Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Patent
1996-01-30
1998-12-29
Stemmer, Daniel
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
156278, 1563042, 427 23, 604265, 604280, A61M 2516
Patent
active
058535187
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a process for manufacturing a catheter, for instance of the type used for insertion into the urethra, said catheter preferably being coated by a layer of a hydrophilic material, said catheter further being provided with a drainage or flushing opening adjacent to the free end which is to be inserted into the urethra.
BACKGROUND TO THE INVENTION
Hydrophilic coated catheters are known, for example, from U.S. Pat. No. 4,585,666 and U.S. Pat. No. 4,666,437 (Lambert/Astra Meditec AB) or U.S. Pat. No. 4,906,237 (Johansson et al./Astra Meditec AB).
U.S. Pat. No. 4,773,901 (Norton/C. R. Bard, Inc.) discloses a catheter with a selectively rigidified tip portion. The tip is coated with a hydrophilic polymer which absorbs or adsorbs water in use so as to render the tip soft.
A commonly used technique when manufacturing catheters of the above kind is to use an extruded flexible tube made of polymer material such as PVC or polyethylene or a similar material and which has appropriate dimensions as a starting material. The end of the tube is welded or melted shut or otherwise closed at one end. If so desired, the outside of the catheter is then provided with a hydrophilic layer. The drainage/flushing hole is then punched into the tube.
A first way of performing the punching operation may be by means of a glancing movement relative to the tube in which a part-circular part of the sidewalls of the tube is cut away by means of the punch. A disadvantage with this punching operation is the difficulty to obtain an exact size of the hole, since a small error in the alignment of the punch or in the tubing dimension will result in a great difference in the size of the punched hole. This difficulty in obtaining an exact size of the hole may be remedied by using a second way of performing the punching operation. In this second operation the punch is centred over the tube and lowered on to the tube, compressing the sidewalls of the tube onto each other and punching through the uppermost sidewall, and stopping the punching operation well before there is any risk of penetrating the lower sidewall. The hole resulting from this punching operation will always be of the same size. The difficulties connected with this operation is to decide exactly when to stop the punch so as to be sure that one sidewall has been fully penetrated but the other sidewall with certainty has not been penetrated. It may be easier to adjust the punch exactly when holes are punched in uncoated standard tubes having well-defined wall thicknesses, but it may be different when the tube has been coated with a layer, for instance a hydrophilic layer, since the layer affects the dimensions of the tubing, at least to some extent.
Another problem in the manufacture of coated catheters arises when a catheter made from a standard tube is formed with a curved tip (for instance a so called Tiemann-catheter), since the heat treatment connected with the coating procedure or with a subsequent sterilisation may result in that the tip straightens again due to the "memory" of or to the remaining, unrelieved tensions in the polymer in the tube. The "memory" of the material may be defined as the tendency of the material to resume its original shape due to the inherent orientation of the material.
DISCLOSURE OF THE INVENTION
In accordance with the invention the above difficulties are resolved in that the tip portion of the catheter, including an inner lumen and a drainage/flushing hole is injection moulded with inner and outer diameters corresponding to those of a standard tube and subsequently joined to said standard tube.
Thus, according to the present invention there is provided a process for manufacturing a catheter for insertion into a body cavity, for instance of the type used for insertion into the urethra, said catheter having a tip portion provided with one or several drainage or flushing openings adjacent to the free end which is to be inserted into said body cavity, the outside of the catheter being p
REFERENCES:
patent: 3566874 (1971-03-01), Shepherd
patent: 4188954 (1980-02-01), Patel et al.
patent: 4585666 (1986-04-01), Lambert
patent: 4666437 (1987-05-01), Lambert
patent: 4773901 (1988-09-01), Norton
patent: 4863442 (1989-09-01), DeMello
patent: 4898591 (1990-02-01), Jang
patent: 4906237 (1990-03-01), Johansson et al.
patent: 5217493 (1993-06-01), Raad
Astra Aktiebolag
Stemmer Daniel
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