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United States Patent  [ii] Patent Number: 4,698,059
Johnson  Date of Patent: Oct. 6, 1987
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Primary Examiner—C. Fred Rosenbaum
Assistant Examiner—Sherri E. Vinyard
Attorney, Agent, or Firm—Sherman & Shalloway
An enteral feeding tube includes a unitary, molded weighted bolus insert molded to a preformed tubular stem. The bolus and stem are each formed from a polymeric composition including a thermoplastic elastomeric block copolymer, e.g. styrene-ethylene-butylenestyrene, and an essentially linear polysiloxane having a kinematic viscosity at room temperature of 20 to 106 centistokes, and optionally, polypropylene and/or mineral oil. The bolus is weighted with tungsten powder mixed into the polymeric composition. The bolus includes a central bore extending over at least a portion of its length and communicating with the interior of the stem and to the exterior of the bolus.
27 Claims, 6 Drawing Figures
U. S. Patent Oct 6,1987 Sheet 2 of2 4,698,059
ENTERAL FEEDING TUBES
This application is a continuation, of application Ser. No. 559,685, filed Dec. 9, 1983 now abandoned. 5
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to enteral feeding tubes. More specifically, this invention relates to enteral feed- 10 ing tubes formed of a polymeric composition comprising a block copolymer and a polysiloxane, and a unique weighted bolus for use therewith.
2. Description of the Prior Art
Enteral feeding (stomach and intestinal feeding) is 15 commonly used to nourish patients who, for a variety of reasons, cannot consume food normally. Compared with intravenous (parenteral) feeding, enteral feeding is a more natural way to supply the patient with nutrition while helping to reduce possible infection and vein 20 damage.
Conventional enteral feeding tubes are made of polyvinylchloride, elastomeric silicone or polyurethane. These materials have been found to be unsatisfactory for the following reasons. For polyvinylchloride, stom- 25 ach acids can leach out the plasticizer from the polyvinylchloride. If the tube is left in the stomach for an extended period of time, the leached tube hardens and becomes brittle and distorted. As is apparent, this causes patient discomfort and can make removal of the tube 30 difficult and painful. On the other hand, elastomeric silicone tubing is much softer and resists hardening. However, because of its limpness, an elastomeric silicone tubing is extremely difficult to insert and position in the stomach. Although polyurethane tubes have in- 35 termediate flexibility and are easier to insert than silicone, they are still difficult to insert and position.
In general, an enteral feeding tube comprises an elongated stem (tube body) having two ends—a distal end which ultimately is positioned within the stomach or 40 intestines of a patient and a proximal end which remains out of the patient and preferably is equipped with a connector for attachment to a nutritional support system. The distal end may be joined to a weighted terminal (bolus) and the proximal end may have a female 45 connector with an integrally formed closure plug. The connector and bolus usually are connected to the stem by bonding agents or adhesives. As a result of the use of these bonding agents, a secure bond may not be achieved and additional foreign substances are intro- 50 duced into the body of the patient.
The weighted bolus normally comprises a pouch containing therein a heavy material. Mercury has been most often used as the weighted material. However, inasmuch as mercury is a highly toxic material and can 55 cause much harm to the patient should the pouch burst, a substitute therefor should be used.
In order to administer nutrients to the patient through the enteral feeding tubes, current tubes have openings formed in the wall of the tube body proximally of the 60 weighted bolus. These openings create weakened areas in the tube body which may cause the tubes to kink and, thus, to occlude the tube and obstruct the flow of nutrient. Because of the use of mercury or other such materials in the bolus, it heretofore has been impossible or 65 impractical to provide the openings in the bolus itself where the likelihood of kinking would be greatly reduced or totally eliminated.
Thus there is a need for an enteral feeding tube formed of a material which is easy to handle because of the desired degree of flexibility, can withstand the action of stomach acid and have a smooth surface which will not irritate the patient's tissues. Moreover, there is a need to eliminate the hazards associated with the use of mercury and other unbonded substances in the weighted bolus and also to eliminate or greatly reduce the possibility of kinking and its associated problems. The present invention was made with the objective of overcoming the known shortcomings of conventional enteral feeding tubes.
SUMMARY OF THE INVENTION
The present invention provides an enteral feeding tube formed of a polymeric composition comprising a thermoplastic elastomeric hydrocarbon block copolymer and a polysiloxane. The block copolymer comprises blocks of styrene-ethylene-butylene-styrene wherein the styrene blocks have a molecular weight of 5,000 to 40,000 and the ethylene-butylene block, 20,000 to 500,000. The polysiloxane has a kinematic viscosity of 20 to 106 centistokes at room temperature.
In one embodiment of the invention, the distal end of the enteral feeding tube is provided with a weighted bolus formed from a unique formulation of a polymeric composition and tungsten. The tungsten is a heavy material that, when compounded with the polymeric composition, may be molded into a variety of configurations and, preferably, it may be insert molded directly onto the distal end of the tube body. This eliminates the necessity of using bonding agents to secure the bolus to the tube.
Also, the unique compounded bolus formulation may be molded or otherwise formed into a hollow configuration which permits the formation of openings directly in the bolus, thus, avoiding the requirement of having the openings in the tube body where kinking may occur.
As a further advantage of the present invention, because of the compatibility of materials utilized in the construction of the tubing stem and the connector, these components also may be firmly secured together during the insert molding of the connector directly onto the proximal end of the tubing without the use of bonding agents.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows an extruder screw useful in forming the present enteral feeding tube.
FIG. la shows the flights in the material and feed sections of the screw of FIG. 1.
FIG. 2 illustrates the enteral feeding tube of this invention wherein openings are provided in the weighted bolus.
• FIG. 3 shows in detail the distal end of the enteral feeding tube of FIG. 2.
FIG. 4 illustrates the distal end of the present enteral feeding tube wherein an opening is provided at the distal end of the weighted bolus.
FIG. 5 shows the distal end of the present enteral feeding tube having no weighted bolus.
DETAILED DESCRIPTION OF THE
The present invention provides enteral feeding tubings formed of a composition comprising a substantially uniform mixture of an elastomeric thermoplastic hydrocarbon block copolymer and a polysiloxane. The com