Sphygmogram measure method and device for two closed measured points

• US 20030204143A1
• Filed: 04/24/2003
• Published: 10/30/2003
• Est. Priority Date: 04/26/2002
• Status: Active Grant

• Current Assignee: E-Med Biotech, Inc.
• Original Assignee: E-Med Biotech, Inc.
• Inventors: Lin, Chin-Yuh
• Granted Patent: US 6,911,009 B2
• Time in Patent Office: Days
• US Class Current: 600/485
• CPC Class Codes: A61B 5/01 Measuring temperature of body parts ; Diagnostic temperature sensing, e.g. for malignant or inflamed tissue clinical contact thermometers G01K13/20
• CPC Class Codes: A61B 5/02035 Determining blood viscosity
• CPC Class Codes: A61B 5/02125 of pulse wave propagation time
• CPC Class Codes: A61B 5/0285 Measuring or recording phase velocity of blood waves
• CPC Class Codes: A61B 5/489 Blood vessels

Abstract

A sphygmogram measure method and device includes an upstream and a downstream pressure sensor arranged in accordance with the bloodstream direction to measure the pulse pressure of two adjacent points on radial artery in the wrist. The pulse pressures are processed and converted to analog signals by an amplitude filter circuit and an adjusting circuit. The analog signal of upstream pulse pressure is converted to a digital signal, which is stored in a digital signal process unit. The signals of upstream pulse pressure and downstream pulse pressure are also transmitted as a start signal and a stop signal respectively to a counter which measures the time lag of a pulse wave passing through the two pressure sensors. The digital signal process unit uses the digital signals of upstream pulse pressure and time lag to calculate the digital signal of downstream pulse pressure.

Claims

1. A sphygmogram measure method for measuring pulse pressure at two adjacent measure points, comprising the steps of:

Step 1;

positioning an upstream pressure sensor and a downstream pressure sensor at a certain distance L in accordance with the bloodstream direction;

Step 2;

acquiring the signals from the upstream and the downstream pressure sensors and through the preamplifier, filter, and offset adjust circuits to acquire the analogy form of upstream pressure P₀(t) and downstream pressure P_L(t);

Step 3;

converting the analogy form of upstream pressure P₀(t) into a digital upstream pressure P₀(n) by an A/D converter that the sampling frequency is 200 to 400 Hz and then storing the digital upstream pressure into the digital signal process unit;

Step 4;

filtering out upstream pressure P₀(t) and downstream pressure P_L(t) by two low-pass filters to have their fundamental waves;

Step 5;

detecting the zero-cross signal of the fundamental wave of the upstream and downstream pressure signals to trigger and stop the counting of the counter, and obtain the time lag τ

between these two pressures by output of the counter;

Step 6;

storing the digitized upstream pressure signal P₀(n) and time lag τ

in the digital signal process unit; and

Step 7;

calculating the digital downstream pressure P_L(n) in the digital signal process unit by using the upstream pressure P₀(n) and time lag τ

, where P_L(n)≈

P₀(n+τ

).

2. The sphygmogram measure method as claimed in claim 1, wherein the distance between upstream pressure sensor and downstream pressure sensor is 2 to 3 millimeters.

3. A sphygmogram measure device for measuring pulse pressure at two adjacent measure points, comprising:

a wrist holder that stabilizes a wrist but not presses the vessel therein;

a set of pressure sensing device mounted in the wrist holder and comprising a seat, an upstream pressure sensor mounted in the seat, a downstream pressure sensor mounted in the seat and a drive device disposing the seat downwards; and

a detecting circuit connected to the upstream pressure sensor and the downstream pressure sensor.

4. The sphygmogram measure device of claim 3, wherein the upstream pressure sensor comprises a first casing mounted in the seat, an upstream chip mounted in the first casing and a first resilient cover covering the upstream chip, the downstream pressure sensor comprises a second casing mounted in the seat, a downstream chip mounted in the second casing and a second resilient cover covering the downstream chip, a first chamber defined between the upstream chip and the first resilient cover and a second chamber defined between the downstream chip and the second resilient cover, the first and the second chambers filled with fluid, the central tip of the first resilient cover being a first column head which extends out of the bottom edge of first casing and the central tip of second resilient cover being a second column head extending out of the bottom edge of second casing.

5. The sphygmogram measure device in claim 3, wherein the contact tips of first column head and second column head must be narrower than the diameter of the measured vessel, and the distance between first detector and second detector is about 2 to 3 millimeters.

6. The sphygmogram measure device in claim 3, wherein the detecting circuit comprises:

a preamplifier circuit and a filter circuit connected to the upstream pressure sensor and the downstream pressure sensor respectively;

two offset adjusting circuits connected to the two amplify filter circuits respectively;

two low-pass filter circuits connected to the two adjusting circuits respectively;

a peak detector circuit connected to the two low-pass filter circuits, and a counter connected to the phase check circuit;

a high-frequency clock connected to the counter;

an analog-to-digital converter connected to the offset adjusting circuit and the low-pass filter circuit of the upstream pressure sensor; and

an input/output interfacing the digital signal process unit and analogy-to-digital converter or a digital input device.

7. The sphygmogram measure device in claim 3, wherein the detecting circuit processes data with the steps of:

Step 1;

positioning an upstream pressure sensor and a downstream pressure sensor at a certain distance L in accordance with the bloodstream direction;

Step 2;

acquiring the signals from upstream and downstream pressure sensors and through the preamplifier, filter, and offset adjust circuits to have the analogy form of upstream pressure P₀(t) and downstream pressure P_L(t);

Step 3;

converting the analogy form of upstream pressure P₀(t) into a digital upstream pressure P₀(n) by an A/D converter that the sampling frequency is 200 to 400 Hz and then storing the digital upstream pressure into the digital signal process unit;

Step 4;

filtering out the upstream pressure P₀(t) and the downstream pressure P_L(t) by two low-pass filters to have their fundamental waves;

Step 5;

detecting the zero-cross signal of the fundamental wave of the upstream and downstream pressure signals to trigger and stop the counting of the counter, and obtaining the time lag τ

between these two pressures by an output of the counter;

Step 6;

storing the digitized upstream pressure signal P₀(n) and time lag τ

in the digital signal process unit; and

Step 7;

calculating the digital downstream pressure P_L(n) in the digital signal process unit by using upstream pressure P₀(n) and time lag τ

, where P_L(n)≈

P₀(n+τ

).