U.S. patent application number 12/823005 was filed with the patent office on 2010-11-25 for needle insertion systems and methods.
Invention is credited to Michael Dean Gray, Francois Guillot, James W. Larsen, Peter H. Rogers, David H. Trivett.
Application Number | 20100298702 12/823005 |
Document ID | / |
Family ID | 34102826 |
Filed Date | 2010-11-25 |
United States Patent
Application |
20100298702 |
Kind Code |
A1 |
Rogers; Peter H. ; et
al. |
November 25, 2010 |
NEEDLE INSERTION SYSTEMS AND METHODS
Abstract
Embodiments of a needle insertion system and method are
disclosed. One method embodiment includes transmitting a sound beam
along an axis to contact a blood vessel; receiving the reflected
sound beam from the blood vessel; processing the reflected sound
beam to detect the location of the blood vessel; and, responsive to
the detection, receiving a needle in a guideway that is oriented
parallel to the axis.
Inventors: |
Rogers; Peter H.; (Atlanta,
GA) ; Trivett; David H.; (Atlanta, GA) ;
Guillot; Francois; (Atlanta, GA) ; Gray; Michael
Dean; (Atlanta, GA) ; Larsen; James W.;
(Suwanee, GA) |
Correspondence
Address: |
THOMAS, KAYDEN, HORSTEMEYER & RISLEY, LLP
600 GALLERIA PARKWAY, S.E., STE 1500
ATLANTA
GA
30339-5994
US
|
Family ID: |
34102826 |
Appl. No.: |
12/823005 |
Filed: |
June 24, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10897663 |
Jul 22, 2004 |
7766839 |
|
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12823005 |
|
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|
|
60489125 |
Jul 22, 2003 |
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Current U.S.
Class: |
600/439 |
Current CPC
Class: |
A61B 8/06 20130101; A61B
8/0833 20130101; A61B 8/4281 20130101; A61B 2017/3413 20130101;
A61B 8/085 20130101; A61B 5/489 20130101 |
Class at
Publication: |
600/439 |
International
Class: |
A61B 8/13 20060101
A61B008/13 |
Claims
1. A needle insertion method, comprising: transmitting a sound beam
along an axis to contact a blood vessel; receiving the reflected
sound beam from the blood vessel; processing the reflected sound
beam to detect the location of the blood vessel; and responsive to
the detection, receiving a needle in a guideway that is oriented
parallel to the axis, wherein receiving a needle in a guideway that
is oriented parallel to the axis includes receiving the needle in
the guideway that is oriented coincident with the axis.
2. A needle insertion method, comprising: transmitting a sound beam
along a first axis to contact a blood vessel; receiving a reflected
sound beam reflected from the blood vessel along the first axis;
processing the reflected sound beam to detect the location of the
blood vessel; and responsive to the detection, receiving a needle
in a guideway that is oriented along a second axis that enables the
needle to intersect the first axis in proximity to the blood
vessel.
3. The method of claim 2, wherein transmitting includes
transmitting a pulsed ultrasonic beam focused within the body to a
diameter of approximately 1 millimeter.
4. The method of claim 2, further including providing feedback to a
user in response to the detection.
5. The method of claim 4, wherein providing feedback includes
providing the feedback at least until the needle contacts the blood
vessel.
6. The method of claim 2, further including providing at least one
of an audible sound, a visual display signal, and a tactile signal
to a user in response to the detection.
7. The method of claim 2, wherein receiving a needle in a guideway
includes receiving the needle along the second axis that has a
depth-dependent offset relative to the first axis.
8. The method of claim 2, wherein receiving a needle in a guideway
further includes contacting the blood vessel with the needle
proximally to where the sound beam was reflected from the blood
vessel.
9. A needle insertion system, comprising: a transducer assembly
configured to radiate a sound beam along a first axis and detect a
blood vessel responsive to receiving a reflected sound beam; and a
coupler that is configured to reflect the sound beam along a second
axis to and from the blood vessel, the coupler configured with a
guideway that is oriented parallel to the second axis, wherein the
guideway is oriented coincidentally with the second axis.
10. A needle insertion system, comprising: a transducer assembly
configured to radiate a sound beam along a first axis and detect a
blood vessel responsive to receiving a reflected sound beam; and a
coupler that is configured to reflect the sound beam along a second
axis to and from the blood vessel, the coupler configured with a
guideway that is oriented along a third axis that enables the
needle to intersect the second axis in proximity to the blood
vessel.
11. The system of claim 10, wherein the transducer assembly
includes a transducer set back a defined distance from a skin
surface on which the coupler rests, the transducer configured to
radiate a pulsed ultrasonic beam focused within the body to
approximately 1 mm in diameter.
12. The system of claim 10, wherein the transducer assembly
includes an output module that is configured to provide at least
one of an audible sound, a visual display signal, and a tactile
signal to a user in response to the detection of the blood
vessel.
13. The system of claim 10, wherein the guideway is configured to
receive the needle along the third axis that has a depth dependent
offset relative to the second axis.
14. The system of claim 10, wherein the guideway is receptive to a
needle that can be advanced in a direction oriented along the third
axis to contact the blood vessel in a location that is proximal to
where the sound beam intersects the third axis.
15. The system of claim 10, wherein the transducer assembly
includes at least one of a switch, transmitter electronics,
receiver electronics, an oscillator, a power amplifier, a pulse
generator, and a processor.
16. The system of claim 10, wherein the coupler includes a chamber
that contains a coupling material.
17. The system of claim 10, wherein the coupler includes a
reflective portion that reflects the sound beam from the transducer
assembly through a window to the blood vessel, and from the blood
vessel through the window to the transducer portion.
18. The system of claim 10, wherein the coupler is at least one of
attachable and detachable from the transducer assembly.
19. The system of claim 10, wherein the coupler is capable of
disassembly.
20. The system of claim 10, wherein the guideway is configured with
a slot that enables separation of the coupler and the needle.
21. A coupler that acts as an interface between a needle and a skin
surface through which the needle is to advance to contact a blood
vessel, the coupler comprising: means for receiving a reflected
sound beam along a first axis; and means for receiving a needle
along an axis that is parallel to the first axis, wherein the means
for receiving a needle is oriented coincidentally with the first
axis.
22. A coupler that acts as an interface between a needle and a skin
surface through which the needle is to advance to contact a blood
vessel, the coupler comprising: means for reflecting a transmitted
sound beam along a first axis and a reflected sound beam reflected
from a blood vessel along the first axis; and means for receiving a
needle along a second axis that is oriented to enable the needle to
intersect the first axis in proximity to a blood vessel in which
the needle is to be inserted.
23. The coupler of claim 22, wherein the means for receiving a
needle is a guideway.
24. The coupler of claim 23, wherein the guideway is slotted.
25. The coupler of claim 22, wherein the means for receiving a
reflected sound beam includes means for receiving a transmitted
sound beam along a third axis.
26. The coupler of claim 25, wherein the means for receiving a
reflected sound beam includes a chamber configured to contain a
coupling material, a reflective portion, a window, and a transducer
assembly attachment means.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This is a divisional application of U.S. patent application
Ser. No. 10/897,663 filed Jul. 22, 2004 and entitled, "Needle
Insertion Systems and Methods," which claims the priority benefit
of U.S. Provisional Application No. 60/489,125 entitled, "A Device
For Locating Veins and Aligning and Inserting Intravenous Catheters
and Blood Drawing Needles Therein," filed Jul. 22, 2003, each of
which is entirely incorporated herein by reference.
TECHNICAL FIELD
[0002] The present disclosure is generally related to the medical
field, and, more particularly, is related to systems and methods
for locating veins and other blood vessels and inserting needles
and catheters therein.
BACKGROUND
[0003] In the medical field, a common procedure performed by
emergency medical technicians, phlebotimists, nurses, doctors, and
other medical field personnel is locating veins and inserting
intravenous (IV) tubes (e.g., catheters) and blood drawing needles
therein. One problem that is often encountered when administrating
an IV or drawing blood is that it is often difficult for the
medical person to locate a vein. This problem is particularly
pronounced with obese or pediatric patients, or when conditions are
less than favorable, for example on a battlefield or at an accident
scene. Various methods and devices have been devised to help a user
to locate a vein that would be otherwise difficult to locate.
[0004] One popular method for locating a vein is the Doppler sonar
method. In this method, a transmitter (or transceiver) provides a
high frequency sound signal that is transmitted through the surface
of a patient's skin in an effort to locate a vein. Although sound
will be scattered by all tissues, for the blood flowing through a
vein, the signal will be Doppler shifted due to the motion of the
blood. If the velocity of the blood is v, the received signal
(received at the transducer of a transceiver or receiver) is
shifted in frequency as provided in Equation 1 below:
.DELTA. f = 2 f v c cos .theta. Eq . 1 ##EQU00001##
where f is the transmitted frequency (e.g., 10 Mega-Hertz (MHz)), c
is the speed of sound in the tissue (approximately 1500 meters per
second (m/sec)) and .theta. is the angle between the flow velocity
direction and the sound beam axis. For a typical vein, the flow
velocity is of the order of 10 cm/sec. If .theta. is, for example,
30.degree., the frequency shift will be 667 Hz. Such shifts can be
detected by "beating" the received signal against the transmitted
signal. The presence of an audio frequency beat signal in the
output (in this case at 667 Hz) indicates a Doppler shift, and
hence that the beam is intersecting a blood vessel such as an
artery or vein. Since arterial flow is away from the heart and
venous flow is towards the heart, the distinction between arteries
and veins is made by determining whether the Doppler shift is
positive or negative. Both the size of the Doppler shift and the
strength of the Doppler shifted signals are helpful in selecting
the most suitable vein since a larger vein has higher flow
velocities in addition to being a better scatterer.
[0005] Although the technology used to locate a vein has improved,
the methods used to insert a needle quickly and accurately using a
hand-held device and at a moderate cost could benefit from further
development.
SUMMARY
[0006] Preferred embodiments of needle insertion systems and
methods are disclosed. One method embodiment, among others, can be
generally described by the following steps: transmitting a sound
beam along an axis to contact a blood vessel; receiving the
reflected sound beam from the blood vessel; processing the
reflected sound beam to detect the location of the blood vessel;
and, responsive to the detection, receiving a needle in a guideway
that is oriented parallel to the axis.
[0007] Another embodiment of a needle insertion method, among
others, can generally be described by the following steps:
transmitting a sound beam along a first axis to contact a blood
vessel; receiving a reflected sound beam reflected from the blood
vessel along the first axis; processing the reflected sound beam to
detect the location of the blood vessel; and, responsive to the
detection, receiving a needle in a guideway that is oriented along
a second axis that enables the needle to intersect the first axis
in proximity to the blood vessel.
[0008] A needle insertion system embodiment, among others, can
include a transducer assembly configured to radiate a sound beam
along a first axis and detect a blood vessel responsive to
receiving a reflected sound beam; and a coupler that is configured
to reflect the sound beam along a second axis to and from the blood
vessel, the coupler configured with a guideway that is oriented
parallel to the second axis.
[0009] Another needle insertion system, among others, can include a
transducer assembly configured to radiate a sound beam along a
first axis and detect a blood vessel responsive to receiving a
reflected sound beam; and a coupler that is configured to reflect
the sound beam along a second axis to and from the blood vessel,
the coupler configured with a guideway that is oriented along a
third axis that enables the needle to intersect the second axis in
proximity to the blood vessel.
[0010] The preferred embodiments also include a coupler that acts
as an interface between a needle and a skin surface through which
the needle is to advance to contact a blood vessel. In one
embodiment, among others, a coupler can include means for receiving
a reflected sound beam along a first axis; and means for receiving
a needle along an axis that is parallel to the first axis.
[0011] Another embodiment of a coupler, among others, can include
means for reflecting a transmitted sound beam along a first axis
and a reflected sound beam reflected from a blood vessel along the
first axis; and means for receiving a needle along a second axis
that is oriented to enable the needle to intersect the first axis
in proximity to a blood vessel in which the needle is to be
inserted.
[0012] Other systems, methods, features, and advantages of the
disclosure will be or become apparent to one with skill in the art
upon examination of the following drawings and detailed
description. It is intended that all such additional systems,
methods, features, and advantages be included within this
description, and be within the scope of the disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The components in the drawings are not necessarily to scale,
emphasis instead being placed upon clearly illustrating the
principles of the disclosed systems and methods. Moreover, in the
drawings, like reference numerals designate corresponding parts
throughout the several views.
[0014] FIG. 1 is a schematic diagram that illustrates an embodiment
of a needle insertion system.
[0015] FIG. 2 is a block diagram that illustrates an embodiment of
a transducer assembly of the needle insertion system shown in FIG.
1.
[0016] FIG. 3 is a side-view cut-away that illustrates an
embodiment of a coupler of the needle insertion system shown in
FIG. 1.
[0017] FIG. 4 is a schematic diagram of a coupler embodiment
similar to that shown in FIG. 3 that illustrates application of a
sound beam and receiving a needle along an axis that is parallel to
and offset from a sound beam axis.
[0018] FIG. 5 is a schematic diagram of another coupler embodiment
similar to that shown in FIG. 3 that illustrates application of a
sound beam and receiving a needle along an axis that has a depth
dependent offset relative to a sound beam axis.
[0019] FIG. 6 is a front-view schematic diagram of the needle
insertion system shown in FIG. 1 that illustrates traversing the
skin surface to obtain a strong signal that indicates location of a
suitable vein and insertion location along the vein.
[0020] FIG. 7A is a schematic diagram that illustrates an
embodiment of a needle insertion system.
[0021] FIG. 7B is a side-view cut-away of an embodiment of a
coupler of the needle insertion system shown in FIG. 7A.
[0022] FIG. 8 is a flow diagram that illustrates one needle
insertion method embodiment corresponding to the embodiment shown
in FIG. 4.
[0023] FIG. 9 is a flow diagram that illustrates one needle
insertion method embodiment corresponding to the embodiment shown
in FIG. 5.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] Disclosed herein are various embodiments of a needle
insertion system and method. A needle insertion system assists a
user (e.g., a skilled medical professional such as a nurse, or an
unskilled person for do-it-yourself medical kits) in locating a
vein, for example, or artery, and inserting an intravenous (IV)
tube, catheter, and/or blood drawing needle therein. In one
embodiment, a needle insertion system is disclosed as comprising a
handheld device having a transducer assembly and a coupler. The
transducer assembly includes a focused ultrasonic transducer that
produces a narrow sound beam with a focal region (e.g., the focal
region in one embodiment having a diameter of less than or equal to
approximately 1 millimeter (mm), approximately 2.5 centimeters (cm)
in length, and whose center is approximately located 5 cm from the
transducer face). The sound beam is preferably generated as a
pulsed beam having a frequency of approximately 10 Mega-Hertz
(MHz). The transducer, operating in one embodiment in a
transmit/receive mode, detects a vein by functioning as a pulsed
Doppler blood flow detector.
[0025] The coupler is configured to guide or direct a needle into a
vein quickly and easily, and, preferably, to detach from the needle
quickly and easily. In principle, the coupler portion works by
aligning the axis of a needle relative to the axis of the sound
beam radiated from the transducer assembly. If the beam is known to
intersect a vein (using Doppler sonar), then advancing the needle
in a path provided integral to or adjacent to the coupler along the
beam axis, parallel to the beam axis at a slight offset, or offset
in a depth dependent manner to intersect the beam axis, results in
the needle entering the vein.
[0026] Although described in the context of locating a vein and
inserting a needle therein, it would be understood by those having
ordinary skill in the art that the principles disclosed in this
disclosure can also apply to the location of other blood-carrying
vessels. Further, although described using a needle, similar
principles apply to the insertion of other objects such as a
catheter, tube, or shunt, and thus are considered to be within the
scope of the preferred embodiments.
[0027] In the description that follows, a needle insertion system
embodiment is described in FIG. 1, and the various components that
comprise the same is described with respect to FIGS. 2-4. An
additional embodiment of a coupler for the needle insertion system
described in FIG. 1 is illustrated in FIG. 5. FIG. 6 illustrates a
method to elicit an optimal feedback signal indicating whether or
when the center of a vein has been located. FIGS. 7A and 7B
illustrate another embodiment of a needle insertion system and its
corresponding components. Finally, FIGS. 8 and 9 illustrates
various needle insertion method embodiments.
[0028] FIG. 1 is a schematic diagram that illustrates an embodiment
of a needle insertion system. The needle insertion system 100
includes a coupler 102 and a transducer assembly 104. The coupler
102 includes a guideway 108, in which a needle 110 can be inserted
and advanced along the guideway 108 and through the skin surface
112 to puncture a vein 114 located in a body 106 (for blood drawing
and catheter insertion, the body site of interest will often be an
arm, but the needle insertion system can be used in other locations
of the body). Although the guideway 108 can be configured as a
channel that runs through the body of the coupler 102, preferably
the guideway 108 is configured as a channel that runs along the
bottom, preferably angled surface of the coupler 102. The
transducer assembly 104 can be rotatably attached and detached from
the coupler 102, and/or slidably detached and re-attached in other
embodiments according to well-known attachment/detachment
mechanisms. Still in other embodiments, the transducer assembly 104
and the coupler 102 can be fixably attached or the two components
can be molded as a single component. The needle 110 can be packaged
with the coupler 102, for example disposed in the guideway 108 as
part of the entire coupler 102, or available separately from the
coupler 102.
[0029] FIG. 2 is a block diagram that illustrates an embodiment of
a transducer assembly 104 of the needle insertion system 100 shown
in FIG. 1. The transducer assembly 104 includes a transducer module
202, a switch module 204, a transmitter module 206, a receiver
module 208, an oscillator and processing module 210, and an output
module 212. One or more of the modules can be configured in
hardware, software, or a combination of hardware and software. The
transducer assembly 104 can be battery powered (not shown) and/or
powered externally through use of a cord or other mechanism for
connecting to an external power source.
[0030] The transducer module 202 preferably radiates a pulsed
Doppler sound field which, in one embodiment, focuses to a beam of
approximately 1 mm in diameter over a length of approximately 2.5
cm, as generated from the transmit electronics described below. The
1 mm diameter sound beam is smaller or comparable in diameter to a
vein from which it is suitable to draw blood. The transducer module
202 includes a transducer element (not shown) that can be
configured to radiate beams of greater or smaller diameter
depending on the application, by adjusting the frequency. The
transducer module 202 is also configured to receive a reflected
sound beam, which it converts to a signal(s) for processing by the
receive electronics described below.
[0031] The oscillator and processing module 210, in cooperation
with the transmitter module 206, generate the pulses at a frequency
of approximately 10 MHz, although sound beams of other frequencies
can be generated depending on the application. The pulsed mode is
preferably implemented in both transmit and receive modes. The
receiver module 208 includes receive and processing electronics to
receive the reflected signal and determine the presence or absence
of a Doppler shift. If a Doppler shift is detected, an audible
sound, tactile sensation (e.g., vibration), and/or visual display
is activated via the output module 212. For example, an audible
sound may be activated and may be adjustable based on the
surrounding environment (e.g., loud enough to hear over sirens,
etc.). As another example, a graphics user interface may be
presented on the package of the transducer assembly 104 and which
may show an arrow(s) indicating the direction of movement a user
needs to take along a person's body to locate a vein or to optimize
the signal strength (and thus center the needle on the vein). The
switch module 204 provides functionality for switching between
receive and transmit functionality. Note that the use of pulsed
Doppler may also enable estimation of the depth of the vein from
the pulse transit time. Further, the electronics of the transducer
assembly 104 are well known to those having ordinary skill in the
art, and thus further explanation of each component will be omitted
for brevity.
[0032] The transducer assembly 104, when detachable from the
coupler 102, does not have to be sterilizable. As a corollary to
the detachable/attachable feature, the transducer assembly 104 is
reusable with a plurality of different couplers 102.
[0033] Note that in some embodiments, two transducers may be used
(a transmit and receive transducer) and the switch omitted.
[0034] FIG. 3 is a side-view cut-away that illustrates an
embodiment of a coupler of the needle insertion system 100 shown in
FIG. 1. The coupler 102 comprises a coupling portion 302 and a
reflective portion 304. In one embodiment, the coupler 102 may be
disposable, and included with the needle 110 in a plastic package
(not shown) designed to maintain the sterility of the coupler 102
and the needle 110. The coupling portion 302 is preferably made of
a plastic material, although other materials may be used. The
coupling portion 302 comprises a chamber 306 that is preferably
cylindrical in configuration. The chamber 306 contains a coupling
material (not shown). The coupling material may include water,
ultrasonic gel, solid rubber couplant, among other coupling
material suitable for propagating the sound beam. The coupling
portion 302 also includes a window 308 which allows the transmitted
sound beam to radiate into the body 106 (FIG. 1) and allows the
reflected sound beam to radiate back into the coupling portion 302.
The window 308 may be comprised of a thin (e.g., approximately 25
microns to 250 microns thick) plastic material. The coupling
portion 302 further includes a housing portion 310, which receives
a transducer element (not shown) of the transducer module 202 (FIG.
2) when the coupling portion 302 is attached to the transducer
assembly 104. The coupling portion also include a tube 312. The
tube 312 serves as a conduit to enable filling the coupler with a
coupling material, such as water. In some implementations, an
ultrasonic coupling gel (not shown) may be applied to the outside
surface of the coupler 102 (i.e., the surface contacting the skin
surface 112).
[0035] The reflective portion 304 is attached to the coupling
portion 302, for example using an adhesive, through the use of
screws, or other fastening mechanisms known to those having
ordinary skill in the art. The reflective portion 304 preferably
has a flat reflecting surface (reflecting the sound beam) and is
preferably comprised of a metallic material, such as stainless
steel, although other reflective material, or a combination of
reflective and non-reflective material, may be used. The reflective
portion 304 redirects the sound beam received from a transducer
element, or the reflected sound beam received from the located
vein, at a defined angle. The reflective portion includes a
guideway 108 that has a defined angle with respect to the skin
surface 112 (FIG. 1), and is used to guide a needle along a
predetermined orientation. In one embodiment, the guideway 108 is
configured to provide a predetermined offset between the sound beam
and the needle. The offset can be made depth-dependent or
depth-independent by modifying the attachment angle (i.e., the
angle between the guideway 108 and the horizontal surface of the
coupler 102, such as .beta. in FIG. 4 described below) with respect
to the skin surface 112.
[0036] In one embodiment, the guideway 108 is made of a short,
flexible tube attached to (adjacent) the reflective portion 304
(e.g., running along the bottom, angled surface of the reflective
portion 304). The guideway 108 is preferably made of a plastic
material, and can be attached using an adhesive or other fastening
mechanisms known to those having ordinary skill in the art. A slot
(not shown) is provided at the bottom of the guideway 108 running
along the length of the guideway to enable a user to disengage the
coupler 102 from a needle once the vein is punctured. In some
embodiments, the slot can be omitted and the coupler 102 can be
disengaged from the needle by cutting the guideway 108. In some
embodiments, the slot can be omitted based on applications where
disengagement from the needle is not needed. The guideway 108 has a
diameter that is large enough to allow the needle to be advanced
through it, yet small enough to hold the needle firmly. In some
embodiment, a guideway of similar features can be configured as a
channel bored within the body of the reflective portion 304.
[0037] FIG. 4 is a schematic diagram of a coupler embodiment,
coupler 102a, similar to that shown in FIG. 3, and that illustrates
application of a sound beam and receiving a needle along an axis
that is parallel to and offset from a sound beam axis. As shown, a
transducer element 402 of the transducer assembly 104 (FIG. 1) is
disposed conformably (although any well-known attachment/detachment
mechanisms may be employed) in the housing portion 310 and secured
enough to assure proper alignment between the transducer assembly
104 and the coupler 102a. In one embodiment, the transducer element
402 has a concave surface 404 to provide a focused sound beam. The
focused beam could also be achieved using an acoustic lens. The
transducer element 402 is disposed at a distance (represented by
the line labeled "A" in FIG. 4) of approximately 4 cm from the
location 406 on the reflective surface on which a sound beam 408
(shown herein as the centerline of the beam, with the understanding
that a larger sound profile is preferably radiated) impinges to the
point on the convex surface 404 farthest from said location 406.
This 4 cm distance enables a 1 mm diameter sound beam focal region
to begin at the skin surface. Note that this dimension "A" may vary
in some embodiments, depending on the characteristics of the sound
beam from the focused transducer element 402. "A" can be determined
mathematically according to known formulas, and/or determined (or
verified) experimentally. Thus, the transducer element 402 is
disposed in the housing portion 310 at a suitable distance to
accommodate a focal length of approximately 5 cm, in such a way
that the focal region begins at the surface of the skin 112, which
enables detection of a vein along a longer range. For example,
experimentation and mathematical analysis have indicated that the
focal region for a sound field produced by a 1 centimeter (cm)
diameter, 10 MHz transducer with a focal length of 5 cm is
ellipsoidal, about 1 mm in diameter, and more than 2 cm long. In
other words, there exists a "beam-like" quality of the sound field
within .+-.1 cm of the focal point.
[0038] The sound beam 408 is radiated in the chamber 306 along an
axis that is coincident with a first axis 410. The chamber 306
includes a coupling material (not shown) that provides an
appropriate low loss impedance matched propagation medium for the
sound beam 408 when entering the interior of the body 106 and
returning from the interior of the body 106.
[0039] The sound beam 408 impinges on the reflective portion 304a
at location 406 and is reflected along an axis coincident with a
second axis 412. In one embodiment, the angle .alpha. between the
reflected sound beam along the second axis 412 and the skin surface
112 is approximately 30.degree., although other angles may be used.
The reflected sound beam 408 is transmitted through the skin
surface 112 and impinges on the vein 114, and then at least a
portion of the beam is reflected back to the transducer element 402
along the second axis 412, and then the first axis 410 after
reflection at 406 of the reflective portion 304a. The transducer
element 402 converts the received sound beam 408 to an electronic
signal that is processed in the receive electronics (e.g., 208, 210
of FIG. 2) of the transducer assembly 104 to elicit a feedback
response by the output module 212 (FIG. 2). A feedback response
provides an indication that a vein has been located, and in some
embodiments, an indication of the signal strength corresponding to
whether the vein has been located at a position offset from the
centerline of the vein (where blood flow may be slower) or at the
centerline (where blood flow is greatest).
[0040] If the vein 114 is located and the signal strength indicates
that the location corresponds to an optimal position for insertion
of the needle 110, then the user can insert the needle 110 through
the guideway 108. The guideway 108 is oriented parallel to the
second axis 412, offset a fixed and constant distance (e.g., 0 to 5
mm) from the second axis 412. By remaining offset from the second
axis 412, the inserted needle 110 interferes minimally with the
sound field present beneath the skin surface 112, and enables the
user to continually monitor the location of the vein 114 as the
needle is advanced, up until the time corresponding to when the
vein 114 is punctured. In one embodiment, the angle .beta. which is
the angle formed between the guideway 108 and the skin surface 112,
is approximately 30.degree., although other angles may be used.
[0041] FIG. 5 is a schematic diagram of another coupler embodiment,
coupler 102b, that illustrates application of the sound beam 408
and receiving the needle 110 along an axis 502 that has a depth
dependent offset relative to a sound beam axis 412. As shown, the
coupler 102b has similar components to those found in couplers 102,
102a of FIGS. 3 and 4, respectively, and thus discussion of the
same will be omitted or abbreviated. The sound beam 408 is radiated
from the transducer element 402 along the first axis 410, reflected
off a reflective portion 304b, and provided along the second axis
412 to impinge on the vein 114. The angle .alpha. is approximately
30.degree., although other angles may be used. The guideway 108
(and also the bottom surface of the reflective portion 304b in one
embodiment) form an angle .beta. of approximately 23.degree.,
although other angles may be used. Thus, the needle 110 is advanced
along the guideway 108 along a third axis 502, resulting in the
needle 110 intersecting the sound beam 408 provided along the
second axis 412 in a location proximally (i.e., the axis 502
intersecting axis 402 in a location approximately at the point
where the focal region ends, such as where the beam width ceases to
be 1 mm in diameter in embodiments described herein) to the vein
114. Note that the offset will vary based on the depth of the vein
114.
[0042] FIG. 6 is a front-view schematic diagram of the needle
insertion system 100 shown in FIG. 1 that illustrates traversing
the skin surface 112 to obtain a strong signal indicating location
of the vein 114 and/or optimal locations along the vein 114. For
example, the needle insertion system 100 is shown traversing across
the skin surface, but it also is traversable in the direction
running along the length of the body 106, as well as rotatably
traversable. In one implementation, the needle insertion system 100
is moved (represented by the double-arrow head above the system
100) across the skin surface 112 until the vein 114 is detected.
Vein detection (and/or location) may be indicated by a light, sound
or other display or feedback, as described above. The sound beam
reflection from the vein 114 enables the needle 110 (or an IV
catheter, for example, in some implementations) to be aligned, but
offset, with the sound beam 408. In other words, the sound beam 408
is known (using Doppler technology) to be passing through a
suitable vein 114. The needle is advanced through the guideway 108a
(parallel to, but offset from the sound beam 408 in this
implementation), passing through the skin surface 112 and advanced
until it punctures the vein 114. The user continually receives
feedback that he or she is advancing the needle 110 in the right
direction until the vein 114 is punctured.
[0043] FIG. 7A is a schematic diagram that illustrates another
embodiment of a needle insertion system 700. The needle insertion
system 700 differs from the prior described embodiments in that a
needle is advanced to a vein along an axis that is coincident with
the sound beam. The needle insertion system 700 includes a
transducer assembly 704 attached to the coupler 702. Preferably,
the transducer 704 is attachable and detachable from the coupler
702 (e.g., shown here as rotatably attachable and detachable). The
transducer assembly 704 includes the same or similar electronics to
the transducer assembly 104 shown in FIG. 2, and thus illustration
and discussion of the same is omitted.
[0044] FIG. 7B is a side-view cut-away of an embodiment of the
coupler 702 of the needle insertion system 700 shown in FIG. 7A.
With continued reference to FIG. 7A, the coupler 702 is preferably
made of plastic, and comprises membranes 706 and 708 and a chamber
710 that includes an ultrasonic coupling material (not shown).
Membranes 706 and 708 may be made of, for example, rubber. The
coupling material can be, for example, a sterile, de-aerated
saline. In one embodiment, the coupler 702 may be disposable, and
included with the needle 110 in a plastic package (not shown)
designed to maintain the sterility of the coupler 702 and the
needle 110. For IV catherization implementations, the coupler 702
can be designed to split in half to allow removal of the coupler
702 after the vein 110 has been punctured, an unnecessary step for
simply drawing blood. The membranes 706 and 708 are traversed by
the needle 110 during the insertion, the needle 110 being advanced
through the guideway 712. The membrane 706 is also an ultrasound
reflector. In one embodiment, the membrane 706 is air-backed and
preferably as smooth and flat as possible. The membrane 708 serves
to couple the sound beam 408 into the tissue of the body 106. In
some implementations, an ultrasonic coupling gel (not shown) may be
applied to the outside surface of the membrane 708 (i.e., the
surface contacting the skin surface 112).
[0045] Directing attention to FIG. 7A, the operation of the
transducer system 700 will now be described. The transducer element
402 of the transducer assembly 704 radiates the sound beam 408 a
distance (represented by the line labeled "B") of approximately 4
cm to the membrane 706 in similar manner to that described in
association with FIG. 4. The sound beam is radiated along a first
axis 410. The sound beam 408 is reflected by the air-backed
membrane 706 before entering the body 106 through the membrane 708.
The reflected sound beam 408 travels along the second axis 412. The
travel path and orientation of the reflected sound beam 408 enables
the needle 110 (or an IV catheter) to be exactly aligned or
substantially aligned with the reflected sound beam 408, which is
known by Doppler to be passing through a suitable vein 114.
Although the sound beam 408 is shown to make an angle .alpha. of
30.degree. relative to the plane of the skin surface 112, it would
be understood by one having ordinary skill in the art that some
embodiments may utilize one of a variety of different angles (e.g.,
45.degree. or 20.degree. depending on the application.
[0046] The needle 110 is advanced (not shown) through the guideway
712, which is coincident (or coaxial) with the sound beam 408. The
needle 110 is advanced through the membrane 706, through the
chamber 710 (and thus through a coupling material not shown, such
as saline fluid), and then through the membrane 708, and
continually (still along the second axis 412) advanced until the
needle 110 punctures the vein 114. The coaxial alignment of the
guideway 712 and sound beam assures (or assures with a
high-probability of certainty) that the needle 110 will encounter
the vein 114. The coupler 702, in one embodiment, can then be
easily disassembled into two or more pieces and removed, and the IV
cauterization or blood draw can be completed.
[0047] In some embodiments, the saline filled chamber 710 can be
replaced with a solid insert (not shown), which can be removed
after the vein 114 is detected to allow passage of the needle 110.
In such embodiments, the membranes 706 and 708 may be omitted and
the user can view the insertion point.
[0048] In view of the above description, it will be appreciated
that one embodiment of a needle insertion method 800 may comprise,
as illustrated in FIG. 8, transmitting a sound beam along an axis
to contact a blood vessel (802); receiving the reflected sound beam
from the blood vessel (804); processing the reflected sound beam to
detect the location of the blood vessel (806); and, responsive to
the detection, receiving a needle in a guideway that is oriented
parallel to the axis (808).
[0049] Another embodiment of a needle insertion method 900 may
comprise, as illustrated in FIG. 9, transmitting a sound beam along
a first axis to contact a blood vessel (902); receiving a reflected
sound beam reflected from the blood vessel along the first axis
(904); processing the reflected sound beam to detect the location
of the blood vessel (906); and, responsive to the detection,
receiving a needle in a guideway that is oriented along a second
axis that enables the needle to intersect the first axis in
proximity to the blood vessel (908).
[0050] Any process descriptions or blocks in the flow diagrams of
FIGS. 8 and 9 should be understood as representing steps in an
embodiment of one method, and alternate implementations are
included within the scope of the preferred embodiments, as would be
understood by those reasonably skilled in the art.
[0051] It should be emphasized that the above-described
embodiments, particularly, any "preferred" embodiments, are merely
possible examples of implementations, and are merely set forth for
a clear understanding of the principles of the disclosure. Many
variations and modifications may be made to the above-described
embodiment(s) without departing substantially from the spirit and
principles of the disclosure. All such modifications and variations
are intended to be included herein within the scope of this
disclosure.
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