Note: Descriptions are shown in the official language in which they were submitted.
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TITLE: TWO STEP CATHETER LUBRICATION PROCESS
INVENTOR: JANIE C. TERRY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method and apparatus for
lubricating an over the needle catheter thereby optimizing the
catheter's insertion performance.
2. description of the Related Art
A needle catheter is a surgical device for insertion into
the tissues of a body cavity. After insertion, fluids can be
introduced or removed. The problem of effectively lubricating
catheters for ease of insertion into a patient has persisted in the
medical community.
One conventional solution for lubricating a catheter is
to apply a lubricating gel to the catheter. U.S. Patent No.
4,878,906 describes a kit for use in performing a suctioning
procedure With a suction catheter. The kit includes a foil pack or
other suitable container for holding a lubricating gel. To use the
catheter, the foil package is first torn at one edge and the gel is
squeezed onto a sterile field. The catheter tip is inserted into
the gel for lubrication. This gel is a water-soluble composition.
The use of water-soluble gels has the disadvantage that the gel
loses lubricity over time. The loss of lubricant effectiveness
during a medical procedure can cause significant discomfort to the
patient.
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U.S. Patent No. 3,556,294 describes a package for
catheters in which the distal end of the catheter is enveloped
within a flexible sleeve. Lubricant filled friable capsules are
located within the sleeve. The capsules are broken by pressure to
release the lubricant. An inert liquid silicone is used in the
capsules so as to allow the catheter to remain lubricated for the
entire procedure.
U. S. Patent Nos. 4, 720, 521 and 4, 806, 430 describes a film
forming siloxane composition having a combination of three siloxane
polymers chemically crosslinked, and a non-reactive component
dispersed therein. The composition is described as useful for
lubricating hypodermic needles, razor blades and catheters.
U.S. Patent No. 3,574,673 describes a lubricant for
cutting edges, such as razor blades. A composition of a moisture
curable amine terminated organosiloxane copolymer is coated onto
the razor blades. This composition is referred to as Dow MDX 4-
4159~'. MDX 4-4159 is a registered trademark'of Dow Corning
Corporation, Midland, Michigan.
U. S. Patent No. 4, 588, 398 describes an improved operating
surface for catheter entry through skin and venipuncture. The
catheter is formed of polyurethane. After molding the catheter,
the catheter is dipped in a lubricant having a composition of a
solvent consisting of 70 percent freon: 3o percent isopropanol
mixed with 2 percent Dow MDX 4-4159~ (by weight); and 1.75 percent
Dow 360 Silicone~. Oow 360 Silicone~ is a registered trademark of
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Dow Corning Corporation, Midland, Michigan. The lubricant has a
1,000 CTKS viscosity (by weight).
Of possible general relevance to the invention are U.S.
Patent Nos. 3,683,928: 3,726,281: and 4,140,127 which describe
assemblies for self-lubricating catheters. In these patents only
a single gel type lubricant is used.
A practical solution to the problem of lubricating a
catheter with two different lubricants in order to provide improved
insertion and shaft drag reduction is not found in the prior art.
SUMMARY OF THE INVENTION
This invention is directed to lubricants for a catheter
apparatus in which problems with conventional lubricants are
eliminated. A first lubricant is located at the tip portion of the
catheter and a second lubricant on at least that portion of the
catheter positioned behind the tip. It has now been discovered
that the application of a first lubricant on a tip of a catheter
and the application of a different second lubricant on the portion
of the catheter shaft behind the tip has outstanding properties for
ease of penetration and reduction of catheter drag forces.
The lubricant applied to the tip is preferably a solution
of polydimethylsiloxane (PMDS). Most preferably, the tip lubricant
is a solution of about 0.5% Dow 360 Silicones by weight.
Preferably, the lubricant applied to the shaft is a solution of a
moisture curable silaxane and PMDS. Most preferably, the shaft
lubricant is a solution of about 2.5% Dow 360 Silicones and abuut
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1.25% Dow MDX 4-4159~ by weight. The lubricants are applied to the
catheter during manufacture of the catheter.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a side elevational view of the catheter and
applied lubricants of the present invention.
Fig. 2 is a side elevational view of the method of
application of the shaft lubricant by spraying the shaft and the
tip with the shaft lubricant.
Fig. 3 is a side elevational view of the method of
application of the shaft lubricant by dipping the shaft and the tip
into the second lubricant.
Fig. 4 is a side elevational view of the method of
application of the shaft lubricant by spraying the portion of the
shaft positioned behind the tip with the shaft lubricant.
DETATLED DESCRIPTION OF THE INVENTION
Fig. 1 is a side elevational view of a catheter 10 which
can be used according to the present invention. Catheter 10 can be
of the type described in U.S. Patent No. 4,588,398, or manufactured
by Johnson & Johnson as OPTICAL CLEAR RADIOPAQUE (OCR) referred to
as OCR-470, or can be can be formed of any polyurethane material.
It is known that polyurethane is a difficult surface to lubricate
and that the lubricant has to be specially formulated to wet the
surface .
A tip lubricant 12 is shown applied to the catheter tip
14. The catheter tip 14 is generally defined as the first 0.25 to
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0.50 inches of the end of catheter shaft 16. A portion of the
shaft 15 is positioned behind the catheter tip 14. Preferably,
catheter shaft 16 is a hollow tubular molded polyurethane resin.
A needle 13 can be positioned below the catheter tip 14 for aiding
penetration of the catheter. Needle 13 can be lubricated with a
conventional needle lubricant.
Tip lubricants 12 useful in practice of this invention
are fluids including a silicone material. Polydimethylsiloxane
(PMDS) can be used as the silicone material.
A preferred tip lubricant 12 is a lubricant having a
solvent mixed with Dow 360 Silicone~. Representative solvents are
freon, hexane, isopropanol, alkanes, toluene and non-toxic
chlorinated or fluorinated hydrocarbons. Hexane is a preferred
solvent. It will be appreciated that other solvents which are
known in the art can be used. Preferable tip lubricants 12 for
practice of this invention are lubricants consisting of about 95.0%
to about 99.5 % hexane mixed with about 0.5% to about 5.0% Dow 360
Silicones (by weight). A most preferred lubricant consists of
99.5% hexane mixed with 0.5% Dow 360 Silicone~ (by weight). Dow
360 Silicones has an inherent high viscosity of 1,000 CTKS to about
100,000 centistokes (CTKS). Preferably, tip lubricant 12 includes
Dow 360 Silicones having a 12,500 CTKS viscosity measured at room
temperature. Room temperature is about 20°C to 25°C.
Tip lubricant 12 is applied to the catheter tip 14 by
dipping the tip into a solution of the tip lubricant 12. In the
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alternative, tip lubricant 12 can be applied by directing a spray
of the lubricant onto the tip 14.
Shaft lubricant 18 is a composition of a moisture curable
silicone. Silicone compositions when cured have the advantages of:
increased adherence of the silicone to the catheter; and, of having
the silicone being dry to the touch and thus less likely to trap
foreign material such as dust. The increased adherence of the
silicone has the advantage that the lubricant does not easily wipe
off of the catheter.
A preferred moisture curable silicone is an amine
terminated organosiloxane copolymer as described in U.S. Patent No.
3,574,673 and referred to as Dow MDX 4-4159~. Preferably, shaft
lubricant 18 is a lubricant consisting of 96.25% to about 99.0%
solvent mixed with about 1.0% to about 2.5% Dow 360 Silicone' (by
weight) and about 1.0% to about 2.5% Dow MDX 4-4159~ (by weight).
Viscosity of the shaft lubricant 18 is between 1,000 CTKS to about
100,000 CTKS. The solvent used in shaft lubricant 18 can be chosen
from the same solvents described above for use in the tip lubricant
12. A most preferred shaft lubricant 18 consists of 96.5% hexane
mixed with 2.5% Dow 360 Silicones (by weight, 12,500 CTKS) and
1.25% MDX 4-4159~ (by weight, 12,500 CTKS).
Figs. 2-4 are side elevational views of the application
of the shaft lubricant 18 in three different embodiments. Fig. 2
illustrates a first embodiment. In the first embodiment, shaft
lubricant 18 is applied over tip lubricant 12 and to the portion of
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the shaft 15. In this embodiment, shaft lubricant 18 is applied to
both the tip of the catheter 14 and the portion of the catheter
shaft 15 by spraying the total area with shaft lubricant 18. Spray
20 is applied by a conventional spraying device 22 as is known in
the art.
Fig. 3 illustrates a second embodiment. In the second
embodiment, shaft lubricant 18 is applied by dipping catheter tip
14 and the portion of the catheter shaft 15 into a solution of the
shaft lubricant 24. In the third embodiment illustrated in Fig. 4,
shaft lubricant 18 is applied only to the portion of the shaft 15
positioned behind the tip lubricant 12. Shaft lubricant 18 is
applied by spraying the portion of the shaft 15 behind the tip into
the shaft lubricant 18. Spray 26 is applied with the conWentional
spraying device 22. Spraying device 22 is adjusted to spray the
portion of the catheter shaft 15. In all of the above-described
embodiments, tip lubricant 12 and shaft lubricant 18 are applied
during manufacture of catheter 10. It will be appreciated that
other methods for applying lubricants to catheters are known in the
art.
A first experiment applied various combinations of tip
and body lubricants to a catheter. The tip was dipped into the tip
lubricant. The shaft and the tip were sprayed with the shaft
lubricant. Penetration testing was performed through a pigskin
having a thickness of about 1/16 to about 3/16 of an inch. In the
penetration testing, the film is stretched taut and the needle and
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catheter are entirely inserted through the film. Farce
measurements are taken in grams necessary to penetrate the film.
Measurements were also performed on catheter shaft drag. Catheter
shaft is defined as the force required to drag the catheter through
the punctured pigskin when inserting the catheter through the
pigskin. The results from the first experiment are summarized in
Table 1.
TABLE 1
Catheter
Run Tip Lubricant Shaft Lubricant Penetration D-raa
1 0.5% 360 2.5% 360/1.0% MDX 21834 7114
2 5.0% 360 2.5% 360/1.0% MDX 21537 7113
3 2.0% 360 2.5% 360/1.0% MDX 22026 7113
4 0.5% 360 1.0% 360/2.5% MDX 20431 7913
5 5.0% 360 1.0% 360/2.5% MDX 21731 8314
6 2.0% 360 1.0% 360/2.5% MDX 21134 8213
7 0.5% 360 2.5% 360/2.5% MDX 19237 9111
$ 5.0% 360 2.5% 360/2.5% MDX 21133 8611
9 2.0% 360 2.5% 360/2.5% MDX 21029 8311
INSYTE~ 23233 7919
(Control)
Teflon 26133 7.50+6
Jelco
(Control)
INSYTE~ is a registered trademark ickenson,
of Beckton, D
Franklin Lakes, New Jersey. Teflon~ a registered
is trademark of
Dupont,
Dover,
Delaware.
It was found that a tip lubricant having a level
low of
0.5% Dow 360 Silicone~ in freon, runs improved
4 and 7, had
catheter penetration values. Improveddrag results obtained
were
with a aft lubricant of solution Silicones
sh of about 2.5% Dow 360
and 1.0% MDX 4-4159~ runs 1, reducing
about 2 and 3. Accordingly,
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the MDX 4-4159~ concentration from about 2.5% to about 1.0%
indicates an improvement of drag values. However, at a higher MDX
4-4159x' concentration an improvement of penetration values was
obtained.
In a second experiment, a shaft lubricant of combinations
of about 0.5% to about 2.5% Dow 360 Silicones and of about 0.5% to
about 2.5% MDX 4-4159 in hexane was applied to the catheter. The
shaft and tip were sprayed with the shaft lubricant. In runs 1, 4,
5, 8, 9, 12 and 13 a tip lubricant was not applied. In runs 2, 6,
.0 ZO and 14 about 0.5% Dow 360 Silicone~ tip lubricant was applied
and in runs 3, 7, 11 and 15 about 2.0% Dow 360 Silicone~ tip
lubricant was applied. When the tip lubricant is applied the tip
was dipped into the tip lubricant.
T, B~ LE 2_
_5 T~.g
~UBRxC~INTSIibFT LUB RICANT Catheter a 1e
g1~ X360 % 360 %MDX PenetrationDraa P enetration
1 0.0 0.5 0.5 28531 11316 16029
2 0.5 0.5 0.5 27445 15926 11223
:0 3 2.0 0.5 0.5 29252 14336 13041
4 0.0 0.5 1.25 27443 11215 15136
5 0,0 0.5 2.5 29248 11915 21849
?5 6 0.5 0.5 2.5 25635 11912 10817
7 2.0 0.5 2.5 28651 12116 11620
8 0.0 1.25 1.25 30336 12411 20961
30 9 0.0 2.5 0.5 27947 12816 19568
0.5 2.5 0.5 28670 12826 117f30
11 2.0 2.5 0.5 31773 13121 14557
12 0.0 2.5 1.25 22127 11210 15640
35
13 0.0 2.5 2.5 24930 11512 16841
14 0.5 2.5 2.5 32049 12713 13634
2.0 2.5 2.5 32050 13512 14145
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The results show that run 12 having a composition of
about 2.5% Dow 360 Silicones and about 1.25% MDX 4-4159~ has the
lowest values for catheter penetration and shaft drag. The results
indicate that applying a tip lubricant of about 0.5% Daw 360
Silicone~ lowers the catheter penetration values.
A third experiment applied a tip lubricant of about 0.5%
Dow 360 Silicone~ by dipping the catheter into the solution for all
runs. Various concentrations of the shaft lubricant of from about
2.5% Dow 360 Silicone~, and about 1.25% MDX 4-4159~ to about 2.5%
.0 MDX 4-4159°' were sprayed on the catheter and the tip.
TABLE 3
:5 j~g~$ICANTSHAFT 1l, UaR~.CANT~thete~r jlg,gdle
gg,~ ,%360 % 360 %MDX Penetration Draa Penetration
1 0.0 2.5% 2.5% 16019 7911 9322
2 0.0 2.5% 2.5% 15818 798 8618
3 0.0 2.5% 2.5% 14518 769 8727
?0 4 0.0 2.5% 1.25% 14814 7211 8920
5 0.5 2.5% 1.5% 13419 6911 8418
The results indicate that reducing the concentration of
MDX 4-4159~ in the shaft lubricant improves both penetration and
?5 drag. The two step process in which the tip of a catheter is first
dipped into a solution of about 0.5% Dow 360 Silicones (12,500
CTSI~) and is then sprayed with a solution of about 2.5% Dow 360
Silicone~ (12,500 CTKS) and about 1.25% Dow MDX 4-4159 in hexane
produced improved penetration and drag values.
30 The present invention has the advantage of increasing a
catheter penetration value and reducing a catheter drag ~salue by
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applying a different tip lubricant and shaft lubricant to the
catheter. A tip lubricant of a solution of about 0.5% Dow 360
Silicone~ by weight and a shaft lubricant of a solution of about
2.5% Dow 360 Silicones by weight and about 1.25% MDX 4-4159~ by
weight results in increased performance of both drag and
penetration values.
While the invention has been described with reference to
the preferred embodiment, this description is not intended to be
limiting. It will be appreciated by those of ordinary skill in the
art that modifications may be made without departing from the
spirit and scope of the invention.
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