[Arousals from sleep in patients with obstructive disordered breathing: a comparison study for mechanisms]

Area of Science:

• Sleep Medicine
• Respiratory Physiology

Background:

• Excessive daytime sleepiness (EDS) is a common symptom in sleep disorders.
• Obstructive sleep apnea syndrome (OSAS) and upper airway resistance syndrome (UARS) are characterized by breathing disruptions during sleep.

Purpose of the Study:

• To investigate the primary triggers of respiratory arousal in patients with sleep-disordered breathing.
• To differentiate the causes of arousal in OSAS and UARS compared to healthy controls.

Main Methods:

• Nocturnal polysomnography (PSG) and respiratory inductive plethysmography were used to monitor 25 patients with EDS and 7 healthy controls.
• Patients were classified into OSAS (apnea/hypopnea index [AHI] ≥ 5/h) or UARS (Epworth Sleepiness Score ≥ 12, frequent inspiratory flow limitation, AHI < 5/h).

Main Results:

• Patients with OSAS had significantly higher AHI and time spent with oxygen saturation < 90% (SLT90%) compared to UARS and control groups.
• Despite similar AHI and SLT90% to controls, UARS patients exhibited an arousal index (ArI) as high as OSAS patients.
• The arousal index in UARS patients was comparable to that in OSAS patients, suggesting a different primary cause for arousal.

Conclusions:

• Inspiratory flow limitation appears to be the main driver of sleep arousals in patients with obstructive sleep-disordered breathing.
• Findings suggest that respiratory arousal in UARS is primarily linked to airflow resistance rather than apneas or oxygen desaturation events.
• This highlights the importance of addressing inspiratory flow limitation in the management of sleep-disordered breathing.