Electrical probe

March 16, 1948.

2,437,697

L. KALOM

ELECTRICAL PROBE

Filed April 1, 1946

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Patented Mar. 16, 1948

2,437,697

UNITED STATES PATENT OFFICE

2,437,697

ELECTRICAL PROBE

Lawrence Kalom, Chicago, Ill.

Application April 1, 1946, Serial No. 658,725

Claims. (CL 128—2.1) (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 O. G. 757)

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to surgical probes and more particularly to electric probes.

In the practice of surgery foreign metal objects in the body of the patient (such as bullets, fragments of shrapnel, pieces of hypodermic needles, etc.) are very difficult to locate and continued probing frequently endangers the health, if not the life, of the patient. Often the surgeon does not know whether he is striking the metal object or bone that may be adjacent to it, since they may both give the same feeling of resistance. This naturally confuses the surgeon, and results in delaying the operation. Frequently there is a tendency on the part of the metal object to slide along the tissue planes, thus making necessary an unusually large incision which is very undesirable.

In my copending patent application, Serial No. 506,460, filed October 15, 1943, now abandoned, and entitled Surgical device, it is pointed out that the prior art devices of which I am aware have never been very successful. The main reason for their lack of success is that they embody electrodes of such type as to necessitate an excessive diametral dimension with the result that as the penetrating portion of the probe progressed beyond the subcutaneous tissue in search of the metal object, it did not readily cut through the fascia, fatty tissue, fibrous tissue and muscle. This condition is materially aggravated in cases where the metal object has been within the body for a considerable period of time and has therefore become encapsulated in a thick, fibrous sheath.

As was pointed out in the said copending application that another reason for the failure of the prior art devices of which I am aware is that the construction and arrangement of their electrodes is such that they must be contacted by the metal object at a critically precise angle before their function is complete.

It is among the objects of the present invention to provide an electric surgical probe with penetrating qualities which are an improvement over not only the prior patented art, but also the copending application referred to.

Another object is to further improve the ability of the electrodes to function over a relatively wide range of angles, thereby increasing even further the ease with which a foreign metal object may be located.

Still another object is further increased simplicity and decreased cost of manufacture and operation.

The invention, then, comprises the features 5 hereafter fully described, and as particularly pointed out in the claims, the following description and the annexed drawing setting forth in detail a certain illustrative embodiment of the invention, this being indicative of but one of a 10 number of ways in which the principle of the invention may be employed.

In the drawing:

Figure 1 is a side elevational view, mostly in section, of the complete device of the present 18 invention;

Figure 2 is an enlarged elevational view, mostly in section, of the lower end of the device of Figure 1;

Figure 3 is a fragmentary enlarged elevational ¢0 view of the probe or penetrating portion of the device;

Figure 4 is a view similar to that of the showing of Figure 3, but taken at clockwise rotational right angles with respect to the latter;

Figure 5 is a view similar to those of Figures 3 and 4, but taken at clockwise rotational right angles with respect to the showing of Figure 4; and

Figure 6 is an end view of the penetrating por30 tion of the device.

Referring more particularly to the drawing, the numeral 2 generally designates the probe or penetrating portion of the device of the present invention. More specifically, this element com35 prises a cylindrical tube of small diameter which is composed of a hard electrically-conductive substance such as iridio-platinum, hardened silver, steel, etc. .This tube 2 corresponds in size and shape with a conventional hypodermic nee40 die; that is, its external diameter may (for example) be of the magnitude of approximately 15 mils, with walls approximately 3 mils in thickness and, accordingly, a bore which is approximately 9 mils in diameter. The penetrating end, or outer 40 extremity, of the cylindrical tube 2 is provided with a very sharp cutting extremity and will be more fully described hereinafter.

The inner (and opposite) end of the cylindrical tube 2 snugly fits into an enlarged head 3 which 00 projects therefrom and provides on its interior an enlarged central cylindrical recess 4 the bottom of which has a coniform extension 6 which communicates with the said tube, as shown in Figure 2. A pair of superposed disks 7 of suitable SO electrical insulating material is disposed at the

2,437,697 junction of the cylindrical recess 4 with the coniform extension 6. An elongate rod 8 of an electrically conductive relatively hard metal is disposed to extend throughout the interior of the cylindrical tube 2, and it projects through the disks 7. The projecting end of the elongate rod 8 terminates In an enlarged head 9 which rests atop the upper of the superposed disks 7 and serves as an electrical contact in a manner, and for a purpose, which will later be described.

The diameter of the elongate rod 8 is considerably smaller than the inside diameter of the cylindrical tube 2, and a spaced electrically-insulated relationship between these instrumentalities is maintained by means of a suitable insulating medium 10. This electrical insulating medium may acceptably take the form of a suitable resin which is applied as one or more coatings. For this purpose I have found “Formvar” to be highly satisfactory, the same being the trade name of a polyvinyl formal resin product of the Shawinigan Products Corporation, New York, N. Y., and belonging to a class of resins known as “polyvinyl acetal resins” which are prepared by effecting partial or complete hydrolysis of a polyvinyl acetate, followed by (or simultaneously with) reaction of the hydrolysis product with an aldehyde. Such compositions possess high dielectric strength, and are commercially obtainable in plastic form.

Preferably, too, this electrical insulation fills the space between the bottom of the lower of the superposed disks 7 and the bottom of the coniform extension 6 of the cylindrical recess 4.

In addition to maintaining the aforesaid spaced electrically insulated relationship, the electrical insulating medium mentioned cements the tube 2, enlarged head 3 and rod 8 in firm assembled relationship.

The handle portion of the device of the present invention comprises a tubular flash-light case 15 provided with an interior insulating wall 15' and having an interiorly screw threaded bottom portion 16 into which there is fitted an exteriorly screw threaded hollow nipple 17. This hollow nipple 17 is provided with an upper central cylindrical recess 19 and a communicating lower central cylindrical recess 20.

Disposed within the lower cylindrical recess 20 is a sleeve 22 into which the upper end of the enlarged head 3 of the cylindrical tube 2 is adapted to telescope and lock in any suitable manner, such as the well known “Leurlok,” a product of Becton and Dickinson which is widely used as a connector between the needle and body portion of a hypodermic syringe. Mote specifically, this comprises a plurality of outwardly extending lugs 23 on the upper end of the enlarged head 3 (of the cylindrical tube 2) which are adapted to pass through registering apertures or slots in an inwardly extending fiange 24 at the lower end of the sleeve 22 in the lower cylindrical recess 20 of the hollow nipple 17. After the lugs 23 have passed the apertures or slots in the flange 24 the enlarged head 3 is rotated to permit the lower surfaces of said lugs to lie above and in contact with the upper surface of said flange.

Disposed in the upper central cylindrical recess 19 is a thimble 28 having a tubular extension 29 which depends downwardly into the lower cylindrical recess 20. Both the thimble 28 and its tubular extension 29 are made of an electrical insulating medium, for example Bakelite. Within the thimble 28 there is disposed an electrically conductive coiled spring 3i which makes contact on its lower end with the upper end of a slidable pin 32 which projects through and from the tubular extension 29 and carries on its projecting end a head 33 which is adapted to engage the head δ 9 on the upper end of the elongate rod 8 in the cylindrical tube 2. The upper end of the coiled spring 31 engages the base of a flash light battery 35 within the flash light case 15.

A ferrule 36 having a depending tubular ex10 tension 37 is disposed within the lower cylindrical recess 20 and serves to guide the tubular extension 29 of the thimble 28 into the enlarged central cylindrical recess 4 in the enlarged head 3 on the cylindrical tube 2.

In the foregoing manner electrical conductivity is maintained between the base of the flashlight 35 and the elongate rod 8 within the cylindrical tube 2.

As shown at the top of Figure 1 of the drawings, 20 a short cylindrical sleeve 40 is mounted in the flashlight case 15 immediately above the flashlight battery and within this sleeve 40 there is mounted a slidable ring 41, the latter carrying a bulb socket 42. A suitable bulb 44 is carried in the bulb socket 25 42 and the said bulb and the upper end of the flashlight case is closed by a translucent or transparent cap 45.

Either the flashlight bulb 44 and/or the cap 45 is colored as to cast a light which is readily 30 distinguishable in the bright, white light of a surgical operating room.

The use of the coiled spring 31 in conjunction with the slidable pin 32 to which it is soldered tends to make a firm contact between its head 33 35 and the head 9 on the upper end of the elongate rod 8. This spring also tends to take up any slack that may exist between the flashlight battery 35 and the bulb 44. The slide ring 41 permits movement so that the compression of the coiled spring 40 31 on the flashlight battery and the lamp bulb will take up the slack between these elements.

All joints which communicate with the outside (or atmosphere) are machined to render them waterproof, whereby the complete device 45 of the invention may, without disassembly, be sterilized simply by immersion in a cold sterilizing solution.

As previously mentioned, the penetrating end, or outer extremity of the cylindrical tube 2 is pro50 vided with a very sharp cutting extremity and actually in so doing it cooperates with the corresponding end of the elongate rod 8. The shapes of the cutting extremities of these elements constitute the most important feature of the present ₅₅ invention, and the same will be described immediately hereinafter.

As shown in Figures 3, 4 and 5, the operative end of the device of the invention comprises the coextensive termination of the cylindrical tube 2, ₆₀ the interiorly disposed elongate rod 8 and the insulating medium to which is disposed therebetween. In addition, two tapering portions are provided, one being of considerably greater angularity than the other, and each extending for ap_e5 proximately one-half the circumference of the cylindrical tube 2, and both of these tapering portions being rounded to provide a convex contour. These tapers are indicated at 47 and 48, the latter being the one of greater angularity and conse70 quently effective to form, an aperture in the wall of the cylindrical tube. 2 which exposes the adjacent surface of the elongate rod 8. These tapering portions 47 and 48 are preferably obtained by resort to simple grinding operations during 75 which the cylindrical tube 2 is partially rotated.

2,437,697

The preparation of the corresponding surfaces of the elements In the manner stated Immediately hereinbefore provides what would be a common point formed by the cylindrical tube 2 and the rod 8 except for the minute thickness of Insulating medium 10 which separates them. The coextension of the sharpened extremity of the rod 8 with the cutting extremity of the tube 2 enables them to bridge a metal object disposed In end-on relationship; while the curvilinear tapering disposed inwardly thereof provides extreme sensitivity in cases where the metal object is just outside the range of the relationship stated.

When the tube 2 and the rod 8 at the extremity of the probe are bridged by a metal object, a circuit is completed from the central terminal 50 of the flashlight battery 35 to the central contact 51 of the lamp 44, through the filament (not shown) of said lamp, to the outer threaded contact 44' of the lamp, thence through bulb socket 42, ring 4f, to sleeve 40, through case 15, to hollow nipple 17, and to ferrule 36, and sleeve 22 to head 3, to tube 2 and across the bridging metallic body (not shown) to the rod 8, to head 9, head 33, slidable pin 32, spring 31, and to the base of the flashlight battery 35. The lamp 44 is thus Illuminated when the tube 2 and rod 8 are bridged by the foreign metallic body.

I have found that excellent results may be obtained when the cylindrical tube 2 and the elongate rod 8 are composed of cold drawn stock that has been tempered at 1850° F. so as to develop a Brinell hardness value of between No. 580 and No. 620. The hardness of the probing extremity of the device is of utmost importance as it has been found that with softer steel probing around a bony area for about ten minutes will render the point quite blunt and therefore not within the objectives sought by the present invention.

Other modes of applying the principles of the invention may be employed, changes being made as regards the details described, providing the features stated in any of the following claims, or the equivalent of such be employed.

This application is a continuation-in-part of my copending application Serial No. 506,460, filed October 15, 1943, now abandoned.