Apparatus and method for blood pressure measurement by touch

• US 20070167844A1
• Filed: 11/29/2006
• Published: 07/19/2007
• Est. Priority Date: 11/29/2005
• Status: Abandoned Application

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Shaltis, Phillip, Asada, Haruhiko, Reisner, Andrew, Marinkovic, Aleksandar
• Application Number:
  US11/605,935
• Publication Number:
  US 20070167844A1
• Time in Patent Office: Days
• US Class Current: 600/485
• 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 5/02255 the pressure being controlled by plethysmographic signals, e.g. derived from optical sensors
• CPC Class Codes: A61B 5/6806 Gloves
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6838 Clamps or clips

Abstract

An arterial blood pressure apparatus and methods for using the apparatus are disclosed. The apparatus has a force transfer element for applying unidirectional force to a body part of the subject and a pressure sensor for generating a signal based on the unidirectional force. Multiple degrees of force may be applied simultaneously or serially. The apparatus also has a second sensor for generating a signal associated with blood volume within a blood vessel of the body part and a processor for inferring arterial blood pressure from the force sensor signal and the second sensor. The apparatus may take the form of a glove or a wand.

Claims

1. An apparatus for measuring arterial blood pressure in a subject, the apparatus comprising:

a. a force transfer element for applying unidirectional force to a body part of the subject;

b. a first sensor detecting a signal in response to the unidirectional force;

c. a second sensor detecting a signal associated with blood volume within a blood vessel of the body part; and

d. a controller for inferring arterial blood pressure from the sensor signals.

2. An apparatus according to claim 1, wherein the first sensor generates the signal based on mechanical reaction against a caregiver.

3. An apparatus according to claim 1, wherein the first sensor is a force sensor.

4. An apparatus according to claim 3, wherein the force sensor is a pressure sensor.

5. An apparatus according to claim 3, wherein the force sensor serves as the second sensor.

6. An apparatus according to claim 1, wherein the second sensor is a plethsmograph.

7. An apparatus in accordance with claim 6, wherein the plethsmograph is a photoplethysomgraph.

8. An apparatus in accordance with claim 1, wherein the force transfer element is a glove.

9. An apparatus according to claim 1, wherein the force transfer element is characterized by a plurality of pressure regions each having a distinctive compliance.

10. An apparatus according to claim 1, wherein the force transfer element is a wand.

11. An apparatus according to claim 3, having a plurality of force sensors.

12. An apparatus according to claim 11, wherein each force sensor is coupled to a mount having a different compliance characteristic.

13. An apparatus according to claim 1, wherein the signal associated the second sensor measures oscillations of the artery.

14. An apparatus according to claim 13, wherein the controller determines the arterial blood pressure based in part upon the oscillations measured by the second sensor.

15. An apparatus according to claim 1, wherein systolic blood pressure is determined by the controller based in part on the signal of the second sensor.

16. An apparatus according to claim 1 wherein mean arterial blood pressure is determined by the controller based in part on the signal of the second sensor.

17. An apparatus according to claim 1, wherein diastolic blood pressure is determined by the controller based in part on the signal of the second sensor.

18. An apparatus according to claim 1, wherein the controller produces feedback for the caregiver.

19. An apparatus according to claim 18, wherein the feedback indicates repositioning of the apparatus relative to the artery.

20. An apparatus according to claim 18, wherein the feedback indicates that a caregiver should change the applied unidirectional force.

21. An apparatus according to claim 1, wherein the controller includes a user input for accounting for hydrostatic pressure.

25. A method according to claim 14 wherein the applied pressure is measured by a pressure sensor.

22. A method for measuring arterial blood pressure in a subject, the method comprising:

a. applying a pressure in a force direction substantially normal to the surface of a body part of the subject;

b. measuring the pressure applied;

b. detecting a sensor signal at the surface of the body part;

c. inferring arterial blood pressure from the sensor signal and the applied pressure.

23. A method according to claim 22, wherein the sensor signal detects oscillations of the artery.

24. A method according to claim 22, wherein systolic blood pressure is determined based at least on the sensor signal.

26. A method according to claim 22 wherein inferring arterial blood pressure occurs in a controller.

27. A method according to claim 22 wherein the sensor signal is sensed by a photoplethysomgraph.

28. A method according to claim 22 further comprising:

placing a glove on a hand of the caregiver wherein the glove includes a pressure sensor for measuring the applied pressure, a photo sensor for detecting the sensor signal, and a light source.

29. A method according to claim 22, wherein pressure is applied in a force direction substantially normal to the body part of the subject by a wand and wherein the wand includes a sensor unit having a light source, a photo sensor, and a pressure sensor.

30. A method according to claim 22, further comprising:

measuring hydrostatic pressure;

wherein the arterial blood pressure is also inferred based on the hydrostatic pressure.

31. A method according to claim 22 wherein applying a pressure in a direction normal to a body part results from a force transfer element;

and;

based in part on the detected sensor signal providing feedback to a caregiver to reposition the force transfer member.