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Table 3 Means and standard deviations of 30 ECG waveform features in 4 lying positions

From: Lying position classification based on ECG waveform and random forest during sleep in healthy people

Lying positions Left Supine Right Prone
QT 442.234 ± 4.763 434.916 ± 4.907 439.099 ± 5.361 427.654
QTc 446.541 ± 11.936 448.476 ± 10.903 453.259 ± 10.506 440.679
RR 985.050 ± 15.378 946.057 ± 17.053 942.002 ± 16.838 944.844
PR inter 139.201 ± 3.113 139.811 ± 3.233 139.574 ± 2.526 164.698
PR segment 21.708 ± 3.162 24.096 ± 2.731 23.382 ± 2.766 58.389
ST inter 341.285 ± 8.573 331.296 ± 8.029 327.401 ± 8.539 352.817
ST segment 77.024 ± 10.596 71.534 ± 9.446 71.020 ± 8.098 86.649
P wide 117.493 ± 2.397 115.715 ± 2.548 116.192 ± 2.580 106.308
QS wide 65.397 ± 2.820 70.183 ± 2.684 73.107 ± 2.848 54.014
T wide 264.261 ± 5.653 259.763 ± 4.260 256.381 ± 5.765 266.168
TP segment 382.120 ± 9.830 350.049 ± 11.086 342.160 ± 9.964 330.975
P peak 0.138 ± 1.414 0.233 ± 2.303 0.222 ± 1.739 0.112
R peak 1.808 ± 11.290 2.428 ± 16.243 2.291 ± 10.299 1.184
S peak 0.655 ± 4.970 0.533 ± 5.212 0.551 ± 3.110 0.206
T peak 0.547 ± 2.812 0.776 ± 3.427 0.696 ± 3.662 0.553
QRS area 266.365 ± 108.806 389.564 ± 158.961 387.565 ± 144.974 179.905
T area 165.776 ± 59.467 228.880 ± 67.021 200.339 ± 74.594 139.677
Ta/QRSa 1.129 ± 0.365 1.153 ± 0.381 0.848 ± 0.361 1.036
QRSa–Ta 100.588 ± 81.630 160.684 ± 120.856 187.226 ± 123.533 40.228
Rp-Tp x 301.607 ± 4.836 294.935 ± 4.940 295.938 ± 5.479 296.884
Rp-Tp y 21.477 ± 10.474 28.500 ± 15.368 27.279 ± 9.478 11.814
Tp-te 116.747 ± 1.705 115.795 ± 1.878 118.661 ± 2.742 108.543
QR 3.228 ± 18.543 4.661 ± 30.424 4.431 ± 20.729 2.678
RS 2.463 ± 14.825 2.961 ± 18.830 2.841 ± 12.079 1.390
RT slope 0.361 ± 0.185 0.489 ± 0.267 0.472 ± 0.180 0.199
RS slope 5.142 ± 2.698 5.600 ± 3.576 5.106 ± 3.137 3.527
ST slope1 0.106 ± 0.097 0.116 ± 0.108 0.080 ± 0.039 − 0.028
S/R 0.365 ± 0.151 0.232 ± 0.154 0.258 ± 0.122 0.174
T/R 0.245 ± 0.177 0.242 ± 0.090 0.220 ± 0.100 0.336
Angle qsr 106.798 ± 29.477 126.956 ± 25.830 127.175 ± 24.154 127.711
  1. In this table, the time-limit features are calculated in millisecond (ms), the amplitude features are calculated in millivolt (mV), and the angle indicator is calculated in degree. Due to the fact that most subjects did not have prone, or only had several prone epochs in overnight sleep, the standard deviations of features in prone were not shown in this table