Heart period variability (FD-L) was associated with the need for lifesaving interventions (p=0.0004), but its 82% correct classification rate was only 2% higher than the baseline prediction rate.
Observational (n=159)
Does heart period variability provide added value in identifying the need for lifesaving interventions in prehospital trauma patients with normal standard vital signs?
Heart period variability has limited clinical utility for predicting the need for lifesaving interventions in prehospital trauma patients with normal vital signs due to high overlap between patient groups.
p-value: p=0.0004
OBJECTIVE: To determine whether heart period variability provides added value in identifying the need for lifesaving interventions (LSI) in individual trauma patients with normal standard vital signs upon early medical assessment. DESIGN: Retrospective database review. SETTING: Helicopter transport to Level 1 trauma center and first 24 hrs of in-hospital care. PATIENTS: Prehospital trauma patients requiring helicopter transport to Level 1 trauma center. MEASUREMENTS AND MAIN RESULTS: Heart period variability was analyzed from electrocardiographic recordings collected from 159 prehospital trauma patients with normal standard vital signs (32 LSI patients, 127 No-LSI patients). Although 13 of the electrocardiogram derived metrics demonstrated simple (i.e., univariate) discrimination between groups, at the multivariate level, only fractal dimension by curve length (FD-L) was uniquely associated with group membership (LSI vs. No-LSI, p = .0004). Whereas the area under the receiver operating characteristics curve for FD-L was 0.70, the overall correct classification rate (true positives and true negatives) of 82% was only 2% higher than the baseline prediction rate of 80% (i.e., no information except for the known proportion of overall No-LSI cases, 127 of 159 patients). Furthermore, 84% of the individual FD-L values for the LSI group were within the range of the No-LSI group. CONCLUSIONS: Only FD-L was uniquely able to distinguish patient groups based on mean values when standard vital signs were normal. However, the accuracy of FD-L in distinguishing between patients was only slightly better than the baseline prediction rate. There was also very high overlap of individual heart period variability values between groups, so many LSI patients could be incorrectly classified as not requiring an LSI if a single heart period variability value was used as a triage tool. Based on this analysis, heart period variability seems to have limited value for prediction of LSIs in prehospital trauma patients with normal standard vital signs.
Rickards et al. (Mon,) conducted a observational in Prehospital trauma (n=159). Heart period variability (fractal dimension by curve length) was evaluated on Need for lifesaving interventions (LSI) (p=0.0004). Heart period variability (FD-L) was associated with the need for lifesaving interventions (p=0.0004), but its 82% correct classification rate was only 2% higher than the baseline prediction rate.