SYSTEM AND METHOD FOR DETECTING FLUID RESPONSIVENESS OF A PATIENT

• US 20150265196A1
• Filed: 06/03/2015
• Published: 09/24/2015
• Est. Priority Date: 08/22/2012
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Su, Mark, Watson, James Nicholas, Addison, Paul Stanley
• Granted Patent: US 9,402,573 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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 5/02007 Evaluating blood vessel condition, e.g. elasticity, compliance
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61B 5/026 Measuring blood flow A61B3/1233, A61B3/1241 take precedence
• CPC Class Codes: A61B 5/0261 using optical means, e.g. infrared light
• CPC Class Codes: A61B 5/0295 using plethysmography, i.e. measuring the variations in the volume of a body part as modified by the circulation of blood therethrough, e.g. impedance plethysmography
• CPC Class Codes: A61B 5/0507 using microwaves or terahertz waves
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/1495 Calibrating or testing of in-vivo probes
• CPC Class Codes: A61B 5/333 Recording apparatus specially adapted therefor
• CPC Class Codes: A61B 5/4839 combined with drug delivery
• CPC Class Codes: A61B 5/486 Bio-feedback A61B5/375 takes precedence
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/7214 using signal cancellation, e.g. based on input of two identical physiological sensors spaced apart, or based on two signals derived from the same sensor, for different optical wavelengths
• CPC Class Codes: A61B 5/7225 Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation A61B5/30, A61B5/316 take precedence; transformers for specific applications H01F38/00; amplifiers H03F
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence
• CPC Class Codes: A61B 5/742 using visual displays A61B5/339 takes precedence
• CPC Class Codes: A61B 6/507 for determination of haemodynamic parameters, e.g. perfusion CT
• CPC Class Codes: A61B 8/06 : Measuring blood flow measuring volume flow in general G01F, e.g. G01F1/66, G01F1/72; measuring speed of fluids in general G01P5/00

Abstract

A system is configured to determine a fluid responsiveness index of a patient from a physiological signal. The system may include a sensor configured to be secured to an anatomical portion of the patient, and a monitor operatively connected to the sensor. The sensor is configured to sense a physiological characteristic of the patient. The monitor is configured to receive a physiological signal from the sensor. The monitor may include an index-determining module configured to determine the fluid responsiveness index through formation of a ratio of one or both of amplitude or frequency modulation of the physiological signal to baseline modulation of the physiological signal.

Claims

1. A medical monitor for determining a fluid responsiveness index of a subject, the monitor comprising:

an electrical input to receive a physiological signal from a sensor;

a processor configured to;

determine a value indicative of fluid responsiveness based on modulations of the physiological signal;

determine a value indicative of changes in vascular tone of the subject based on one or more metrics of the physiological signal; and

determine a fluid responsiveness index of the subject based on the value indicative of fluid responsiveness and the value indicative of changes in vascular tone.

2. The monitor of claim 1, wherein the one or more metrics comprise a relative amplitude ratio of the physiological signal.

3. The monitor of claim 1, wherein the one or more metrics comprise a width of at least one primary peak of the physiological signal.

4. The monitor of claim 1, wherein the one or more metrics comprise a time difference between at least one primary peak of the physiological signal and a trailing peak of the physiological signal.

5. The monitor of claim 1, wherein the one or more metrics comprise a pleth modulation ratio of the physiological signal.

6. The monitor of claim 1, wherein the processor is configured to determine the fluid responsiveness index of the subject by normalizing the value indicative of fluid responsiveness based on the value indicative of changes in vascular tone of the subject.

7. The monitor of claim 1, wherein the monitor comprise a pulse oximetry monitor, wherein the physiological signal comprises a photoplethysmogram (PPG) signal, and wherein the sensor comprises a pulse oximetry sensor.

8. The monitor of claim 7, wherein the one or more metrics comprise at least one of a relative amplitude ratio of the PPG signal, a width of at least one primary peak of the PPG signal, a time difference between at least one primary peak of the physiological signal and a trailing peak of the PPG signal, and a pleth modulation ratio of the PPG signal.

9. The monitor of claim 1, further comprising a fluid delivery device operatively connected to the monitor, wherein the monitor determines whether or not to administer fluid to the subject from the fluid delivery device based on the fluid responsiveness index.

10. The monitor of claim 1, further comprising a display operatively connected to the processor, wherein the processor is further configured to output a prompt to the display regarding whether or not to administer fluid to the subject, based on the fluid responsiveness index.

11. A method for determining a fluid responsiveness index of a subject from a physiological signal, the method comprising:

receiving a photoplethysmograph (PPG) signal from a pulse oximetry sensor at a pulse oximetry monitor;

determining, using the pulse oximetry monitor, a fluid responsiveness value based on the PPG signal;

determining, using the pulse oximetry monitor, a value indicative of changes in vascular tone of the subject based on the PPG signal; and

determining, using the pulse oximetry monitor, a fluid responsiveness index of the subject based on the fluid responsiveness value and the value indicative of changes in vascular tone of the subject.

12. The method of claim 11, wherein the value indicative of changes in vascular tone of the subject comprises at least one of a relative amplitude ratio of the PPG signal, a width of at least one primary peak of the PPG signal, a time difference between at least one primary peak of the physiological signal and a trailing peak of the PPG signal, and a pleth modulation ratio of the PPG signal.

13. The method of claim 11, wherein the value indicative of changes in vascular tone comprises a relative amplitude ratio of the PPG signal.

14. The method of claim 11, wherein the value indicative of changes in vascular tone comprises a width of at least one primary peak of the PPG signal.

15. The method of claim 11, wherein the value indicative of changes in vascular tone comprises a time difference between at least one primary peak of the physiological signal and a trailing peak of the PPG signal.

16. The method of claim 11, wherein the value indicative of changes in vascular tone comprises a pleth modulation ratio of the PPG signal.

17. The method of claim 11, wherein determining, using the pulse oximetry monitor, the fluid responsiveness index of the subject based on the fluid responsiveness value and the value indicative of changes in vascular tone of the subject comprises normalizing the value indicative of fluid responsiveness based on the value indicative of changes in vascular tone of the subject.

18. The method of claim 11, further comprising:

determining, using the pulse oximetry monitor, whether or not to administer fluid to the subject based on the fluid responsiveness index; and

administering, using a fluid delivery device coupled to the pulse oximetry monitor, fluid to the subject when the pulse oximetry monitor determines to administer fluid.

19. A tangible and non-transitory computer readable medium that includes one or more sets of instructions configured to direct a computer to:

receive a photoplethysmograph (PPG) signal from a pulse oximetry sensor secured to a subject;

determine a fluid responsiveness value based on the PPG signal;

determine a value indicative of changes in vascular tone of the subject based on the PPG signal; and

determine a fluid responsiveness index of the subject based on the fluid responsiveness value and the value indicative of changes in vascular tone of the subject.

20. The tangible and non-transitory computer readable medium of claim 19, further configured to direct the computer to determine whether or not to administer fluids based on the fluid responsiveness index.

21. The tangible and non-transitory computer readable medium of claim 19, wherein the value indicative of changes in vascular tone of the subject comprises at least one of a relative amplitude ratio of the PPG signal, a width of at least one primary peak of the PPG signal, a time difference between at least one primary peak of the physiological signal and a trailing peak of the PPG signal, and a pleth modulation ratio of the PPG signal.