Bioimpedance System and Sensor and Technique for Using the Same

• US 20100081960A1
• Filed: 09/30/2008
• Published: 04/01/2010
• Est. Priority Date: 09/30/2008
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Nellcor Puritan Bennett LLC (Medtronic Plc)
• Inventors: McKenna, Edward M.
• Granted Patent: US 8,406,865 B2
• Time in Patent Office: Days
• US Class Current: 600/547
• CPC Class Codes: A61B 2562/0233 Special features of optical sensors or probes classified in A61B5/00
• CPC Class Codes: A61B 2562/043 in a linear array
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/4869 Determining body composition

Abstract

A sensor assembly and/or systems for bioimpedance measurements may provide information related to the lean body water of the patient'"'"'s tissue. The information related to the patient'"'"'s lean body water may be determined by spectroscopic methods for determining water fraction. The patient'"'"'s fat-free hydration levels may be incorporated into determinations of physiological parameters that may be determined by bioimpedance, such as cardiac output, hemtocrit, or body fat percentage.

Claims

1. A monitoring system comprising:

a storage device storing routines for;

receiving a bioimpedance signal from at least one bioimpedance sensor;

receiving a water fraction signal from at least one water fraction sensor;

determining a physiological parameter based at least in part on the bioimpedance signal and the water fraction signal; and

a processor capable of executing the stored routines.

2. The system as set forth in claim 1, wherein the physiological parameter comprises cardiac output, hematocrit, or body fat percentage.

3. The system as set forth in claim 1, wherein the storage device comprises one or more of a ROM, RAM, solid state storage device, optical medium, or magnetic medium.

4. The system as set forth in claim 1, wherein the water fraction signal is used to determine a hydration factor based on lean body water content.

5. The system as set forth in claim 4, wherein the hydration factor is used as part of an algorithm to determine the physiological parameter.

6. The system as set forth in claim 4, wherein the hydration factor is compared to one or more values in a stored look-up table to determine a corrected value of the physiological parameter.

7. The system as set forth in claim 1, comprising a sensor assembly capable of generating the bioimpedance signal and the water fraction signal.

8. The system as set forth in claim 7, wherein the sensor assembly comprises a plurality of electrodes.

9. The system as set forth in claim 7, wherein the sensor assembly, comprises an emitter and a detector.

10. A method, comprising:

receiving a bioimpedance signal;

receiving a water fraction signal; and

determining a physiological parameter based at least in part on the bioimpedance signal and the water fraction signal.

11. The method as set forth in claim 10, comprising determining a lean body water content based on the water fraction signal.

12. The method as set forth in claim 10, comprising determining a hydration factor based on the water fraction signal.

13. The method as set forth in claim 12, comparing the hydration factor to one or more values in a stored look-up table to determine a corrected value of the physiological parameter.

14. The method as set forth in claim 10, wherein determining the physiological parameter comprises determining one or more of cardiac output, hematocrit, or body fat percentage.

15. A sensor assembly comprising:

a plurality of electrodes disposed on a sensor body, wherein at least one of the electrodes is capable of generating a signal related to an impedance of a patient'"'"'s tissue; and

a water fraction sensor disposed on the sensor body, wherein the water fraction sensor comprises an emitter capable of emitting light into the patient'"'"'s tissue and a detector capable of detecting the light.

16. The sensor assembly as set forth in claim 15, wherein the plurality of electrodes comprise a dipole electrode patch.

17. The sensor assembly as set forth in claim 15, wherein the emitter is capable of emitting at least two different wavelengths of light.

18. The sensor assembly as set forth in claim 15, wherein the emitter is capable of emitting light having a wavelength between approximately 950-1400 nm, approximately 1500-1800 nm and/or approximately 2000-2300 nm.

19. The sensor assembly as set forth in claim 15, wherein the emitter and the detector are spaced between about 1 mm and about 5 mm apart on the sensor body.

20. The sensor assembly as set forth in claim 15, comprising one or more additional detectors at different respective distances from the emitter than the detector.