CA2290530A1 - Cooling system for ultrasound device - Google Patents

Abstract

This invention is an ultrasound treatment system, and method for utilizing ultrasound to treat stenotic and occluded regions of blood vessels comprising an energy source (815), an ultrasound probe (200) for applying ultrasound energy to a treatment site that includes at least one transmission member (A), a passageway (245) communicating with the transmission member of the ultrasound probe (200), a fluid delivery system that includes a drive mechanism (36), a pusher block (34) for being driven by the drive mechanism, a syringe (50) for supplying fluid to the passageway (245) to cool the ultrasound probe (200), and a locking mechanism (150) for preventing the pusher block (34) from disengaging from the drive mechanism during operation.

Description

WO 98/52478 1'CT/US98/10089 This application claims priority under 35 U.S.C. ~~ 119(e) and 120 to copending prior Application Serial Nos. 60/047,022, filed May 19, 1997, and entitled s COOLING SYSTEM FOR ULTRASOUND DEVICE, and 08/858,247, filed May 19, 1997, and entitled ULTRASOUND TRANSMISSION APPARATUS AND
METHOD OF USING SAME.
BACKGROUND OF THE INVENTION
The invention relates generally to a cooling system for an ultrasound ~ o device, and, more particularly, to a cooling system that includes a pump for delivering fluid to medical devices that use ultrasound energy to treat locations within a human or other mammal.
The use of ultrasound devices for ablating or removing material obstructing blood vessels and the like in humans is known in the art. These devices use 1 s ultrasound energy, either alone or with other aspects of a treatment procedure, to facilitate the removal of material blocking blood vessels. One such device, an elongated ultrasound-transmitting probe that includes an ultrasound energy source, a horn, a transmission member, and a working piece or tip, has been used to ablate obstructions in blood vessels of humans or other mammals. One example of such a 2o device is disclosed in U.S. Patent No. 5,269,297, the contents of which is hereby incorporated by reference.
SUBSTITUTE SHEET ( rule 26 ) _ WO 98/52478 I'CT/US98/10089 Where ultrasound energy is required to be transmitted over long distances to remote locations within smaller blood vessels, such as the distal sections of coronary arteries, successful applications have been difficult to achieve.
This difficulty has been due, in part, to the difficulty in delivering sufficient ultrasound s energy to the tip of the probe without generating excessive heat, which could result in serious damage to the patient's blood vessels. This problem is described in the aforementioned reference, U.S. Patent No. 5,269,297.
Earlier efforts have addressed the heat loss problem by providing for a cooling arrangement in which the ultrasound transmitter is disposed within a catheter to which is flushed with a fluid. One such system is described in U.S. Patent No.
4,870,953, the contents of which is hereby incorporated by reference. However, this system has not been fully satisfactory in providing sufficient cooling with sufficient energy, without exhibiting additional drawbacks.
Aside from the heating problem, probes that are designed to reach is remote locations within a patient must be sized to allow for easy maneuverability and guidability so that the user may locate the tip of the probe at the treatment location quickly and accurately. To achieve improved maneuverability and guidability, probes may be sized to fit within smaller guide catheters. However, as the probe diminishes in size and cross-sectional area to fit within the smaller guiding catheters, the cross-2o sectional area that may be dedicated as a passageway for fluid to cool the transmission SUBSTITUTE SHEET ( rule 26 ) _ wire also decreases. Thus, there is a need for a cooling system that permits an ultrasonic probe to fit within a small guiding catheter.
Accordingly, it is desirable to provide an improved system for cooling an ultrasound probe which overcomes inadequacies of the prior art.
SUMMARY OF THE INVENTION
Generally speaking, in accordance with the invention, an ultrasound treatment system and method for utilizing ultrasound to treat stenotic and occluded regions of blood vessels, in particular the coronary arteries, are provided.
The ultrasound treatment system includes an energy source and an ultrasound probe that to includes at least one transmission member, such as transmission wire, rod or both, having a proximal and distal end. The transmission member can be covered in sheathing for containing cooling fluid pumped over the transmission member.
When energy is supplied from the energy source to the proximal end of the transmission member, the energy is transmitted to the distal end, which can include a tip, which in t 5 turn can be displaced in a longitudinal direction at the treatment site. A
guide catheter may also be provided such that the probe may be slidably disposed within the guide catheter. The transmission member can be partially contained within the sheathing that permits fluid to travel in a passageway between the sheathing and the transmission member. The guiding catheter can be connected to the outlet of a syringe by a conduit 2o so that fluid may be provided from the syringe by a syringe pump. The syringe pump can include a housing, a drive mechanism, including a motor, gearing and a lead SUBSTITUTE SHEET ( rule 26 ) WO 98/52478 1'CT/USO8/10089 screw, and a pusher block that rides on the lead screw for pushing the plunger of a syringe. The drive mechanism can drive the pusher block, which pushes the plunger of the syringe, which, in htrn, provides fluid via the syringe outlet to the probe.
The ultrasound treatment system may include a cooling system for s cooling the ultrasound treatment system. The control system may include: a way to detect whether a breakdown within the drive system has occurred or is impending; a way to monitor the upper and lower limits of force or pressure applied to the syringe to detect a malfunctioning syringe pump or fluid conduit system; a way to adjust the force applied to syringe plunger based on the force being measured at a plunger so as to to permit the regulation of fluid flow rate or pressure; and/or a releasable quick disconnect to connect the horn and the transducer to prevent undesirable axial displacement of the horn relative to the probe sheathing.
Accordingly, it is desirable to provide a cooling system for, among other applications, an ultrasonic device that overcomes the shortcomings of the prior art.
1 s It is another object of the invention to provide an improved device for treating thrombosis, stenosis and the like.
Another object of the invention is to provide an improved method for cooling an ultrasound device.
Yet another object of the invention is to provide an improved pump for 2o delivering fluid to a medical device.

SUBSTITUTE SHEET ( rule 26 ) Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification and drawings.
The invention accordingly comprises the several steps and the relation of one or more of such steps with respect to each of the others, and the apparatus s embodying features of construction, combinations of elements and arrangement of parts which are adapted to effect such steps, all as exemplified in the following detailed disclosure. The scope of the invention will be indicated in the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
For a fuller understanding of the invention, reference is had to the to following description, taken in connection with the accompanying drawings, in which:
FIG. 1 is a perspective view of an ultrasound transmission system, including a cooling system constructed in accordance with an embodiment of the invention;
FIG. 2 is a perspective view of a cooling system constructed in ~ s accordance with an embodiment of the invention;
FIG. 3 is a perspective view of a syringe pump type assembly constructed in accordance with an embodiment of the invention;
FIG. 4 is a plan view of a drive mechanism of a syringe pump assembly constructed in accordance with an embodiment of the invention;
2o FIG. 5 is a side view of an ultrasound transmission device constructed in accordance with an embodiment of the invention;
SUBSTITUTE SHEET ( rule 26 ) FIG. 6 is an enlarged side view of a portion of the distal end of a sheathed ultrasound transmission device constructed in accordance with an embodiment of the invention;
FIG. 7 is a cross-sectional view of a locking mechanism, engaged with a s syringe with plunger, constructed in accordance with an embodiment of the invention;
FIG. 8 is a side view of a locking mechanism constructed in accordance with an embodiment of the invention;
FIG. 9 is a side view of the locking mechanism depicted in FIG. 8;
FIG. 10 is a cross-sectional view taken along line 10-10, of the locking o mechanism of FIG. 8, constructed in accordance with an embodiment of the invention;
FIG. 11 is a cross-sectional view taken along line 11-11, of the locking mechanism of FIG. 9 constructed in accordance with an embodiment of the invention;
FIGS. 12A and 12B are cross-sectional views of a locking mechanism in disengaged and engaged positions, respectively, constructed in accordance with an t s embodiment of the invention;
FIGS. 13A and 13B are cross-sectional views of a locking mechanism in the disengaged and engaged positions, respectively, constructed in accordance with another embodiment of the invention;
FIGS. 14A and 14B are cross-sectional views of a locking mechanism in 2o the disengaged and engaged positions, respectively, constructed in accordance with another embodiment of the invention;

SUBSTITUTE SHEET ( rule 26 ) FIGS. 15A and 15B are cross-sectional views of a locking mechanism in the disengaged and engaged positions, respectively, constructed in accordance with another embodiment of the invention;
FIGS. 16A and 16B are cross-sectional views of a locking mechanism in s the disengaged and engaged positions, respectively, constructed in accordance with another embodiment of the invention;
FIG. 17 is a side view of a prior art transducer cable connector;
FIG. 18 is a side view of a transducer cable connector constructed in accordance with an embodiment of the invention;
to FIGS. 19A and 19B are cross-sectional views of a prior art half nut design; and FIG. 20 is a schematic of a electronic control system constructed in accordance with an embodiment of the invention.
is DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
It is desirable to provide an ultrasound probe capable of transmitting sufficient energy to the tip of the probe to cause cavitation at remote locations within blood vessels. Because reaching remote locations is made difficult by the tortuous vasculature required to be negotiated by the probe, it was determined that a probe 2o sized for a small guiding catheter would greatly improve the guidability, maneuverability and utility of the probe. Downsizing the diameter of the probe created SUBSTITUTE SHEET ( rule 26 ) cooling problems, however, because the available cross-sectional area within the probe dedicated for the passage of coolant tends to decrease as the entire cross-sectional area of the probe decreases.
It has also been determined that an effective way of ablating thrombus, s occlusions and the like, is to use an ultrasound probe to deliver ultrasound energy to a selected area within a patient's vasculature. It has also been determined that it is desirable to deliver ultrasound energy to a probe having a relatively large diameter proximal end. However, large diameters lead to undesirable stiffness and insertion problems. Accordingly, to accomplish the foregoing objectives, an ultrasound probe is o provided, which makes a rapid transition from a large diameter proximal horn section which receives the ultrasound energy from an ultrasound source, to relatively thin and flexible transmission medium, without a significant loss of transmission power, strength or guidability.
A non-limiting embodiment of an improved ultrasound probe is is illustrated generally as probe 200 in FIGS. l, 5 and 6, and in a copending application entitled ULTRASOUND TRANSMISSION APPARATUS AND METHOD OF
USING SAME under Application Serial No. 08/858,247, filed May 19, 1997, the contents of which are incorporated herein by reference.
Probe 200 is formed with a tapered horn 225, which includes a proximal 2o end 229 having a diameter Ai. When coupled to a source of ultrasound energy, proximal end 229 is preferably located at a displacement maximum relative to a SUBSTITUTE SHEET ( rule 26 ) standing ultrasound wave supported by the overall device. From proximal end 229, horn 225 tapers, in section A thereof, to a reduced diameter distal end 230, of diameter . A f at a transition zone B.
Proximal end 229 must be large enough to receive sufficient energy to s treat the thrombus, occlusions and the like. However, to provide optimal flexibility, it is desirable to reduce the diameter of distal portions of probe 200 as much as possible, without significant loss of energy, strength or guidability. Furthermore, the reduction in diameter is preferably accomplished in such a manner as to amplify the ultrasound vibrations.
Io Section C of probe 200 extends distally from transition zone B, and terminates in a mass or tip 250. Because ultrasound device 200 operates in the resonant frequency mode; i.e., it supports a standing wave when energized by ultrasound stimulation at proximal end 229, mass 250 is preferably located at a displacement maximum (anti-node).
is Section C may include multiple subsections having one or multiple wires. For example, section C may include a single transmission wire 240 that transitions at a transition zone D to parallel lengths of transmission media 260, each having a diameter smaller than that of wire 240. Transition zone D may include a joint or coupling 255 that couples several parallel lengths of transmission media, to a 2o single transmission wire. In that arrangement, it may be difficult for the mechanical strength of transition zone D to support maximum stress, and, as such, transition zone SUBSTITUTE SHEET { rule 26 ) D should be located at or near a displacement maximum (stress minimum).
However, in general, transition zone D may be located at a displacement node or anti-node or at any location therebetween.
To dissipate energy lost as heat, a probe in accordance with the s invention should be bathed with a coolant, such as water, saline or another fluid that can be introduced into a blood vessel. The coolant can be directed over and around the probe, for example, by incorporating a sheath 245 (FIG. 6) around some or all sections of the probe. Sheathing 245 may be affixed to the probe at one or more of the displacement nodes of the standing wave, but preferably at any of the displacement to nodes of section A, which are proximal transition section B. One example of such an arrangement is shown in FIG. 1. Additional sheathing may be incorporated for providing a passageway for a guidewire or other auxiliary tool which may serve to steer or position the device to its intended location. Sheathing 245 is advantageously formed of a high-strength, thin-walled, low-friction material, such as polyimide.
is It is understood that the techniques for assembling the sections of ultrasound device 200 are equally applicable to systems that promote or focus ultrasound energy to enhance the absorption of drugs, induce apoptosis in cells, and/or treat tissue, tumors, obstructions, and the Like, within and without the body, systems to be utilized in laproscopic surgery, liposuction, for ultrasonic scalpels, and to induce 2o tissue hypothermia for cancer radiation therapy, for example. Furthermore, drugs, such as streptokinase, urokinase, and platelet inhibitors, contrast media, and other SUBSTITUTE SHEET ( rule 26 ) fluids whose function or efficacy would be enhanced by ultrasound or that would enhance the application of ultrasound at the treatment site, may be infused within the coolant fluid for cooling the ultrasound probe or delivered through a separate passageway within or without the ultrasound probe to the treatment site.
s Referring to FIG. 5, a probe with a constant diameter section as part of the horn section, is shown generally as probe 200. Horn 225, having a tapered section 226 and a first constant diameter section 227, is constructed to be coupled to an ultrasound energy source. Refernng to FIG. 1, ultrasound energy is provided by a controller 815. Energy is supplied by a power source 246 via a coaxial cable 247 to a to quick disconnect 248, which connects coaxial cable 247 to a transducer 249.
Transducer 249 is intimately connected to horn 225. Probe 200 also includes transmission member 240 coupled to horn 225 at the distal end of transition zone B
(FIG. 5), and tip 250 coupled to the distal end of transmission member 240.
Ultrasound energy sources disclosed in U.S. Patent No. 5,269,297, and in a copending i s application entitled FEEDBACK CONTROL SYSTEM FOR ULTRASOUND
PROBE under Application Serial No. , the contents of which are incorporated by reference, are suitable.
Tip 250 is coupled to three fine wires 260 by use of three openings in the proximal end of tip 250. In a preferred embodiment, the three openings in coupling 20 255 and in tip 250 are spaced so as to form an equilateral triangle, concentric with the central axes of coupling 255 and tip 250. Tip 250 may also be provided with an SUBSTITUTE SHEET ( rule 2b ) opening for a guidewirc, and a guidewire tube may be installed in the opening and extended proximally (and distally) from the ends thereof. Fine wires 260 may be separately sheathed with a fine wire sheathing 261 sheathing that may extend between tip 250 and coupling joint 255. A gap 260' is advantageously provided between the s distal end of fine wine sheathing 261 and the proximal end of tip 250. The gap should exceed any expansion in the length of the sheathing that can occur during probe operation. Wire 240 may also be sheathed and that sheathing may be connected to the separate sheathing 261 of wires 260 and may extend proximally to a coolant port through which coolant may be injected to bathe all or part of portions 226, 227, 240 to and 260.
One known way of delivering a coolant to ultrasound probe 200 is to use a syringe pump-type device, such as those typically used to infuse medication into a patient. Such pumps operate at low pressures, with a maximum plunger force in the range of 6-12 psi. A syringe pump-type device generally includes a motor, a pusher t s block, a lead screw and a syringe. The pusher block generally includes a half nut, which is located below the lead screw and is held against the lead screw by a compression spring. When the motor causes the lead screw to rotate, the half nut rides on the lead screw threads, thereby propelling the pusher block against the syringe plunger, which pushes fluid into an infusion line.
2o Because the cross-section tolerances for fluid flow are tighter in a probe sized to fit within a narrow guiding catheter (such as a 7 French guiding catheter), and SUBSTITUTE SHEET ( rule 26 ) a constant flow rate is preferred to cool the transmission wire, fluid must be delivered at a high pressure, well above 20 psi, to force sufficient fluid to flow through the narrow passageway.
This problem of a reduced coolant passage cross section can be s addressed by providing a high pressure pump for delivering fluid to cool the probe, as conventional low pressure pumps are not capable of delivering the flow rates required to cool an ultrasound probe sized to be contained within a small guiding catheter.
Conventional syringe pumps, however, are not. always fully adequate for delivering higher pressures to the coolant system. For example, at times, the pusher block i o assembly that drives the plunger of the syringe to supply coolant to the probe will fail to track on the lead screw.
As noted above, conventional syringe pumps operate at low pressures and utilize a pusher block assembly with a half nut design, which biases the half nut against the lead screw with a compression spring. Such half nut designs are not i 5 suitable to operate under the high pressures required by ultrasonic probes having reduced coolant passage cross-sections.
An example of a prior art half nut design is shown in cross-section in FIGS. 19A and 19B. A pusher block 334 includes a housing 390, which houses a half nut 305 and plunger 308. Half nut 305 is located below and substantially perpendicular 2o to a lead screw 310, and is biased against screw 310 by a compression spring 320. The spring force of spring 320 is chosen to be sufficient to maintain half nut 305 pressed SUBSTITUTE SHEET ( rule 26 ) against lead screw 310. Pusher block 334 also includes a push button 360, which is connected to and extends from plunger 308, through a bore 391 in housing 390.
Push button 360 includes a shaft 361 and a cap 362.
Pusher block 334 may be positioned along lead screw 310 by depressing push button 360 so that plunger 308 releases half nut 305 from lead screw 310 by acting against spring 320. In this condition, pusher block 334 is easily moved along lead screw 310.
When lead screw 310 is caused to rotate by a driving mechanism (not shown), half nut 305 moves along the thread of lead screw 310 until pusher block 334 o encounters a syringe (not shown), positioned in line with pusher block 334.
At this time, the exterior edges of half nut 305 exert force on the inside of pusher block 334, and thereby exert force against the syringe. When the force exerted by pusher block 334 becomes greater than the countering force of the syringe, pusher block 334 begins to drive the syringe plunger and, thereby "push" fluid from the syringe.
Thus, conventional pusher blocks included a half nut designed to float against a lead screw. When lead screw 310 begins turning, it exerts a normal force toward the half nut which acts to push half nut 305 off the lead screw threads. The half nut "floats" so that the normal force may be reduced by shifting sideways, thereby reducing the total force at a normal angle. Floating is effective when the half nut faces light loads. However, when greater pressure is applied to the half nut, occasional slippage of the half nut on the lead screw can occur. One way to prevent slippage is to SUBSTITUTE SHEET ( rule 26 ) increase the spring force constant k of compression spring 320. However, as spring force is increased, it may become too difficult for an operator to depress push button 360, to release the half nut 305 in order to position pusher block 334 along lead screw 310.
It was also determined that the spring force was not sufficient to fully engage all the threads on the half nut with lead screw 310. As a result, when the pump is running, half nut 305 can shift downward, due to the lead screw normal force, and continue working with only the top edges of half nut 305 engaged with lead screw 310. This arrangement can cause excessive wear of the topmost corner threads of half o nut 305, and results in poor force transmission from lead screw 310 to half nut 305.
Thus, during operation, the normal force on the threading of the half nut can cause the half nut to jump or slip the lead screw threads. When this occurs, the pusher block does not move forward at a constant rate, thereby causing a fluctuation in the flow rate of the fluid, and putting a patient who relies on a constant flow rate to Is cool the probe at risk.
One solution investigated was increasing the strength of the spring to compensate for the higher forces at the threading. However, increasing the pressure of the spring made it more difficult for the user to manually position the pusher block.
To provide an improved pusher block assembly, it was determined that a 2o second biasing force would advantageously ensure that the half nut was locked to the lead screw so that the pusher block reliably tracked over the lead screw, and thereby SUBSTITUTE SHEET ( rule 26 ) WO 98/52478 1'CT/1JS98/10089 provided a constant fluid flow rate to cool the ultrasound probe. Multiple, non-limiting examples of embodiments of this invention are described below.
Referring to FIGS. 1 and 2, a cooling system, generally indicated at 500, and constructed in accordance with one prefen-ed embodiment of the invention, is s disclosed, in which similar elements are assigned the same reference numerals.
Cooling system 500 includes a housing 32, a controller 815, a syringe pump 30 for delivering fluid, an ultrasound probe 200 for receiving the fluid, and a fluid conduit 98 for coupling pump 30 to probe 200.
When probe 200 is activated, cooling system S00 provides coolant to io ultrasound probe 200 when controller 815 signals syringe pump 30 to pump fluid from a syringe 50. Upon activating syringe pump 30, fluid is forced via a syringe valve 99 through fluid conduit 98 to a catheter valve 96 and finally to probe 200, where the fluid is passed between sheathing 245 and at least part of transmission wire sections 227, 240 and/or 260. Given the speed with which ultrasound probe 200 can heat in the ~ s absence of coolant to bathe the transmission wire, it is extremely important to ensure that fluid flows at a constant rate over the transmission wire so that heat dissipated from transmission wire sections 227, 240 and 260 is transferred to the flowing fluid, and thereby conducted away from the transmission wire sections. In the absence of a coolant fluid, the transmission wire sections of probe 200 can quickly heat to a level 2o that could cause serious injury to a patient.

SUBSTITUTE SHEET ( rule 26 ) As is shown in FIGS. 1 and 2, housing 32 includes a display panel 79, a back panel 140, a back casing 141, a front casing 142, all of which can be formed of . plastic material and joined, and a top casing 83, which is hinged to back panel 140 by a casing hinge 78. Top casing 83 may be rotated about casing hinge 78 to expose s syringe pump 30. Display panel 79 contains the operator control panel (not shown).
Back panel 140 includes foot pedal plug 145 for receiving a foot pedal cable (not shown), a service port 146, and a power plug 147, each positioned at easily accessible locations within back panel 140.
Referring to FIGS. 2 and 3, syringe pump 30 is contained within housing Io 32, and includes a support 90 disposed within and supported by housing 32.
As is shown in FIG. 3, support 90 includes a top platform 91, a bottom platform 92, supported within housing 32, and a first upright 76 and a second upright 77, coupling bottom platform 92 and top platform 91.
As is shown most clearly in FIG. 7, syringe 50 of pump 30 includes a is barrel 52, having a distal end 204 with an outlet 55, and a proximal end 205, having a flange 53. Syringe 50 also includes a plunger 54, having a proximal end 207, which has a proximal flange 56, and a distal end 206, which has a distal flange 206, sized to fit within barrel 52.
Turning back to FIGS. 2 and 3, a cradle 46 of pump 30 is supported by 2o top platform 91, and is divided into an upper portion 47 and a lower portion 48, which are joined by a hinge 49, and are releasably connected by a lockdown mechanism 51.

SUBSTITUTE SHEET ( rule 26 ) WO 98/52478 PC'r/US98/10089 Upper portion 47 can be pivoted about hinge 49 to permit barrel 52 of syringe SO to be positioned within lower portion 48 of cradle 46 so that bawel 52 can be properly aligned with pusher block 34. Syringe 50 is positioned in cradle 46 such that an upper surface of plunger flange 56 faces pusher block 34. When upper portion 47 of cradle s 46 is closed over barrel 52, barrel flange 53 is prevented, by cradle 46, from moving in the same direction as pusher block 34. Accordingly, when properly positioned, barrel flange 53 is not disposed within cradle 46. Rather an underside 53a of flange contacts lockdown mechanism 51 so as to prevent barrel 50 from moving in the same direction as pusher block 34, when pusher block 34 is driven to move in a fluid-to dispensing direction F along a lead screw 44 described below with reference to FIG. 4.
Referring to FIG. 4, syringe pump 30, mounted within housing 32, also includes a drive mechanism 36, which includes a motor 40 having a shaft 41, coupled to a reducer 42, which turns a lead screw 44 and impels pusher block 34 along lead screw 44. Pusher block 34 is guided by a first rail 80 and a second rail 81.
First rail 80 1s and second rail 81 are mounted at each end to first upright 76 and second upright 77.
The speed of lead screw 44 is monitored by an encoder 39, mounted on upright 76, which feeds back to controller 815.
Lead screw 44 is axially supported by bearings (not shown), which in turn are supported in first upright 76 and second upright 77. Lead screw 44 is 2o threaded, and, in a preferred embodiment is formed of steel and configured as LTNF
3/8" x 24. Reducer 42, which operatively couples lead screw 44 to motor 40 may SUBSTITUTE SHEET ( rule 26 ) include appropriately sized gears to reduce the speed of motor shaft 41 to an appropriate pump or lead screw speed. In a preferred embodiment, reducer 42 includes a combination of timing belts and pulleys that translates the motion from motor shaft 41 to lead screw 44 while reducing the rate of rotation by a ratio of 12.6:1.
While the s gear reduction reduces the speed of the lead screw, it concomitantly increases the torque available to syringe pump 30 by the same 12.6:1 ratio. It is understood that those skilled in the art can devise other drive mechanisms for driving lead screw 44 at appropriate speeds and torques.
Turning now to FIGS. 8 to 11, pusher block 34 includes a housing 66 io and a wing 68 attached thereto. Wing 68 includes a T-bar 73 and a pusher block biasing assembly 62. T-bar 73 is advantageously formed of plastic material which helps to reduce vibration within pusher block 34 during operation. Housing 66 is positioned substantially perpendicularly to lead screw 44, and is advantageously formed of a strong, light-weight material, such as aluminum. As depicted in cross Is section in FIG. 10, housing 66 is generally cylindrical in shape at its upper one-third, flares to form a skirt 95 on either side of at the middle one-third, which reduces in cross-sectional diameter to accommodate top platform 91 (FIG. 3), and flares under top platform 91 to form a rectangular block shaped base 85. Housing 66 is bored to form plug bore 87 which accommodates pusher block biasing assembly 62.
Referring 2o to FIG. 11, biasing assembly 62 is held within housing 66 by lower plug 119. The SUBSTITUTE SHEET ( rule 26 ) _ upper third of housing G6 has two opposing slots 67 that permit T-bar 73 to be supported thereon.
Wing 68 is supported on T-bar 73, which in turn is supported on slots 67 of housing 66, and includes a first ann 71 on one side, a second arm 72 on the other side, a wing catch 74, and pins 75. First arm 71 is integrally connected with second arm 72, and wing catch 74. Wing catch 74 includes a lower surface 74a and a notch 74b. Wing 68 may be formed of metal or a composite material, but preferably is advantageously formed of aluminum.
Base 85 of housing 66 has a first bore 86 at one side thereof, a second o bore 88 at the other side, and a central bore 89 therebetween, positioned within housing 66 an in the same plane to provide stability to pusher block 34. As such, bores 86, 88 and 89 are preferably spaced apart from one another along the same plane.
Turning to FIG. 8, disposed within bores 86 and 88 are bushings 86a and 88a, preferably formed of Teflon~, to minimize wear to base 85. Bore 86 is further t s provided with a tubing 86b, preferably formed of bronze, to provide stability to pusher block 34 as it moves along lead screw 44. First bore 86 and second bore 88 are dimensioned to accommodate bushing 86a, tubing 86b and first rail 80, and bushing 88a and second rail 81, respectively. Central bore 89 is sized to accommodate lead screw 44. First rail 80 and second rail 81 are provided to ensure that pusher block 34 2o is aligned with lead screw 44 and to counter torsional forces created when pusher SUBSTITUTE SHEET ( rule 26 ) WO 98/52478 PCT/t3S98/10089 block 34 is driven against plunger 54. In this way, pusher block 34 is made to smoothly actuate plunger 54 of syringe 50.
As is shown most clearly in FIGS. 8 and 10, housing 66 provides the structure within which pusher block biasing assembly 62 is disposed, and provides the s structure upon which wing 68 travels. Housing 66 also includes an antisiphon catch 65 and a pressure plate 35, which are integrally connected, preferably formed of a plastic, and mounted on housing 66. Antisiphon catch 65 is V-shaped and is connected to housing 66 at skirt 95 above central bore 89. Antisiphon catch 65 has a notch configured to accommodate flange 56. Wingcatch notch 74b is similarly configured to to accommodate flange 56 and opposes antisiphon catch notch 64. Thus, when flange 56 is positioned within antisiphon catch 65 and wingcatch notch 74b prior to the time when coolant is driven from syringe 50, it is prevented from moving independently of pusher block 34. Pressure plate 35 is mounted on housing 66 so that when flange 56 is positioned within catch 65, pressure plate 35 pushes directly against syringe plunger ~s flange 56 ~o force fluid from a syringe barrel 52.
As is shown in FIGS. 7, 8 and 11, a force sensor 70, advantageously approximately 0.03 inches thick, can be formed of several layers of traces placed on top of a conductive rubber layer, and face of pressure plate 35. In a preferred embodiment, force sensor 70 includes a sensor button 70a, which is mounted on zo pressure plate 35 such that when plunger flange 56 is engaged with antisiphon catch 65 and wing catch notch 74b and pusher block 34 is driven by motor 40, the force SUBSTITUTE SHEET ( rule 26 ) applied to plunger flange 56 presses pushbutton 70 which compresses the layers of force sensor 70. Force sensor 70 feeds an output signal to controller 815, which thereby monitors the pressure applied to plunger flange 56.
Referring to FIGS. 10 and 11, wing 68 is formed to overlap T-bar 73, which is shaped in the form of a "T" when viewed from the plan view of housing 66.
T-bar 73 includes a top portion 132, which is attached at its outer edges to wing 68 at first arm 71 and second arm 72, and a stem 133, which extends through slots 67 into plug bore 87 of housing 66, and rides therein. T-bar 73 is preferably bolted to arms 71 and 72. An upper plug 119 is formed in the shape of a cylinder, sized to fit within to plug bore 87, and machined to fit snugly with stem 133. Stem 133 is bored perpendicularly to its length dimension, in the direction of plug bore 87, to accept a bolt 134, which attaches the lower end of a plunger spring 112 to stem 133, and in turn to upper plug 119. Upper plug 119 is preferably machined from bronze, and functions to help center wing 68 in plug bore 87 and to guide wing 68 when wing 68 is pulled t s upwardly along slots 67. Absent such a force pulling upwards, plunger spring 112 biases wing 68 against the lower point of travel in slots 67.
As is shown in FIGS. 10 and 11, pusher block biasing assembly 62 of pusher block 34 includes push button 60, a plunger 110, having a plunger upper end 113 and a plunge actuator 114, a compression spring 115, and a locking mechanism 20 100. Plunger 110 preferably is formed of bronze. Upper end 113 is connected to push button 60, and is bored to accept an upper end of plunger spring 112. Push button 60 is SUBSTITUTE SHEET ( rule 26 ) preferably formed of aluminum, and has a shaft 63, which is bored to permit the insertion of plunger spring 112. Thus, plunger spring 112 occupies the space defined by stem 133, plunger 110, and pushbutton 60. Plunger actuating end 114 is machined to accept compression spring 115, which is seated between lower plug 119 and plunger actuator 114 within housing 66.
In a preferred embodiment of the invention, shown in FIGS. 10 and 11, plunger 110 has a bore 125, having an upper edge 126 and a lower edge 127, and an upper portion 128 and a lower portion 129. Bore 125 is sized such that lead screw 44 can be positioned within either- upper portion 128 or lower portion 129. Lower edge 0 127 of bore 125 is threaded so that it can engage lead screw 44.
In a first position, compression spring 115 biases lower edge 127 against lead screw 44. In a second position, when plunger 110 is actuated by a downward force applied to pushbutton 60, lower end 114 counters the force of compression spring 115, the threading of lower edge 127 is disengaged from the threading of lead ~ 5 screw 44, and plunger 110 moves downwardly, whereby lead screw 44 is accommodated by upper portion 128 of bore 125. In this manner, pusher block 34 can be positioned along the length of lead screw 44.
The operation of coolant system 500 will now be explained with reference to FIGS. 2 and 7. First, when pusher block 34 is disengaged from lead 2o screw 44, the user aligns syringe 50 with pusher block 34 by positioning plunger SUBSTITUTE SHEET ( rule 26 ) flange 56 within antisiphon catch 65. Upon positioning plunger flange 56 in antisiphon catch 65, the user permits pusher block 34 to engage lead screw 44.
To overcome the slippage problem identified with the conventional half nut design, it was determined that an additional biasing force was required to "lock"
s lead screw 44 to pusher block 34. An embodiment of the invention, shown at FIGS.
16A and 16B, was designed employing some of the components of the conventional half nut design. Rather than relying only on compression spring 115 to bias a half nut 120 against lead screw 44, a locking mechanism 150 was added in accordance with one embodiment of the invention.
to Locking mechanism 150 is preferably made of aluminum, and formed with a pawl 103, having a tongue 101, an actuating portion 102, and a pawl spring 118. Half nut 120 is threaded to mesh with lead screw 44, and notched at a notch 122 to accept tongue 101. Pawl spring 118 is connected to housing 66 so as to hinge pawl 103 at a location above half nut 120 on housing 66, and is located between plunger ~5 110 and half nut 120. As is shown in FIG. 16A, which depicts locking mechanism 150 in an engaged position, locking mechanism I50 is spring-biased such that tongue 101 rests in notch 122 of half nut 120.
To load cradle 46 with syringe 50, the operator lifts wing 68 in a direction depicted by an arrow X of FIG. 16B, while pressing down on pushbutton 60 2o in a direction indicated by an arrow Y of FIG. 16A. Pusher block 34 is designed to require the operator to press pushbutton 60 with his or her thumb, while raising wing SUBSTITUTE SHEET ( rule 26 ) 68 with two fingers placed on the underside 69 of wing 68. Wing 68 is permitted to travel in slot 67 of pusher block housing 66 until wing 68 reaches the limit of its upper travel movement.
At a first or locked position depicted in FiG. 16A, half nut 120 contacts s the threading of lead screw 44, and wing 68 is biased in its down position by plunger spring 112. At a second or released position depicted in FIG. 16B, wing 68 is at the upward limit of its travel and push button 60 is depressed as to force plunger 110 into half nut 120, thereby releasing half nut 120 from lead screw 44.
In this embodiment, when the user presses down on pushbutton 60 in a to direction shown as arrow Y, plunger 110 is forced downward in a direction substantially normal to lead screw 44. The downward force applied to pushbutton 60 is translated to half nut plunger 110, which moves in the downward direction toward halfnut 120. Upon moving a selected distance, actuator 114 of plunger 110 contacts actuating portion 102 of pawl 103, thereby pivoting pawl 103 in a counterclockwise ~5 direction shown by an arrow Z, and disengaging tongue 101 from half nut notch 122.
In this manner, plunger 110 is permitted to contact half nut 120 and transmit the force exerted by the user on pushbutton 60 to compress compression spring 11 S, thereby disengaging half nut 120 from lead screw 44. At this position, the user may position pusher block 34 on lead screw 44 so that syringe 50 may be readied for use.
2o In this embodiment, the release of pawl 103 requires only pressing down on pushbutton 60. However, in this position, the distance W measured from a bottom SUBSTITUTE SHEET ( rule 26 ) surface 74a of wing catch 74 to a top surface 65a of antisiphon catch 65 is not large enough to permit syringe plunger flange 56 to be positioned between wing catch and antisiphon catch 65. Thus, to position plunger flange 56 of syringe 50 in antisiphon catch 65, the user pulls up on wing 68 in a direction shown as arrow X in s FIG. 16B. In this way, wing 68 travels upwardly in slots 67 acting against plunger spring I 12 when upper plug 11 J, which is connected to wing 68, bottoms out spring 112, the distance W' is large enough to accommodate spring flange 56. The operator then places syringe barrel 52 in cradle 46, slides pusher block 34 up to syringe plunger 54, and positions plunger flange 56 within antisiphon catch 65. Once plunger-flange to 56 is positioned correctly within antisiphon catch 65, the user may release wing 68 to permit wing catch 74 to lock plunger flange 56 against pressure plate 35.
Plunger 54 is held in this position by the compressive force of plunger spring 112.
When the user releases the pressure applied to pushbutton 60, halfnut 120 is biased by compression spring 115 against lead screw 44 and pawl 103 pivots ~ s under the force of pawl spring I 18 in a clockwise direction opposite to arrow Z, such that tongue 101 engages notch 122, thereby locking half nut 120 against lead screw 44.
In this position, the user is no longer permitted to move pusher block 34 in the direction of travel along lead screw 44.
In this embodiment of the invention, the k factor of compression spring 20 115 is advantageously set higher than that of plunger spring 112 to cause the user to lift up on wing 68 prior to depressing pushbutton 60. That is, when the user pulls up SUBSTITUTE SHEET ( rule 26 ) on wing 68 while pressing pushbutton 60, the user will normally overcome the lighter spring load of plunger spring 112 first, and then raises wing 68 prior to disengaging locknut 120 from lead screw 44. Thus, in a preferred embodiment of the invention, locking mechanism 150 can only be released if the user simultaneously presses down on pushbutton 60 while lifting wings 68.
In a second embodiment of the invention, depicted at FIGS. 10 and 11, where similar parts are numbered similarly, the structure labeled half nut 120 in FIGS.
16A and 16B is integral with plunger 110, and plunger 110 is maintained in its first position by a locking mechanism 100. This embodiment permits locking mechanism to I 00 to be placed anywhere along the full length of plunger 110. As is shown in FIGS.
11, 12A and 12B, locking mechanism 100 includes a ball bearing 108, which is positioned within a channel 107 in housing 66 and a recess 109 in plunger 110.
The operation of this embodiment will be described with reference to FIGS. 12A and 12B. Pusher block 34 is in a first position where locking mechanism ~s 100 is engaged, thereby maintaining plunger thread 128 biased against lead screw 44.
In this position, ball bearing 108 prevents plunger 110 from moving in a downward direction by its position within recess 109 of plunger 110. In this position, ball bearing 108 is retained by middle portion 73, which prevents ball bearing 108 from moving in a direction shown by an arrow V. As such, when pump syringe 30 is 2o actuated and delivers pressures of up to 85 psi, for example, lead screw 44 is locked to SUBSTITUTE SHEET ( rule 2f ) plunger thread 127 causing pusher block 34 to track reliably on lead screw 44 and deliver a constant flow rate of fluid to cool ultrasound probe 200.
When the user pulls up on first arm 71 and second arm 72 (FIG. 10), in a direction shown by an arrow X in FIG. 12B, wing 68 moves in an upwardly direction s over slots 67 and compresses plunger spring 112. When middle portion 73 reaches a position wherein it no longer retains ball bearing 108, upon depressing pushbutton 60, plunger 110 is able to move in the downward direction because ball bearing 108 no longer prevents the movement of plunger 110 as ball bearing 108 moves into channel 107 under the force of the initial downward movement of plunger 110. When plunger t o 110 is fully depressed, plunger 110 acts against and overcomes compression spring 115, thereby disengaging thread 127 from lead screw 44. Ball bearing 108 is prevented from falling out of housing G6 by staking the outer edges of channel 107 or by counter-boring channel 10? from the interior side of housing 66, such that the inner diameter of channel 107 is slightly greater than the diameter of ball bearing 108 and 1 s the outer diameter of channel 107 is slightly less than the diameter of ball bearing 108.
Referring to FIGS. 14A and 14B, another embodiment of a locking mechanism, shown generally as 450, is shown. FIG. 14A depicts locking mechanism 450 in its locked position, where plunger 110 is locked against lead screw 44, and FIG.
14B depicts locking mechanism 450 in its unlocked position, where plunger 110 is 2o permitted to act against spring 115. Locking mechanism 450 includes a triangle-shaped bar 151, a notch 152, and a spring-loaded hinge 153. Bar 151 can be located SUBSTITUTE SHEET ( rule 26 ) anywhere along the length of plunger 110. Plunger 110 includes notch 152, which is formed by tapering the cross-sectional diameter of plunger 110, such that bar 151 may be received therein. Hinge 153 is connected to housing 66 and to one end of bar 151, and is spring-loaded such that bar 151 is biased away from plunger 110.
s In the locked position depicted in FIG. 14A, middle portion 73 prevents bar 151 from rotating in a clockwise direction, shown by an arrow T, by its position abutting an outer edge 151a of bar 151. As wing 68 is lifted by the user, and middle portion 73 no longer abuts outer edge 1 S 1 a to retain bar 151, bar 151 rotates away from plunger 110 in a direction shown by arrow T under the force of spring-loaded io hinge 153 to a position shown in FIG. 14B. In this manner, plunger 110 is no longer prevented from moving in the direction of arrow X when the user presses pushbutton 60. Thus, this embodiment provides a novel structure that serves to lock pressure block 34 against lead screw 44 even under high pressure loads, and permits the user to easily disengage pressure block 34 from lead screw 44 to quickly locate pusher block is 34 at a selected position.
Referring to FIGS. 15A and 15B, a locking mechanism 550, constructed in accordance with another embodiment of the invention, is shown. FIG. 15A
depicts locking mechanism 550 in a locked position, and FIG. 15B shows locking mechanism S50 in an unlocked position. Locking mechanism 550 includes a latch 161, a notch 20 162, and a spring-loaded hinge 163. Locking mechanism 550 is similar to locking mechanism 450 depicted in FIGS. 14A and 14B, except that bar 151 of locking SUBSTITUTE SHEET ( rule 26 ) mechanism 450 is rotated I80 degrees to form latch 161. As a result, spring-loaded hinge 163 biases latch I51 in a direction shown by an arrow S. Latch 161 is prevented from moving in the direction of arrow S by middle portion 73, which abuts an outer edge 161 a of latch 161. As wing 68 is lifted by the user, middle portion 73 is moved s from its position depicted in FIG. 15A to the position depicted in 15B, where middle portion 73 no longer retains latch 161. As such, latch 161 rotates away from plunger 110 in the direction indicated by arrow S under the force of spring-loaded hinge 153, thereby permitting the user to press pushbutton 60 to disengage plunger thread from lead screw 44.
to FIGS. 13A and 13B show a locking mechanism 650, constructed in accordance with another embodiment of the invention. FIG. 13A depicts locking mechanism 650 in a locked position, and FIG. 13B shows locking mechanism 650 in an unlocked position. Locking mechanism 650 includes a plurality of ball bearings 644, an upper plug 619 formed with a wide diameter portion 620, a narrowed portion is 642 and a retaining portion 621, and a channel 643 which extends from housing 66 through plunger 110. Upper plug 619 is preferably formed of bronze, and is sized to fit within central bore 89 of housing 66. Upper plug 619 is attached to stem 133 of T-bar 73 such that when wing 68 is lifted by the user in a direction shown by an arrow X, upper plug 6I9 moves upward. As is shown in FIG. 13B, when narrowed portion 20 of upper plug 619 is moved to a location adjacent ball bearings 644, ball bearings 644 move toward narrowed portion 642, and into the space vacated by the wider diameter SUBSTITUTE SHEET ( rule 26 ) portion 620 of upper plug 619. In this way, locking mechanism 650 is released, thereby permitting the user to disengage plunger thread 127 from lead screw 44 by _ pressing pushbutton 60. In this condition, ball bearings 644 are retained between the outer surface of narrowed portion 642 and that part of channel 643 formed within s plunger 110. Thus, ball bearings 644 are permitted to ride on the inner surface 623 of housing 66 when the user depresses pushbutton 60.
This embodiment differs from the other embodiments, as locking mechanism 650 is entirely contained within housing 66. That is, ball bearings 644 are retained, or permitted to be moved, by the interior movements of wing 68 rather than by the release of locking mechanism 650 by the upward travel of T-bar 73.
Reference is next made to FIG. 20, which shows a schematic diagram of an electronic control system, indicated generally as 800, for controlling cooling system 500 of the invention. Electronic control system 800 monitors the functioning of syringe pump 30, and is generally controlled by a control board 810, which is in turn is coupled to controller 815. As is shown in FIG. 20, a pulse generator 870 is controlled by controller 815 through control board 810. Controller 815 instructs pulse generator 870, by signal 811, to provide electrical pulses at a predetermined frequency of a predetermined length. These pulses are sent to an output buffer 880 by a signal 871.
Output buffer 880 receives signal 871 from pulse generator 870 and forwards this 2o signal as signal 881 to a motor driver 890, electrically buffering the control system SUBSTITUTE SHEET ( rule 26 ) from motor 40. Finally, motor driver 890 drives motor 40 in a conventional manner, motor 40 driving lead screw 44 of syringe pump 30.
In addition to generating outputs for driving motor 40, controller 815, through control board 810 collects inputs from three distinct sensor areas.
First, s encoder 39 (noted above) monitors the rotation of the distal end of lead screw 44 as shown in F1G. 4 to verify the integrity of drive mechanism 36.
Referring again to FIGS. 3 and 4, drive mechanism 36 is depicted having encoder 39 operatively coupled to the distal end of lead screw 44. Encoder 39 senses the rotation of lead screw 44 and convel-ts that input to a measurement of the pulses o generated by motor 40, allowing for the reduction effected by reducer 42.
Specifically, the number of turns, and the relative positioning between the fixed portion of the pump and the lead screw 44 is determined. The distance or measure of the movement of screw 44 relative to its starting position is then calculated. This value is then forwarded as a signal 801 to a counter 817, and is eventually compared to a value 1 s supplied by counter 817. Counter 817 determines the relative movement that should have been made by lead screw 44, by counting the number of pulses generated and fed to motor 40 which moves lead screw 44. This counter signal, as well as the original signal 801, are forwarded to controller 815 as signal 802, which compares these two values.
2o Since lead screw 44 should have moved a distance equal to the distance it was instructed to move, these values should be equal. A disparity (allowing for a SUBSTITUTE SHEET ( rule 26 ) defined tolerance) between these two values, detected by controller 815, indicates that icad screw 44 is not moving as it should be, and that drive mechanism 36 could be malfunctioning in some respect. In this event, controller 815 will shut down probe 200. Alternatively, in the event that probe 200 may be operated without coolant fluid s delivery for a time certain without a negative effect to the patient, the controller can be constructed to sound an alarm that warns the user of a problem in drive mechanism 36.
The second sensor area includes force sensor 70 (noted above) which may be used to monitor the upper and lower limits of force or pressure applied to syringe 50. Where the detected force or pressure is less than a lower limit, this can ~ o mean that either: ( I ) syringe 50 is not properly positioned within cradle 46 or antisiphon catch 65; (2) syringe 50 does not contain any saline; (3) syringe 50, conduit 98, or ultrasound probe 200 has a leak or has not been properly assembled; (4) pusher block 34 is jammed or not functioning properly; or (S) the operator has placed the wrong type or size syringe 50 in cradle 46. Where the detected force or pressure is is greater than an upper limit, the controller may detect when syringe 50, conduit 98, or the fluid passage of ultrasound probe 200 is blocked, or where the operator has used the wrong type or size syringe 50.
In short, because coolant is required to maintain ultrasound probe 200 below a designated temperature, in the event that coolant delivery is interrupted, probe 20 200 is advantageously deactivated. Accordingly, in a preferred embodiment of the invention, cooling system 500 monitors situations where the force or pressure is less SUBSTITUTE SHEET ( rule 26 ) than the lower force or pressure limit and situations where force or pressure is greater than the upper force or pressure limit.
To prevent operation of ultrasound probe 200 in the absence of coolant delivery, according to a preferred embodiment of the invention, the controller s monitors the pressure felt by pusher block 34 as it drives syringe plunger 54 to determine if a blockage or rupture has occurred anywhere in cooling system 500, or if syringe 50 runs out of fluid.
Referring to FIGS. 7 and 8, as pressure is applied to pressure plate 35, it flexes slightly thereby transferring force to force sensor 70. The resistance of force o sensor 70 changes as the traces of force sensor 70 come in contact with a layer of conductive rubber. Refernng to FIG. 20, the value measured by force sensor 70 is then fed as signal 803 through an operational amplifier 820 to increase the value of the signal as compared to a reference signal, and is then fed into an analog-to-digital (A/D) converter 830 along line 804. Converter 830 receives this amplified analog s signal from operational amplifier 820 and converts it into a digital signal, which is in turn fed to controller 815 along line 805 through control board 810. If the value of the force sensor reading is determined by controller 81 S to be outside a predetermined range, indicating a problem with the pump, the system is shut down.
The range of pressure may be defined based on the force detected by 2o force sensor 70 for a number of different syringe sizes and the defined ranges stored within the controller for comparison. A user may identify the syringe size by inputting SUBSTITUTE SHEET ( rule 26 ) the syringe size into the user interface 148 on display panel 7J {FIG. 1 ).
For a given syringe, the cross-sectional area of the barrel is known, and therefore knowing the force applied to the plunger flange permits the calculation of the pressure applied to the plunger flange. In a preferred embodiment of the current invention, an operating s range of between 28 and 38 psi is designated.
If the force sensor output is outside a defined range, the controller automatically ceases the delivery of energy to ultrasound probe 200.
Alternatively, in the event that probe 200 may be operated without coolant fluid delivery for a time certain without a negative effect on the patient, the controller may sound an alarm to warning the user of a problem with coolant system 500.
Refernng to FIG. 20, the third sensor area includes sensors which monitor fluid remaining in the syringe. Specifically, a first sensor 840 detects when there is approximately 10 ml of fluid remaining in the syringe. When this condition is reached, a signal 806 is sent to an input buffer 860, which sends a signal 807 to is controller 8I5 through control board 810 to warn controller 815 that the fluid level is running low. When the syringe is finally empty, a second sensor 850 detects this state and sends a signal 808 to an input buffer 860. At this stage, pulse generator 870 is immediately shut down without delay due to the dangerous condition presented by an empty syringe. Signal 808 is also sent to controller 815 through control board 810 to 2o warn controller 81 S that the fluid has run out. As a result, controller 815 can shut SUBSTITUTE SHEET ( rule 26 ) down the remainder of the system. Input buffer 860 comprises appropriate logic whereby first and second signals 80C and 808 are properly sent to control board 810.
If any of the sensors in these three sensor areas indicate that a problem exists in cooling system 500, the system is shut down, and controller 815 instincts s pulse generator 870 not to send any other signals to motor 40. Thus, full operation of syringe pump 30 is disabled.
Systems in accordance with the invention include a way to adjust the force applied to syringe plunger 54 based on the force being measured at plunger 54.
In conventional syringe pumps, the rate of fluid flow is adjusted based on feedback t o obtained from motor shaft 41. However, basing feedback on the speed of motor shaft 41 may not take into account inefficiencies or losses elsewhere in cooling system 500.
As a result of the ineffective earlier method, applications that require a narrow range of acceptable flow rates or pressures cannot be accommodated suitably with a cooling systems adapted to have the ability to finely tune the force applied to syringe plunger i s 54.
Accordingly, in another embodiment of the invention, the output from force sensor 70 may be fed to the controller so that the motor input signal may be modified to make fine adjustments in the speed at which motor 40 drives drive mechanism 42. Adjusting motor speed effectively alters the rate at which pusher block 20 34 travels and hence the flow rate and pressure of fluid delivered by syringe pump 30.

SUBSTITUTE SHEET ( ruie 26 ) .

Further, it was deternzincd that unlike the syringe pumps used to deliver medicines, where the application involved the delivery of ultrasound energy, coolant delivery is only required during the activation of the ultrasound probe. Thus, given the relatively high flow rate to maintain the ultrasound probe temperature, and the s limitations created by syringe sizes, it was determined that synchronizing the operation of probe 200 with the delivery of the coolant was desirable to assure the reliability of coolant system 500. For example, in a preferred embodiment of the invention, syringe 50 is capable of delivering CO ml of fluid. One procedure performed by ultrasound probe 200 requires 20 to 30 ml of fluid during the time the probe is activated.
~o Therefore, there is a need to conserve coolant fluid so that an application of probe 200 need not be interrupted while a patient is undergoing a procedure.
Accordingly, coolant delivery is enabled by controller 815 only during the operation of the probe. That is, controller 815 signals motor 40 to drive syringe pump 30 at a high rate only during probe activation. During activation of probe 200, in 1 s a preferred embodiment of the invention, syringe plunger 54 is driven at about 33 psi, and fluid is delivered at a rate of about 1 U ml/minute. Otherwise, prior to the introduction of probe 200 into a patient's body, motor 40 is energized to drive syringe pump 30 in an idling mode at a low speed so as to merely create a positive fluid flow through probe 200 and prevent formation of air bubbles therein. In a preferred 2o embodiment, fluid is provided at 1 ml/minute when probe 200 is in an idling mode. In this manner, probe 200 is prevented from introducing air into a patient's vasculature SUBSTITUTE SHEET ( rule 26 ) when probe 200 is introduced into a patient's body and prevents blood from backflushing down the probe.
It was also determined that assembling the controller, the coolant system, and the ultrasound probe required coordinating multiple lines sometimes over a substantial distance. As such, the user often twisted the cable that connects the transducer to the proximal end of the probe. Referring to FIG. 17, a prior art transducer connector 600 is depicted as connecting cable 602 to transducer 601. Such a connector in the prior art was an integral part of transducer 601. That is, cable 602 was hard-wired to transducer 601. Because transducer 601 is screwed onto the to ultrasound device horn (not shown), a twist in cable 602 causes an axial force to be applied to the ultrasound device transmission wire, which is connected to the ultrasound horn. Thus, when transducer 601 is attached to the horn, an axial force is transferred to the transmission wire, which in turn stresses the integrity of the joint between the wire and the sheathing. if this joint is compromised, coolant will escape 1 s and thus not cool the probe.
To prevent stress on the joint, it was determined that a releasable, cam-driven quick disconnect be provided between the ultrasonic horn and the transducer to prevent axial displacement of the horn relative to the sheathing in the event that the transducer cable became twisted. Such an arrangement is depicted in FIG. 18.
2o Disconnect 700 is shown as releasable from transducer 701. In this manner, any twist in cable 702 is not transferred to the ultrasound probe.

SUBSTITUTE SHEET ( rule 26 ) It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in the above methods and constructions without departing from the spirit and scope of the invention, it is intended that all matter contained in the s above-description or shown in the accompanying drawings be interpreted as illustrative and not in a limiting sense. For example, the current invention and the teachings of this specification can also be used in applications other than medical, such as pipe cleaning, which one skilled in the art will readily recognize.
Thus, while there have been shown and described and pointed out to fundamental novel features of the invention as applied to preferred embodiments thereof, it will be understood that various omissions and substitutions and changes in the form and details of the disclosed invention may be made by those skilled in the art without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.
is SUBSTITUTE SHEET ( rule 26 )

Claims (13)

WHAT IS CLAIMED IS:

1. An ultrasound treatment system comprising:
an energy source for supplying ultrasound energy;
an ultrasound probe, for receiving ultrasound energy from the energy source and for applying ultrasound energy to a treatment site, the ultrasound probe including at least one transmission member and a fluid passageway for cooling the transmission member;
a fluid delivery system, comprising:
a frame;
a drive mechanism mounted within the frame; the drive mechanism comprising a lead screw and a motor operatively coupled to the lead screw;
a pusher block mounted on the frame and engaged with the drive mechanism, the pusher block comprising a housing, a biasing assembly disposed within the housing for applying a biasing force to bias the pusher block into engagement with the lead screw, a lock assembly constructed to prevent disengagement of the pusher block form the lead screw when forces act to overcome the biasing force and disengage the pusher block and lead screw; and a syringe mounted within the frame, and adapted to supply fluid to the passageway, the syringe formed with a reservoir for storing fluid and a syringe plunger for dispensing the fluid from the reservoir when the syringe plunger is depressed thereinto, the pusher block being coupled with the syringe plunger for depressing the syringe plunger into the reservoir when the drive mechanism is activated to drive the pusher block.

2. The ultrasound treatment system of claim 1, wherein the lock assembly is disposed within the housing, and comprises an actuator coupled with the housing and being positionable between a first locked position at which the lock assembly prevents the disengagement of the pusher block from the lead screw, and a second, unlocked position at which the lock assembly permits the disengagement of the pusher block from the lead screw.

3. The ultrasound treatment system of claim 2, wherein the pusher block comprises a pusher block plunger assembly comprising a pushbutton for displacement of the plunger assembly between a first locked position in which the pusher block is engaged with the lead screw, and a second unlocked position in which the pusher block is disengaged from the lead screw.

4. The ultrasound treatment system of claim 1, wherein the syringe further comprises a barrel having a distal end and a proximal end, and an outlet is formed at the distal end thereof, the plunger formed with a distal end having a distal flange sized to fit within the proximal end of the barrel, and a proximal end having a proximal flange releasably connected with the pusher block.

5. A method of delivering ultrasound energy to a location with an ultrasound probe having at least one transmission member for transmitting ultrasound energy, a passageway for delivering cooling fluid to the transmission member and a pump for supplying fluid to the passageway, the pump including a syringe for storing cooling fluid and expelling such fluid to the passageway, the syringe having a plunger coupled to a pusher block, the pusher block having a pusher block plunger assembly, the pusher block being engaged with a lead screw for advancing the pusher block against the plunger, and held against the lead screw with a biasing mechanism, comprising the steps of:
(a) disposing fluid within the syringe;
(b) disengaging the pusher block from the lead screw by applying a relatively light disengaging force to the pusher block plunger assembly;
(c) positioning the pusher block against the syringe plunger;
(d) coupling the syringe plunger to the pusher block;
(e) biasing the pusher block against the lead screw by application of a relatively large biasing force by the biasing mechanism, the biasing force being larger than the disengaging force; and (f) transmitting ultrasound energy with an ultrasound transmission member while advancing the pusher block against the syringe plunger, by turning the lead screw.

6. The method of delivering ultrasound energy of claim 5, wherein the biasing mechanism comprises two wings and a push button, wherein the light force is applied by pulling up on the wings and pushing a push button; and the large force is applied by permitting the spring to bias the pusher block against the lead screw.

7. An ultrasound treatment system comprising:
an energy source for supplying ultrasound energy;
an ultrasound probe, for receiving ultrasound energy from the energy source and for applying ultrasound energy to a treatment site, the ultrasound probe including at least one transmission member and a fluid passageway for cooling the transmission member;
a fluid delivery system, comprising:
a frame;
a drive mechanism mounted within the frame; the drive mechanism comprising a lead screw, having a first end and a second end, and a motor operatively coupled to the first end of the lead screw;
a sensor connected to the second end of the lead screw for monitoring the speed of the lead screw to verify the integrity of the drive mechanism.

8. A fluid delivery system, comprising:
a frame;

a drive mechanism mounted within the frame; the drive mechanism comprising a lead screw and a motor operatively coupled to the lead screw; and a pusher block mounted on the frame and engaged with the drive mechanism, the pusher block comprising a housing, a biasing assembly disposed within the housing for applying a biasing force to bias the pusher block into engagement with the lead screw, a lock assembly constructed to prevent disengagement of the pusher block form the lead screw when forces act to overcome the biasing force and disengage the pusher block and lead screw.

9. The fluid delivery system of claim 8, wherein the lock assembly is disposed within the housing, and comprises an actuator coupled with the housing and being positionable between a first locked position at which the lock assembly prevents the disengagement of the pusher block from the lead screw, and a second, unlocked position at which the lock assembly permits the disengagement of the pusher block from the lead screw.

10. The fluid delivery system of claim 9, wherein the pusher block comprises a pusher block plunger assembly comprising a pushbutton for displacement of the plunger assembly between a first locked position in which the pusher block is engaged with the lead screw, and a second unlocked position in which the pusher block is disengaged from the lead screw.

11. The fluid delivery system of claim 8, comprising a syringe mounted within the frame, and adapted to supply fluid to the passageway, the syringe formed with a reservoir for storing fluid and a syringe plunger for dispensing the fluid from the reservoir when the syringe plunger is depressed thereinto, the pusher block being coupled with the syringe plunger for depressing the syringe plunger into the reservoir when the drive mechanism is activated to drive the pusher block.

12. The fluid delivery system of claim 8, wherein the syringe further comprises a barrel having a distal end and a proximal end, and an outlet is formed at the distal end thereof, the plunger formed with a distal end having a distal flange sized to fit within the proximal end of the barrel, and a proximal end having a proximal flange releasably connected with the pusher block.

13. A fluid delivery system comprising:
a frame;
a drive mechanism mounted within the frame; the drive mechanism comprising a lead screw, having a first end and a second end, and a motor operatively coupled to the first end of the lead screw;
a sensor connected to the second end of the lead screw for monitoring the speed of the lead screw to verify the integrity of the drive mechanism.