U.S. patent application number 14/003745 was filed with the patent office on 2013-12-19 for fluid vessel communication device.
This patent application is currently assigned to OLBERON MEDICAL INNOVATION SAS. The applicant listed for this patent is Amin H.A. Al-Habaibeh, Arash Bakhtyari-Nejad-Esfahani, Thomas David Stead. Invention is credited to Amin H.A. Al-Habaibeh, Arash Bakhtyari-Nejad-Esfahani, Thomas David Stead.
Application Number | 20130338577 14/003745 |
Document ID | / |
Family ID | 43923454 |
Filed Date | 2013-12-19 |
United States Patent
Application |
20130338577 |
Kind Code |
A1 |
Al-Habaibeh; Amin H.A. ; et
al. |
December 19, 2013 |
Fluid Vessel Communication Device
Abstract
A fluid vessel insertion device (10), typically for medical use,
comprises a puncture member (18) arranged for location within a
sleeve (20), and a retraction mechanism (44, 48, 60) for retracting
the puncture member relative to the sleeve. The puncture member
(18) is retractable in use between a first condition in which an
end (18A) of the puncture member protrudes beyond an end (24) of
the sleeve and a second condition in which the end of the puncture
member is within the sleeve (20). The retraction mechanism (44, 48,
60) actuates the puncture member between the first and second
conditions in response to fluid pressure at the end (18A) of the
puncture member. The device may be used during positioning of the
sleeve in a desired fluid vessel, such as, for example, during
intravenous cannulation.
Inventors: |
Al-Habaibeh; Amin H.A.;
(Nottingham, GB) ; Bakhtyari-Nejad-Esfahani; Arash;
(Nottingham, GB) ; Stead; Thomas David;
(Nottingham, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Al-Habaibeh; Amin H.A.
Bakhtyari-Nejad-Esfahani; Arash
Stead; Thomas David |
Nottingham
Nottingham
Nottingham |
|
GB
GB
GB |
|
|
Assignee: |
OLBERON MEDICAL INNOVATION
SAS
Loos
FR
|
Family ID: |
43923454 |
Appl. No.: |
14/003745 |
Filed: |
March 9, 2012 |
PCT Filed: |
March 9, 2012 |
PCT NO: |
PCT/GB12/50530 |
371 Date: |
September 6, 2013 |
Current U.S.
Class: |
604/67 ; 604/117;
604/164.08 |
Current CPC
Class: |
A61M 25/0693 20130101;
A61B 17/3496 20130101; A61M 25/0612 20130101; A61B 17/3415
20130101; A61M 5/158 20130101 |
Class at
Publication: |
604/67 ;
604/164.08; 604/117 |
International
Class: |
A61B 17/34 20060101
A61B017/34 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 9, 2011 |
GB |
1104016.9 |
Claims
1. A fluid vessel insertion device comprising: a puncture member
arranged for location within a sleeve, and a retraction mechanism
for actuating the puncture member relative to the sleeve in use
between a first condition in which an end of the puncture member
protrudes beyond an end of the sleeve, and a second condition in
which the end of the puncture member is retracted within the
sleeve, wherein the retraction mechanism actuates the puncture
member between the first and second conditions in response to an
external fluid pressure at the end of the puncture member.
2. A device according to claim 1, wherein the puncture member is
hollow to allow fluid communication with the retraction
mechanism.
3. A device according to claim 1, wherein the device comprises a
medical device and the puncture member comprises a needle.
4. A device according to claim 1, wherein the retraction mechanism
comprises a chamber.
5. A device according to claim 4, wherein the chamber is maintained
at substantially ambient pressure in an at-rest state and is
arranged to trigger the retraction mechanism to actuate the
puncture member into the second condition when a pressure gradient
is experienced between the interior of the chamber and the external
pressure at the end of the puncture member.
6. A device according to claim 5, wherein the puncture member
extends into the chamber and comprises an aperture for fluid
communication with the interior of the chamber and the interior of
the chamber is substantially sealed from the exterior of the device
save for via the puncture member aperture.
7. (canceled)
8. A device according to claim 1, wherein the retraction mechanism
triggers retraction of the puncture member automatically upon
sensing a pressure at or beyond a predetermined pressure difference
from ambient at the end of the puncture member.
9. A device according to claim 8, wherein the retraction mechanism
comprises a pressure sensor.
10. A device according to claim 8, wherein the retraction mechanism
comprises a chamber and a diaphragm which is actuable in response
to a change in pressure within the chamber.
11. A device according to claim 1, wherein the retraction mechanism
comprises a chamber in fluid communication with the end of the
puncture member and an engagement member arranged to releasably
engage the puncture member dependent on the pressure within the
chamber.
12. A device according to claim 11, wherein the puncture member is
biased towards the second condition and is releasably held in the
first condition by the engagement member.
13. A device according to claim 12, wherein the puncture member is
biased by a spring.
14. A device according to claim 1 comprising a stop member arranged
to limit travel of the puncture member by the retraction mechanism
to a predetermined distance.
15. A device according to claim 1, comprising a housing for the
retraction mechanism, wherein the puncture member depends from the
housing such that a first end of the puncture member is spaced from
the housing and a second end of the puncture member is mounted in
the housing.
16. (canceled)
17. A device according to claim 8, wherein the retraction mechanism
comprises a chamber and an electronic pressure sensor within the
chamber, the device further comprising a controller arranged to
trigger retraction of the puncture member between the first and
second conditions.
18. A device according to claim 17, wherein the retraction
mechanism comprises an electric actuator.
19. A fluid vessel communication assembly comprising the device of
claim 1 and a sleeve arranged to closely surround the puncture
member in the vicinity of the end thereof.
20. An assembly according to claim 19, wherein the sleeve has an
open end through which the puncture member protrudes in the first
condition, the open end of the sleeve being immediately adjacent
the end of the puncture member in the first condition.
21. An assembly according to claim 19, wherein the sleeve is
detachably mounted to a housing for the retraction device at a
location spaced from the end of the puncture member such that the
puncture member retracts relative to both the housing and sleeve
during actuation between the first and second conditions.
22. An assembly according to claims 19, wherein the sleeve
comprises a cannula.
Description
[0001] The present invention relates to a fluid vessel
communication device and more particularly to a device for
insertion into a vessel so as to allow fluid communication with the
interior of the vessel. Such devices may be used in medical
applications although they are not limited thereto.
[0002] In order to communicate with an existing fluid vessel it is
often required to puncture a vessel wall so as to provide a port
therein. In the event that ongoing fluid communication is required
with the vessel, it may be required to establish a vessel junction
such that the puncturing member has to be removed and replaced with
a more suitable fluid conduit, which, for example, carries a
reduced risk of causing further unwanted damage to the vessel.
[0003] Within the medical field, there are a number of scenarios in
which it is necessary to puncture fluid vessels in the manner
described above for delivery of fluid to, or removal of fluid from,
a fluid vessel in the body.
[0004] Intravenous cannulation is a common example of such a
medical procedure. It is estimated that there are at least 25
million cannulations a year in the UK alone. Intravenous
cannulation is expected routinely to fail in 20-30% of initial
attempts and can prove to be problematic for certain patient groups
or inexperienced operators.
[0005] The inventors have determined that at least a portion of
failed cannulation attempts can be attributed to the fact that the
walls of fluid vessels in the body, such as blood vessels, often do
not offer a significant increase in resistance to the travel of a
needle compared to the surrounding tissue. Also the depth of the
vessel to be punctured may be relatively small such that the
operator has little scope for error when attempting to position the
needle end with in the vessel. The combination of a small target
zone and low tactile feedback mean that operators frequently do not
realise when a needle is correctly located in a vein and may insert
a needle through the vein and thereby fail in the correct
positioning of both the needle and cannula.
[0006] Even if an operator does correctly interpret the point at
which the vessel is punctured, there remains the possibility that
any unintentional movement of the operator or a patient thereafter
could cause further puncturing of the vessel, for example through
the opposing vessel wall, resulting in a failed cannulation
attempt.
[0007] Effort has been expended in the past to provide devices
which present additional feedback to an operator to aid in
determining the location of a needle within the body. U.S. Pat. No.
7,175,608 provides an example of such a device, which is specific
to the detection of the negative pressure within the epidural
space, and which aims to provide a visual indication of correct
needle positioning to an operator.
[0008] However the provision of a visual indication of correct
needle positioning to an operator in order to supplement the
relatively low level of tactile feedback only provides a partial
solution to the problems discussed above. Furthermore a visual
indication can draw an operator's focus away from the precise point
of insertion and the advancement of the needle therein.
[0009] It is an aim of the present invention to provide a fluid
vessel insertion device which allows for improved accuracy and/or
reliability of insertion.
[0010] According to the present invention there is provided a fluid
vessel insertion device comprising a puncture member arranged for
location within a sleeve, and a retraction mechanism for retracting
the puncture member relative to the sleeve in use between a first
condition in which an end of the puncture member protrudes beyond
an end of the sleeve and a second condition in which the end of the
puncture member is within the sleeve, wherein the retraction
mechanism actuates the puncture member between the first and second
conditions in response to fluid pressure at the end of the puncture
member.
[0011] Fluid pressure may be considered to comprise any or any
combination of static or dynamic fluid pressure and may be separate
from the contact or friction force experienced by the puncture
member due to passage through a vessel wall or surrounding
material.
[0012] The determination of fluid pressure as the trigger for
retraction of the puncture member is advantageous since it allows
accurate assessment of the point of entry of the puncture member
into a vessel of generally known or predictable internal fluid
pressure. The determination may be made based on a deviation of
fluid pressure form an ambient fluid pressure level. The
determination is advantageously not reliant on feedback pertaining
to the resistance of the vessel wall to puncturing.
[0013] Furthermore the retraction of the puncture member relative
to the sleeve requires minimal movement and/or retraction force.
Thus the sleeve can reliably remain in the desired position within
a vessel with minimal disturbance.
[0014] The retraction mechanism may be actuated in response to a
positive fluid pressure at the end of the puncture member, for
example due to a fluid pressure at the end which is greater than
atmospheric pressure and/or greater than a fluid pressure level
within the device, or a part thereof, such as an internal chamber,
which may be within the device.
[0015] The sleeve may be mounted in a fixed position/orientation
with respect to any, or any combination, of the device, the
retraction mechanism, the chamber and/or the device housing. The
sleeve may be mounted to a support formation, which is in turn
removably attachable to the device to provide the desired
orientation in use but which is detachable there-from once the
puncture member has been retracted.
[0016] The puncture member may be shaped to allow fluid
communication with the retraction mechanism. Typically the puncture
member is hollow and allows for the passage of fluid therein. The
puncture member may be elongate and/or tubular in form. The
puncture member may be tapered towards a sharp end and may comprise
a needle or trocar.
[0017] A hollow puncture member allows fluid pressure at the end of
the puncture member to be determined at a spaced location. The
retraction mechanism may comprise a chamber in communication with
the interior of the puncture member. Accordingly the fluid pressure
at the end of the puncture member may be experienced by the
chamber.
[0018] The chamber may be located within a body or housing of the
device. The chamber may be maintained at a first, typically
atmospheric, pressure in an at-rest condition, which may correspond
to the first condition of the retraction mechanism. The chamber may
have an actuated condition, which may correspond to the second
condition of the retraction mechanism. The change from the first to
the second condition of the chamber and/or retraction mechanism may
be caused by the elevation of the pressure within the chamber to
above the first condition. This may correspond to a positive
pressure gradient or differential existing between the interior of
the chamber and the fluid pressure at the end of the puncture
member.
[0019] The chamber may comprise one or more deformable walls or
formations, which may be actuable in response to the pressure
within the chamber. The chamber may comprise a diaphragm. Movement
of the diaphragm may trigger the retraction mechanism. A diaphragm
has been found to provide a particularly sensitive and responsive
trigger/actuator in response to typical vascular fluid pressures.
The volume of the chamber and size of the diaphragm, as well as the
diaphragm material/mass, can all be tailored to suit a desired use,
such as intravenous cannulation.
[0020] The retraction of the puncture member may be automatic upon
experiencing a pressure at or beyond a predetermined pressure
difference from ambient. The retraction mechanism may actuate the
puncture member in response to a predetermined positive or negative
pressure differential. Advantageously, the device does not require
pre-pressurisation for correct operation and can be ready for use
at an ambient internal pressure.
[0021] In one embodiment, the device comprises a housing for the
retraction mechanism and the puncture member depends from the
housing such that the free end of the puncture member is spaced
from the housing. The puncture member may be insertable into a
sleeve such that the sleeve abuts against the housing. The puncture
member and/or housing may be arranged to form a friction fit with
the sleeve in use. The housing may comprise one or more formations
for fitment with the sleeve member. A push-fit or twist-fit
engagement formation may be provided on the housing.
[0022] The retraction mechanism may comprise a chamber and an
engagement member which may be releasably engageable with the
puncture member in response to change in the fluid pressure within
the chamber. The hollow puncture member may have an opening spaced
from the end of the puncture member. The opening may open into the
chamber so as to allow fluid communication between the end of the
puncture member and the chamber. Accordingly a fluid pressure at
the end of the needle may be experienced in the chamber.
[0023] The retraction mechanism may comprise an actuator which is
arranged to move the engagement member selectively out of
engagement with the puncture member in response to the pressure
within the chamber. The puncture member may be biased towards the
second condition, for example by a spring. The biasing means may be
coupled between the puncture member and the chamber and/or
retraction mechanism housing. The engagement member may hold the
puncture member against the biasing force of the biasing means and
may allow retraction of the puncture member when disengaged
there-from.
[0024] The puncture member may comprise an engagement formation for
cooperation with the engagement member. The engagement member may
comprise a protrusion depending radially outwardly from the
puncture member.
[0025] The retraction mechanism may comprise a stop member to
prevent further retraction of the puncture member beyond a
predetermined distance. The stop member may be arranged to abut
against the engagement formation of the puncture member in the
second condition. The positioning of the stop member advantageously
allows for reliable retraction of the puncture member by a
predetermined distance.
[0026] The retraction mechanism may comprise a, inflatable member,
such as a diaphragm member coupled to, or formed with, the chamber,
which is moveable in response to the fluid pressure in the chamber.
The engagement member may be actuable by the inflatable member and
may be attached thereto or depend there-from. The inflatable member
or diaphragm member may serve as a pressure sensor.
[0027] Additionally or alternatively the retraction mechanism may
comprise an electronic pressure sensor for detecting fluid pressure
within the chamber. In such an embodiment, the actuator may
comprise an electrically or electronically operated actuator.
[0028] The puncture member may be elongate in form and may have a
longitudinal axis. The retraction mechanism may actuate the
puncture member between the first and second conditions in a
substantially axial direction.
[0029] In one embodiment, the device comprises the sleeve. The
sleeve may have an open end, through which the puncture member
protrudes in the first condition. The open end of the sleeve may be
immediately adjacent the end of the puncture member in the first
condition. The sleeve is preferably a close or tight fit about the
puncture member at its end. In the second condition, the sleeve and
the housing preferably remain fastened together at a location
spaced from the end of the puncture member. The puncture member is
typically elongate in form and has a second end which is supported
within the housing.
[0030] The puncture member and sleeve are typically formed of
different materials. The puncture member may be formed of metal
whereas the sleeve may be formed of a polymer material. In
alternative embodiments, the puncture member and sleeve may be
formed of the same material, such as, for example, a metal. Such an
embodiment may comprise a two-part needle arrangement.
[0031] In one embodiment, the device comprises a medical device
which may take the form of a cannula insertion device. The sleeve
may comprise a cannula, which may be a ported cannula.
[0032] It will be appreciated by the skilled person that the term
"vessel" used herein may constitute a conduit, a cavity or a
reservoir and should be construed accordingly.
[0033] Practicable embodiments of the invention are described in
further detail below with reference to the accompanying drawings,
of which:
[0034] FIG. 1 shows a three-dimensional view of an assembly
comprising a device and sleeve according to a first embodiment of
the present invention;
[0035] FIG. 2 shows the assembly of FIG. 1 with the device and
sleeve disassembled;
[0036] FIG. 3 shows a longitudinal section through the assembly of
FIG. 1 in a first condition;
[0037] FIG. 4 shows a three dimensional view of the longitudinal
section of FIG. 3;
[0038] FIG. 5 shows a longitudinal section of the assembly of FIG.
1 in a second condition;
[0039] FIG. 6 shows a three-dimensional view of an alternative
arrangement between the actuator and puncture member according to a
second embodiment of the invention;
[0040] FIG. 7 shows a longitudinal section through the assembly
according to the second embodiment in a first condition;
[0041] FIG. 8 shows a longitudinal section through the assembly
according to the second embodiment in a second condition;
[0042] FIG. 9 shows a three-dimensional view of an assembly
comprising a device, a sleeve and a cover according to a third
embodiment of the present invention;
[0043] FIG. 10 shows a longitudinal section through the device
according to the third embodiment in a first condition;
[0044] FIG. 11 shows a longitudinal section through the device
according to the third embodiment in a second condition;
[0045] FIG. 12 shows a three-dimensional view of an assembly
comprising a device and sleeve according to a fourth embodiment of
the present invention;
[0046] FIG. 13 shows a longitudinal section through the assembly of
FIG. 12 in a first condition;
[0047] FIG. 14 shows a longitudinal section through the assembly of
FIG. 12 in a second condition;
[0048] FIG. 15 shows a three-dimensional view of an assembly
comprising a device and sleeve according to a fifth embodiment of
the present invention;
[0049] FIG. 16 shows a longitudinal section through the assembly of
FIG. 15 in a first condition;
[0050] FIG. 17 shows a longitudinal section through the assembly of
FIG. 15 in a second condition;
[0051] FIGS. 18A and 18B show further optional features of a
puncture device according to the invention; and,
[0052] FIG. 19 shows an additional or alternative safety feature to
the arrangement of FIG. 18.
[0053] The invention to be described below derives from the
conception of an automatic mechanism to cause withdrawal of the
puncture device out of a fluid vessel once a sleeve is correctly
positioned for communication with the fluid vessel. In the case of
a medical device for insertion of a sleeve such as a cannula into a
fluid vessel within a body, the device is triggered when the needle
moves from surrounding tissue into the vessel. This removes the
need for the operator to manually retract the needle upon
determination of the correct location of the needle in, for example
a vein. The automation of this part of the process mitigates
against a major cause of cannula insertion failure due to poor
detection of the instant the vein is punctured.
[0054] This invention may trigger automatic withdrawal of the
puncture member as soon as the sleeve is inserted into the vessel
based on the change in pressure between the fluid in the vessel and
the fluid or other matter outside of the vessel.
[0055] Whilst the invention finds particular use in the insertion
of a conduit into a fluid vessel in the body, it is not limited to
vascular access applications and may be used in other instances
where it is necessary to undertake such an operation with minimal
loss of fluid and/or where manual control of the operation is prone
to potential failure.
[0056] Turning to FIGS. 1 to 5 there is shown a first embodiment of
an assembly 10 and device 12 according to the invention, which may
be used for percutaneous vascular access. The assembly 10 generally
comprises a puncture device 12 and sleeve arrangement 14. The
device comprises a housing 16 and a puncture member 18, in the form
of a needle, depending there-from.
[0057] The sleeve arrangement 14 takes the form of a cannula which
may be conventional in design, having an elongate plastic or metal
tube 20 depending from a support formation 22. The tube 20 is of
generally constant diameter but with a tapered formation towards
its free end 24. The tube 20 has a longitudinal axial bore which
opens into the interior of the support formation 22 such that the
sleeve arrangement is substantially hollow along its entire length.
The bore through the support formation is of greater diameter than
that through the tube formation and has a tapered wall 26 by way of
a neck portion which joins a tube-engaging end of the support
formation to its main body.
[0058] The sleeve arrangement 14 also comprises lateral protrusions
in the form of lobes 28 depending outwardly from the longitudinal
axis which are located against the surface of a patient's skin
during use.
[0059] The sleeve arrangement in this embodiment is `ported` in
that it has a further port 30 depending substantially radially
outwardly from the body of the support formation. The port 30
provides a side duct which feeds into the cavity of the support
formation to allow fluid communication with the tube 24. In
alternative embodiments, this duct 30 may be omitted.
[0060] The device 12 comprises a recess 31 about the region of
entry of the needle 18 into the housing 16. The recess 31 is shaped
to form a friction fit about the open end of the support formation
22 of the sleeve 14. The recess 31 may be slightly tapered or
otherwise shaped to provide a tight fitment with the sleeve 14. In
alternative embodiments, the sleeve and/or housing 16 may comprise
corresponding fixing formations so as to allow for a twist-fit
engagement there-between.
[0061] The sleeve 14 is fixed to the housing for use in a manner
shown in FIG. 1, such that the needle tip 18A protrudes slightly
beyond the free end 24 of the cannula tube 20. In this regard, the
needle end 18A is tapered to provide a sharp puncturing formation
at the end of a main tube portion which is of substantially
constant diameter along its length. The taper in the tubular needle
construction forms an end opening, which is obliquely oriented
relative to the longitudinal axis of the needle, and which is
generally elliptical in plan. The sleeve end 24 is arranged in use
as close a practicably possible to the edge of the opening in the
needle at end 18A.
[0062] The arrangement of the sleeve 14 and the connection thereof
to the device 10 is generally common to all embodiments to be
described in relation to FIGS. 3-17 below and will not be repeated
for conciseness. Whilst the invention is primarily concerned with
the operation of the device itself, the device is configured for
use with such a sleeve and is typically distributed as an assembly
in which the device and sleeve 14 are assembled in a ready-to-use
condition.
[0063] Turning now to FIGS. 3-5, the device 12 and its operation
with respect to the sleeve will now be described.
[0064] The device housing 16 is shaped so as to define an internal
chamber 32. The chamber 32 has front 34 and rear 36 end walls with
openings therein aligned with the longitudinal axis of the needle
18 and shaped to closely surround the needle 18 in a fluid tight
manner. In this embodiment, the chamber 32 is generally cylindrical
in shape although it need not be limited to such a
configuration.
[0065] On the opposing side of the rear wall 36 to the chamber 32
is a rear bore or recess 38, defined by a rearwardly extending
cylindrical portion 40 of the housing 16. A body 42 in the form of
a bung or stop is located in the recess 38 and is moveable in an
axial direction there-in. The body 42 is biased in a rearward,
retraction direction (as shown by arrow A) by biasing member 44,
which in this embodiment takes the form of a coiled spring. The
body 42 is braced against the internal wall 36 of the housing, with
the spring 44 trapped in compression there-between.
[0066] The needle 18 is elongate in form and extends from end 18B
which is mounted in the housing 16, specifically in the body 42
within the housing, through the chamber 32 and the walls 34 and 36
thereof to its free end 18A which is spaced from the housing.
Accordingly the needle is mounted in the housing and depends
there-from.
[0067] Within the portion of the needle 18 that passes through the
housing chamber 32, there is provided an opening 46, part way along
its length.
[0068] The portion of the needle 18 that is within the housing
chamber 32 is also provided with an engagement formation 48 which
depends radially outwardly from the needle body. The engagement
formation may take the form of a tapered or ramped stop member,
which may be frusto-conical in shape.
[0069] The chamber 32 communicates with a further chamber 50, which
is typically larger in width, via a throat formation 52. The
further chamber is defined by a base portion and a peripheral wall
54 which is upstanding from the remainder of the housing 16 and
which is generally circular in plan. In alternative embodiments,
the chamber need not be cylindrical but may take any suitable shape
in order to allow a sufficient size of diaphragm to be
accommodated. The base and upstanding wall 54 are integrally formed
with the remainder of the housing 16.
[0070] The chamber 50 is sealed from the outside of the device by a
diaphragm 56 (omitted from FIG. 4), which is attached about the
peripheral face of the wall 54. The diaphragm comprises a
deformable material, such as a polymer, so as to allow movement
thereof in response to pressure changes between the interior of the
chamber 54 and the exterior of the device. The diaphragm is
typically shaped according to the shape of the chamber 50.
[0071] The diaphragm is typically offset from the longitudinal axis
of the device and/or needle. The diaphragm may be actuable in a
direction which is substantially perpendicular to such an axis. The
diaphragm and chamber may be greater in width than the remainder of
the device.
[0072] The diaphragm 56 is sandwiched between opposing discs 58
which provide further rigidity to the diaphragm assembly.
Protruding from the outer disc 58 towards the needle 18, there is
provided an engagement formation in the form of a pin 60. In this
embodiment, the pin 60 is integrally formed with the outer disc 58
and extends through the diaphragm 56 and inner disc towards the
chamber 32. A guide formation is provided within the throat 52,
through which the pin 60 extends.
[0073] Whilst chambers 32 and 50 are formed within the housing as
separate chambers, connected by throat 52, it will be appreciated
that those chambers are maintained at a substantially uniform
pressure and accordingly those chambers may be combined in an
alternative embodiment.
[0074] In the first condition shown in FIG. 3, the pin 60 engages
with the engagement formation 48 of the needle 18 and prevents
retraction of the needle by the spring 44. Thus the device is in a
primed condition, ready for insertion into a fluid vessel. In this
condition, the needle tip 18A protrudes beyond the free end of tube
20 in the manner described above. The pressure within chambers 32
and 50 are equal to the exterior pressure since the chambers
communicate with the outside of the device via the needle bore and
opening 46 therein. Accordingly the diaphragm is in an at rest
condition since the pressure inside and outside the device is
equalised.
[0075] In use, the tip of the needle 18A and associated cannula 20
is inserted into the body of a patient. As the needle tip 18A
passes through tissue, the pressure inside the device does not
substantially change since little or no fluid enters the needle 18.
However once the needle enters a fluid vessel in the body, by
piercing the vessel wall, the interior chambers 32 and 50 are
exposed to the fluid pressure within the vessel.
[0076] The passage of fluid through fluid vessels requires a fluid
pressure differential to exist. Accordingly, upon the entry of the
needle tip 18A into the fluid vessel, a pressure gradient is
established between the chambers 32, 50 and the vessel interior. In
the example of a blood vessel, such as a vein, or other `flowing`
vessel, the pressure in the vessel is typically greater than
ambient pressure (i.e. the pressure within the device 12).
Accordingly fluid will tend to flow into the chambers 32, 50 and
thereby actuate the diaphragm by inflation.
[0077] The actuation of the diaphragm away from the needle 18 (i.e.
by inflation) causes the pin 60 to move radially away from the
needle axis and thereby disengage the engagement formation 48. Once
disengaged, the needle moves axially rearward under the biasing
force of the spring 44 on the body 42 until the engagement
formation 48 abuts against chamber wall 36. Thus the needle is
retracted relative to sleeve 14 by a predetermined distance (i.e.
the distance between the engagement formation 48 and the wall 36 in
FIG. 3), so as to achieve the condition shown in FIG. 5.
[0078] The increase in pressure in the chambers 32, 50 may be
achieved by the flow of fluid from the vessel into the chambers
and/or compression of any existing fluid (e.g. air) which may
already be present in the chambers. Also the required distance of
travel of the pin is relatively small. Accordingly the device is
particularly sensitive and requires only a minimal fluid flow for
actuation.
[0079] FIG. 5 represents the deployed condition in which the needle
end 18A is contained within the tube 20 and the body 42 protrudes
rearwardly beyond the end of the housing 16. The diaphragm is
maintained in its actuated condition. The body 42 in this condition
also advantageously provides a visual indication to a user that the
needle has been retracted. In this regard the body 42 may be
coloured or otherwise marked such that it is clearly visible once
it protrudes beyond the housing 16. However in alternative
embodiments, the body 42 may not protrude beyond the end of the
housing 16 such that the actuation of the device cannot be
inadvertently hindered by an operator.
[0080] The retraction of the needle 18 as described above leaves
the tube 18, in this embodiment, the cannula, correctly located in
the fluid vessel. The actuation pressure and spring force involved
are sufficiently small that there is minimal disturbance to an
operator holding the device 12. It is also advantageous that the
needle is at the same time made temporarily safe, such that it is
no longer exposed and cannot accidentally puncture the fluid vessel
further.
[0081] The device 12 is removed from the sleeve 14 completely. The
sleeve arrangement 14 can be secured in place against a patient's
skin in a conventional manner, such that the cannula remains in
place against the patient's skin for further use, such as the
administration of fluid to, or else removal of fluid from, the
vessel. The sleeve is typically secured after removal of the device
12 but may be secured whilst the device remains assembled therewith
if necessary.
[0082] The embodiment above utilises a disc-shaped diaphragm to
effect movement of the release pin when the fluid pressure reaches
a certain threshold. The rigid disc components above and below the
diaphragm ensure that there is uniform inflation of the diaphragm,
and hence a predictable effect on the release pin.
[0083] Sensitivity of the device to fluid pressure differentials is
important to correct operation, and the desired sensitivity is
achieved by tailoring the enlarged area of the diaphragm such that
it can actuate the mechanism under relatively low pressures, whilst
avoiding unwanted actuation of the device when not in use.
[0084] In an alternative embodiment, it is possible that a stack of
diaphragms could be used to increase sensitivity in addition to, or
instead of, the enlarged area diaphragm shown in FIGS. 1-5. This
may help reduce the overall size of the device.
[0085] In order to further increase the accuracy with which the
device can operate, the underside of the needle tip 18A (in the
orientation shown in FIG. 3) may be provided with a small opening
such that fluid can escape the needle up until the point at which
the whole of the needle opening is located in the vessel. This
secondary opening in the wall of the main end opening of the
puncture member can prevent early actuation of the device as the
puncture member enters the vessel. It is important that the end of
the cannula has entered the vessel when the fluid pressure
increases within the needle, and hence the needle retracts, in
order that the cannula is successfully inserted into the vein. The
secondary opening in the wall of the needle may be provided
immediately adjacent to the cannula end.
[0086] In FIGS. 6-8, there is shown a further embodiment of the
invention, which allows for actuation of the device 12 when the
puncture member 18 is inserted into a fluid vessel of lower
pressure than that in the chambers 32, 50 within the device. The
construction of device 12A of FIGS. 6-8 is the same as the device
of FIGS. 1-5 described above save that the engagement pin 60 is
provided with a head formation 62 as shown in FIGS. 6-8.
[0087] The head formation 62 has a pair of adjoining apertures 64,
66 therein. The first aperture 46 has a diameter which is slightly
larger than the diameter of the needle 18 but less than that of the
engagement formation 48. The second aperture 66 adjoins the first
aperture 64 and has a diameter which is greater than that of the
first aperture and the engagement formation 48. The first aperture
64 is located furthest from the disc 58 (i.e. towards the outer end
of the head formation 62), whilst the second aperture 66 is located
between the first aperture and the disc (i.e. proximate the pin
shaft 60).
[0088] In the first, primed, condition shown in FIGS. 6 and 7, the
head formation 62 engages the engagement formation 48 of the pin 18
against the biasing force of the spring 44 in a manner similar to
that of FIG. 3. However, in use, when the needle tip 18A of the
device 12A is inserted into a fluid vessel of lower pressure than
that inside the device 12A, the diaphragm will experience a
negative pressure differential, thereby causing actuation of the
diaphragm 56 and disc 58 towards the needle axis as shown in FIG.
8.
[0089] The actuation of the diaphragm, disc 58 and the associated
head formation 62 as shown in FIG. 8 causes the larger aperture 66
to become aligned with the engagement formation 48, thereby
disengaging formation 48 and allowing retraction of the needle into
the second condition shown in FIG. 8 until the engagement formation
48 abuts the chamber wall 36.
[0090] Accordingly the changing of the engagement member 60 can
allow for the device to operate under positive or negative pressure
differentials. This allows application of the present invention to
a wider variety of anatomical vessels, including cavities having a
fluid pressure which is typically below atmospheric pressure.
[0091] Turning now to FIG. 9, there is shown two further
embodiments of an assembly according to the present invention,
which comprise the device 12 or 12A of either the first or second
embodiment described above. The embodiment of FIGS. 9-11 is
provided with a cover, which is formed of a rigid material, such as
the plastic used to form the housing 16. The cover is shaped to be
attached about the peripheral wall 54 of the device such that it
covers the diaphragm 56 and disc 58.
[0092] The cover acts as a lid or cap and is shaped to form an
internal space between the diaphragm 56, including disc 58 and the
cover so as to allow movement of the diaphragm in use. The cover
prevents access to the diaphragm which may cause unwanted or
accidental actuation of the diaphragm 56 prior to the intended use
of the device.
[0093] Although not shown in FIG. 9A, the cover will typically have
an air inlet to ensure that the outer face of the diaphragm is
exposed to ambient pressure. The size of this air inlet will affect
the response of the diaphragm to changes in the needle fluid
pressure, and hence the air inlet may be variable in size to enable
adjustment of sensitivity, although it is generally preferred to
avoid choking of any flow to, or from, the diaphragm through the
cover to achieve a short time delay in the actuation of the
device.
[0094] One embodiment of such an adjustable cover is shown in FIG.
9B, for which the cover comprises first and second cover members
67A and 67B. The cover member 67B is seated over the diaphragm and
associated chamber of the device. The cover member 67A is of
slightly larger size than cover member 67B such that it can be
located over the cover member 67B. Both cover members have an
aperture therein 69 such that the degree of overlap between the
apertures of the cover members 67A and 67B determines the size of
the window or air inlet. The cover 67A can thus be rotated to
adjust the aperture size. The apertures 69 in the cover members are
preferably elongate in form and circumferentially aligned to
facilitate easy and accurate adjustment thereof.
[0095] The cover 66 in the embodiment of FIGS. 9A, 10 and 11 also
includes means for adjusting the resistance of the diaphragm to
motion by way of biasing member 68, in the form of a spring. The
spring may resist motion under the compression, or extension, of
the spring such that, in order to actuate the device, the pressure
differential must be sufficient to overcome the resilience of the
spring. The spring may also serve to dampen the motion of the
diaphragm and ensure a smooth operation of the device.
[0096] The spring 68 is mounted on an adjustable shank 70 which is
received in a corresponding port in the cover 66. Thus the
resilience offered by the spring 68 can be adjusted so as to allow
adjustment of the threshold pressure at which the device is
actuated between the first and second conditions. In this example,
the shank 70 and cover aperture are correspondingly threaded. The
shank is provided with a thumb screw or knob formation 72 or
similar manual adjustment formation such that the degree of
compression or extension of the spring 68 can be easily adjusted by
hand. One or more indicia may be provided on the cover to show
pre-set threshold condition such that an operator can adjust the
formation 72 by a set number of turns or fractions of a turn to
achieve the desired threshold setting. The features of FIGS. 9A-11
and FIG. 9B may be combined.
[0097] In FIGS. 12-14, there is shown a further embodiment 12B of
the invention which is the same as that of any of FIGS. 1-8
described above, save that the modified device housing 16B no
longer has the chamber 50, nor the diaphragm 56 or associated discs
58. Instead, the chamber 32B has been modified to house a different
type of diaphragm, in the form of balloon 74, which may be
considered to provide a longitudinal or concave type diaphragm. In
the first, un-actuated, condition the balloon only partially fills
the chamber 32B. The balloon 74 may be formed of a material similar
to that used for inflation of stent balloon devices as is known in
the field of medical apparatus. The balloon is provided with one or
more rigid ribs or rods 76, which support the engagement formation
60B, and which are arranged substantially parallel with the
longitudinal axis of the needle 18. The ribs may accordingly be
considered to be longitudinal in design.
[0098] Also the device housing 16B has a number of apertures 75
therein. The device also comprises a cover in the form of collar,
or partial-collar, member 77 with corresponding apertures therein.
The position of collar 77 on housing 16B is adjustable so as to
vary the size of the opening to allow fluid communication with the
exterior of the balloon 74 such that the balloon can freely inflate
and deflate in a manner similar to that described in relation to
FIG. 9 above. The collar 77 is moveable in an axial direction in
this embodiment but alternative actuation of the cover is feasible
dependent on the shape and orientation of the apertures.
[0099] The embodiment of FIGS. 12-14 operates in a manner similar
to that of FIG. 3-5 or 6-8 described above such that the pressure
differential caused by insertion of the needle into a fluid vessel
causes inflation or collapse of the balloon 74 so as to release the
engagement formation 48 and thereby allow retraction of the needle
18 into the sleeve.
[0100] Other embodiments of inflatable, or pressure sensitive,
actuation devices will be apparent to the skilled person as
alternatives to the embodiments described above and may be
substituted for the actuation mechanisms described above provided
the required pressure sensitivity characteristics can be achieved.
Such embodiments may, for example comprise a bellows configuration
or a low-friction piston arrangement.
[0101] Turning now to FIGS. 15-17 an alternative embodiment 100 is
shown, which allows for electronic control of the actuation of the
device instead of the purely mechanical sensing and actuation means
proposed in the above-described embodiments.
[0102] The embodiment 100 of FIGS. 15-17 is similar in construction
and operation to the embodiments described above, save for the
following differences.
[0103] The housing 116 has been modified to provide a single
internal chamber 132, in which is mounted an electronic pressure
sensor 101. A processor is provided (not shown) to compare the
pressure sensed by sensor 101 to a preset threshold pressure and to
control operation of an actuator when the sensed pressure meets or
exceeds the threshold value. The processor may take the form of a
simple comparator or else a more complicated programmable chip
dependent on the level of sophistication required for the intended
operation. The actuator in such an embodiment may comprise an
electric or electronic actuator such as, for example, a solenoid
103, which is arranged to displace engagement member 160 in a
manner similar to that described above. A power source such a
batter will typically also be provided to power the actuation
mechanism.
[0104] Whilst the embodiments described above make use of a
continually biased needle arrangement, since it allows for
actuation of the needle under a relatively small pressure
differential, as will typically be experience in medical
applications, it is also possible the actuator may displace the
needle directly, rather than disengaging a latching means for the
needle. For example, in an electronically controlled embodiment in
particular, a solenoid or other powered actuator will typically be
sufficient to drive the retraction of the needle itself in a
reliable manner without the need to bias the needle to a retracted
condition in advance.
[0105] The threshold pressure may be different for different
patients. However, it is likely that the device will have a
standard threshold, although possibly with a setting for low
pressure patients (such, as for example, for elderly patients or
those suffering blood loss). The fluid pressure may also be higher
than normal vein pressure, due to the presence of a tourniquet, and
the threshold pressure may be adjusted or preset accordingly. A
value of between 15-25 mm Hg and, typically around the value of 20
mm Hg, hydrostatic pressure is proposed as being a normal
threshold.
[0106] Turning now to FIGS. 18A and 18B, there is shown the device
12 of FIGS. 1-5 comprising a safety feature to allow the needle 18
to be made safe after use. In this example, the device housing 16
is formed of two parts 16A and 16B. The needle 18 is mounted in
part 16B. The two housing parts 16A and 16B are firmly held
together during use of the device but are detachable. This may be
achieved by an attachment arrangement similar to that described
above between the device 12 and sleeve arrangement 14 and may
comprise a frictional engagement, such as a push-fit engagement,
between correspondingly shaped and/or closely fitting formations.
Other conventional engagement arrangements, such as a twist-fitting
or locking engagement, may be used.
[0107] After the device has been used as described above, the
housing part 16B, in which the needle is mounted, can be pulled
apart from housing part 16A until the end 18A of the needle is
located within the housing part 16A. Thus the device is made safe
for disposal. A simple mechanism, such as a spring loaded plate,
can be used to limit the available distance of separation of the
housing parts 16A and 16B and/or to lock the needle in its
made-safe condition within housing portion 16A.
[0108] Turning now to FIG. 19, optional features of the device of
any preceding embodiment are shown in an enlarged window. The
needle 18 may comprise a sheath or tube 200 which is concentric
therewith and extends in the same axis as the needle. The tube 200
is blunt at its free end and may be formed of a suitable plastic or
other material. The tube is mounted at its fixed end 202 within the
device 12. However, unlike the needle 18, the tube 200 is fixedly
attached to a rigid portion of the device housing 16, such as an
internal wall thereof (e.g. wall 34 or 36) and is not actuable
thereto.
[0109] The tube is maintained within the sleeve 20.
[0110] In use, the needle end 18A protrudes beyond the free end 204
of the tube. In this condition, the free end 204 of the tube is
also behind the free end 24 of the sleeve 20 such that it does not
interfere with the operation of the device as described above.
However, upon retraction of the needle, the needle is actuated
relative to the fixed tube such that it is withdrawn beyond the
free end 204 of the tube. Thus when the device 12 is removed from
the sleeve arrangement after use, the needle end 18A remains within
the tube 200, thereby avoiding accidental injury which may be
caused by the exposed needle.
[0111] In the manner described above in relation to FIGS. 18 and/or
19, any of the embodiments of the invention described above can be
provided with an anti-stab, or made-safe, feature.
[0112] The different medical uses for which the present invention
may be applicable comprise, for example, intravenous cannulation,
aspiration/drainage of fluids within body cavities (e.g. pleural
effusions, ascites), and/or laporoscopy trochar. The cannula may
also be substituted for an alternative sleeve, such as a metal
sleeve for use as a two-part needle arrangement. It is also
envisaged that the invention may be applicable to wider engineering
use where a conduit is required to be placed in communication with
an existing fluid vessel by first puncturing the vessel.
[0113] In any of the foregoing embodiments, the chamber within the
housing may comprise a transparent material portion in the form of
a window or the like so as to provide in use an indication to the
operator that a fluid has entered the chamber. The use of such a
visual indication of fluid entering the chamber provides a
beneficial second means for checking correct operation of the
device. Accordingly an operator can visually check correct
deployment of the device using both the projection, to determine
that the device has actuated, and also the window, to determine
that fluid communication between the vessel and the chamber has
been achieved.
[0114] The visual confirmation of one indication in the absence of
the other may infer incorrect or incomplete operation of the device
such that an operator can attempt to reposition the device, or
undertake other steps to ensure correct operation, prior to
removing the puncture member. In the event that fluid is seen via
the window but the retraction mechanism has not actuated, the
operator may manually retract the puncture member by withdrawing it
from the sleeve so as to complete the operation.
[0115] In further embodiments, the device may comprise an
additional or alternative alerting means such as an electronic
system to sense retraction of the needle and alert the operator by
way of a visual or audible indicator.
* * * * *