US 3606669 A
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Description (OCR text may contain errors)
Sept. 2, 1971 M. s. KEMBLE METHOD OF MAKING TRACHEAL TUBE DEVICE Filed May 26, 1969 United States Patent 3,606,669 METHOD OF MAKING TRACHEAL TUBE DEVICE Mern S. Kemble, Clarion, Pa., assignor to Philip Morris Incorporated, New York, N.Y. Filed May 26, 1969, Ser. No. 827,771 Int. Cl. B23p 19/00; 1529c 17/02; A61b 17/24 US. Cl. 29- 434 4 Claims ABSTRACT OF THE DISCLOSURE A tracheal tube device having an outer tube and an inner tube insertable in and removable with respect to the outer tube is made by a method in which the outer tube is cast in initially straight form from a thermoplastic material and before cooling is bent into the desired radius and upon cooling the tube is relatively rigid and stiff in the pre-set curved form; the inner tube likewise being cast in a straight form but of an elastomeric material which remains flexible when cooled. In use the inner tube is inserted in the outer tube and readily conforms to the radius and shape thereof. The inner tube is disposable and is easily removed and replaced by a new sterile tube.
BACKGROUND 'OF THE IINVENTION The present invention concerns devices employed in tracheotomy. Instruments of that general character are adapted to be inserted into the throat or trachea of a patient to provide an airway while surgical operations are performed in the area and for treatment thereof in conjunction with the operation and subsequently, including a the removal of mucus and foreign matter. Such instruments may be employed also in the treatment of chronic conditions. A great variety of such instruments, sometimes called trachea tubes, have been proposed over a long period of time. In some instances the instrument tube and shaped to facilitate the initial insertion of the tube into the throat.
An. early patent showing a tracheotomy instrument comprising inner and outer tubes is Hartstein 507,813 granted Oct. 31, 1893. In this instance the outer and inner tubes are each evidently formed initially with a fixed .pre-set radius which is the same for both. Representative later patents are Nichols 2,765,792 and 3,088,466;'Cohen 2,786,469; Koenig 3,169,529 and Stebleton 3,334,631.
These later patents contain various statements regarding making the tubes of plastic and in some such as in the patents to Koenig and Stebleton and the later patent to Nichols reference is made to the material being resilient or soft and flexible. Stebleton proposes a silicone rubber which is flexible and will bend, although the patent also describes the tubes as having a pre-set curvature. The patent to Cohen contains a general statement that the outer tube can be made of polyethylene which at elevated temperatures can be bent.
GENERAL DESCRIPTION OF THE PRESENT INVENTION The present invention concerns a tracheal tube device and method of making it marked by simplicity and economy of manufacture and convenience in packaging and use. The outer tube is initially cast in straight uncurved Patented Sept. 21, 1971 'ice form of a thermoplastic material which is immediately bent while soft and flexible into the desired radius and upon cooling becomes stiff and rigid with the pre-set radius. This method eliminates intricate and expensive mold construction.
The inner tube is likewise cast as a straighttube but of an elastomeric plastic material and with a thinner wall than the outer tube and in use it may be inserted in the outer tube and readily conforms in shape thereto. Similarly to the outer tube the mold for the inner tube may be of simplified economical construction. The need for insuring that the radius conforms in casting to that of the outer tube, as is the case where both tubes are cast with a pre-set radius, is therefore eliminated. In fact in the present case there is no need for extreme accuracy as to the radius of the outer tube since the inner tube can readily conform thereto and variations in the curvature of the outer tube are of no concern. Also the straight inner tubes simplify the packaging of a number thereof in a container.
Although the prior art contains many proposals or suggestions regarding the use of various plastic materials and various references to flexible tubes and pre-set shapes, no prior disclosure is known of the combination of the steps and features and attendant advantages described above.
Further features and advantages will be made apparent from consideration of a specific embodiment of the article and its method of manufacture and use. Accordingly in connection with the description thereof to follow, reference should be had to the accompanying drawings, in which:
FIG. 1 is a cross sectional view of the outer tube as originally cast or molded;
FIG. 2 is a cross sectional view of the inner tube as molded;
FIG. 3 is an assembly view partly in section showing the outer tube bent into its final normal shape with the inner tube inserted therein;
FIG. 4 is an end view looking from the right in FIG. 3; and
'FIG. 5 is a plan view of an obturator normally employed in connection with the insertion of the tracheal device in the patients throat.
The outer tube 10 includes a flange or plate portion 11 having a pair of slot openings 12 therein for reception of a band adapted to encircle the patients neck for holding the tracheal device in position in the usual manner. The inner tube 15 is provided with a stop means limiting the extent of insertion in the outer tube such a means comprising in the present case an enlarged diameter portion 16 having a shoulder 17 limiting the insertion of the inner tube. The inner tube is provided with an annular flange 18 whereby it may be grasped for ready withdrawal of the inner tube.
The outer tube may be comprised of various materials the essential characteristics being that it is capable of being molded in a straight shape as shown in FIG. 1 and thereafter while heated bent into a curved shape such as that indicated in FIG. 3 and upon cooling being sufficiently rigid and stiff to enable insertion in the throat of a patient and retain its shape. The selected material must of course be inert to human body substances. Various thermoplastic materials are available which are adapted to serve the necessary requirements. Among these are certain polyolefins such as polyethylene or polypropylene. Other materials are polystyrene, nylon, silicone rubbers and various other natural and synthetic rubbers of appropriate grades. Linear polyethylene is particularly well suited for the purpose.
As in the case of the outer tube the inner tube may be composed of various plastic materials but of the clastomeric type and molded in a straight shape capable of being readily inserted in the outer tube while in position in the patients throat and conforming to the shape and curvature of the outer tube and also readily withdrawn for sterilization or usually replacement by a new inner tube. Grades or modified forms of the materials mentioned above for the outer tube can be obtained which will serve. A material particularly well adapted for the inner tube is ethyl vinyl acetate.
The tracheal device may be made in various sizes in accordance with common practice. Preferably the tubes have a slight taper increasing in diameter from the inner end to the outer exposed area. The wall thickness of the outer tube will vary depending particularly on the character of the material employed, the material and wall thickness being selected to provide the required rigidity and stiffness described above. As a specific example with linear polyethylene the wall thickness is preferably in the neighborhood of about .080 of an inch.
As heretofore described, after the outer tube is molded in the straight form shown in FIG. 1 and in broken line in FIG. 3 it is bent on a suitable radius to the curved shape indicated in FIG. 3 which normally would be about 90. The bending is of course performed while the material is hot and conveniently may be done immediately following the casting of the tube, although in some instances depending upon circumstances including the particular material it may be performed after preheating the outer tube. In any event it is essential that the tube have substantial rigidity and stiffness when cooled in the final form particularly against any tendency to collapse.
As heretofore described casting the outer tube in initially a straight form eliminates intricate and expensive mold construction and operations. The casting may of course be performed by injection molding and among other advantages it avoids any fins or ridges on the outer surface of the outer tube such as commonly occurs with split molds. It is of course very desirable that the outer surface be completely smooth for insertion in the patients throat.
The inner tube preferably is tapered, gradually increasing in size from the inner end to the enlarged portion 16 and generally conforming to the inner diameter and taper of the outer tube. However, to insure a close seal the extreme inner end of the outer tube has a decreased inner diameter portion indicated at 22 and the inner end of the inner tube has an outer diameter sufficient to result in a tight squeeze and a fluid seal at the inner end to the enlarged portion 16, although generally accomplished since the inner tube is relatively thin walled and flexible. The remainder of the inner tube 15 from the inner end of the enlarged portion 16, although generally corresponding to the tapered diameter of the outer tube, may be substantially smaller than the inner diameter of the outer tube since a seal is provided at the inner end area 22. The wall thickness of the inner tube, as in the case of the outer tube, may vary dependent upon the material selected. In general it may be relatively thin since it is not subject to any substantial stress. In a specific example employing ethyl vinyl acetate the wall thickness was about .035 of an inch.
The inner tube is readily insertable in the outer tube after the outer tube has been stationed in the patients mouth. Being flexible the inner tube readily follows the curvature of the outer tube and it can be easily withdrawn. Although normally the same tube may be sterilized and reinserted, it is contemplated that it will be discarded and replaced by a fresh sterile tube. This may be economically done since the inner tube is composed of a minimum of material. Being cast in a straight form a number of the inner tubes may be packaged in a single container for distribution.
Commonly the tracheal device is accompanied by an obturator 25 such as that shown in FIG. 5 having a flexible slender stem 26 and an inner bulb portion having a conical forward shape 27 whereby it will extend out the inner end of the outer tube a sufficient distance to form a closed end and seal when the outer tube with the obturator therein is initially inserted in the patients throat. The obturator will of course include a suitable handle portion such as that shown at 28 for ready manual withdrawal and replacement of the obturator with an inner tube 15.
Since various changes in carrying out the method of fabricating the tracheal device and certain modifications in the article may be made without departing from the scope of the invention it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.
1. A method of producing a tracheal device comprised of outer and inner telescopic tubes comprising casting an outer tube initially in straight form of moldable plastic material which is relatively rigid when cool, while heated bending said outer tube into the curved shape suitable for tracheal use, casting the inner tube in straight form of a plastic material which remains flexible when cool and is freely capable of insertion in and withdrawal from the outer curved tube, and inserting said flexible tube into said rigid tube.
2. A method of producing a tracheal device in accordance with claim 1 in which the outer tube is comprised of a thermoplastic material.
3. A method of producing a tracheal device in accordance with claim 2 in which the outer tube is cast from heated thermoplastic material and while still heated and plastic is bent into the curved shape.
4. A method of producing a tracheal device in accordance with claim 1 in which the inner tube is comprised of ethyl vinyl acetate.
References Cited UNITED STATES PATENTS 1,876,744 9/1932 Babb 264295 2,508,347 5/1950 Marsh 29434 3,011,211 12/1961 Barns 2642l0 3,013,308 12/1961 Armour 2945l 3,085,293 4/1963 Kritchever 264-210 2,765,792 10/1956 Nichols 128-351 3,334,631 8/1967 Stebleton 128351 3,419,004 12/1968 Berman 128351X 3,508,554 4/1970 Sheridan 128-348 CHANNING L. PACE, Primary Examiner US. Cl. X.R.
l28-35l; 2642l0, 295, 339