Patent Application
20180001054
The disclosure relates generally to medical instruments such as catheter and endoscopic systems, and more particularly to reducing backlash in such instruments.
Medical instruments such as catheters, endoscopic instruments, and, endoscopic and catheter systems are usually constructed of long tubular or tubular-like main bodies connecting opposite ends of devices useful for carrying out medical procedures. Endoscopes can include an insertion tube, defining one or more lumens therethrough where at least one of which is a working channel that receives an endoscopic instrument for procedural purposes. Endoscopes incorporate optical or electronic imaging systems for the transmission of images from bodily cavities for the visualization of the tissue. Endoscopes or parts thereof can be rigid or flexible. Working channels can be located on the outside or inside of the insertion tube of an endoscope. Some of today's sophisticated catheters can resemble endoscopes without the imaging system.
The proximal ends of catheters and endoscopic instruments are typically associated with some actuating means and the distal ends are typically associated with end effectors configured to deliver a desired action to a treatment site. Some endoscopic and catheter systems incorporate an outer tubular member and an inner member insertable therethrough. The mechanical actuation of the end effectors is usually achieved by a relative longitudinal movement between the outer tubular member and the inner member via the action of the actuating means. Actuation can comprise pushing and/or pulling of one of the tubular member and inner member relative to the other to permit, for example, the opening and closing of forceps. Alternatively, a biopsy or other needle coupled to the inner member may be inserted into tissue of a patient by movement of the inner member relative to the outer tubular member.
In such instruments, an outside diameter of the inner member may be smaller than an inside diameter of the tubular member to provide an annular space between the inner member and the tubular member to permit passage of fluid during irrigation or suctioning of the treatment site. The space provided between the inner member and the tubular member can be a cause backlash (i.e., lost motion) experienced by the operator when relative movement between the inner member and the tubular member is carried out to operate the instrument. The amount of backlash can be significant depending on the length and configuration of the instrument and whether the instrument is bent to accommodate the anatomy of the patient during a procedure.
Improvement is therefore desirable.
In one aspect, the disclosure describes a medical instrument comprising:
a first elongate member having an inside surface defining a first lumen having a first center line; and
a second elongate member extending in the first lumen and having an outside surface cooperating with the inside surface of the first member to define a first intermediate longitudinal passage therebetween extending in the first lumen, the second member having a second center line;
wherein the first member and the second member are permanently formed to have non-parallel portions between the first center line and the second center line and define one or more predisposed contact locations between the inside surface of the first member and the outside surface of the second member to reduce backlash during relative longitudinal movement between the first member and the second member.
In another aspect, the disclosure describes a medical instrument comprising:
a first member having an inside surface defining a first lumen; and
a second member extending in the first lumen and having an outside surface cooperating with the inner surface of the first member to define an intermediate longitudinal passage therebetween extending in the first lumen;
wherein one of the inside surface of the first member and the outside surface of the second member is permanently formed to have a sinuous shape defining one or more predisposed locations for contacting the other one of the inner surface of the first member and the outer surface of the second member to reduce backlash during relative longitudinal movement between the first member and the second member.
In a further aspect, the disclosure describes a medical instrument comprising:
a first member having an inside surface defining a first lumen having a first center line, the inside surface being defined by a first cross-sectional profile swept along the first center line; and
a second member extending in the first lumen and having an outside surface cooperating with the inner surface of the first member to define a first intermediate longitudinal passage therebetween extending in the first lumen, the second member having a second center line, the outside surface of the second member being defined by a second cross-sectional profile swept along the second center line;
wherein one of the first member and the second member is permanently formed to have to have a sinuous respective first center line or second center line and define one or more predisposed locations for contacting the other one of the inside surface of the first member and the outer surface of the second member to reduce backlash during relative longitudinal movement between the first member and the second member.
Further details of these and other aspects of the subject matter of this application will be apparent from the detailed description and drawings included below.
Reference is now made to the accompanying drawings, in which:
The present disclosure relates to medical instruments such as catheter and endoscopic systems that exhibit reduced backlash during their operation. In various embodiments, the reduction of backlash avoids the use of protrusions or fins hat can significantly obstruct fluid flow through working channels of the instruments. Aspects of various embodiments are described through reference to the drawings.
Medical instrument 100 may comprise second (e.g., inner) elongate member 14 (e.g. endoscopic instrument) extending substantially longitudinally in lumen 12 and having outside surface 14B. Second member 14 may extend entirely or only partially in lumen 12. Second member 14 may be longitudinally movable relative to first member 10 during operation of medical instrument 10. Alternatively, first member 10 may be longitudinally movable relative to second member 14 during operation of medical instrument 100. The relative movement between first member 10 and second member 14 may serve to actuate an end effector that may be connected to or that may be part of medical instrument 100.
Second member 14 may have center line 14C. Second member 14 may have a tubular (e.g., hollow cross-section) or solid configuration. For example, second member 14 may comprise a guide wire or other endoscopic instrument that may be pushed or pulled relative to first member 10. In various embodiments, second member 14 may be constructed of multiple strands, have a lubricious coating thereon, have an insulating coating thereon, have a core and cladding construction, have different outer diameters and/or be tapered. Second member 14 may have a substantially uniform (e.g., outer) cross-sectional profile along center line 14C where the cross-sectional profile is substantially perpendicular to second center line 14C. Alternatively, second member 14 may have a non-uniform cross-sectional profile along center line 14C. The cross-sectional profile of second member 14 may be substantially circular and smooth or may be of other suitable shape. For example, outside surface 14B of second member 14 may itself be defined by a cross-sectional profile having been swept along center line 14C. A substantially circular cross-sectional profile of second member 14 may be advantageous in some cases to facilitate a sealed connection between second member 14 and some other fluid conduit(s) or device(s) as listed above that may be required during use.
Second member 14 may have a smaller outer cross-sectional dimension (e.g., diameter) than the cross-sectional dimension (e.g., diameter) of lumen 12. Accordingly, outside surface 14B of second member 14 may cooperate with inside surface 10A of first member 10 to define an intermediate longitudinal passage 16 therebetween extending longitudinally in lumen 12. Passage 16 may be configured to permit the passage of fluid though lumen 12 during irrigation or suction of a treatment site for example.
The dimensions of catheters, endoscopic devices and systems are typically determined and limited based on the human anatomy or the animal anatomy in veterinary procedures. For example, inside diameters of microcatheters for neurological use can be as small as 0.017″ (0.43 mm) in diameter and vascular catheters may have inside diameters as small as 0.021″ (0.53 mm). Guide wires (e.g., second member 14) that are used with microcatheters may be as small as 0.014″ (0.36 mm) in diameter. Inside diameters of working channels (e.g., lumen 12) of flexible endoscopes (e.g., first member 10) typically vary from 2 to 4.2 mm and the outside diameters of endoscopic instruments (e.g., second member 14), such as snares, guide wires, endoscopic retrograde cholangiopancreatography (ERCP) devices are limited by the inside diameters of the working channels (e.g., lumen 12) of flexible endoscopes.
In various embodiments, first member 10 and second member 14 may be permanently formed to have non-parallel portions between center line 12C of lumen 12 and center line 14C of second member 14. The non-parallel potions may define one or more predisposed contact locations 18 between inside surface 10 of first member 10 and outside surface 14B of second member 14. For example, such non-parallel portions may include adjacent portions of center line 12C and center line 14C of differing slopes. The non-parallel portions between center line 12C and center line 14C may cause inside surface 10A and outside surface 14B to also have non-parallel portions. Predisposed contact locations 18 may contribute toward reducing backlash during relative longitudinal movement between first member 10 and the second member 14.
Depending on the specific configuration and state of medical instrument 100, outside surface 14B of second member 14 and inside surface 10A of first member 10 may not always be in contact with each other at predisposed contact locations 18. For example, predisposed contact locations 18 may provide locations of closer proximity between outside surface 14B of second member 14 and inside surface 10A of first member 10 so that during relative movement, contact between outside surface 14B and inside surface 10A would more likely be established at predisposed contact locations 18 so as to provide support between first member 10 and second member 14. Depending on the configuration of medical instrument 100 and on the type of actuation taking place between first member 10 and second member 14, the presence of predisposed contact locations 18 may require less relative movement (i.e., backlash) for first member 10 and second member 14 to position themselves relative to each other in a position suitable for transferring an actuation force along either first member 10 or second member 14.
As mentioned above, first member 10 and/or second member 14 may comprise a substantially rigid or, alternatively, a flexible material permitting medical instrument 100 to resiliently bend to accommodate the anatomy of a patient. For example, in some embodiments, first member 10 and second member 14 may be deformed to follow a tortuous path during normal use. Accordingly, such flexible material may permit first member 10 and second member 14 to conform to such tortuous path without exhibiting significant plastic deformation. However, whether or not the material(s) used for first member 10 and second member 14 is/are considered flexible or rigid, predisposed contact locations 18 are intended to be permanently formed by first member 10 and/or second member 14 so as to remain defined during normal use of medical instrument 10. For example, predisposed contact locations 18 are intended to remain at least partially permanently defined even though first member 10 and second member 14 may be non-permanently (e.g., elastically, resiliently) bent to follow a tortuous path. Accordingly, permanent predisposed contact locations 18 may be able to at least partially withstand temporary (i.e., elastic, resilient) deformation that first member 10 and/or second member 14 may be designed to undergo during normal use.
Predisposed contact locations 18 are intended to provide locations of mutual support between first member 10 and/or second member 14 during relative longitudinal movement therebetween and during normal use of medical instrument 100. Accordingly, there may not necessarily be contact at predisposed contact locations 18 when medical instrument 100 is at rest. For example, first member 10 and/or second member 14 may be permanently formed so that there is no contact at some or all of predisposed contact locations 18 and that a clearance is instead provided between first member 10 and second member 14 at predisposed contact locations 18 when medical instrument 100 is at rest. Alternatively, first member 10 and/or second member 14 may be permanently formed so that there is contact at some or all of predisposed contact locations 18 between first member 10 and second member 14 when medical instrument 100 is at rest. Furthermore, in some embodiments, first member 10 and/or second member 14 may be permanently formed so that there is an interference (i.e., friction) fit between first member 10 and second member 14 so as to produce a biasing force between first member 10 and second member 14 at predisposed contact locations 18 when medical instrument 100 is at rest.
First member 10 and/or second member 14 may undergo longitudinal pushing and/or pulling forces to cause relative movement between first member 10 and second member 14 and it is understood that such forces may cause some non-permanent deformation (e.g., compression, elongation, bending, torsion) of first member 10 and/or second member 14 during normal operation of medical instrument 100. However, predisposed contact locations 18 defined via permanent forming of first member 10 and/or second member 14 are intended to at least partially withstand such non-permanent deformation that may be experienced by first member 10 and/or second member 14 during normal use.
As shown in
As shown in the subsequent embodiments, predisposed contact locations 18 could instead be defined by way of at least part of center line 12C having a sinuous shape instead of or in addition to center line 14C. The term “sinuous” as used herein is intended to encompass shapes that include curves, bends and turns and also combinations of straight lines with curves, bends, turns. For example, such sinuous shapes could include one or more of wavy, sinusoidal, helical, saw-tooth, square wave, winding, corrugated and undulated shapes. Even though the longitudinal waviness of some of the components shown herein is represented by a sine wave, the waviness may be of other type(s) such as rectangular, triangular, trapezoid, semi-circular, semi-ellipsoid, or combination(s) thereof. Also the waviness in the components shown herein may be periodic, non-periodic, planar and/or multi-planar.
Accordingly, part of center line 14C and/or part of center line 12C may have one or more sinuous portions. Such sinuous portions may in some embodiments consequently cause outside surface 14B of second member 14 and/or inside surface 10A of first member 10 to have one or more sinuous portions in order to define predisposed contact portions 18. With respect to the embodiment of
The shape(s) of inside surface 10A of first member 10 and/or of outside surface 14B of second member 14 may be configured to provide a plurality of predisposed contact locations 18 that are interspaced along lumen 12. For example predisposed contact locations 18 may be separated by regions that are free of such predisposed contact locations 18. The spacing between predisposed contact locations 18 as well as the size and number of predisposed contact locations 18 may be selected based on geometric factors, operating parameters as well as on the mechanical properties (e.g., stiffness) of first member 10 and/or second member 14. For example, the spacing between predisposed contact locations 18 may be selected based on the susceptibility of second member 14 to deform (e.g., buckle) under compressive forces and also based on the outer diameter of second member 14 relative to the diameter of lumen 12.
Alternatively, predisposed contact locations 18 may be joined together so as to form a continuous line or surface area for interfacing between inside surface 10A of first member 10 and outside surface 14B of second member 14. For example, in case of second member 14 and center line 14C having a helical shape, predisposed contact locations 18 could comprise a continuous contact line extending helically along which contact between inside surface 10A of first member 10 and outside surface 14B of second member 14 may occur. Also, depending on the configuration of first member 10 and second member 14, predisposed contact locations 18 could include one or more points, one or more lines (e.g., linear, arcuate) and/or one or more surface areas.
The formation of predisposed contact portions 18 by way of sinuous center line 14C and/or sinuous center line 12C may require no additional obstructions such as fins or protrusions that extend from first member 10 and/or second member 14 and that may obstruct flow in passage 16. Accordingly, even though some of the embodiments disclosed herein may cause some additional resistance to fluid flow in passage 16, such flow resistance may be significantly less that would otherwise be encountered with the use of fins or other protrusions.
Medical instrument 200 may comprise first member 10 and second member 14 extending substantially longitudinally in lumen 12. In this embodiment, first member 12 may be permanently formed so that center line 12C or part(s) thereof is/are sinuous so as to define predisposed contact locations 18 between inside surface 10A of first member 10 and outside surface 14B of second member 14 to reduce backlash during relative longitudinal movement between first member 10 and second member 14.
Medical instrument 300 may comprise first member 10 and second member 14 extending substantially longitudinally in lumen 12 of first member 10. In this embodiment, second member 14 may have a tubular configuration and may have its own lumen 20. Second member 14 may be permanently formed so that at least part of center line 14C is sinuous so as to define predisposed contact locations 18 between inside surface 10A of first member 10 and outside surface 14B of second member 14 to reduce backlash during relative longitudinal movement between first member 10 and second member 14.
Medical instrument 300 may comprise insertion tube 22, which is schematically shown in
Medical instrument 400 may comprise first member 10 and second member 14 extending substantially longitudinally in lumen 12 of first member 10. In this embodiment, second member 14 may have a tubular configuration and may have its own lumen 20. First member 10 may be permanently formed so that at least part of center line 12C is sinuous so as to define predisposed contact locations 18 between inside surface 10A of first member 10 and outside surface 14B of second member 14 to reduce backlash during relative longitudinal movement between first member 10 and second member 14. Medical instrument 400 may comprise insertion tube 22, which is schematically shown in
Medical instrument 500 may comprise first member 10 and second member 14 extending substantially longitudinally in lumen 12 of first member 10. First member 10 may be permanently formed so that at least part of center line 12C is sinuous and second member 14 may also be permanently formed so that at least part of center line 14C is also sinuous. However, center line 12C and center line 14C may comprise be non-parallel portions. For example, center line 12C and center line 14C may comprise sinusoidal portions that have different periods so as to define predisposed contact locations 18 between inside surface 10A of first member 10 and outside surface 14B of second member 14 to reduce backlash during relative longitudinal movement between first member 10 and second member 14. Medical instrument 500 may comprise insertion tube 22, which is schematically shown in
Medical instrument 500 may comprising third elongate tubular member 24 having inside surface 24A defining lumen 26 having center line 26C. The characteristics and relationships between third member 24 and first member 10 may be similar to those between first member 10 and second member 14 described above in relation to other embodiments. For example, first member 10 may extend substantially longitudinally in lumen 26 defined by third member 24. First member 10 may extend entirely or only partially in lumen 26. Also, outside surface 10B of first member 10 may cooperate with inside surface 24A of third member 24 to define intermediate longitudinal passage 28 therebetween extending in lumen 26. First member 10 and/or third member 24 may be permanently formed to define predisposed contact locations 30 between inside surface 24A of third member 24 and outside surface 10B of first member 10 to reduce backlash during relative longitudinal movement between first member 10 and third member 24. Passage 28 may be configured to permit the passage of fluid though lumen 26 during irrigation or suction of a treatment site for example. The formation of predisposed contact portions 30 by way of sinuous center line 26C and/or sinuous center line 12C may require no additional obstructions such as fins or protrusions that extend from first member 10 and/or third member 24 and that may obstruct flow in passage 28.
In some embodiments, inside surface 10A of first member 10 and outside surface 10B of first member 10 may be substantially parallel and first member 10 and third member 24 may be permanently formed to have non-parallel portions between center line 12C and center line 26C. In some embodiments, at least part of one of the center line 12C and center line 26C may be sinuous. For example, inside surface 24A of third member 24 may be permanently formed so that at least part of center line 26C is substantially straight while at least part of center line 12C may be sinuous.
Lumen 26 may have a substantially uniform cross-sectional profile along center line 26C where the cross-sectional profile of lumen 26 is substantially perpendicular to center line 26C. Cross-sectional profile of lumen 26 may be substantially circular and provide the advantages described above.
Similarly to medical instrument 500, medical instrument 600 may comprise first member 10, second member 14 and third member 24. First member 10 may be permanently formed so that at least part of center line 12C is sinuous so as to define predisposed contact locations 18 between first member 10 and second member 14 and also define predisposed contact locations 30 between first member 10 and third member 24. In this particular embodiment, both center line 14C and center line 26C are shown as being substantially straight.
Similarly to medical instruments 500 and 600, medical instrument 700 may comprise first member 10, second member 14 and third member 24. Second member 14 may be permanently formed so that at least part of center line 14C is sinuous so as to define predisposed contact locations 18 between first member 10 and second member 14. Third member 24 may be permanently formed so that at least part of center line 26C of lumen 26 is sinuous so as to define predisposed contact locations 30 between first member 10 and third member 24. In this particular embodiment, center line 12C of lumen 12 is shown as being substantially straight.
Described and illustrated herein are several embodiments of medical instruments (e.g., endoscopic instruments and endoscopic systems) having reduced or eliminated backlash during operation. The embodiments described herein do not make use of protrusions or fins that would obstruct flow through fluid passages 16 and 28. Also, the embodiments may provide for convenient seal and attachment of the medical instruments to other devices, accessories and components.
It should be noted that the medical instruments described herein are not limited to work with endoscopes, but could also be used as standalone catheters or parts of catheter systems not requiring an endoscope.
Various aspects of the present disclosure could also be equally applied to multi-lumen instruments and systems. Various aspects of the present disclosure could also be equally applied to the field of industrial endoscopy.
The permanent forming of predisposed contact locations 18, 30 may be achieved during manufacturing so that the components are permanently formed to substantially retain the desired shapes. Alternatively, permanent forming of a component may also include situations where the component retains its desired shape during the relevant use (e.g., reducing backlash during relative movement) of the medical instrument but does not necessarily retains its shape at other times. For example, first member 10, second member 14 and/or third member 24 could comprise flexible or malleable material(s) where the “permanent” sinuous shape may be induced by way of another, more rigid, shaping member inserted therein for example. In some embodiments, first member 10, second member 14 and/or third member 24 could, for example, comprise shape memory material(s) where the sinuous shape may be induced by delivery or removal of energy such as a flow of electric current and/or a change in temperature.
This example presents experimental results that show the reduction in backlash that may be provided using medical instruments according to the present disclosure. For the purpose of the measurements a wavy inner member (i.e., second member 14) was used in conjunction with a straight tubular outer member (i.e., first member 10). To illustrate and quantify the benefits of backlash reduction associated with the movement of the wavy inner member (wire) inside the straight outer member (tube), the following parameters presented in Table 1 were used. In order to simulate the tortuous anatomy of a patient, the tubes (with the wire inside) were wound in two loops of 20 cm diameter at one end.
As expected, the backlash of the baseline straight wires is lower with the larger wire diameters, as they fill the inside of the tubes more. In the extreme case where the outside diameter of the inner wire would be the same as the inside diameter of the tube, the backlash would in theory be zero.
The tables 2-5 below show a significant backlash reduction with the wavy wires in comparison with the straight wires. The highest reduction observed occurred when the peak to peak (PP) value of the wavy wire was similar to the inside diameter of the tube. Furthermore, the lower the period of the waves, which means more contact areas between the tubes and the wires, the greater the backlash reduction.
The experimental results of the backlash reduction are tabulated below. The backlash reduction measurements were acquired using minimal force applied to the inner wires relative to the outer tubes so that there was no significant stretching of the wires. The measurements presented in Tables 2-5 do not include the amount of backlash attributed to the elongation of the wire under load. The total amounts of backlash including the elongation of the wires under load are presented in EXAMPLE 3 below.
This example presents experimental results that show amounts of elongation measured in the inner member (wire) in straight and wavy configurations under the application of forces typically encountered during operation of medical devices as disclosed in the present disclosure. In some cases, typical forces required in manipulation or actuation of endoscopic devices is less than 2 lbs (8.9 N). The results presented in Tables 6-9 provide an indication of how much of the backlash measured (see Examples 1 and 3) may be attributed to the elongation of the wire. As expected, the wavy wires exhibited a higher elongation than the straight wires under the application of the same longitudinal tensile force. The wavy wires used in this example were in accordance with the parameters specified in Table 1.
This example presents calculated amounts of combined elongation and backlash measured on the inner member (wire) in straight and wavy configurations under the application of two lbs of force. Tables 10-13 are essentially a calculated combination of measurements from EXAMPLES 1 and 2 above. The wavy inner wires and outer tubes used in this example were in accordance with the parameters specified in Table 1.
It was observed that the reduction in backlash was lower for a given setup when the diameter of the wavy wire is smaller. This is believed to be a result of the wavy wires stretching during the experiments and the stretching contributing to the backlash. The smaller wire diameter resulted in more elongation than the larger wire diameter under the same applied force.
This example presents experimental results that show the effect of the wavy wire on water flow through the tube (i.e., through passage 16 or 28) in comparison with the presence of a baseline wire of the same diameter but that is straight. This demonstrates the effect of the addition of predisposed contact locations 18 or 30 on the fluid flow through the passage 16 or 18. The wavy inner wires and outer tubes used in this example were in accordance with the parameters specified in Table 1.
Tables 14-16 summarize the flow experiments and show the reduction in water flow under an applied pressure of 3 bar for wavy wires in comparison with a straight wire. As expected, when the ratio of wire outside diameter to tube inside diameter is small, the flow reduction is negligible. Similarly when the period of the waves is lower for a given configuration, the resistance to flow offered by the wire is higher.
The above description is meant to be exemplary only, and one skilled in the relevant arts will recognize that changes may be made to the embodiments described without departing from the scope of the invention disclosed. The present disclosure may be embodied in other specific forms without departing from the subject matter of the claims. Also, one skilled in the relevant arts will appreciate that while the instruments disclosed and shown herein may comprise a specific number of elements/components, the instruments could be modified to include additional or fewer of such elements/components. The present disclosure is also intended to cover and embrace all suitable changes in technology. Modifications which fall within the scope of the present invention will be apparent to those skilled in the art, in light of a review of this disclosure, and such modifications are intended to fall within the appended claims. Also, the scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.
The present application claims priority to U.S. provisional patent application No. 62/104,905 filed on Jan. 19, 2015, the entire contents of which are hereby incorporated by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CA2016/050026 | 1/12/2016 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62104905 | Jan 2015 | US |
