (12.92 ± 1.64 to 14.56 ± 2.73 m/s) and deteriorated glucose metabolism were observed in the REM OSA group after treatment. PWV, IMT, and cardiovascular risk factors were unaffected in the non-REM OSA group. CONCLUSION: Arterial stiffness and glucose metabolism are deteriorated in patients with REM OSA compared with these parameters in patients with non-REM OSA after CPAP or OA treatment.

Efficacy of oral myofunctional therapy in middle-aged to elderly patients with obstructive sleep apnoea treated with continuous positive airway pressure.

BACKGROUND: Oral myofunctional therapy (MFT) is an effective treatment for mild-to-moderate obstructive sleep apnoea (OSA) in middle-aged patients. However, few reports have described its use in elderly patients with moderate and severe OSA. Moreover, no studies have examined the relationship between changes in tongue pressure with MFT and the severity of OSA. OBJECTIVE: We conducted an interventional study using MFT to evaluate the effect of MFT on middle-to-senior-aged patients with moderate or severe OSA and compared changes in apnoea-hypopnea index (AHI) and tongue pressure. METHODS: Thirty-two OSA patients (≥45 years) treated with continuous positive airway pressure (CPAP) were included. MFT was performed in parallel with CPAP. Three days after CPAP discontinuation, polysomnographies were performed and tongue pressures were measured before and after MFT. RESULTS: Patients were 69.3 ± 1.5 years old. After 6 months of MFT, AHI decreased significantly from 34.7 to 29.0/h (P = .03), while tongue pressure significantly increased from 35.9 to 45.6 kPa (P < .01). Seven patients (22%), including 6 of the 12 patients with moderate OSA (50%), experienced successful CPAP discontinuation. CONCLUSIONS: MFT can be a useful intervention even among middle-aged to elderly patients with OSA. Increased tongue pressure may have contributed to the AHI improvement. Clinical trials: Trial registration at www.umin.ac.jp UMIN000027547.

Arousal index as a marker of carotid artery atherosclerosis in patients with obstructive sleep apnea syndrome.

PURPOSE: It was shown in a previous cohort study that men with internal carotid artery (ICA) plaque, defined as focal wall thickness of ≥ 1.5 mm, had a threefold higher risk of stroke than those without plaque. We examined the relationship between arousal indices and sleep stages in patients with obstructive sleep apnea syndrome (OSAS) and carotid atherosclerosis. METHODS: Carotid atherosclerosis severity was evaluated using the maximal carotid wall intima-media thickness of the ICA (ICA-maxIMT) and plaque in 83 patients with OSAS. RESULTS: The ICA-maxIMT values were positively correlated with the apnea hypopnea index (AHI) (ρ = 0.294, P = 0.007), arousal index (ρ = 0.289, P = 0.008), oxygen desaturation index (ρ = 0.298, P = 0.006), percentage of visually scored total sleep time spent in nocturnal oxygen saturation < 90% (SpO2 < 90%) (ρ = 0.246, P = 0.025), and the percentage of visually scored total sleep time spent in non-REM sleep stage 1 (ρ = 0.326, P = 0.003) and were negatively correlated with the percentage of visually scored total sleep time spent in non-REM sleep stages 2 and 3. Arousal index, diabetes mellitus, and age were found to be independent predictors of ICA plaque presence (OR 1.052, P = 0.003; OR 8.705, P = 0.026; OR 1.064, P = 0.023, respectively). CONCLUSIONS: Several PSG variables that are indicative of sleep fragmentation, sleep disordered breathing, and poor sleep quality correlated with the occurrence of atherosclerosis, but total arousal index was the only independent predictive factor.

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.

Estimation of parasympathetic nerve function during sleep in patients with obstructive sleep apnea by instantaneous time-frequency analysis.

BACKGROUND AND OBJECTIVES: The pathophysiologic aspects of parasympathetic nerve (PN) function during sleep in patients with obstructive sleep apnea (OSA) studied by classical power spectrum analysis on heart rate variability (HRV) are highly controversial. The controversy is attributed to methodologic concerns, such as poor time resolution involved in power spectrum analysis. We aimed to establish the appropriate method for the investigation of PN function in OSA patients with apneas and hypopneas using instantaneous time-frequency analysis with complex demodulation (CD) and sufficient time resolution. METHODS: A total of 30 patients with PSG-confirmed mild to severe OSA were recruited for the analysis of frequency spectra contained in R-R intervals (RRI) of overnight electrocardiograph (ECG) tracings. High-frequency (HF) domains ranging between 0.15 and 0.40 Hz were selected for analysis. Among these domains, the HF domain with the maximum instantaneous amplitude was defined as the main HF peak and was used as the surrogate marker of PN discharge. Based on density spectrum array (DSA) map for main HF peak constructed with a time scale of 1s and a frequency resolution of 0.002 Hz (HF-DSA map), the shift in central frequency (CF) of main HF peak over time was continuously monitored. When the main HF peak with the same CF lasted for more than 20 s or 5 min on HF-DSA map, the PN function was considered to be stable or very stable. The measurements were then repeated after continuous positive airway pressure (CPAP) treatment. RESULTS: The extent of PN-evoked modulation of RRI was enhanced in nonrapid eye movement (NREM) sleep, though the stability was reduced in both NREM and rapid eye movement (REM) sleep. These peculiar behaviors of PN function were reversed by CPAP treatment. CONCLUSION: We found that instantaneous time-frequency analysis allowed estimation of transitional changes in PN function during sleep in OSA patients.