Methods and systems for recalibrating a blood pressure monitor with memory

• US 8,825,428 B2
• Filed: 11/30/2010
• Issued: 09/02/2014
• Est. Priority Date: 11/30/2010
• Status: Active Grant

• Current Assignee: Nellcor Puritan Bennett Ireland
• Original Assignee: Neilcor Puritan Bennett Ireland
• Inventors: Addison, Paul Stanley, Watson, James N.
• Primary Examiner(s): BHAT, ADITYA S
• Application Number:
  US12/956,963
• Publication Number:
  US 20120136605A1
• Time in Patent Office: 1,372 Days
• Field of Search: None
• US Class Current: 702/98
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 2560/0271 using a remote monitoring unit
• CPC Class Codes: A61B 5/02125 of pulse wave propagation time
• CPC Class Codes: A61B 5/02141 Details of apparatus construction, e.g. pump units or housings therefor, cuff pressurising systems, arrangements of fluid conduits or circuits A61B5/02233, A61B5/0235 take precedence
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence
• CPC Class Codes: A61B 5/7235 Details of waveform analysis A61B5/349 takes precedence
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: G16H 40/40 for the management of medical equipment or devices, e.g. scheduling maintenance or upgrades
• CPC Class Codes: G16Z 99/00 Subject matter not provided for in other main groups of this subclass

Abstract

Systems and methods are provided for storing and recalling metrics associated with physiological signals. It may be determined that the value of a monitored physiological metric corresponds to a stored value. In such cases, a patient monitor may determine that a calibration is not desired. In some cases, a patient monitor may recall calibration parameters associated with the stored value if it determined that the stored value corresponds to the monitored metric value.

Claims

1. A method for calibrating a blood pressure monitor, the method comprising:

receiving a photoplethysmograph (PPG) signal;

monitoring a value of at least one metric derived at least in part from the PPG signal;

comparing the value of the metric to a stored value;

determining based at least in part on the comparison whether the value of the metric corresponds to the stored value; and

determining, using a processor, whether to update current calibration parameters of the blood pressure monitor based at least in part on the comparison, wherein the calibration parameters are used for calculating blood pressure values.

2. The method of claim 1, wherein the determining whether to update current calibration parameters further comprises determining whether to update the current calibration parameters based further at least in part on whether current calibration parameters correspond to stored calibration parameters associated with the stored value, the method further comprising:

updating the current calibration parameters with the stored calibration parameters if it is determined that the current calibration parameters do not correspond to the stored calibration parameters; and

retaining the current calibration parameters if it is determined that the current calibration parameters correspond to the stored calibration parameters.

3. The method of claim 2, wherein updating the calibration parameter further comprises recalling previous calibration parameters.

4. The method of claim 1, wherein the stored value is catalogued in the database.

5. The method of claim 1, wherein the stored value is stored at time when a calibration of the blood pressure monitor is performed.

6. The method of claim 1, wherein the at least one feature is based at least in part on PPG signal morphology.

7. The method of claim 1, wherein the PPG signal morphology comprises a derivative, integral, moment, domain, range, peak value and/or coefficients of a signal transform, and/or a combination thereof.

8. The method of claim 1, wherein comparing the value of the metric and the stored value further comprises using a pattern matching technique.

9. The method of claim 1, wherein comparing the value of the metric and the stored value further comprises comparing a threshold to a difference between the value of the at least one monitored metric and the stored value.

10. The method of claim 1, further comprising receiving an auxiliary PPG signal, wherein the metric corresponds to a time difference between at least one portion of the PPG signal and at least one portion of the auxiliary PPG signal.

11. A system for determining physiological information about a subject, the system comprising:

a signal input configured to receive at least one PPG signal of a subject from at least one sensing device;

at least one processing device coupled to the signal input, wherein the at least one processing device is configured to;

monitor a value of at least one metric derived at least in part from the at least one PPG signal;

compare the value of the at least one metric to a stored value;

determine based at least in part on the comparison whether the value of the metric corresponds to the stored value; and

determine whether to update calibration parameters of the blood pressure monitor based at least in part on the comparison, wherein the calibration parameters are used for calculating blood pressure values.

12. The system of claim 11, wherein the at least one processing device comprises a memory device.

13. The system of claim 11, wherein the at least one processing device is coupled to at least one memory device.

14. The system of claim 11, wherein the at least one PPG signal comprises two PPG signals measured at two different sites of the subject.

15. The system of claim 11, wherein the at least one metric comprises a differential pulse transit time, blood pressure, heart rate, PPG signal derivative, PPG signal integral, PPG signal moment, PPG signal domain, PPG signal range, PPG signal peak value and/or coefficients of a PPG signal transform, and/or a combination thereof.

16. The system of claim 11, wherein comparing the value of the metric to the value stored in the memory device further comprises the at least one processing device being further configured to use a pattern matching technique.

17. The system of claim 11, wherein the value stored in the memory device is catalogued in a database stored in the memory device.

18. The system of claim 11, wherein the at least one processing device is further configured to perform a calibration of the system.

19. The system of claim 11, wherein the at least one processing device is further configured to search for the stored value stored in a memory device based at least in part on the value of the monitored metric.

20. The system of claim 11, wherein the at least one processing device is further configured to recall the stored value from a memory device.