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Table 2 Univariate analysis of heart rate variability and complexity indices in associations with the need for life-saving interventions (LSI) amongst trauma patients

From: Development of a heart rate variability and complexity model in predicting the need for life-saving interventions amongst trauma patients

  LSI (n = 49) Non-LSI (n = 176) P value
Heart rate variability time domain analysis
 aRR (mean ± SD) 704.58 ± 166.48 746.76 ± 141.49 0.302
 sdRR (mean ± SD) 30.86 ± 31.20 34.71 ± 28.55 0.982
 avHR (median, IQR) 97.33, 85.59–122.96 88.96, 83.47–96.40 0.029
 sdHR (median, IQR) 2.03, 1.71–3.32 3.08, 1.88–4.53 0.899
 RMSSD (mean ± SD) 17.03 ± 26.46 35.12 ± 148.41 0.278
 NN50 (median, IQR) 0.00, 0.00–2.00 0.00, 0.00–13.75 0.043
 pNN50 (median, IQR) 0.00, 0.00–0.45 0.00, 0.00–3.85 0.051
 TINN (mean ± SD) 122.56 ± 93.47 150.75 ± 137.51 0.399
Heart rate variability frequency domain analysis
 VLF (median, IQR) 58.50, 41.75–218.25 243.00, 132.00–396.00 0.416
 LF ms2 (median, IQR) 15.50, 3.00–217.00 100.00, 60.00–262.00 0.072
 HF ms2 (median, IQR) 4.50, 0.75–25.00 44.00, 21.00–167.00 0.011
 LF norm (median, IQR) 89.05, 67.98–92.90 78.00, 50.30–84.00 0.128
 HF norm (median, IQR) 10.95, 7.03–31.98 21.00, 16.00–49.30 0.128
 LF/HF (median, IQR) 8.11, 3.32–13.26 4.52, 1.02–5.62 0.147
 TP (median, IQR) 76.00, 46.50–504.25 454.00, 275.00–713.00 0.175
Heart rate complexity non-linear analysis
 Poincare plot SD1(mean ± SD) 12.01 ± 18.76 17.49 ± 25.03 0.257
 Poincare plot SD2 (mean ± SD) 41.34 ±  40.65 43.42 ±  31.65 0.545
 Approximate entropy (mean ± SD) 1.00 ± 0.25 1.09 ± 0.15 0.001
 Sample entropy (mean ± SD) 1.13 ± 0.45 1.39 ± 0.38 0.144
 DFA-α1 (mean ± SD) 1.24 ± 0.39 1.12 ± 0.31 0.045
 DFA-α2 (median, IQR) 1.09, 0.93–1.68 1.00, 0.89–1.11 0.027
  1. IQR interquartile range, SD standard deviation, aRR average width of the RR intervals in electrocardiograms, sdRR standard deviation of all RR intervals in electrocardiograms, avHR mean of the instantaneous heart rate in electrocardiograms, sdHR standard deviation of the instantaneous heart rate in electrocardiograms, RMSSD root mean square of differences between adjacent RR intervals in electrocardiograms, NN50 number of consecutive RR intervals differing by more than 50 ms in electrocardiograms, pNN50 percentage of consecutive RR intervals differing by more than 50 ms in electrocardiograms, TINN baseline width of a triangle fit into the RR interval histogram using a least squares technique in electrocardiograms, VLF very low frequency power in electrocardiograms, LF low frequency power in electrocardiograms, HF high frequency power in electrocardiograms, norm normalised, LF/HF ratio of LF power to HF power in electrocardiograms, TP total power derived from variance of all RR intervals in electrocardiograms, DFA detrended fluctuation analysis