Differentiation of autonomic nervous activity in different stages of coma displayed by power spectrum analysis of heart rate variability

Abstract

The analysis of heart rate (HR) variability offers a noninvasive method to investigate autonomic nervous system activity in comatose patients. We analyzed three components of the HR variability in a group of comatose patients: the low-frequency band (LF), representing mainly sympathetic influence, the mid-frequency band (MF), representing sympathetic and parasympathetic influence, and the high-frequency band (HF), representing the parasympathetic influence. A value for sympathovagal balance was defined as LF/HF and MF/HF ratio. Moreover, the skin conductance level (SCL) and the skin conductance resistance (SCR) variability were recorded. The patient group consisted of 22 patients with traumatic brain injuries. Coma depth was assessed by the Glacow Coma Scale and artifact-free HR, SCL, and SCR were measured 75 times in the patient group. The results documented a significant gain in sympathetic nervous system activity corresponding with the state of emerging from coma. This gain was most pronounced in the HF component of the HR and in the sympathovagal balance between LF/HF. The findings in SCL and SCR variability endorsed this result. It is concluded that emerging from coma is accompanied by an increasing influence of the sympathetic nervous system on HR control. This leads to a change in the sympathovagal balance, i.e., a reintegration of parasympathetic and sympathetic activity.

Autonomic impairment of patients in coma with different Glasgow coma score assessed with heart rate variability

“…It has been shown that the ANS functional state predicts responsiveness in disorders of consciousness [5]. Multiple indices of HRV calculated in the time, frequency or informational domains have been studied in patients in coma with different objectives: to assess brainstem dysfunction [6], to assess brain death [7][8][9], differentiation of autonomic nervous activity in different stages of coma [10], diagnosis of dysautonomia after traumatic brain injuries (TBI) [11], calculation and description of HRV indices of patients in coma [12] correlation of the HRV parameters with the Glasgow coma score (GCS) [13][14][15][16], prediction or prognosis of the outcome in TBI, acute cerebral vascular disease, or critically ill neurosurgical patients [17][18][19][20][21][22][23], association of HRV indices with mortality in patients with TBI [24][25][26][27][28][29][30][31][32], and prediction of life saving interventions in patients with trauma [22,[33][34][35][36][37].…”

Continuous electrodermal activity as a potential novel neurophysiological biomarker of prognosis after cardiac arrest – A pilot study

“…More recently, a study assessing autonomic nervous system activity in comatose patients after severe traumatic brain injury demonstrated that awakening from coma was associated with higher SCL and a higher variability in phasic responses. 9 All 22 patients were sedated and received analgesia, as in our study. Finally, a group evaluated difference in skin conductance responses after a neutral and an emotional stimuli in 13 comatose patients (including 8 from brain anoxia) and 20 healthy volunteers.…”

“…Older studies have shown that some EDA parameters reflect depth of coma. [8][9][10] Until recently, EDA recordings allowed for only short-term recordings, 7 moreover they were difficult to obtain in comatose patients. 8 with conductive fabric electrodes rather than gel-based Ag/AgCl electrodes, has recently been developed.…”

The Trace Conditional Learning of the Noxious Stimulus in UWS Patients and Its Prognostic Value in a GSR and HRV Entropy Study

“…Several studies highlight the potential of measuring the GSR following auditory (Hildebrandt et al, 1998;Keller et al, 2007;Dolce et al, 2008) or nociceptive stimuli in DOC patients (Venturella, 2018). Notwithstanding, these measures were not used in a systematic way to explore the pain perception in these patients.…”