Flexible, kink-resistant catheter
First Claim
1. A catheter for insertion into biological tissue, comprising:
- a tubular sheath having a longitudinal passageway therein capable of transporting a fluid to said tissue and a minimum predetermined strength capable of maintaining a predetermined flow rate of said fluid within said passageway when said sheath is flexed; and
an elongated coil having a first plurality of closely-coupled turns and expansion friction-fitted and longitudinally movable within said longitudinal passageway of said tubular sheath, said coil distributing radial and longitudinal forces over said sheath without rupturing said sheath when said sheath is flexed.
1 Assignment
0 Petitions
Accused Products
Abstract
An extremely small diameter epidural catheter is disclosed which is both flexible and kink-resistant when flexed. The catheter includes a tubular sheath or tube having a passageway therein for the delivery of fluids to biological tissue. Positioned in the passageway is a coil which is expansion-fitted therein to form a composite wall structure which is extremely flexible and kink-resistant. This composite wall structure is utilized to form a catheter having an extremely small outside diameter in a range of 0.010" to 0.032" for delivering acceptable levels of fluid volume. The coil comprises a plurality of closely spaced turns extending from the proximal to almost the distal end thereof. About the distal end of the coil is a number of loosely coupled or relaxed turns which adds further flexibility to the distal end of the catheter. The tubular sheath of the catheter comprises a high tensile or flexural strength material which does not rupture or tear when the catheter is bent or flexed. Maintaining the ratio of the outside diameter of the wire coil to the cross-sectional diameter of the individual turns within a range of 4 to 10 prevents the tubular sheath from either rupturing or kinking when the catheter is flexed or bent.
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Citations
20 Claims
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1. A catheter for insertion into biological tissue, comprising:
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a tubular sheath having a longitudinal passageway therein capable of transporting a fluid to said tissue and a minimum predetermined strength capable of maintaining a predetermined flow rate of said fluid within said passageway when said sheath is flexed; and an elongated coil having a first plurality of closely-coupled turns and expansion friction-fitted and longitudinally movable within said longitudinal passageway of said tubular sheath, said coil distributing radial and longitudinal forces over said sheath without rupturing said sheath when said sheath is flexed. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A flexible, kink-resistant catheter for insertion into biological tissue, comprising:
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a tube including a material of a minimum predetermined strength and having a longitudinal passageway therein capable of transporting a fluid to said tissue said tube having an outside diameter less than said 0.33" and a wall thickness in a range of 0.001" to 0.003"; and a spiral coil expansion friction-fitted and longitudinally movable within said passageway and having a circumference in contact with an inside surface of said tube, said coil distributing radial and longitudinal forces over said sheath without rupturing said sheath when said sheath is flexed. - View Dependent Claims (16, 17, 18, 19)
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20. An epidural catheter for insertion into biological tissue, comprising:
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a tubular sheath having a longitudinal passageway therein capable of transporting a fluid to said tissue and comprising a polyimide material having a nominal flexural strength of at least 20,000 pounds per square inch, said sheath having an outside diameter in a range of 0.010" to 0.032" and a wall thickness in a range of 0.001" to 0.003"; and a spiral coil of stainless steel wire friction-fitted within said longitudinal passageway of said sheath, said coil having an outside diameter in a range of 0.001" to 0.026", said wire having a diameter in a range of 0.001" to 0.003", said sheath and said coil forming a wall structure having a thickness in a range of 0.002" to 0.006", said outside diameter of said coil to said diameter of said wire forming a ratio in a range of 4 to 10, said coil having a first plurality of turns and a second plurality of turns about the distal end thereof and more loosely coupled than said first plurality of turns.
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Specification