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. 2024 Nov 25;10(6):00255-2024. doi: 10.1183/23120541.00255-2024

TABLE 4.

Univariate correlations between anthropomorphic, spirometric and oscillometry parameters and supine hyperinflation as measured by supine IC/TLC ratio and the change in IC/TLC from the seated to supine position

COPD (n=41) Control (n=14)
Supine IC/TLC# Change in IC/TLC Supine IC/TLC Change in IC/TLC
rs p-value rs p-value rs p-value rs p-value
Age (years) 0.321 0.041 0.096 0.545 −0.17 0.562 −0.099 0.736
BMI (kg·m−2) 0.341 0.029 0.061 0.704 0.420 0.137 0.127 0.664
FEV1 (L) 0.674 <0.001 0.254 0.104 0.429 0.126 0.597 0.048
FEV1 (Z-score) 0.587 <0.001 0.090 0.575 0.437 0.118 0.358 0.208
FEV1/FVC 0.603 <0.001 0.266 0.08 0.178 0.542 0.180 0.537
FEV1/FVC (Z-score) 0.504 0.001 0.012 0.939 0.0284 0.326 0.442 0.114
RV/TLC −0.803 <0.001 −0.11 0.495 −0.899 <0.001 −0.614 0.02
RV/TLC (Z-score) −0.557 <0.001 −0.201 0.221 −0.824 <0.001 −0.424 0.131
Rrs5 (cmH2O·L−1·s−1) −0.227 0.153 −0.245 0.118 0.407 0.15 −0.042 0.887
Rrs5 (Z-score) −0.282 0.074 0.014 0.930 −0.169 0.563 −0.367 0.197
Xrs5 (cmH2O·L−1·s−1) 0.499 0.001 0.268 0.086 0.0857 0.773 0.460 0.098
Xrs5 (Z-score) 0.405 0.009 −0.090 0.578 0.424 0.131 0.073 0.805
ΔXrs5 (cmH2O·L−1·s−1) −0.413 0.007 −0.18 0.252 −0.275 0.341 0.398 0.158
Supine ΔXrs5 (cmH2O·L−1·s−1) −0.465 0.002 −0.239 0.127 −0.279 0.333 0.0484 0.869
Change in Rrs5 −0.091 0.574 0.17 0.274 0.35 0.22 0.396 0.16
Change in Xrs5 0.107 0.505 0.02 0.899 −0.231 0.427 0.022 0.94

Bold indicates statistical significance. rs: Spearman correlation coefficient; Rrs5: respiratory resistance at 5 Hz; Xrs5: respiratory reactance at 5 Hz; ΔXrs5: difference between inspiratory and expiratory reactance during tidal volume breathing; change in Rrs5 and Xrs5: changes in Z-scores between upright and supine posture; IC: inspiratory capacity; TLC: total lung capacity; BMI: body mass index; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; RV: residual volume. #: in the COPD cohort, there was little difference between mean seated and supine IC/TLC and therefore similar relationships were seen in the seated parameter.