Does Heart-Rate Complexity Analysis Work In The Real World? Changes In The Point Correlation Dimension Of The Heart Rate During Prehospital Life-Saving Interventions

Objectives: The heart-rate time series is nonstationary and may contain noise and ectopy, jeopardizing traditional heart-rate variability (HRV) methods. Point Correlation Dimension (PD2i), a complexity-based HRV algorithm, measures time-dependent nonstationary changes in the degrees of freedom of cardiovascular regulation, and is reportedly less affected by these issues. Prior data suggest PD2i min min to distinguish trauma patients receiving life-saving interventions (LSIs) from those who did not. Methods: ECGs of varying lengths (mean 21.0 min, range 2.7 to 81.1 min) from 325 prehospital trauma patients were analyzed. First, the entire unedited ECG (“Raw”) was used for PD2i min calculation. Then, PD2i min was also calculated on manually verified, noise-and ectopy-free, 200-beat-long sections of ECG (“Clean”) selected from within the Raw files. Study endpoints were association of PD2i min with LSIs and death. LSIs included: intubation, CPR, chest tube, cricothyroidotomy. Results: Raw and Clean results corresponded well in the critical cut-off range of PD2i min ≤1 (Figure). Conclusions: Analysis of complex HRV via PD2i identifies trauma patients with good sensitivity; results are similar with Raw or manually edited Clean ECGs. Prospective studies of automated trauma triage using PD2i are planned.