United States Patent 3847157

A tube structure is disclosed, for use within living tissue, incorporating a magnetic element whereby the location and length of the tube within tissue may be readily detected. In one disclosed form, the tube is seamless, flexible and is formed of non-fibrous imperforate material containing ferromagnetic material for magnetic detection. In the forms as disclosed, the ferromagnetic material comprises an integral metal strip, particulate or segments of material extending along the length of the tube. A separate grounding strip may also be included in a tube as disclosed, that is radio-opaque for X-ray detection. The tube generally is tapered to define a distal end. A magnetic detector for sensing the tube is also disclosed utilizing a movably supported gapped magnetic toroid.

Caillouette, James C. (Pasadena, CA)
Johnson, Paul E. (San Marino, CA)
Application Number:
Publication Date:
Filing Date:
Primary Class:
Other Classes:
138/118, 600/435, 600/581
International Classes:
A61B5/06; A61M25/00; A61M25/01; A61M16/04; (IPC1-7): A61M25/00
Field of Search:
View Patent Images:

Other References:

RCA Tech. Notes, June 1966, RCA TN No. 675, Morey.
Primary Examiner:
Truluck, Dalton L.
Attorney, Agent or Firm:
Nilsson, Robbins, Bissell, Dalgarn & Berliner
What is claimed is

1. An externally detectable tube structure for use within living tissue, as to establish an access passage comprising:

2. A tube structure according to claim 1 wherein said ferromagnetic material is magnetized by domains of a dominant sense of magnetism along the entire substantial length thereof and aligned with said elongated tube.

3. A tube structure according to claim 1 wherein said ferromagnetic material comprises a continuous strip that extends substantially the full length of said tube.

4. A tube structure according to claim 3 wherein said ferromagnetic material is magnetized by domains of a dominant sense of magnetism and wherein said dominant sense of magnetism aligns to the elongate tube.

5. A tube structure according to claim 1 wherein said ferromagnetic material comprises separate spaced-apart segments of particulate material defining a strip.

6. A tube structure according to claim 5 wherein said tube material is transparent and said ferromagnetic material is confined to a defined radial segment in the wall of said tube.

7. A tube structure according to claim 1 wherein said ferromagnetic material comprises an integral wire extending along the elongated dimension of said tube.

8. A tube structure according to claim 1 wherein said tube material is transparent and further includes an electrically conductive strip extending substantially the full length of said tube and from the interior to the exterior of the wall of said tube.

9. A tube structure according to claim 1 wherein one end of said tube is of reduced cross section to define a distal end.


The need frequently arises to place medico-surgical tubes, e.g., catheters, within various living-tissue spaces. In placing such tubes, it is sometimes critically important that the attending person have knowledge with respect to the precise location of the tube. In that regard, it previously has been proposed to provide tubes that are partially or completely X-ray opaque. In using such tubes, the precise position of a tube is indicated by X-ray presentations. However, a basic difficulty with such procedures and techniques resides in the complexity of the required equipment and a concern regarding repeated or prolonged X-ray irradiation of living tissue.

Generally, there is a substantial current trend toward increased activity by paramedical personnel in emergency situations. The risks attendant such practice are related to the limitations of paramedical personnel and the fact that they often must work in locations where only simple and rudimentary equipment is available. One piece of equipment commonly provided for use by paramedical personnel is a medico-surgical tube. For example, such tubes are often necessary to restore respiration for one reason or another. These considerations emphasize the need for a simple tube, the location and length of which within living tissue can be readily determined, without irradiating the tissue or utilizing other complex equipment.

Another consideration regarding medico-surgical tubes relates to the electrical characteristics. There is concern both with regard to electrical leakage currents from associated equipment that might endanger a patient and static electricity that may produce a sufficient spark to ignite combustible substances, e.g., gas. Fatal arrhythmias can result from either form of electrical activity. Accordingly, a need exists for a medico-surgical tube, the location of which is readily detectable as indicated above, and additionally which has certain electrical characteristics. Other desirable characteristics for a medico-surgical tube include flexibility and transparency to permit observing the tube interior.

In general, the present invention relates to a medico-surgical tube system whereby the location of a tube within living tissue may be simply, accurately and easily determined. Specifically, the system includes a tube of flexible, transparent imperforate material carrying a strip of continuous or discretely placed segments of magnetic material for actuating a magnetic indicator. In the disclosed embodiments, a strip of magnetic material is provided to extend along the length of the tube and comprises magnetizable material having a remanent magnetic flux density that is relatively high and which is magnetized with a pattern so as to be readily detected outside the living tissue. The magnetizable material may be provided in a form to accomplish desirable electrical characteristics or a separate conductive strip may be provided. The location of the tube is manifest by a movably mounted permanent magnet housed for convenient placement contiguous to the living tissue.


In the drawing, which constitutes a part of this specification, an exemplary embodiment demonstrating various objectives and features hereof is set forth as follows:

FIG. 1 is a diagrammatic view illustrative of the use of a system constructed in accordance with the present invention;

FIG. 2 is a plan view of one form of tube structure in accordance with the present invention;

FIG. 3 is an enlarged sectional view taken along line 3--3 of FIG. 2;

FIG. 4 is a view similar to FIG. 3 illustrating an alternative tube construction;

FIG. 5 is a view similar to FIG. 3 illustrating still another alternative tube construction;

FIG. 6 is a fragmentary view similar to FIG. 2 illustrating still a further alternative tube construction;

FIG. 7 is a plan view of an indicator constructed in accordance with the present invention; and

FIG. 8 is a central vertical sectional view taken through the indicator of FIG. 7.


As required, a detailed illustrative embodiment, deemed to be the best form of the invention for that purpose, is disclosed herein. The embodiment exemplifies the invention which may be constructed in various other forms, some of which may be quite different from the disclosed illustrative embodiment. However, specific structural and functional details disclosed herein are representative and in that regard provide a basis for the claims herein which define the scope of the invention.

Referring initially to FIG. 1, a human subject S is suggested along with indications of lungs L and air passages including a right bronchial tube 12, a left bronchial tube 14 and a trachea 16. Also, as indicated in FIG. 1, a medico-surgical tube T is shown passing through the trachea 16 and the right bronchial tube 12 to enter the right lung L. The position of the tube T is indicated by an indicator I which is as illustrated in FIG. 1, located on the chest of the subject S.

In considering an exemplary use of the present system, the tube T is placed within the subject S for the extraction of fluid from the lung cavity. It is to be recognized that the tube hereof is also useful in other ways, e.g., vascular, gastrointestinal, genitourinary, and so on. It is apparent that the tube T may substantially close the receiving bronchial tube, e.g., bronchial tube 12. Frequently, a subject S has lost the use of one lung as a result of the accumulation of fluid. Consequently, if the tube T (being placed for the purpose of removing the fluid) enters the bronchial tube of the single functioning lung, the subject S may lose all breathing capacity.

In accordance with the system of the present invention, the position of the tube T is manifest by the indicator I during the period of insertion. If the tube deviates in an undesired direction, the fact is promptly manifest by the indicator I, permitting corrective action to be taken. Detailed consideration will now be given to the structure of the tube T as well as the indicator I, pursuant to presenting the basis for a complete understanding of the system.

The tube T is a seamless, imperforate, elongated medico-surgical tube having a substantially uniform cross section except for a reducing taper at the distal end 20 and a slight enlargement or flare at the opposed end 22. The taper at the distal end 20 is helpful in probing and additionally is cooperative in interconnecting a series of tubes.

The tube is smooth at both the internal wall 24 (FIG. 3) and the external wall 26. Continuing to view the tube in cross section (FIG. 3) a radial segment comprises a strip 28 (FIG. 2) extending the full length of the elongated tube T and fully occupying a space between the internal wall 24 and the external wall 26. The non-strip portion 30 of the tube may be formed of clear or transparent plastic to afford a view of the tube contents or may be radio opaque for X-ray detection. The strip 28 may comprise similar plastic containing a concentration of ferromagnetic particles. For example, fine particles of magnetic material comprising approximately 80 percent nickel and 20 percent iron may be employed to provide a strip with retentive magnetic characteristics. Generally, if the strip 28 is to render the tube T conductive, the concentration of the particles should be relatively high.

In reducing the tube T, extrusion techniques may be employed as to form vinyl plastic material. Such techniques are well known in the plastics industry and are not deemed significant for disclosure herein. After formation of the tube, the strip 28 is magnetized along the entire length of the tube T to attain a dominant magnetic pattern that has a uniform sense. For example, the magnetic pattern may be with the distal end 20 as the north pole of the magnet while the opposed end 22 is magnetized as the south pole. Of course, various magnetizing techniques may be employed to accomplish such a pattern, as for example, placing the ends of the tube T in alignment contiguous to the ends of a powerful electromagnet so that the strip 28 is an element in a single magnetic circuit and is subjected to considerable magnetic flux.

In using the tube T after magnetization, it is significant that the magnetic field provided by the strip 28 as well as the inherent magnetic material in the strip provide the basis for sensing the location of the tube T. The sensor or indicator I as disclosed herein includes a housing 40 (FIG. 6) that is pointed along one plane, however, otherwise is of parallelepiped configuration. The upper surface 42 of the housing 40 provides an instrument display for indicating alignment with or position of the strip 28 in the tube T. As described, the housing 40 is tapered to a point 44 at the forward end. The upper surface 42 defines a window 46 through which a magnet 48 is exhibited. The magnet 48 carries a meter mark 50. Displacement of the meter mark 50 from alignment with an index mark 52 indicates a position of the tube T in the proximity of indicator I.

The magnet 48 in the indicator I is in a toroid form (defining a non-magnetic gap 54) and is concentrically supported by a coil spring 56 the center of which is affixed to a lateral post 58 that is anchored in the housing 40. When the indicator I is independent of substantial magnetic fields (or magnetic medium) the gap 54 is held in a quiescent position substantially as indicated in FIG. 7, resulting in the meter mark 50 (FIG. 6) being aligned with the index mark 52.

In using the indicator I, the bottom surface 60 is usually separated from the strip 28 by a section of living tissue 61. However, upon the flux field of the strip 28 encountering the flux field of the magnet 48, the latter is displaced counterclockwise (as indicated by the arrow 63) toward a position in which the strip 28 would close the non-magnetic gap 54. With such displacement, the meter mark 50 (FIG. 6) is moved forward from the index mark 52 indicating that the strip 28 (and accordingly the tube T) has been sensed. It may, therefore, be seen that the indicator I may be variously moved over the subject S (FIG. 1) to follow or indicate the position of a tube T.

As suggested above, the T may take various forms other than with the strip 28 of magnetic substance. In one alternative construction (FIG. 4) the tube may be a clear, somewhat cylindrical elongated body 65 into which a thin wire 66 of magnetic material is embedded. Additionally, a segmental strip 68 of conductive material, e.g., carbon, extends the full length of the tube T. In such a structure, the transparent body 65 affords a view of the interior of the tube. The wire 66 is magnetized as described, along a single polarity orientation for effective sensing. Thus, the desired electrical characteristic for the tube is provided by the strip 68 which extends completely through the tube and along its entire length.

With regard to small tubes, it may be desirable to provide a somewhat-uniform extrusion of plastic containing a dispersion of magnetic material. A form of such a tube is depicted in FIG. 5 and essentially consists of a homogeneous mixture of particle magnetic material in a carrier, as for example, of plastic.

As still another alternative, the tube may be as illustrated in FIG. 2; however, altered by the magnetic strip being in the form of slugs or segments 71 (FIG. 6). Specifically, the segments 71 are spaced apart by a predetermined distance D so as to provide another source of information in the use of a magnetic detector. Of course, the length of the segments 71 is also predetermined.

Of course, other forms of tubes may be employed in accordance with the teachings hereof to accomplish an effective structure for use within living tissue and which may be simply and easily located to define both position and path. Consequently, the scope hereof shall not be determined with limitations relating to the embodiment set forth herein, rather, however, shall be defined by the claims as set forth below.