Internal bleeding detection apparatus

• US 9,763,580 B2
• Filed: 05/16/2014
• Issued: 09/19/2017
• Est. Priority Date: 12/23/2005
• Status: Active Grant

• Current Assignee: E.I.T. Pty., Ltd.
• Original Assignee: E.I.T. Pty., Ltd.
• Inventors: Sadleir, Rosalind, Duncan, Andrew
• Primary Examiner(s): TOWA, RENE T
• Application Number:
  US14/279,361
• Publication Number:
  US 20140288405A1
• Time in Patent Office: 1,222 Days
• CPC Class Codes: A61B 5/0002 Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network A61B5/07 takes precedence; transmission systems for measured values G08C; transmission H04B; transmission of digital information H04L; wireless communication networks H04W
• CPC Class Codes: A61B 5/02042 Determining blood loss or bleeding, e.g. during a surgical procedure
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/0536 Impedance imaging, e.g. by tomography
• CPC Class Codes: A61B 5/0537 Measuring body composition by impedance, e.g. tissue hydration or fat content
• CPC Class Codes: A61B 5/6831 Straps, bands or harnesses

Abstract

An EIT system 1 adapted to detect internal bleeding in a body portion, the EIT system 1 comprising a plurality of electrodes 3 adapted in use to extend in a substantially linear orientation across one side only of the body portion and to be applied in electrical contact with the skin of the body portion, a current source adapted to cyclically apply an electric current between one pair of the electrodes 3, a voltage measuring means to measure the voltage across each of the other pairs of the electrodes resulting from the current, a data collection system 2 and a data analysis system 4 to analyze data resulting from the voltages that are measured by the voltage measuring means, wherein the analysis system 4 is configured to obtain quantitative information related to amounts and rates of conductive tissue changes occurring in the body, based on an EIT analysis equivalent to that obtained from data derived from electrodes spaced around the full perimeter of the body portion. Also disclosed is an electrode belt suitable for bioelectrical use and in particular for detection of change of volume of tissue in a body portion.

Claims

1. A method for detecting changes in tissue volume using an EIT system, the method comprising the steps of:

providing a belt having a core layer, a insulating layer on either side of the core layer, a shielding layer on either side of each of the insulating layer, and an outer layer on either side of each the shielding layer, wherein the core layer comprises a plurality of spaced apart electrodes to be applied in electrical contact with the surface of a body portion, wherein the insulating layers expose only one side of the electrodes, wherein each shielding layer comprises a conductive material providing circumferential shielding for the belt, wherein one of the outer layers includes a plurality of apertures corresponding to said electrodes to provide engagement of only one side of the electrodes on the surface of the body portion;

applying a current between a pair of the electrodes of the belt;

measuring, at predetermined intervals, and at a multiplicity of locations in a plane through the body portion, the voltage between the pairs of electrodes at the surface of the body portion resulting from the applied current to provide a set of voltage measurements;

determining the changes of the voltage measurement between consecutive sets of voltage measurements;

generating a reconstructed image of the body portion;

determining a resistivity index of the tissue within the body portion from the reconstructed image;

deriving a volume of tissue from the determined resistivity index;

determining the rate of change of tissue volume between consecutive sets of voltage measurements.

2. A method for detecting changes in tissue volume as claimed in claim 1 wherein the method includes the further step of initiating an alarm where the rate of change of issue volume is above a predetermined value.

3. A method for detecting changes in tissue volume as claimed in claim 1 wherein the resistivity index is calculated by generating a vector indicative of the changes in voltage measurements between consecutive sets of voltage measurements;

and multiplying the vector by a reconstruction matrix, the resultant matrix being the reconstructed image.

4. A method for detecting changes in tissue volume as claimed in claim 1 wherein the resistivity index is calculated by integrating pixel values from the reconstructed image.

5. An apparatus for detecting changes in tissue volume and its rate of change by EIT analysis comprising:

first processing means;

second processing means; and

electrode means adapted to apply a predetermined current between a pair of electrodes spaced at the surface of a body portion, under control of the first and second processing means and also adapted to measure in a plane through the body portion, the voltage between pairs of electrodes at the surface of the body portion resulting from the applied current to provide a set of voltage measurements, wherein the electrodes extend in a substantially linear orientation across one side only of the body portion;

wherein the electrode means comprises a belt having a core layer, a insulating layer on either side of the core layer, a shielding layer on either side of each of the insulating layer, and an outer layer on either side of each the shielding layer, wherein the core layer comprises a plurality of spaced apart electrodes to be applied in electrical contact with the surface of the body portion, wherein the insulating layers expose only one side of the electrodes, wherein each shielding layer comprises a conductive material providing circumferential shielding for the belt, wherein one of the outer layers includes a plurality of apertures corresponding to said electrodes to provide engagement of only one side of the electrodes on the surface of the body portion; and

the first processing means being operable to receive the set of measured voltages and to provide the set of voltage measurements to the second processing means, the first processing means being further operable to receive set of voltage measurements at predetermined intervals and to provide these sets to the second processing means, the second processing means being operable to determine the changes of the voltage measurement between consecutive sets of voltage measurements;

to provide a reconstructed image of the body portion;

to determine the resistivity index of the tissue from the reconstructed image;

to derive a volume of tissue from the determined resistivity index; and

to determine the rate of change of tissue volume between consecutive sets of voltage measurements.

6. An apparatus for detecting changes in tissue volume as claimed in claim 5 wherein the first processing means is further operable to measure voltage noise levels.

7. An apparatus for detecting changes in tissue volume as claimed in claim 5 wherein the second processing means is further operable to initiate an alarm where the rate of change of tissue volume is above a predetermined value.

8. An apparatus for detecting changes in tissue volume as claimed in claim 5 wherein the second processing means is operable to determine the resistivity index by calculating a vector indicative of changes in voltage measurements between consecutive sets of voltage measurements;

multiplying the vector by a reconstruction matrix, the resultant matrix being the reconstructed image.

9. An apparatus for detecting changes in tissue volume as claimed in claim 8 wherein the resistivity index is generated by integrating the pixels or voxels in the reconstructed image.

10. An apparatus for detecting changes in tissue volume as claimed claim 5, whereby current can be applied to any pair of the multiplicity of electrodes, and the voltage measured from one or more pairs of the multiplicity of electrodes.

11. An apparatus for detecting changes in tissue volume as claimed in claim 5 wherein the first processing means is operable to apply current to all pairs of electrodes on the belt, and to take voltage measurements from all possible pairs of electrodes, for each current electrode pair.

12. An apparatus for detecting changes in tissue volume as claimed claim 5 wherein the second processing means is provided remote from the first processing means.

13. An apparatus for detecting changes in tissue volume as claimed in claim 5 wherein the current is sequentially applied to all pairs of electrodes on the belt, and voltage measurements are measured from all possible pairs of electrodes, for each current electrode pair.