U.S. patent application number 11/509203 was filed with the patent office on 2007-03-29 for light-guided transluminal catheter.
This patent application is currently assigned to Children's Medical Center Corporation. Invention is credited to Farhad B. Imam.
Application Number | 20070073160 11/509203 |
Document ID | / |
Family ID | 37865266 |
Filed Date | 2007-03-29 |
United States Patent
Application |
20070073160 |
Kind Code |
A1 |
Imam; Farhad B. |
March 29, 2007 |
Light-guided transluminal catheter
Abstract
Generally, the present invention is directed to a light-guided
catheter for direct visualization of placement through the skin. An
embodiment of the invention includes a method for transcutaneous
viewing and guiding of intracorporeal catheters into a body that
comprises inserting a catheter into the body having at least one
lumen and internally illuminating the catheter with light capable
of propagating through the blood and tissue to an external viewer
outside of the body.
Inventors: |
Imam; Farhad B.; (Boston,
MA) |
Correspondence
Address: |
ALTERA LAW GROUP, LLC
6500 CITY WEST PARKWAY
SUITE 100
MINNEAPOLIS
MN
55344-7704
US
|
Assignee: |
Children's Medical Center
Corporation
Boston
MA
|
Family ID: |
37865266 |
Appl. No.: |
11/509203 |
Filed: |
August 24, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60716454 |
Sep 13, 2005 |
|
|
|
Current U.S.
Class: |
600/476 |
Current CPC
Class: |
A61B 90/39 20160201;
A61B 5/150748 20130101; A61B 2090/3945 20160201; A61B 5/15003
20130101; A61B 18/24 20130101; A61B 5/1535 20130101 |
Class at
Publication: |
600/476 |
International
Class: |
A61B 6/00 20060101
A61B006/00 |
Claims
1. A method for transcutaneous viewing and guiding of
intracorporeal catheters into a body, comprising the steps of: a)
inserting a catheter having at least one lumen, into the body; and
b) illuminating said catheter along at least a portion of its
lateral surface length with a signal which would be capable of
propagating through blood and tissue to an external viewer or
detector outside of the body, so that the viewer can detect at
least a partial length of the catheter within the body.
2. The method of claim 1 further including the step of inserting
into the lumen a source of visible illumination capable of
propagating through blood and tissue to an external viewer or
detector outside of the body.
3. The method of claim 1 wherein said internally illuminated
catheter emits light of first color and further includes the step
of inserting into the lumen a second source of illumination of a
second color different from said first color, both of said colors
being capable of propagating through blood and tissue to an
external viewer outside of the body, whereby the location of each
illumination source can be discerned from outside the body.
4. The method of claim 1 wherein the catheter is made of a material
opaque to visible light and the light emitting device extends
beyond the distal end of the catheter.
5. A method of locating non-visible intracorporeal/ blood vessels
for catheterization comprising the steps of; a. illuminating
candidate locations with light capable of inducing fluorescence
from blood constituents; and b. detecting responsive fluorescent
response from said blood constituents; and c. selecting potential
site for catheterization based upon detection of a predetermined
fluorescent signal.
6. A transcutaneously viewable catheter comprising; a. a tubular
member having an insertable end and a first channel along the
length of said catheter; b. a removable illumination source in said
channel having at least an illuminated end, said source being
configured to be extendible through said channel and beyond said
end so that when said source is inserted into the channel, the
illumination is visible outside the body, and the end thereof can
be visually located.
7. The apparatus of claim 6 wherein said tubular member is
substantially opaque to light from the illumination source; so that
when said removable source is extended beyond end of the member,
the illumination is visible outside the body.
8. The apparatus of claim 6 wherein said tubular member is
partially transparent to light emitted by said illumination source;
so that when said illumination source reaches the end of tubular
member, an observer can detect the difference in level, pattern, or
wavelength of light transmission as the illumination source exits
the tubular member.
9. The apparatus of claim 6 wherein said illumination source is
leaky and emits light along at least a portion of its length.
10. The apparatus of claim 9 wherein said illumination source emits
light of a different intensity, pattern, or wavelength at its end
than elsewhere therealong, so that it is possible to easily discern
its path and end from outside the body.
11. An apparatus for locating substantially non-visible
intracorporeal/ blood vessels for catheterization comprising; a) a
tubular member having an insertable end and a channel along the
length thereof; b) a removable illumination source insertable in
said channel having an illuminated end configured to be extendible
through said channel; c) an illumination source capable of emitting
light of a predetermined optical wavelengths to excite fluorescence
from blood constituents; d) an optical channel to receive
fluorescence from blood constituents; and e) an optical detector
coupled to the optical channel to measure fluorescence from blood
constituents.
12. The apparatus of claim 11 wherein the illumination source
comprises a low-loss fiber optic conductor.
13. The apparatus of claim 11 wherein the illumination source
comprises a light emitting diode emitting at least visible
light.
14. The apparatus of claim 11 wherein the optical channel
simultaneously delivers the illumination energy to excite
fluorescence and receives fluorescence from blood constituents.
15. The apparatus of claim 10 wherein the optical components
include a separator to separate illumination and fluorescence
signals prior to the optical detector.
16. The apparatus of claim 15 wherein the separator is a dichroic
mirror.
17. A transcutaneously viewable or detectable catheter comprising;
a. a tubular member having an insertable end b. a first channel
along the length of said catheter c. a first fiber optic having an
end and being formed within said tubular member and running
substantially the length thereof; at least a portion of said optic
being leaky; and d. a first illumination source being connectable
to said first optic to provide illumination at least along a
portion of the length of the catheter with a first predetermined
color of light; and so that the illumination is visible outside the
body.
18. The catheter of claim 17 further including second fiber optic
having an end and being insertable through said first channel and
being likewise attachable to a source of illumination, said second
optic being illuminated with a color distinguishable from the first
color which said first optic is illuminated, so that the location
of the end of said second optic can be distinguished from said
first optic.
19. The catheter of claim 18 wherein said second optic is only
leaky in a region extending from its end and a portion extending
therefrom.
20. The catheter of claim 17 further including a second fiber optic
having an end and being formed within said tubular member and
running substantially the length thereof; at least a portion of
said optic being leaky proximate its end and a portion extending
therefrom; and a second illumination source being connectable to
said second optic to provide illumination to said leaky portion,
said second source providing a illumination color different from
said the color of said first source; whereby the end of said second
optic can be visually distinguished from said first optic.
21. The catheter of claim 17 further including an elongated radio
opaque element having an end and being insertable through said
first channel; so that the location of the end of said elongated
element can be distinguished from said first optic and detected
from outside the body.
22. The catheter of claim 21 wherein said element includes a second
fiber optic along at least a portion of the element; so that the
location of said element can be detected either visually or by
radio detection.
Description
FIELD OF THE INVENTION
[0001] The present invention is directed generally to medical
devices and more particularly to a light-guided catheter with
inside-out transcutaneous illumination and visualization of
placement through the skin including a method to locate non-visible
blood vessels for catheterization.
BACKGROUND
[0002] Generally to insert a catheter into a blood vessel, the
vessel is initially identified via aspiration by a syringe with an
attached hollow needle by a technique commonly referred to as the
Seldinger technique. When blood is drawn into the syringe this
indicates that the vessel has been found. The syringe is then
disengaged from the needle and the needle lumen is occluded to
prevent a possible air embolism and/or to prevent excessive
bleeding. Thereafter, confirmation of needle placement in the vein
or artery can be assured by haemodynamic monitoring or checking for
pulsatile blood flow. Then, a thin guide wire is introduced,
typically through the syringe needle or other introducer device,
into the interior of the blood vessel. The needle/introducer device
is then withdrawn leaving the guide wire within the vessel, wherein
the guide wire projects outwardly beyond the surface of the
skin.
[0003] At this point, several options are available to a physician
for catheter placement. The simplest is to pass the catheter
directly into the blood vessel directly over the guide wire. The
guide wire is then withdrawn, leaving the catheter in position
within the vessel. Correct catheter tip placement may then be
verified by x-ray procedures. However, this technique is only
possible in cases where the catheter is of a relatively small
diameter and not significantly larger than the guide wire. If the
catheter to be inserted is significantly larger than the guide
wire, a dilator device may be first passed over the guide wire to
enlarge the insertion hole. The catheter is then introduced over
the dialator/guide wire, and the guide wire and dilator are
withdrawn.
[0004] The technique may be rather routine and straightforward in
cases where the patient's blood vessel is near the surface of the
skin and is directly visible. However, there are patients
(especially the elderly and newborns) wherein their blood vessels
are not easily visible and the initial needle puncture may default
to a hunt-and peck routine to find the elusive vessel. Even more,
once the elusive vessel is found, the insertion of the catheter is
usually a blind procedure with verification of correct catheter tip
placement only confirmed after the fact by radiographic
methods.
[0005] Given this, there is a need for a technique to visualize
and/or identify the relative location of non-visible blood vessels
for initial catheter entry and subsequent real-time visualization
while guiding the catheter for correct tip placement.
SUMMARY OF THE INVENTION
[0006] Generally, the present invention is directed to medical
devices and more particularly to a light-guided catheter with
inside-out transcutaneous illumination and visualization of
placement through the skin for the purpose of allowing real-time
visual guidance, including a method to locate non-visible blood
vessels for catheterization.
[0007] One particular embodiment of the invention is directed to a
method for transcutaneous viewing and guiding of intracorporeal
catheters into a body that comprises inserting a catheter into the
body having at least one lumen and internally illuminating the
catheter with light capable of propagating through the blood and
tissue to an external viewer outside of the body.
[0008] Another embodiment of the invention is directed to a method
for transcutaneous viewing and guiding of intracorporeal catheters
into a body that comprises inserting a catheter into the body
having at least one lumen and inserting into the lumen a source of
illumination capable of propagating through the blood and tissue to
an external viewer outside of the body.
[0009] Another embodiment of the invention is directed to a method
for transcutaneous viewing and guiding of
intracorporeal/intraarterial catheters wherein the internally
illuminated catheter emits light of a first color and further
includes the step of inserting into the catheter lumen a second
source of illumination of a second color different from the first
color, both of the colors being capable of propagating through
blood and tissue to an external viewer outside of the body, whereby
the location of each illumination source can be discerned from
outside the body.
[0010] Another embodiment of the invention is directed to a method
for transcutaneous viewing and guiding of intracorporeal/ catheters
wherein the internally illuminated catheter is made of a material
opaque to visible light and the light emitting device extends
beyond the distal end of the catheter.
[0011] Another embodiment of the invention is directed to a method
of locating non-visible intracorporeal/ blood vessels for
catheterization comprising illuminating candidate locations with
light capable of inducing fluorescence from blood constituents and
detecting fluorescent response from the blood constituents thereby
selecting the potential site for catheterization based upon
detection of a predetermined fluorescent signal.
[0012] Another embodiment of the invention is directed to a
transcutaneously viewable catheter comprising a tubular member
having an insertable end and a first channel along the length of
the catheter. The catheter has a removable illumination source in
said channel having at least an illuminated end, the source being
configured to be extendible through said channel and beyond said
end so that when the source is inserted into the channel, the
illumination is visible outside the body, and the end thereof can
be visually located.
[0013] Another embodiment of the invention is directed to a
transcutaneously viewable catheter wherein the tubular member is
substantially opaque to light from the illumination source; so that
when the removable source is extended beyond the end of the member,
the illumination is visible outside the body.
[0014] Another embodiment of the invention is directed to a
transcutaneously viewable catheter wherein the tubular member is
partially transparent to light emitted by the illumination source;
so that when the illumination source reaches the end of tubular
member, an observer can detect the difference in level or color of
light transmission as the illumination source exits the tubular
member.
[0015] Another embodiment of the invention is directed to a
transcutaneously viewable catheter wherein the illumination source
is leaky and emits light along at least a portion of its length,
whether discrete or continuous.
[0016] Another embodiment of the invention is directed to a
transcutaneously viewable catheter wherein the illumination source
emits more light at its end than elsewhere therealong, so that it
is possible to easily discern its path and end from outside the
body.
[0017] Another embodiment of the invention is directed to an
apparatus for locating substantially non-visible
intracorporeal/blood vessels for catheterization comprising a
tubular member having an insertable end and a channel along the
length thereof. The apparatus has a removable illumination source
insertable in the channel having an illuminated end configured to
be extendible through the channel. The illumination source is
capable of emitting light of predetermined optical wavelengths to
excite fluorescence from blood constituents including an optical
channel to receive fluorescence from blood constituents and an
optical detector coupled to the optical channel to measure the
fluorescence from the blood constituents. This embodiment could be
incorporated into all other embodiments for facilitation of initial
vessel identification and placement prior to catheter insertion and
final optimization of final tip placement.
[0018] Another embodiment of the invention is directed to an
apparatus for locating substantially non-visible intracorporeal/
blood vessels for catheterization wherein an appropriate
illumination source would be used, such as a low-loss fiber optic
conductor or light-emitting diode.
[0019] Another embodiment of the invention is directed to an
apparatus for locating substantially non-visible intracorporeal/
blood vessels for catheterization wherein the optical channel
simultaneously delivers the illumination energy to excite
fluorescence and receives fluorescence from blood constituents.
[0020] Another embodiment of the invention is directed to an
apparatus for locating substantially non-visible intracorporeal/
blood vessels for catheterization wherein the optical components
include a separator, such as but not limited to a dichroic mirror,
to separate illumination and fluorescence signals prior to the
optical detector.
[0021] Another embodiment of the invention is directed to a
transcutaneously viewable catheter comprising a tubular member
having an insertable end and a first channel along the length of
the catheter, with a first optic having an end and being formed
within the tubular member and running substantially the length
thereof. At least a portion of the first optic is leaky and an
illumination source is connected to the optic to provide
illumination at least along a portion of the length of the catheter
with an optimized color of light so that the illumination is
visible outside the body.
[0022] Another embodiment of the invention is directed to a
transcutaneously viewable catheter comprising a tubular member
having an insertable end and a channel along the length of the
catheter, with a first optic embedded within the tubular member and
running substantially the length thereof and a second optic
inserted into the catheter channel and running substantially the
length thereof. At least a portion of both optics are leaky and
separate illumination sources of distinguishable colors or
intensities are connected to each optic so that when both are
illuminated the location of the end of the second optic can be
distinguished from the first optic.
[0023] Another embodiment of the invention is directed to a
transcutaneously viewable catheter comprising a tubular member
having an insertable end and a channel along the length of the
catheter, with a first optic embedded within the tubular member and
running substantially the length thereof and a second optic
inserted into the catheter channel and running substantially the
length thereof. At least a portion of both optics are leaky, the
second optic being leaky only near its end, and separate
illumination sources of distinguishable colors are connected to
each optic so that when both are illuminated the location of the
end of the second optic can be distinguished from the first
optic.
[0024] Another embodiment of the invention is directed to a
transcutaneously viewable catheter comprising a tubular member
having a first and second optic embedded within the tubular member
and running along the length of the catheter. At least a portion of
both optics are leaky, the second optic being leaky proximate its
end, and separate illumination sources of distinguishable colors
are connected to each optic so that when both are illuminated the
location of the end of the second optic can be distinguished from
the first optic.
[0025] Another embodiment of the invention is directed to a
transcutaneously viewable catheter comprising a tubular member
having an insertable end and a first channel along the length of
the catheter, with a first optic having an end and being formed
within the tubular member and running substantially the length
thereof. At least a portion of the first optic is leaky and an
illumination source is connected to the optic to provide
illumination at least along a portion of the length of the catheter
with a predetermined color of light so that the illumination is
visible outside the body. The catheter further includes an
enlongated radio opaque element having an end and being insertable
through the first channel, so that the location of the end of the
elongated element can be distinguished from the first optic and
detected from outside the body.
[0026] Another embodiment of the invention is directed to a
transcutaneously viewable catheter comprising a tubular member
having a first and second optic embedded within the tubular member
and running along the length of the catheter. At least a portion of
both optics are leaky, the second optic being leaky proximate to
its end, and separate illumination sources of distinguishable
colors are connected to each optic so that when both are
illuminated the location of the end of the second optic can be
distinguished from the first optic. The catheter further includes
an enlongated radio opaque element having an end and being
insertable through the first channel. In this manner, the location
of the end of the elongated element can be detected either visually
via fluorescence using the light-emitting optic, or by radio
detection (X-ray fluoroscopy techniques) if the optic has been
removed.
[0027] The above summary of the present invention is not intended
to describe each illustrated embodiment or every implementation of
the present invention. The figures and the detailed description
which follow more particularly exemplify these embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The invention may be more completely understood in
consideration of the following detailed description of various
embodiments of the invention in connection with the accompanying
drawings, in which:
[0029] FIG. 1 shows a schematic representation of an optically
opaque multi-lumen catheter device inserted into a patient's blood
vessel with a fiber optic device inserted into a working channel of
the catheter providing inside-out transcutaneous illumination near
the distal end of the catheter.
[0030] FIG. 2 shows a schematic representation of an optically
transparent multi-lumen catheter device inserted into a patient's
blood vessel with a fiber optic device inserted into a working
channel of the catheter providing inside-out transcutaneous
illumination along the length of the catheter.
[0031] FIG. 3A shows a side-view of a multi-lumen catheter device
with a fiber optic inserted into a working channel of the catheter
wherein the catheter device is delivering optical radiation to the
patient's blood vessel and receiving a fluorescent signal back from
chemistry constituents within the patient's blood.
[0032] FIG. 3B is an enlargement of the fiber optic device depicted
in FIG. 3A, highlighting the counter propagating excitation and
fluorescent optical signals traversing the fiber optic device.
[0033] FIG. 4 is a top view (looking down) of the catheter device
shown in FIG. 3A showing the catheter device laterally displaced
from the underlying patient's blood vessel.
[0034] FIG. 5 is a top view (looking down) of the catheter device
shown in FIG. 3A showing the catheter device directly centered over
the underlying patient's blood vessel.
[0035] While the invention is amenable to various modifications and
alternative forms, specifics thereof have been shown by way of
example in the drawings and will be described in detail. It should
be understood, however, that the intention is not to limit the
invention to the particular embodiments described. On the contrary,
the intention is to cover all modifications, equivalents, and
alternatives falling within the spirit and scope of the invention
as defined by the appended claims.
DETAILED DESCRIPTION
[0036] In general, the present invention is directed to medical
devices and more particularly to a light-guided catheter for direct
visualization of placement through the skin. The catheter may be
placed intracorporeal (inside the body) by any of the
catheterization techniques known to those skilled in the art, and
the invention includes, but is not limited to intravenous,
intraarterial, or intraluminal placement of the catheter.
[0037] One embodiment of a light-guided transluminal catheter
device 100 is depicted schematically in FIG. 1. A multi-lumen
catheter 102 is shown having been inserted through the patient's
skin 104 and into the blood vessel lumen 106 over the guidewire 108
via the usual insertion techniques (e.g., the Seldinger technique
mentioned earlier). A similar catheter without initial guidewire
may also be inserted directly through the lumen of the puncturing
needle. This is commonly done in the case of peripherally-inserted
central catheters (PICC) inserted in an extremity such as the arm
or leg and threaded all the way to the heart.
[0038] Prior to insertion into the patient's blood vessel lumen 106
through blood vessel wall 107, the surgeon may insert a fiber
optical device 110 into an available working channel 112 of the
multi-lumen catheter 102. Alternatively, the fiber optic device 110
may be used in lieu of the guidewire following the Seldinger
technique described earlier. In this approach, the fiber optic
device 110 is inserted through the hypodermic needle and the
catheter 102 is introduced into the patient's blood vessel by
sliding the catheter over the fiber optic device 110. The fiber
optical device 110 may comprise a plurality of "leaky" optical
fibers or other light radiating structures which may extend from
the exposed end 114 of the catheter 102 to slightly protruding
outward from the distal end 116 of the catheter 102 into the
patient's blood vessel lumen 106. By leaky, we refer to those
optical fibers which radiate or scatter light energy radially
outward continuously along at least a portion of the length, i.e.
the lateral surface of the fiber. In the preferred embodiment,
light emitted would preferably be in the visible light range so
that special detection equipment is not required. Illuminating at
least a portion of the length of the catheter is desirable, for
example, when inserting the catheter it may be highly advantageous
to "see" the lateral surface of the catheter when navigating a bend
or curve in the patient's blood vessel, which is not uncommon when
inserting an intracardiac or "central" catheter from a peripheral
location, as in PICC (peripherally inserted central catheter)
placement at a distal extremity and threaded toward the heart. In
this configuration, the physician may get direct visual
confirmation that the catheter is proceeding smoothly "around the
bend" without complications. This should be interpreted to mean
that a portion of the lateral surface of the catheter, which will
be inserted into the body, is capable is emitting illumination.
Illumination merely at the tip of the catheter would not be
considered to be a portion along the length or lateral surface
thereof since the tip is not reasonably considered to be "a
length". Likewise, the entire length thereof should be interpreted
broadly so as to encompass less than every millimeter of the
length, but much of the length which is inserted into the body so
that the full pathway can be detected. Light emitting devices 113
may be optically coupled to the optical fibers 110 by means well
known in the art of optical communications. For example, light
output 111 from the light emitting devices 113 may be coupled into
the optical fiber 110 via a focusing lens 115 or other light
coupling components. The light emitting devices 113 may be chosen
from the list of lasers, light emitting diodes, tungsten-halogen
lamps or other suitable light sources with appropriate optical
wavelength outputs to be visible by the naked eye or an
opto-electronic detector. In the case where opto-electronic
detectors are used which may be sensitive to non-visible
wavelengths (infrared, ultraviolet, etc.) appropriate alternative
light sources and optical fibers may be utilized to generate,
guide, and ultimately detect non-visible wavelengths emanating from
the fibers.
[0039] With respect to the wavelengths of light that have worked
best with the catheters, many of them are suitable. The main
differences lie in the penetrance of immediate and adjacent
tissues, in which the red wavelengths seem to be the most effective
(.about.625-680 nm), but 532 nm (green) also works sufficiently.
This general wavelength has the advantage of minimizing the amount
of scattering and provides for more precise catheter localization
as would the red range at, for example, 5 milliwatts (mw) of
power.
[0040] Therefore, preferred embodiments might include green (532
nm) and/or red (635 nm) wavelength light sources coupled to the
optic, which in preliminary experiments in rabbits and neonatal
humans have been able to penetrate >1 cm of tissue and therefore
would be visible to the naked eye at depths of up to 1 cm below the
skin surface with relatively low light power (<5 mw).
[0041] In short, visible light is highly advantageous because no
special detection equipment is needed other than perhaps dimming of
the ambient room light, which is already routinely practiced in the
ICU environment with traditional venous transilluminators to
identify vessels for venipuncture and/or arterial puncture.
[0042] In the embodiment depicted in FIG. 1, the outer surface 118
of the multi-lumen catheter device 102 may be optically opaque so
that only optical radiation 119 emanating from that portion of the
optical fiber protruding from the distal end of the catheter 116
may propagate outward through the luminal blood 106/skin 104
regions ultimately to the surgeon's eyes 120 for direct viewing of
the in-dwelling location of the catheter tip region 116 (this
region being defined as the tip itself and a portion of the
catheter extending away from the tip so that a sufficient portion
of the catheter can be easily detected. By illuminating only the
tip, (essentially a point source) the possibility of an error in
detection or reading is increased. This is avoided by illuminating
a region adjacent the tip simultaneously. The light emitting
devices 113 may be operated continuously, intermittently, or in
pulsatile fashion to facilitate visibility through the luminal
blood 106/skin 104 regions. Given this, the physician may visually
track the location of the distal end region of the catheter 116 as
the catheter is maneuvered further upstream in the patient's blood
vessel lumen 106 towards the ultimate targeted location.
Alternatively, the physician may insert the fiber optical device
110 after the catheter 102 is initially inserted into the patient's
blood vessel lumen 106 and guide the catheter 102 by viewing the
illuminated distal tip 116 as mentioned above.
[0043] An alternative embodiment 200 of the present invention is
depicted schematically in FIG. 2. A multi-lumen catheter 202 is
shown having been inserted through the patient's skin 204 and into
the blood vessel 206 over the guidewire 208 via the usual insertion
techniques (e.g., the Seldinger technique mentioned earlier).
[0044] Prior to insertion into the patient's blood vessel 206, the
surgeon may insert a fiber optical device 210 into an available
working channel 212 of the multi-lumen catheter 202. The fiber
optical device 210 may consist of a plurality of "leaky" optical
fibers or other light radiating structures which may extend from
the exposed end 214 of the catheter 202 to slightly protruding
outward from the distal end 216 of the catheter 202 into the
patient's blood vessel 206. By leaky, we refer to those optical
fibers which radiate or scatter light energy radially outward
continuously along the length of the fiber. Light emitting devices
213 may be optically coupled to the optical fibers 210 by means
well known in the art of optical communications. The light emitting
devices 213 may be chosen from the list of lasers, light emitting
diodes, tungsten-halogen lamps or other suitable light sources with
appropriate optical wavelength outputs to be visible by the naked
eye.
[0045] In the embodiment depicted in FIG. 2, the outer surface 218
of the multi-lumen catheter device 202 may be partially,
segmentally, or entirely optically transparent so that optical
radiation 219 emanating from the optical fiber may propagate
outward along the entire length of the fiber/catheter through the
blood 206/skin 204 regions ultimately to the surgeon's eyes 220 for
direct viewing of the in-dwelling location of the catheter 202. The
outer surface 218 may also modify the intensity, scatter, or
wavelength of light passing through it such that the observer or
detector would be able to discern the portion of the optic fiber
extruded past the catheter tip from the potion lying within it.
Given this, the physician may visually track the location of the
entire length of the catheter 202 as the catheter is maneuvered
further upstream in the patient's blood vessel 206 towards the
ultimate targeted location. Alternatively, the physician may insert
the fiber optical device 210 after the catheter 202 is initially
inserted into the patient's blood vessel 206 and guide the catheter
202 by viewing the illuminated catheter as mentioned above. In an
alternative embodiment, the fiber optic device 210 may be inserted
into an available working channel 212 of the multi-lumen catheter
202 as before, however, in this case prior to patient insertion the
fiber end-face may be withdrawn a sufficient distance back into the
distal end 216 of the catheter such that only the lateral surface
218 of the catheter is illuminated. This configuration may
eliminate the possibility of the fiber end-face irritating the wall
of the patient's blood vessel as the catheter is being inserted,
while still illuminating through the lateral surface of a
translucent or otherwise non-opaque catheter, the lateral surface
218 of the catheter 202 during insertion and final placement.
[0046] In situations where the physician threading the catheter is
particularly interested in the location of the catheter tip, the
physician may utilize two individual optical fibers 210 to achieve
this result. For example, one fiber may be either be pre-loaded
into the catheter 202 flush with the distal end 216 of the catheter
202 or the fiber may be embedded in the wall of the catheter 202
terminating at the distal end 216 of the catheter 202. This fiber
may be "leaky" along its length and when coupled with a blue LED
light source 213, for example, it may illuminate the entire
sidewall of the catheter 202 with a blue tint, seen
transcutaneously. A second "non-leaky" optical fiber may be
inserted into a working lumen of the catheter 202 and may be
coupled to a green LED. As the second fiber is inserted into
catheter 202 and slightly beyond the distal end 216 of the catheter
202 the transition from blue to green seen transcutaneously may
serve as a marker identifying the location of the distal tip 216 of
the catheter 202. Of course, different color light sources than the
blue/green pair outlined above may be utilized to achieve similar
results, wherein in all cases it is preferred that the light
sources generate light visible to the naked eye.
[0047] An alternative embodiment to locate the distal tip 216 of
the catheter 202 incorporates embedding two separate optical fibers
in the wall of the catheter 202. Similar to the above embodiment,
the first optical fiber may be embedded in the wall of the catheter
202 terminating at the distal end 216 of the catheter 202. The
first fiber may be "leaky" along its length and when coupled with a
blue LED light source 213, for example, it may illuminate the
entire sidewall of the catheter 202 with a blue tint, seen
transcutaneously. A second "non-leaky" (i.e., optical energy only
radiating from the distal end) fiber may also be imbedded in the
wall of the catheter 202 terminating approximately an inch from the
distal end 216 of the catheter 202 and may be coupled to a green
LED. In this configuration, the transition from a pure blue
transcutaneous tint to a blue/green mixture may identify the
location of the distal end region 216 of the intracorporeal
catheter 202. As before, different choices for the light sources
may lead to acceptable alternative color combinations for
transcutaneous viewing such as blue/white, green/white, yellow/blue
and the like.
[0048] Another embodiment of the present invention comprises the
combination of a fiber-illuminated catheter used in tandem with a
traditional radio-opaque wire used in X-ray fluoroscopy. In this
embodiment a single or multiple lumen catheter may have the
illuminating and/or radio-opaque fiber either embedded in the wall
of the catheter or inserted in an available catheter lumen as
before. The radio-opaque wire may be inserted into a vacant
catheter lumen or inserted into the same lumen as the illuminating
fiber. The illuminating fiber itself may also be radio-opaque
(though another embodiment includes a radio-opaque fiber which will
both provide propagation of light when connected to a source of
illumination, but also be visulizable on radiographs) In this
configuration, the physician may multiplex back and forth between
the two approaches as necessary. For example, an initial entry into
the radial artery (arm) destined for the cardiac region may proceed
as follows. Initial entry and threading in the arm may be guided
directly by transcutaneous viewing of the fiber-illuminated
catheter as outlined before. Upon entry into the chest cavity
region, the physician may choose to switch to standard X-ray
fluoroscopy when and if the visibility of the fiber-illumination
becomes too faint to discern.
[0049] Another embodiment of the present invention encompasses a
dual-purpose function of the illuminating fiber. In this embodiment
the illuminating optical fiber is inserted into an available lumen
and illuminates the distal end of the catheter as previously
outlined. In addition the fiber may have optically excited chemical
sensors attached to the distal end of the fiber. For example,
fluorescent dyes sensitive to the dissolved oxygen in blood
(sometimes referred to as the partial pressure of oxygen in blood
and designated as pO.sub.2) are well known and historically have
been encapsulated in a polymer membrane attached to the distal end
of the sensing fiber. Similarly, additional fluorescent dyes have
been demonstrated to respond to the dissolved carbon dioxide in
blood (pCO.sub.2) as well as the acidity (pH) of blood. The trio
above, pO2, pCO2, and blood pH are commonly referred to as a "blood
gas" measurement in a hospital setting. A detailed explanation of
the mechanism involved for optically sensing "blood gases" by way
of fluorescent chemical sensors/dyes attached to the distal end of
an optical fiber can be found in U.S. Pat. No. 5,672,515 titled
"Simultaneous Dual Excitation Single Emission Fluorescent Sensing
Method For pH and pCO.sub.2" which is incorporated herein by
reference. The additional ability to measure one or more of the
"blood gases" while simultaneously viewing the illuminated catheter
transcutaneously may allow the physician sufficient information to
ascertain whether the catheter has been threaded into arterial or
mixed venous blood, given that typical blood gas measurements for
venous blood is discernibly different than arterial values.
[0050] The above embodiments may also be particularly useful in the
placement of peripherally-inserted central catheters (commonly
referred to as PICC lines), as well as umbilical artery and vein
catheters used in the neonatal intensive care units. PICC lines are
commonly introduced into the patient's arm or leg through the lumen
of the puncturing needle and threaded all the way to the patient's
heart. The PICC lines are subject to being misrouted when inserted
and guided (threaded) blindly, and with direct transcutaneous
viewing of the catheter while threading, this may be alleviated.
The direct transcutaneous viewing of the catheter while threading
may be ideal for newborn infants with inherently thin skin, and may
also be applicable to a large segment of the adult population,
especially the elderly.
[0051] An alternative embodiment of the present invention is
depicted schematically in FIGS. 3A and 3B. FIG. 3A shows a catheter
300 configured to function as an artery or vein-finder device to
optically locate blood vessels which may not be visible directly by
the unaided eye. A side view of a multi-lumen catheter 302 is shown
in contact with a patient's skin 304 directly over the patient's
blood vessel 306. An optical fiber 310 has been inserted into an
available working channel 312 of the catheter 302. The optical
fiber 310 may be similar to those currently used in optical
communications (i.e., "non-leaky" in contrast to the "leaky" fibers
depicted in FIGS. 1 and 2) with the ability to waveguide light over
long distance with minimal loss out the lateral surface. Light
emitting devices 313 may be optically coupled to the optical fibers
310 by means well known in the art of optical communications. The
light emitting devices 313 may be chosen from the list of lasers,
light emitting diodes, tungsten-halogen lamps or other suitable
light sources with appropriate optical wavelength outputs to excite
optical fluorescence from chemistries in the underlying blood
vessel. In this configuration, the catheter 302 with inserted
optics to excite and receive fluorescent signals from chemistries
in the underlying blood vessel, may serve as an artery/vein finder
to identify the correct location for the initial needle stick
(first step in Seldinger technique or in PICC placement) to
facilitate the process of eventually placing the catheter
in-dwelling. A detailed explanation of the optical technique is
described below.
[0052] Naturally occurring chemistries in human blood are well
known to fluoresce when excited (illuminated) at a particular
wavelength corresponding to the absorption band of that chemistry.
During the subsequent fluorescence process (which usually occurs on
the order of a few nanoseconds after absorbing the illuminating
optical energy), the molecule responds by emitting optical energy
at a longer wavelength (i.e., lower energy state) than the
exciting/illuminating energy. For example, blood constituents
bilirubin and carotenoid chromophores are known to fluoresce in the
spectral region near 450 nanometers when optically excited
(illuminated) at 340 nanometers. Fluorescence form these molecules
may be used to locate the position of underlying blood vessels as
follows. The light source 313 in FIG. 3A may be chosen to emit
optical radiation 311 near 340 nanometers (corresponding to the
absorption band of bilirubin for example) which may be coupled into
optical fiber 310 which guides the optical radiation 311 to the
patient's skin surface 304. The optical radiation 311 may penetrate
through the patient's skin 304, traverse the blood vessel wall,
enter the patient's blood stream and eventually interact (be
absorbed by) a bilirubin molecule 314 present in the patient's
blood stream. Thereafter, the bilirubin molecule 314 may re-radiate
a fluorescent optical signal 316 (see the expanded view of the
fiber 310 shown in FIG. 3B), a portion of which may be coupled back
into the optical fiber 310 and guided back toward the light source
313. The returning fluorescent signal 316 may be reflected by
partial mirror 318 to optical detector 320 which may have optical
filters embedded to only respond to the 340 nanometer signal
indicative of bilirubin/blood fluorescence. In this configuration,
the optical detector 320 would receive the maximum fluorescent
signal back from the bilirubin molecule 314, when the catheter
302/fiber 310 device is directly placed over the underlying blood
vessel 306.
[0053] For example, FIG. 4 shows a top view (looking down on the
device depicted in FIG. 3) of the catheter 402 depicting the fiber
410 inserted in the working channel on the right hand side of the
catheter 402. The catheter is shown displaced vertically, i.e.,
off-set from directly over the underlying blood vessel 406, and as
such the fluorescent signal 316 (from FIG. 3) capture by the
optical fiber 410 will be relatively small. However, when the
catheter is translated down directly over the blood vessel (see
FIG. 5), the catheter 502 can be manually positioned back-and-forth
until a maximum fluorescent signal 316 (FIG. 3) is detected by the
optical detector 320 signifying the blood vessel 506 has been
located. This process can be repeated at several adjacent points to
delineate the course of the vessel subcutaneously and further aid
with correct insertion.
[0054] As noted above, the present invention is directed generally
to medical devices and more particularly to a light-guided catheter
with inside-out transcutaneous illumination and visualization of
placement through the skin including a method to locate non-visible
blood vessels for catheterization.
[0055] The present invention should not be considered limited to
the particular examples described above, but rather should be
understood to cover all aspects of the invention as fairly set out
in the attached claims. Various modifications, equivalent
processes, as well as numerous structures to which the present
invention may be applicable will be readily apparent to those of
skill in the art to which the present invention is directed upon
review of the present specification. The claims are intended to
cover such modifications and devices.
* * * * *