Glossopharyngeal airway collapse is the main factor leading REM-related oxygen desaturation in patients with...

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

All subjects underwent overnight polysomnography with synchronous genioglossus electromyography using intraoral surface 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). The ratio of REM-OD/NREM-OD ≥ 1.5 was defined as patients with REM-related OD. The upper airway anatomy was measured by three-dimensional computed tomography (3D-CT) in all subjects. The independent t test was used to analyze the difference between groups.

Thirty-three male OSA patients were recruited and divided into two groups, includingthe REM-related OD group (n = 15, AHI 68.01 ± 18.35 events/h) and the NREM-related OD group (n = 18, AHI 57.48 ± 28.81 events/h). The REM-related OD group 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 = 0.020) and smaller minimal cross-sectional airway area (119.81 ± 30.94 vs. 199.78 ± 75.02, p = 0.005).

Glossopharyngeal airway narrowing is the leading factor of REM-related OD in paitients with moderate or severe OSA by the prolongation of apnea events during REM sleep.