Bilateral device, system and method for monitoring vital signs

• US 7,803,120 B2
• Filed: 05/27/2006
• Issued: 09/28/2010
• Est. Priority Date: 05/25/2006
• Status: Active Grant

• Current Assignee: Sotera Wireless Incorporated
• Original Assignee: Sotera Wireless Incorporated
• Inventors: Banet, Matthew John, Thompson, Michael James, Zhou, Zhou, Visser, Henk II
• Primary Examiner(s): Mallari; Patricia C
• Application Number:
  US11/420,744
• Publication Number:
  US 20070276262A1
• Time in Patent Office: 1,585 Days
• Field of Search: 600/485, 600/500, 600/508
• US Class Current: 600/485
• CPC Class Codes: A61B 5/02255 the pressure being controlled by plethysmographic signals, e.g. derived from optical sensors
• CPC Class Codes: A61B 5/02427 Details of sensor
• CPC Class Codes: A61B 5/0285 Measuring or recording phase velocity of blood waves
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6838 Clamps or clips
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives

Abstract

The invention features a monitoring device that measures a patient'"'"'s vital signs (e.g.). The device features a first sensor configured to attach to a first portion of the patient'"'"'s body that includes: i)a first electrode configured to generate a first electrical signal fron the first portion of the patient'"'"'s body; ii)a first light-emitting component; and iii)a first photodetector configured to receive radiation from the first portion of the patient'"'"'s body after the radiation is emitted by the first light-emiting component and in response generate a first optical waveform. The device also features a second sensor that includes essentially the same components. An amplifier system, in electrical contact with the first and second electrodes, receives first and second electrical signal from the two sensors to generate an electrical waveform. A processor, in electrical contact with the amplifier system, receives the electrical waveform, the first optical waveform, and the second optical waveform. The processor runs computer code that processes the input waveforms with an algorithm to determine at least one of the patient'"'"'s vital signs.

Claims

1. A method for measuring a blood pressure of a user, the method comprising:

generating a first optical waveform from a signal from a first optical sensor positioned on the user;

generating a second optical waveform from a signal from a second optical sensor positioned on the user, the second optical waveform generated simultaneously with the first optical waveform, the second optical sensor positioned a distinguishable distance from the first optical sensor on the user;

generating an electrical waveform from a signal from a first electrode positioned in proximity with the first optical sensor and a signal from a second electrode positioned in proximity with the second optical sensor;

using a microprocessor to determine a first pulse transit time, the first pulse transit time calculated by processing the electrical waveform and the first optical waveform;

using the microprocessor to determine a second pulse transit time, the second pulse transit time calculated by processing the electrical waveform and the second optical waveform;

processing the first optical signal or a processed version thereof and the second optical signal or a processed version thereof to determine a third pulse transit time; and

processing the first, second, and third pulse transit times to determine a blood pressure value for the user.

2. The method of claim 1, wherein determining the first pulse transit time further comprises determining a first point on the first optical waveform or a processed version thereof, determining a second point on the electrical waveform or a processed version thereof, and determining a time difference between the first and second points.

3. The method of claim 2, further comprising determining a mathematical derivative of the first optical waveform, and then determining the first point from a maximum value of the mathematical derivative of the first optical waveform.

4. The method of claim 1, wherein determining the second pulse transit time further comprises determining a first point on the second optical waveform or a processed version thereof, determining a second point on the electrical waveform or a processed version thereof, and then determining a time difference between the first and second points.

5. The method of claim 4, further comprising determining a mathematical derivative of the second optical waveform, and then determining the first point from a maximum value of the mathematical derivative of the second optical waveform.

6. The method of claim 1, wherein the processing further comprises comparing at least one of the first pulse transit time and the second pulse transit time to a predetermined mathematical relationship between pulse transit time and blood pressure.

7. The method of claim 1, further comprising processing at least one of the first optical waveform and the second optical waveform to determine a property related to arterial compliance.

8. The method of claim 7, further comprising taking a second derivative of at least one of the first optical waveform and the second optical waveform, and then processing the second derivative to determine the property related to arterial compliance.

9. The method of claim 1, further comprising comparing the first optical waveform and the second optical waveform to determine a property related to blood flow along two different arterial pathways of the user.

10. A method for measuring a blood pressure of a user, the method comprising:

generating a first optical waveform from a signal from a first optical sensor positioned on a finger of a right-hand of the user;

generating a second optical waveform from a signal from a second optical sensor, the second optical waveform generated simultaneously with the first optical waveform, the second optical sensor positioned on a finger of a left-hand of the user;

generating an electrical waveform from a signal from a first electrode positioned in proximity with the first optical sensor and a signal from a second electrode positioned in proximity with the second optical sensor;

using a microprocessor to determine a first pulse transit time, the first pulse transit time calculated by processing the electrical waveform in and the first optical waveform;

using the microprocessor to determine a second pulse transit time, the second pulse transit time calculated by processing the electrical waveform and the second optical waveform; and

processing the first pulse transit time and the second pulse transit time to determine a blood pressure value for the user.

11. The method of claim 10, further comprising processing the first optical signal or a processed version thereof and the second optical signal or a processed version thereof to determine a third pulse transit time.

12. The method of claim 11, further comprising processing the third pulse transit time to determine a blood pressure value for the user.

13. A method for measuring a blood pressure of a user, the method comprising:

generating a first optical waveform in from a signal from a first optical sensor positioned on the user;

generating a second optical waveform from a signal from a second optical sensor positioned on the user, the second optical waveform generated simultaneously with the first optical waveform, the second optical sensor positioned a distinguishable distance from the first optical sensor on the user;

generating an electrical waveform from a signal from a first electrode positioned in proximity with the first optical sensor and a signal from a second electrode positioned in proximity with the second optical sensor;

using a microprocessor to determine a first pulse transit time, the first pulse transit time calculated by processing the electrical waveform and the first optical waveform;

using the microprocessor to determine a second pulse transit time, the second pulse transit time calculated by processing the electrical waveform and the second optical waveform;

processing the first pulse transit time and the second pulse transit time to determine a blood pressure value for the user;

taking a second derivative of at least one of the first optical waveform in and the second optical waveform, and then processing the second derivative to determine a property related to arterial compliance.