Ultra-short heart rate variability reliability for cardiac autonomic tone assessment in severe traumatic brain injury

Abstract

This study compares heart rate variability (HRV) indices across different time epochs (5 minutes, 1 minute, and 30 seconds) to evaluate the reliability of ultra-short recordings for assessing cardiac autonomic tone 1 year after a severe traumatic brain injury (TBI). Electrocardiogram recordings were obtained from 48 patients 1 year after a severe TBI. Pearson correlation analysis was performed to evaluate the association between ultra-short HRV indices (1 minute and 30 seconds) and the standard 5-minute recordings. Additionally, ANOVA was used to compare the differences in mean HRV indices across the different epochs. The correlation analysis supports that time-domain indices present higher correlation coefficients (r = 0.63 to 0.99, p < 0.05) when compared with frequency-domain indices (r = 0.51 to 0.97, p < 0.05). The reduction in recording time increases the percentage variation of all indices. The root mean square of the successive differences of RR intervals (rMSSD) shows higher Pearson coefficient values and lower percentage variation at the 1-minute and 30-second epochs compared with other HRV indices. Ultra-short HRV indices are reliable for assessing cardiac autonomic tone in chronic patients who survived severe TBI. rMSSD was the most reliable HRV index for ultra-short recordings. The value of ultra-short HRV for cardiovascular prognosis after severe TBI remains to be determined in future studies.