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

• US 5,964,711 A
• Filed: 04/02/1998
• Issued: 10/12/1999
• Est. Priority Date: 12/13/1996
• Status: Expired due to Fees

• Current Assignee: Tensys Medical Inc. (Recorders & Medicare Systems Pvt Ltd.)
• Original Assignee: Vitalwave Corporation (Recorders & Medicare Systems Pvt Ltd.)
• Inventors: Voss, Gregory I., Somerville, Alvis J.
• Primary Examiner(s): Nasser, Robert L.
• Application Number:
  US09/054,288
• Time in Patent Office: 558 Days
• Field of Search: 600/485, 600/500-503, 600/561
• US Class Current: 600/485
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence

Abstract

Apparatus is disclosed for non-invasively monitoring a subject'"'"'s blood pressure, in which a flexible diaphragm that encloses a fluid-filled chamber is compressed against tissue overlying an artery, with sufficient force to compress the artery. A first, relatively slow servo control system optimizes the amount of artery compression, which occurs at a mean transmural pressure of about zero, by modulating the volume of fluid within the chamber and noting the resulting effect on the pressure within the chamber. Since different pressure effects are realized according to the amount of artery compression, an appropriate control signal can be produced that provides the optimum mean diaphragm pressure. In addition, a second, relatively fast servo control system supplies the fluid to and from the chamber, so as to compensate for pressure variations within artery. This minimizes variations in the artery'"'"'s effective diameter, whereby the pressure within the fluid-filled chamber closely follows the actual arterial pulse waveform.

Claims

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

a pressure sensor assembly that produces a pressure signal indicative of the pressure applied against it;

a coupling device configured to urge the pressure sensor assembly into compressive engagement with 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 sensor assembly; and

a controller that controllably modulates the position of the pressure sensor assembly relative to the subject'"'"'s blood vessel with a periodic signal having a frequency substantially greater than the frequency of the subject'"'"'s expected heartbeat, wherein the controller monitors the pressure signal to produce a plurality of pressure waveforms, each corresponding to a different phase of the periodic signal.

2. Apparatus as defined in claim 1, wherein the controller further is configured to select the particular one of the pressure waveforms that derives from a transmural pressure of substantially zero.

3. Apparatus as defined in claim 2, wherein the controller further is configured to select the particular one of the pressure waveforms that derives from a transmural pressure of substantially zero by selecting the particular waveform for which the pressure signal at systole differs from the pressure signal at diastole by a maximum amount.