[54] METHOD FOR DETECTING AIR EMBOLI IN THE BLOOD IN AN INTRACORPOREAL BLOOD VESSEL
[75] Inventors: Peter S. Colley, Seattle; Roy W.
Martin, Redmond, both of Wash.
[73] Assignee: The Board of Regents of the
University of Washington, Seattle,
Wash.
[21] Appl. No.: 70,356
[22] Filed: Aug. 28, 1979
[51] Int. C1.3 A61B 10/00
[52] U.S. CI 128/661; 128/696
[58] Field of Search 128/660-663,
128/349 R, 696; 73/19, 23-24, 861.41
[56] References Cited
U.S. PATENT DOCUMENTS
3,640,271 2/1972 Horton 128/662
3,921,622 11/1975 Cole 73/19
4,112,735 9/1978 McKnight 73/19
4,112,773 9/1978 Abts 73/19
4,122,713 10/1978 Stasz et al 73/19
OTHER PUBLICATIONS
Fairbank, W. M. et al., "A New Non-Invasive Tech-
nique for Cardiac Pressure Measurement: Reson Scat-
tering of UTS from Bubbles", IEEE BME Trans, vol.
24 No. 2, Mar. 1977, pp. 107-110.
Furness, A. et al., "Detection of Bubbles in Blood Ves-
sels and Extra-Corporeal Circuits," Med. & Biol.
Engrg. & Const. 1979, vol. 17, pp. 534-535.
Primary Examiner—Robert W. Michell
Assistant Examiner—Francis J. Jaworski
Attorney, Agent, or Firm—Christensen, O'Connor,
Johnson & Kindness
[57] ABSTRACT
A system for detecting and quantifying air emboli in blood vessels which uses either an intravascular catheter 22 or an esophageal catheter 50. In a preferred embodiment, the intravascular catheter includes an elongated cylindrical tube of flexible material, the tube having a tip 22A and having formed therein an axial aspiration lumen 26 and a second axial lumen 28. An ultrasonic transducer 24, comprising an annular, cylindrical ring of piezoelectric material, is fitted over and secured to the tube adjacent its tip. A microcoaxial cable passes through lumen 28 and is electrically interconnected with the ultrasonic transducer. In a preferred embodiment, the esophageal catheter includes a substantially cylindrical member 54 on which is fitted an ultrasonic transducer 52 comprising an annular, cylindrical ring of piezoelectric material. An elongated tube 58 is secured to the substantially cylindrical member, and a microcoaxial cable 62 passes through tube 58 and the substantially cylindrical member and is electrically connected to the ultrasonic transducer. In use, the intravascular catheter is positioned within a desired blood vessel after percutaneous insertion, and the esophageal catheter is positioned within the esophagus below the bifurcation of the trachea. A pulsed Doppler circuit (FIG. 9) energizes the transducer and provides a Doppler signal from return signals generated by the transducer as a result of returns of transmitted ultrasonic energy. A circuit (FIGS. 10 and 11) processes the Doppler signal to obtain various information useful in the diagnosis of air emboli.
9 Claims, 11 Drawing Figures
