Apparatus and method for locating a medical tube in the body of a patient

United States Patent [i9]

Golden et al.

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US005622169A [ii] Patent Number: 5,622,169 [45] Date of Patent: Apr. 22, 1997

[54] APPARATUS AND METHOD FOR

LOCATING A MEDICAL TUBE IN THE
BODY OF A PATIENT

[75] Inventors: Robert N. Golden, Kirkland; Fred E.

Silverstein, Seattle, both of Wash.

[73] Assignee: University of Washington, Seattle,
Wash.

[21] Appl. No.: 307,230
[22] Filed: Sep. 14, 1994

Related U.S. Application Data

[63] Continuation-in-part of Ser. No. 121,929, Sep. 14,1993, Pat. No. 5,425,382.

[51] Int. CI.6 A61B 5/05

[52] U.S. CI 128/653.1; 128/899

[58] Field of Search 600/12; 128/630,

128/631, 653.1, 207.14, 653.4, 207.15, 654, 772, 899, 200.28; 324/207.17, 207.28, 329, 231; 340/572, 537

[56] References Cited

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FOREIGN PATENT DOCUMENTS

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OTHER PUBLICATIONS

Williams et al. abstract, "The Localisation of Enteral Tubes Using a Novel Non-Radiological Technique," British Society of Gastroenterology (Mar. 1992). Gaston et al., "Experimental Studies in Dogs and Prospects of Application," Journal of Neuroradiology 15(2):137-147, 1988.

Ram and Meyer, "Heart Catheterization in a Neonate by Interacting Magnetic Fields: A New and Simple Method of Catheter Guidance": Catheterization and Cardiovascular Diagnosis 22:317-319 (1991).

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1970.

Primary Examiner—Angela D. Sykes
Assistant Examiner—Samuel Gilbert
Attorney, Agent, or Firm—Seed and Berry LLP

[57] ABSTRACT

There is disclosed an apparatus and method for locating a medical tube within the body of a patient. The medical tube is located by a detection apparatus which senses the static magnetic field strength gradient generated by a magnet associated with the medical tube and indicates the value of the gradient to the user. The detection apparatus is moved about the body of the patient until the greatest gradient magnitude is indicated. The detection apparatus distinguishes the field strength of the magnet associated with the medical tube from the earth's field strength by sensing the magnet's field strength at two different distances from the magnet.

25 Claims, 7 Drawing Sheets