Microwave system for detecting gaseous emboli

• US 5,198,776 A
• Filed: 06/26/1991
• Issued: 03/30/1993
• Est. Priority Date: 06/26/1991
• Status: Expired due to Term

• Current Assignee: Microwave Medical Systems Incorporated (General Electric Company)
• Original Assignee: Microwave Medical Systems Incorporated (General Electric Company)
• Inventors: Carr, Kenneth L.
• Primary Examiner(s): Harvey, Jack B.
• Assistant Examiner(s): Regan, Maura K.
• Application Number:
  US07/721,107
• Time in Patent Office: 643 Days
• Field of Search: 324/639, 128/653.1, 128/DIG. 13, 604/50, 604/65, 333/26, 73/19.1, 73/19.01
• US Class Current: 324/639
• CPC Class Codes: A61M 5/365 Air detectors A61M5/1684 takes precedence; in extracorporeal blood circuits A61M1/3626
• CPC Class Codes: Y10S 128/13 Infusion monitoring

Abstract

Apparatus and a method for detecting the presence of incidental bubbles in liquid flowing in a tube. The system monitors the amplitude of microwave radiation from the liquid and recognizes when that amplitude drops in a manner characteristics of the presence of a bubble.

Claims

1. A system for detecting the passage of gaseous emboli through a portion of conduit having liquid contents, comprising:

(a) a microwave radiometer which detects energy in the microwave spectrum,

(b) a microwave waveguide which directs emitted microwave energy from the contents of the portion of the conduit to the radiometer,

(c) a signal conversion section which converts the energy at the radiometer into an output signal related to the amplitude of microwave radiation from the contents of the portion of the conduit,

(d) a source of a controlled reference signal,

(e) means of comparing said output signal with said controlled reference signal, and

(f) means of recognizing a change in the results of said comparison indicative of entry of a gaseous embolus into said portion of the conduit.

2. A system as recited in claim 1, wherein the liquid is a biologic fluid.

3. A system as recited in claim 1, wherein the liquid is blood.

4. A system as recited in claim 1, wherein the liquid is a biologic imaging fluid.

5. A method for detecting the passage of gaseous emboli through a portion of conduit having liquid contents, comprising the steps of:

(a) positioning a microwave radiometer which detects energy in the microwave spectrum,

(b) positioning the portion of the conduit in a microwave waveguide which directs microwave energy from the contents of the portion of the conduit to the radiometer,

(c) employing a signal conversion section which converts the energy at the radiometer into an output signal related to the amplitude of microwave radiation from the contents of the portion of the conduit,

(d) producing a controlled reference signal,

(e) comparing said output signal with said controlled reference signal, and

(f) recognizing a change in the results of said comparison indicative of entry of a gaseous embolus into said portion of the conduit.