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Rheoencephalography: A non-invasive method for neuromonitoring

Sandor Szabo
Sandor Szabo
, 
Zsolt Totka
Zsolt Totka
, 
Jozsef Nagy-Bozsoky
Jozsef Nagy-Bozsoky
, 
Istvan Pinter
Istvan Pinter
, 
Mihaly Bagany
Mihaly Bagany
 e 
Michael Bodo
Michael Bodo
   | 13 mar 2024
Journal of Electrical Bioimpedance's Cover Image
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Pubblicato online: 13 mar 2024
Pagine: 10 - 25
Ricevuto: 07 dic 2023
DOI: https://doi.org/10.2478/joeb-2024-0003
Parole chiave
© 2024 Sandor Szabo et al., published by Sciendo
This work is licensed under the Creative Commons Attribution 4.0 International License.

Fig. 1:

Trace of REG signal with Silverlon electrodes with Cerberus amplifier. The time window is 33.125 sec. The Y axis is in volt; the X axis is in second.
Trace of REG signal with Silverlon electrodes with Cerberus amplifier. The time window is 33.125 sec. The Y axis is in volt; the X axis is in second.

Fig. 2:

Boxplot of bioimpedance pulse peak values in Silverlon and Velcro electrodes (n=14 peaks). The difference is significant (p =0.0052).
Boxplot of bioimpedance pulse peak values in Silverlon and Velcro electrodes (n=14 peaks). The difference is significant (p =0.0052).

Fig. 3:

Upper two traces: 10 Hz sinus ±1 V labeled as head and arm, imitating REG, and arm bioimpedance pulses. Channels are in phase on the left and right sides; in the middle, the head pulses were inverted indicated by minimal amplitude increase—lower trace: Pearson’s correlation coefficient calculation (PRx). The left side indicates passive CBF AR, value is +1. The first PRx number is 300 sec. During the phase inversion, the value changes to −1, indicating active CBF AR status.
Upper two traces: 10 Hz sinus ±1 V labeled as head and arm, imitating REG, and arm bioimpedance pulses. Channels are in phase on the left and right sides; in the middle, the head pulses were inverted indicated by minimal amplitude increase—lower trace: Pearson’s correlation coefficient calculation (PRx). The left side indicates passive CBF AR, value is +1. The first PRx number is 300 sec. During the phase inversion, the value changes to −1, indicating active CBF AR status.

Fig. 4:

The two 10 Hz sinus ±1 V waves imitating head and arm pulse waves. On the left side in phase. On the right side is the inverted portion. The phase inversion starts at 988.35 seconds - time window: 0.965 min.
The two 10 Hz sinus ±1 V waves imitating head and arm pulse waves. On the left side in phase. On the right side is the inverted portion. The phase inversion starts at 988.35 seconds - time window: 0.965 min.

Fig. 5:

Trace of bifrontal REG (upper trace) on a tilting table. BH indicates the breath holdings. Under its label are the blood pressure (systolic/diastolic) numbers. The middle traces are the REGx traces. The lower trace shows fragments of REG during breath-holding (left side) and transition from horizontal to HDT position (right side). Arrows indicate the location of magnified portions. The Y-axis is in Volt. The X-axis is in seconds. The window size is 2630 seconds, 43.83 min. The file name is April 26 1.
Trace of bifrontal REG (upper trace) on a tilting table. BH indicates the breath holdings. Under its label are the blood pressure (systolic/diastolic) numbers. The middle traces are the REGx traces. The lower trace shows fragments of REG during breath-holding (left side) and transition from horizontal to HDT position (right side). Arrows indicate the location of magnified portions. The Y-axis is in Volt. The X-axis is in seconds. The window size is 2630 seconds, 43.83 min. The file name is April 26 1.

Fig. 6:

Fragments of recording of bifrontal and bitemporal REG pulse waves during control/rest (before HDT position; 0o), on the left side) and during HDT positions (-15o) (on the right side) in four subjects. The color indicates derivation. The Y axis is in Volt. X axis is in seconds. The window size is about 3 sec. Subjects are labeled by the recording date, for example, 4.5.1: the first recording that day.
Fragments of recording of bifrontal and bitemporal REG pulse waves during control/rest (before HDT position; 0o), on the left side) and during HDT positions (-15o) (on the right side) in four subjects. The color indicates derivation. The Y axis is in Volt. X axis is in seconds. The window size is about 3 sec. Subjects are labeled by the recording date, for example, 4.5.1: the first recording that day.

Fig. 7:

Change of P2 amplitude of REG pulse waves in female (n=6; on the left) and in the male group (n=13; on the right) before (control/baseline; 0o) and during HDT position (–15o). P<0.0001 in both groups. 95% confidence interval −0.04123 to −0.02710 in the female group and −0.05796 to −0.05178 for males.
Change of P2 amplitude of REG pulse waves in female (n=6; on the left) and in the male group (n=13; on the right) before (control/baseline; 0o) and during HDT position (–15o). P<0.0001 in both groups. 95% confidence interval −0.04123 to −0.02710 in the female group and −0.05796 to −0.05178 for males.

Fig. 8:

Averages of male and female groups bifrontal REGx during rest and HDT position. The correlation coefficient is 0.49; the statistical significance is 0.03. Note the difference during HDT. During this period, the correlation coefficient is 0.21; the statistical significance is p=0.0002. REGx decreased at the start of HDT, indicating the active status of CBF AR.
Averages of male and female groups bifrontal REGx during rest and HDT position. The correlation coefficient is 0.49; the statistical significance is 0.03. Note the difference during HDT. During this period, the correlation coefficient is 0.21; the statistical significance is p=0.0002. REGx decreased at the start of HDT, indicating the active status of CBF AR.

Fig. 9:

Comparison of cerebrovascular reactivity measured by 3 methods for 30 seconds breath-holding (BH), hyperventilation (HV), and CO2 inhalation (n=10). The figure was created from study data [41].
Comparison of cerebrovascular reactivity measured by 3 methods for 30 seconds breath-holding (BH), hyperventilation (HV), and CO2 inhalation (n=10). The figure was created from study data [41].

REG P1 and P2 amplitudes (means of 5-10 pulse peak values) during control and HDT in four subjects, calculated from pulse waves presented in Fig. 6. The amplitude difference was calculated as a percentage of the control/baseline (BL%). REGx R2: correlation coefficient of bifrontal and bitemporal REGx during the full time of the recording. The sample traces are presented in Fig.6. Arm bioimpedance recordings were missing in the case of the 4.5.1 subject, consequently, there was no REGx calculation.

REG peak values and REGx correlation coefficients
P1 P2 P1 P2 REGx
April 5.1 R2
Control 0.43 0.35 0.47 0.37 N/A
HDT 0.42 0.59 0.47 0.58
BL% −0.33 36.32 26.27 57.97
April 11
Control 0.71 0.58 0.7 0.57 0.75
HDT 0.71 0.63 0.7 0.63
BL% −0.16 7.64 0.1 8.99
April 19.2
Control 0.77 0.67 0.73 0.67 0.65
HDT 0.73 0.73 0.7 0.67
BL% −4.74 8.91 −4.1 0.71
April 21.1
Control 0.81 0.66 0.81 0.67 0.55
HDT 0.78 0.74 0.76 0.77
BL% −2.89 12.01 −5.78 16.04
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