U.S. patent application number 17/008226 was filed with the patent office on 2020-12-24 for device and method for inhibiting movement of a medical device in a patient.
This patent application is currently assigned to Becton, Dickinson and Company. The applicant listed for this patent is Becton, Dickinson and Company. Invention is credited to Amit Limaye, Nathaniel McCaffrey, James Petisce.
Application Number | 20200397951 17/008226 |
Document ID | / |
Family ID | 1000005062911 |
Filed Date | 2020-12-24 |
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United States Patent
Application |
20200397951 |
Kind Code |
A1 |
Petisce; James ; et
al. |
December 24, 2020 |
Device and Method for Inhibiting Movement of a Medical Device in a
Patient
Abstract
A medical device such as a cannula, catheter, needle or
biosensing probe includes an elongated body for penetrating,
inserting and/or positioning in or through the skin of a patient.
The elongated body has an outer surface that when positioned in the
patient with a coefficient of friction sufficient to inhibit
movement between the elongated body on the skin at the insertion
site to inhibit irritation at the infusion site. A lubricious
coating is provided on the elongated body to assist in penetration
and/or insertion of the elongated body into the patient. The
lubricious coating can be removed by a shearing action by the
insertion of the elongated body into the patient and/or by
absorption of the lubricious coating to expose the outer surface of
the elongated member.
Inventors: |
Petisce; James; (Westford,
MA) ; McCaffrey; Nathaniel; (Mill Valley, CA)
; Limaye; Amit; (Wayne, NJ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Becton, Dickinson and Company |
Franklin Lakes |
NJ |
US |
|
|
Assignee: |
Becton, Dickinson and
Company
Franklin Lakes
NJ
|
Family ID: |
1000005062911 |
Appl. No.: |
17/008226 |
Filed: |
August 31, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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14654493 |
Jun 19, 2015 |
10799621 |
|
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PCT/US2012/070870 |
Dec 20, 2012 |
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17008226 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04C 2270/041 20130101;
A61M 2005/1588 20130101; A61L 29/14 20130101; A61L 29/085 20130101;
C12Q 1/006 20130101; A61L 2400/10 20130101; G01N 33/66 20130101;
A61L 29/16 20130101; A61L 2430/00 20130101; A61M 25/0045 20130101;
A61M 2230/201 20130101; A61L 31/10 20130101; A61B 5/6852 20130101;
A61M 2205/0238 20130101; A61L 2420/06 20130101; A61B 5/14503
20130101; A61B 5/14532 20130101; A61M 5/158 20130101; A61L 29/148
20130101 |
International
Class: |
A61L 29/08 20060101
A61L029/08; A61M 25/00 20060101 A61M025/00; A61B 5/145 20060101
A61B005/145; A61B 5/00 20060101 A61B005/00; A61L 29/14 20060101
A61L029/14; A61L 29/16 20060101 A61L029/16; A61M 5/158 20060101
A61M005/158; G01N 33/66 20060101 G01N033/66; C12Q 1/00 20060101
C12Q001/00; A61L 31/10 20060101 A61L031/10 |
Claims
1. A medical device comprising: an elongated body having an outer
distal surface at a distal end and an outer proximal surface
oriented proximally of said distal surface, said distal end of said
device adapted for inserting into or through the skin of a patient;
an inner lubricant coating on said distal surface; an outer
lubricant coating on said inner lubricant coating and on said
proximal surface to assist insertion of said elongated body into
said skin, said outer lubricant coating being removable during use
of said medical device to expose said inner lubricant coating and
said proximal surface of said elongated body; said proximal surface
of said elongated body having at least a portion thereof with a
coefficient of friction higher than said outer lubricant coating to
inhibit movement of said elongated body with respect to the skin
after insertion and to inhibit irritation of the skin.
2. The medical device of claim 1, wherein said elongated body is
selected from the group consisting of a cannula, sensor, probe, an
intravenous needle, and a glucose monitoring probe adapted for
positioning in or below the skin of the patient to monitor glucose
blood levels.
3. The medical device of claim 1, wherein said inner lubricant
coating remains on said distal surface after removal of said outer
lubricant coating, and said inner lubricant coating is
biodegradable to form a textured surface after removal of said
outer lubricant coating.
4. The medical device of claim 1, wherein said outer lubricant
coating is a water soluble, uncrosslinked silicone lubricant, and
said inner lubricant coating is a crosslinked silicone
lubricant.
5. The medical device of claim 1, wherein said outer lubricant
coating is removable from said elongated body during or after
insertion to expose said proximal surface of said elongated body
and said inner lubricant coating.
6. The medical device of claim 5, wherein said outer lubricant
coating comprises a water based uncrosslinked lubricant.
7. The medical device of claim 5, wherein said outer lubricant
coating is removable from said elongated body by contact with body
fluids to expose said proximal surface of said elongated body and
said inner lubricant coating.
8. The medical device of claim 5, wherein said outer lubricant
coating is removable from said elongated body by a shearing action
upon insertion of said elongated body in the skin.
9. The medical device of claim 1, wherein said inner lubricant
coating has a coefficient of friction greater than a coefficient of
friction of said outer lubricant coating to resist movement of said
elongated body after insertion and removal of said outer lubricant,
and a coefficient of friction less than a coefficient of friction
of said proximal surface of said elongated body.
10. The medical device of claim 1, wherein said proximal surface of
said elongated body defines a contact area for contacting the skin
after insertion, said contact area having a textured surface to
inhibit movement of said elongated body with respect to said skin
and inhibit irritation of said skin after insertion.
11. The medical device of claim 1, wherein said proximal surface of
said elongated body includes an inner coating that is at least
partially bioabsorbable to form a textured surface after insertion
of said elongated body and removal of said outer lubricant
coating.
12. A biosensor probe for inserting intravenously or into or
through the skin of a patient, said biosensor probe comprising: an
elongated body having a sensor for detecting an analyte, said
elongated body having an outer distal surface oriented at a distal
end, an outer proximal surface oriented proximally of said distal
surface; an inner lubricant coating on said distal surface of said
elongated body; a removable outer lubricant coating on said inner
lubricant coating and on said proximal surface, said outer
lubricant being removable during use of said probe to expose said
inner lubricant coating and said proximal surface of said elongated
body; and said proximal surface of said elongated body having a
contact area with a surface adapted for providing a coefficient of
friction higher than a coefficient of friction of said outer
lubricant coating to resist movement of said probe relative to the
skin after insertion, and said inner lubricant coating is at least
partially bioabsorbable or biodegradable to form a textured surface
after removal of said outer lubricant coating.
13. The biosensor probe of claim 12, wherein said outer lubricant
coating is removable from said elongated body during or after
insertion of said elongated body into said skin to expose said
proximal surface.
14. The biosensor probe of claim 12, wherein said inner lubricant
coating comprises a crosslinked silicone polymer provided at said
distal end, and said outer lubricant coating comprises an
uncrosslinked silicone lubricant overlying said inner lubricant
coating at said distal end and said proximal surface.
15. The biosensor probe of claim 12, wherein said outer lubricant
coating is removable from said elongated body by contact with body
fluids of the patient to expose the proximal surface of the
elongated body, or by a shearing action by insertion of said probe
in the skin.
16. The biosensor probe of claim 12, wherein said inner lubricant
coating has a coefficient of friction higher than a coefficient of
friction of said outer lubricant coating and has a coefficient of
friction sufficient to inhibit movement of said elongated body with
respect to the skin and inhibit irritation of the skin by sliding
movement.
17. The biosensor probe of claim 12, wherein said proximal surface
of said elongated body has a textured surface with a coefficient of
friction sufficient to inhibit movement between said biosensor and
the tissue and to a lubricity sufficient to allow removal of said
biosensor with reduced irritation to the patient.
18. The biosensor probe of claim 12, wherein said proximal surface
of said elongated body includes a tissue growth promoting component
for promoting tissue growth at an insertion site of said probe.
19. A method of inhibiting movement of a medical device inserted
through the skin of a patient, said method comprising the steps of:
providing the medical device according to claim 1; inserting said
elongated body into or through the skin of the patient such that
the outer lubricant coating assists insertion of the elongated body
into the skin, and removing said outer lubricant coating during or
after insertion to expose said proximal surface of said elongated
body and inner lubricant coating to inhibit movement of the
elongated body with respect to the skin after insertion.
20. The method of claim 19, wherein said medical device is selected
from the group consisting of a cannula, and a biosensor probe., and
a glucose.
21. The method of claim 19, wherein said medical device is a
glucose monitoring probe having a glucose detecting component, said
method comprising monitoring glucose levels in the patient.
22. The method of claim 19, wherein said outer lubricant coating
comprises an uncrosslinked silicone lubricant, and said inner
lubricant coating comprises a crosslinked silicone lubricant.
23. The method of claim 19, comprising removing outer lubricant
coating by contact with body fluids, or removing said outer
lubricant coating by a shearing action upon insertion of said
medical device into the patient.
24. The method of claim 19, wherein said inner coating is at least
partially bioabsorbable and said method comprises inserting said
elongated body in the skin for a time sufficient to erode at least
part of a surface thereof to form a roughened surface in contact
with said skin to inhibit movement of said elongated body with
respect to said skin.
Description
[0001] This application is a divisional application of U.S. Ser.
No. 14/654,493, filed on Jun. 19, 2015, which is a 371 of
PCT/US2012/070870, which are hereby incorporated by reference in
their entireties.
FIELD OF THE INVENTION
[0002] The present invention is directed to a device and method for
facilitating insertion and inhibiting movement of a medical device
with respect to the tissue at an insertion site in a patient. In
particular, the invention is directed to a medical device having a
lubricated portion for inserting into the patient and having a
surface to limit or resist movement of the device at the insertion
site after insertion.
BACKGROUND OF THE INVENTION
[0003] A cannula such as a hypodermic needle and a catheter are
commonly used for delivering and withdrawing fluids from a patient.
Hypodermic needles are typically coated with a suitable lubricant
to assist with penetration into the skin with reduced pain to the
patient.
[0004] Tissue penetration by a hypodermic needle causes several
events that cause pain to the patient. The distal tip of the needle
contacts the skin and stretches the skin until the tip cuts into
the skin. As the shaft of needle penetrates the tissue, a sliding
friction occurs between the surface of the needle and the tissue.
The drag caused by the friction between the surface of the needle
and the tissue contributes to the pain perceived by the patient. A
lubricant on the shaft of the needle can reduce the drag force and
reduce the pain perceived by the patient.
[0005] Catheters are also inserted into or through the skin of a
patient to deliver or withdraw fluid to the patient. One example is
an insulin delivery device for delivering a continuous or steady
supply of insulin or other medication over prolonged period of
time. Another example is an infusion set having a needle or
catheter that is inserted through the skin at an infusion site. The
infusion set typically includes a base that is attached to the
surface of the skin by an adhesive. The infusion set is retained in
place with the needle or catheter penetrating the skin for an
extended period of time from several days to several weeks to
deliver a suitable dosage of the insulin or other medication.
[0006] Diabetes requires the continuous maintenance of proper
insulin dosages to the patient. To monitor the blood glucose levels
in the patient, various methods and devices have been used. One
device draws a sample of blood from the patient, typically by a
finger stick method. A glucose sensor then measures the blood
glucose level and displays the value on a suitable display.
[0007] Another type of glucose monitoring device includes a probe
that is inserted into the tissue of the patient to detect glucose
in body fluids such as blood. The probe includes a glucoses sensor
such as a glucose binding protein, or glucose oxidase to monitor
the blood glucose level on a continuous basis.
[0008] The infusion set and the glucose sensor probe can remain in
the tissue for days or weeks to provide sustained delivery of the
insulin and continuous monitoring of the patient's blood glucose
level. The infusion set and probe are secured to the outer surface
of the skin to hold the device in place and maintain proper
placement and positioning of the catheter or probe in the
tissue.
[0009] Prolonged usage of the catheter of the infusion set or probe
causes irritation and inflammation at the site of penetration. The
device must be periodically replaced at a new site and the new
device must again penetrate the skin, typically through use of an
insertion needle, thereby causing pain and discomfort to the
patient.
[0010] While the prior devices have been generally suitable for
their intended use, there is a continuing need in the industry for
improved devices that reduce or minimize discomfort to the patient
and irritation to the skin.
SUMMARY OF THE INVENTION
[0011] The present invention is directed to a medical device and to
a method for inhibiting or limiting movement of the medical device
at an insertion site in the patient. In particular, the invention
is directed to a medical device adapted for insertion into a
patient and having an outer surface that resists or limits movement
between the device and the tissue at the insertion site.
[0012] Accordingly, one feature of the invention is to provide a
medical device such as a cannula, needle, catheter, probe or
biosensor adapted for insertion into the patient in a manner to
inhibit, minimize or resist movement of the medical device at the
insertion site after insertion and to inhibit irritation and trauma
of the insertion site caused by movement of the medical device. The
medical device includes a lubricated outer surface to minimize
trauma to skin and/or vein during or after insertion.
[0013] One aspect of the present invention is directed to a medical
device that penetrates the skin or is inserted into the patient and
remains in place in the patient for an extended period of time.
Examples of such medical devices include a cannula, a catheter of
an insulin infusion set or insulin infusion pump or a probe of a
biosensor for monitoring analytes in the patient. Another example
is a probe of a blood glucose monitoring device.
[0014] The medical device of the invention has an elongated body
that is inserted into the patient at an insertion site. The outer
surface of the elongated body that contacts the tissue at the
insertion site is modified to inhibit or limit sliding movement of
the elongated body with respect to the insertion site after
insertion. Limiting movement of the elongated body at the insertion
site reduces irritation and inflammation of the tissue at the
insertion site during extended use of the medical device.
[0015] Another feature of the invention is to provide a medical
device adapted for inserting into the patient for an extended
period of time where the medical device is able to move into the
insertion site with reduced irritation and inflammation at the
insertion site.
[0016] The features and advantages of the invention are provided by
a medical device adapted for insertion into a patient and worn for
an extended period of time by the patient where an outer surface of
the medical device has a coefficient of friction at the interface
of the insertion site to inhibit or limit movement of the medical
device at the insertion site while providing sufficient lubricating
properties to assist in removal of the medical device with minimal
pain and discomfort to the patient.
[0017] Another feature of the invention is to provide a medical
device adapted for inserting into a patient and to be worn by the
patient for an extended period of time where the device has a
lubricious coating to assist in insertion of the medical device and
a contact surface for contacting the insertion site after insertion
into the patient. The contact surface of the medical device has a
coefficient of friction higher than the lubricious coating to
inhibit prolonged movement of the medical device between the
medical device and tissue interface at the insertion site during
wear after insertion.
[0018] The various advantages and features of the invention are
provided by a medical device having an elongated body adapted for
inserting into the patient, where the elongated body includes a
lubricious coating to assist penetration an insertion of the
elongated body into an insertion site. The lubricious coating can
be removed by a shearing action by the insertion and drag force of
the elongated body to expose an outer surface of the elongated
body. The outer surface of the elongated body has a coefficient of
friction that is higher than a coefficient of friction of the
lubricious coating to resist or limit movement between the
elongated body and the insertion site to reduce irritation and
inflammation at the insertion site.
[0019] The features of the invention are provided by a biosensor
probe having an outer surface and a lubricious coating to assist
insertion of the probe into a patient. The lubricious coating can
be removed upon insertion into the patient. Alternatively or in
addition, the lubricious coating is removed after insertion into
the patient to expose the outer surface of the probe. The
lubricious coating can be soluble or bioabsorbable by body fluids
at the infusion site. The outer surface of the probe can have a
textured or roughened surface or an inner coating layer to provide
the probe with a coefficient of friction sufficient to resist
sliding at an interface between the probe and the tissue at the
insertion site. The inner coating can be at least partially
degradable to produce a surface having a texture with a coefficient
of friction to inhibit sliding movement between the probe and the
tissue at the insertion site.
[0020] Another aspect of the invention is to provide a medical
device for insertion into a patient where the outer surface of the
medical device has a tissue growth promoting component and a
coating of a lubricious material. The tissue growth promoting
component promotes tissue growth at the insertion site of the
device to inhibit movement of the device at the insertion site
after deployment.
[0021] These and other aspects of the invention are attained by
providing a medical device comprising an elongated body having an
outer surface, a distal end and a proximal end. The distal end of
the device is adapted for inserting into the skin of a patient. An
outer lubricious coating is applied at least at the distal end on
the outer surface to assist insertion in the skin by the elongated
body. The outer surface of the elongated body has at least a
portion thereof with a coefficient of friction higher than the
lubricious coating to inhibit movement of the elongated body with
respect to the skin after insertion and to inhibit irritation of
the skin.
[0022] The various features of the invention are further attained
by providing a biosensor probe for penetrating and inserting in the
skin of a patient. The biosensor probe comprises an elongated body
having a sensor for detecting an analyte, a proximal end, a distal
end and an outer surface. A lubricious coating is applied at least
to the distal end of the elongated body to assist penetration of
and insertion in the skin of the patient. The elongated body has at
least one contact area with a surface adapted for providing a
coefficient of friction higher than a coefficient of friction of
the lubricious coating to resist movement of the cannula relative
to the skin after insertion.
[0023] The advantages and features of the invention are also
attained by providing a method of inhibiting movement of a medical
device inserted through the skin of a patient. The method comprises
the steps of providing the medical device with an elongated body
having a distal end, a proximal end, an outer surface and a
lubricious coating on the outer surface at least at the distal end.
The outer surface of the elongated body has a coefficient of
friction greater than a coefficient of friction of the lubricious
coating. The elongated body is inserted in the skin of the patient
where the lubricious coating assists insertion of the elongated
body in the skin and where the outer surface of the elongated body
contacts the skin to inhibit or minimize movement of the elongated
body with respect to the skin after insertion.
[0024] The various objects, advantages and salient features of the
invention will become apparent from the following detailed
description of the invention, which in conjunction with the
drawings, disclose various embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The following is a brief description of the drawings, in
which:
[0026] FIG. 1 is a schematic view of the probe sensor in one
embodiment of the invention;
[0027] FIG. 2 is a cross-sectional view of the probe;
[0028] FIG. 3 is a partial view of the probe inserted into a
patient;
[0029] FIG. 4 is a partial cross-sectional view showing the probe
with a single coating;
[0030] FIG. 5 is a cross-sectional view of the probe showing a
coated tip and an overcoat layer;
[0031] FIG. 6 is a side view of a cannula having a lubricious
coating;
[0032] FIG. 7 is a cross-sectional view of the cannula showing the
layers of the coating;
[0033] FIGS. 8A and 8B are graphs showing the force of an uncoated
needle of Example 1;
[0034] FIGS. 9A and 9B are graphs showing the force of a needle
coated with a crosslinked lubricant of Example 2;
[0035] FIGS. 10A and 10B are graphs showing the force of a needle
coated with an uncrosslinked lubricant of Example 3;
[0036] FIGS. 11A and 11B are graphs showing the force of a needle
with a crosslinked lubricant on the tip of Example 4;
[0037] FIGS. 12A and 12B are graphs of a needle with a crosslinked
lubricant on the tip and an overcoat of an uncrosslinked lubricant
of Example 5; and
[0038] FIG. 13 is a graph comparing the data of Examples 1-5.
DETAILED DESCRIPTION OF THE INVENTION
[0039] The present invention is directed to a medical device that
can be inserted into the tissue of a patient. The invention is
particularly directed to a medical device adapted for insertion
into the tissue of a patient for extended periods of time with
reduced irritation and inflammation at the insertion site. In the
various embodiments described herein, the medical device can be a
sensor probe for sensing and measuring an analyte concentration in
body fluids. One particular example is a glucose sensor probe for
the continuous monitoring of glucose blood levels in a patient. In
other embodiments, the medical device can be an insulin infusion
set having a cannula, a needle or catheter for delivering insulin
or other medicaments to the patient. It will be understood that the
cannula and probe are intended to be exemplary and that the
invention is suitable for other medical devices that are adapted
for penetrating the skin of a patient and are adapted to be
retained in the tissue of the patient for extended periods of
time.
[0040] A cannula, needle or probe is adapted to be inserted into
the tissue of a patient and remain in the tissue for extended
periods of time depending on the device and its intended use. For
example, a glucose sensor probe of a glucose monitor is generally
intended to remain in the insertion site for at least a day to more
than one week. The medical device can be inserted intravenously,
cutaneously or subcutaneously depending on the structure and
intended use of the medical device.
[0041] The longer the time the probe or cannula remains in the
insertion site in the tissue, the greater the risk of irritation
and inflammation of the tissue at the insertion site. It has been
found that during normal use and movement by a patient, the probe
or cannula will move slightly in an inward and outward direction
causing irritation. Such movement is generally referred to as
"pistoning" which causes irritation and inflammation at the
insertion site. The movement of the probe or cannula relative to
the insertion site creates a drag or friction causing irritation
and inflammation. The irritation of the tissue at the insertion
site typically leads to an inflammatory response at the insertion
site. In a probe having a glucose sensor, the resulting
inflammatory response will often compromise the sensor accuracy and
responsiveness.
[0042] The medical device of the present invention can be a probe,
cannula or needle that has a suitable coating to provide easy
insertion into the tissue to minimize trauma and discomfort during
insertion and has a surface that comes into contact with the tissue
after insertion that minimizes movement between the device and the
tissue interface. The invention is particularly directed to a
medical device that has a lubricious coating to provide the
necessary lubricity to facilitate penetration and/or insertion into
the tissue of the patient while providing a surface having a
reduced lubricity after insertion to reduce or limit movement of
the device relative to the tissue at the insertion site. The
lubricity is selected to reduce the pistoning effect when worn by
the patient for extended periods of time. Examples of suitable
analyte sensors or probes are disclosed in U.S. Pat. Nos. 7,310,544
and 7,713,574, which are hereby incorporated by reference in their
entirety.
[0043] In one embodiment of the invention, the medical device is a
probe having an immobilized sensor for sensing an analyte that can
be inserted and immobilized in the tissue of a patient. The probe
is adapted for insertion into the patient and can be worn for an
extended period of time. A probe or other device that is not
lubricated can require a high insertion force to break the skin and
can cause high friction forces against the tissue to continue
inserting the probe through the skin resulting in end user
discomfort. Unlubricated probes can cause discomfort to the patient
during insertion and can cause local inflammation, repeated
aggravation and injury. The microscopic movement of the probe
relative to the tissue occurs as a result of the normal use and
wearing of the probe. The movement of the probe can cause
discomfort at the insertion site and local accumulation of blood
components to alleviate the inflammation. The accumulation of the
blood components can hinder the performance of the sensor and
particularly a blood glucose sensor. The irritation and
inflammation also can result in reduced wearing time by the patient
and a greater need to relocate the probe to different sites.
[0044] Referring to the drawings, various exemplary embodiments are
shown. In the embodiment shown in FIG. 1, the medical device 10
includes a probe 12 adapted for inserting in the tissue of a
patient as known in the art. The probe 12 in the embodiment
illustrated includes a glucose sensor capable of detecting glucose
levels in the body fluid. The probe is connected by a wire or
optical fiber 14 to a glucose monitoring system 16. The glucose
monitoring system 16 as known in the art receives signals from the
probe 12 and calculates a blood glucose level which can be
displayed or recorded by the system. Examples of such glucose
monitoring systems are known in the art.
[0045] Referring to FIG. 2, the probe 12 in one embodiment of the
invention includes an elongated body 18 which can be rigid or
flexible. A proximal end 20 is connected to the wire 14. A distal
end 22 supports the glucose sensing unit 24. The glucose sensing
unit 24 in one embodiment of the invention can include a glucose
binding protein, or a glucose oxidase sensor. The probe has a
length and a diameter suitable for inserting in the tissue site and
can be inserted into the patient by procedures, locations and
depths as known in the art. The medical device can have a sharpened
tip, insertion needle or other insertion device as known in the art
for inserting and positioning a probe, cannula or other medical
device in a patient and at a suitable depth of penetration
depending on the intended use of the medical device. Examples of
suitable glucose binding proteins and glucose monitoring probes are
disclosed in U.S. Pat. No. 6,277,627 to Hellinga, U.S. Pat. No.
7,064,103 to Pitner et al., and U.S. Pat. No. 7,326,538 to Pitner
et al., and U.S. Patent Publication No. 2008/0275318 to Lastovich
et al., which are hereby incorporated by reference in their
entirety.
[0046] In the embodiment of FIG. 2, the probe includes an inner
coating 26 and an outer lubricious coating 28 applied over the
inner coating 26. The outer coating 28 forms a lubricated coating
to assist in penetration, insertion and positioning of the probe
through the insertion site 32 in the tissue 30 of a patient. The
lubricant can be a suitable lubricant known in the art. One example
of a suitable lubricant is a polydimethyl siloxane. The inner
coating 26 is a polymeric material bonded to the outer surface of
the probe 18. The probe surface 18 is generally made of a polymeric
material such as a polyurethane, silicone resin. The inner coating
26 is applied to the outer surface of the probe around the entire
outer surface. An adhesion promoter can be incorporated into the
polymeric material as needed.
[0047] In one embodiment shown in FIG. 2, the inner coating 26
extends from the distal end 22 of the probe 18 along a length of a
contact area sufficient to contact the tissue at the insertion site
after insertion and positioning in the patient.
[0048] In one embodiment of the invention, the outer lubricious
coating 28 is a relatively soft material that can be wiped from the
inner coating 26 and the probe upon insertion into the tissue.
[0049] Referring to FIG. 3, the probe 12 is inserted into the
tissue 30 of a patient at an insertion site 32. The outer
lubricious coating 28 contacts the tissue at the insertion site 32
during insertion to assist in the penetration of the probe 12 and
reduce frictional drag forces between the probe 12 and the tissue
30. In the embodiment shown in FIG. 3, the lubricious coating 28 is
completely or partially removed by the insertion into the tissue at
the insertion site 32 to expose the inner coating 26. The inner
coating 26 has a lubricity that is less than the outer lubricious
coating and coefficient of friction greater than a coefficient of
friction of the outer lubricious coating 28. The inner coating 26
when exposed to the tissue forms an outer surface with a sufficient
static and/or dynamic coefficient of friction to minimize, resist
or limit movement of the probe with respect to the tissue and
reduce the pistoning effect. By providing the inner coating with a
sufficient static and/or dynamic coefficient of friction, movement
of the tissue by the patient allows the probe to move together with
the tissue at the insertion site 32 and limit sliding movement of
the probe with respect to the tissue. In a similar manner, small
movement of the probe enables the tissue at the insertion site 32
to move with the small movements of the probe. By reducing or
preventing the sliding motion in or out of the tissue and relative
movement of the probe with respect to the tissue at the insertion
site 32, inflammation and irritation of the tissue at the insertion
site can be reduced.
[0050] The outer lubricious coating 28 can be a soft or low
viscosity lubricant. The lubricious coating is preferably
sufficiently viscous to remain on the outer surface of the inner
coating 26 and to provide sufficient lubrication of the probe
during insertion into the tissue site. The viscosity of the
lubricant in this embodiment is preferably sufficiently low that
the drag forces during insertion remove at least a portion of the
lubricious coating to expose the inner coating 26.
[0051] The lubricant used to form the outer lubricious coating can
be any suitable lubricant as known in the art that is capable of
providing the necessary lubricity for initial penetration and
insertion of the medical device into the tissue. One example of a
lubricant that can be removed or partially removed from the medical
device such as a probe or cannula by the drag force or friction
with the tissue at the insertion site is an uncrosslinked lubricant
such as a water based lubricant. A suitable water based lubricant
can be a water based silicone polymer lubricant having a lubricity
sufficient to lubricate the surface of the medical device to allow
ease of insertion with reduced pain and discomfort to the patient.
The water based silicone lubricant can be easily coated onto the
surface of the medical device and removed by the insertion drag
force. Alternatively or in addition, the water based lubricant can
be removed completely or partially after insertion into the tissue
by dissolving or dispersing in the body fluids to expose the
surface of the medical device having the coefficient of friction
necessary to limit the sliding movement of the medical device with
respect to the insertion site during normal use and wear of the
medical device. One example of a silicone surfactant is a
polydimethyl siloxane having a molecular weight of 20,000 and a
viscosity of 1700 centistokes and is soluble in water. A suitable
water based silicone lubricant is disclosed in U.S. Pat. No.
4,664,657 to Williamitis et al. and U.S. Pat. No. 5,688,747 to Khan
et al. which is hereby incorporated by reference in its
entirety.
[0052] The inner coating 26 can be a polymeric coating that can be
permanently fixed to the outer surface of the probe. The inner
coating 26 can also be made from a biodegradable or bioabsorbable
polymer such as a polylactic acid which can degrade and be absorbed
at the tissue site. The degradation at the surface of the inner
coating 26 can produce a textured or roughened surface at the
tissue site caused by the body fluids to provide the necessary
coefficient of friction to prevent slippage or movement of the
probe relative to the insertion site. In various embodiments of the
invention, the inner coating 26 can include various active agents
or pharmaceutical agents such as a tissue growth agent to promote
tissue growth at the insertion site and to attach the tissue to the
probe, thereby preventing or minimizing relative movement between
the probe and the insertion site.
[0053] The inner coating applied to the surface of the medical
device between the surface of the medical device and the lubricant
formulated a biodegradable or bioabsorbable polymer coating. In one
embodiment of the invention, the inner coating is able to at least
partially degrade, dissolve or disperse in the body fluids from the
insertion site to produce a surface texture on the coating and/or
the medical device that provides the desired coefficient of
friction to inhibit the excessive movement of the medical device at
the insertion site by normal movement by the patient. The
biodegradable coating can be tailored to erode at a predetermined
rate to provide a surface texture of the coating within a selected
period of time after insertion and exposure to the body fluids. The
textured surface of the inner coating preferably has a coefficient
of friction greater than the outer lubricant used for insertion of
the medical device. Examples of biodegradable polymers include
polylactic acid polymers, polyanhydride polymers, hydroxybutyrate
polymers, polyvinyl alcohol polymers, polycaprolactone polymers,
starch derivatives and cellulose derivatives.
[0054] In one embodiment, the inner coating that comes into contact
with the tissue at the insertion site can include a growth
promoting substance such as growth factor in an amount sufficient
to promote tissue growth at the insertion site. The growth
promoting substance is preferably able to promote tissue growth at
the interface of the medical device and tissue provide the
necessary drag force by the tissue to reduce the movement between
the medical device and the tissue at the insertion site.
[0055] The inner coating and/or the lubricant coating can also
contain other bioactive agents such as an antimicrobial agent or
antibacterial agent. Other bioactive agents include
anti-inflammatory agents, an enzyme, a hormone, a therapeutic drug,
a vitamin, an antibody, antigen, nucleic acid, a protein or
peptide, a polysaccharide or heparine.
[0056] In another embodiment of the invention shown in FIG. 4, the
probe 12 includes a single coating 34 on the outer surface of the
elongated body 36 of the probe. The coating 34 has a coefficient of
friction to enable easy insertion of the probe into the insertion
site in the tissue in the manner shown in FIG. 3. The lubricious
coating 34 can be biodegradable or bioabsorbable as in the previous
embodiment. In this embodiment, the probe is inserted into the
tissue at the insertion site where the body fluids dissolve or
decompose the lubricious coating 34 after insertion. The lubricious
coating 34 dissolves or degrades to expose the outer surface of the
probe 36.
[0057] In this embodiment, the outer surface of the probe has a
coefficient of friction greater than the coefficient of friction of
the lubricious coating. As the lubricious coating 34 is dissolved
or absorbed, the outer surface of the probe is exposed and comes
into contact with the tissue at the insertion site. The surface of
the probe 36 having a coefficient of friction greater than the
coefficient of friction of the lubricious coating provides
sufficient frictional drag force between the probe and the tissue
at the insertion site to inhibit relative movement between the
probe and the insertion site. In this embodiment, the outer surface
of the probe has a textured or roughened surface to provide the
necessary coefficient of friction. The textured outer surface can
be obtained by mechanical means or by a chemical means. The
textured surface can be formed by raised portions on a micron or
submicron scale. The height of the raised portions can range from
about 1 .mu.m to 100 .mu.m in one embodiment. The shape and height
of the raised portions forming the textured surface can vary
depending on the use and material of the probe.
[0058] In another embodiment shown in FIG. 5, the medical device is
a probe 40 having a distal end forming a tip 42 coated with a
lubricant 44 such as a crosslinked polysiloxane lubricant. In this
embodiment, only tip 42 is coated with the crosslinked lubricant.
The medical device is then coated with an outer layer 46 of an
uncrosslinked lubricant such as a water dispersible or water based
silicone lubricant. The outer layer 46 extends over the inner
lubricant coating 44 at the tip 42 and extends from the distal end
42 toward the proximal end 50 a distance sufficient to cover the
area that will come in contact with the tissue when positioned in
the insertion site. The outer lubricant layer 46 provides the
necessary lubricity to assist in the insertion of the medical
device into the tissue at the insertion site. The outer lubricant
layer 46 can be partially or substantially wiped from the surface
of the medical device upon insertion as in the previous embodiment.
Alternatively, the outer lubricant 46 can be tailored to dissolve
or disperse in the body fluids at the insertion site to form a
textured surface for contacting the tissue at the insertion site or
to expose the surface of the medical device. The resulting surface
preferably has a coefficient of friction greater than the initial
coefficient of the original lubricant coating in the contact area
of the medical device to inhibit movement and friction at the
insertion site while reducing the lubricity to prevent excessive
movement between the medical device and the tissue. The distal end
of the medical device has the crosslinked lubricant covering a
sufficient area of the device to allow some limited movement while
being worn by the patient to minimize irritation at the insertion
site while allowing removal of the device with minimal
discomfort.
[0059] A crosslinked lubricant is particularly suitable for use on
the medical device when the lubricant in intended to remain on the
surfaces of the medical device after insertion into the tissue. One
such crosslinked lubricant can be formed from a mixture of polymers
where at least one of the polymers is capable of crosslinking in
the presence of an activator. An example of a crosslinked lubricant
is formed from a mixture of a high viscosity silicone polymer that
is dissolved or diluted in a low viscosity siloxane polymer which
acts as a carrier and reactive silicone polymer which is capable of
crosslinking to form a crosslinked polymer network. Typically, the
crosslinkable polymer is an ethylenically unsaturated component. An
adhesion promoter can be added if needed to promote adhesion of the
lubricant coating to the surface of the medical device. The mixture
of the silicone polymers can be applied to the surface of the
medical device by spraying, dipping or other methods known in the
art and cured in place. The polymer mixture can be cured by a
photo-initiator to promote free radical crosslinking by exposure to
UV light. Suitable crosslinking agents include ketones such as
benzyl and benzoin and acyloins and acryoin esters. The thickness
of the coatings is generally in the range of about 50 to 500
microns. One example of a suitable crosslinked lubricant is
disclosed in U.S. Pat. Nos. 7,332,227, 6,102,898 and 5,911,711,
which are hereby incorporated by reference in their entirety.
[0060] FIGS. 6 and 7 show another embodiment of the invention where
the medical device is a cannula 52 having a cylindrical body 54, a
pointed sharp tip 56, and bore 58 for delivering fluid or removing
fluid from the patient. As shown in FIG. 7, the cannula has an
inner coating 60 of a first lubricant and a second outer coating 62
of a second lubricant. In this embodiment, the inner coating 60 is
a polymeric coating having a lubricity less than the lubricity of
the outer coating. The outer lubricant coating 62 can be an
uncrosslinked silicone polymer having a lubricity sufficient to
enable efficient insertion and penetration of the cannula. The
outer lubricant coating 62 in this embodiment is removed or
partially removed upon insertion into the tissue to expose the
surface of the inner coating 60 and the cannula 52 at the tissue
interface and provide the necessary friction to inhibit movement
between the cannula and the tissue. The inner lubricant at the tip
of the cannula can be a crosslinked silicone polymer that remains
intact on the tip which allows some movement of the tip with
reduced irritation of the tissue and provides sufficient
lubrication for extraction of the cannula with minimum pain to the
patient.
[0061] The following examples were carried out to simulate the
behavior of movement or pistoning of a medical device at an
insertion site.
EXAMPLE 1
[0062] A 31 gauge by 5 mm needle was used to demonstrate the
movement and effect of a medical device inserted in the tissue of a
patient. In this example, a needle with no lubrication was used.
The needle was used to penetrate a proprietary substrate to
simulate tissue of a patient. The needle penetrated the substrate
once followed by holding the needle in place for a fixed duration.
Thereafter, a slight pulling out and pushing in action was applied
to the needle. The pulling out and pushing in action occurred over
a small fraction of the total insertion depth and at a slow speed
compared to the speed of the initial insertion. The movement and
speed of the pulling out and pushing in action on the needle was
carried out to simulate normal movement of a probe or catheter in
the tissue of a patient over an extended period of time. The
pulling out and pushing in motion was used in the testing to
simulate what is expected to be observed in a real life use such as
a body sensor being attached to the surface of the skin of a
patient by an adhesive but that does not prevent small changes in
body or skin motion around the insertion site. The pulling out and
pushing in action was conducted multiple times to simulate the wear
time of an actual medical device. The force values generated in
this example are provided for comparative values between the
examples and do not necessarily correspond to absolute terms.
[0063] FIG. 8A is a plot of the force over multiple cycles. FIG. 8B
is a plot of the force required to insert the needle and the force
applied to the pulling out and pushing in motion over multiple
cycles and a magnified plot showing the force over 5 cycles. In
FIG. 8, PPF refers to the peak penetration force reflecting the
initial high force of insertion of the needle into the substrate
followed by the high friction force or drag force (DF) during
insertion of the needle. The subsequent pulling out and pushing in
of the needle show a similar high drag force (DF) between the
needle and the insertion site of the substrate.
EXAMPLE 2
[0064] In this example, a 31 by 5 mm needle was used as in Example
1 which was coated with a crosslinked lubricant composition. The
lubricant coated needle was inserted into the substrate. As shown
in FIG. 9A and FIG. 9B, the initial peak penetration force is
reduced, relative to that shown in FIG. 8A resulting in an easier
insertion into the substrate. The drag force is also significantly
reduced, relative to that shown in FIG. 8A and FIG. 8B suggesting
that the needle is free to move when compared to the drag force of
Example 1. The reduced drag force shown in the Figures show the
ease at which the needle can move in the substrate as a result of
slight changes in movement by a patient simulated by the substrate.
The ease of movement of the needle may be detrimental to the
performance of a sensor since it might actively promote pistoning.
The Figures also show the drag force profile and a stick slip
phenomenon that causes the force to vary during the pulling out and
pushing in of the needle in the substrate.
EXAMPLE 3
[0065] In this example, a 31 gauge by 5 mm needle was coated with a
non-curing lubricant that does not form a crosslinked network and
does not bond to the surface of the needle. FIG. 10A and FIG. 10B
demonstrates that the lubricant provides a reduced peak penetration
force and a drag force compared to an unlubricated needle relative
to that shown in FIG. 9A and FIG. 9B. FIGS. 10A and 10B when
compared with FIGS. 9A and 9B of Example 2 indicate that the
uncrosslinked lubricant has an increased peak penetration force and
drag force when compared to the needle coated with a crosslinked
lubricant of Example 2. This example proposes an intermediate
configuration where the needle pull out and push in movement is not
too hindered and not too enabled by the highly lubricious coating
of Example 2.
EXAMPLE 4
[0066] In this example, a 31 gauge by 5 mm needle as in Example 1
was used where only the tip of the needle was coated with a
crosslinked lubricant. As shown in FIG. 11A and FIG. 11B, the
lubricated tip provides a reduced peak penetration force relative
to FIGS. 9A and 9B but maintains a relatively high drag force.
EXAMPLE 5
[0067] In this example, a needle as in Example 1 was used where the
tip of the needle was coated with a crosslinked lubricant and the
body of the needle was coated with a non-crosslinked lubricant as
an overcoat layer. As shown in FIG. 12A and FIG. 12B, the
lubricated tip provides a significantly reduced peak penetration
force corresponding to an initial insertion force and maintains a
relatively low drag force. In this example, the drag force is
sufficient to inhibit free movement of the needle in the substrate
after insertion.
[0068] Each of the measurements obtained according to Examples 1-5
are overlaid in a single plot in FIG. 13. As shown in the data, the
needle in Example 5 having a crosslinked lubricant on the tip of
the needle and a non-crosslinked lubricant overlying the body of
the needle provided a low initial penetration force and a drag
resistance during the pushing and pulling of the needle such that
the drag resistance indicates a coefficient of friction of the
needle sufficient to resist movement between the needle and the
tissue at an insertion site after insertion.
[0069] As demonstrated in the examples, it has been found that a
single coating of an uncrosslinked lubricant provides sufficient
lubricity to reduce the peak penetration force (PPF) during the
initial insertion into the tissue. However, the uncrosslinked
lubricant is removed from the surface of the medical device quickly
to expose the surface of the medical device which then exhibits
high drag forces on the tissue. The high drag forces on the tissue
result in inflammation and irritation of the tissue. A highly
lubricious coating on the medical device formed from a crosslinked
lubricant retains the highly lubricious surface after insertion.
Such a highly lubricious surface allows excessive and continuous
movement at the tissue interface which also can cause irritation
and inflammation. It has been found that an outer coating of a
lubricant can provide a sufficient lubricity for insertion and
penetration of the medical device in the tissue and an inner
coating or surface texture having a lower lubricity or coefficient
of friction greater than the coefficient of friction of the outer
lubricant to provide the needed resistance to movement during
normal use and movement by the patient to inhibit irritation and
inflammation of the tissue, while providing sufficient lubricating
properties to allow removal of the medical device without excessive
pain and discomfort to the patient.
[0070] While various embodiments have been chosen to describe the
invention, it will be understood by one skilled in the art that
various changes and modifications can be made without departing
from the scope of the invention as defined in the appended
claims.
* * * * *