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Table 3 Comparison of the RR HF-CDM parameters between the two groups of patients (unstable vs stable) at PEEP 10.

From: Positive End-Expiratory Pressure may alter breathing cardiovascular variability and baroreflex gain in mechanically ventilated patients

RR series Parameters Unstable group (n = 11) Stable group (n = 12) p value
Raw RR mean value (ms) 777 (613-911) 551 (473-600) 0.004
HF-CDM amplitude mean value (ms) 3.04 (1.91-7.17) 1.33 (1.10-1.98) 0.007
  lnHF/RR (ms/s) 1.42 (0.80-2.18) 0.54 (0.15-1.28) 0.05
  SD (ms) 1.21 (0.81-2.03) 0.14 (0.09-0.30) 0.001
  time below thresholda (%) 8.37 (4.50-11.92) 0.00 (0.00-0.00) 0.001
HF-CDM phase SD (rad) 0.80 (0.35-2.42) 0.13 (0.08-0.22) 0.001
  maximal drift (rad) 2.76 (0.78-6.17) 0.44 (0.29-0.679) 0.001
  1. All results were reported as means ± SEM when normality has been checked, as median (25-75 percentile) values otherwise. a: percentage of time spent with HF amplitude below 50% of the mean HF amplitude for the individual patient. For each patient, the resulting parameter values were the average of the beat-to-beat values over the analysis period. Mean RR and HF amplitude were lower in the stable group. The two parameters related to the variability of HF amplitude (standard-deviation and time spent below the threshold of amplitude) were lower in this group, reflecting a more stable HF amplitude over time. The two parameters related to the variability of the HF-RR/ventilation phase difference (standard-deviation and maximal drifts) were lower in the stable group, reflecting a more stable RR/ventilation phase difference over time.