Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M25/00—Catheters; Hollow probes
  • A61M25/01—Introducing, guiding, advancing, emplacing or holding catheters
  • A61M25/0102—Insertion or introduction using an inner stiffening member, e.g. stylet or push-rod
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M25/00—Catheters; Hollow probes
  • A61M25/0043—Catheters; Hollow probes characterised by structural features
  • A61M2025/006—Catheters; Hollow probes characterised by structural features having a special surface topography or special surface properties, e.g. roughened or knurled surface
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M25/00—Catheters; Hollow probes
  • A61M25/0043—Catheters; Hollow probes characterised by structural features
  • A61M2025/0063—Catheters; Hollow probes characterised by structural features having means, e.g. stylets, mandrils, rods or wires to reinforce or adjust temporarily the stiffness, column strength or pushability of catheters which are already inserted into the human body
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/49826—Assembling or joining

Definitions

• the stylet In ventricular shunt applications, the stylet is moved within the catheter axially (in the proximal or distal direction); rotation (sometimes known as "torquing") the stylet around its own axis is generally not required or performed.
• rotation sometimes known as "torquing"
• the adhesion manifests itself as friction that resists the axial motion and therefore may complicate the maintenance of accurate placement of the tip of the catheter; this is particularly a problem when the stylet is withdrawn, as it may lead to loss of the accurate placement of the tip of the catheter by use of the stylet at the outset.
• an improved stylet exhibits reduced adhesion or friction when in contact with silicone materials in the setting described above.
• the stylet is manufactured from non-circular cross-section wire, e.g., wire having cross- sectional geometries that are generally triangular, square, pentagonal, hexagonal, octagonal, and the like; and such non-circular geometries are further defined as being outer surfaces which define at least some additional geometric features such as rounded faces (either concave or convex), rounded corner surfaces, or a combination of both.
• a stylet comprises an elongate stylet body having a proximal end, a distal end, and an outer surface comprising at least three faces.
• the portion having at least three faces may be the entire length of the stylet, or only that distal portion of the length which is within a catheter having a lumen with a circular cross-section. In the latter case, it is preferred that the proximal portion of the stylet have a circular cross-section, so that the "feel" of the stylet in the hand of the surgeon is not changed.
• a method comprises removing a stylet made of a rigid material from a catheter made of an elastomeric material.
• the stylet comprises an elongate stylet body having a proximal end, a distal end and an outer surface comprising at least three faces at least for a portion of its length (for example, only that distal portion of the length which is within a catheter having a lumen with a circular cross-section).
• the method comprises guiding the catheter loaded with the stylet to a desired target; and removing the stylet from the catheter.
• another method comprises manufacturing a stylet to be sufficiently rigid to be easily removed from an elastomeric catheter.
• the method comprises providing the stylet with an elongate stylet body having a proximal end, a distal end and an outer surface comprising at least three faces at least for a portion of its length.
• Figure 1 is a schematic illustration of a portion of a stylet, indicating the direction of a transverse cross-sectional view as A- A, and the direction of a side view as B-B.
• Figures 2-5 are transverse cross-sectional views of various alternative embodiments of a stylet, taken along the line A- A of Figure 1.
• Figures 6 and 7 are schematic cross-sectional views illustrating the fit of conventional and non-conventional stylets within a lumen.
• a very common practice in interventional medical procedures involving a catheter or other elongated object is to include some kind of stiffening member or stylet within the object. This lends a degree of temporary reduction in the flexibility of the catheter so that it may be more easily introduced or guided to its desired location within the patient. Once that is completed, the stylet may be removed. It is common to provide the catheter to the surgical site with the stylet already inserted, or "preloaded" for use.
• Stylets are typically polished stainless steel wires having constant cylindrical cross-sections and smooth outer surfaces. Nonetheless, the softness of catheter materials leads to high amounts of friction that make it difficult to remove the stylet. It is even possible that the catheter will be moved from its desired location, or damaged, or both. Particularly in the delicate context of neurosurgery, neither is desirable.
• One approach is to coat the stylet, for example with PTFE or another lubricious coating. Another is to modify the material of the catheter to reduce friction. Another approach is to modify the stylet cross-section. Yet another is to provide the stylet with some type of surface treatment. An example of surface treatment is the approach taken in US Published Patent Application 2008/0103448.
• the stylet is required to have a circular cross-section (the application disparages non-circular cross-sections as having unsatisfactory "feel"), and the stylet surface is roughened to a specified degree, e.g., peak heights > 30 micrometer.
• the stylets disclosed here are characterized by non-circular cross-sections and further by other geometric features which reduce the amount of contact area between the stylet and the inner diameter of the catheter, but without a loss of satisfactory "feel" or other performance measures.
• a stylet 10 (for clarity, only a portion of which is shown) comprises an elongate body 11 extending between the proximal and distal directions 12, 13 and having an outer surface 14.
• Figure 1 omits shading and contour lines that would suggest the view of the stylet taken in the longitudinal direction (indicated as B-B) or toward the longitudinal axis 16.
• the stylet 10 may be solid or hollow and thus is only schematically depicted as solid in the Figures.
• the outer surface of the stylet is not circular but instead has a complex cross-sectional geometry comprising at least three faces.
• Figure 2 A illustrates three faces 15a-c
• Figure 2B illustrates four (non-labeled) faces
• Figure 2C illustrates six (non-labeled) faces
• Figure 2D illustrates eight (non-labeled) faces, each taken along the view indicated as A- A in Figure 1.
• the stylet 10 is illustrated as solid but in general it could be hollow to any degree desired.
• FIG. 3 illustrates an example of a first alternative embodiment. Specifically, at least one face 15d of the outer surface 14 is concave or convex with respect to the center longitudinal axis 16 of the stylet.
• Figure 3 depicts all six faces as convex; in general, any number of faces, from one to the maximum number present, could be convex; similarly, in general, any number of faces, from one to the maximum number present, could be concave.
• the outline of a regular hexagon is illustrated in dashed lines.
• Figure 4 illustrates an example of a second alternative embodiment. Specifically, a corner surface is defined as the region between immediately adjacent faces of the outer surface— for example, the region indicated as 17a between faces 15e and 15f. At least one corner surface is rounded as opposed to angular because the immediately adjacent faces have tangents (illustrated in dashed lines) which join at a point which does not lie on the corner surface. As before, for purposes of illustration only, Figure 4 depicts all six corner surfaces as rounded, and (independently) all six are rounded to the same degree in terms of shape and size.
• any number of them could be a rounded corner surface; and each corner surface could be different from or the same as any other (although it is preferred that they all be the same as each other regardless of the shape or degree of roundness, to lend symmetry to the stylet).
• Figures 6 and 7 are a comparative study of the fit of a conventional round cross-section stylet ( Figure 6) and a six-faced concave-rounded embodiment (Figure 7), each within a catheter lumen 20 which has circular inner diameter 21.
• the conventional circular cross-section stylet fits tightly against the inner diameter 21 of the lumen 20 over a substantial amount of arc— approximately 1 15 degrees, or roughly one-third of the circumference. (The exact amount will depend on the relative sizes of the stylet and lumen. In the example shown here, the stylet area is approximately 5% smaller than the area of lumen and no deflection of the inner diameter is considered.)
• the stylet of Figure 7 intersects over a larger number of contact locations (six, corresponding to the number of rounded corner surfaces 17c), but each contact location has a small amount of contact in terms of arc— approximately 10 to 12 degrees as illustrated.
• the total amount of contact area is only approximately 60 to 72 degrees, or approximately 50 to 65 percent as much area as the conventional fit. Because the amount of friction between the stylet and the inner diameter of the lumen depends on the amount of contact area, this is a substantial reduction.
• typical conventional catheter diameters have outer diameter on the order of 2.5 mm (between 7 Fr and 8 Fr) but inner diameter only on the order of 1.0 to 2.0 mm— and the stylets are necessarily smaller than the catheter inner diameter.
• the stylets are not very large to begin with.
• a reduction in stylet cross- sectional area on the order of 5% results in a very small reduction in the amount of stylet material and thus may not have an appreciable impact on "feel" and other related issues.
• the cross- sectional area of the stylet is approximately 90% of the cross-sectional area of the conventional stylet of Figure 6, but this ratio can be increased by decreasing the concavity of the faces beyond the extent shown here for clarity only.
• cross-sectional geometry could vary over the length of the stylet, it is preferred that at least for a majority of the stylet body length (and, most preferably, for essentially its entire length), the geometry remain essentially if not exactly identical.
• the stylet is non-circular in cross-section over its distal portion (most preferably the portion within the catheter lumen), but its proximal portion is circular in cross-section so that the "feel" of the stylet in the hand of the surgeon is not changed.
• US Published Patent Application 2008/0103448 discloses a surface treatment of a stylet which is required to have a circular cross- section, non-circular cross-sections being criticized as having unsatisfactory "feel". In principle, such surface treatment may be applied to the surfaces of the non-circular cross-section stylets described in this application, if desired. Therefore, the entire contents of US Published Patent Application 2008/0103448 is incorporated by reference as if set forth in full.
• that process treats, or roughens, the outer surface of the stylet body, preferably by a glass peening or a bead blasting operation, such that its maximum profile peak height is greater than 30 micrometer, its roughness average is greater than 5 micrometer, and its root-mean-square roughness is greater than 8 micrometer.
• the stylet is subjected to a known peening process, in which metal or glass shot is bombarded against the surface of the stylet with suitable intensity and overlapping coverage.
• glass shot of about 100 micrometer is used for at least 10 minutes in an intensity range between 30- 60 psi.
• the resulting treated stylet it is desirable for the resulting treated stylet to have a removal force from a catheter of less than 0.8 lbf, more preferably about 0.1 lbf. Removal force is measured as described in that publication and the publicly available standards documents which it relies upon.
• one preferred application of the improved stylet is in a "preloaded" configuration.
• the stylet is provided to the surgical site already loaded within a catheter.
• the primary (if not sole) function of the stylet is to provide sufficient stiffness to the catheter to assist a user in guiding the catheter to its desired location in a patient, after which the stylet is withdrawn and discarded.

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• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Biophysics (AREA)
• Pulmonology (AREA)
• Engineering & Computer Science (AREA)
• Anesthesiology (AREA)
• Biomedical Technology (AREA)
• Heart & Thoracic Surgery (AREA)
• Hematology (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Media Introduction/Drainage Providing Device (AREA)
• Materials For Medical Uses (AREA)
• Measurement And Recording Of Electrical Phenomena And Electrical Characteristics Of The Living Body (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

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Cited By (2)

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Citations (7)

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• 2011
  • 2011-10-18 US US13/276,155 patent/US20130096482A1/en not_active Abandoned
• 2012
  • 2012-10-17 JP JP2014537177A patent/JP2015500672A/ja active Pending
  • 2012-10-17 CN CN201280051556.2A patent/CN104105523B/zh not_active Expired - Fee Related
  • 2012-10-17 AU AU2012326184A patent/AU2012326184B2/en not_active Ceased
  • 2012-10-17 WO PCT/US2012/060619 patent/WO2013059324A1/en not_active Ceased
  • 2012-10-17 EP EP12780999.4A patent/EP2768565A1/en not_active Withdrawn
  • 2012-10-17 CA CA2852242A patent/CA2852242A1/en not_active Abandoned
• 2018
  • 2018-07-12 JP JP2018132160A patent/JP2018187418A/ja active Pending

Patent Citations (7)

Non-Patent Citations (1)

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