DETERMINING A CHARACTERISTIC BLOOD PRESSURE

• US 20100331724A1
• Filed: 06/30/2009
• Published: 12/30/2010
• Est. Priority Date: 06/30/2009
• Status: Active Grant

• Current Assignee: Nellcor Puritan Bennett Ireland
• Original Assignee: Nellcor Puritan Bennett Ireland
• Inventors: Sethl, Rakesh, Addison, Paul Stanley, Watson, James N.
• Granted Patent: US 9,198,582 B2
• Time in Patent Office: Days
• US Class Current: 600/561
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/16 Devices for psychotechnics using teaching or educational appliances G09B1/00 - G09B7/00; Testing reaction times ; Devices for evaluating the psychological state
• CPC Class Codes: A61B 5/165 Evaluating the state of mind, e.g. depression, anxiety
• CPC Class Codes: A61B 5/6816 Ear lobe
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6829 Foot or ankle
• CPC Class Codes: A61B 5/6838 Clamps or clips
• CPC Class Codes: A61B 5/726 using Wavelet transforms

Abstract

The present disclosure relates to monitoring a characteristic physiological parameter of a patient during a suitable time period that either precedes or follows a triggering event, such as a clinician/patient interaction, that may negatively impact the physiological parameter. In some embodiments, physiological parameter values falling between one or more pre-set thresholds may be used to derive the characteristic physiological parameter. In some embodiments, tracking the physiological parameter may provide additional information about the patient'"'"'s status. In some embodiments, confidence measures may be associated with, or may be used to analyze features of the patient signal to derive information about, the characteristic physiological parameter. The patient signal used to derive a patient'"'"'s physiological parameter may be of an oscillatory nature or may include oscillatory features that may be analyzed to derive a characteristic respiration rate.

Claims

1. A method for determining a characteristic physiological parameter of a patient, the method comprising:

determining a physiological parameter of the patient based at least in part on a signal obtained from a patient sensor;

detecting a first physiological parameter event, wherein the first physiological parameter event is detected based at least in part on a first altered portion of the physiological parameter; and

determining the characteristic physiological parameter of the patient based at least in part on a selected portion of the physiological parameter other than the first altered portion of the physiological parameter, wherein the characteristic physiological parameter is determined to assess a clinical status of the patient.

2. The method of claim 1, wherein the physiological parameter is blood pressure, wherein the first physiological parameter event is a blood pressure event, and wherein the method further comprises:

determining a first blood pressure value based at least in part on the first blood pressure event;

identifying a relaxation time based at least in part on the blood pressure, wherein the relaxation time occurs after the first blood pressure event; and

determining the characteristic blood pressure based at least in part on the blood pressure at the relaxation time.

3. The method of claim 2 wherein the characteristic blood pressure is continuously determined.

4. The method of claim 2 wherein the relaxation time is identified based at least in part on the slope of the blood pressure reaching a threshold value.

5. The method of claim 2, further comprising generating at least one confidence measure associated with the characteristic blood pressure.

6. The method of claim 2, wherein the difference between the first blood pressure value and the characteristic blood pressure are analyzed at least in part to indicate the stress of the patient.

7. The method of claim 6, wherein the difference between the first blood pressure value and the characteristic blood pressure is normalized by one of the group consisting of the first blood pressure value, the characteristic blood pressure, and a weighted mean of the first blood pressure value and the characteristic blood pressure.

8. The method of claim 2, wherein the relaxation time is analyzed at least in part to indicate the ability of the patient to respond to stressful situations.

9. The method of claim 7, wherein the relaxation time is normalized by the mean value of a relaxation time of a representative patient population.

10. A system for determining a characteristic physiological parameter of a patient, the system comprising:

an input signal generator for generating a signal;

a processor coupled to the input signal generator, wherein the processor is configured to;

determine a physiological parameter of the patient based at least in part on the signal;

detect a first physiological parameter event, wherein the first physiological parameter event is detected based at least in part on a first altered portion of the physiological parameter; and

determine the characteristic physiological parameter of the patient based at least in part on a selected portion of the physiological parameter other than the first altered portion of the physiological parameter,

wherein the characteristic physiological parameter is determined to assess a clinical status of the patient; and

an output coupled to the processor, wherein the output is configured to display the characteristic physiological parameter.

11. The system of claim 10, wherein the physiological parameter is blood pressure, wherein the first physiological parameter event is a blood pressure event, and wherein the processor is further configured to:

determine a first blood pressure value based at least in part on the first blood pressure event;

identify a relaxation time based at least in part on the blood pressure, wherein the relaxation time occurs after the first blood pressure event; and

determine the characteristic blood pressure based at least in part on the blood pressure at the relaxation time.

12. The system of claim 11 wherein the characteristic blood pressure is continuously determined.

13. The system of claim 11 wherein the processor is further configured to identify the relaxation time based at least in part on the slope of the blood pressure reaching a threshold value.

14. The system of claim 11, wherein the processor is further configured to generate at least one confidence measure associated with the characteristic blood pressure.

15. The system of claim 11 wherein the processor is further configured to analyze at least in part the difference between the first blood pressure value and the characteristic blood pressure to indicate the stress of the patient.

16. The system of claim 15 wherein the processor is further configured to normalize the difference between the first blood pressure value and the characteristic blood pressure by one of the group consisting of the first blood pressure value, the characteristic blood pressure, and a weighted mean of the first blood pressure value and the characteristic blood pressure

17. The system of claim 11, wherein the processor is further configured to analyze at least in part the relaxation time to indicate the ability of the patient to respond to stressful situations.

18. The system of claim 16, wherein the processor is further configured to normalize the relaxation time by the mean value of a relaxation time of a representative patient population.

19. A computer-readable medium for use in determining a characteristic physiological parameter of a patient, the computer-readable medium having computer program instructions recorded thereon for:

determining a physiological parameter of the patient based at least in part on a signal obtained from a patient sensor;

detecting a first physiological parameter event, wherein the first physiological parameter event is detected based at least in part on a first altered portion of the physiological parameter; and

determining the characteristic physiological parameter of the patient based at least in part on a selected portion of the physiological parameter other than the first altered portion of the physiological parameter, wherein the characteristic physiological parameter is determined to assess a clinical status of the patient.

20. The computer-readable medium of claim 19, wherein the physiological parameter is blood pressure, wherein the first physiological parameter event is a blood pressure event, and wherein the method further comprises:

determining a first blood pressure value based at least in part on the first blood pressure event;

identifying a relaxation time based at least in part on the blood pressure, wherein the relaxation time occurs after the first blood pressure event; and

determining the characteristic blood pressure based at least in part on the blood pressure at the relaxation time.