Impact of posture and CPAP on nasal airflow.

Obstructive sleep apnea (OSA) patients who use continuous positive airway pressure (CPAP) often complain of nasal dryness and nasal obstruction as side effects of CPAP. The physiological mechanisms by which CPAP may cause nasal dryness and nasal obstruction remain poorly understood. It has been hypothesized that CPAP interferes with the nasal cycle, abolishing the resting phase of the cycle and leading to nasal dryness. We performed rhinomanometry measurements in 31 OSA patients sitting, laid supine, and supine after 10 min of CPAP at 10 cmH2O. A posture change from sitting to supine led to more symmetric airflow partitioning between the left and right nostrils in the supine position. CPAP did not have a significant impact on nasal resistance, unilateral airflows, or airflow partitioning. Our results suggest that airflow partitioning becomes more symmetric immediately after changing to a supine position, while CPAP had no effect on nasal airflow, thus preserving the nearly symmetric airflow partitioning achieved after the posture change.

Characteristics of rapid eye movement-related obstructive sleep apnea in Thai patients.

Obstructive sleep apnea (OSA) is a common sleep disorder that has been associated with cardiovascular consequences. Rapid eye movement (REM)-related obstructive sleep apnea (OSA) is a subtype of OSA which is characterized by apneas or hypopneas predominately during REM sleep. The factors associated with REM-related OSA are still unclear. We aimed to determine the prevalence and associated characteristics of REM-related OSA in Thai patients. A total of 408 patients' charts were retrospectively reviewed. Demographic and anthropometric characteristics, comorbidities and polysomnographic data were obtained. The patients were divided into two groups: REM-related OSA and non-stage specific OSA. REM-related OSA was defined as an apnea-hypopnea index (AHI) ≥ 5 per hour, with a ratio of REM-AHI to NREM-AHI > 2, and NREM-AHI < 15 per hour. The prevalence of REM-related OSA was 21.6%. AHI and arousal index were both lower in REM-related OSA than in non-stage specific OSA. REM-related OSA was significantly associated with females (OR 2.35, 95% CI 1.25-4.42, p = 0.008), age < 60 years (OR 2.52, 95% CI 1.15-5.55, p = 0.021), and mild OSA (OR 17.46, 95% CI 9.28-32.84, p < 0.001). In conclusion, age < 60 years, female gender, and mild severity of OSA were associated with REM-related OSA.