Method for forming and sterilizing catheters

Abstract

A catheter for insertion into the human body and made of a thermoplastic tubing, is preformed to a desired shape by heating it above its free form temperature and allowing it to cool while held in that shape. To hold the catheter in position for such forming .Iadd.and/or for storage before use.Iaddend., a forming board having a catheter receiving groove of the desired shape is used. .[.The.]. .Iadd.In the form of the invention shown, the cross-sectional shape of this groove is wider at the bottom and narrower at the open top where it becomes a part of the board so as to hold the catheter in place during the forming and storage and to allow the catheter to be easily removed thereafter. This .Iadd.particular form of .Iaddend.forming board is made by vacuum forming a sheet of thermosetting plastic .Iadd.or thermoplastic material .Iaddend.over a solid, non-heat responsive, master representation of the exact longitudinal shape of the final preformed catheter. The cross-sectional shape of the master is the negative of the desired cross-section of the final forming board groove. When the catheter has been .[.so.]. preformed .Iadd.and lies in one of the forming board grooves, .Iaddend.it and its forming board are packaged in a sealed plastic bag which is, like the catheter and the forming board, permeable to sterilizing gas. The resulting package is gas claved and stored in this sealed condition until ready for use. The catheter is removed from the sealed package and .Iadd.from .Iaddend.the forming board immediately before insertion into the body. When it has served its purpose, it .[.is.]. .Iadd.can be .Iaddend.removed from the body, cleaned, positioned back into .[.the.]. .Iadd.a .Iaddend.forming board, preformed with heat when necessary, placed in another sealed film container, and resterilized for storage until it is again needed.

I claim:  .[.1. A method of forming into a predetermined shape an elongated strip of thermoplastic material having a temperature above which it is free forming and below which it tends to retain its shape, the method including the steps of: 
     
        form temperature..]. 2. A method of making and preserving in readiness for use a catheter for use within the human body, .Iadd.said catheter comprising an elongated strip of thermoplastic material having a temperature above which it is free forming and below which it tends to retain its shape, the method .Iaddend.including the steps .[.enumerated in claim 1, followed by the following steps.]. .Iadd.of.Iaddend. : .Iadd. 1. preparing a forming board having a groove of shape to support a catheter in a predetermined desired configuration;   2. supporting the catheter in said groove to constitute a forming board-catheter unit;   3. heating this unit at least to the free form temperature of the catheter material;   4. reducing the temperature of the unit to substantially below the free form temperature; .Iaddend.   5. encompassing the forming board-elongated strip unit in a hermetically sealed envelope;   6. sterilizing the interior of the envelope and the contents thereof; and   7. retaining the catheter in the forming board and in the envelope until it   
     
     
        is ready to be used. 3. The method of claim 2 wherein the steps of supporting the catheter in the groove consists of constituting the groove as of pear-shaped configuration in cross section, the groove opening to the surface of the forming board, and having a top surface dimension less than that of the normal diameter of the catheter, and having a larger, 
     
     
        lower, dimension sufficient to encompass the catheter. 4. The method of claim 2 wherein the forming board has been prepared to have a groove of shape to support a catheter by preparing a master having such predetermined desired configuration, setting this master on an air permeable base, heating a sheet of thermosetting plastic, and drawing it down on the master and the base by vacuum forming methods, allowing it to cool and removing it from the base and the master from it. .Iadd. 5. A method of preparing and preserving in readiness for use a catheter for use within the human body, said catheter comprising an elongated strip of thermoplastic material having a temperature above which it is free forming and below which it tends to retain its shape, the method including the steps of: 1. preparing a forming board having a groove of shape to support a catheter in a predetermined desired configuration;   
     
     
       2.  supporting a catheter in said predetermined desired configuration; 3. heating the catheter at least to the free form temperature of the catheter materials;   4. reducing the temperature of the catheter to substantially below the free form temperature;   5. supporting the catheter in said groove of said forming board to constitute a forming board catheter unit;   6. encompassing the forming board-elongated catheter unit in a hermetically sealed envelope;   7. sterilizing the interior of the envelope and the contents thereof; and   8. retaining the catheter in the forming board and in the envelope until it is ready to be used. .Iaddend. .Iadd. 6. The method of claim 5 wherein the forming board has been prepared to have a groove of shape to support a catheter by preparing a master having such predetermined desired configuration, setting this master on an air permeable base, heating a sheet of thermosetting plastic, and drawing it down on the master and the base by vacuum forming methods, allowing it to cool and removing it from the base and the master from it. .Iaddend..Iadd. 7. The method of claim 5 wherein the steps of supporting the catheter in the groove of the forming board consists of constituting at least part of the groove as of pear-shaped configuration in cross-section, the groove opening to the surface of the forming board, and having a top surface dimension less than that of the normal diameter of the catheter, and having a larger, lower, dimension sufficient to encompass the catheter. .Iaddend.