Long-term HRV metrics may assist in differentiating between prolonged disorders of consciousness and emergence from minimally conscious state : a cross-sectional study

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Abstract
Diagnosing prolonged disorders of consciousness (DoC) remains a significant challenge in neurorehabilitation. Heart rate variability (HRV), a noninvasive measure of cardiac autonomic regulation, has been increasingly recognized as relevant to the mechanisms underlying consciousness. However, long-term HRV data in DoC patients remain scarce. This study aimed to investigate the relationship between long-term HRV metrics and the severity of consciousness impairment in patients with prolonged DoC. In this cross-sectional study, 49 patients with prolonged DoC were enrolled. Each participant underwent five assessments using the Coma Recovery Scale-Revised (CRS-R) and one 24-hour electrocardiographic (ECG) monitoring session within one week of enrollment. Based on their highest CRS-R subscale scores, patients were categorized into three groups: unresponsive wakefulness syndrome (UWS, n = 17), minimally conscious state (MCS, n = 19), and emergence from MCS (EMCS, n = 13). HRV time-domain and frequency-domain indices were extracted from the 24-hour ECG recordings. Differences in HRV metrics among the consciousness groups were analyzed, and correlations between HRV parameters and CRS-R scores were examined. Significant differences in HRV metrics were observed among the three consciousness groups (P < 0.05), including both time-domain indices (SDNN, SDANN, SDNN Index) and frequency-domain indices (HF, LF, VLF, ULF, and Total power). Furthermore, these HRV indices were significantly correlated with CRS-R scores (P < 0.05), indicating a strong association between autonomic function and the level of consciousness. Long-term HRV monitoring reveals significantly greater heart rate variability in EMCS patients compared to those in UWS and MCS, highlighting its potential utility as a supplementary biomarker for assessing consciousness in patients with prolonged DoC.
Funding Information
  • Key Supporting Discipline Construction Project of Shanghai Health System (No. 2023ZDFC0304)
  • Shanghai Science and Technology Innovation Action Plan (No. 20412420200)
  • Shanghai Municipal Key Clinical Specialty (No. shslczdzk02702)
  • Shanghai Zhou Liangfu Medical Development Foundation “Brain Science and Brain Diseases Youth Innovation Program
  • Hongyu Xie, National Key R&D Program of China (No. 2018YFC2001700)
  • the key projects of Shanghai Science and Technology on Biomedicine (22Y31900202)

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