U.S. patent application number 09/766361 was filed with the patent office on 2001-06-07 for fluid jet cutting system.
Invention is credited to Coffin, C. Ronald, Moutafis, Timothy E., Patterson, Frank Van, Yoder, Marvel John.
Application Number | 20010002562 09/766361 |
Document ID | / |
Family ID | 23933015 |
Filed Date | 2001-06-07 |
United States Patent
Application |
20010002562 |
Kind Code |
A1 |
Moutafis, Timothy E. ; et
al. |
June 7, 2001 |
Fluid jet cutting system
Abstract
A system for generating a high pressure fluid jet includes a
variable pressure pump and a burst resistant delivery tube which
safely conducts the pressurized stream to an instrument. The pump
may include a disposable diaphragm pump cartridge which is driven
by a reusable pump. The delivery tube may be a coiled hypo tube
which enhances flexibility.
Inventors: |
Moutafis, Timothy E.;
(Gloucester, MA) ; Coffin, C. Ronald; (Topsfield,
MA) ; Patterson, Frank Van; (Exeter, NH) ;
Yoder, Marvel John; (Andover, MA) |
Correspondence
Address: |
Timothy J. Oyer
Wolf, Greenfield & Sacks, P.C.
600 Atlantic Avenue
Boston
MA
02210
US
|
Family ID: |
23933015 |
Appl. No.: |
09/766361 |
Filed: |
January 19, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09766361 |
Jan 19, 2001 |
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08486725 |
Jun 7, 1995 |
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6216573 |
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Current U.S.
Class: |
83/13 ;
83/177 |
Current CPC
Class: |
Y10T 83/04 20150401;
A61B 2017/32032 20130101; Y10T 83/0453 20150401; Y10T 83/364
20150401; B26F 3/004 20130101; A61B 17/3203 20130101 |
Class at
Publication: |
83/13 ;
83/177 |
International
Class: |
B26D 001/00; B26D
007/00; B26F 003/00 |
Claims
What is claimed is:
1. A pumping system comprising: a reusable component; and a
disposable diaphragm pump mounted in operative association with the
reusable component and being constructed and arranged to generate a
high pressure fluid cutting jet, the disposable diaphragm pump
including: a pump cartridge; a diaphragm; and an annular seal in
contact with a periphery of said diaphragm and a surface of said
pump cartridge when the diaphragm pump is mounted in operative
association with the reusable component, said annular seal
constructed of a flexible material having a modulus of elasticity
of a first value when the disposable diaphragm pump is not mounted
in operative association with the reusable component and having a
modulus of elasticity of a second value when the diaphragm pump is
mounted in operative association with the reusable component, said
second value being substantially greater than said first value and
being within a range of moduli of elasticity typical for hard
plastics soft metals.
2. The pumping system recited in claim 1, wherein said pump
cartridge and said diaphragm define a pumping chamber
therebetween.
3. The pumping system recited in claim 1, wherein the reusable
component engages both the pump cartridge and the diaphragm and
secures the pump cartridge to the diaphragm.
4. The pumping system recited in claim 2, wherein said annular seal
forms a leaktight barrier between the diaphragm and the pump
cartridge such that the pumping chamber is able to withstand fluid
operating pressures of at least 1000 p.s.i, without fluid leakage
through the leaktight barrier.
5. The pumping system recited in claim 1, wherein the pump
cartridge includes an inlet disposed therein, through which a
cutting fluid is communicated from a source to the pumping chamber,
and an outlet disposed therein, through which the cutting fluid
passes from the pumping chamber.
6. The pumping system recited in claim 1, wherein said annular seal
is integrally formed with the of the diaphragm and wherein the
annular seal and the diaphragm are constructed from the same
material.
7. The pumping system recited in claim 1, wherein said surface of
said pump cartridge includes an annular channel therein, with said
annular seal being seated in said channel.
8. The pumping system recited in claim 7, wherein said annular seal
and said annular channel have different cross-sectional shapes.
9. The pumping system recited in claim 8, wherein said annular seal
has a circular cross-sectional shape and said annular channel has a
square cross-sectional shape.
10. The pumping system recited in claim 1, wherein said reusable
component exerts a working force on said diaphragm, when the system
is in operation.
11. The pumping system recited in claim 10, wherein said working
force is essentially uniformly applied to an external surface of
said diaphragm that is deformed by said working force.
12. A pumping system comprising a reusable component; and a
disposable diaphragm pump mounted in operative association with the
reusable component and being constructed and arranged to generate a
high pressure fluid cutting jet, the disposable diaphragm pump
including: a pump cartridge; and a diaphragm; said reusable
component comprising a piston pump including a force applicator
constructed and arranged to exert a working force on said
diaphragm, said working force being essentially uniformly applied
to an external surface of the diaphragm that is deformed by the
working force when the system is in operation.
13. The pumping system of claim 12, wherein said pump cartridge and
said diaphragm define therebetween a pumping chamber.
14. The pumping system of claim 13, wherein said working force is
sufficient to create a fluid operating pressure of at least 1000
p.s.i. within said pumping chamber.
15. A method for pumping a fluid with a disposable diaphragm pump,
said diaphragm pump comprising a pump cartridge and a diaphragm,
the method comprising: supplying a fluid to a pumping chamber
within said diaphragm pump through an inlet disposed in said pump
cartridge; increasing a pressure of the fluid supplied to the
pumping chamber to at least 1000 p.s.i. by applying a working force
to a surface of said diaphragm; and passing the fluid from the
pumping chamber through an outlet disposed in the pump
cartridge.
16. The method as recited in claim 15, further comprising before
the supplying step, the step of: mounting the disposable diaphragm
pump in operative association with a reusable component.
17. The method as recited in claim 16, wherein during the mounting
step, the reusable component engages both the pump cartridge and
the diaphragm and secures the pump cartridge and the diaphragm to
each other.
18. The method as recited in claim 17, wherein a leaktight barrier
is formed between the pump cartridge and the diaphragm during the
mounting step.
19. The method as recited in claim 16, wherein during the
increasing step, said working force is exerted by the reusable
component.
20. The method as recited in claim 19, wherein said working force
is applied essentially uniformly to a surface of the diaphragm
deformed by application of the working force.
21. The method as recited in claim 20, wherein the reusable
component exerts said working force on the diaphragm by exerting a
force on a working fluid contained in the reusable component, the
working fluid being in contact with the pumping chamber and
isolated from the fluid supplied to the pumping chamber during the
supplying step.
22. The method as recited in claim 15, further comprising after the
increasing step the step of: varying and controlling the pressure
of the fluid passed from the pumping chamber during the passing
step.
23. The method as recited in claim 15, further comprising after the
passing step the steps of: communicating the fluid passed from the
pumping chamber through a delivery tube to an instrument having a
jet orifice; and creating a fluid cutting jet by flowing the fluid
through the jet orifice.
24. The method as recited in claim 23, further comprising after the
creating step the steps of: directing the fluid cutting jet toward
a tissue of a patient; and cutting the tissue with the fluid
cutting jet.
Description
RELATED APPLICATIONS
[0001] This application is a divisional of application Ser. No.
08/486,725, filed Jun. 7, 1995, entitled FLUID JET CUTTING SYSTEM,
and now pending.
FIELD OF INVENTION
[0002] This invention relates to pumping systems usable in fluid
jet cutting systems, to components of such systems and to a method
of pumping a fluid with a disposable diaphragm pump.
BACKGROUND OF THE INVENTION
[0003] Fluid jet cutting systems are known which employ high
pressure streams of liquid, such as water, as the cutting force.
High pressure fluid jet cutting systems also have been proposed for
use in surgical applications. U.S. Pat. No. 3,930,505 discloses a
variable pressure jet for disintegrating eye lens tissue. A system
for use in hepatobiliary surgery, known as the Hepatom, has been
reported in the literature and may be available outside of the
United States. U.S. Pat. No. 5,370,609, and related European patent
applications 0 485 133 and 0 489 496, describe a water jet catheter
which delivers a high pressure liquid stream to dislodge, emulsify
and remove deposits from a vein or artery.
SUMMARY OF THE INVENTION
[0004] The present invention is a system for generating a high
pressure fluid jet including a variable pressure pump for creating
the high pressure fluid and a burst resistant delivery tube for
safely conducting the pressurized stream. The pump may include a
disposable diaphragm pump which is driven by a reusable pump, such
as a piston pump or an air intensifier unit. The pumped fluid
communicates only with the disposable diaphragm component, allowing
contamination free reuse of the system by simply replacing a spent
diaphragm unit with a fresh, sterile disposable pump. An instrument
or wand having one or more orifices for creating a jet may be
connected to the distal end of the delivery tube. Alternatively,
the jet instrument may embody a burst resistant catheter having a
jet tip. The delivery tube may be coiled, enhancing the flexibility
of the tube and the ease of handling by a user. A high pressure
seal may be formed between the delivery tube and the outlet of the
pump and between the nozzle and the delivery tube. The seal may be
provided in a hand-tightenable connector where one or both of the
foregoing junctions are detachable rather than permanent.
[0005] The present invention also is directed to a disposable
component of the fluid jet system including a disposable diaphragm
pump that has an inlet port connectable to a source of fluid to be
pumped and an outlet port in communication with a pressure
resistant delivery tube. The delivery tube is connectable, at a
distal end, to an instrument having one or more fine orifices for
creating the hair-thin fluid jet. The disposable diaphragm pump is
mountable to a reusable pumping chamber which will generate the
working force required to flex the diaphragm to fill and eject
fluid from a pumping chamber.
[0006] The present invention also involves a fluid jet system
including a high pressure pump having an inlet communicable with a
source of jetting fluid and a coiled burst resistant delivery tube
for conducting the pressurized stream. A jet nozzle may be
integrally or detachably connected, in leaktight fashion, with a
distal end of the delivery tube.
[0007] The present invention also involves a method of targeting a
fluid jet. A fluid jet system is provided including a variable
pressure pump, a source of fluid in communication with the pump, a
delivery tube in communication with an outlet of the pump and an
instrument in communication with the delivery tube having an
orifice for creating a fluid jet as the pumped fluid exits
therefrom. A visually observable "targeting" jet is created and
directed towards the target at a low pressure which does not damage
the target. The instrument is manipulated until the low pressure
fluid beam is pin-pointed onto the desired site. While maintaining
the jet on the target, the pressure of the fluid is increased. The
present method reduces the likelihood that areas surrounding the
target site will be damaged while aiming of the high pressure
jet.
[0008] Other aspects and features of the present invention will
become apparent from the following detailed description when taken
in connection with the accompanying drawings which disclose
multiple embodiments of the invention. It is to be understood that
the drawings are designed for the purpose of illustration only and
are not intended as a definition of the limits of the
invention.
DESCRIPTION OF THE DRAWINGS
[0009] The foregoing and other features and advantages of the
invention will be appreciated more fully from the following
drawings in which:
[0010] FIG. 1 is a schematic of a fluid jet cutting system
according to the present invention specifically configured for use
in surgical applications;
[0011] FIG. 2 is an illustration of the variable high pressure pump
illustrated in FIG. 1;
[0012] FIG. 3 is a sectional illustration of the disposable
diaphragm pump component of the variable high pressure pump;
and
[0013] FIG. 4 is a top view illustration of the latching mechanism
which secures the cartridge to the reusable pump housing.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0014] The present invention is a system for delivering a high
pressure stream of cutting medium, preferably a liquid, against a
target. Unlike a laser beam or a mechanical cutting instrument, the
fluid jet does not generate localized heat which can thermally
degrade regions surrounding the cutting site. The system allows
controlled, accurate and fast cutting. The diameter of the jet
stream and the pressure of the cutting medium may be selectively
varied depending upon the application. The components of the
cutting system may be integrally connected or, instead, detachable
allowing the interchange of, for example, cutting tools, pump
cartridges, etc. as required by the particular application or where
wear or failure requires replacement. A pressure resistant delivery
tube conducts the cutting fluid from the pump through an orifice
which creates the fluid jet. The delivery tube may be coiled to
enhance the maneuverability of the cutting stream. The fluid jet
may be a coherent beam or may assume other configurations, such as
an outwardly spreading spray, or a plurality of jet streams
converging on a focal point, depending upon the number, orientation
and shape of jet opening(s). The jet port may be provided in a
hand-held instrument, allowing a user to manually position the
fluid jet relative to the cutting site. The pump system may be
reusable or, preferably, includes a reusable component and a
limited use or disposable component which allows the portion of the
pump which directly contacts the cutting fluid to be separately
disposed of. The latter arrangement is particularly suitable where
a sanitary or sterile cutting fluid or cutting site is desirable.
The pressure and velocity of the fluid arc is selectively
controllable allowing the user to pin-point a visually observable
low pressure beam, having no significant cutting affect (from 10 to
1,000 p.s.i., and, preferably, about 200 p.s.i., depending on the
material which is subject to cutting) on the cutting site before
increasing the pressure of the fluid to within the cutting range
(from 1,000 to 50,000 p.s.i. and, preferably, from 5,000 to 30,000
p.s.i., again depending on the material being cut). A dye may be
provided in the fluid being jetted to enhance visualization.
Targeting the jet in this manner permits precise and controlled
cutting while reducing the incidence of unintentional damage of
material surrounding the cutting site.
[0015] The fluid jet cutting system is contemplated for use in a
wide variety of industrial applications including soft as well as
hard materials. Articles such as fabric, food, foam and plastics,
and specifically brittle or gummy materials which may stick to, or
be fractured or deformed by, mechanical cutting blades appear well
suited for fluid jet cutting. Sheets of baked goods, such as sticky
fig or granola bars, may be cut into individual portions prior to
packaging using the fluid jet system. Intricate shapes may be
formed using the cutting beam, particularly when the movement of
the jet is under computer control. Soft materials, such as foam or
plastics may be cut without distortion of the final product. The
fluid jet may be employed to core or drill materials and, for
purposes of this application, the term "fluid jet cutting" is
intended to be broadly construed and includes, without limitation,
use of a high pressure fluid beam to cut, drill, core, perforate,
strip, shape, delaminate and other forming and machining
operations. The jet nozzle may be configured for holding in the
hand of a user or for manipulation by machine control, such as an
X,Y,Z coordinate machine positioner. The latter embodiment further
suggests application of the jet cutting system on a commercial
scale.
[0016] The fluid jet cutting system is particularly indicated for
use in surgical procedures including, without limitation,
orthopedic arthroscopic procedures. Selective variation of the jet
stream pressure allows the surgeon to cut hard bone, soft bone,
cartilage and tissue, to strip away tissue exposing underlying
organs or vessels or, simply, to wash away blood and debris created
by the surgical procedure. The latter irrigating function ensures
good visibility of the operative site. Preferably, the jet is a
fine, coherent steam of sterile cutting solution, such as
physiological saline or, perhaps, a liquefied gas such as carbon
dioxide, which cuts or ablates the tissue or bone, and the stream
may then be used to pulverize the biological fragments into smaller
pieces. The emulsified debris may be flushed or evacuated from the
surgical site or the fragments can be removed using other
techniques. When used in medical procedures, the pressurized fluid
may contain vasoconstricting compounds to reduce bleeding, or
anesthetic compounds to reduce pain or other useful compounds may
be used to augment or facilitate a water jet medical procedure. The
jet wand may include a suction nozzle or a separate suction line
may be employed. Alternatively, positive pressure evacuation may be
employed to remove the effluent.
[0017] Selective variation of the jet pressure allows the surgeon
to target precisely a visible low pressure stream on the portion of
the bone or tissue to be excised and then to cut the bone or tissue
with the already pin-pointed jet simply by increasing the jet to a
higher, cutting pressure. A physiologically inert dye may be
dispersed in the sterile cutting fluid to enhance visualization of
the low pressure stream. Even when fully submersed in fluid, the
jet is ascertainable by the cavitation within the surrounding
solution. The hair-thin fluid beam, having a diameter in the range
of tenths of millimeters, preferably about 0.1 mm, permits the
surgeon to make fine controlled incisions without damaging
neighboring tissue, organs, vessels or nerves. A slender
hand-holdable wand or nozzle may be employed, facilitating use of
the fluid jet cutting system in surgical procedures which present
narrow spaces and complicated geometries.
[0018] A fluid jet cutting system for use where sterility of the
fluid jet is essential, such as in surgical applications, is
illustrated in FIG. 1. A pump console 22 contains control circuitry
and user information. Dials or buttons on the console allow the
user to vary the parameters of the system. The console includes a
reusable pump 26, in this case a piston pump, which is releasably
engageable, in leaktight fashion, with a disposable diaphragm pump
28. A source of sterile cutting fluid, such as a saline bag 30
suspended from an IV pole, is placed in communication with the
disposable pump via a flexible tube 32, shown disconnected in FIG.
1. The saline is forced under high pressure by the pump along a
delivery tube 36 to a hand-held surgical jet wand 40. Flow of the
cutting fluid is controlled by the surgeon through a foot switch
which communicates with the pump control circuitry. The fluid
delivery line 36 is formed of coiled stainless steel hypo tubing
which has sufficient burst strength to safely conduct the high
pressure fluid yet provides good maneuverability for the surgeon
due to the coiled configuration. The hypotube preferably is formed
of 14XH gauge (XH indicates extra heavy wall) type 316 or 304
stainless steel. The inner diameter of the tube shown is 0.036
inches and the outer diameter is 0.058 inch.
[0019] The hypotube may be formed by winding a straight length of
tube on a mandrel, preferably 0.63 inch in diameter, such that
adjacent coils are in contact. The ends of the hypotube remain
uncoiled, providing a straight length upon which to mount
hand-tightenable connectors or to integrally connect to the pump
outlet and the jet nozzle instrument where the components are not
desired to be detachable. Strain reliefs 37 may be mounted at the
ends of the hypotube to prevent the hypotube from kinking adjacent
to the connections to the pump outlet and jet nozzle instruments.
The delivery tube may be provided in its compacted configuration,
permitting the user to axially stretch the tube to the desired
length and flexibility. In a representative embodiment, ten (10)
feet of straight hypotube will yield approximately 4-6 feet of
coiled delivery tube. The as-used coils have an inner diameter of
0.85 inch and approximately 2.5 windings per inch. The delivery
tube preferably is rated for pressures in excess of 50,000
p.s.i.
[0020] A surgical jet instrument 40, preferably a wand that can be
held in the hand of a surgeon, includes a lumen in communication
with the delivery tube, that terminates in one or more fine axial
or transverse jet orifice(s) having a diameter in the tenths of
millimeters. Various configurations of the tip of the surgical jet
wand may be employed. Preferably, the tip is selectively moldable
allowing a surgeon to reshape or bend the jet tip into a
configuration, or at an angle, which facilitates positioning of the
nozzle relative to the surgical site. This feature is especially
attractive where the operative field is difficult to reach.
[0021] A deflector or catcher may be provided opposite the orifice
to transform the liquid jet into a harmless spray, preventing the
fluid arc from cutting deeper than is desired or from attacking
healthy tissue if the stream becomes misdirected. To ensure a small
instrument profile, the catcher may be slidable (in the axial mode)
or pivotable (in the transverse mode) from a slender configuration
employed during insertion of the instrument to an expanded
configuration at the surgical site. The slender configuration
facilitates use of the instrument in arthroscopy and other
procedures where small openings and narrow cannulas may be used to
enter the operative field. Alternatively, one or more jets may be
oriented to create a deflecting spray that accomplishes the same
aim as the catcher. A separate outlet may be provided on the jet
nozzle which is communicable at a proximal end (outside of the
patient) with a source of suction, such as the main hospital
supply, to allow aspiration of blood, surgical debris and the
cutting fluid. Alternatively, a separate suction line may be
employed. The separate outlet could also be an inlet for irrigation
fluid or the infusion of medicaments. Alternatively, the surgical
nozzle may be configured as the tip of a burst resistant catheter
such as is disclosed in U.S. Pat. No. 5,370,609, the contents of
which are incorporated herein by reference.
[0022] A quick connect adapter 42 may be provided at the end of the
fluid line, allowing the surgeon to switch quickly amongst varying
pre-shaped jet tips. In one embodiment of a hand tightenable
connector between the coiled delivery tube and the jet wand, the
coiled delivery tube includes a straight segment on one or both
ends which is permanently fitted with a ferrule. An O-ring is
slidably mounted over the tube end until it abuts the ferrule. The
protruding tip of the delivery tube is received by an inlet of the
jet wand or the outlet port of the pump. A thumb screw or other
fastening mechanism draws the ferrule and O-ring into seating
engagement in a stepped chamber having a reduced dimensioned recess
for the O-ring (slightly smaller than the O-ring) and a larger
chamber for the ferrule. The thumbscrew and ferrule may be
configured to provide compatible surfaces, facilitating insertion
of the ferrule into the stepped chamber as the thumbscrew and jet
wand or outlet port are threadably engaged. The ferrule bottoms out
against the floor of the chamber, deforming the O-ring a
predetermined amount, but no more, so that a high pressure seal is
affected between the first and second element without severely
distorting the gasket so that the O-ring can be easily removed when
the first and second bodies are separated.
[0023] The console includes a reusable working pump which is
segregated from the sterile saline and a disposable pumping portion
which acts directly on the saline, driving the sterile fluid at
high pressure through the flexible delivery line 36, out of the
surgical nozzle and into the operative site.
[0024] The two component pumping system works as follows. A
non-sterile working fluid is forced by a piston head, in the
reusable pump, against a flexible diaphragm in the disposable pump.
Flexure of the diaphragm in response to the pressure of the working
fluid reduces the volume in the disposable pumping chamber, forcing
the physiologic solution through an outflow port, the coiled fluid
line and, ultimately, the surgical jet wand. The diaphragm seats
against the mouth of the working cylinder as the piston is
retracted, drawing saline through an inflow port to refill the
disposable pump chamber. The pumping system cycles repeatedly
between filling and ejecting strokes, providing a nearly
continuous, pulsating, flow of high pressure fluid to the jet wand.
Check valves are provided in the inlet and outlet ports to ensure
the desired flow paths. Upon completion of the procedure, the
disposable diaphragm pump head is detached from the reusable piston
pump and discarded or resterilized for reuse. The piston pump,
which does not contact the sterile saline, may be reused with a
new, sterile disposable diaphragm pump.
[0025] A second flexible diaphragm (not shown) may be mounted on
the reusable pump at the cartridge interface. The second diaphragm
operates to prevent undesirable material from entering the pump
cylinder.
[0026] FIG. 2 provides a detail view of an assembled pump,
indicated generally by 24, including the reusable pump housing 26
and the disposable pump cartridge 28. Although a positive
displacement piston pump is illustrated as the reusable component,
other pumping mechanisms, such as an air intensifier, are
contemplated as would be apparent to the ordinary practitioner. The
reusable pump may be a pump disposed remote from the disposable
diaphragm pump and connected to the diaphragm pump by a high
pressure conduit. The reusable housing is preferably constructed of
type 304 or 316 stainless steel. A shaft 52, driven by a motor (not
shown), extends into a crank chamber 54. An eccentric crank 56 is
mounted on the shaft and is engaged to an elongate linkage rod 58.
Pin 62 connects the other end of the rod 58 to a cylindrical piston
rod 60. The piston 60 preferably is made of carbide, however, other
wear-resistant materials are suitable as would be apparent to those
skilled in the art. Bearings (not shown) may be provided at each
linkage connection to minimize friction between the respective
moving parts. The chamber 54 is filled with a lubricating oil which
also operates to reduce friction.
[0027] A cylindrical chamber 64, including a carbide containing
insert, receives the piston. In a preferred form of the invention,
the clearance between the cylindrical chamber 64 and the piston is
0.0002 inch. In a preferred embodiment, the diameter of the piston
is approximately 0.25 inch.
[0028] Rotation of the shaft 52 causes the eccentric crank to move
the linkage, reciprocating the piston within the chamber. The space
in the chamber unoccupied by the piston forms the working fluid
chamber. The piston reciprocates between a retracted position
defining the largest volume of the chamber and an extended position
where the unoccupied volume of the chamber is the smallest. The
distance between the extended position and the retracted position
is the piston stroke. In a preferred embodiment, the piston stroke
is about 0.25 inch.
[0029] An annular seal 70 isolates the working chamber from the
crank case. The seal is not subjected to the pressures of the
working fluid chamber. Consequently, a conventional oil seal may be
employed.
[0030] A pair of passages 72, 74 feed working fluid from a
reservoir into the piston chamber. The passages open just slightly
above the head of a fully retracted piston. Passages 78, 80 fluidly
connect the annular chamber to the exterior of the pump, allowing
water and air to flow between the annular chamber and the exterior
of the housing through valves 79 and 81, respectively.
[0031] The cartridge 28 is mounted into a compatable socket or
opening in the reusable pump housing and is securely retained there
by a locking lever 140 and latch 148, side views of which are shown
in FIGS. 1 and 2. Other arrangements for releasably engaging the
reusable and disposable pump heads may be employed as would be
apparent to those of skill in the art. For example, threadable
engagement of the reusable and disposable pump housing is
envisioned. A radially extending flange or shoulder 84 of the
pumping cartridge is engaged by the lever. One end of the locking
lever 140 is pivotally connected to the housing by a lever mount
144 and a pin 146. The pin allows the bar to pivot about the hinge
mount. A latch 148, which has an inverted L-shape, is pivotally
mounted by a pin 154 and a latch mount 152. FIG. 4 shows the
latching mechanism from above.
[0032] To lock the pump housings together, the locking lever is
swung over and against the shoulder of the cartridge. The latch is
then tilted to allow an extension 156 to engage the end of the
lever. A safety switch (not shown) is provided on the lever to
prevent the operation of the pump when the lever is in the unlocked
position. When unlocking the cartridge from the pump housing, the
latch is pivoted away from the locking bar and the extension 156 is
disengaged allowing removal of the cartridge.
[0033] The disposable pumping cartridge 28 is illustrated in FIG. 3
and includes a flexible, medical grade urethane diaphragm 86 which
is mounted on a lower surface 88 of the pumping cartridge. The
cartridge may be made of type 304 or 316 stainless or a plastic
such as a fiber filled acetal. An annular seal 90, preferably
integrally formed with the periphery of the diaphragm and formed of
the same urethane material, is seated in an annular channel 92. The
seal may be press fit into the channel 92. Alternatively, a "snap
fit" may be used whereby a ridge is provided which enables the seal
to snap into place. The seal and channel have different
cross-sectional shapes; in the illustrated embodiment the seal has
a circular cross-section while the channel has a square
cross-section. When the cartridge is mounted to the reusable pump
housing, the seal is compressed into a shape which conforms with
the annular channel. The size and cross sectional geometries for
the seal and the channel are such that when the cartridge is
latched to the pump housing stress is applied to the O-ring. When
the round O-ring cross section deforms into the rectangular cross
sectional shape of the annulus, the modulus of elasticity of the
seal increases to a value closer to the range of a hard plastic or
soft metal, allowing the compressed seal to withstand the elevated
pressures contemplated by the pumping system.
[0034] A passage extends from an inlet port communicable with a
source of saline to a variable sized pumping chamber defined by the
deformable diaphragm. A one way valve 98 controls the flow into the
chamber and prevents backflow into the sterile fluid source. The
check valve illustrated includes a ball 102 that is biased toward a
valve seat 104 by one end of a coil spring 106. The other end of
the spring rests on an annular lip 108 on the enlarged portion of
the housing defining the inlet passage. Other check valves may be
employed as would be apparent to those skilled in the art.
[0035] A passage 112 extends between an outlet communicable with
the high pressure delivery tube and the pumping chamber. A one way
valve 114 controls the flow of pumped fluid during the ejection
stroke and includes a ball 118 which is biased toward a valve seat
122 by one end of a coil spring 124. The other end of the spring
rests on a lip 126 on an enlarged portion defining the outlet
passage. Retracting the piston draws the diaphragm away from the
disposable housing, reducing the pressure in the pumping chamber.
The inlet check valve opens, allowing saline to fill the pumping
chamber. Extending the piston increases the pressure in the pumping
chamber, opening the outlet check valve and driving the pressurized
fluid out of the pump and into the delivery tube.
[0036] Preferably, the cartridge is installed in the compatible
socket in the reusable pump housing just prior to surgery. The
cartridge is mounted on the housing with the diaphragm draping into
the mouth of the working fluid chamber. The locking lever is
engaged to the latch, compressing the seal and securing the
reusable and disposable pump heads together. If air is present in
the working fluid chamber, such air should be removed prior to jet
cutting. A tube running from a saline bag may be connected to the
inlet of the disposable cartridge and the burst resistant, coiled
delivery tube may be attached to the outlet of the diaphragm
pump.
[0037] The assembled pump is inverted on an axis 180, as suggested
by arrow 182 (shown in FIGS. 1 and 2) and primed with working
fluid. Valve 79 controls the introduction of water while air is
allowed to escape through the passage 80 and valve 81. Slowly
moving the piston within the working fluid chamber facilitates
priming. Valve 81 is closed, after the chamber is filled, while
pressure continues to be applied to the passage 78. The primed pump
is ready for use.
[0038] The pump remains inverted during use to prevent air bubbles
from accumulating in the working fluid chamber, allowing the
bubbles to float into the annular reservoir when the piston is in
the fully retracted position. The piston, preferably, may cycle up
to 60 times a second. The pump speed may be selectively controlled
by the user via a control dial, a foot or hand switch (not shown),
allowing the pressure and cutting strength of the fluid jet to be
varied in real.
[0039] A representative procedure, in this case a meniscectomy,
employing the fluid jet cutting system will now be described. The
patient is anesthetized and a tourniquet is applied to the thigh of
the leg and set to a pressure of 280 mm Hg. The patient is prepped
and draped in a conventional manner. Saline is introduced to the
knee either through a superior medial portal using an inflow
cannula (three portal technique) or through a scope cannula placed
in the lateral portal at the joint line (two portal technique). The
saline exists the knee cavity out of medial portion at the joint
line. The pathology of the knee is visualized through a scope.
After bending the knee, valgus or varus stress is applied to
facilitate the approach to tight compartments. Suction may be
applied to clear tissue debris and to maintain a clear field of
view. The tip of the jet wand may be shaped to facilitate access
into the cutting location and to provide a proper cutting
orientation of the jet stream. The jet stream is introduced at a
low pressure while the cutting site is pinpointed. When the jet and
target coincide, the pressure of the stream is increased within the
cutting range to resect the tissue. The jet stream also breaks up
the resected tissue into smaller fragments. After completing the
surgery, the cutting instruments and scope are removed from the
portals and the knee is drained and wrapped.
[0040] It should be understood that the foregoing description of
the invention is intended merely to be illustrative thereof and
that other equivalents, embodiments and modifications of the
invention may be apparent to those skilled in the art.
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