Table 2.
Analysis of the relationships between PSG outcomes and BMI, lung volume, and IOS measurements in the sitting and supine positions
| RDI (events/h) | p-value (two-tailed) | BMI (kg/m2) | p-value (two-tailed) | |
|---|---|---|---|---|
| BMI, kg/m2 | 0.39 | 0 | - | - |
| Sitting position | ||||
| ERV, L | −0.221 | 0.001 | −0.178 | 0.009 |
| FRC, L | −0.141 | 0.042 | −0.176 | 0.010 |
| Rrs0, kPa · s · L−1 | 0.239 | 0.000 | 0.258 | 0.000 |
| Zrs5, kPa · s · L−1 | 0.230 | 0.001 | 0.257 | 0.000 |
| R5, kPa · s · L−1 | 0.217 | 0.001 | 0.255 | 0.000 |
| X5, kPa · s · L−1 | −0.379 | 0.000 | −0.308 | 0.000 |
| Grs, L · kPa−1 · s−1 | −0.240 | 0.000 | −0.260 | 0.000 |
| Gz, L · kPa−1 · s−1 | −0.230 | 0.001 | −0.257 | 0.000 |
| Supine position | ||||
| Rrs0, kPa · s · L−1 | 0.425 | 0.000 | 0.306 | 0.000 |
| Zrs5, kPa · s · L−1 | 0.395 | 0.000 | 0.289 | 0.000 |
| R5, kPa · s · L−1 | 0.378 | 0.000 | 0.298 | 0.000 |
| X5, kPa · s · L−1 | −0.517 | 0.000 | −0.322 | 0.000 |
| Grs, L · kPa−1 · s−1 | −0.425 | 0.000 | −0.305 | 0.000 |
| Gz, L · kPa−1 · s−1 | −0.395 | 0.000 | −0.290 | 0.000 |
Abbreviations: BMI body mass index, ERV expiratory reserve volume, FRC functional residual capacity, Rrs0 resistance at zero-frequency, Zrs5 respiratory impedance at 5 Hz, R5 respiratory resistance at 5 Hz, X5 respiratory reactance at 5 Hz, Grs respiratory conductance, the reciprocal of Rrs0, Gz the reciprocal of Zrs5. All values are Spearman’s rank correlation coefficients (r)