Digital Control Method for Measuring Blood Pressure

• US 20110105917A1
• Filed: 10/29/2010
• Published: 05/05/2011
• Est. Priority Date: 10/29/2009
• Status: Active Grant

• Current Assignee: CNSystems Medizintechnik AG
• Original Assignee: CNSystems Medizintechnik AG
• Inventors: FORTIN, JÜRGEN, GRÜLLENBERGER, RUPERT
• Granted Patent: US 8,343,062 B2
• Time in Patent Office: Days
• US Class Current: 600/490
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
• CPC Class Codes: A61B 5/02241 of small dimensions, e.g. adapted to fingers
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal

Abstract

A system and method of digital control for a blood pressure measurement system is provided. According to at least one embodiment, a photo-plethysmographic (PPG) system produces a frequency signal that corresponds to the measured light in the PPG system. Such light may be indicative of blood volume in a vein or artery. The frequency signal may be used to control one or more pressure valves of the system in order to measure blood pressure and hold the frequency signal constant.

Claims

1. A device for continuous blood pressure measurement comprising:

a pressure cuff adapted to be placed over an artery in a human finger, the cuff including a PPG system having at least one light source and at least one light detector;

a pressure system comprising;

at least one pump,

at least one valve or valve system, and

at least one pressure sensor; and

a controller for controlling pressure in the cuff by altering the valve or valve system, wherein the one or more light detectors are associated with at least one light-to-frequency conversion (LFC) device.

2. The blood pressure measurement device according to claim 1, wherein the controller is a computing device.

3. The blood pressure measurement device according to claim 2, wherein the LFC device is electrically connected to a digital input of the computing device.

4. The blood pressure measurement device according to claim 3, wherein the LFC device produces a frequency output based on light intensity measured from the one or more light detectors, and wherein the frequency output is held substantially constant by the altering the pressure in the cuff.

5. The blood pressure measurement device according to claim 2, wherein the at least one valve or valve system is controlled via a digital output from the computing device.

6. The blood pressure measurement device according to claim 5, wherein the digital output is a pulse width modulated (PWM) signal.

7. The blood pressure measurement device according to claim 2, wherein the at least one light source and the at least one light detector are controlled via a digital output of the computing device.

8. The blood pressure measurement device according to claim 7, wherein a blanking-interval of the light source is used for ambient light detection.

9. The blood pressure measurement device according to claim 2, wherein the computing device receives information from a calibration device.

10. The blood pressure measurement device according to claim 1, wherein the blood pressure measurement device receives information from a hydrostatic correction system.

11. The blood pressure measurement device according to claim 1, wherein the blood pressure measurement device receives scaling information from at least one other device.

12. The blood pressure measurement device according to claim 11, wherein the blood pressure measurement device calculates a scaled blood pressure curve and transmits the scaled blood pressure curve to the other device.

13. A method for continuously measuring blood pressure comprising:

placing a photo-plethysmographic (PPG) system over an artery or vein in a human finger, the PPG system producing a PPG signal based on volume of the artery or vein, the PPG system including at least one light source and at least one light detector;

utilizing a computing device to alter a pressure inside the cuff by altering a valve or valve system that is connected to a pump and pressure sensor,

wherein, based on the measured blood volume of the artery or vein, a frequency signal is produced by a light-to-frequency conversion (LFC) device, and

wherein the computing device holds the frequency signal substantially constant by altering the cuff pressure.

14. The method of claim 13, wherein the computing device alters the valve or valve system based on the frequency signal.

15. The method of claim 13, wherein the LFC device produces a frequency output based on light intensity measured from the one or more light detectors.

16. The method of claim 13, further comprising, detecting the ambient light during a blanking-interval of the light source.

17. A sensor for continuously measuring blood pressure comprising:

a pressure cuff adapted to be placed over an artery in a human finger;

a PPG system inside the cuff having at least one light source and at least one light detector;

at least one computing device for receiving and submitting electrical digital signals and power supply signals;

one or more air connectors for applying pressure to the cuff,

wherein the at least one light detector is configured as a light-to-frequency conversion (LFC) device, and

wherein, based on measured light, the LFC device produces a frequency signal to the at least one computing device to the control unit of the sensor.

18. The sensor of claim 17, wherein the at least computing device comprises:

a processor; and

memory storage coupled to the processor having stored thereon instructions, which, when executed by the processor, cause the computing device to carry out functions, the functions comprising;

holding the frequency signal substantially constant by altering a pressure inside the cuff.

19. The sensor of claim 18, wherein altering the pressure inside the cuff comprises altering a valve or valve system that is connected to a pump and pressure sensor.

20. The sensor of claim 19, wherein altering a valve or valve system that is connected to a pump and pressure sensor comprises using a pulse-width-modulated (PWM) signal to control the valve or valve system, wherein opening and closing of the valve or valve system is a function of a duty cycle of the PWM signal.