Medical tube and apparatus for locating the same in the body of a patient

• US 5,902,238 A
• Filed: 05/02/1996
• Issued: 05/11/1999
• Est. Priority Date: 09/14/1993
• Status: Expired due to Term

• Current Assignee: University of Washington
• Original Assignee: University of Washington
• Inventors: Golden, Robert N., Silverstein, Fred E.
• Primary Examiner(s): Kamm, William E.
• Assistant Examiner(s): Evanisko, George R.
• Application Number:
  US08/644,446
• Time in Patent Office: 1,104 Days
• Field of Search: 128/653.1, 128/654, 128/899, 600/407, 600/424, 600/899
• US Class Current: 600/424
• CPC Class Codes: A61B 5/06 Devices, other than using radiation, for detecting or locating foreign bodies for removing same A61B17/50 ; determining position of probes within or on the body of the patient
• CPC Class Codes: A61B 5/062 using magnetic field
• CPC Class Codes: G01V 3/081 the magnetic field is produced by the objects or geological structures characterised by the method of magnetic field measurement G01R33/00

Abstract

A medical tube, apparatus and method for locating the medical tube within the body of a patient. The medical tube has a permanent magnet associated therewith and is capable of being located by a detection apparatus which senses the static magnetic field strength gradient generated by the magnet associated with the medical tube and indicates the value of the gradient to the user. In one embodiment, the magnet is associated with the distal end of the medical tube in a fixed orientation with a magnetic dipole pointing to the proximal end and parallel to a longitudinal axis of the medical tube such that polarity of the magnet'"'"'s static magnetic field as sensed by the detection apparatus indicates the orientation of the distal end of the medical tube with the body of a patient.

Claims

1. A system for detecting the location of a medical tube within a patient comprising:

a detection apparatus and a medical tube, wherein the medical tube comprises a tube or device suitable for insertion into the patient'"'"'s body and a permanent magnet associated with the medical tube, the medical tube having a proximal end and distal end, and the permanent magnet generating a static magnetic field of sufficient strength per unit volume to permit detection by the detection apparatus of the magnet'"'"'s static magnetic field when the medical tube is inserted into the patient'"'"'s body, and wherein the magnet is associated with the distal end of the medical tube in a fixed orientation with a magnetic dipole pointing to the proximal end and parallel to a longitudinal axis of the medical tube such that polarity of the magnet'"'"'s static magnetic field as sensed by the detection apparatus indicates the orientation of the distal end of the medical tube within the patient'"'"'s body, and wherein the medical tube is selected from the group consisting of a catheter and medical instrument, and wherein the detection apparatus comprises first and second magnetic field strength sensors for sensing magnetic field strength and providing first and second magnetic field strength signals, a sensor driver for providing a driver signal to said first and second magnetic field strength sensors configured geometrically to null detection of ambient homogeneous magnetic fields to a value of zero, and a visual display or speaker operatively connected to the first and second magnetic field strength sensors for allowing visual or audible indication of said first and second magnetic field strength signals received therefrom.

2. The medical tube of claim 1 wherein the magnet is permanently affixed to the medical tube.

3. The medical tube of claim 1 wherein the magnet is removably affixed to the medical tube.

4. The medical tube of claim 1 wherein the catheter is selected from the group consisting of a feeding tube, urinary catheter, dilating catheter, pH catheter and motility catheter.

5. The medical tube of claim 1 wherein the catheter is a feeding tube.

6. The feeding tube of claim 5 having a tip end, wherein the magnet is incorporated in the tip end of the feeding tube.

7. The medical tube of claim 1 wherein the catheter is selected from the group consisting of a nasogastric tube, endotracheal tube, stomach pump tube, wound drain tube, rectal tube, vascular tube, Sengstaken-Blakemore tube, colonic decompression tube and urological tube.

8. The medical tube of claim 1 wherein the medical instrument is selected from the group consisting of an endoscope and a colonscope.