Catheter Guide Wire

Abstract

A catheter guidewire for facilitating introduction of a flexible catheter into the human body (e.g., into the bladder) has a proximal end having a first stiffness which is sufficient to facilitate guidance of a stiff plastic expansion sheath through the tissue. A distal end of the guide wire has a second stiffness, substantially less than the first stiffness, to avoid damage to internal walls of the bladder. Preferably, the guide wire incorporates an intermediate portion having a stiffness between the first stiffness value and the second stiffness value.

1 . A guidewire for introduction into a body via a hollow needle, comprising:
 a proximal end having a stiffness greater than 10 N; and   a distal end having a stiffness less than 3 N,   the stiffness being defined as the force required to produce an angular lateral displacement of 30 degrees when applied at a distance of 10 mm along the respective length of guidewire.   
   
   
       2 . The guidewire of  claim 1  further including an intermediate portion having a stiffness lying between the stiffness of the proximal end and the distal end. 
   
   
       3 . The guidewire of  claim 1  in which the distal end comprises a coil having a central core. 
   
   
       4 . The guidewire of  claim 2  in which the distal end and the intermediate portion comprise a coil having a central core, the core having a first diameter in the intermediate portion greater than a second diameter in the distal portion. 
   
   
       5 . The guidewire of  claim 4  in which the central core has a tapering diameter in the intermediate portion towards the distal end. 
   
   
       6 . The guidewire of  claim 1  in which the distal end extends over a length of between 10 and 15 cm. 
   
   
       7 . The guidewire of  claim 6  in which the distal end extends over a length of 12.5 cm±1 cm. 
   
   
       8 . The guidewire of  claim 2  in which the distal end extends over a length of between 2 and 8 cm, and in which the intermediate portion extends over a length of between 2 and 8 cm. 
   
   
       9 . The guidewire of  claim 8  in which the distal end extends over a length of at least 2 cm and in which the intermediate portion extends over a length of 4 cm±1 cm. 
   
   
       10 . The guidewire of  claim 1  in which the proximal end comprises a hollow tube containing a wire core. 
   
   
       11 . A guidewire for introduction into a body via a hollow needle, comprising:
 a proximal end having a first stiffness;   a distal end having a second stiffness less than said first stiffness; and   an intermediate portion having a stiffness lying between the first and second stiffness values.   
   
   
       12 . The guidewire of  claim 11  in which the distal end comprises a coil having a central core. 
   
   
       13 . The guidewire of  claim 12  in which the distal end and the intermediate portion comprise a coil having a central core, the core having a first diameter in the intermediate portion greater than a second diameter in the distal portion. 
   
   
       14 . The guidewire of  claim 13  in which the central core has a tapering diameter in the intermediate portion towards the distal end. 
   
   
       15 . The guidewire of  claim 11  in which the distal end extends over a length of between 10 and 15 cm. 
   
   
       16 . The guidewire of  claim 15  in which the distal end extends over a length of 12.5 cm±1 cm. 
   
   
       17 . The guidewire of  claim 11  in which the distal end extends over a length of between 2 and 8 cm, and in which the intermediate portion extends over a length of between 2 and 8 cm. 
   
   
       18 . The guidewire of  claim 7  in which the distal end extends over a length of at least 2 cm and in which the intermediate portion extends over a length of 4 cm±1 cm. 
   
   
       19 . The guidewire of  claim 11  in which the proximal end comprises a hollow tube containing a wire core. 
   
   
       20 . The guidewire of  claim 1  in which the proximal end has a stiffness adapted to facilitate the guiding of a substantially rigid catheter sheath of diameter in the range 5 to 7 mm into the bladder via the supra-pubic region of the human body. 
   
   
       21 . The guidewire of  claim 1  forming part of a kit comprising:
 a hollow needle having an inside diameter adapted for receiving the guidewire; and   a catheter sheath having an internal diameter adapted to receive the guidewire and to penetrate the supra-pubic region of the human body using the proximal portion of the guidewire as a guide, the catheter sheath having a peelable outer skin.   
   
   
       22 . A bladder drainage kit comprising:
 a guidewire having an outside diameter less than 2 mm and having a proximal end having a first stiffness and a distal end having a second stiffness, the second stiffness being less than the first stiffness;   a peelable catheter sheath adapted to receive the guidewire and to penetrate the supra-pubic region of the human body using the proximal portion of the guidewire as a guide, the catheter sheath having an inside diameter at its distal end approximately equal to the outside diameter of the guidewire, and an inside diameter at its proximal end of at least 4 mm for receiving a flexible drainage catheter.   
   
   
       23 . The kit of  claim 22  in which the peelable catheter sheath further includes an inner sheath for stiffening the peelable catheter sheath during insertion into the body, the inner sheath being withdrawable from the proximal end of the peelable catheter sheath. 
   
   
       24 . The kit of  claim 22  in which the guidewire has a diameter at its distal end in the range 750 to 1000 microns. 
   
   
       25 . A method for introducing a catheter into the bladder of the human body in the supra-pubic region comprising the steps of:
 introducing a needle into the bladder via the supra-pubic region, the needle having an outside diameter less than 2 mm;   inserting a guidewire having an outside diameter less than 2 mm into the bladder through an internal bore of the needle;   withdrawing the needle over the guidewire;   introducing a peelable catheter sheath into the bladder over the guidewire, the catheter sheath having a distal end of outside diameter less than approximately 2 mm and a proximal end having an outside diameter of at least 4 mm;   withdrawing the guidewire through the catheter sheath;   inserting a flexible catheter into the bladder through the catheter sheath; and   peeling away the catheter sheath from the flexible catheter leaving the flexible catheter in situ.   
   
   
       26 . (canceled)