White Paper

EIS White paper

EIS Performances :

The EIS provides an electrical signal corresponding to the status of a patient's physiological parameters: Na+/K+ATPase pump activity, tissue pCO2, sympathetic system activity and microcirculation blood flow.

Background

A DC current , very low frequency (1Hz) current and low frequency (from 700 Hz to 1 KHz ) current are applied between six tactile electrodes placed symmetrically on the forehead, hands, and feet of the subject. Each electrode is alternatively cathode and anode (bipolar mode from anode to cathode), which permits the records of 22 segments (2816 pulses in 2 minutes) from the human body in multi frequencies (measurement sequence according to the figure 1). The measured resistance's (Ohm law) are transmitted with a

numeric scale for each segment to an informative program

The resistance's are converting to conductivities (C = 1/R), incorporated in a Graph. The graph of the conductivities of the 22 segments is called an Electro Scan Gram (E.S.G) for each frequency (Figure 2).

Figure 2

Normal range of ESG conductivity
The normal ranges of conductivity of the ESG graph (Figure 3) were estimated with the statistical analysis raw data's of healthy control groups of the pre-studies, clinical investigations and users’ databases.

Figure 3

Technologies:

The used technologies are the Bio Impedance technologies in bipolar mode, Signal Processing analysis and Modeling process .

1. Bio Impedance Technologies

The Electrode Polarization Impedance (EPI),

The electrical Bio Impedance Analysis (BIA),

Bio Impedance Plethysmography (BIP)

The Galvanic Skin Responses (GSR)

The EPI (1Hz) is used for in vivo estimation of Na+/K+APTase pump activity .

The BIA (700 Hz) is used for in vivo estimation of tissue pCo2

The BIP (1 KHz) is used for in vivo estimation of the microcirculation Blood flow.

The GSR (DC) is used for the stress evaluation and provides estimation of the sympathetic system activity and emotional arousal.

2. EIS system Signal Processing Analysis :

What is the Signal Processing Analysis?

Steps of the EIS Signal Processing Analysis:

Step 1 :Entire records of the EIS measurement (2816 pulses)

Figure 4

Conversion of the ESG to Second Derivative ESG (SDESG)

Figure 5

The SD ESG is a mathematical calculation to convert a graph with a scale 0-100 to a graph from 100 to minus 100.

The mathematical calculation of the standard deviation of the conductivities of the SDESG to the normal range provides the Na+/K+ATPase pump activity.

Step 2. Each 22 measured segments signal is analyzing : The stability of each segment signal (32 pulses) analysis provides the estimation of the tissue pCO2 (negative delata) and microcirculation vasoconstriction (positive delta).

Figure 6

Step 3. The Spectrum analysis and the Application of the Discrete Fast Fourier Transform to the entire records (2816 pulses) provides a frequencies graphic where:

HF corresponding to the estimation of the cells exchange activity.

LF no interpretation

VLF :Oxygen available

HF/VLF corresponding to the estimation of the Oxygen uptake/Oxygen available ratio

HF/LF corresponding to the microcirculation necessary/ microcirculation blood flow ratio .

Figure 7

3. Modeling Technology

Why and What a modeling?

At present, the treatment plans made by doctors rely on predictions based on statistical averages. The physiology of the human body is complex and individual, but advanced computational methods enable the modeling of the body. Designing a reliable model requires accurate information about the functioning and anatomy of the body and about the properties of tissues. Advances in computing power enable utilization of quite complex models in the daily work of doctors. As the possibilities of treating diseases improve, it is important to choose the right treatment for each individual patient. Today, a doctor may be able to use a virtual model to test how the planned treatment would affect a patient, and can choose the best treatment method in each individual’s case. The challenge faced by models is how to apply them to a patient’s personal physiological characteristics. Some Medical models are already used in fields that are easy to model.

EIS modeling process

The EIS modeling process is related with the Analysis of the ESG graph in domain analysis with the following steps:

Scale conversion : EIS conversion from the scale 0-100 to -100/+100 (step1)

Venn diagram (step2)

Maxwell equation (step3)

Color code (step 4)

The modeling of the EIS system is made according to a color code from blue to red related to the tissue pCO2 .

Diagram of the process of EIS modeling:

Figure 8

Verification and Validation of the EIS Modeling

From problem to the solution: 6 steps in 9 years

Figure 9