Operation of wireless biopotential monitoring system

• US 20020045836A1
• Filed: 02/14/2001
• Published: 04/18/2002
• Est. Priority Date: 10/16/2000
• Status: Abandoned Application

• Current Assignee: International Thinking Machines Corporation
• Original Assignee: International Thinking Machines Corporation
• Inventors: Alkawwas, Dima
• Application Number:
  US09/783,471
• Publication Number:
  US 20020045836A1
• Time in Patent Office: Days
• US Class Current: 600/509
• CPC Class Codes: A61B 2560/0412 Low-profile patch shaped housings
• CPC Class Codes: A61B 2560/0468 Built-in electrodes
• CPC Class Codes: A61B 5/0006 ECG or EEG signals
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]

Abstract

Multiple wireless sensor assemblies are individually attached to standard body locations for EKG signal recording. The sensors measure small biopotential signals at short distances on the body sites, and the small signals are used to calculate an output signal that resembles a conventional EKG measurement signal over the long distance between the sensors. An algorithm is employed to calculate the standard EKG signal using the two measurement sites'"'"' data and an attenuation value between sensor contacts which has been previously measured.

Claims

1. A system of obtaining a calculated Lead I standard EKG measurement waveform from unconnected EKG sensors placed on a patient'"'"'s body, comprising:

a) a base station comprising a wireless transceiver for two-way communication with multiple individual, wireless sensors;

b) Right Arm and Left Arm individual unconnected wireless sensors constructed and arranged for establishing a communication with the base station, each sensor adapted for receiving electrical contacts;

the plurality of individual wireless sensors including;

ii. the Right Arm sensor having first and second input contacts defining a first line, with a voltage drop C, between the first sensor first and second input contacts; and

ii. the Left Arm sensor having first and second input contacts defining a second line, with a voltage drop, D, between the second sensor first and second input contacts;

c) whereby the Right Arm sensor first and second input contacts and the Left Arm sensor first and second input contacts define a quadrilateral when placed on a patient'"'"'s body with the first and second lines being two sides of the quadrilateral;

d) a third line and a fourth line of the quadrilateral being parallel;

e) the third line of the quadrilateral extending between the first sensor first contact and second sensor first contact and having an EKG voltage drop, A;

f) the fourth line of the quadrilateral extending between the first sensor second contact and second sensor second contact having an EKG voltage drop, B;

g) the sensors adapted to obtain and send a measurement of the C and D voltage drops to the base station, and

h) the base station adapted to receive the measurement of the C and D voltage drops from the sensors and calculate the EKG voltage drop B, representing Lead I, by using the measured C and D voltage drops and an attenuation value x, between the amplitude of A and the amplitude of B.

2. The system of claim 1 wherein the EKG voltage drop B is calculated by performing the calculation:

B=(C-D)/(1−

x), where (1−

x) is a calculated scaling factor.

3. The system of claim 2 wherein x=∥

A∥

/∥

B∥

, with ∥

A∥

being the norm value representing the length of a vector for A and ∥

B∥

being the norm value representing the length of the vector for B.

4. The system of claim 1 wherein the attenuation value x is obtained by taking conventional wired EKG voltage drop measurements of A and B, via a temporary hard wire connection and calculating the attenuation between the A and B EKG voltage drops to determine the attenuation value x, storing the attenuation value x in a memory of the base station and removing the hard wire connection.

5. The system of claim 1 further including a Left Leg unconnected EKG sensor adapted to be placed on the body in relation to the Right Arm and Left Arm EKG sensors for obtaining a Lead III EKG waveform,

wherein the Lead III EKG waveform is calculated from a first measurement of differential potential value between two input contacts of the Left Arm sensor and a second measurement of differential potential value between the two input contacts of the Left Leg sensor;

the second measurement being subtracted from the first measurement and the result of the subtraction being divided by a scaling factor, where the scaling factor includes an attenuation ratio value between two previously measured standard EKG measurement waveforms taken between the Left Arm and Left Leg sensors.

6. The system according to claim 5 wherein the Left Leg sensor has first and second input contacts and a third reference contact.

7. The system according to claim 5 wherein the two previously measured standard EKG measurement waveforms taken between the Left Arm and Left Leg sensors are a first measurement taken between the first input contacts of each of the Left Arm and Left Leg sensors, and a second measurement between the second input contacts of each of the Left Arm and Left Leg sensors.

8. The system of claim 5 further including:

the base station being adapted to calculate a Lead II EKG waveform value between the Right Arm sensor and the Left Leg sensor, wherein the Lead II EKG waveform value is calculated from the Lead I EKG waveform and the Lead III calculated EKG waveform as indicated by the following relationship;

Lead II= Lead I+ Lead III.

9. The system of claim 1 wherein the electrical contacts include two input contacts and a reference contact.

10. A system of obtaining a calculated standard biopotential measurement waveform from unconnected biopotential sensors adapted to be placed on a patient'"'"'s body, comprising:

a) a plurality of individual unconnected wireless sensors constructed and arranged for establishing wireless communication, each sensor having first and second electrical contacts;

the plurality of individual sensors including;

i. a first sensor having its first and second contacts defining a first line, with a voltage drop C, between the first sensor first and second contacts; and

ii. a second sensor having its first and second contacts defining a second line, with a voltage drop, D, between the second sensor first and second contacts;

b) whereby the first sensor first and second contacts and the second sensor first and second contacts define a quadrilateral when placed on a patient'"'"'s body with the first and second lines being two sides of the quadrilateral;

c) a third line and a fourth line of the quadrilateral being parallel;

d) the third line of the quadrilateral extending between the first sensor first contact and second sensor first contact and having a voltage drop, A;

e) the fourth line of the quadrilateral extending between the first sensor second contact and second sensor second contact having a voltage drop, B;

f) the sensors adapted to obtain a measurement of the C and D voltage drops;

g) each sensor adapted to communicate its respective C or D value to a data processing unit; and

h) the data processing unit adapted to receive the measurement of the C and D voltage drops from the sensors and calculate the voltage drop B, representing the desired standard biopotential measurement voltage drop, by using the measured C and D voltage drops and an attenuation value x.

11. The system of claim 10 wherein the voltage drop B is calculated by performing the calculation:

B=(C-D)/(1−

x).

12. The system of claim 11 wherein x=∥

A∥

/∥

B∥

, with ∥

A∥

being the norm value representing the length of a vector for A and ∥

B∥

being the norm value representing the length of the vector for B.

13. The system of claim 11 wherein (1−

x) is a calculated scaling factor between the amplitude of A and the amplitude of B.

14. The system of claim 13 further comprising a memory adapted for storing the scaling factor, the memory being in communication with the data processing unit.

15. The system of claim 10 wherein the attenuation value x is obtained by taking conventional wired biopotential signal measurements, via a temporary hard wire connection between the contacts of the third line, and a temporary hard wire connection between the contacts of the fourth line, and calculating the attenuation between the A and B voltage drops to determine the attenuation value x and removing the hard wire connection.

16. The system of claim 10 wherein the data acquisition of the sensors is simultaneous.

17. The system of claim 10 wherein the electrical contacts for at least one sensor include two input contacts and a reference contact.

19. The system of claim 18 wherein the scaling factor is 1 minus the attenuation ratio.

20. The system of claim 18 wherein each sensor has three electrical contacts, the three contacts including two input contacts and a reference contact.

18. A system of obtaining a calculated standard biopotential measurement waveform with first and second unconnected biopotential sensors placed on a patient'"'"'s body, wherein:

the standard biopotential measurement is calculated using a first measurement of differential potential value between two inputs of the first sensor and a second measurement of differential potential value between two inputs of the second sensor;

the second measurement being subtracted from the first measurement and the result of the subtraction being divided by a scaling factor, where the scaling factor includes an attenuation ratio between two previously measured standard biopotential measurement waveforms.

21. A system of obtaining a calculated standard biopotential measurement waveform from unconnected biopotential sensors placed on a patient'"'"'s body, comprising:

a) a base station comprising a wireless transceiver for two-way communication with multiple individual, wireless sensors;

b) a plurality of individual unconnected wireless sensors constructed and arranged for establishing a communication with the base station, each sensor adapted for receiving three electrical contacts including first and second input contacts and a reference contact;

the plurality of individual wireless sensors including;

i. a first sensor having its first and second input contacts defining a first line, with a biopotential signal C, between the first sensor first and second input contacts; and

ii. a second sensor having its first and second input contacts defining a second line, with a biopotential signal, D, between the second sensor first and second input contacts;

c) whereby the first sensor first and second input contacts and the second sensor first and second input contacts define a quadrilateral when placed on a patient'"'"'s body with the first and second lines being two sides of the quadrilateral;

d) the third line and the fourth line of the quadrilateral being parallel;

e) the third line of the quadrilateral extending between the first sensor first contact and second sensor first contact and having a biopotential signal, A;

f) the fourth line of the quadrilateral extending between the first sensor second contact and second sensor second contact having a biopotential signal, B;

g) the sensors adapted to obtain and send a measurement of the C and D biopotential signals to the base station, and

h) the base station adapted to receive the measurement of the C and D biopotential signals from the sensors and calculate the biopotential signal B, representing the desired standard biopotential measurement waveform, by using the measured C and D biopotential signals and an attenuation value x, between the amplitude of A and the amplitude of B.

22. The system of claim 21 wherein the voltage drop B is calculated by performing the calculation:

B=(C-D)/(1−

x).

23. The system of claim 21 wherein x=∥

A∥

/∥

B∥

, with ∥

A∥

being the norm value representing the length of a vector for A and ∥

B∥

being the norm value representing the length of the vector for B.

24. The system of claim 21 wherein the biopotential signal is a standard EKG Lead I signal, the first sensor is a Left Arm (LA) sensor and the second sensor is a Right Arm (RA) sensor.

25. The system of claim 21 wherein the attenuation value x is obtained by taking conventional wired biopotential signal measurements, via a temporary hard wire connection between the contacts of the third line, and a temporary hard wire connection between the contacts of the fourth line, and calculating the attenuation between the A and B biopotential signals to determine the attenuation value x, storing the attenuation value x in a memory of the base station and removing the hard wire connection.

26. The system of claim 21 further including a third unconnected biopotential sensor adapted to be placed on the body in relation to the first and second biopotential sensors for obtaining a second biopotential waveform,

wherein a second biopotential waveform is calculated from a first measurement of differential potential value between two inputs of the first sensor and a second measurement of differential potential value between two inputs of the third sensor;

the second measurement being subtracted from the first measurement and the result of the subtraction being divided by a scaling factor, where the scaling factor includes an attenuation ratio value between two previously measured standard biopotential measurement waveforms taken between the first and third sensors.

27. The system according to claim 26 wherein the third sensor has first and second input contacts and a third reference contact.

28. The system according to claim 26 wherein the two previously measured standard biopotential measurement waveforms taken between the first and third sensors are a first measurement taken between the first input contacts of each of the first and third sensors, and a second measurement between the second input contacts of each of the first and third sensors.

29. The system of claim 26 wherein the biopotential waveform is a standard EKG Lead III signal, the first sensor is a Left Ann (LA) sensor and the second sensor is a Left Leg (LL) sensor.

30. The system of claim 26 further including:

the base station being adapted to calculate a third biopotential waveform value between the second sensor and the third sensor, wherein the third biopotential waveform value is calculated from the first calculated biopotential waveform and the second calculated biopotential waveform as indicated by the following relationship;

third waveform value= first waveform value+ second waveform value.

31. The system of claim 30 wherein the third biopotential waveform is a standard EKG Lead II signal.