Combat Casualties Undergoing Lifesaving Interventions Have Decreased Heart Rate Complexity at Multiple Time Scales
ARMY INST OF SURGICAL RESEARCH FORT SAM HOUSTON TX
Pagination or Media Count:
We found that heart rate HR complexity metrics such as sample entropy SampEn identified patients with trauma receiving lifesaving interventions LSIs. We now aimed 1 to test a multiscale entropy MSE index, 2 to compare it to single scale measures including SampEn, and 3 to assess different parameter values for calculation of SampEn and MSE. This was a study of combat casualties in an emergency department in Iraq. Electrocardiograms of 70 acutely injured adults were recorded. Twelve underwent LSIs and 58 did not. Lifesaving interventions included endotracheal intubation 9, tube thoracostomy 9, and emergency transfusion 4. From each electrocardiogram, a segment of 800 consecutive beats was selected. Offline, R waves were detected and R to R interval time series were generated. Sample entropy, MSE, and time domain measures of HR variability mean HR, SD, the proportion of pairs of consecutive NN intervals that differ by more than 20 and 50 milliseconds, square root of the mean of the squares of differences between adjacent NN intervals were computed. Differences in mean HR LSI 111 or - 33, non LSI 90 or - 17 beatsmin were not significant. Systolicarterial pressure was statistically but not clinically different LSI 123 or - 19, non LSI 135 or - 19 mm Hg. Sample entropy LSI 0.90 or - 0.42, non LSI 1.19 or - 0.35 P less than .05 and MSE index LSI 2.58 or - 2.55, non LSI 5.67 or - 2.48 P less than .001 differed significantly. Complexity of HR dynamics over a range of time scales was lower in high risk than in low risk combat casualties and outperformed traditional vital signs.
- Medicine and Medical Research
- Weapons Effects (Biological)