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Table 2 Analysis of the relationships between PSG outcomes and BMI, lung volume, and IOS measurements in the sitting and supine positions

From: Receiver operating characteristics of impulse oscillometry parameters for predicting obstructive sleep apnea in preobese and obese snorers

  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
  1. 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)