Apparatus and method for non-invasively monitoring a subject's arterial blood pressure

• US 6,176,831 B1
• Filed: 07/20/1998
• Issued: 01/23/2001
• Est. Priority Date: 07/20/1998
• Status: Expired due to Fees

• Current Assignee: Tensys Medical Inc. (Recorders & Medicare Systems Pvt Ltd.)
• Original Assignee: Tensys Medical Inc. (Recorders & Medicare Systems Pvt Ltd.)
• Inventors: Voss, Gregory I., Finburgh, Simon E., Somerville, Alvis J.
• Primary Examiner(s): Nasser, Robert L.
• Application Number:
  US09/120,205
• Time in Patent Office: 918 Days
• Field of Search: 600/485, 600/806, 600/503
• US Class Current: 600/485
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers

Abstract

Apparatus is disclosed for non-invasively monitoring a subject'"'"'s blood pressure, in which a pressure sensor assembly that includes a pressure transducer is compressed against tissue overlying an artery, with sufficient force to compress the artery. A motor first servo control system optimizes the amount of artery compression, which occurs at a mean transmural pressure of about zero, by modulating one side of a lever arm compressing the assembly against the tissue, creating a pressure signal indicative of transmural pressure. Since different pressure effects are realized according to the amount of artery compression, an appropriate control signal can be produced that provides for a second motor to adjust the other side of the lever arm to provide the optimum compression of the assembly into the tissue overlying the artery. The apparatus is optimally positioned over an artery by including an ultrasonic blood flow sensor configured to sense the flow of blood under the pressure transducer.

Claims

1. Apparatus for non-invasively monitoring the pressure within a subject'"'"'s blood vessel, comprising:

a housing having a substantially planar face configured to compressively engage the tissue overlying the subject'"'"'s blood vessel, a chamber, and a recess;

a pressure transducer carried on the housing and configured to produce a pressure signal indicative of the pressure applied against it, the pressure transducer further being sized to be received within the chamber of the housing;

a coupling device configured to urge the housing into compressive engagement with the tissue overlying a subject'"'"'s blood vessel, to compress the vessel and ensure that pressure variations within the vessel are coupled through the tissue to the pressure transducer; and

a blood vessel sensor sized to be received within the recess of the housing and configured to detect the presence of the blood vessel in the space adjacent to the housing, whereby the apparatus can be moved to place the pressure transducer is in a prescribed position overlying the subject'"'"'s blood vessel.

2. Apparatus as defined in claim 1, wherein:

the pressure transducer has a substantially planar face that is oriented substantially parallel with the planar face of the housing; and

the blood vessel sensor is an ultrasonic transducer having a substantially planar face that is oriented at a prescribed acute angle relative to the planar face of the housing.

3. Apparatus as defined in claim 2, wherein the substantially planar face of the ultrasonic transducer is oriented at an angle of about 35 degrees relative to the planar face of the housing.

4. Apparatus as defined in claim 2, wherein:

the recess of the housing is configured such that the ultrasonic transducer is spaced above the planar face of the housing; and

the apparatus further comprises a lubricant disposed on the planar face of the housing, for enhancing the coupling between the ultrasonic transducer and the subject'"'"'s blood vessel.

5. Apparatus for non-invasively monitoring the pressure within a subject'"'"'s blood vessel, comprising:

a housing;

a pressure transducer carried on the housing and configured to produce a pressure signal indicative of the pressure applied against it;

a coupling device configured to urge the housing into compressive engagement with the tissue overlying a subject'"'"'s blood vessel, to compress the vessel and ensure that pressure variations within the vessel are coupled through the tissue to the pressure transducer; and

a blood vessel sensor carried on the housing and configured to detect the presence of the blood vessel in the space adjacent to the housing, whereby the apparatus can be moved to place the pressure transducer is in a prescribed position overlying the subject'"'"'s blood vessel;

wherein the housing is configured to carry the pressure transducer and the blood vessel sensor in positions such that the space adjacent to the housing in which the blood vessel sensor detects the blood vessel is directly aligned with the space adjacent to the pressure transducer.

6. Apparatus for non-invasively monitoring the pressure within a subject'"'"'s blood vessel, comprising:

a housing having at least one inner rigid portion an outer, compliant portion that encircles the at least one inner rigid portion;

a pressure transducer carried on the housing and configured to produce a pressure signal indicative of the pressure applied against it;

a coupling device configured to urge the housing into compressive engagement with the tissue overlying a subject'"'"'s blood vessel, to compress the vessel and ensure that pressure variations within the vessel are coupled through the tissue to the pressure transducer; and

a blood vessel sensor carried on the housing and configured to detect the presence of the blood vessel in the space adjacent to the housing, whereby the apparatus can be moved to place the pressure transducer is in a prescribed position overlying the subject'"'"'s blood vessel;

wherein the at least one rigid portion of the housing carries the pressure transducer and the blood vessel sensor, and the inner and outer portions cooperate to define a substantially planar face configured to compressively engage the tissue overlying the subject'"'"'s blood vessel.

7. Apparatus for non-invasively monitoring the pressure within a subject'"'"'s blood vessel, comprising:

a housing;

a pressure transducer carried on the housing and configured to produce a pressure signal indicative of the pressure applied against it;

a coupling device configured to urge the housing into compressive engagement with the tissue overlying a subject'"'"'s blood vessel, to compress the vessel and ensure that pressure variations within the vessel are coupled through the tissue to the pressure transducer; and

a plurality of blood vessel sensors carried on the housing, the plurality of sensors being disposed in an array and configured to detect the presence of the blood vessel in the space adjacent to the housing, the array further being configured to determine a direction to move the apparatus to place the pressure transducer is in a prescribed position overlying the subject'"'"'s blood vessel.

8. Apparatus as defined in claim 7, and farther comprising:

an adjustment mechanism configured to adjust the position of the pressure transducer toward a prescribed position overlying the subject'"'"'s blood vessel; and

a controller configured to control the adjustment mechanism.

9. Apparatus for non-invasively monitoring the pressure within a subject'"'"'s blood vessel, comprising:

a housing;

a pressure transducer carried on the housing and configured to produce a pressure signal indicative of the pressure applied against it;

an adjustment mechanism configured to adjust the position of the pressure transducer;

a coupling device configured to urge the housing into compressive engagement with the tissue overlying a subject'"'"'s blood vessel, to compress the vessel and ensure that pressure variations within the vessel are coupled through the tissue to the pressure transducer; and

a blood vessel sensor carried on the housing and configured to detect the presence of the blood vessel in the space adjacent to the housing, whereby the adjustment mechanism and apparatus can be utilized to place the pressure transducer is in a prescribed position overlying the subject'"'"'s blood vessel.

10. A method for non-invasively monitoring the pressure within a subject'"'"'s blood vessel, comprising the steps of:

providing a pressure sensing apparatus that includes;

(i) a housing having a substantially planar face configured to compressively engage the tissue overlying the subject'"'"'s blood vessel, the housing further including a chamber and a recess;

(ii) a pressure transducer carried on the housing and sized to be received within the chamber of the housing, the pressure transducer being configured to produce a pressure signal indicative of the pressure applied against it; and

(iii) a blood vessel sensor carried on the housing and sized to be received within the recess of the housing, the blood vessel sensor being configured to produce a signal indicative of the presence of a vessel in the space adjacent to the housing;

controllably moving the housing across the tissue near a subject'"'"'s blood vessel until the signal produced by the blood vessel sensor indicates that the housing has reached a prescribed position overlying the subject'"'"'s blood vessel, the housing being oriented such that an axis connecting its chamber and its recess is substantially parallel with the subject'"'"'s blood vessel; and

urging the housing into compressive engagement with the tissue overlying a subject'"'"'s blood vessel, to compress the vessel and ensure that pressure variations within the vessel are coupled through the tissue to the pressure transducer carried on the housing.

11. A method for non-invasively monitoring the pressure within a subject'"'"'s blood vessel, comprising the steps of:

providing a pressure sensing apparatus that includes a housing having a planar face, a pressure transducer carried on the housing and configured to produce a pressure signal indicative of the pressure applied against it, and an ultrasonic transducer carried on the housing and spaced above the planar face thereof, the ultrasonic transducer being configured to produce a signal indicative of the presence of a vessel in the space adjacent to the housing;

placing a lubricant on at least a portion of the planar face of the housing, thereby enhancing the coupling between the ultrasonic transducer and the subject'"'"'s blood vessel;

controllably moving the housing across the tissue near a subject'"'"'s blood vessel until the signal produced by the blood vessel sensor indicates that the housing has reached a prescribed position overlying the subject'"'"'s blood vessel; and

urging the housing into compressive engagement with the tissue overlying a subject'"'"'s blood vessel, to compress the vessel and ensure that pressure variations within the vessel are coupled through the tissue to the pressure transducer carried on the housing.

12. A method for non-invasively monitoring the pressure within a subject'"'"'s blood vessel, comprising the steps of:

providing a pressure sensing apparatus that includes;

(i) a housing forming a compression surface;

(ii) a pressure transducer having a compression surface and being carried on the housing such that the compression surfaces of the pressure transducer and housing are flush, the pressure transducer further being configured to produce a pressure signal indicative of the pressure applied against it; and

(iii) a blood vessel sensor carried on the housing and configured to produce a signal indicative of the presence of a vessel in the space adjacent to the housing;

controllably moving the housing across the tissue near a subject'"'"'s blood vessel until the signal produced by the blood vessel sensor indicates that the housing has reached a prescribed position overlying the subject'"'"'s blood vessel; and

urging the compression surface of the housing and the pressure transducer into compressive association with first and second portions of the tissue overlying a subject'"'"'s blood vessel, respectively, the first portion surrounding the second portion, to compress the vessel and ensure that pressure variations within the vessel are coupled through the tissue to the pressure transducer carried on the housing.

13. A method as defined in claim 12, wherein, in the step of providing, the compression surface of the housing includes an inner section and an outer section, the outer section surrounding the inner section, and the outer section being more compliant that the inner section.

14. A method as defined in claim 12, wherein, in the step of providing, the shape of the compression surface of the housing is longer than it is wide, and in the step of urging, the shape is oriented relative to the blood vessel such that the vessel runs in the compression surface'"'"'s long direction.