Method and system for detecting vascular conditions using an occlusive arm cuff plethysmograph

• US 20020111554A1
• Filed: 10/29/2001
• Published: 08/15/2002
• Est. Priority Date: 06/12/2000
• Status: Active Grant

• Current Assignee: Gary M. Drzewiecki, Robert B. Drzewiecki
• Original Assignee: Gary M. Drzewiecki, Robert B. Drzewiecki
• Inventors: Drzewiecki, Gary M., Drzewiecki, Robert B.
• Granted Patent: US 6,626,840 B2
• Time in Patent Office: Days
• US Class Current: 600/490
• CPC Class Codes: A61B 5/02007 Evaluating blood vessel condition, e.g. elasticity, compliance
• CPC Class Codes: A61B 5/02255 the pressure being controlled by plethysmographic signals, e.g. derived from optical sensors
• CPC Class Codes: A61B 5/1073 Measuring volume, e.g. of limbs

Abstract

A method and system are provided for detecting various vascular conditions using an occlusive arm cuff plethysmograph. The system includes data acquisition hardware, including the occlusive arm cuff plethysmograph, for obtaining arterial and endothelial function data from a patient, processing means utilizing application or analysis software for analyzing the arterial and endothelial function data, and a database of computer models, such as brachial artery pressure versus lumen area curves (P-A curves) and brachial artery pressure versus compliance curves (P-C curves), developed by analyzing data for a plurality of subjects where their vascular conditions were known. The processing means diagnoses and predicts various vascular conditions pertaining to the patient by comparing or correlating the analyzed arterial and endothelial function data with the computer models stored within the database and presents the findings on a display.

Claims

1. A system for determining at least one vascular condition, comprising:

an occlusive arm cuff plethysmograph having an occlusive arm cuff for placement over a patient'"'"'s brachial artery, means for obtaining patient vascular data and means for outputting said patient vascular data;

at least one database storing predetermined vascular data and a plurality of corresponding vascular conditions;

at least one processor; and

a plurality of programmable instructions, executed by the at least one processor, for correlating said patient vascular data with said predetermined vascular data stored within said at least one database and determining at least a portion of said predetermined vascular data which exhibits the maximum correlation with said patient vascular data, wherein said at least one vascular condition is determined to be at least one of said plurality of corresponding vascular conditions which corresponds to a portion of said predetermined vascular data.

2. The system according to claim 1, wherein said means for obtaining patient vascular data comprises:

a flow restrictor for receiving a pressure input from said occlusive arm cuff and outputting a pressure output according to a flow resistance parameter, R, characteristic of aid flow restrictor;

a pressure transducer for receiving said pressure output and transmitting at least one pressure reading output; and

a processor for receiving said at least one pressure reading output from said pressure transducer and determining vascular measurements based on said at least one pressure reading output.

3. The method according to claim 1, further comprising:

a hand pump connected to said occlusive arm cuff; and

a pressure gage connected to said occlusive arm cuff via a T-connector.

4. The method according to claim 3, wherein said occlusive arm cuff, said hand pump and said pressure gage comprise a blood pressure monitor.

5. The system according to claim 1, wherein said predetermined vascular data includes a plurality of computer models, including arterial pressure versus lumen area curves (P-A curves) and arterial pressure versus compliance curves (P-C curves).

6. The system according to claim 1, wherein said means for outputting said vascular data outputs said patient vascular data as at least one waveform.

7. The system according to claim 1, further comprising at least one display for displaying data.

8. The system according to claim 1, wherein said at least one database is located at a remote location and said at least one processor accesses said at least one database via a network data connection.

9. The system according to claim 1, wherein said at least one processor is connected to said occlusive arm cuff plethysmograph via an analog-to-digital converter.

10. The system according to claim 1, wherein said plurality of programmable instructions are stored within a memory of said at least one processor.

11. The system according to claim 1, wherein said at least one processor and said at least one database are remotely located from said occlusive arm cuff plethysmograph.

13. The occlusive arm cuff plethysmograph according to claim 12, wherein said processor determines said cuff compliance, C_cuff, by the following equation:

C_cuff=[P_cuff[i−

1]*Δ

t]/R₂[P_cuff[i]−

P_cuff[i−

1]],

where P_cuff is the pressure within the cuff as measured by said pressure transducer, i indicates the iteration index and Δ

t is the data sample period.

14. The occlusive arm cuff plethysmograph according to claim 12, wherein said processor determines said cuff compliance, C_cuff, by the following equation:

C_cuff={square root}P_cuff[i−

1]*Δ

t/{square root}R₁[P_cuff[i]−

P_cuff[i−

1]],

where P_cuff is the pressure within the cuff as measured by said pressure transducer, i indicates the iteration index and Δ

t is the data sample period.

15. The occlusive arm cuff plethysmograph according to claim 12, wherein said flow restrictor exhibits laminar flow resistance.

17. The method according to claim 16, wherein said predetermined vascular data includes a plurality of computer models, including arterial pressure versus lumen area curves (P-A curves) and arterial pressure versus compliance curves (P-C curves).

18. The method according to claim 16, further comprising the step of displaying said at least one determined vascular condition.

19. The method according to claim 16, further comprising the step of accessing said at least one database via a network connection.

20. The method according to claim 16, further comprising the step of predicting at least one vascular condition by correlating said patient vascular data with said predetermined vascular data.

21. The method according to claim 16, further comprising the step of storing said patient vascular data within said at least one database.

22. The method according to claim 16, further comprising the steps of:

deflating said occlusive arm cuff;

placing an additional occlusive arm cuff over the patient'"'"'s brachial artery;

inflating said additional occlusive arm cuff over the patient'"'"'s systolic pressure and maintaining said additional occlusive arm cuff over the patient'"'"'s systolic pressure for a predetermined time period;

inflating said occlusive arm cuff and deflating said additional occlusive arm cuff to obtain vasolidated vascular patient data; and

determining endothelial function of the smooth muscle wall of the patient'"'"'s brachial artery using said vasolidated vascular patient data.

23. The method according to claim 22, wherein said step of inflating said additional occlusive arm cuff entails inflating said occlusive arm cuff to 50 mm Hg over the patient'"'"'s systolic pressure.

24. The method according to claim 22, wherein said predetermined time period is approximately five minutes.

25. The method according to claim 22, further comprising the step of storing said vasolidated vascular patient data within said at least one database.

12. An occlusive arm cuff plethysmograph for measuring patient vascular data comprising:

an arm cuff configured for placement over a patient'"'"'s brachial artery;

a pump for inflating said arm cuff,

a flow restrictor for controlling airflow out of said arm cuff depending on a valve flow resistance parameter, R, characteristic of said flow restrictor;

a pressure transducer for measuring the pressure in said arm cuff and outputting at least one pressure reading; and

a processor for receiving said at least one pressure reading and determining compliance of said arm cuff.

16. A method for determining at least one vascular condition, comprising the steps of:

providing an occlusive arm cuff plethysmograph having an occlusive arm cuff for placement over a patient'"'"'s brachial artery, means for obtaining patient vascular data and means for outputting said patient vascular data;

placing said occlusive arm cuff plethysmograph over said patient'"'"'s brachial artery;

inflating said occlusive arm cuff, obtaining said patient vascular data by said means for obtaining patient vascular data, and outputting said patient vascular data by said means for outputting;

providing at least one database storing predetermined vascular data and a plurality of corresponding vascular conditions; and

executing by at least one processor a plurality of programmable instructions for correlating said patient vascular data with said predetermined vascular data stored within said at least one database and determining at least a portion of said predetermined vascular data which exhibits the maximum correlation with said patient vascular data, wherein said at least one vascular condition is determined to be at least one of said plurality of corresponding vascular conditions which corresponds to a portion of said predetermined vascular data.