Table 5 Polysomnographic and spectrographic metrics across apnea severity groups (mean ± SD)
From: Distinct polysomnographic and ECG-spectrographic phenotypes embedded within obstructive sleep apnea
Polysomnographic variable | Mild (n = 70) | Moderate (n = 394) | Severe (n = 320) | Extreme (n = 188) |
 Total Sleep Time (minutes) | 386 ± 68 | 376 ± 64 | 388 ± 63 | 368 ± 74 |
 Sleep efficiency % TST | 80.9 ± 13.3 | 79 ± 12.8 | 80.1 ± 11.1 | 76.4 ± 14.2 |
 Arousal index/hour of sleep | 14.2 ± 10.4 | 19.8 ± 12.1 | 29 ± 15.3 | 53.9 ± 28.6 |
 S1 % TST | 11.4 ± 7.9 | 14 ± 8.4 | 18.1 ± 11.2 | 30.6 ± 22.5 |
 S2 % TST | 63.6 ± 8.4 | 62.6 ± 9.7 | 60.6 ± 11 | 53.7 ± 20.9 |
 S3 + S4 % TST | 5.5 ± 7.2 | 4 ± 6.7 | 3 ± 5.4 | 1.7 ± 4.3 |
 REM % TST | 19.4 ± 6.6 | 19.2 ± 6.5 | 18.2 ± 6.8 | 13.9 ± 7.2 |
 RDI/hour of sleep | 5.5 ± 2.7 | 19.1 ± 5.8 | 44 ± 8.7 | 83.6 ± 17.6 |
 CAI/hour of sleep | 0.8 ± 0.2 | 0.3 ± 1 | 1.2 ± 3 | 3.2 ± 9.3 |
 Minimum SaO2 | 87.7 ± 11.5 | 84.8 ± 5.1 | 79.7 ± 7.5 | 72.7 ± 10.6 |
ECG-spectrographic variable | n = 54 | n = 296 | n = 209 | n = 112 |
 HFC % TST | 50.8 ± 19.6 | 44.5 ± 21 | 36.9 ± 20.8 | 22.1 ± 19.7 |
 LFC % TST | 29.4 ± 13.8 | 35.7 ± 16.2 | 45.6 ± 17.8 | 62.8 ± 21 |
 e-LFC % TST | 11.1 ± 10.1 | 15.3 ± 11.5 | 22.3 ± 16.2 | 37.3 ± 25.2 |
 e-LFCNB % TST | 0.02 ± 0.07 | 1.2 ± 2.7 | 3.8 ± 8.5 | 9.9 ± 13.3 |
 VLFC % TST | 17.6 ± 7.1 | 17.6 ± 7.4 | 15.2 ± 6.9 | 12.9 ± 6.9 |