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Studies in Rheoencephalography (REG) Cover

Studies in Rheoencephalography (REG)

Journal of Electrical Bioimpedance
Volume 1 (2010): Issue 1 (January 2010)
By: Michael Bodo  
Open Access
|Apr 2010

Figures & Tables

Fig.1

Arterial pressure waveform (red) REG waveform (blue). Figure illustrates the inverse relationship between the systemic arterial blood pressure (femoral artery) and the raw REG signal: impedance is decreased when tissue is filled with blood. The peak difference, indicated by two vertical bars, is about 60 msec.
Arterial pressure waveform (red) REG waveform (blue). Figure illustrates the inverse relationship between the systemic arterial blood pressure (femoral artery) and the raw REG signal: impedance is decreased when tissue is filled with blood. The peak difference, indicated by two vertical bars, is about 60 msec.

Fig.2

Block schematics of in vitro measurement: pump flow rate change caused flow change.
Block schematics of in vitro measurement: pump flow rate change caused flow change.

Fig.3

Traces with low pump flow (Part A) and higher flow rate (Part B). Variables in part A were: pressure: 119.57 mmHg, Mean flow: 68.08 mL/min; circulatory resistance (pressure/flow): 1.75. Variables in part B were: pressure: 116.13 mmHg, Mean flow: 124.98 mL/min; circulatory resistance (pressure/flow): 0.93. These variables are mean values, were calculated using 20 seconds of recording with DataLyser software, also showing traces as they can be seen with same software.
Traces with low pump flow (Part A) and higher flow rate (Part B). Variables in part A were: pressure: 119.57 mmHg, Mean flow: 68.08 mL/min; circulatory resistance (pressure/flow): 1.75. Variables in part B were: pressure: 116.13 mmHg, Mean flow: 124.98 mL/min; circulatory resistance (pressure/flow): 0.93. These variables are mean values, were calculated using 20 seconds of recording with DataLyser software, also showing traces as they can be seen with same software.

Fig.4

Traces with low pump flow (part A) and higher flow rate (part B). The first derivative of pressure and impedance showed amplitude change corresponding to increased flow (Part B).
Traces with low pump flow (part A) and higher flow rate (part B). The first derivative of pressure and impedance showed amplitude change corresponding to increased flow (Part B).

Fig.5

Impedance measuring cell for balloon inflation
Impedance measuring cell for balloon inflation

Fig.6

Effect of balloon inflation on Doppler flow and electrical impedance pulse amplitudes.
Effect of balloon inflation on Doppler flow and electrical impedance pulse amplitudes.

Fig.7

Signal for data processing with various amplitudes. Arrows indicate the start of processed five second signals. Y axis is in Volts (left side); X axis is in seconds.
Signal for data processing with various amplitudes. Arrows indicate the start of processed five second signals. Y axis is in Volts (left side); X axis is in seconds.

Fig.8

REG pulse amplitude increases during CO2 inhalation (subgroup A). Filtered REG: after removal of the respiratory subharmonic, Carotid L and R: left and right carotid arterial flow, SAP: systemic arterial pressure, CO2: exhaled carbon dioxide and at the arrow: 10 % inhaled CO2 during 1 s. Time window: 60 s. The rat/file ID was: 157 – 3.
REG pulse amplitude increases during CO2 inhalation (subgroup A). Filtered REG: after removal of the respiratory subharmonic, Carotid L and R: left and right carotid arterial flow, SAP: systemic arterial pressure, CO2: exhaled carbon dioxide and at the arrow: 10 % inhaled CO2 during 1 s. Time window: 60 s. The rat/file ID was: 157 – 3.

Fig.9

Effect of clamping of common carotid arteries.
Effect of clamping of common carotid arteries.

Fig.10

Increase in intracranial REG (iREG) pulse amplitude during hemorrhage. Time window: 23.9 minutes. Carotid flow decreased similarly to SAP without showing any sign of CBF AR. REG amplitude transiently increased then decreased, suggesting CBF AR and indicating a lower limit before 40 mmHg SAP.
Increase in intracranial REG (iREG) pulse amplitude during hemorrhage. Time window: 23.9 minutes. Carotid flow decreased similarly to SAP without showing any sign of CBF AR. REG amplitude transiently increased then decreased, suggesting CBF AR and indicating a lower limit before 40 mmHg SAP.

Fig.11

SD was elicited by ICP elevation. ICP elevation caused SD shown as amplitude fluctuation of DC EEG trace. REG showed close identical fluctuation.
SD was elicited by ICP elevation. ICP elevation caused SD shown as amplitude fluctuation of DC EEG trace. REG showed close identical fluctuation.

Fig. 12

Dorsal view of rat skull with electrode localization.
Dorsal view of rat skull with electrode localization.

Fig.13

ICP elevation by balloon inflation and saline infusion; REG was measured by Minnesota Impedance Cardiograph. Z0 decreased during balloon inflation and increased during saline injection. REG first derivative (dZ/dt) was increased in both cases. Time window is 10 minutes. dZ/dt was previously filtered as was described in the method section.
ICP elevation by balloon inflation and saline infusion; REG was measured by Minnesota Impedance Cardiograph. Z0 decreased during balloon inflation and increased during saline injection. REG first derivative (dZ/dt) was increased in both cases. Time window is 10 minutes. dZ/dt was previously filtered as was described in the method section.

Fig.14

Typical changes during vinpocetine bolus injection: SAP decreased, ICP elevated and REG pulse amplitudes increased. REG was filtered as described in methods session. Time window: 180 seconds. File: 2009 Oct 2 -2 (4020-4200 s).
Typical changes during vinpocetine bolus injection: SAP decreased, ICP elevated and REG pulse amplitudes increased. REG was filtered as described in methods session. Time window: 180 seconds. File: 2009 Oct 2 -2 (4020-4200 s).

Fig.15

Comparison of CBF AR: Effect of 20 cm H20 PEEP before and after hemorrhage. Before hemorrhage (upper panel); Hemodynamic status: SAP 120/78; mean 92 mmHg; CBF AR present since SAP decrease elicited increase in CF and REG pulse amplitudes. After hemorrhage (lower panel; blood loss of ~1.3 L with estimated SBV of 30%); hemodynamic status: SAP 90/67; mean 75 mmHg. CBF AR impaired since SAP decrease elicited decrease in CF and REG pulse amplitudes.
Comparison of CBF AR: Effect of 20 cm H20 PEEP before and after hemorrhage. Before hemorrhage (upper panel); Hemodynamic status: SAP 120/78; mean 92 mmHg; CBF AR present since SAP decrease elicited increase in CF and REG pulse amplitudes. After hemorrhage (lower panel; blood loss of ~1.3 L with estimated SBV of 30%); hemodynamic status: SAP 90/67; mean 75 mmHg. CBF AR impaired since SAP decrease elicited decrease in CF and REG pulse amplitudes.

Fig.16

Correlation between REG and carotid flow pulse amplitude changes in PEEP group.
Correlation between REG and carotid flow pulse amplitude changes in PEEP group.

Fig.17

Relationship of REG to systemic arterial pressure during lethal hemorrhage. The shape of this relationship strongly suggests that the REG signal is reflecting the cerebral vasodilation that occurs over the range of SAP from 90 to 50 mm Hg. The negative Pearson coefficient indicates the presence of autoregulation in this range and a positive Pearson coefficient below 50 mm Hg indicates the absence of autoregulation.
Relationship of REG to systemic arterial pressure during lethal hemorrhage. The shape of this relationship strongly suggests that the REG signal is reflecting the cerebral vasodilation that occurs over the range of SAP from 90 to 50 mm Hg. The negative Pearson coefficient indicates the presence of autoregulation in this range and a positive Pearson coefficient below 50 mm Hg indicates the absence of autoregulation.

Fig.18

Sorted age and REG. Age and REG regression data (calculated as one group, n=13) are as follow: Age: y = 3.4505x + 11.769, R2 = 0.9509, and REG: 1.7912x + 50.385, R2 = 0.9527 (both linear).
Sorted age and REG. Age and REG regression data (calculated as one group, n=13) are as follow: Age: y = 3.4505x + 11.769, R2 = 0.9509, and REG: 1.7912x + 50.385, R2 = 0.9527 (both linear).

Fig.19

REG and EEG electrodes in electrode cap (left) and peripheral electrodes (right).
REG and EEG electrodes in electrode cap (left) and peripheral electrodes (right).

Fig.20

Cerberus traces on left and right side (ECG is the same on both side); Redirec screen [65].
Cerberus traces on left and right side (ECG is the same on both side); Redirec screen [65].

Fig.21

Significant correlations among measured variables. Cerebrovascular alteration (REG-Doppler-TIA) was in a bridge position between measured somatic (left) and psychological (right) variables (n=546, p<0.05). Legend: SAP: systemic arterial pressure; cer. art. scler: cerebral arteriosclerosis; REG: rheoencepha-logram; Doppler: carotid flow systolic velocity measured by Doppler ultrasound; veget. bal: vegetative balance by Kerdo–Sipos; cholest: blood level of total cholesterol; TIA: symptoms of transient ischemic attack entered into Cerberus inquiry.
Significant correlations among measured variables. Cerebrovascular alteration (REG-Doppler-TIA) was in a bridge position between measured somatic (left) and psychological (right) variables (n=546, p<0.05). Legend: SAP: systemic arterial pressure; cer. art. scler: cerebral arteriosclerosis; REG: rheoencepha-logram; Doppler: carotid flow systolic velocity measured by Doppler ultrasound; veget. bal: vegetative balance by Kerdo–Sipos; cholest: blood level of total cholesterol; TIA: symptoms of transient ischemic attack entered into Cerberus inquiry.

Fig.22

Comparison of slope of age regression lines (REG anacrotic time and Doppler systolic velocity). REG anacrotic time (Y axis in ms: REG anacrotic rise time) and Doppler systolic flow velocity (Y axis not shown) of internal carotid artery are plotted as a function of age (X axis). The regression lines of male and female groups are similar, but the slope of REG is about ten times steeper than that of the Doppler curve. f: female, m: male. Reprinted courtesy of Health Quest Publications Anti-Aging Medical Therapeutics, Vol. II. [38].
Comparison of slope of age regression lines (REG anacrotic time and Doppler systolic velocity). REG anacrotic time (Y axis in ms: REG anacrotic rise time) and Doppler systolic flow velocity (Y axis not shown) of internal carotid artery are plotted as a function of age (X axis). The regression lines of male and female groups are similar, but the slope of REG is about ten times steeper than that of the Doppler curve. f: female, m: male. Reprinted courtesy of Health Quest Publications Anti-Aging Medical Therapeutics, Vol. II. [38].

Fig.23

Typical REG curve of a healthy (normal) and a sclerotic person. Note the difference in peak time of REG curves for normal patients (92 milliseconds) and sclerotic patients (256 milliseconds). This difference has pathological meaning, independent of heart rate. Reprinted courtesy of Health Quest Publications Anti-Aging Medical Therapeutics, Vol. II [38].
Typical REG curve of a healthy (normal) and a sclerotic person. Note the difference in peak time of REG curves for normal patients (92 milliseconds) and sclerotic patients (256 milliseconds). This difference has pathological meaning, independent of heart rate. Reprinted courtesy of Health Quest Publications Anti-Aging Medical Therapeutics, Vol. II [38].

Summary of REG studies (1975-2010) and REG devices used_ Legend: Metal fragment study involved in vitro and in vivo measurements_ Several hundred Cerberus measurements were excluded from this list since there was no data processing and/or Medline accessible publication_ Spreading dep: depression; * Challenges were: 30 sec breath holding, hyperventilation, CO2 inhalation, Valsalva maneuver, Trendelenburg, inverted Trendelenburg position, and Exer-Rest shaking [59]_

GroupIn vitroSpeciesN/trialREGReference
CO2 inhalationhuman6Galileo32, 33
City screeninghuman140Medicor34
Rural screeninghuman564Cerberus35-41
Reproducibilityhuman13/130Cerberus42
Psychiatric patientshuman101Cerberus43,44
Radio frequencyhuman76/760Cerberus45
CBF tests*human4/24Cerberus
ICP increasecat6Galileo32,33,46
ICP increasedog6Galileo32,33,46
Brain electro-stimrat8UFI47
Aortic compressionpig1/4Galileo47
CO2/O2 inhalationrat16/84Medicor, Galileo, UFI47,48
Microwaverat40/200Medicor49-52
Carotid clampingrat5/13Galileo48
Hemorrhagerat14Galileo53
Liposome infusionpig24/57Galileo54
Hemorrhage, PEEPpig55/152Galileo55
Metal fragment+rat12/92Galileo, Cerberus56
Flow/volume+Galileo, Cerberus57
Spreading deprat1/4Galileo55
Hemorrhagemonkey8Cerberus55
Hypotensionpiglet17Galileo58
Vinpocetine ICP/NaClrat rat12/70 2/7Galileo, Cerberus MIC, Galileo
Subtotalhuman904/1725
Subtotalanimal227/742
Total1131/2467

Numeric characteristics of REG anacrotic time and age_ REG samples were analyzed dividing into subgroups according to age: young (17-28) and old (42-55)_ * p-values of difference between young and old group_

youngold
AgeREGAgeREG
yearmsyearms
Mean22,3365,5047,5760,71
SD4,378,344,585,65
Count6677
p>0,0001*0,0001*

Comparison of 5 types of data processing by their regression lines_ Correlation coefficient (R2) represents the strength of relationship between independent variable (Voltage) and dependent variables 1-5; intercept was set to 0_0; Hjorth A: activity, represents amplitude_

yR2
1. SD0.3035x1
2. RMS0.3055x0.9993
3. Variance0.1435x0.824
4. Hjorth A0.141x0.8093
5. FFT0.0343x0.7847

Comparison of Doppler flow and electrical impedance during low and high flow rates_ The effects of increased flow rate were comparable between Doppler and Impedance when the impedance derivations were calculated_

DOI: https://doi.org/10.5617/jeb.109 | Journal eISSN: 1891-5469
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Language: English
Page range: 18 - 40
Submitted on: Dec 10, 2009
Published on: Apr 1, 2010
Published by: University of Oslo
In partnership with: Paradigm Publishing Services
Publication frequency: 1 issue per year
Keywords:
Rheoencephalography,
carotid flow,
intracranial pressure,
cerebral blood flow autoregulation,
neuro-monitoring,
REG data processing,
arteriosclerosis,
expert system
Related subjects:
Engineering,
Bioengineering and biomedical engineering,
Biomedical electronics,
Life sciences,
Biophysics,
Medicine,
Biomedical engineering,
Physics,
Spectroscopy and metrology

© 2010 Michael Bodo, published by University of Oslo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

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