Glossopharyngeal Airway Collapse Is the Main Factor Leading REM-Related Oxygen Desaturation in Patients with Obstructive Sleep Apnea

Introduction: This study aimed to determine the factors underlying rapid eye movement (REM) sleep-related oxygen desaturation (OD) in patients with obstructive sleep apnea (OSA).

Methods: All subjects underwent overnight polysomnography with synchronous genioglossus electromyography (GGEMG) using intraoral electrodes. For those subjects diagnosed with moderate or severe OSA (AHI >15 events/h), we respectively calculated the average OD during rapid eye movement (REM-OD) and non-rapid eye movement sleep (NREM-OD). Taking the ratio of REM-OD/NREM-OD ≥1.5 to define the patients with REM-related OD. The upper airway anatomy was measured by three-dimensional computed tomography (3D-CT) in all subjects.

Results: Comparing the REM-related OD group (n=10, AHI 68.01±18.35 events/h) to the NREM-related OD group (n = 12, AHI 57.48 ± 28.81 events/h), the former had a more severe lowest oxygen saturation overnight (56.14 ± 7.06 vs. 70.92 ± 14.49, p = 0.009). GGEMG variables were similar between the two groups, except for apnea time in the REM period (p < 0.001). Parameters measured by 3D-CT of the UA showed that the REM-related OD group had a narrower glossopharyngeal airway, with a smaller minimal anteroposterior airway dimension (12.41 ± 2.99 vs 17.58 ± 4.78, p = 0.02) and smaller minimal cross-sectional airway area (119.81 ± 30.94 vs 199.78 ± 75.02, p = 0.005).

Conclusions: REM-related OD in OSA patients is closely associated with glossopharyngeal airway narrowing, which is the leading factor in the prolongation of apnea events during REM sleep, while the contribution of genioglossus myoelectric activity to this mechanism is not obvious.