Endoscopic needle

Details Endoscopic needle Endoscopic needle

2000-03-07

2004-06-01

Bennett, Henry (Department: 3743)

Surgery

Means for introducing or removing material from body for...

Treating material introduced into or removed from body...

Reexamination Certificate

active

06743206

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates broadly to surgical instruments. More particularly, this invention relates to endoscopic instruments, and particularly endoscopic needles.
2. State of the Art
Endoscopic needle assemblies are used with flexible endoscopes to inject fluids under endoscopic visualization in body structures such as the esophagus, the colon, and the stomach. For example, when removing polyps from within the colon, it is customary to inject saline solution into the tissue surrounding and underlying a polyp in order to “raise” the polyp thereby facilitating excision by means of forceps or snares. Visible dyes and radiological contrast dyes are sometimes injected to mark the location of areas explored endoscopically so that the structures can be located during subsequent procedures. Also, sclerosing agents are sometimes injected into vascular structures, such as esophageal varicoceles, in order to cause clotting and to necrose the tissue so that it can be reabsorbed by the body.
Such needle assemblies generally consist of a needle, an inner flexible tube, a flexible outer tube, a handle assembly and an injection syringe. The inner flexible tube provides a fluid pathway, and is surrounded by the loose-fitting flexible outer tube. The needle is connected to the distal end of the inner tube by use of adhesives, a stainless steel crimp band, or both, and the handle assembly is connected to the proximal end of the inner tube. Attached to the handle is an injection syringe, which supplies fluid to the fluid pathway of the inner tube when a plunger of the syringe is pushed. The inner tube is designed for the dual purpose of conducting fluids injected by a syringe located at the handle to the tissue surrounding the needle and for imparting motion produced at the handle to the needle. The handle assembly permits the user to move the inner tube in and out relative to the outer tube, thus retracting the needle into the outer tube or extending it beyond the distal tip of the outer tube. The outer tube is generally formed from a relatively flexible plastic polymer material such as PTFE or FEP. Sometimes the outer tube is also fitted with a band of stainless steel to reinforce its distal tip. The inner tube is generally formed from PTFE.
The needle assembly is designed to be inserted and fed into a smooth cylindrical working channel of an endoscope. In order to make the needle assembly flexible enough to negotiate the curves of an endoscope during use and to allow free motion of the needle assembly within the working channel of the endoscope, it is desirable to make the outer tube and the inner tube from a relatively flexible plastic polymer material such as PTFE or FEP. When the needle assembly is positioned properly within the endoscope, the needle of the needle assembly can be extended through a distal port in the endoscope by application of force on the handle of the needle assembly. When the operator applies the actuating force to the handle to extend the needle, a compressive force is applied to the inner tube, and a reactive tensile force is applied to the outer tube. Typically, the plastic inner tube is compressed and shortened and the plastic outer tube is stretched and elongated. This distortion causes the relative motion of the needle and the distal end of the outer tube to be sluggish and less than the full motion imparted to the handle on the proximal end of the device. Further, because of friction between the inner tube and outer tube, the motion of the needle relative to the distal tip of the outer tube is not immediate and direct; i.e., the force is not immediately and directly applied to the endoscopic needle assembly because the flexible polymer materials of the inner tube and the outer tube have some degree of elasticity in compression and tension and the force applied by the actuating handle is initially absorbed by the plastic material itself before it is translated into a positive and certain motion of the distal end of the endoscopic needle assembly.
Several problems result from the poor transmission of translational motion from handle to needle. First, the user must be able to move the endoscopic needle assembly relative to the endoscope's working channel (a lumen adapted to receive endoscopic instruments therethrough) in order to position the needle relative to the end of the endoscope and to stick the needle into the desired tissue. The compressiveness of the standard plastic outer tube and its friction relative to the endoscope's working channel and against the inner tube works against the ability of the user to precisely move the assembly in and out of the working channel. Second, it is difficult or impossible to push the needle into the tissue where an injection is desired by means of relative motion of the needle and the outer tube. Hence, the outer tube must be moved relative to the endoscope or the endoscope must be moved within the patient to effect the desired injection. Third, since the motion of the needle relative to the distal tip of the outer tube is not positive and certain, it is possible for the needle to move to an extended position when such is not desired. For example, it is possible for the needle to advance beyond the distal tip of the outer tube while the needle assembly is still within the working channel of the endoscope, which can result in internal damage to the endoscope and to the needle itself.
U.S. Pat. No. 5,601,588 to Tonomura et al. shows an endoscopic needle assembly in which the inner tube is made of metal, e.g., stainless steel or a super-elastic alloy, in order to minimize the compression in the inner tube. The needle may be formed integrally with the metallic inner tube or made as a separate part and attached to it. While the Tonomura et al. device offers an improvement to the standard all plastic construction, it also has several disadvantages. First, the stainless steel inner tube is stiffer than desired. The inner tube can be kinked if bent too tightly, and will take a permanent set if flexed beyond its elastic limit, as might be the case when the endoscope is tightly flexed while negotiating a tortuous colon or when being retroflexed. Second, a super-elastic alloy tube construction is prohibitively expensive for the intended general endoscopic use. Third, Tonomura et al. specifically does not address several problems: (1) accidental exposure of the needle within the endoscope, (2) the need for improving the tensile stiffness of the outer tube, and (3) the need for reducing the friction of the outer tube within the working channel of the endoscope to improve the user's control of the endoscopic needle relative to the endoscope.
Other prior art exists relating to endoscopic needle devices, but none of the prior art teaches improvements in the relative motion of the inner tube and outer tube, nor in flexibility and kink resistance of the inner tube, nor in reducing friction between the outer tube and the working channel of the endoscope.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide an endoscopic needle assembly with an improved inner tube with reduced compression and reduced likelihood of kinking resulting in better control of the needle from the endoscope handle.
It is another object of the invention to provide an endoscopic needle assembly having an outer tube with improved tensile stiffness, i.e., a relatively small amount of longitudinal stretching or compression caused by a given amount of tensile or compressive force, resulting in more direct control of the needle within the endoscope.
It is a further object of the invention to provide an improved endoscopic needle assembly with a safety shield by which accidental exposure of the needle within the endoscope is prevented.
It is an additional object of the invention to provide an endoscopic needle assembly with an improved outer tube having a friction reducing exterior surface such that friction is reduced between the outer tube and the working channel of the endoscope to

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