U.S. patent application number 15/258781 was filed with the patent office on 2016-12-29 for medical tool with electromechanical control and feedback.
This patent application is currently assigned to Actuated Medical, lnc.. The applicant listed for this patent is Actuated Medical, lnc.. Invention is credited to Roger B. Bagwell, Ryan S. Clement, Paul L. Frankhouser, Gabriela Hernandez Meza, Maureen L. Mulvihill, Brian M. Park, Ryan M. Sheehan.
Application Number | 20160374723 15/258781 |
Document ID | / |
Family ID | 46638984 |
Filed Date | 2016-12-29 |
United States Patent
Application |
20160374723 |
Kind Code |
A1 |
Frankhouser; Paul L. ; et
al. |
December 29, 2016 |
Medical Tool With Electromechanical Control and Feedback
Abstract
A medical device for reducing the force necessary to penetrate
living being tissue using a variety of reciprocating motion
actuators. The reciprocating actuator drives a penetrating member,
such as a needle, through the tissue at a reduced force while the
device detects the passage of the penetrating member through the
tissue. Upon passage of the penetrating member through the tissue,
a feedback system monitors electromechanical properties of a
control signal of the device and automatically modifies control
based thereon, e.g., electrical power to the reciprocating actuator
is automatically terminated.
Inventors: |
Frankhouser; Paul L.; (Miami
Beach, FL) ; Mulvihill; Maureen L.; (Bellefonte,
PA) ; Bagwell; Roger B.; (Bellefonte, PA) ;
Clement; Ryan S.; (State College, PA) ; Hernandez
Meza; Gabriela; (State College, PA) ; Sheehan; Ryan
M.; (Pittsburgh, PA) ; Park; Brian M.;
(Bellefonte, PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Actuated Medical, lnc. |
Bellefonte |
PA |
US |
|
|
Assignee: |
Actuated Medical, lnc.
Bellefonte
PA
|
Family ID: |
46638984 |
Appl. No.: |
15/258781 |
Filed: |
September 7, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14976939 |
Dec 21, 2015 |
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15258781 |
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13371310 |
Feb 10, 2012 |
9220483 |
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14976939 |
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12559383 |
Sep 14, 2009 |
8328738 |
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13371310 |
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12163071 |
Jun 27, 2008 |
8043229 |
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12559383 |
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61441677 |
Feb 11, 2011 |
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61441500 |
Feb 10, 2011 |
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61089756 |
Sep 15, 2008 |
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60937749 |
Jun 29, 2007 |
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Current U.S.
Class: |
600/567 |
Current CPC
Class: |
A61B 2017/00026
20130101; A61B 90/06 20160201; A61B 2017/320089 20170801; A61B
2090/064 20160201; A61B 2017/00115 20130101; A61B 17/3401 20130101;
A61B 2017/00123 20130101; A61B 2017/32007 20170801; A61B 2017/0003
20130101; A61M 5/3287 20130101; A61M 19/00 20130101; A61B
2017/00477 20130101; A61B 2017/00039 20130101; A61M 2205/0294
20130101; A61B 10/025 20130101; A61M 5/46 20130101; A61M 25/0662
20130101; A61B 2017/3409 20130101; A61B 17/3476 20130101; A61M
2205/332 20130101; A61M 2025/0166 20130101; A61B 17/3415
20130101 |
International
Class: |
A61B 17/34 20060101
A61B017/34; A61M 5/32 20060101 A61M005/32; A61M 5/46 20060101
A61M005/46; A61M 19/00 20060101 A61M019/00; A61B 10/02 20060101
A61B010/02; A61B 90/00 20060101 A61B090/00 |
Goverment Interests
GOVERNMENT SUPPORT STATEMENT
[0002] This invention was made with government support under
contracts GM085844, RR024943, CA139774 and AG037214 awarded by the
National Institutes of Health. The government has certain rights in
the invention.
Claims
1-37. (canceled)
38. A device, comprising: a driving actuator having a displaceable
member formed of a first portion detachably connected to a second
portion, a rear mass, and a piezoelectric stack formed between the
displaceable member and rear mass; a penetrating member coupled to
a distal end of said second portion of said driving actuator; and
an electrical power feedback subsystem for regulating the operation
of said driving actuator based on a sensed condition, wherein said
second portion further comprises a channel extending entirely
therethrough.
39. The device of claim 38 further comprising a force sensor
disposed at a proximal end of said driving actuator.
40. The device of claim 39 wherein said force sensor further
comprises a piezoelectric ring.
41. The device of claim 38 further comprising a phase angle
detector for detecting passage of said distal end of said
penetrating member through a preselected space within living tissue
based on a phase angle of a control signal of said driving
actuator.
42. The medical device of claim 38 further comprising a voltage
detector for detecting passage of said distal end of said
penetrating member into a preselected space within living tissue
based on a voltage of a control signal of said driving
actuator.
43. The device of claim 38, further comprising a phase angle
detector for detecting changes in device operation conditions as
the device is exposed to various media.
44. The device of claim 38 wherein said second portion further
comprises a channel extending entirely therethrough.
45. The device of claim 44, wherein said second portion further
comprises an opening that is not in communication with said
channel.
46. The device of claim 44 wherein said channel comprises a first
section that accepts a proximal end of said penetrating member.
47. The device of claim 44 wherein said channel comprises a second
section that accepts material capable of being introduced to an
inner volume of the penetrating member.
48. The device of claim 44, wherein said channel accepts the
insertion of one of a syringe and a catheter.
49. A method, comprising: providing power from a power source to an
actuator of a medical device, the actuator configured to convert
the provided power into reciprocating motion at a first frequency
that is transferred to a sharps member coupled to the actuator;
detecting a reference resonance frequency of the medical device;
and automatically adjusting the power provided to the actuator to
cause the actuator to vibrate at the reference resonance
frequency.
50. The method of claim 49, wherein said step of detecting a
reference resonance frequency comprises: adjusting the power
provided by the power source to cause the actuator to reciprocate
at a plurality of frequencies within a range of frequencies, using
an impedance analyzer in communication with the actuator to measure
an impedance response signal of the actuator respective to each of
the plurality of frequencies, storing a first value representative
of each of the impedance response signals and a second value of
each of the corresponding plurality of frequencies in a machine
readable medium, comparing each of the stored first values of each
of the impedance response signals, selecting a minimum first value
relative to the other stored first values; determining the
frequency corresponding to the minimum first value and storing the
minimum first value to be the reference resonance frequency.
51. The method of claim 50, wherein said range of frequencies
comprises frequencies in the range of 19.5 kHz to 21.5 kHz.
52. The method of claim 50, wherein said range of frequencies
comprises frequencies in the range of 21 kHz to 24 kHz.
53. The method of claim 52, further comprising: detecting a change
in resonance frequency of the medical device relative to a
threshold resonance frequency change; determining an updated
resonance frequency of the medical device; and automatically
adjusting the power provided to the actuator to cause the actuator
to reciprocate at the updated resonance frequency.
54. The method of claim 53, wherein the step of detecting a change
in resonance frequency of the medical device relative to a
threshold resonance frequency change, comprises: adjusting the
power provided by the power source to cause the actuator to
reciprocate at a plurality of frequencies within a range of
frequencies, using an impedance analyzer in communication with the
actuator to measure an impedance response signal of the actuator
corresponding to each of the plurality of frequencies, storing a
first value representative of each of the impedance response
signals and a second value of each of the corresponding plurality
of frequencies in a machine readable medium, comparing each of the
stored first values of each of the impedance response signals,
selecting a minimum first value relative to the other stored first
values, determining the frequency corresponding to the minimum
first value; and determining a difference between the frequency
corresponding to the minimum first value relative to the reference
resonance frequency and comparing that difference to the threshold
resonance frequency change, and determining the updated resonance
frequency by selecting the minimum first value and storing said
minimum first value as an updated resonance frequency.
55. The method of claim 52, further comprising: detecting a change
in a detected phase angle relative to a threshold phase angle;
automatically adjusting the power provided by the power source to
cause the actuator to reciprocate by a predetermined frequency
change relative to the reference resonance frequency.
56. The method of claim 55, wherein the step of detecting a change
in a detected phase angle relative to a threshold phase angle
difference, comprises: detecting, at a first time, a phase angle of
the device operating at the reference resonance frequency at a
first time, detecting, at a second time, a phase angle of the
device operating at the reference resonance frequency, and
comparing a difference between the phase angle of the first time
and the phase angle of the second time to a predetermined threshold
phase angle difference.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This non-provisional application claims the benefit under 35
U.S.C. .sctn.119(e) of Provisional Application Ser. No. 61/441,500
filed on Feb. 10, 2011 entitled TRANSDUCER, NEEDLE, FEEDBACK AND
CONTROL DESIGN FOR REDUCED PENETRATION FORCE, and of Provisional
Application Ser. No. 61/441,677 filed on Feb. 11, 2011 entitled
MEDICAL TOOL FOR REDUCED PENETRATION FORCE WITH FEEDBACK MEANS
USING ELECTROMECHANICAL PROPERTIES and also is a
Continuation-in-Part application and claims the benefit under 35
U.S.C. .sctn.120 of application Ser. No. 12/559,383 filed on Sep.
14, 2009 entitled MEDICAL TOOL FOR REDUCED PENETRATION FORCE WITH
FEEDBACK MEANS which in turn claims the benefit under 35 U.S.C.
.sctn.120 of application Ser. No. 12/163,071 filed on Jun. 27, 2008
entitled MEDICAL TOOL FOR REDUCED PENETRATION FORCE which in turn
claims the benefit under 35 U.S.C. .sctn.119(e) of Provisional
Application Ser. No. 60/937,749 filed on Jun. 29, 2007 entitled
RESONANCE DRIVEN VASCULAR ENTRY NEEDLE and all of whose entire
disclosures are incorporated by reference herein.
BACKGROUND OF THE INVENTION
[0003] Field of the Invention
[0004] The present invention generally pertains to handheld medical
devices, and more specifically to electrically driven lancets;
epidural catheter inserters; biopsy medical instruments, such as
bone biopsy medical devices; vascular entry penetrating members,
spinal access needles and other catheterization needles. The
invention is applicable to the delivery and removal of blood,
tissues, medicine, bone marrow, nutrients or other materials within
the body.
[0005] Description of Related Art
[0006] Epidural anesthesia is a form of regional anesthesia
involving injection of drugs directly into the epidural space. To
begin the procedure, a needle is inserted from the outer layer of
skin, through several layers of tissue and finally placed within
the epidural space, through which a catheter is optionally passed.
Local anesthetics are injected into the epidural space causing
temporary loss of sensation and pain by blocking the transmission
of pain signals through nerves in or near the spinal cord. The
procedure can be unpleasant to the patient because of the high
force levels required for the relatively dull epidural needle to
penetrate the supraspinous ligament, interspinous ligament and
ligamentum flavum. One complication is that a clinician will
accidently overshoot and puncture the dura because of this high
force of penetration and an almost-instantaneous change in
resistance upon passing the needle into the epidural space (i.e.,
high forward momentum followed by instantaneous minimization of
force). Upon puncturing the dura, the cerebrospinal fluid can leak
into the epidural space causing the patient to experience severe
post dural puncture headache, lasting from days to possibly years.
Significant leakage can cause enough intracranial hypotension as to
tear veins, cause subdural heinatoma, and traction injuries to the
cranial nerves resulting in tinnitus, hearing loss, dizziness,
facial droop, or double vision.
[0007] A bone marrow biopsy is used for diagnosing tumors and a
variety of bone diseases. The most commonly used site for the bone
biopsy is the anterior iliac crest. A major disadvantage is the
force required to penetrate the bone tissue, and the twisting
motion often used to force the needle inward, which results in
patient discomfort as well as possible healing complications from
damaged tissues. The penetration force can also be tiring for
clinicians and lead to multiple sampling attempts. Complications
are rare but can include bleeding, pain, and infection. Pain is
minimized with proper local anesthesia, though the patient still
experiences a pressure sensation during insertion and retraction
during some procedures. Another problem is crushing the sample or
being unable to retrieve part of all of it, limiting the ability to
diagnose. As shown in FIG. 1, a biopsy tool PA1 typically comprises
a handle (not shown) and hollow cannula 1 with cannula distal end
1' surrounding a stylet 2 attached to the handle. To penetrate
through cortical bone, a clinician pushes the cannula and stylet
through the bone to the marrow. The distal tip 3 of the inner
stylet or trocar is sharpened and has an angled chisel-like face 4
which reduces the surface area to reduce the exertion force.
[0008] Currently, to minimize the possibility of a dura puncture,
the epidural catheter insertion process is typically performed very
slowly and with a 16-18 gauge, specially designed, relatively dull
needle PA2, such as the one shown in FIG. 2 called a Tuohy needle
5. An epidural needle, such as the Tuohy needle 5 or Hustead
needle, has a directional curved tip 6, which decreases the
"sharpness" at the needle and, therefore, makes accidental dura
puncture more difficult. The curved tip also facilitates directing
an indwelling catheter into the epidural space and a tip opening 7
facilitates catheter or fluid introduction or removal.
Unfortunately, this dull curved-tip design actually increases the
force a clinician must use and makes it more difficult for a
clinician to stop the forward momentum upon penetration of the
dural space. Additionally, the Tuohy design increases the
likelihood that a clinician relies on tactile feedback during
penetration. In other words, during the insertion procedure a
clinician will rely on feeling a "popping" sensation--indicative of
passing the needle past the ligamentum flavum--to locate the tip of
the needle within the epidural space and quickly stop the forward
momentum being applied. Still, because penetration into other
tissues, such as muscle, calcified ligament, or regular ligament
may produce a similar popping, a clinician may not fully perceive
the correct location of the needle tip where the tip of the needle
is occluded until passing through these tissues.
[0009] Several alternate technologies have been developed that
attempt to minimize the dura puncture risk, while also giving the
clinician indication of successful epidural placement. For example,
the detection method and apparatus disclosed in U.S. Patent
Application Publication No. 2007/0142766 (Sundar, et al.), the
contents of which are incorporated by reference, relies on a
spring-loaded plunger pushing a fluid into the epidural space upon
successful entry. Accordingly, the clinician is given a visual
indicator (i.e., the movement of the plunger as the fluid
experiences a loss of resistance at the needle opening), and would
cease applying forward force. Similarly, U.S. Pat. No. 5,681,283
(Brownfield) also relies on a visual indicator to communicate
successful entry of a needle into a cavity to the clinician.
Unfortunately, while a visual indicator is a positive advancement,
the actual cause of the accidental dural wall puncture--that is,
the high force applied by the clinician against the needle to pass
through the various tissue layers and then stop--is not taught or
suggested.
[0010] Therefore, there exists a need for a tool that reduces the
puncture force of a needle, such as a Tuohy needle, and enables a
clinician to perform a more controlled entry into the epidural
space, thereby reducing the possibility of an accidental dura
puncture.
[0011] While accidental dura puncture is a concern, simply locating
the epidural space may pose a challenge even to the most skilled
physicians. Therefore, when a needle such as a Tuohy needle is
passed through the ligamentum flavum and into the epidural space,
it is helpful for a clinician to receive immediate feedback
indicating successful penetration and the location of the tip of
the needle. A basic conventional feedback device such as the one in
FIG. 2a comprises a needle (not shown) attached to a syringe PA3 at
a front portion 9, and wherein the syringe PA3 is formed of a
tubular body 10 and houses a biasing element 11 comprising a stem
acting as a biasing element. To provide feedback indicating
successful epidural penetration the device relies on a biasing
force acting against the biasing element 11 which then acts upon a
fluid, such as saline or air within the syringe. Essentially, in
this hydraulic feedback method, as the biasing force acts upon the
fluid, the fluid translates this pressure to an opening of the
needle tip. An opposing force, acting on the needle tip as it is
held against a tissue such as the ligamentum flavum, acts to
prevent the fluid from being released from the syringe. Typically,
a clinician's thumbs act as the biasing force source which in turn
acts upon the plunger stem. The clinician's thumbs serve to "feel"
the hydraulic resistance exerted on the fluid by the opposing
tissue force. Upon entering the epidural space, however, the
opposing pressure of tissue acting against the tip is removed, and
a pressure drop allows the biasing force to move solution out of
the syringe through the needle tip. The clinician becomes aware of
successful penetration of the epidural space due to his/her thumbs
"feeling" the sudden pressure drop or loss of resistance at the
plunger stem. Also, the clinician may receive visual indication of
successful penetration by witnessing the plunger advancing through
the syringe externally as the fluid is released into the epidural
space in the patient. One problem with this conventional device and
method is that it is difficult for a clinician to both apply a
biasing force on the plunger while also applying an advancing force
against the syringe body in order to advance the needle through the
ligamentum flavum. Moreover, to prevent accidental dura puncture,
clinicians tend to hold the conventional syringe in such a way as
to hold the patient steady, while applying a forward momentum
against the syringe, and while applying a biasing force against the
plunger stem. This is both awkward and uncomfortable to the
clinician and patient.
[0012] Some advancements have also attempted to provide an
automatic biasing element to act against the plunger of an epidural
syringe while also providing visual indication or feedback, rather
than tactile response, of successful puncture of various internal
target areas in the human body. For example, in U.S. Patent
Publication No. 2007/0142766 (Sundar et al.), a spring is utilized
to act with a biasing force against the syringe plunger. When the
epidural needle attached to the syringe passes through into the
dural space, the pressure drop allows the spring to bias the
plunger. As the plunger moves, the stem provides at least some
visual indication as it moves with the plunger. Similarly, U.S.
Pat. No. 5,024,662 (Menes et al.), which is hereby incorporated by
reference, provides visual indication by utilizing an elastomer
band to provide the biasing force against the plunger stem. In U.S.
Pat. No. 4,623,335 (Jackson) which is hereby incorporated by
reference, an alternative device assists in visually indicating a
pressure to identify the location of the needle tip. In addition,
U.S. Pat. No. 7,297,131 (Call) which is hereby incorporated by
reference, uses a pressure transducer to translate a pressure
change into an electronic signal. The electronic signal is then
converted to a visual display indicator, for example by activating
a light emitting diode to emit.
[0013] Therefore, a need exists to overcome the challenges not
addressed by conventionally available technologies that reduces the
force necessary for penetration of a sharp medical element of a
medical device through tissue and also has the ability to deliver
(e.g., deliver saline solution, or drugs, etc.) or retrieve
materials subcutaneously (e.g., bone biopsy, etc.).
[0014] A need also exists to provide visual, tactile, electrical or
additional indication to a clinician that the penetrating member
has successfully penetrated the specific body space such as the
epidural space, especially when the force to enter such a space has
been substantially reduced. And this same force reduction must be
either controlled or shut off immediately upon entry into the
epidural space to avoid (easier) penetration of the dura.
[0015] Specifically, a need exists in the medical device art for an
improved medical device having a penetrating element that is
vibrated at a frequency that thereby reduces the force required to
penetrate tissue, reduces the amount of resulting tissue damage and
scarring, improving body space or vessel access success rate,
minimizes introduction wound site trauma and, most importantly,
improves patient comfort while minimizing potential
complications.
[0016] A need exists for a clinician to be able to use less force
to penetrate hard tissue such as the cortical bone during bone
biopsy, which would reduce clinician fatigue, patient discomfort,
and tissue damage while improving the sampling success rate and
quality. There is a need to sense proper location, stop forward
motion and collect the sample. There is a further need to turn
device on after collection and to reduce force and patient
discomfort as the penetrating member is being retracted from the
body.
[0017] There is also a need for spinal access procedures where a
clinician would want a reduction of force as well as to know the
location of the needle tip but applied to a relatively-sharp
penetrating member, such as a pencil point tip, as the clinician
does not want to core tissue.
[0018] There is also a need for performing nerve block procedures
where a clinician would want a reduction of force as well as to
know the location of the needle tip. And this same force reduction
must be either controlled or shut off immediately upon entry into
the desired location.
[0019] All references cited herein are incorporated herein by
reference in their entireties.
SUMMARY OF THE INVENTION
[0020] The basis of the invention is a handheld medical device,
(e.g., epidural needle, bone biopsy device, spinal needle, regional
block needle, catheter introducer needle, etc.) having a
penetrating member (e.g., an introducer needle, Tuohy needle,
pencil point tipped needle, trocar needle (e.g., JAMSHIDI.RTM.
biopsy needle), etc.), at a distal end, for use in procedures,
(e.g., vascular entry and catheterization, single shot or
continuous epidurals, spinal access, regional blocks, or bone
biopsy, etc.), wherein the medical device comprises at least one
driving actuator, (e.g., a piezoelectric, voice coil, solenoid,
pneumatic, fluidic or any oscillatory or translational actuator
etc.) attached to the penetrating member (e.g., at a proximal end
of the penetrating member), and wherein the driving actuator
translates the penetrating member, causing it to reciprocate at
small displacements, thereby reducing the force required to
penetrate through tissues.
[0021] Additionally, the invention comprises a means for providing
feedback, either visually, audibly, or by tactile response, using a
variety of detection mechanisms (such as, but not limited to,
electrical, magnetic, pressure, capacitive, inductive, etc. means),
to indicate successful penetration of various tissues, or of voids
within the body such as the epidural space so that the clinician
knows when to stop as well as to limit power to the driving
mechanism.
[0022] Actuator technologies that rely on conventional, single or
stacked piezoelectric material assemblies for actuation are
hindered by the maximum strain limit of the piezoelectric materials
themselves. Because the maximum strain limit of conventional
piezoelectric materials is about 0.1% for polycrystalline
piezoelectric materials, such as lead zirconate titanate (PZT)
polycrystalline (also referred to as ceramic) materials and 0.5%
for single crystal piezoelectric materials, it would require a
large stack of cells to approach useful displacement or actuation
of for example, a handheld medical device usable for processes
penetrating through tissues. However, using a large stack of cells
to actuate components of a handpiece would also require that the
tool size be increased beyond usable biometric design for handheld
instruments.
[0023] Flextensional actuator assembly designs have been developed
which provide amplification in piezoelectric material stack strain
displacement. The flextensional designs comprise a piezoelectric
material driving cell disposed within a frame, platen, endcaps or
housing. The geometry of the frame, platten, endcaps or housing
provides amplification of the axial or longitudinal motions of the
driver cell to obtain a larger displacement of the flextensional
assembly in a particular direction. Essentially, the flextensional
actuator assembly more efficiently converts strain in one direction
into movement (or force) in a second direction. Flextensional
piezoelectric actuators may be considered mid-frequency actuators,
e.g., 25-35 kHz. Flextensional actuators may take on several
embodiments. For example, in one embodiment, flextensional
actuators are of the Cymbal type, as described in U.S. Pat. No.
5,729,077 (Newnham), which is hereby incorporated by reference. In
another embodiment, flextensional actuators are of the amplified
piezoelectric actuator ("APA") type as described in U.S. Pat. No.
6,465,936 (Knowles), which is hereby incorporated by reference. In
yet another embodiment, the actuator is a Langevin or bolted
dumbbell-type actuator, similar to, but not limited to that which
is disclosed in U.S. Patent Application Publication No.
2007/0063618 A1 (Bromfield), which is hereby incorporated by
reference.
[0024] In a preferred embodiment, the present invention comprises a
handheld device including a body, a flextensional actuator disposed
within said body and a penetrating or "sharps" member attached to
one face of the flextensional actuator. In the broadest scope of
the invention, the penetrating member may be hollow or solid. The
actuator may have an internal bore running from a distal end to a
proximal end or may have a side port located on the penetrating
member attachment fitting. Therefore for single use penetrating
members there is no need to sterilize the penetrating member after
use. Where the penetrating member is hollow, it forms a hollow
tubular structure having a sharpened distal end. The hollow central
portion of the penetrating member is concentric to the internal
bore of the actuator, together forming a continuous hollow cavity
from a distal end of the actuator body to a proximal end of the
penetrating member. For example, the flextensional actuator
assembly may utilize flextensional Cymbal actuator technology or
amplified piezoelectric actuator (APA) technology. The
flextensional actuator assembly provides for improved amplification
and improved performance, which are above that of a conventional
handheld device. For example, the amplification may be improved by
up to about 50-fold. Additionally, the flextensional actuator
assembly enables handpiece configurations to have a more simplified
design and a smaller format.
[0025] One embodiment of the present invention is a resonance
driven vascular entry needle to reduce insertion force of the
penetrating member and to reduce rolling or collapsing of
vasculature.
[0026] An alternative embodiment of the present invention is a
reduction of force epidural needle that provides the clinician a
more controlled entry into the epidural space, minimizing the
accidental puncturing of the dural sheath. In this embodiment, an
actuator, for example, a Langevin actuator (more commonly referred
to as a Langevin transducer), has a hollow penetrating member, for
example a hollow needle, attached to a distal portion of the
actuator. The Langevin actuator in this embodiment may be open at
opposite ends. The openings include a hollow portion extending
continuously from the distal end of the actuator to a proximal end
of the actuator. The distal opening coincides with the hollow
penetrating member. A plunger, having a handle, a shaft and a seal
is also attached to the actuator at an opposite end of the sharps
member. The plunger's shaft is slidably disposed within the
continuous, hollowed inner portion of the actuator. The seal is
attached to a distal portion of the plunger's shaft and separates a
distal volume of the hollowed inner portion of the actuator from a
proximal volume of the hollowed inner portion. Because the
plunger's shaft is slidably disposed, the plunger is also slidably
disposed and, in response to a motion of the shaft in a distal
direction, reduces the distal volume of the hollowed inner portion
and increases the proximal volume. Conversely, in response to a
motion of the shaft in a proximal direction, the seal also moves in
a proximal direction, thereby reducing the proximal volume of the
hollowed portion and increasing the distal volume. The motion of
the plunger's shaft, and, effectively, the plunger's seal, is
actuated by an external force acting on the plunger's handle. When
electrically activated, the actuator transfers compression and
expansion of the piezoelectric material portion to a hollow and
penetrating tip of the hollow needle. Langevin actuators may be
considered high frequency actuators, e.g., >50 kHz.
[0027] Another embodiment of the invention provides a bone marrow
biopsy device having an outer casing, an actuator, for example, a
Langevin actuator (e.g., see, for example, U.S. Pat. No. 6,491,708
(Madan, et al.), whose entire disclosure is incorporated by
reference herein), including a first body portion and a second body
portion of the actuator, with piezoelectric material formed between
the first and second body portions, wherein the actuator is
disposed at least partially within the casing. The invention
further includes a handle, an outer cannula, such as a needle,
having an open distal end and an open proximal end with the cannula
positioned at a distal portion of the actuator. In one aspect of
the present embodiment, the invention further comprises a stylet
having a penetrating distal tip attached to the handle at a portion
opposite the distal tip, wherein the stylet is slidably disposed
through a center cavity of the body and cannula. The actuator is
formed with a distal opening formed at a distal end of the
actuator, and a proximal opening formed at a proximal end of the
actuator with a centralized hollow bore extending from the distal
opening to the proximal opening, thereby defining a hollow
channel.
[0028] More precisely, the outer cannula is a hollow tube fixedly
attached at the distal end of the actuator such that the open
proximal end of the cannula coincides with the distal opening of
the actuator distal end. The stylet is slidably and centrally
disposed within the actuator from the proximal end through the
hollow channel and through the distal end. The stylet is also of
predetermined length such that it is slidably and centrally located
through the outer cannula, with the distal tip of the stylet
protruding past the open distal end of the cannula.
[0029] The various actuators of the present invention must be
connected electrically to an external electrical signal source.
Upon excitation by the electrical signal, the actuators convert the
signal into mechanical energy that results in vibratory motion of
an end-effector, such as an attached needle or stylct. In the case
of a Langevin actuator, the vibratory motion produced by the
piezoelectric materials generates a standing wave through the whole
assembly such as that in graph in FIG. 17. Because at a given
frequency, a standing wave is comprised of locations of
zero-displacement (node, or zero node) and maximum displacement
(anti-node--not shown) in a continuous manner, the displacement
that results at any point along the actuator depends on the
location where the displacement is to be measured. Therefore, the
horn is typically designed with such a length so as to provide the
distal end of the horn at an anti-node when the device is operated.
In this way, the distal end of the horn experiences a large
vibratory displacement in a longitudinal direction with respect to
the long axis of the actuator. Conversely, the zero node points are
locations best suited for adding port openings or slots so as to
make it possible to attach external devices to the actuator. As
indicated by line ZN, the port opening SP coincides with the zero
node location and the smaller displacement at zero node points are
less abrasive to an attached device.
[0030] Accordingly, an alternative embodiment, the actuator may be
formed with a distal opening formed at the distal end of the
actuator, a port opening on at least a portion of the actuator, and
a hollow bore extending from the distal opening to and in
communication with the port opening. Preferably, the port opening
may be a side port on a horn side of the actuator. More preferably,
the port opening is generally located (preferably centered) at a
zero node location of the actuator, and most preferably centered at
a zero node location on a horn side of the actuator. Additionally,
a means for providing feedback, for example any of those
conventional feedback devices disclosed above used for indication
of successful body location such as the epidural space penetration
is in communication with the present embodiment by attachment at
the port opening location, or preferably at the side port.
Alternatively, any means capable of delivering fluid, such as a
catheter tube or conventional syringe can be attached at the port
opening location, or preferably at the side port.
[0031] The present invention relates generally to oscillatory or
translational actuated handheld device for penetration through
various tissues within a body for the delivery or removal of bodily
fluids, tissues, nutrients, medicines, therapies, placement or
removal of catheters, etc. For example for piezoelectric devices,
the present invention is a handpiece including a body, at least one
piezoelectric element disposed within the body, and a sharps member
for tissue penetration, such as a syringe, epidural needle or
biopsy needle located at a distal portion of the handheld device,
having a feedback means capable of indicating successful
penetration of the body space, such as epidural space by providing
visual, audible or tactile indications using any well-known
detection mechanisms such as but not limited to electrical,
magnetic, pressure, capacitive, inductive, etc. means.
[0032] Additionally, with the use of proper circuitry the handheld
medical device comprising an actuator is provided with a means for
shutting off external power to the driving actuator (e.g., one or
more of piezoelectric elements, voice coil, solenoid, other
oscillatory or translational actuator, etc.) upon penetration of a
particular tissue or internal portion of a body such as the
epidural space. The means for shutting off external power to the
driving actuator may be implemented as part of the aforementioned
means for providing visual, audible or tactile indications or may
be a separate means altogether. Preferably the means for shutting
off external power to the driving actuator upon penetration of a
particular tissue or internal portion of for example, the epidural
space, may be accomplished by incorporating proper circuit
configurations to aforementioned electrical means to trigger a
switching means in order to cut off power to the driving actuator.
Such a means is described in U.S. Pat. No. 5,575,789 (Bell et al.)
whose entire disclosure is incorporated by reference herein. By
providing such electrical cut-off means, upon successfully
penetrating the epidural space for example, a clinician receives
one or more of a visual, audible, and tactile indications as well
as a loss of power to the device as a secondary indication that a
particular internal portion of a body has been penetrated.
Furthermore, with a loss of power to the device by cutting off
electrical power to the driving actuator, the force or forward
momentum necessary for further penetration of tissue will cease and
in turn, will decrease the potential for unwanted body area
puncture such as accidental dural puncture.
[0033] Additionally the invention with specific control electronics
will provide reduction of force as the penetrating member is
retracted from the body.
[0034] In one embodiment, the penetrating or sharp tubular member
is a part of a vascular entry needle.
[0035] In another embodiment, the penetrating sharp tubular member
is a Tuohy needle.
[0036] In yet another embodiment, the penetrating or sharp tubular
member is a trocar and stylet assembly, such as a JAMSHIDI.RTM.
biopsy needle.
[0037] In yet another embodiment, the penetrating or sharp tubular
member is a pencil point tipped needle.
[0038] In yet another embodiment, the penetrating or sharp tubular
member is part of a trocar access port.
[0039] In an embodiment, a medical device for penetrating living
being tissue is provided. The device can include a driving actuator
for converting electrical energy into reciprocating motion when
energized. The driving actuator can include a distal end and a
first channel extending to the distal end, and a penetrating member
can be coupled to the distal end of the driving actuator. The
medical device can include a feedback subsystem that detects any
change of electromechanical properties related to the operation of
the penetrating member for: (i) indicating to an apparatus operator
a different type of tissue has been contacted by said penetrating
member; and/or (ii) automatically controlling force being applied
to said penetrating member.
[0040] In an embodiment, a method for reducing the force needed to
penetrate living being tissue based on the tissue being encountered
during the insertion of a sharps member is provided. The method can
include the step of establishing characteristic electromechanical
property changes of a vibrating reference member having a sharps
member that passes through various tissues that correlates said
changes with particular tissues. The method can include
reciprocating the sharps member against the living being tissue
using a reciprocating actuator that converts electrical energy to
reciprocating motion. The method can include detecting a change in
said characteristic electromechanical property. The method can
include the step of comparing said detected change against said
correlation and indicating to an operator of said cutting member
the type of tissue that is being currently encountered based on the
change in said characteristic electromechanical property. The
method can include the step of comparing said detected change
against said correlation and for automatically controlling the
force being applied to said sharps member
[0041] In an embodiment, a device is provided. The device can
include an actuator. The actuator can include a displaceable member
formed of a first portion detachably connected to a second portion,
a rear mass, and a piezoelectric stack formed between the
displaceable member and rear mass. The device can include a sharps
member coupled to a distal end of the second portion. The device
can include an electrical power feedback subsystem for
automatically controlling the power to the actuator based on a
sensed condition.
[0042] In an embodiment, a method is provided. The method can
include the step of providing power from a power source to an
actuator of a medical device, the actuator configured to convert
the provided power into reciprocating motion at a first frequency
that is transferred to a sharps member coupled to the actuator. The
method can include the step of detecting a reference resonance
frequency of the medical device. The method can include
automatically adjusting the power provided to the actuator to cause
a actuator to vibrate at the reference resonance frequency.
[0043] These and other features of this invention are described in,
or are apparent from, the following detailed description of various
exemplary embodiments of this invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0044] Exemplary embodiments of this invention will be described
with reference to the accompanying figures.
[0045] FIG. 1 is a partial isometric view of a distal end of a
prior art biopsy needle;
[0046] FIG. 2 is a partial side view of a distal end of a prior art
epidural needle;
[0047] FIG. 2a is a plan view of a conventional prior art loss of
resistance syringe;
[0048] FIG. 3 is a graph illustrating the penetration force of a
penetrating member;
[0049] FIG. 4 is a cross section of a Langevin actuator, more
commonly referred to as a Langevin transducer, for use as an
actuator in a first embodiment of the present invention;
[0050] FIG. 4a is needle design with the side port located in the
penetrating member hub providing external access such as for
pressure sensor connection or catheter entry location.
[0051] FIG. 5 is a cross section of a vascular entry needle used in
a first embodiment of the invention;
[0052] FIG. 6 is a cross section of a plunger used in a first
embodiment of the invention;
[0053] FIG. 6a depicts the present invention including a
sterilization sleeve for wires and housing;
[0054] FIG. 6b depicts the present invention including a battery
and inverter compartment attached at the end of the actuator;
[0055] FIG. 7 is a cross section of a first embodiment of the
invention;
[0056] FIG. 7a is a cross-section of an alternate design of the
first embodiment of the invention that incorporates the side port
on the penetrating member hub.
[0057] FIG. 8 is a cross section of another alternate design of the
first embodiment of the invention of FIG. 7;
[0058] FIG. 9 is an isometric view of a second embodiment of the
present invention;
[0059] FIG. 9a is an isometric view of an alternate design of the
second embodiment using a side port on the actuator for attachment
location of the pressure sensor or entry of a catheter;
[0060] FIG. 9b is an isometric view of more preferred alternate
design of the second embodiment using a side port on the
penetrating member hub for attachment location of the pressure
sensor or entry of a catheter;
[0061] FIG. 10a is a cross section of an inner stylet for use in a
third embodiment of the present invention;
[0062] FIG. 10b is a cross section of an outer penetrating member,
such as a trocar, for use in a third embodiment of the present
invention;
[0063] FIG. 10c is a cross section showing the relative positioning
of the inner stylet of FIG. 10a within the outer penetrating member
of FIG. 10b for use in a third embodiment of the present
invention;
[0064] FIG. 11 is a cross section of a third embodiment of the
present invention;
[0065] FIG. 12 is a cross section of a fourth embodiment of the
present invention;
[0066] FIG. 13 is a cross section of a penetrating member attached
to an amplified piezoelectric actuator for use in a fifth
embodiment of the present invention;
[0067] FIG. 13a is cross section of an alternate APA design of a
penetrating member with side port for use the present
invention;
[0068] FIG. 14 is a cross section of a fifth embodiment of the
present invention;
[0069] FIG. 14a is a cross section of the fifth embodiment of the
present invention using a penetrating member with side port of FIG.
13a;
[0070] FIG. 15 is a cross section of a sixth embodiment of the
present invention comprising a Cymbal actuator;
[0071] FIG. 16 is a cross section of the sixth embodiment of the
present invention using the penetrating member with side port of
FIG. 13a;
[0072] FIG. 17 shows the correlation between zero node points of a
standing wave and the location of a side port on a Langevin
actuator without the actuator handle shown;
[0073] FIG. 17a shows the correlation between zero node points of a
standing wave and the location of a side port on the penetrating
member connected to the Langevin actuator;
[0074] FIG. 18a is a functional diagram of a seventh embodiment of
the present invention depicting a side port at a zero node location
on a Langevin actuator without the handle shown;
[0075] FIG. 18b is a functional diagram of a seventh embodiment of
the present invention comprising the side port of FIG. 18a in
communication with a central channel extending the length of a
Langevin actuator and without the handle shown;
[0076] FIG. 18c is a sketch of a eighth embodiment of the present
invention comprising two side ports in communication with needle
attachment one connected to the front portion of the Langevin
actuator and the other connected to the penetrating member without
the actuator handle shown;
[0077] FIG. 18d is a sketch of a eighth embodiment of the present
invention comprising the side port connected to the short bore and
communication with needle attachment that is also connected to the
front portion of the Langevin actuator and without the handle shown
of the actuator of FIG. 18a;
[0078] FIG. 19 is a drawing of a ninth embodiment of the present
invention comprising a conventional syringe of FIG. 2a attached at
the side port location of the actuator shown in FIG. 18a and
without the actuator handle shown;
[0079] FIG. 19a is a drawing of a ninth embodiment of the present
invention comprising a conventional syringe of FIG. 2a attached at
the side port location of the penetrating member hub shown in FIG.
18c with the actuator also connected into the hub and without the
actuator handle shown;
[0080] FIG. 19b is a drawing of a pressure sensing pump system for
connection to a penetrating member.
[0081] FIG. 20a is a cross-sectional view of a tenth embodiment of
the present invention using a voice coil for the driving
actuator;
[0082] FIG. 20b is a cross-sectional view of the tenth embodiment
of the present invention using a voice coil for the driving
actuator wherein the position of the magnetic member and the coil
are reversed from that of FIG. 20a;
[0083] FIG. 20c is an isometric cross-sectional view of the tenth
embodiment of the present invention using two coils;
[0084] FIG. 20d is a side cross-sectional view of the tenth
embodiment of the present invention using a solenoid with springs;
and
[0085] FIG. 21 is an exemplary schematic of an electrical power cut
off for use in the various embodiments of the present
invention.
[0086] FIG. 22 is a flow diagram of how the feedback subsystem of
the present invention operates;
[0087] FIG. 23 is a graph of test data (e.g., device impedance
data) of the vibrating reference member versus the material being
tested; and
[0088] FIG. 24 is an exemplary schematic of a feedback subsystem
for use in the various embodiments of the present invention.
[0089] FIGS. 25a-b shows a side view of a device of an additional
embodiment of the present invention.
[0090] FIG. 25c shows a side view of a device of an additional
embodiment of the invention.
[0091] FIGS. 26a-26c show perspective, side and cross sectional
views of a second portion of a horn of the invention.
[0092] FIG. 27 is a flow diagram of how an alternate feedback
subsystem of the present invention operates;
[0093] FIG. 28 is an exemplary schematic of a feedback subsystem
for use in the various embodiments of the present invention.
[0094] FIG. 29 is a graph of test data (e.g., Resonance Frequency,
Impedance Magnitude, Phase Angle, Penetration Force) of a reference
device versus time (msec);
[0095] FIG. 30 is a graph of test data (e.g., impulse voltage
response) of a reference device as a sharps member thereof
penetrates into the epidural space;
[0096] FIG. 31 is a graph of test data (e.g., impedance phase angle
of a dry needle and impedance phase angle of a saline filled
needle) of a reference device versus frequency (Hz)
[0097] FIGS. 32a-d show how a frequency sweep is performed to
calculate impedance minimum in an overall calculation of resonant
frequency, and how the value of impedance magnitude and phase angle
shift .theta. change.
[0098] FIG. 33 is a flow diagram showing steps of a method utilized
by a feedback method of an embodiment.
BRIEF DESCRIPTION OF THE INVENTION
[0099] The preferred embodiments of the present invention are
illustrated in FIGS. 3-21 with the numerals referring to like and
corresponding parts. For purposes of describing relative
configuration of various elements of the invention, the terms
"distal", "distally", "proximal" or "proximally" are not defined so
narrowly as to mean a particular rigid direction, but, rather, are
used as placeholders to define relative locations which shall be
defined in context with the attached drawings and reference
numerals. A listing of the various reference labels are provided at
the end of this Specification. In addition, U.S. Ser. No.
12/163,071 entitled "Medical Tool for Reduced Tool Penetration
Force," filed on Jun. 27, 2008 is incorporated by reference in its
entirety.
[0100] The effectiveness of the invention as described, for
example, in the aforementioned preferred embodiments, utilizes
reduction of force to optimize penetrating through tissue or
materials found within the body. Essentially, when tissue is
penetrated by the high speed operation of a penetrating member
portion of the device, such as a needle, the force required for
entry is reduced. In other words, a reduction of force effect is
observed when a penetrating member (also referred to as a "tubular
member"), for example a needle, is vibrated axially (e.g.,
reciprocated) during the insertion process and enough mechanical
energy is present to break adhesive bonds between tissue and the
penetrating member. The threshold limits of energy can be reached
in the sonic to ultrasonic frequency ranges if the necessary amount
of needle displacement is present.
[0101] To exploit the reduction of force effect, the medical device
of the present invention is designed such that the penetrating
distal tip portion attains a short travel distance or displacement,
and vibrates sinusoidally with a high penetrating frequency.
Utilizing the various device configurations as described in the
aforementioned embodiments, it has been determined that the
sinusoidal motion of the sharp distal tip must include a
displacement for piezoelectric tools of between 35-100 .mu.m, more
preferably between 50-100 .mu.m, at a frequency of between 20-50
kHz, but most preferably at 20-25 kHz. This motion is caused by the
penetrating member 20 being attached to an actuating piezoelectric
actuator operated at 50-150 Vpp/mm, but most preferably at 90
Vpp/mm where Vpp is known as the peak-to-peak voltage.
[0102] For example, FIG. 3 shows a graphical representation of the
resisting force versus depth of a bone biopsy needle penetrating
into hard tissue. In FIG. 3, the curve labeled A represents data
for a needle in an "off" or non-vibrating condition and the curve
labeled B represents data for a medical device having a needle that
is vibrated by a piezoelectric actuator at 38 kHz and a
displacement of 100 .mu.m. As apparent from FIG. 3, curve A shows
that without being vibrated, the force necessary to penetrate into
a material is much higher than that for a needle being oscillated,
such as that represented by curve B.
[0103] By way of example only, referring to FIG. 4, a Langevin
actuator, generally indicated as 100, comprises a piezoelectric
actuator which includes a body having a central hollow channel and
includes a displaceable member (also referred to as a "horn") 110,
an anchor (also referred to as a "rear mass") 112 and at least one
piezoelectric element 114, but preferably comprises more than one.
In particular, each piezoelectric element 114 may be formed into a
piezoelectric ring that forms a hollow portion and wherein the
piezoelectric elements 114 are secured within the body and attached
between horn 110 and rear mass 112. A hollow or solid threaded bolt
116 is disposed within a center portion of rear mass 112, extending
through a center portion of the at least one of piezoelectric
elements 114 and ending within a central portion of horn 110. The
bolt compresses the rear mass 112, the at least one of
piezoelectric elements 114 and horn 110. The horn 110 and rear mass
112 are made of a metal such as titanium, stainless steel, ceramic
(which include polycrystalline and single crystal inorganic
materials), plastic, composite or, preferably, aluminum. The bolt
116 is of the same material as the horn 110 and rear mass 112. To
protect patient and clinician from electric shock, at least a
portion of the Langevin actuator 100, preferably at least the whole
of the rear body 112, all of the at least one piezoelectric
elements 114, and at least a portion of the horn 110, are disposed
within a handle 118. Electrical connection is made at metallic tabs
(not shown) formed between opposing faces of the at least one of
piezoelectric elements 114. These tabs can be coupled via
electrical conductors 114b connected to an AC power source or
battery (e.g., positioned within a battery compartment of the
present invention). The handle 118 comprises a shell portion which
may be a plastic or a metal and a seal 120 which may be an
elastomer. Seal 120 prevents moisture from entering or exiting from
the central portions of the rear mass 112, piezoelectric elements
114 and horn 110. The central portion of the rear mass 112,
piezoelectric elements 114 and horn 110 coincide with the hollow
portion of the bolt 116 forming a continuous bore 126 within the
Langevin actuator 100, the bore 126 having a distal opening 122 at
a distal face 121 and a proximal opening 124 at a face opposite to
the distal face 121. A Luer taper nose 123 is added to the actuator
for clarity of connection.
[0104] It should be understood that the number of piezoelectric
elements 114 does not form a limitation on the present invention
and that it is within the broadest scope of the present invention
to include one or more piezoelectric elements 114.
[0105] According to an alternative embodiment, a side port (not
shown) may be formed at the horn 110 side of the actuator and the
continuous bore 126 extends from a distal opening 122 at distal
face 121 and in communication with this side port.
The functional performance of the medical device is driven by the
piezoelectric elements section. Piezoelectric elements 114, such as
each of one or more piezoelectric material rings are capable of
precise, controlled displacement and can generate energy at a
specific frequency. The piezoelectric materials expand when exposed
to an electrical input, due to the asymmetry of the crystal
structure, in a process known as the converse piezoelectric effect.
Contraction is also possible with negative voltage. Piezoelectric
strain is quantified through the piezoelectric coefficients
d.sub.33, d.sub.31, and d.sub.15, multiplied by the electric field,
E, to determine the strain, x, induced in the material.
Ferroelectric polycrystalline materials, such as barium titanate
(BT) and lead zirconate titanate (PZT), exhibit piezoelectricity
when electrically poled. Simple devices composed of a disk or a
multilayer type directly use the strain induced in a material by
the applied electric field. Acoustic and ultrasonic vibrations can
be generated by an alternating field tuned at the mechanical
resonance frequency of a piezoelectric device. Piezoelectric
components can be fabricated in a wide range of shapes and sizes.
In one embodiment, piezoelectric component may be 2-5 mm in
diameter and 3-5 mm long, possibly composed of several stacked
rings, disks or plates. The exact dimensions of the piezoelectric
component are performance dependent. The piezoelectric single or
polycrystalline materials may be comprised of at least one of lead
zirconate titanate (PZT), multilayer PZT, lead magnesium
niobate-lead titanate (PMN-PT), multilayer PMN-PT, lead zinc
niobate-lead titanate (PZN-PT), polyvinylidene difluoride (PVDF),
multilayer PVDF, and other ferroelectric polymers. These materials
also can be doped which changes properties and enhances the
performance of the medical device. This list is not intended to be
all inclusive of all possible piezoelectric materials. For example
there is significant research into non-lead (Pb) containing
materials that once developed will operate in this invention.
[0106] In the embodiment shown in FIG. 4a the side port SP is
located on the penetrating member hub 525 of the hollow needle 130.
In this alternate embodiment the hollow needle 130 penetrating
member hub 525 is preferably metal or a combination of metal insert
molded in a plastic. The side port SP would contain a female Luer
taper opening to attach a loss of resistance conventional syringe
PA3.
[0107] Referring now to FIG. 5, a penetrating member, generally
indicated as 20, for use in a first embodiment of the present
invention comprises an attachment fitting 128 connected to proximal
end 130b and the distal end 130a of a hollow needle 130 penetrates
tissue. By way of example only, the attachment fitting 128 may
comprise a Luer taper, plastic or metal fitting.
[0108] Referring now to FIG. 6, a plunger 12 for use in a first
embodiment of the present invention comprises a plunger handle 132
attached to a proximal end 134a of a plunger shaft 134, and a
plunger seal 136 attached to a distal end 134b of the plunger shaft
134. The plunger seal is used to seal the handle 118 so that
contaminates such as water or bodily fluids do not reach the
actuator elements or electrical connections. In another embodiment,
the plunge will create a vacuum in the hollow penetrating member to
aspirate bodily fluids and/or tissue for sampling such as in a soft
tissue biopsy procedure.
[0109] In the most preferred embodiment, the side port is located
on the penetrating member hub 525 at the end attachment point
[0110] Referring now to FIG. 7, a first embodiment of the present
invention, for example a penetrating introducer, generally
indicated as 200, comprises an actuator, such as the Langevin
actuator 100 described in FIG. 4, with the penetrating member 20 of
FIG. 5 being attached at a distal face 121 of the actuator. The
needle attachment fitting 128 is a threaded fitting, Luer taper,
compression fitting or the like, and couples hollow needle 130 to a
portion of distal face 121 such that it communicates with a distal
volume of continuous bore 126. Plunger handle 132 may be a
threaded, clamped, compressed or the like to bolt 116 so as to
immobilize plunger 12 of FIG. 6. The present invention is
sterilizable using such methods as steam sterilization, a sleeve,
gamma, ethylene oxide (ETO). For example, FIG. 6a depicts a
sterilization sleeve 115 for wires and housing used with the
present invention. The preferred material for the needle attachment
128 is a metal or a metal insert in a molded plastic. FIG. 6b shows
the Langevin actuator 100 with a possible configuration of the
battery & inverter compartment 117 attached to the end of the
actuator.
[0111] Returning to FIGS. 4 and 7, upon application of an external
AC current at a predetermined frequency to the at least one of
piezoelectric elements 114, the Langevin actuator 100 reactively
changes shape in a sinusoidal fashion such that the relative
position of distal face 121 with respect to say, a fixed position
of plunger handle 132 attached to and held in place by bolt 116,
changes by a predetermined displacement. Because the AC current is
a sinusoidal signal, the result of activating the piezoelectric
elements 114 is a sinusoidal, back and forth motion of the distal
face 121 of horn 110, and, subsequently, a back and forth motion of
needle 130, thereby reducing the force necessary for penetration
through tissue. As mentioned previously, the AC energization can be
provided directly from an AC source or from a DC source (e.g.,
onboard batteries) coupled to an inverter (e.g.,
oscillator/amplifier, etc.) which in turn is coupled to the
piezoelectric elements 114. The DC source is the more preferred
embodiment as wires and connections will need additional
sterilization features.
[0112] FIG. 7a depicts a similar invention as shown in FIG. 7 but
includes a penetrating member hub 525 with a side port SP connected
to the hollow needle 130. This configuration enables pressure
sensor to be mounted in the side port SP which once removed
provides for a catheter to be inserted or fluids removed. This is
likely the preferred embodiment when compared to FIG. 7 as the
entire active device will not be at risk for contamination since
the catheter or fluids do not traverse the actuator only the hollow
needle 130 which could be manufactured for single use.
[0113] Referring to FIG. 8, a supported introducer, generally
indicated as 201, is similar to the penetrating introducer 200 of
FIG. 7 additionally comprising support wings 111, existing for
example as a flat portion onto which a user can grasp, and
extending radially from an outer surface forming a mechanical zero
node of the horn 110, as described later with regard to FIG. 17. A
side port SP (not shown) could be 90 degrees clockwise or
counterclockwise from the support wings that may be a location for
providing access for aspirated sample retrieval, catheter insertion
etc.
[0114] In an alternate embodiment of the present invention, the
penetrating introducer 201 of FIG. 8 exists as a catheterization
introducer, generally indicated as 202, as shown in FIG. 9. In this
embodiment, rather than a plunger being introduced from a proximal
end of the device, a catheter 129 is introduced from the proximal
end of the device and is received through bore 126 as shown in FIG.
4, and may be passed through hollow needle 130. Upon having been
inserted into a patient, hollow needle 130 forms a subcutaneous
tunnel through which catheter 129 is introduced into the body. Upon
successful introduction, the actuator may be detached from hollow
needle 130 by decoupling attachment fitting 128 from the horn
110.
[0115] A more preferred embodiment 202b is shown in FIG. 9a where a
side port SP permits the introduction of the catheter 129 into the
present invention, rather than through the proximal end, as shown
in FIG. 9. This configuration enables pressure sensor to be mounted
in the side port SP which once removed enables a catheter to be
inserted or fluids removed near the distal face 121 of the device.
This is likely the preferred embodiment when compared to FIG. 9 as
the entire active device will not be at risk for contamination
since the catheter or fluids do not traverse the entire
actuator.
[0116] In the most preferred embodiment 202c is shown in FIG. 9b
where the side port SP located on the penetrating member hub 525
permits a pressure sensor to be mounted in the side port SP which
once removed provides entry of an instrument such as a catheter 129
to be inserted or fluids aspirated. This is likely the preferred
embodiment when compared to FIG. 9 as the entire active device will
not be at risk for contamination since the catheter or fluids do
not traverse the actuator only the hollow needle 130.
[0117] Now referring to FIG. 10a, an inner stylet, generally
indicated as 14, comprises an inner stylet handle 142 attached to a
proximal end of an inner stylet shaft 144. At a distal end of the
inner stylet shaft 144, opposite to the handle 142 is a sharpened
inner stylet tip 146. To support the inner stylet shaft 144, an
outer trocar tube, generally indicated as 15, shown in FIG. 10b
comprises a trocar attachment fitting 148 attached at a proximal
end of an outer trocar body 150, which is a tubular structure open
at opposite ends. The trocar attachment fitting 148 is hollow such
that outer trocar body 150 is disposed within it. Additionally, one
of the openings formed at opposite ends of the trocar body 150 is a
distal trocar opening 152, the outer walls of which form distal
trocar tip 154. As shown in FIG. 10c, inner stylet shaft 144 may be
slidably disposed within outer trocar body 150 with inner stylet
tip 146 extending beyond distal trocar tip 154. Together, the inner
stylet 14 of FIG. 10a and outer trocar tube 15 of FIG. 10b form a
structure similar to a trocar needle (e.g., a JAMSHIDI.RTM. biopsy
tool).
[0118] Referring now to FIG. 11, inner stylet 14 is slidably
disposed within bore 126 of Langevin actuator 100 of FIG. 4 and
outer trocar tube 15 of FIG. 10b, with outer trocar tube 15
attached to horn 110 to form a bone biopsy device, generally
designated as 300. Inner stylet 14 extends in a manner such that
handle 142 contacts bolt 116 when fully seated, with inner stylet
shaft extending from handle 142 through proximal opening 124,
through bore 126 and hollow portion of outer trocar body 150
finally terminating as inner stylet tip 146 at a location beyond
distal trocar tip 154. In this embodiment, when the at least one of
piezoelectric elements 114 of Langevin actuator 100 of FIG. 4 is
electrically actuated via electrical conductors 114b at a
predetermined frequency, motion in the form of compression and
expansion of the rings is transferred to an anti-node location at
the distal face 121 of horn 110. The motion is then transferred as
actuation of outer trocar tube 15 of FIG. 10b.
[0119] In an alternate embodiment, an advanced bone biopsy device,
generally indicated as 400, shown in FIG. 12, comprises all of the
elements of bone biopsy device 300 of FIG. 11, except that upon
electrical activation of Langevin actuator 100 of FIG. 4 at a
predetermined frequency, the motion is transferred as actuation of
inner stylet 14. To perform this function, the positioning of the
inner stylet shaft 14 of FIG. 10a and outer trocar tube 15 of FIG.
10b are inverted with respect to the configuration of FIG. 11. For
example, in the advanced bone biopsy device 400, outer trocar tube
15 is attached to bolt 116. Additionally, inner stylet 14 extends
in a manner such that handle 142 contacts distal face 121 of horn
110 when fully seated, with inner stylet shaft 144 extending from
handle 142 through distal opening 122, through bore 126 and hollow
portion of outer trocar body 150, finally terminating as inner
stylet tip 146 at a location beyond distal trocar tip 154.
[0120] While the previous embodiments have been described with
respect to a Langevin actuator 100 as the actuating mechanism, the
invention is not so limited. For example, as shown in FIG. 13, a
hollow tubular structure having a sharpened distal tip 513b of the
penetrating member 513 is attached at its proximal end 513a to an
Amplified piezoelectric actuator (APA) 510 forming an APA needle,
generally designated as 16. The amplified piezoelectric actuator
(APA) 510 comprises a frame 512, normally formed of a metal such as
brass or stainless steel, and a piezoelectric material 514
compressed within frame 512. An APA bore 526 may extend from a
distal face through piezoelectric material 514 and through a
proximal face 512a of frame 512. Hollow penetrating member 513, for
example a hypodermic needle, is attached to the distal face 512b of
frame 512, such that the hollow portion is concentrically aligned
with the APA bore 526. As shown in FIG. 14, APA needle 16 may be
disposed within a handle 518 forming an APA syringe, generally
designated as 500. Important to this embodiment is that a proximal
face 512a of frame 512 of amplified piezoelectric actuator (APA)
510 must be fixed as shown at 516 attachment point to an inner
portion of handle 518 such that the APA bore 526, hollow
penetrating member 513, a handle proximal opening 524 and handle
distal opening 521 form a continuous channel through which fluids
may pass into a patient. FIGS. 13a and 14a show alternate
embodiments 16b and 500b, respectively, with a detachable
penetrating member hub 525 enabling the single use penetrating
member with re-usable active motion handle where the penetrating
member hub 525 is described previously.
[0121] In operation, the piezoelectric material 514 expands during
the AC voltage cycle, which causes the frame's proximal and distal
faces 512a, 512b formed opposite of one another to move inward
toward each other. Conversely, when piezoelectric material 514
compresses during the opposite AC cycle, an outward displacement of
the frame's proximal and distal faces 512a, 512b away from one
another occurs. However, in the present embodiment, the proximal
face 512a of the frame is fixedly attached to body's 518 attachment
point 516 so that any movement in the piezoelectric material stack
will result in only a relative motion of distal face 512b and,
thereby, a motion of the penetrating member 513.
[0122] Two examples of applicable amplified piezoelectric actuators
(APAs) are the non-hinged type, and the grooved or hinged type.
Details of the mechanics, operation and design of an example hinged
or grooved APA are described in U.S. Pat. No. 6,465,936 (Knowles et
al.), which is hereby incorporated by reference in its entirety. An
example of a non-hinged APA is the Cedrat APA50XS, sold by Cedrat
Technologies, and described in the Cedrat Piezo Products Catalogue
"Piezo Actuators & Electronics" (Copyright.COPYRGT. Cedrat
Technologies June 2005).
[0123] Preferably, the APAs of the present invention are operated
at frequencies in the range of 100 Hz to 20 kHz, more preferably
100 Hz to 1 kHz.
[0124] Alternatively, the actuator of the present invention may be
a Cymbal actuator. For example, in FIG. 15, a Cymbal syringe,
generally indicated as 600, including a Cymbal actuator 610 which
comprises two endcaps 612 with the distal endcap 612b and proximal
endcap 612a with at least a piezoelectric element 514 formed
between the endcaps. The Cymbal syringe is centered on the Cymbal
bore 626. The endcaps 612 enhance the mechanical response to an
electrical input, or conversely, the electrical output generated by
a mechanical load. Details of the flextensional Cymbal actuator
technology is described by Meyer Jr., R. J., et al., "Displacement
amplification of electroactive materials using the Cymbal
flextensional transducer", Sensors and Actuators A 87 (2001),
157-162. By way of example, a Class V flextensional Cymbal actuator
has a thickness of less than about 2 mm, weighs less than about 3
grams and resonates between about 1 and 100 kHz depending on
geometry. With the low profile of the Cymbal design, high frequency
radial motions of the piezoelectric material are transformed into
low frequency (about 20-50 kHz) displacement motions through the
cap-covered cavity. An example of a Cymbal actuator is described in
U.S. Pat. No. 5,729,077 (Newnham et al.) and is hereby incorporated
by reference. While the endcaps shown in the figures are round,
they are not intended to be limited to only one shape or design.
For example, a rectangular Cymbal endcap design is disclosed in
Smith N. B., et al., "Rectangular Cymbal arrays for improved
ultrasonic transdermal insulin delivery", J. Acoust. Soc. Am. Vol.
122, issue 4, October 2007. Cymbal actuators take advantage of the
combined expansion in the piezoelectric charge coefficient d.sub.33
(induced strain in direction 3 per unit field applied in direction
3) and contraction in the d.sub.31 (induced strain in direction 1
per unit field applied in direction 3) of a piezoelectric material,
along with the flextensional displacement of the endcaps 612, which
is illustrated in FIG. 15. The design of the endcaps 612 allows
both the longitudinal and transverse responses to contribute to the
strain in the desired direction, creating an effective
piezoelectric charge constant (d.sub.eff) according to the formula,
d.sub.eff=d.sub.33+(-A*d.sub.31). Since d.sub.31 is negative, and
the amplification factor (A) can be as high as 100 as the endcaps
612 bend, the increase in displacement generated by the Cymbal
compared to the piezoelectric material alone is significant. The
endcaps 612 can be made of a variety of materials, such as brass,
steel, titanium or KOVAR.TM., a nickel-cobalt ferrous alloy
compatible with the thermal expansion of borosilicate glass which
allows direct mechanical connections over a range of temperatures,
optimized for performance and application conditions. The endcaps
612 also provide additional mechanical stability, ensuring long
lifetimes for the Cymbal actuators.
[0125] The Cymbal actuator 610 drives the penetrating member 513.
When activated by an AC current, the Cymbal actuator 610 vibrates
sinusoidally with respect to the current's frequency. Because
endcap 612a is fixed to an inner sidewall of body 518, when Cymbal
actuator 610 is activated, endcap 612b moves with respect to the
body in a direction parallel to the hypothetical long axis of the
medical device. Further, the displacement of penetrating member 513
is amplified relative to the displacement originating at
piezoelectric material 514 when it compresses and expands during
activation due in part to the amplification caused by the design of
endcaps 612. For example, the piezoelectric material 514 alone may
only displace by about 1-2 microns, but attached to the endcaps
612, the Cymbal actuator 610 as a whole may generate up to about 1
kN (225 lb-f) of force and about 80 to 100 microns of displacement.
This motion is further transferred through the penetrating member
513 as an amplified longitudinal displacement of 100-300 microns.
For cases requiring higher displacement, a plurality of Cymbal
actuators 610 can be stacked endcap-to-endcap to increase the total
longitudinal displacement of the penetrating member 513. FIG. 16
shows an alternate embodiment 600b with a detachable penetrating
member hub 525 enabling the single use penetrating member with
reusable active motion handle.
[0126] In alternate embodiments of the present invention, an
additional port opening is formed in communication with a channel
formed within the body of the actuator, for example a Langevin
actuator. In particular, FIGS. 17-19 are directed to these
alternate embodiments and it should be noted that for clarity
reasons, the handle 118 of the Langevin actuator is not shown in
these figures.
[0127] Because the port opening is provided so as to attach a means
for providing visual, audible or tactile feedback response (e.g.,
using any well-known detection mechanisms such as but not limited
to electrical, magnetic, pressure, capacitive, inductive, etc.
means) to indicate the successful penetration of the specific
tissue such as the epidural space, it must be formed at a location
which will be least detrimental to such means. In other words,
because the actuator vibrates at high frequencies, each point along
the actuator experiences a different displacement defined by a
standing wave. In FIG. 17, a displacement graph G1 represents a
standing wave having longitudinal displacements at points along the
length of a Langevin actuator operated at 38 kHz. As can be seen in
a displacement graph G1, two nodes having near zero displacement
exist at particular locations in the standing wave. The two node
("zero node" ZN) locations on the Langevin actuator LT are
therefore defined at a particular lengths along the Langevin
actuator. In the specific design shown in FIG. 17 the nodes on the
standing wave correspond to zero node, or locations having minimum
displacements on the Langevin actuator LT. The locations of the
zero nodes on the Langevin actuator LT are then located at a
proximal face (not shown) of the rear mass opposite to the distal
face 121. Line ZN defines the physical location of the other zero
node at which a side port SP should be located, preferably
centered, when formed in a Langevin actuator LT relative to second
zero node of the standing wave in displacement graph G1. In the
case shown in FIG. 17, the side port SP is formed at the horn 110
of the Langevin actuator LT, however a port opening is not
necessarily so limited. A port opening can be placed anywhere along
an actuator but a zero node location is preferred.
[0128] In a more preferred embodiment, FIG. 17a describes the side
port SP location on the zero node ZN of the penetrating member hub
525. In this embodiment, the design length includes both the needle
length and actuator length to achieve the zero node ZN on the
hollow needle 130 which includes length of penetrating member hub
525. A side port SP can be placed anywhere along hollow needle 130
but a zero node location on the penetrating member hub 525 is
preferred.
[0129] In FIG. 18a, a general side port configuration 700 of the
present invention is shown with a side port SP as the port opening
centered at a zero node location along the horn 110. Support wings
111 are also formed at a zero node to assist the clinician is
holding and stabilizing the device.
[0130] In a seventh embodiment of the present invention shown in
FIG. 18b, a first side port configuration 700a has a channel for
passing liquid, air or other materials comprises a continuous path
from the proximal opening 124 through bore 126 passing through a
distal opening (not shown) and extending through hollow needle 130
ending at a distal end 130a of the hollow needle which is open. In
this seventh embodiment, the channel is in communication with the
side port SP at a location along bore 126. Preferably, the side
port SP is located at such a location along the actuator forming
the first side port configuration 700a that acts as a zero node
upon activating the device to vibrate.
[0131] Alternatively, as shown in an eighth embodiment of the
invention in FIG. 18c, a second side port configuration 700b has a
channel for passing liquid, air or other materials comprises a
continuous path located on the hollow needle 130 penetrating member
hub 525. In this eighth embodiment, the channel is in communication
with the side port SP at a location along penetrating member hub
525. Preferably, the side port SP is located at such a location
along the entire length (actuator and penetrating member) forming
the second side port configuration 700b that acts as a zero node
upon activating the device to vibrate. In a secondary side port SP
located on the actuator an indicator such as a light emitting diode
1026 can be attached and connected to the electronics to indicate a
visual loss of resistance.
[0132] Alternatively, as shown in an eighth embodiment of the
invention in FIG. 18d, a second side port SP configuration 700c has
a small bore 126a for passing liquid, air or other materials
located at zero node ZN to and from the hollow needle 130.
[0133] In a ninth embodiment of the present invention shown in FIG.
19, a feedback capable reduction of force tool 800 is provided. By
way of example only, tool 800 comprises a means for providing
tactile feedback response via a conventional loss of resistance
syringe PA3 having a biasing element 11 with a plunger or balloon
(e.g., elastomer device) or any other device that creates pressure
then detects or measures pressure change. This device is coupled at
a port location, preferably a side port SP located, via, by way of
example only, a Luer Taper, male/female connector, screw-type
connector, and preferably centered, at a zero node location. The
tool 800 also includes an indicator in communication with the
actuator 700 such as, but not limited to, an audible indicator,
tactile indicator, or visual (e.g., deflation, optical, etc.).
[0134] In a most preferred embodiment of the present invention
shown in FIG. 19a, a feedback capable reduction of force tool 800
is located on the hollow needle 130 at a zero node ZN on the
penetrating member hub 525.
[0135] Another embodiment described in FIG. 19b, a possible
pressure sensor feedback system 1020 containing a small pumping
mechanism equipped with a pressure or flow sensor to meter the
amount of fluid being moved, a reservoir 1021 mounted on a base
1024. The pump fills with saline and connect via flexible tubing
1022 via an attachment fitting 1023 to the side port SP of the
penetrating member. When loss of resistance (LOR) is detected, the
electronic control system will close a switch and an indicator such
as a light emitting diode (LED) (not shown) located on the side
port SP of the actuator will turn-on indicating loss of resistance.
The electronics control system at this point will turn the actuator
off so that forward motion ceases. In additional embodiment,
besides the visual signal, an audible signal a `beep` could be
incorporated into the pump system.
[0136] By way of example only, the following is an exemplary method
of using the present invention, whereby a clinician uses the
present invention for an epidural procedure. When performing an
epidural procedure, the clinician first fills syringe PA3 with a
fluid, such as a saline solution or air. The clinician then inserts
the front portion 9 of the syringe into the side port SP of the
actuator 700b. Upon electrically activating the actuator, the
clinician holds actuator 700b with a first hand while pressing the
distal end 130a of the hollow needle against a patient's back. The
clinician continues to provide forward momentum, while also
providing a biasing force against biasing element 11, advancing
hollow needle 130. With continued forward momentum, the hollow
needle punctures the supraspinous ligament, the instraspinous
ligament, and the ligamentum flavum (see FIG. 7, for example). Upon
puncturing the ligamentum flavum, the distal end 130a of the needle
enters the epidural space at which point there is a pressure drop
from the biasing element 11 to the opening at the distal end 130a.
The pressure drop allows for the solution to be ejected from the
opening at the distal end 130a, and the continued biasing of the
biasing element 11 combined with the loss of volume of saline
results in a loss of resistance (LOR) against the clinician's thumb
and a visibly identifiable motion of the biasing element 11. When
the biasing element moves due to this lack of resistance, the
clinician quickly identifies that the epidural space has been
successfully reached and quickly stops forward momentum of the
actuator. Additionally, because the activation of the actuator
results in a vibration of the needle 130, the clinician does not
need to provide such a high penetration force and can quickly react
to stop himself/herself before advancing the needle beyond the
epidural space.
[0137] It should be further noted that it is within the broadest
scope of the present invention to include syringes or other
mechanisms which provide automatic biasing, such that the clinician
does not have to apply a biasing force against the biasing element
11 prior to entry into, for example, the epidural space. In
particular, the automatic biasing force (implemented, for example,
via a spring, an elastomer, or any other well-known biasing
mechanism such as, but not limited to, those described in U.S.
Patent Publication No. 2007/0142766 (Sundar, et al.)) maintains an
equal resistance as the needle is moved through the supraspinous
ligament, the instraspinous ligament, and the ligamentum flavum.
Upon entry into the epidural space, the biasing force is no longer
resisted and this can be manifested in a variety of ways to the
clinician, but not limited to, movement of the biasing element, or
any other visual, audible or tactile indication using any
well-known detection mechanisms such as but not limited to
electrical, magnetic, pressure, capacitive, inductive, etc. means.
For example, a pressure signal indicative of a loss of solution
resistance automatically cuts off power to the driver actuator
(e.g., piezoelectric elements, voice coil, solenoid, etc.).
[0138] While feedback means have been coupled to the side port SP,
the invention is not so limited to feedback means. Any device may
be coupled to a port location of the actuator, or ideally at the
side port SP location even those devices simply being a means for
providing or removing liquid, gas or other material such as a
conventional syringe.
[0139] While the above-described embodiments of the present
invention are made with respect to a handheld medical tool having a
vibrating penetrating member and utilizing a Langevin actuator,
Cymbal actuator, or APA for actuation, as mentioned earlier, the
present invention is not limited to these actuator assemblies.
Generally, any type of motor comprising an actuator assembly,
further comprising a mass coupled to a piezoelectric material, or a
voice coil motor, or solenoid, or any other translational motion
device, would also fall within the spirit and scope of the
invention. Furthermore, where the actuator assembly comprises a
mass coupled to a piezoelectric material, the actuator assembly
having a geometry which, upon actuation, amplifies the motion in a
direction beyond the maximum strain of the piezoelectric material,
would also fall within the spirit and scope of the present
invention.
[0140] FIG. 20a depicts an alternative embodiment 900 of the
present invention using a voice coil for the driving actuator
rather than piezoelectric elements. Voice coil actuator (also
referred to as a "voice coil motor") creates low frequency
reciprocating motion. The voice coil has a bandwidth of
approximately 10-60 Hz and a displacement of up to 10 mm that is
dependent upon applied AC voltage. In particular, when an
alternating electric current is applied through the conducting coil
902, the result is a Lorentz Force in a direction defined by a
function of the cross-product between the direction of current
through the conductive coil 902 and magnetic field vectors of the
magnetic member 904. The force results in a reciprocating motion of
the magnetic member 904 relative to the coil support tube 906 which
is held in place by the body 910. With the magnetic member 904
fixed to a driving tube 912, the driving tube 912 communicates this
motion to an extension member 914 which in turn communicates motion
to the penetrating member 20.
[0141] A first attachment point 916a fixes the distal end of the
coil support tube 906 to the body 910. A second attachment point
916b fixes the proximal end of the coil support tube 906 to the
body 910. The conducting coil may be made of different
configurations including but not limited to several layers formed
by a single wire, several layers formed of different wires either
round or other geometric shapes. In a first embodiment of the
conducting coil shown in FIG. 20a, a first layer of conductive wire
is formed by wrapping the wire in a turn-like and spiral fashion
and in a radial direction around the coil-support tube with each
complete revolution forming a turn next to the previous one and
down a first longitudinal direction of the coil support tube. After
a predetermined number of turns, an additional layer is formed over
the first layer by overlapping a first turn of a second layer of
the wire over the last turn of the first layer and, while
continuing to wrap the wire in the same radial direction as the
first layer, forming a second spiral of wiring with at least the
same number of turns as the first layer, each turn formed next to
the previous one and in a longitudinal direction opposite to that
of the direction in which the first layer was formed. In this
embodiment, additional layers may be added by overlapping a first
turn of each additional layer of the wire over the last turn of a
previous layer and, while continuing to wrap the wire in the same
radial direction as the previous layer, forming an additional
spiral of wiring with at least the same number of turns as the
previous layer, each turn formed next to the previous one and in a
longitudinal direction opposite to that of the direction in which
the previous layer is formed.
[0142] An alternative voice coil embodiment 900b is shown in FIG.
20b. In particular, in this alternative, the locations of the
magnetic member 904 and conductive coil 902 are switched. In other
words, the conductive coil is wrapped around and attached to the
driving tube 912 and the magnetic member 904 is located along an
outside radius of the coil support tube 906.
[0143] An electrical signal is applied at the conductive attachment
sites 918 and 920 and causes the formation of the Lorentz force to
form in an alternating direction that moves the conductive coil 902
and extension member 914 reciprocally along the longitudinal axis
of the device. The conductive coils are physically in contact with
the driving tube in this embodiment.
[0144] FIG. 20c depicts another embodiment of the present invention
using a voice coil type actuating mechanism and is of a different
configuration than that used in FIGS. 20a and 20b. For example, in
this alternative embodiment, a voice-coil actuating mechanism is
substituted with a dual-coil actuating mechanism and as a result of
this substitution, the magnetic member 904 of the voice-coil is
replaced with second conductive coil 922. In other words, the
second conductive coil 922 is wrapped around and attached to the
driving tube 912 and the first conductive coil 902 is located, as
in the first preferred embodiment, along an outside radius of the
coil support tube 906. In a first embodiment of the configuration
of FIG. 20c, the inner coil 922 is conducting direct current DC and
the outer coil is conducting alternating current AC. In an
alternative embodiment, the inner coil is conducting alternating
current AC and the outer coil is conducting direct current DC. In
an additional embodiment, both the inner coil and the outer coil
are conducting alternating current AC.
[0145] In all of the voice coil actuator configurations described,
springs may be used to limit and control certain dynamic aspects of
the penetrating member 20. FIG. 20d depicts another variation of
the voice coil actuator mechanism of the tenth embodiment using
springs, Medical Tool using solenoid actuator 1000. As with the
other voice coil embodiments using coils, the basic principle of
actuation is caused by a time varying magnetic field created inside
a solenoid coil 1002 which acts on a set of very strong permanent
magnets. The magnets 1004 and the entire penetrating member 20
assembly oscillate back and forth through the solenoid coil 1002.
The springs 1014 (such as those shown in FIG. 20d) absorb and
release energy at each cycle, amplifying the vibration seen at the
penetrating member 20. The resonant properties of the device can be
optimized by magnet selection, number of coil turns in the
solenoid, mass of the shaft, and the stiffness of the springs.
[0146] From the above description, it may be appreciated that the
present invention provides significant benefits over conventional
medical devices. The configuration of the actuating means described
above, such as embodiments comprising a Langevin actuator, Cymbal
actuator, or an APA, accommodates the use of piezoelectric
actuating members in a medical instrument by enabling the
displacement of the penetrating sharps member or needle to such
frequencies that cause a reduction of force needed for penetrating
through tissue during procedures such as bone biopsy, epidural
catheterization or vascular entry. Electrical signal control
facilitated by an electrically coupled feedback system could
provide the capability of high oscillation rate actuation, control
over penetration depth, electrical cut off (faster response than
human) and low traction force for these procedures. FIG. 21
depicts, by way of example only, an electrical cut off
configuration. A pressure transducer PT monitors the pressure from
the penetrating member 20 or of a fluid in communication with the
tissue through the present invention. While the penetrating member
20 is penetrating tissue, the pressure detected by the pressure
transducer PT is high and the switch S is normally closed. As soon
as there is a drop in pressure (indicating passage through the
final layer of tissue), the pressure transducer PT signal opens the
switch S, thereby cutting off power to the medical tool. In
addition, or a visual, audible or tactile indicator immediately
activates warning the operator of sufficient passage by the
penetrating member 20 and power cut off. It is within the broadest
scope of the present invention to encompass a variety of power cut
off configurations, including solid state switching and/or digital
controls.
[0147] Another electrical power cut off implementation detects a
forward motion of the biasing element 11 discussed previously. In
particular, once the penetrating member 20 passes through the last
tissue layer, pressure on the biasing element 11 is relieved and
the incremental movement of the biasing element 11 into the body 10
is detected by a sensor which instantly opens the switch S and
thereby cuts off electrical power to the present invention.
[0148] Additionally, the feedback control of the electronics
enables the device to be vibrated in such a way that the force is
also reduced as the penetrating member is retracted from the living
being as would be necessary in bone biopsy after the tissue is
extracted.
Additional Embodiments
[0149] Additional embodiments of the present invention are
illustrated in FIGS. 22-31.
[0150] Feedback Means Using Electromechanical Properties
[0151] As discussed above, a medical device for penetrating living
being tissue can include a driving actuator for converting
electrical energy into reciprocating motion when energized. The
driving actuator can include a distal end and a first channel
extending to the distal end, and a penetrating member can be
coupled to the distal end of the driving actuator. The medical
device can include a feedback subsystem that detects any change of
electromechanical properties related to the operation of the
penetrating member. For example, the feedback subsystem can be
utilized for: (i) indicating to an apparatus operator a different
type of tissue has been contacted by said penetrating member;
and/or (ii) automatically controlling force being applied to said
penetrating member.
[0152] FIG. 22 provides a general method of implementing the
feedback subsystem of the present invention. Using a predetermined
association of electromechanical properties regarding various
tissues (e.g., fat, muscle, cartilage, bone, etc.), as described
with regard to FIG. 23, the feedback subsystem includes a sensor
for detecting system/device changes as the sharps member (e.g.,
needle) penetrates tissue and wherein the sensor generates a signal
characteristic of the electromechanical property being monitored.
The sensor (e.g., impedance analyzer, such as the Hewlett Packard,
HP 4192A) feeds this signal to a microcontroller that references a
look-up table to determine the material that the sharps/penetrating
member 20 is currently passing through. The microcontroller can
drive a display or other indicators or alerts for informing the
operator of the present invention, for example the use of Langevin
actuator 100, just what the sharps/penetrating member 20 is
currently cutting. One alternative is for the microcontroller to
deenergize the penetrating introducer 200, if necessary.
[0153] FIG. 23 shows data which demonstrates an exemplary
methodology for determining characteristic electromechanical
properties (e.g., system/device impedance, system/device phase lag,
system/device conductivity, density variability, etc.) to be used
for generating a "look-up" table or other association of tissue
with the changing electromechanical property as part of the
feedback subsystem. By way of example only, a 1.5 inch long,
hollow, 3 faceted Trocar needle (vibrating reference member) is
mounted on a bolted Langevin transducer. The resonance frequency of
the system in air is .about.47 kHz. The tip is inserted 5 mm into
different test media with a variety of densities. FIG. 23 is a plot
of the amplitude of the impedance (by way of example only) curve as
a function of frequency. The peak is the anti-resonant frequency.
The dip downward to the left is the resonant frequency. The upper
curve is the needle/transducer assembly in air. The lower curves
show a reduction in amplitude, and slight shift in anti-resonant
frequency, as the needle is inserted into media of increasing
stiffness (e.g., sponge, dense foam, apple, potato). The lowest
curve shows the result when the needle was inserted .about.1 inch
into the potato. These shifts in amplitude and frequency (and other
potential measurements such as phase lag, resistance and density)
provide various electromechanical (EM) properties that can be used
for distinguishing between different tissues, and also the depth of
insertion.
[0154] FIG. 24 provides an exemplary block diagram of a feedback
subsystem 2400 for use in the present invention. The
microcontroller 2402 may comprise a look-up table in an internal
memory generated in accordance with that described with regard to
FIG. 23. Depending on which EM property is being monitored (e.g.,
device impedance, device conductivity, device phase lag, density
variability, etc.) a corresponding sensor feeds back the
corresponding EM property signal to the microcontroller 2402 which
uses the process of FIG. 22 to drive indicators or the display to
alert the device operator as to the tissue that the
penetrating/sharps member 20 is currently passing through. The
microcontroller 2402 also controls the device energization via
drive electronics 2404. It should be noted that embodiments, such
as penetrating introducer 200 may be powered from an external AC
power source or batteries. In either case, power to the penetrating
introducer 200 can be immediately controlled or even interrupted
when particular tissue penetration is detected.
[0155] As discussed above, it is within the broadest scope of the
present invention to encompass a variety of feedback
configurations, including solid state switching and/or digital
controls. Additionally, the present invention comprises sensors for
providing feedback, either visually, audibly, or by tactile
response, using a variety of detection mechanisms (such as, but not
limited to, electrical, magnetic, pressure, capacitive, inductive,
etc. means) to indicate successful penetration of various tissues,
or of voids within the body so that the clinician is aware of the
tissue being passed through by the sharps member. Additionally, the
feedback control of the electronics enables a device, such as
penetrating introducer 200 to be vibrated in such a way that the
force is also reduced as the sharps member is retracted from the
living being. Even pressure transducers can be coupled on or
adjacent the sharps member where pressure of the distal tip of the
sharps member against the tissue being passed through is
transferred from the distal tip through the device body for EM
property detection.
[0156] Thus, an additional embodiment of a medical device, such as
penetrating introducer 200 in FIG. 4, for penetrating living being
tissue can include a driving actuator, such as Langevin actuator
100. The driving actuator can convert electrical energy into
reciprocating motion when energized. The driving actuator can
include a distal end such as distal face 121 and a first channel,
such as bore 126 extending to the distal end. The device can
further include a penetrating member 20 that is coupled to the
distal end of the driving actuator 100.
[0157] Additionally, the device 200 of FIG. 4 can include a
feedback subsystem 2400 as shown in FIG. 24. The feedback subsystem
2400 can detect any change of electromechanical properties related
to the operation of the penetrating member. By detecting any change
in electromechanical properties as discussed above, the subsystem
can indicate to an apparatus operator that a different type of
tissue has been contacted by said penetrating member 20 via forces
that work against the actuators ability to reciprocate, and cause
changes in electromechanical properties. Alternatively, by
detecting any change in electromechanical properties, as discussed
above, the subsystem 2400 can automatically control a force being
applied to said penetrating member. For example, the force required
for penetrating tissue using said penetrating member can be varied
by automatically controlling a frequency at which the device
actuates.
[0158] In an embodiment, the subsystem 2400 can monitor at least
one electromechanical property such as phase lag in a control
signal of said apparatus (for example phase lag between a voltage
and current signal magnitude), a conductivity change detected by
the device (for example, conductivity of surrounding tissue
adjacent to a sharps member of the device), a voltage change in a
control signal of said apparatus (for example, a voltage change
detected by a force sensor upon penetration of a sharps member of
the device into a cavity such as the epidural space).
[0159] As discussed above, devices described herein can include one
or more of several types of actuators. In an embodiment, the device
can include at least one piezoelectric element such as
piezoelectric element 114. The piezoelectric elements can convert
electrical energy into oscillatory motion when they are
energized.
[0160] A device, such as device 200 of FIG. 4, for use with
subsystem 2400 can include a second channel, such as that extending
from an opening similar to sideport SP of FIG. 9b, having a first
end in communication with said first channel 126 of FIG. 9a and a
second end positioned at an exterior surface of the actuator. This
second channel is similar to the channel extending from opening
2502 in FIG. 26c. The first channel 126 of the device 200 can
extend through the device's penetrating member 130. A third channel
124 can extend through at least one piezoelectric element. The
first and third channels can be aligned. The device's anchor/rear
mass 112 can have a fourth channel 124 that extends therethrough
along a longitudinal axis of the anchor. The fourth channel 124 can
be aligned with the first 126 and third channels to form a
continuous channel through the actuator. The first channel 126 can
extend through a portion of the penetrating member.
[0161] As discussed above, the penetrating member of the
embodiments described herein can be one of a hypodermic needle,
catheterization needle, Tuohy needle, bone biopsy trocar, spinal
needle, nerve block needle, trocar access ports and interventional
radiology needle. As discussed above, the actuator of the
embodiments described herein can be a Langevin actuator, such as
Langevin actuator 100. As discussed above, an exterior surface of
the actuator can comprise a side port, such as sideport SP of FIG.
18a for providing fluid communication with, or passage of a
catheter within a penetrating member such as penetrating member
130.
[0162] In an embodiment, a device such as device 2599 for use with
subsystem 2400 can further include a force sensor 2522 in
mechanical communication with an actuator 2500, as shown in FIG.
25c and described in more detail below. The force sensor 2522 can
also be in electronic communication with the feedback subsystem for
activating said feedback subsystem. In one embodiment, a separator
mass (not shown) can be formed between the force sensor and the
actuator. In one embodiment, the force sensor is a piezoelectric
ring adjacent to a proximal end of the actuator's rear mass and
formed between the rear mass and an outer handle in which the
actuator is completely or partially disposed.
[0163] As discussed above, for example with respect to FIGS.
20a-20c, the driving actuator usable with feedback subsystem 2400
can include a voice coil 902/906/904. The voice coil can be coupled
to the penetrating member 20. The voice coil can convert electrical
energy into oscillatory motion when it is energized. The driving
actuator can be a pneumatic or a fluidic actuator (not shown).
Accordingly the feedback subsystem 2400 can be in electrical
communication with a voice coil, pneumatic or fluidic actuator.
[0164] As discussed above, a method for reducing the force needed
to penetrate living being tissue is provided, and is generally
illustrated as a flow chart in FIG. 22. While the operator can
manually control the force of the medical device against tissue,
the force can be controlled, and/or reduced, based on the tissue
being encountered during the insertion of a sharps member that is
reciprocated. The method can include the step of establishing
characteristic electromechanical property changes of a vibrating
reference member having a sharps member that passes through various
tissues that correlates said changes with particular tissues. The
characteristic electromechanical property changes can be
established by correlating changes within a single
electromechanical property, such as tracking impedance magnitude
vs. time, or between several electromechanical properties such as
comparing each of impedance magnitude and penetration force vs.
time. Such changes can be gathered, stored and analyzed, such as in
the graphs shown in FIG. 23 and FIGS. 29-31.
[0165] Particular changes and/or comparison of changes can be
correlated to a particular event and established as a predetermined
characteristic of electromechanical property or properties. For
example, empirically gathered data can be stored as a predetermined
value or predetermined values in a database and that is accessible
by a feedback system (such as that described in embodiments
herein). As the subsystem gather signals and uses or stores the
gathered signal as data representative of electromechanical
properties of a reciprocating device in operation, the gathered
electromechanical property or properties (or changes within or
between the properties), can be compared to the characteristic or
predetermined values stored on the database. In other words, the
real-time electromechanical properties can be correlated to an
event which is known, based on empirical results, to a particular
event. For example, the subsystem can gather data, compare the data
to values on a database representative of a known event, such as
penetration through particular tissue, for example penetration into
the epidural space, and the subsystem can respond based on whether
the real-time collected data matches the predetermined data within
a predetermined error value.
[0166] Continuing with a description of the method described in
FIG. 22, in some embodiments, it includes a "start" step 2202 of
reciprocating the sharps member against the living being tissue
using a reciprocating actuator that converts electrical energy to
reciprocating motion. The sharps member can be reciprocated by
providing power to an actuator, such as Langevin actuator 100,
coupled to the sharps/penetrating member/introducer 20, such as
described in steps 2202-2204. The method can include the step of
detecting a change in the characteristic electromechanical property
as described above. The step of detecting a change in the
characteristic electromechanical property can be performed by the
feedback subsystem 2400, based on controlling software that
includes a predetermined threshold change to which the measured
electromechanical properties measured in step 2206 are compared.
Thus, the method can include the step 2208 of referencing a
database that contains predetermined values corresponding to
electromechanical properties or change thereof that are
representative a particular event, particular tissue, or particular
property of a material that the device's penetrating member is in
contact with.
[0167] The subsystem can be programmed to perform step 2210 of
comparing the detected electromechanical property (or properties),
or change in electromechanical property (or properties) against
said the predetermined correlation. In step 2210, for example, the
subsystem can determine whether the measured input value or values
gathered in step 2206 matches a reference parameter. Such a
comparison can be based on known statistical algorithms for
comparing gathered data with stored corresponding data and can be
performed by a microprocessor controlled by the software.
[0168] Depending on the results of the comparison, the method can
perform a repeat of step 2206 or continue to step 2212. If, for
example, the feedback subsystem determines that a measured
electromechanical property, or change thereof, does not match a
corresponding characteristic of the property stored in the
database, the subsystem can proceed by repeating step 2206 and
again measure an updated electromechanical property. Otherwise, the
method can include the step 2212 of sending a signal to an output
device, for example, to indicate to an operator of an embodiment
described herein the type of tissue that is being currently
encountered by, for example, the sharps member, based on the change
in the characteristic electromechanical property. In one
embodiment, the step of indicating to an operator comprises
displaying or informing the operator of an identity of the tissue
being currently encountered by said sharps member.
[0169] The method can include the step of automatically controlling
or modifying the force being applied to said sharps member. In one
embodiment, the step of automatically controlling the force being
applied includes de-energizing the sharps member as shown in step
2216. In one embodiment, the step of automatically controlling the
force being applied includes maintaining or changing a frequency at
which sharps member is reciprocated as in step 2214.
[0170] As discussed above, the method described in the flowchart of
FIG. 22 can be used for the detecting of the passage of the
penetrating member through living being tissue. However, the
feedback subsystem can include visual or tactile response
indicators. For example, in an embodiment, the step of detecting
the passage of the penetrating member through the living being
tissue can include the movement of a plunger within a
fluid-containing syringe that is in fluid communication with a
channel within said penetrating member, such as via the sideport SP
in communication with first channel 126. In other words, the
syringe can be in electrical communication with the feedback
subsystem and can provide the subsystem with electronic signals
corresponding to movement of the plunger or a pressure loss within
the syringe to complement the other data, such as electromechanical
characteristics, that can be used for sensing a corresponding
event.
[0171] Additionally, a sensor, such as a pressure transducer, blood
flow detector, thermocouple can be used to sense fluid pressure
within the sharps/penetrating member of the device, and can be in
electronic communication with the feedback subsystem to complement
the other gathered data, such as electromechanical characteristics.
For example, in one embodiment, the step of detecting the passage
of the penetrating member includes the use of at least one sensor
that monitors at least one of a characteristic electromechanical
property. The at least one sensor can be in communication with a
channel of said penetrating member. The at least one sensor can
provide an output that controls the feedback subsystem which can
control the operation of a controller or switch that provides
electrical energy to said reciprocating actuator. In one
embodiment, the reciprocating actuator caused to reciprocate in the
disclosed method can be a Langevin actuator that includes a horn
section formed of a first portion detachably connected to a second
portion as described below.
[0172] Transducer, Needle, Feedback and Control Design for Reduced
Penetration Force
[0173] In some embodiments, the actuators described herein can be
operated at various frequencies, including ultrasonic frequencies
as discussed above. For example, the actuators can be operated to
actuate at a frequency, or various frequencies in the range of
19-50 kHz, 20-25 kHz, 21-30 kHz, 21-24 kHz, 24-30 kHz, 28-35 kHz,
and 40-50 kHz. The medical device can also be provided with driving
voltages of 100-500 V.sub.pp-, 100-200 V.sub.pp, 250-450
V.sub.p
[0174] As shown in FIGS. 25a-c, in an embodiment, the invention
includes a device, such as a medical device for penetrating through
living being tissue. The device can include an actuator 2500, such
as a Langevin transducer. The actuator 2500 can include a
displaceable member 2510, such as a horn capable of focusing
resonating energy provided by a piezoelectric stack portion 2514.
The displaceable member can be formed of a first portion 2510a
detachably connected to a second portion 2510b, a rear mass 2512,
and the piezoelectric stack 2514 which is formed between the
displaceable member 2510 and the rear mass 2512. The device can
also include a sharps member 2520 which is coupled to a distal end
2515 of the second portion 2510b. The device can also include an
electrical power feedback subsystem (not shown in FIGS. 25a-c),
such as the feedback subsystem 2400 described above, for
automatically controlling the power to the actuator based on a
sensed condition. One reason that the displaceable member 2510
includes a first portion detachably secured to the second portion
is so that a large portion of the actuator can be reused and the
second section 2510b can be disposed of or sterilized for repeated
use. Particularly, the second section 2510b can be acoustically
matched to function, in conjunction with portion 2510a,
substantially as a single piece horn. Were the device to include a
single piece horn instead of a multi-section horn, it might not be
possible for the actuator to be reusable as it could come into
contact with bodily fluid and would completely require
sterilization (which could potentially damage the piezoelectric
stack).
[0175] The second portion 2510b can function to accept the sharps
member 2520, such as a needle, so that can be secured permanently.
The sharps member 2520 can be secured to the second portion 2510b
prior to the second portion being releasably secured to the first
portion 2510a. Alternatively, the sharps member 2520 can be secured
to the second portion 2510b after the second portion has been
releasably secured to the first portion 2510a. The second portion
2510b can be configured to accept a sharps member 2520 directly at
the second portion's distal end. The second portion 2510b can be
configured to accept a hub (such as the hub of a disposable
needle), and become detachably connected to the hub. In other
words, a hub can be detachably connected to the second portion
2510b such that the hub is disposed between the second portion
2510b and a sharps member.
[0176] Piezoelectric elements 2514a, 2514b can comprise annular
piezoelectric elements. When attached to one another using methods
known in the art, the piezoelectric elements form a channel through
which a shaft portion (not visible) of the horn/displaceable member
2510 extending proximally from the first portion 2510a is passed
when assembling the actuator. The shaft portion mates with rear
mass 2512 via male threads on an end portion of the shaft that
match with female threads in the rear mass 2512. The piezoelectric
stack 2514 is configured to be pre-stressed due to being compressed
by the first portion 2510a and rear mass 2512 upon threading the
shaft portion into the corresponding threaded portion of the rear
mass.
[0177] Because lower acoustic impedance transfers energy more
efficiently, the actuator 2500, for example a Langevin transducer,
must include acoustically matched components for rear mass 2512,
piezoelectric stack 2514, first portion 2510a and second portion
2510b. For example, horn 2510 and rear/back mass 2512 are
configured such that when second portion 2510b of the horn is
attached to first portion 2510a, heating at, for example, the
proximal interface 2525 is kept to a minimum. Energy lost to
heating can be caused by the use of a conventional needle hub that
has not been configured to ultrasonically actuate when attached to
first portion 2510a. Such an energy loss can serve to reduce
displacement at the tip of sharps member 2520. Additionally, second
portion 2510b can be configured to be of certain dimensions. For
example, second portion 2510b can have a length of about 0.760''
and a width of 0.313'', however such dimensions do not limit the
configuration. Additionally, second portion 2510b should include a
channel through which fluids such as medications or bodily fluids,
or solids such as a catheter tube can be passed.
[0178] In one embodiment, the density of the horn can be less than
the density of the rear mass. In one embodiment, the first portion
2510a of the horn and the rear mass can be the same material and
the second portion 2510b of the horn can be a different material
that the second portion 2510b of the horn. For example, rear mass
2512 and first portion 2510a can be made of titanium while the
second portion 2510b of the horn can be made of stainless steel
(such as 304 stainless steel) or aluminum (such as 7075 T6
aluminum). Second portion 2510b can also be polymer, but must be
capable of accepting ultrasonic energy without failing. Second
portion 2510b should be configured to be releasably attached to
2510a, but should not be capable of loosening simply by activating
the device. The components of actuator 2500 can be acoustically
matched such that, for example, upon reciprocating at frequencies
between 19 kHz-25 kHz, temperature does not rise above 60.degree.
C. at a metal-metal interface. As shown in FIG. 25c, the medical
device can include a force sensor 2522 disposed at a proximal end
of the driving actuator. The force sensor 2522 can include a
piezoelectric ring. The force sensor can be a compact force sensor
integrated into a handpiece 2518 in which the actuator is
completely or partially disposed. The force sensor can include a
non-activated (i.e., non-actuating or sensing) piezoelectric stack
comprised of a plurality of piezoelectric rings. A separator mass,
such as a steel separator mass, or in the case of the Langevin
transducer, the rear-mass, can be formed between piezostack 2514
and sensing stack 2518. As the device is brought into contact with
an opposing force, such as tissue, the opposing force can be
measured by the force sensor as shown in FIG. 30.
[0179] The actuator can be disposed in a volume defined by the
handpiece 2518. A gap 2526, which is a portion of the volume
defined by the handpiece, can separates the handpiece and the
actuator from one another, either partially or completely, can be
filled with a vibration damping material such as silicone. The
vibration damping material can be used to secure the actuator and
to minimize the transfer of vibration caused by activation of the
actuator on the user gripping the handpiece 2518.
[0180] As discussed above, the device can include a feedback
subsystem. The feedback subsystem can be capable of detecting
electromechanical properties. For example, feedback subsystem can
include a phase angle detector for detecting passage of a distal
end of the sharps member 2520 into, for example the epidural space
of a living being or for detecting changes in device operation
conditions as the device is exposed to various media. Detection can
be based on a measured phase lag, or change in the measured phase,
of a control signal of the medical device.
[0181] In an embodiment, the feedback subsystem can include a
voltage detector for detecting passage of the distal end of said
penetrating member into the epidural space based on a voltage of a
control signal of said medical device. In one example, the feedback
subsystem can correlate abrupt changes in phase angle (as shown in
FIG. 29) and abrupt changes in voltage generation from the force
sensor (as shown in FIG. 30) to stored values that correspond to an
event, such as a known event, such as penetration into the epidural
space or the filling of the sharps member with cerebral spinal
fluid upon penetration into the subarachnoid space. The feedback
subsystem 2400, upon comparing the measured values with the stored
values, can automatically adjust the power delivery to the
actuator. One example of the feedback subsystem 2400 is shown in
FIG. 28 which provides different detail than the subsystem shown in
FIG. 24.
[0182] As shown in FIGS. 26a-c, the second portion 2510b includes a
channel 2504 disposed therein. The channel 2504 can be formed in
communication with at least two openings 2501, 2502 formed on an
outer surface of the second portion 2510b. Opening 2502 can be
formed by machining a flat surface by removing material from a
corner of an outer grippable portion 2509, which has a polygonal
cross section, and then drilling into the flat surface. The second
portion 2510b can include a third opening 2503 that is not in
communication with the at least two openings. In other words,
opening 2503 can be formed so as to accept a distal end of the
first portion 2510b. The channel 2504 comprises a first section
that, at opening 2501, accepts a proximal end of the sharps member
2520. The channel 2504 can include a second section that, at
opening 2502 can accept material capable of being introduced to an
inner volume of the sharps member (e.g., fluids, medicines,
catheters, or the distal end of a syringe). The second portion
2510b can be configured, with or without the sharps member
attached, as a disposable or single-use item. In other embodiments,
the sharps member can be configured to be detachably secured to the
second portion 2510b, such that the sharps member can be disposed
of after use, and the second portion can be reused, for example,
after undergoing sterilizing in an autoclave.
[0183] The channel that communicates with the two openings can
include a bend such that a first section of the channel in
communication with opening 2501 and second section of the channel
in communication with opening 2502 are separated by an angle
.alpha.. Angle .alpha. should not be so great so as to prevent the
insertion of a catheter through the second opening, can traversal
of the catheter through the channel, and the catheter's exit
through the first opening 2501. For example, the bend angle .alpha.
can be greater than about 0.degree. to about 90.degree. from an
axis that runs through the center of the first opening as shown by
the vertical dashed line in FIG. 26c. Preferably, the bend angle
.alpha. can be about 45.degree. to about 55.degree..
[0184] In order to, among other things, prevent bodily fluids,
medications or other materials from coming into contact with the
first portion 2510a during use of the device 2599, the first
portion 2510b is configured such that third opening 2503 is not in
fluidic communication with the channel 2504, first opening 2501 and
second opening 2502. In other words, a volume 2508 defined by
sidewall 2506 that extend distally from the third opening 2503 does
not extend so far as to extend to any portion of channel 2504.
However, to ensure that the second portion 2510b can be securely
attached onto the first portion 2510b (although the two portions
may still be released from one another), the volume 2508 should
extend distally from opening 2503 at a length equal to or greater
than a length of the distal tip 2510a' of the first portion, which
can be threaded to couple with matching threads on sidewall
2506.
[0185] In one exemplary method of using the device 2599, a medical
procedure as cerebral spinal fluid collection is performed by a
user/clinician on a patient. Prior to powering the device, the user
attaches the second portion 2510b (with sharps member already
attached thereto) to the first portion 2510a. If a sharps member is
not already attached to the second portion 2510b, the user also
attaches a sharps member at the distal first opening 2501 of second
portion 2510b. While for this example, the sharps member would
preferably be a spinal access needle, in other procedures the
sharps member can be, for example, an epidural needle such as a
Tuohy needle, catheterization needle, venous access needle, bone
biopsy needle, or other sharp object for use in penetrating tissue
and other bodily materials.
[0186] The user provides power to the device by energizing it. Upon
energizing the device, for example, by turning a power switch to an
"on" position, a controller's microprocessor having been
preprogrammed, initiates a power-on algorithm that includes
delivering a voltage to the piezoelectric stack 2514. The delivery
of a voltage causes the piezoelectric stack to expand which causes
other portions of the actuator to expand, such as at a distal tip
of the second portion 2510b.
[0187] Voltage can be provided to the actuator at various
predetermined signaling patterns, such as a continuous sinusoidal
pattern at a particular frequency or varying frequencies. In some
embodiments, the voltage can be delivered to the actuator in a
pulsed mode in which the voltage is delivered in groups of
continuous sinusoidal patterns, each group consisting of at least
one frequency and each group being delivered at least one a
predetermined frequency.
[0188] Upon powering up, the microprocessor can initiate an
algorithm for determining a reference resonant frequency, for
example, before the device penetrates tissue. To determine the
reference resonant frequency, the microprocessor can perform a
frequency sweep as shown in FIG. 32a, from which the impedance
magnitude (voltage amplitude to current amplitude ratio) and phase
(i.e., phase angle of impedance is simply the relative phase
between the voltage and current signals) can be determined. For
example, a frequency sweep can begin at a frequency (F.sub.t1) in
which a voltage is applied and a corresponding current is measured
by, for example, an impedance analyzer connected to the controller.
The frequency can be subsequently increased by a certain increment,
with each of impedance magnitude and phase being measured at
additional frequencies, such as at frequencies Ft2, Ft3 as shown in
FIG. 32a, through to a maximum frequency in a predetermined range
of frequencies. The impedance analyzer can identify the impedance
at a given frequency, and a microprocessor connected to the
impedance analyzer can store the measured values relative to the
output current and output frequency. As shown in FIG. 32b, the
resonant frequency (F0) of the device is selected as the frequency
at which the corresponding impedance measured at each frequency in
the sweep range is a minimum. In addition to, or alternatively, the
resonant frequency can be selected as the frequency corresponding
to a predetermined phase angle (e.g. 0) that corresponds to the
typical minimum impedance of the device 2599. The frequency
corresponding to the minimum impedance magnitude occurs (or
corresponding to the measured phase angle that matches a
predetermined target phase angle) is determined to be a standard
reference frequency at which the device will be initially driven to
ensure maximum displacement. Accordingly, the controller provides
power to the device at the reference frequency.
[0189] As the sharps member is brought into contact with and
penetrates tissue, the impedance spectrum of the device will
change. FIG. 32c illustrates a hypothetic shift in the impedance
spectrum of the device as it encounters resistance, such as tissue.
FIG. 32c shows that if the device is continued to be driven at the
initial reference resonance frequency, the impedance magnitude
would increase while the impedance phase would decrease or more
negative. Conversely, as shown in FIG. 32d, if the characteristic
impedance spectrum were to shift in the opposite direction, both
the impedance magnitude and phase would increase in the positive
direction, provided the shift were not too great.
[0190] In order to adjust the driving frequency to match the new
resonant frequency (identified as F1 FIG. 32d), the controller can
increase the driving frequency until the impedance analyzer
measures that the phase has returned to the target phase (eg. 0)
and/or until the impedance minima is again detected during a
secondary sweep of the frequency through a specified range that at
least overlaps with the initial range, is the same as the initial
range, or a smaller subset of frequencies within the initial
range.
[0191] Thus, as shown in FIG. 27, a method for penetrating a living
being is described. As discussed above, a medical device such as
device 2599 is powered and a controller in communication therewith
performs an initial frequency sweep. Initially, the device is
powered/energized at step 2702 to actuate/vibrate the device's
sharps member 2520 at a reference resonance frequency that provides
for a reduction of force initially required to penetrate through a
medium. The resonance frequency can, for example, be selected from
the range of 20-21 kHz or 30-32 kHz. However, the resonance of the
device can shift with changes in temperature and mechanical
loading. For example, this shift can be up to about 3 kHz, which if
the operating frequency is not adjusted, it will operate in a
non-efficient operating mode. Accordingly, as the device is moved
toward the epidural space, as in step 2704, by the clinician, or an
external source of motion, the sharps member 2520 is eventually
brought into contact with the patient's tissue. As described above,
the driving resonance frequency will be adjusted so as to maintain
resonance.
[0192] Accordingly, as the device initially penetrates into a
living being, such as insertion in a direction toward, for example,
the epidural space as shown in step 2704, and the resonance value
shifts a feedback subsystem performs a monitoring algorithm that
measures electromechanical properties and adjusts the resonance
frequency according to a predetermined algorithm. In other words,
the device monitors vibrational response as the needle penetrates
through tissue.
[0193] The vibrational response can be monitored, for example via a
feedback system that automatically tracks electromechanical
properties of the device, such as impedance, as shown in step 2706.
This can be done, for example, by programming the microprocessor of
FIG. 28 to perform a series of impedance or resonance frequency
measurement sweeps (e.g., impedance value v. frequency; resonance
frequency v. time; phase angle vs. frequency; phase angle shift vs.
time), storing and/or displaying corresponding measured values,
and/or comparing those measured values to known values, and/or
comparing the measured values to a known relationship between
values. In an embodiment, the processor can be programmed to
identify characteristics of values related to electromechanical
properties of the device as it vibrates through
tissues/materials/fluids/gases of a being (e.g., living being).
[0194] For example, the task of tracking a resonance frequency can
be accomplished by first causing the controller to electronically
perform a sweep across a range of frequencies. The range of
frequencies can be set by the operator, or can be preset. For
example, the controller can be programmed or set by the user to
perform a sweep across a range of frequencies such as 19.5 kHz to
21.5 kHz. The frequency at which the device produced the maximum
response (i.e., largest displacement of the sharps member's distal
end which will typically occur at a minimum measured/calculated
impedance magnitude), the controller can be set to operate the
device's actuators at the corresponding resonance frequency. While
a tracking cycle, such as that described above, is necessary to
maintain efficiency (i.e., so that the driving signal from the
controller to the actuator can change as fast as the resonance
shift changes), it would take too long for the device's electronics
to constantly perform frequency sweeps. Thus, in addition to or
alternatively, a continuous tracking method can be employed as
described below. For example, the feedback subsystem can be
programmed to monitor the magnitude and phase of the voltage and
current signals, which can then be used to calculate a resonance
frequency. Upon calculating an updated resonance frequency for each
cycle of monitoring the magnitude and phase of the voltage and
current signals using the continuous tracking method, or at given
time intervals (such as running a new calculation and adjusting the
driving frequency at a rate of 5-10 Hz; i.e., the resonance
frequency can be updated 5 to 10 times every second), the
controller can use the updated frequency to compensate for a shift
in resonance.
[0195] In an embodiment, the measurements can provide values that
are the result of physical interactions of the sharps member with
materials (e.g., as a hollow sharps member is filled with and/or
surrounded by tissues/materials/fluids/gases). The processor can
determine the resulting device impedance or resonance frequency
signal curves as discussed above and can determine the location of
corresponding maximums and minimums, and/or can calculate slopes.
These calculations can be further utilized to determine
characteristics of the tissue, the location of the needle within a
being, or to automatically adjust the power required for the needle
to maintain a particular driving pattern, for example, a resonance
frequency. As the user continues to move the powered device toward
a desired location within a living being, the microprocessor can
monitor transient changes in impedance to maintain resonance and/or
store the measured electromechanical properties as patterns or
graphical representations, and compare the pattern of
monitored/measured electromechanical properties to a pattern
corresponding to a known condition which can be stored in a
database accessible by the processor in the feedback system, as
shown in step 2708.
[0196] In other words, via impedance sweeps (wherein signals are
generated by the device's electronics and stored in a connected
memory, and/or generated and displayed to the user on a connected
display, wherein the signals are translated into corresponding
numerical values representative of impedance and/or frequency; or
another value that identifies the tissue being penetrated through)
performed by the device's electronics, the device's connected
controller (such as a microprocessor) can be programmed to
automatically track the real-time impedance magnitude at a given
resonant frequency (or particular driving frequency) of the device
as the needle advances toward, or is brought adjacent to, within,
and through the ligamentum flavum. Via monitoring of selected
electromechanical properties as a function of, for example, time,
the device's microprocessor can also build a catalog of stored
patterns corresponding to changes in the electromechanical
properties and can compare these changes to stored changes
representative of a known condition. In one example, the
microprocessor has measured and stored values in a memory, the
values corresponding to resonance frequency, impedance magnitude,
phase angle and/or penetration force (such as provided by a force
sensor in contact with the device and the feedback system). The
electromechanical properties can be measured simultaneously, for
example using LabBiew software (National Instruments, Austin,
Tex.), a shimpo 20 lb capacity force gauge model FGV (Itasca, Ill.)
and an HP4194A Impedance analyzer. The microprocessor can then
retrieve the stored/measured values and compare how the values have
changed relative to other values corresponding to a similar
electromechanical property or to other electromechanical
properties. The microprocessor can then compare the measured/stored
values to a known pattern of values, such as the pattern shown in
FIG. 29 indicative of a known condition, such as penetration
through the ligamentum flavum and advancement of the sharps member
into the epidural space. The microprocessor can then either
determine that the measured values are similar to or different from
the referenced pattern of values in the database, based on whether
the comparison falls within a mathematically predetermined error
value.
[0197] Additionally, during all steps when the device is powered,
feedback subsystem continuously attempts to maintain the driving
frequency at a resonant frequency as discussed above.
[0198] Thus, when one of the above mentioned sweeps is performed
and signals are collected and stored in a machine readable medium,
such as a computer memory, as the needle tip penetrates the
ligemantum flavum, the device electronics can be configured to be
manipulated by software stored in a computer to automatically
powerdown the device upon generating and storing a value that
compares statistically equivalent to a known value indicative of
entry of the needle into the epidural space. Such a method of
operation that relies on the electromechanical properties of the
device is generally described in related U.S. Provisional
Application No. 61/441,500 filed on Feb. 10, 2011 and, 61/441,677
filed on Feb. 11, 2011, both of which are incorporated by reference
herein in their entireties.
[0199] Continuing in FIG. 27, upon the needle reaching the epidural
space as it is advanced by the user, the device's actuators can be
powered down (and/or some or all of the actuation of the needle can
be terminated) as discussed above and shown in step 2710. The
device, via its feedback subsystem and associated power controller,
can then automatically perform a fresh baseline impedance sweep
(e.g., impedance phase angle vs. Frequency) as described in step
2710. Alternatively, the clinician can manually cause the device's
electronics to execute a baseline impedance sweep (e.g., clinician
can depress an electronic switch programmed to initiate a baseline
sweep). Upon generation and detection of electronic signals during
the sweep(s), values of the electronic signals are assigned to
corresponding impedance values (e.g., impedance phase angle) and
the measured baseline impedance spectrum is stored in the device's
memory.
[0200] FIG. 31 shows how impedance and phase measurements can
exhibit a specific peak in the phase response. Such a peak can
correspond to a known even, such as the presence of fluid in the a
device's sharps member. Data in FIG. 31 was taken using a 25G
atraumatic spinal needle with saline as the working fluid. A shift
in phase of 100-400 Hz occurs when 2.5 cm of the needle (from the
distal end) is filled with saline.
[0201] Continuing with the method in FIG. 27, as the clinician now
advances the devices toward the subarachnoid space, as shown in
step 2712. The baseline impedance sweep can be understood as the
collection of data that corresponds to a baseline curve such as the
"Dry Needle" curve shown in FIG. 31. The device then automatically
performs additional sweeps, storing the additional changes in
electromechanical properties, such as impedance phase angle, and
compares those to a reference database that includes a pattern of
impedance phase angles representative of a change in a physical
condition of the device, such as when the sharps member penetrates
the subarachnoid space and fills with cerebral spinal fluid. Such a
known condition can be represented by the impedance phase angles
shown in graph in FIG. 31 for a saline filled needle. In other
words, as the device is advanced further into the living being, for
example, in a direction from the epidural space toward the
subarachnoid space, several sweeps can be performed to measure an
impedance spectrum corresponding to the location of the device's
needle as shown in step 2714. For each sweep, the measured
impedance spectrum is compared to the baseline or original stored
spectrum (or to a known value previously stored in memory) as shown
in Step 2716. Steps 2712 and 2714 can be understood as the
collection of data that corresponds to a measurement curve, such as
the "Saline-filled Needle" curve shown in FIG. 31, which can occur
when the needle in use is filled with cerebral spinal fluid (CSF)
for comparison with the baseline.
[0202] In step 2718, the feedback system is utilized to measure
whether there exists a difference between the measured impedance
spectrum and the original/stored/baseline spectrum. If the
difference is determined to be greater than a predetermined
threshold value (such as A1, F1, A2 or F2 as shown in FIG. 31), the
device can be configured to provide tactile, audible or visual
indication (such as via a display as in step 2722) to the operator
indicating its location (such as having encountered cerebral spinal
fluid in the subarachnoid space) and/or programmed to automatically
power down the actuation. In other words, once the needle has
reached the epidural space, the device begins to monitor the
impedance spectrum over a narrow frequency range (at low voltage,
non-powered) to form a baseline. Each subsequent sweep of the
spectrum will be compared against the initial baseline (e.g., the
first sweep after entering epidural space). Once there has been a
significant change in select features (e.g. a shift in impedance
phase peaks) in the spectrum, corresponding to the change in
electromechanical properties of the device as the needle fills with
CSF, sensory indicator s(audio/visual/tactile) inform the clinician
that needle has come into contact (i.e., filled partially or
surrounded by) with CSF and has entered the subarachnoid space.
[0203] FIGS. 29-31 are graphical representations of data that can
be gathered by a processor that receives signals from a sensor. The
processor converts the received signal into a corresponding value
representative of a particular electromechanical property. Through
the use of software that controls the computing function of the
processor, the processor can be programmed to recognize
correlations within a single electromechanical property (such as a
change in the property), or correlations between several
electromechanical properties. For example, within the dashed box in
FIG. 29, a vertical line represents a particular characteristic
between various electromechanical properties and other measurable
physical properties, such as an abrupt shift in resonance
frequency, phase angle, impedance magnitude and/or penetration
force that could be correlated to a predetermined value, or a set
of values indicative of a known event. The dashed box in FIG. 30
shows an abrupt change in force, as measured by a force sensor
(such as a low-voltage piezoelectric ring sensor). The abrupt
change could be correlated to a known or predetermined change
representative of, for example, successful penetration of the
sharps member into the epidural space. The predetermined value,
change, or known value can either included in a controlling
software or stored in a database, such as an updatable database
connected to the internet and to a central server to which updates
can be sent by one user to be downloaded by another user. The
subsystem can reference this value for updating particular
parameters of the device 200 operation.
[0204] Referring to FIG. 33, a flow diagram illustrating steps of a
method is illustrated. The method 3300 can be implemented as
actions performed by a microprocessor, such as the microprocessor
in FIG. 28 of a feedback subsystem, such as feedback subsystem 2400
of FIG. 24, for controlling the operation of a device, such as
device 2599 of FIG. 25. The process begins with powering up (step
3302) of a control unit, in which the microprocessor is housed. The
control unit provides power and electronically controls the
functioning of an attached actuator of the device which can be
energized to provide reciprocating motion to sharps/penetrating
member for reducing the force required to penetrate into tissue,
such as to perform a medical procedure. In step 3304 the actuator
is interrogated in order to determine baseline properties that will
be used to set the optimal driving parameters and verify the proper
actuator is attached for the desired procedure. An interrogation
can include verification that the actuator is functioning properly.
An interrogation can include a sweep across a range frequencies,
such as ultrasonic frequencies, in which a voltage signal is
delivered to the actuator. It is possible that the controller can
be designed to control a number of different actuators and/or
perform a number of different medical procedures with various
actuators.
[0205] For each medical procedure, there may be a specific set of
driving parameters or instructions such as control of power level
and/or voltage for a particular operation mode, what the duty cycle
and/or pulse rate should be, what impedance phase to target in
trying to maintain resonance, etc. For example, the procedural
requirements for driving the actuator may be different for
puncturing a vein than puncturing through the dura mater to the
subarachnoid space as with placing a spinal needle for a
cerebrospinal fluid (CSF) sampling procedure. The values for any
driving parameter may be specific, or perhaps be bounded by upper
and lower limits to ensure safe device function. Furthermore, some
procedures may involve several intermediate steps, each of which
may require different driving parameter settings.
Procedure-specific device settings, including the possibility of a
list of different device settings for individual procedural steps
of a complete medical procedure, may be previously stored in a
database and retrieved in step 3306. Based partially on the device
interrogation of step 3304, as well as the needs of the specific
medical procedure, the processor can selected optimum driving
parameters in step 3308. Upon selecting optimum driving parameters,
the processor can activate the actuator automatically (step 3310)
or upon receiving manual input from the user. The term "activate"
can include powering the actuator to achieve vibrational
displacement capable of reducing penetration force (achieving an
ROF effect), as well as lower power activation which employs the
actuator as an active interrogator of the mechanical property
changes that take place at the sharps/penetrating member-tissue
interface. For instance, the electrical impedance spectrum of a
piezo-electric device obtained by sending low-voltage sinusoidal
signaling of varying frequencies to the active elements, such as
piezoelectric actuator elements will change as the penetrating
member is pushed into different media. For example, FIG. 23, shows
examples of impedance spectrum upon penetrating through different
media.
[0206] With device in activated state, the "Procedural Step Loop"
is entered at step 3312. Within the "procedural step loop", the
sharps/penetrating member that is attached to the actuator is
steadily advanced through the living being tissue (step 3312), the
actuator and/or integrated sensors (e.g. for measuring force,
impedance magnitude, phase angle) are periodically monitored (step
3314) to measure and calculate changes in electromechanical
properties, for example as the device and device components are
influenced by tissue/fluids in and around the sharps/penetrating
member (i.e., external forces acting on the device). In step 3318,
the current electromechanical property values or time-varying
trends in some or all of the electromechanical variables relating
to the state of the actuator or the tissue/fluids in and around the
sharps/penetrating member may be compared to a database of
pre-defined property states or anticipated trends in those
characteristics. If the pattern of current electromechanical
properties or trends matches a pre-defined pattern or trend, for
example within a statistical error, the current procedural step is
complete (step 3320). If not, the driving parameters may be
re-adjusted to maintain optimal performance and another iteration
of the Procedural Step Loop commences. A user display may be
updated (step 3322) each time through the loop to keep the user
updated about progress through the current procedural step as well
as indicate when the current step is completed. The user display
may include haptic, audible, or visual feedback.
[0207] If the procedural step 3320 is completed, it must be
determined whether the overall procedure, such as the medical
procedure, is complete (step 3326). In other words, the subsystem
must determine whether all intermediate procedural steps are
complete or not. If so, the user can be notified (step 3322), and
the system can enter a power down or standby state indefinitely
(step 3330). The power down state may also be entered at any point
in a procedure manually by the user, or when the monitored
electromechanical properties indicate that a malfunction or unsafe
state has been entered. Otherwise, if additional steps in the
procedure are required to be performed, the controller transitions
to the next procedural step (as described in step 3328). Before
entering the Procedural Step Loop again, the driving parameters may
be changed to accomplish the needs of the next procedural step
according to the device settings database entry for that specific
procedural step. The process continues until the desired medical
procedure is completed.
[0208] A example demonstrating how the process would be implemented
for a specific medical procedure is now described for that of a
diagnostic cerebrospinal fluid (CSF) sampling procedure with
respect to the method steps described above. A piezoelectric
actuator is outfitted with a spinal needle incorporated into the
distal horn. The system is powered up (3302) and the control unit
performs a frequency sweep to obtain the impedance spectrum and
identify the reference resonant frequency (3304), such as according
to methods described in FIG. 32 and above. The processor can
communicate with a database (as described in step 3306) to receive
parameters for programming the device (3308) to operate with a set
of initial driving parameters (e.g. voltage level, impedance phase
angle to maintain in order to keep device operating at resonance,
duty cycle, etc.) to accomplish the first procedural step:
inserting the spinal needle through the ligamentum flavum with ROF
effect. The device is activated (3310) and the clinician advances
the spinal needle through tissues while monitoring the
electromechanical properties (force sensor reading, abrupt
impedance phase angle change, or impedance magnitude change;
similar to that observed in FIG. 29) for evidence of pop-through as
needle enters epidural space (Procedural Step Loop iterations).
Meanwhile the operating frequency is regularly adjusted/updated
(3324) to maintain optimal ROF effect (i.e. maintain actuator at
resonance). Once evidence of ligamentum flavum pop-through is
detected (3318, 3320), the next procedural step (detect CSF filling
within needle) is initiated. For this step, the ROF effect may be
less important so the driving voltage may be lowered (at step 3308,
after querying the procedure-specific settings database) so
displacements are less. This may be desired to minimize the chance
for nerve damage. Even in a low-powered state, impedance spectrum
changes may indicate CSF filling. Once CSF flow is detected, based
primarily on specific changes in the impedance spectrum or by
pattern match (implemented in steps 3316, 3318, and 3320), the
procedure would be complete, and this would be indicated to the
user (3322) and the actuator/system could be powered off (3330)
while the clinician carries out the remaining steps to obtain and
secure the CSF fluid sample for laboratory analysis.
[0209] Now that exemplary embodiments of the present invention have
been shown and described in detail, various modifications and
improvements thereon will become readily apparent to those skilled
in the art. While the foregoing embodiments may have dealt with the
penetration through skin, bone, veins and ligaments as exemplary
biological tissues, the present invention can undoubtedly ensure
similar effects with other tissues which are commonly penetrated
within the body. For example there are multiplicities of other
tools like central venous catheter introducers, laparoscopic
instruments with associated sharps, cavity drainage catheter kits,
and neonatal lancets, as well as procedures like insulin
administration and percutaneous glucose testing, to name a few,
where embodiments disclosed herein comprising sonically or
ultrasonically driven sharps members may be used to precisely
pierce or puncture tissues with minimal tinting. Accordingly, the
spirit and scope of the present invention is to be construed
broadly and limited only by the appended claims, and not by the
foregoing specification.
REFERENCE LABELS
[0210] .alpha. Bend angle [0211] A Static needle force curve [0212]
B Vibrating needle force curve [0213] G1 Displacement Graph [0214]
LT Langevin actuator (also known as Langevin transducer) [0215] PA1
Conventional biopsy needle [0216] PA2 Conventional epidural needle
[0217] PA3 Conventional Syringe [0218] PT Pressure transducer
[0219] S Switch [0220] SP Side Port [0221] ZN Zero node [0222] 1
Cannula [0223] 1' Cannula distal end [0224] 2 Stylet [0225] 3
Distal tip [0226] 4 Stylet tip angled face [0227] 5 Tuohy needle
[0228] 6 Tuohy curved tip [0229] 7 Tip opening [0230] 9 Front
portion [0231] 10 Tubular body [0232] 11 Biasing element [0233] 12
Plunger [0234] 14 Inner Stylet [0235] 15 Outer trocar tube [0236]
16 APA needle [0237] 16b Alternate embodiment [0238] 20 Penetrating
member [0239] 100 Langevin actuator [0240] 110 Horn [0241] 111
Support wings [0242] 112 Rear mass [0243] 114 Piezoelectric
elements [0244] 114b Electrical conductors [0245] 115 Sterilization
sleeve [0246] 116 Bolt [0247] 117 Battery & inverter
compartment [0248] 118 Handle [0249] 120 Seal [0250] 121 Distal
face [0251] 122 Distal opening [0252] 123 Luer taper nose [0253]
124 Proximal opening [0254] 126 Bore [0255] 126a Short bore [0256]
128 Attachment fitting [0257] 129 Catheter [0258] 130 Hollow needle
[0259] 130a Distal end of hollow needle [0260] 130b Proximal end of
hollow needle [0261] 132 Plunger handle [0262] 134 Plunger shaft
[0263] 134a Proximal end of plunger shaft [0264] 134b Distal end of
plunger shaft [0265] 136 Plunger seal [0266] 142 Inner stylet
handle [0267] 144 Inner stylet shaft [0268] 146 Inner stylet tip
[0269] 148 Trocar attachment fitting [0270] 150 Outer trocar body
[0271] 152 Distal trocar opening [0272] 154 Distal trocar tip
[0273] 200 Penetrating introducer [0274] 202b More preferred
embodiment [0275] 202c Most preferred embodiment [0276] 201
Supported introducer [0277] 202 Catheterization introducer [0278]
300 Bone biopsy device [0279] 400 Advanced bone biopsy device
[0280] 500 APA syringe [0281] 500b Alternate embodiment [0282] 510
Amplified piezoelectric actuator (APA) [0283] 512 Frame [0284] 512a
Proximal end of frame [0285] 512b Distal end of frame [0286] 513
Penetrating member [0287] 513a Proximal end of penetrating member
[0288] 513b Distal tip of penetrating member [0289] 514
Piezoelectric material [0290] 516 APA attachment point [0291] 518
Handle [0292] 521 Handle distal opening [0293] 524 Handle proximal
opening [0294] 525 Penetrating member hub [0295] 526 APA bore
[0296] 600 Cymbal syringe [0297] 600b Alternate embodiment [0298]
610 Cymbal actuator [0299] 612 Endcap [0300] 612a Proximal endcap
[0301] 612b Distal endcap [0302] 626 Cymbal bore [0303] 616 Cymbal
attachment point [0304] 700 General side port configuration [0305]
700a First side port configuration [0306] 700b Second side port
configuration [0307] 701 Feedback subsystem [0308] 702
Microcontroller [0309] 704 Drive Electronics [0310] 800 Feedback
capable reduction of force tool [0311] 900 Medical tool using voice
coil actuator [0312] 900b Alternate voice coil embodiment [0313]
902 Conducting coil [0314] 904 Magnetic member [0315] 906 Coil
support tube [0316] 910 Body [0317] 912 Driving tube [0318] 914
Extension member [0319] 916a First attachment point [0320] 916b
Second attachment point [0321] 918 First conductive attachment site
[0322] 920 Second conductive attachment site [0323] 922 Second
conductive coil [0324] 1000 Medical tool using solenoid actuator
[0325] 1002 Solenoid coil [0326] 1004 Magnets [0327] 1014 Spring
[0328] 1020 Pressure feedback system [0329] 1021 Reservoir with
integrated pump [0330] 1022 Flexible tubing [0331] 1023 Attachment
fitting [0332] 1024 Base [0333] 1025 On/off switch [0334] 1026
Light emitting diode [0335] 2100 Electrical Cutoff Configuration
[0336] 2400 Feedback subsystem [0337] 2402 Microcontroller [0338]
2404 Drive electronics [0339] 2500 Actuator [0340] 2501 first
opening [0341] 2502 second opening [0342] 2503 third opening [0343]
2504 channel [0344] 2506 sidewall [0345] 2507 flat surface [0346]
2508 volume [0347] 2510 Displaceable Member [0348] 2510a First
Portion [0349] 2510a' Distal Tip [0350] 2510b Second Portion [0351]
2520 Sharps Member [0352] 2512 Rear Mass [0353] 2514 Piezostack
[0354] 2515 Distal end [0355] 2514a piezoelectric element [0356]
2514b piezoelectric element [0357] 2518 Handpiece [0358] 2522 Force
Sensor [0359] 2524 distal interface [0360] 2525 proximal interface
[0361] 2526 gap [0362] 2599 Device
* * * * *