Evaluation of peripheral arterial disease in a patient using an oscillometric pressure signal obtained at a lower extremity of the patient

• US 9,211,070 B2
• Filed: 09/22/2011
• Issued: 12/15/2015
• Est. Priority Date: 09/23/2010
• Status: Expired due to Fees

• Current Assignee: Cleveland Clinic Foundation, Summit Doppler Systems Incorporated
• Original Assignee: Cleveland Clinic Foundation
• Inventors: Gornik, Heather L., Jarrell, Kenneth E., Jones, David C., Wang, Xiaofeng
• Primary Examiner(s): Kahelin, Michael
• Assistant Examiner(s): TRAN, THO Q
• Application Number:
  US13/239,751
• Publication Number:
  US 20120078125A1
• Time in Patent Office: 1,545 Days
• Field of Search: 600/490, 600/491, 600/501, 600/500, 600/495, 600/494
• US Class Current: 1/1
• CPC Class Codes: A61B 5/02007 Evaluating blood vessel condition, e.g. elasticity, compliance
• CPC Class Codes: A61B 5/02225 using the oscillometric method
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: A61B 5/7264 Classification of physiological signals or data, e.g. using neural networks, statistical classifiers, expert systems or fuzzy systems neural networks per se G06N3/00; expert systems per se G06N5/00
• CPC Class Codes: G16H 50/20 for computer-aided diagnosis, e.g. based on medical expert systems

Abstract

Systems, methods, and products for determining indicated blood pressure values and/or characterizing a condition of a patient. The systems, methods, and products are capable of determining indicated blood pressure values in a lower extremity of a patient using an oscillometric technique. An oscillometric signal obtained from the lower extremity of the patient is analyzed, and the patient may be classified into one of a plurality of diagnostic classes. Each diagnostic class may have an associated ratio value. Based on the diagnostic class into which the patient is classified, a selected lower extremity characteristic ratio may be selected. A lower extremity indicated blood pressure value may be obtained by oscillometric processing using the selected ratio. This lower extremity indicated blood pressure value may be used with an upper extremity indicated blood pressure value to perform an extremity blood pressure ratio (EBPR) examination.

Claims

1. A system operable to determine presence of peripheral artery disease using an oscillometric blood pressure value obtained at a lower extremity of a patient, said system comprising:

a first pressure applicator positionable at a location on the lower extremity of a patient, said first pressure applicator being controllable to apply a pressure to occlude blood flow in a portion of the lower extremity and to reduce the pressure applied thereby to permit blood flow to return in the portion of the lower extremity;

a first pressure transducer in operative communication with said first pressure applicator to obtain a first oscillometric pressure signal from the lower extremity as pressure applied by the first pressure applicator to the lower extremity is reduced;

a second pressure applicator positionable at a location on an upper extremity of a patient, said second pressure applicator being controllable to apply a pressure to occlude blood flow in a portion of the upper extremity and to reduce the pressure applied thereby to permit blood flow to return in the portion of the upper extremity;

a second pressure transducer in operative communication with said second pressure applicator to obtain a second oscillometric pressure signal from the upper extremity as pressure applied by the second pressure applicator to the upper extremity is reduced;

a processor in operative communication with said first pressure transducer and with said second pressure transducer;

a selection module executable by said processor, said selection module operating when executed by said processor to compare the first oscillometric pressure signal obtained by the first pressure transducer to the second oscillometric pressure signal obtained by the second pressure transducer to characterize the patient into one of a first diagnostic class and a second diagnostic class, said selection module also operating when executed by said processor to select a lower extremity characteristic ratio from a plurality of ratio values such that a first ratio value is selected from the plurality of ratio values if the patient is characterized by the selection module as being in the first diagnostic class and a second ratio value is selected from the plurality of ratio values if the patient is characterized by the selection module as being in the second diagnostic class; and

a blood pressure determination module executable by said processor, the blood pressure determination module operating when executed by said processor (a) to detect a maximum amplitude of the first oscillometric pressure signal obtained by the first pressure transducer and (b) to multiply the detected maximum amplitude of the first oscillometric pressure signal by the selected lower extremity characteristic ratio to provide an adjusted amplitude associated with the first oscillometric pressure signal to obtain an indicated blood pressure value in the lower extremity, the blood pressure determination module also operating when executed by said processor (x) to detect a maximum amplitude of the second oscillometric pressure signal obtained by the second pressure transducer and (y) to multiply the detected maximum amplitude of the second oscillometric pressure signal by a selected upper extremity characteristic ratio to provide an adjusted amplitude associated with the second oscillometric pressure signal to obtain an indicated blood pressure value in the upper extremity,

the processor being operable to calculate a ratio between the indicated blood pressure value in the lower extremity obtained by operation of the blood pressure determination module executed by said processor and the indicated blood pressure value in the upper extremity obtained by operation of the blood pressure determination module executed by said processor to produce a blood pressure ratio for evaluating the presence of peripheral artery disease in the patient.

2. The system of claim 1, wherein at least one of the blood pressure determination module and the selection module comprises machine readable code stored on a memory in operative communication with said processor, and wherein said processor is operable to execute said machine readable code to execute said at least one of the blood pressure determination module and the selection module.

3. The system of claim 1, further comprising:

a transform module executable by said processor to transform the first oscillometric pressure signal into a frequency domain representation of the first oscillometric pressure signal, and wherein the blood pressure determination module operates when executed by said processor to utilize the frequency domain representation of the first oscillometric pressure signal in determining the maximum amplitude at the fundamental frequency of the first oscillometric pressure signal.

4. The system of claim 1, wherein the upper extremity characteristic ratio is different than the selected lower extremity characteristic ratio.

5. The system of claim 1, wherein the indicated blood pressure values in the upper and lower extremities comprise systolic pressure values.

6. The system of claim 1, wherein the location on the lower extremity comprises an ankle of the patient, and the location on the upper extremity comprises an arm of the patient.

7. The system of claim 6, wherein the blood pressure ratio comprises an ankle-brachial pressure index (ABI).

8. The system of claim 1, wherein said blood pressure determination module operates when executed by said processor to determine said maximum amplitude of the first oscillometric pressure signal within a window of interest of the first oscillometric pressure signal.

9. The system of claim 1, wherein the processor is in operative communication with the first pressure applicator and with the second pressure applicator.

10. A system operable to determine presence of peripheral artery disease using an oscillometric blood pressure value obtained at a lower extremity of a patient, said system comprising:

a first pressure applicator positionable at a location on the lower extremity of a patient, said first pressure applicator being controllable to apply a pressure to occlude blood flow in a portion of the lower extremity and to reduce the pressure applied thereby to permit blood flow to return in the portion of the lower extremity;

a first pressure transducer in operative communication with said first pressure applicator to obtain a first oscillometric pressure signal from the lower extremity as pressure applied by the first pressure applicator to the lower extremity is reduced;

a second pressure applicator positionable at a location on an upper extremity of a patient, said second pressure applicator being controllable to apply a pressure to occlude blood flow in a portion of the upper extremity and to reduce the pressure applied thereby to permit blood flow to return in the portion of the upper extremity;

a second pressure transducer in operative communication with said second pressure applicator to obtain a second oscillometric pressure signal from the upper extremity as pressure applied by the second pressure applicator to the upper extremity is reduced;

a processor in operative communication with said first pressure transducer and with said second pressure transducer;

a selection module executable by said processor, said selection module operating when executed by said processor to compare the first oscillometric pressure signal obtained by the first pressure transducer to a threshold value to characterize the patient into one of a first diagnostic class and a second diagnostic class, said selection module also operating when executed by said processor to select a lower extremity characteristic ratio from a plurality of ratio values such that a first ratio value is selected from the plurality of ratio values if the patient is characterized by the selection module as being in the first diagnostic class and a second ratio value is selected from the plurality of ratio values if the patient is characterized by the selection module as being in the second diagnostic class; and

a blood pressure determination module executable by said processor, the blood pressure determination module operating when executed by said processor (a) to detect a maximum amplitude of the first oscillometric pressure signal obtained by the first pressure transducer and (b) to multiply the detected maximum amplitude of the first oscillometric pressure signal by the selected lower extremity characteristic ratio to provide an adjusted amplitude associated with the first oscillometric pressure signal to obtain an indicated blood pressure value in the lower extremity, the blood pressure determination module also operating when executed by said processor (x) to detect a maximum amplitude of the second oscillometric pressure signal obtained by the second pressure transducer and (y) to multiply the detected maximum amplitude of the second oscillometric pressure signal by a selected upper extremity characteristic ratio to provide an adjusted amplitude associated with the second oscillometric pressure signal to obtain an indicated blood pressure value in the upper extremity,

the processor being operable to calculate a ratio between the indicated blood pressure value in the lower extremity obtained by operation of the blood pressure determination module executed by said processor and the indicated blood pressure value in the upper extremity obtained by operation of the blood pressure determination module executed by said processor to produce a blood pressure ratio for evaluating the presence of peripheral artery disease in the patient.

11. The system of claim 10, wherein at least one of the blood pressure determination module and the selection module comprises machine readable code stored on a memory in operative communication with said processor, and wherein said processor is operable to execute said machine readable code to execute said at least one of the blood pressure determination module and the selection module.

12. The system of claim 10, further comprising:

a transform module executable by said processor to transform the first oscillometric pressure signal into a frequency domain representation of the first oscillometric pressure signal, and wherein the blood pressure determination module operates when executed by said processor to utilize the frequency domain representation of the first oscillometric pressure signal in determining the maximum amplitude at the fundamental frequency of the first oscillometric pressure signal.

13. The system of claim 10, wherein the upper extremity characteristic ratio is different than the selected lower extremity characteristic ratio.

14. The system of claim 10, wherein the indicated blood pressure values in the upper and lower extremities comprise systolic pressure values.

15. The system of claim 10, wherein the location on the lower extremity comprises an ankle of the patient, and the location on the upper extremity comprises an arm of the patient.

16. The system of claim 15, wherein the blood pressure ratio comprises an ankle-brachial pressure index (ABI).

17. The system of claim 10, wherein said blood pressure determination module operates when executed by said processor to determine said maximum amplitude of the first oscillometric pressure signal within a window of interest of the first oscillometric pressure signal.

18. The system of claim 10, wherein the processor is in operative communication with the first pressure applicator and with the second pressure applicator.