METHOD AND APPARATUS FOR TREATMENT OF TISSUES WITH FLUID JETS

Abstract: A method and apparatus for removing tissue with a high-pressure fluid jet. In one embodiment, a high-pressure primary fluid is mixed with a secondary fluid to produce a fluid jet having a reduced level of coherence. The secondary fluid can be introduced either by entrainment from the ambient or reservoir or from a pressure source or by means of a vacuum pump. The mass flow and/or pressure of either or both of the primary and secondary fluids can be controlled to remove a selected portion of tissue. The tissue can be selected to include human or animal tissue, such as skin or bone tissue, vegetable tissue, or other types of tissue.

Description: METHOD AND APPARATUS FOR TREATMENT OF TISSUES WITH FLUID JETS TECHNICAL FIELD This invention relates to methods and devices for treating tissues, such as skin, with high pressure fluid jets. BACKGROUND OF THE INVENTION Plastic surgery refers generally to surgical repair or replacement of lost, injured, or deformed parts of the body by a transfer of tissue. One aspect of plastic surgery involves removing layers of unwanted skin, for physiological or aesthetic purposes. Several conventional techniques have been devised to surgically remove skin. Such techniques include burning the skin with a laser or grinding the skin with a mechanical grinder. A disadvantage of conventional laser techniques is that they can generate high temperatures at the removal site, which can in turn result in tissue damage that takes long periods of time to heal. One disadvantage of mechanical grinders is that they are noisy, which may be unsettling to the patient. Another disadvantage of mechanical grinders is that it can be difficult for users to control the depth and lateral extent of the cut performed by the grinder. This in turn can reduce the accuracy with which the surgery is performed. Accordingly, there exists a need in the art for improved devices and techniques for accurately removing skin without overheating the surrounding tissue. The present invention fulfills these needs, and provides further related advantages. SUMMARY OF THE INVENTION Briefly, the present invention provides a method and apparatus for removing a portion of tissue with a high pressure fluid jet. In one embodiment, the apparatus can include a nozzle body having a nozzle orifice coupled to a source of a first fluid. The apparatus can further include a conduit having a channel in fluid communication with the nozzle orifice. The channel includes an exit opening for directing the first fluid, and at least one of the nozzle body and the conduit can include an aperture downstream of the nozzle orifice and upstream of an exit opening of the conduit. The aperture can be in fluid communication with a source of a second fluid to introduce the second fluid into the conduit. In one embodiment, a ratio of a length of the conduit channel to a mean diameter of the exit opening of the conduit can be at least approximately 10 for mixing the second fluid with the first fluid to control the coherence of a fluid jet exiting the conduit. In another embodiment, the nozzle body can be configured to withstand forces generated by the first fluid when the first fluid has a static pressure of up to 5,000 psi. In one embodiment, the aperture is coupled to a pressurized source of the second fluid for delivering the second fluid to the conduit. In another embodiment, the aperture can be coupled to a vacuum source for drawing the second fluid into the conduit either through a separate aperture or through the exit opening of the conduit. In further aspects of this embodiment, the second fluid can be drawn from a separate source of fluid, or from the ambient environment surrounding the apparatus. In a method in accordance with one embodiment of the invention, the fluid jet exiting the conduit can be directed to any animal or vegetable tissue for removing a portion of the tissue. In one aspect of this embodiment, the nozzle body through which the fluid jet passes can be supported by hand. The second fluid can be controllably entrained with the first fluid to produce a fluid jet having a desired effect on the tissue. For example, the method can include controlling the pressures of the first and second fluids to reduce the coherence of the fluid jet and increase a number of discrete fluid droplets in the fluid jet. In a further aspect of this embodiment, the flow of the second fluid can be initiated prior to the flow of the first fluid to prevent the first fluid alone from striking the tissue. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a partially schematic, partial cross-sectional side elevation view of an apparatus in accordance with an embodiment of the invention. Figure 2 is a partially schematic, partial cross-sectional side elevation view of an apparatus having a plurality of axially spaced apart entrainment apertures in accordance with another embodiment of the invention. Figure 3A is a partial cross-sectional side elevation view of an apparatus having a removable cartridge in accordance with still another embodiment of the invention. Figure 3B is a detailed side elevation view of a portion of the apparatus shown in Figure 3A. Figure 4 is a partial cross-sectional side elevation view of an apparatus having two removable cartridge assemblies in accordance with yet another embodiment of the invention. Figure 5A is an exploded, partial cross-sectional side elevation view of an apparatus having a removable aperture housing in accordance with still another embodiment of the invention. Figure 5B is a partial cross-sectional side elevation view of the assembled apparatus shown in Figure 5A. DETAILED DESCRIPTION OF THE INVENTION An apparatus 10 in accordance with an embodiment of the invention is shown in Figure 1. The apparatus 10 includes a supply conduit 40 that delivers a primary fluid to a nozzle 30. The primary fluid exits the nozzle 30 and can entrain a secondary fluid through secondary flow apertures 22. The primary and secondary fluids can together pass into an axially elongated delivery conduit 50 and exit the delivery conduit 50 in the form of a fluid jet 90 that impacts tissue 80 below to remove a portion of the tissue. The apparatus 10 can be manipulated by hand, or remotely via a gantry 95 or other remote positioning device, shown schematically in Figure 1. More particularly, the apparatus 10 can include a primary fluid supply 41 coupled to the supply conduit 40. The primary fluid supply 41 can include a liquid-phase fluid, such as water, saline, or other fluids that are suitable for controlled removal of a portion of the tissue 80. For example, in one embodiment, the primary fluid can include anti-allergens to reduce the likelihood of an allergic reaction in the tissue 80 and/or antibiotics to reduce the likelihood of an infection in the tissue 80. The primary fluid supply 41 can also include pressurizing means, such as an intensifier or a pump, that can pressurize the primary fluid up to or beyond approximately 5,000 psi. In a preferred embodiment, the primary fluid supply 41 can pressurize the primary fluid to between 500 and 2,500 psi. The particular pressure chosen can depend on the characteristics of the tissue 80 and on the intended effect of the fluid jet 90 on the tissue 80. For example, the pressure can be relatively high for making deep cuts in the tissue 80, or for cutting relatively hard tissue, such as bone tissue. Alternatively, the pressure can be relatively low for making shallow cuts in the tissue 80 and/or for cutting softer tissues, such as human skin. The supply conduit 40 connects the primary fluid supply 41 with the nozzle 30. The nozzle 30 can have a nozzle orifice 33 that extends through the nozzle 30 from an entrance opening 31 to an exit opening 32. In one embodiment, the nozzle orifice 33 can have a generally axisymmetric cross- sectional shape extending from the entrance opening 31 to the exit opening 32, and in other embodiments, one or more portions of the nozzle orifice 33 can have generally elliptical or other cross-sectional shapes for generating fluid jets having corresponding non-axisymmetric cross-sectional shapes. In one embodiment, an entrainment region 34 is located downstream of the nozzle 30. In a preferred aspect of this embodiment, the entrainment region 34 has a flow area that is larger than that of the nozzle orifice 33 to allow for entraining the secondary fluid through the secondary flow apertures 22. In the embodiment shown in Figure 1, four circular secondary flow apertures 22 (three of which are visible in Figure 1) are spaced apart at approximately the same axial location relative to the nozzle 30. In alternate embodiments, more or fewer secondary flow apertures 22 having the same or other cross-sectional shapes can be positioned anywhere along a flow passage extending downstream of the exit opening 32. In one embodiment, the secondary flow apertures 22 have diameters of between approximately 0.01 inches and 0.03 inches. In other embodiments, the secondary flow apertures 22 can have other shapes and sizes. The secondary flow apertures 22 can be oriented generally perpendicular to the direction of flow through the entrainment region 34 (as shown in Figure 1), or at an acute or obtuse angle relative to the flow direction, as is discussed in greater detail below with reference to Figure 3 A. In the embodiment shown in Figure 1, the secondary flow apertures 22 communicate directly with the ambient environment outside the supply conduit 40. Accordingly, air (or any other gas adjacent the secondary flow apertures) can be drawn directly from the ambient environment into the entrainment region 34. In other embodiments, discussed in greater detail below with reference to Figures 2-5B, the secondary flow apertures 22 can be coupled to a controlled source of secondary fluid. In any case, the effect of the secondary fluid on the fluid jet 90 can be at least partially break up the fluid jet so that the fluid jet includes discrete droplets of primary fluid separated by regions of secondary fluid. This effect has been observed to reduce the coherence or focus of the fluid jet 90 so that the fluid jet can be used to controllably remove a portion of the tissue 80 to a selected depth, in contrast with some conventional fluid jets which, if directed toward the tissue 80, would simply cut directly through the tissue. The delivery conduit 50, positioned downstream of the secondary flow apertures 22, can receive the primary and secondary fluids and direct the fluid jet 90. Accordingly, the delivery conduit 50 can include an upstream opening 54 positioned downstream of the secondary flow apertures 22, and a downstream opening 55 through which the fluid jet 90 exits. A channel 53 extends between the upstream opening 54 and the downstream opening 55. In the embodiment shown in Figure 1, the delivery conduit 50 can be formed integrally with the supply conduit 40 and in other embodiments, discussed in greater below with reference to Figures 3A-5B, the delivery conduit 50 can be removably coupled to the supply conduit 40. In one embodiment, the minimum flow area or mean diameter of the channel 53 is larger than the minimum flow area or mean diameter of the nozzle orifice 33, to allow the secondary fluid to be entrained by the primary fluid. As used herein, the mean diameter refers to the lineal dimension which, when squared, multiplied by pi and divided by four, is equal to the flow area. For example, in one embodiment, the minimum mean diameter of the flow channel 53 can be between three and five times the minimum mean diameter of the nozzle orifice 33. In another embodiment, the nozzle orifice 33 can have a minimum diameter of approximately 0.004 inch and the flow channel 53 of the delivery conduit 50 can have a minimum diameter of approximately 0.080 inch. The delivery conduit 50 can also have an overall length (between the upstream opening 54 and the downstream opening 55) of between 10 and 200 times the mean diameter of the downstream opening 55, to permit sufficient mixing of the secondary fluid with the primary fluid. In one embodiment, for example, the delivery conduit 50 can have a length of approximately 4 inches when the downstream opening 55 has a diameter of 0.080 inch. In operation, the apparatus 10 is positioned proximate to the tissue 80 such that the downstream opening 55 of the delivery conduit 50 is located a selected offset distance 60 away from the tissue. The apparatus 10 can be positioned either by hand or remotely via the gantry 95 or other mechanical positioning device. The primary fluid is pressurized to between approximately 500 psi and approximately 2,500 psi (preferably about 1,500 psi when the tissue 80 is human skin). The primary fluid is then pumped from the primary fluid supply 41 through the supply conduit 40 and into the entrainment region 34 where it entrains the secondary fluid through the secondary flow apertures 22. The primary and secondary fluids proceed through the entrainment region 34 and the delivery conduit 50, exit the conduit 50 as a fluid jet 90, and strike the tissue 80. The apparatus 10 can then be traversed relative to the tissue 80 (or vice versa) to remove a portion of the tissue 80 to a selected depth along a selected path. For example, where the tissue 80 includes skin, the apparatus 10 can be traversed at a selected speed which, when taken together with the pressure and composition of the fluid jet 90 and the characteristics of the skin, causes one or more layers of skin to separate from the underlying layers. Alternatively, the apparatus 10 can be stationary relative to the tissue 80 while the fluid jet 90 is pulsed or otherwise intermittently directed toward the tissue. Accordingly, the user can examine the tissue 80 between pulses of the fluid jet 90 to determine when a selected amount of the tissue has been removed. The user can then move the apparatus 10 to a different location relative to the tissue and repeat the process. An advantage of the apparatus 10 discussed above with reference to Figure 1 is that it can effectively remove a portion of the tissue 80 without burning the surrounding tissue. Another advantage is that users can control the pressure and/or mass flow rate of the primary fluid and the traverse rate of the apparatus 10 to control the amount of tissue removed, without simply cutting completely through the tissue, as can be the case with some conventional fluid jet devices. Yet another advantage is that users can control the pressure of the primary fluid to remove portions of a variety of tissue types. For example, users can remove external skin, tissue from internal soft organs, or outer layers of bone tissue to access bone marrow for transplants. Still another advantage is that the device 10 can be sufficiently versatile to treat human tissue, animal tissue or any organic tissue. For example, in one alternate embodiment, the apparatus 10 can be used to remove the skin from fruits, such as peaches or tomatoes. Yet another feature of an embodiment of the apparatus 10 is that the fluid jet 90 can have approximately the same level of coherence over a range of stand-off distances 60, unlike some conventional fluid jets for which the coherence (and therefore the cutting effectiveness of the fluid jet) is a function of the stand-off distance 60. This is advantageous because users can more readily use the apparatus 10 to treat tissue 80 having a varying topography, without having to maintain as precise a control over the stand-off distance 60. Figure 2 is a partially schematic, partial cross-sectional side elevation view of an apparatus 110 having two manifolds 152 (shown as an upstream manifold 152a and a downstream manifold 152b) adjacent a delivery conduit 150 in accordance with another embodiment of the invention. The manifolds 152a and 152b can be coupled to corresponding secondary fluid supplies 151, shown in Figure 2 as an upstream secondary fluid supply 151a and a downstream secondary fluid supply 151b. In one embodiment, the upstream and downstream secondary fluid supplies 151 can supply different secondary fluids, and in an alternate embodiment the upstream and downstream secondary fluid supplies can supply the same secondary fluid. In a further aspect of this alternate embodiment, the upstream and downstream secondary fluid supplies 151a and 151b can be combined to form a single secondary fluid supply. In any case, the secondary fluid can include any suitable gas, for example, air, C0 2 or oxygen. An advantage of selecting oxygen as the secondary fluid is that the oxygen may hasten the healing of the tissue 80 surrounding the region at which the fluid jet 90 impacts the tissue. The pressure of the secondary fluid can be in the range of approximately 5 psi to approximately 30 psi (preferably about 20 psi), or alternatively, can have any value that reduces the coherence of the fluid jet 90 to a level that allows for controlled removal of the tissue 80. The upstream manifold 152a can include upstream flow apertures 122 a that introduce the secondary fluid to an upstream entrainment region 134a and the downstream manifold 152b can include downstream flow apertures 122b that introduce the secondary fluid to a downstream entrainment region 134b. In one embodiment, the upstream and downstream apertures 122a and 122b can have the same diameter. In another embodiment, the upstream apertures 122a can have diameters different than those of the downstream apertures 122b to entrain an amount of secondary fluid in the upstream entrainment region 134a that is different than the amount of secondary fluid entrained in the downstream entrainment region 134b. In the embodiment shown in Figure 2, the flow area of the delivery conduit 150 decreases slightly downstream of the upstream entrainment region 134a. In alternate embodiments, the flow area of the delivery conduit 150 can remain constant between the upstream and downstream entrainment regions 134a and 134b, or can increase between the two entrainment regions. An advantage of the apparatus 110 shown in Figure 2 is that it may be easier to control the characteristics of the fluid jet 90 by supplying the secondary fluid at two (or more) axial locations downstream of the nozzle 30. Furthermore, the upstream and downstream manifolds 152a and 152b may be coupled to different secondary fluid supplies 151a and 151b to produce a fluid jet 90 having a selected composition and a selected level of coherence. Alternatively, the secondary fluid supplies 151a and 151b can supply similar fluids but at different pressures and/or mass flow rates to achieve the desired level of control over the coherence of the fluid jet 90. In an alternate embodiment, the upstream secondary fluid supply 151a can be operated in reverse (i.e., as a vacuum source rather than as a pump) to draw a vacuum through the delivery conduit 150 and through the upstream apertures 121a. In one aspect of this embodiment, the downstream secondary fluid supply 151b can supply the secondary fluid that is drawn up through the delivery conduit 150 to the upstream secondary fluid supply 151a. In another aspect of this embodiment, the downstream secondary fluid supply 151b, downstream apertures 122b, and downstream manifold 152b can be eliminated and the secondary fluid can be drawn from the ambient environment through the downstream opening 155 of the delivery conduit 150 and upwardly through the delivery conduit 150. In either case, the effect of drawing a vacuum through the delivery conduit 150 has been observed to be similar, over selected pressure ranges, to that of pumping secondary fluid into the delivery conduit 50, i.e., to reduce the coherence of the resulting fluid jet 90. An advantage of drawing the secondary fluid directly from the ambient environment through the downstream opening 155 of the delivery conduit 150 is that the need for the downstream secondary fluid supply 151b, the downstream apertures 122b, and the downstream manifold 152b can be eliminated, resulting in a simpler device. Conversely, an advantage of drawing the secondary fluid from the downstream fluid supply 151b is that the characteristics of the secondary fluid can be more easily controlled by selecting the fluid provided by the downstream secondary fluid supply 151b. Furthermore, the likelihood for entraining debris caused by the impact of the fluid jet 90 on the tissue 80 can be reduced by entraining fluid through the downstream apertures 122b rather than through the downstream conduit opening 155. Figure 3A is a partial cross-sectional side elevation view of an apparatus 210 having a nozzle 230 and a delivery conduit portion 250 housed in a removable cartridge 277, in accordance with another embodiment of the invention. The cartridge 277 is removably attached to a supply conduit 240, which is annularly disposed within a manifold 252. The manifold 252 can include a manifold entrance 256 coupled to the secondary fluid supply 151a (Figure 2) and the supply conduit 240 can be coupled to the primary fluid supply 41 (Figure 2). The supply conduit 240 can have a downstream end 244 with threads 242 that engage corresponding threads 278 of the cartridge 277. In one embodiment, the cartridge 277 can include wrench slots 262 for receiving a wrench to loosen or tighten the cartridge 277. In other embodiments, the apparatus 210 can include other means for removably attaching the cartridge 277. The cartridge 277 can include at its upstream end a nozzle support portion 220 that supports the nozzle 230. As is shown in greater detail in Figure 3B, the nozzle support portion 220 has a nozzle opening 221 into which the nozzle 230 fits. A seal 224 seals the interface between the nozzle 230 and the nozzle support portion 220. Accordingly, the nozzle 230 can be removed from the support portion 220 and replaced, if desired. As was discussed above with reference to Figure 1, the nozzle 230 can include a nozzle orifice 233 having an upstream entrance opening 231 and a downstream exit opening 232. In one embodiment, the entrance opening 231 can be selected to have a diameter of between 0.003 inch and 0.005 inch, and in other embodiments the entrance opening 231 (or the minimum diameter of the nozzle orifice 233) can have other sizes. In one embodiment, the nozzle 230 can include sapphire, diamond or another extremely hard material. In another embodiment, when the pressures produced by the primary fluid supply 41 (Figure 1) are sufficiently low, the nozzle 230 can include a softer material, such as stainless steel. Returning to Figure 3A, the cartridge 277 can further include secondary flow apertures 222 positioned downstream of the nozzle support portion 220. As is shown in Figure 3 A, the secondary flow apertures 222 can be canted so as to form an acute angle with the direction of flow passing through the cartridge 277. In other embodiments, the secondary flow apertures 222 can be generally perpendicular to the direction of flow (as shown in Figures 1 and 2) or the secondary flow apertures can form an obtuse angle with the flow direction. In any case, the apparatus 210 can include a conduit seal 261 that seals the interface between the manifold 252 and the delivery conduit portion 250 of the cartridge 277 downstream of the secondary flow apertures 222 to prevent the secondary fluid from leading therebetween. An advantage of the apparatus shown in Figures 3A-B is that the annular arrangement of the manifold 252 and the supply conduit 240 results in a more compact unit that users can more easily manipulate and control during operation. Another advantage is that the cartridge 277 can be easily removed from the apparatus 210. Accordingly, users can vary the size and orientation of the secondary flow apertures 222 and the delivery conduit portion 250 by exchanging one cartridge 277 for another cartridge having different dimensions. Furthermore, users can easily remove the cartridge 277 to access the nozzle 230. Accordingly, users can easily exchange the nozzle 230 with one having an orifice 233 with different dimensions, and/or users can easily replace the nozzle 230 when the nozzle becomes worn during normal use. Figure 4 is a partial cross-sectional side elevation view of an apparatus 310 having two removable cartridge assemblies 377 (shown as an upstream cartridge 377a and a downstream cartridge 377b) in accordance with yet another embodiment of the invention. The apparatus 310 includes a supply conduit 340 that can be coupled to the primary fluid supply 41 (Figure 2) annularly disposed within a manifold 325 that can be coupled to the secondary fluid supply 151a (Figure 2). The upstream cartridge 377b can be positioned at the end of the supply conduit 340. Accordingly, the upstream cartridge 377a can include an external threaded portion 378a that threadably engages a corresponding internal threaded portion of the supply conduit 340. The upstream cartridge 377a houses a nozzle 330 that seals against an annular opening 321 of the upstream cartridge 377a with a seal 324, in a manner similar to that discussed above with reference to Figure 3B. The downstream cartridge 377b includes a delivery conduit portion 350 that extends downstream of the manifold 352. The downstream cartridge 377b can accordingly include an externally threaded portion 378b that threadably engages a corresponding internally threaded portion at the end of the manifold 352. The downstream cartridge 377b can extend annularly around the end of the supply conduit 340 and can include a conduit seal 361 that seals against the outer surface of the supply conduit 340. The downstream cartridge 377b can still further include a plurality of secondary flow apertures 322 positioned downstream of the supply conduit 340 for entraining secondary flow from the manifold 352, in a manner generally similar to that discussed above with reference to Figures 2-3B. Figure 5A is an exploded, partial cross-sectional side elevation view of a modular apparatus 410 in accordance with another embodiment of the invention. Figure 5B is a partial cross-sectional side elevation view of the assembled apparatus 410 shown in Figure 5 A. Referring to Figure 5 A, the apparatus 410 includes a secondary fluid manifold 452 annularly disposed about a supply conduit 440. Both the manifold 452 and the supply conduit 440 are connected to a conduit housing 470, in which the primary and secondary fluids are combined to form the fluid jet 90 (Figure 1). The manifold 452 includes a supply line 454 that can be coupled to the secondary fluid supply 151a (Figure 2). The manifold 452 can also include internal threads 459a that threadably engage corresponding external threads 459b of the conduit housing 470. A manifold passage 458a in the manifold 452 delivers the secondary fluid to the conduit housing 470, as will be discussed in greater detail below. The manifold 452 can also include an aperture 466 through which a portion of the supply conduit 440 projects. The supply conduit 440 includes a threaded fitting 443 that extends through the aperture 466 of the manifold 452 for coupling to the primary fluid supply 41 (Figure 2). The supply conduit 440 further includes an annular seal 457 that seals against the walls of the aperture 466. Downstream of the annular seal 457 are external threads 442a that threadably engage internal threads 442b of the conduit housing 470 to attach the supply conduit 440 to the conduit housing 470. The conduit housing 470 can have a passageway 473 extending therethrough for receiving and mixing the primary and secondary fluids. The passageway 473 can include an upstream portion 473 a that has the internal threads 442b for receiving the supply conduit 440. The passageway 473 can further include a central portion 473b (downstream of the upstream portion 473 a) sized to removably receive a nozzle support 420 and an aperture housing 464. The nozzle support 420 houses a nozzle 430 in a manner generally similar to that discussed above with reference to Figures 3A-B. The nozzle support 420 further includes a channel 425 that directs the primary fluid through the nozzle support 420 from the nozzle 430 to the aperture housing 464. The aperture housing 464 has a channel 425 a aligned with the channel 425 in the nozzle support 420. The aperture housing 464 further includes four apertures 422 (three of which are visible in Figure 5 A) that direct the secondary fluid from the manifold 452 to the channel 425a. Accordingly, the apertures 422 are aligned with passages 458b (in the conduit housing 470) that are in turn aligned with the manifold passage 458a (in the manifold 452). The aperture housing 464 and the nozzle support 420 are biased into position in the central portion 473b of the passageway 473 when the supply conduit 440 is threaded into the conduit housing 470. The passageway 473 in the conduit housing 470 further includes a downstream portion 473 c (downstream of the central portion 473b), sized to receive a delivery conduit 450. Accordingly, the delivery conduit 450 can be inserted into the downstream portion 473 c of the passageway 473 until an upstream end 454 of the delivery conduit 450 abuts a conduit seat 471 of the conduit housing 470. A conduit seal 461, positioned around the delivery conduit 450 and against a seal seat 472 of the conduit housing 470, seals the interface the delivery conduit 450 and the conduit housing 470. The conduit seal 461 and delivery conduit 450 are held in place by a retainer 463 that is disposed about the delivery conduit and is threadably attached to the conduit housing 470. Operation of the device 410 is generally similar to that discussed above with reference to Figures 1-4, and is best understood with reference to Figure 5B. Secondary flow is introduced into the manifold 452 and primary flow is introduced into the supply conduit 440. The secondary flow passes through the apertures 422 where it mixes with the primary flow to form a fluid jet 90 which exits the delivery conduit 450 to treat a portion of tissue 80. In a preferred method of operation, the flow of the secondary fluid is initiated before initiating the flow of primary fluid. In this manner, the tissue 80 will not be subjected to a fluid jet that includes only a high pressure stream of primary fluid. In a further aspect of this method, the apparatus 410 can include a mechanical electrical and/or other type of interlock device that prevents the flow of primary fluid through the supply conduit 440 unless the secondary fluid is flowing into and through the manifold 452. From the foregoing it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the invention. Accordingly, the invention is not limited except as by the appended claims.

Claims: CLAIMS 1. An apparatus for generating a fluid jet for separating a first portion of tissue from a second portion of tissue, the apparatus comprising: a nozzle body configured to be coupled to a source of a first fluid, the nozzle body having a nozzle orifice with a first opening in fluid communication with the source of the first fluid and a second opening downstream of the first opening; and a conduit having a first conduit opening in fluid communication with the second opening of the nozzle orifice, a second conduit opening downstream of the first conduit opening for directing the fluid jet, and a channel extending between the first and second conduit openings, the conduit being configured to be positioned a selected distance from the first portion of tissue, at least one of the nozzle body and the conduit having at least one aperture downstream of the first opening of the nozzle orifice and upstream of the second conduit opening, at least one of the aperture and the second conduit opening being configured to be in fluid communication with a source of a second fluid for introducing the second fluid into the conduit, a ratio of a length of the channel between the first and second conduit openings to a mean diameter of the second conduit opening being at least approximately ten for mixing the second fluid with the first fluid in the channel. 2. The apparatus of claim 1 wherein the nozzle orifice has a minimum flow area and the channel of the conduit has a minimum flow area greater than the minimum flow area of the nozzle orifice. 3. The apparatus of claim 1, further comprising the source of the second fluid, the aperture being coupled to the source of the second fluid. 4. The apparatus of claim 1 wherein at least one of the nozzle body and the conduit are configured to be hand held. 5. The apparatus of claim 1, further comprising a vacuum source, the aperture being coupled to the vacuum source for drawing the second fluid into the conduit through the second conduit opening. 6. The apparatus of claim 5 wherein the second fluid includes ambient gas adjacent the conduit and the second conduit opening is in fluid communication with the ambient gas. 7. The apparatus of claim 1 wherein a ratio of the length of the channel between the first and second conduit openings to the mean diameter of the second conduit opening of the nozzle orifice is approximately twenty-five. 8. The apparatus of claim 1 wherein the nozzle and the conduit are configured to withstand an internal pressure of between approximately 500 psi and approximately 2,500 psi. 9. The apparatus of claim 1 wherein the nozzle orifice has a minimum mean diameter in the range of approximately 0.003 inch to approximately 0.005 inch. 10. The apparatus of claim 1 wherein the second opening of the nozzle orifice is generally round. 11. The apparatus of claim 1 wherein the aperture is a first aperture, further comprising at least a second aperture between the first opening of the nozzle orifice and the second conduit opening. 12. The apparatus of claim 11 wherein the second aperture is positioned downstream of the first aperture. 13. The apparatus of claim 11 wherein the first aperture is positioned at a selected distance from the first opening of the nozzle orifice and the second aperture is spaced apart from the first aperture at approximately the same selected distance from the first opening of the nozzle orifice. 14. The apparatus of claim 1 wherein the aperture has a diameter in the range of approximately 0.01 inch to approximately 0.03 inch. 15. The apparatus of claim 1 wherein the length of the channel is approximately 4.0 inches. 16. The apparatus of claim 1 wherein the second conduit opening has a mean diameter in the range of approximately three to approximately five times a minimum mean diameter of the nozzle orifice. 17. The apparatus of claim 1 wherein the nozzle orifice is aligned with an orifice axis and the aperture is aligned with an aperture axis, further wherein an angle between the aperture axis and the orifice axis is at least approximately 90 degrees. 18. The apparatus of claim 1 wherein the nozzle orifice is aligned with an orifice axis and the aperture is aligned with an aperture axis, further wherein an angle between the aperture axis and the orifice axis is less than approximately 90 degrees. 19. The apparatus of claim 1 wherein the nozzle body and the conduit are removable as a unit from a supply conduit that couples the source of the first fluid with the nozzle body. 20. The apparatus of claim 1, further comprising a nozzle body support having at least one support surface engaging the nozzle body for supporting the nozzle body relative to the conduit. 21. The apparatus of claim 20 wherein the nozzle body, the nozzle body support and the conduit are removable as a unit from a supply conduit that couples the source of the first fluid with the nozzle body. 22. An apparatus for generating a fluid jet for separating a first portion of tissue from a second portion of tissue, the apparatus comprising: a source of a first fluid; a supply conduit coupled to the source of the first fluid; a nozzle body coupled to the supply conduit, the nozzle body having a nozzle orifice with a first opening in fluid communication with the source of the first fluid and a second opening downstream of the first opening; a source of a second fluid; and a delivery conduit having a first conduit opening in fluid communication with the second opening of the nozzle orifice, the delivery conduit further having a second conduit opening downstream of the first conduit opening for directing the fluid jet and a channel extending between the first and second conduit openings, the delivery conduit being configured to be positioned a selected distance from the first portion of the tissue, at least one of the nozzle body and the delivery conduit having at least one aperture coupled to the source of the second fluid, the aperture being downstream of the first opening of the nozzle orifice and upstream of the second conduit opening, a length of the channel between the first and second conduit openings being at least ten times a minimum mean diameter of the nozzle orifice. 23. The apparatus of claim 22 wherein a minimum flow area of the channel is greater than a minimum flow area of the nozzle orifice. 24. The apparatus of claim 22, further comprising the first fluid wherein the first fluid is selected from water and saline. 25. The apparatus of claim 22, further comprising the first fluid wherein the first fluid includes at least one of an antibiotic and an anti-allergen. 26. The apparatus of claim 22, further comprising the second fluid wherein the second fluid includes a gas. 27. The apparatus of claim 22, further comprising the second fluid wherein the second fluid is selected from air, oxygen, and nitrogen. 28. The apparatus of claim 22 wherein the nozzle body and the delivery conduit are removably coupleable as a unit to the supply conduit. 29. The apparatus of claim 22 wherein the nozzle body and the delivery conduit are separately coupleable to the supply conduit. 30. The apparatus of claim 22, further comprising a nozzle body support member having a nozzle support surface engaging the nozzle body, the nozzle body, the nozzle body support member and the conduit being removably coupleable as a unit to the supply conduit. 31. An apparatus for generating a fluid jet for separating a first portion of tissue from a second portion of tissue, the apparatus comprising: a nozzle body configured to be coupled to a source of a first fluid, the nozzle body having a nozzle orifice with a first opening in fluid communication with the source of the first fluid and a second opening downstream of the first opening; and a conduit having a first conduit opening in fluid communication with the second opening of the nozzle orifice, the conduit further having a second conduit opening downstream of the first conduit opening for directing the fluid jet and a channel extending between the first and second conduit openings, the conduit being configured to be positioned a selected distance from the first portion of tissue, at least one of the nozzle body and the conduit having at least one aperture configured to be coupled to a vacuum source for drawing a second fluid into the conduit, the aperture being downstream of the first opening of the nozzle orifice and upstream of the second conduit opening. 32. The apparatus of claim 31 wherein a minimum flow area of the channel is greater than a minimum flow area of the nozzle orifice. 33. The apparatus of claim 31 wherein the second conduit opening has a flow area greater than a minimum flow area of the nozzle orifice. 34. The apparatus of claim 31 wherein the aperture is a first aperture, at least one of the nozzle body and the conduit having a second aperture downstream of the first aperture and upstream of the second conduit opening, the second aperture being sized to draw a selected flow of the second fluid into the conduit when a vacuum is applied to the first aperture. 35. The apparatus of claim 31 wherein the second aperture is coupled to a source of second fluid, further wherein the second fluid is different than an ambient fluid adjacent the conduit. 36. The apparatus of claim 31 wherein the aperture is a first aperture and at least one of the conduit and the nozzle body has a second aperture spaced apart from the first aperture, the first and second aperture being approximately the same distance from the nozzle orifice. 37. An apparatus for generating a fluid jet for separating a first portion of tissue from a second portion of tissue, the apparatus comprising: a nozzle body configured to be coupled to a source of a first fluid having a static pressure of up to 5,000 psi, the nozzle body having a nozzle orifice with a first opening in fluid communication with the source of the first fluid and a second opening downstream of the first opening, the nozzle body being configured to withstand forces generated by the passage of the first fluid through the nozzle orifice; and a conduit having a first conduit opening in fluid communication with the second opening of the nozzle orifice, a second conduit opening downstream of the first conduit opening for directing the fluid jet, and a channel extending between the first and second conduit openings, the conduit being configured to be positioned a selected distance from the first portion of tissue, at least one of the nozzle body and the conduit having at least one aperture downstream of the first opening of the nozzle orifice and upstream of the second conduit opening, at least one of the aperture and the second conduit opening being configured to be in fluid communication with a source of a second fluid for introducing the second fluid into the conduit, a ratio of a length of the channel between the first and second conduit openings to a mean diameter of the second conduit opening being at least approximately ten for mixing the second fluid with the first fluid in the channel. 38. The apparatus of claim 37, further comprising a vacuum source, the aperture being coupled to the vacuum source for drawing the second fluid into the conduit through the second conduit opening. 39. The apparatus of claim 37 wherein a ratio of the length of the channel between the first and second conduit openings to the mean diameter of the second conduit opening of the nozzle orifice is approximately twenty- five. 40. The apparatus of claim 37 wherein the nozzle and the conduit are configured to withstand an internal pressure of between approximately 500 psi and approximately 2,500 psi. 41. The apparatus of claim 37 wherein the nozzle orifice has a minimum mean diameter in the range of approximately 0.003 inch to approximately 0.005 inch. 42. The apparatus of claim 37 wherein the aperture is a first aperture, the apparatus having at least a second aperture between the first opening of the nozzle orifice and the second conduit opening. 43. The apparatus of claim 37 wherein the second conduit opening has a mean diameter in the range of approximately three to approximately five times a minimum mean diameter of the nozzle orifice. 44. The apparatus of claim 37 wherein the nozzle orifice is aligned with an orifice axis and the aperture is aligned with an aperture axis, further wherein an angle between the aperture axis and the orifice axis is at least approximately 90 degrees. 45. The apparatus of claim 37 wherein the nozzle orifice is aligned with an orifice axis and the aperture is aligned with an aperture axis, further wherein an angle between the aperture axis and the orifice axis is less than approximately 90 degrees. 46. The apparatus of claim 37 wherein the nozzle body and the conduit are removable as a unit from a supply conduit that couples the source of the first fluid with the nozzle body. 47. A method for separating a first portion of tissue from a second portion of tissue, comprising: directing a first fluid through a nozzle orifice; controllably entraining a second fluid in the first fluid downstream of the nozzle orifice to form a fluid jet; and directing the fluid jet toward the tissue to separate the first portion of the tissue. 48. The method of claim 47 wherein the first fluid has a coherence upon exiting the nozzle orifice and controllably entraining the second fluid includes controlling the coherence of the first fluid and the fluid jet. 49. The method of claim 47 wherein controllably entraining the second fluid includes reducing a coherence of the fluid jet to increase a number of discrete fluid droplets in the fluid jet. 50. The method of claim 47, further comprising selecting the tissue to include animal tissue. 51. The method of claim 47 wherein selecting the tissue includes selecting the tissue to include skin. 52. The method of claim 51 wherein separating at least a portion of the tissue includes removing a first layer of the skin from a second layer of the skin positioned beneath the first layer of the skin. 53. The method of claim 52, further comprising selecting the skin to include human skin. 54. The method of claim 47, further comprising selecting a pressure of the first fluid to be in the range of approximately 500 psi to approximately 2,500 psi. 55. The method of claim 47, further comprising selecting a pressure of the second fluid to be in the range of approximately 5 psi to approximately 30 psi. 56. The method of claim 47, further comprising selecting the nozzle orifice to have a diameter in the range of approximately 0.003 inch to approximately 0.005 inch. 57. The method of claim 47, further comprising initiating a flow of the second fluid downstream of the nozzle orifice before initiating flow of the first fluid through the nozzle orifice. 58. The method of claim 47, further comprising preventing the first fluid from flowing through the nozzle orifice until after the second fluid is flowing downstream of the nozzle orifice. 59. The method of claim 47, further comprising selecting the first fluid from water and saline. 60. The method of claim 47, further comprising selecting the second fluid to include a gas. 61. The method of claim 47 wherein selecting the second fluid includes selecting the second fluid from air, oxygen, and nitrogen. 62. The method of claim 47 wherein the nozzle orifice extends through a nozzle body and the nozzle body is removably coupled to a delivery conduit downstream of the nozzle orifice, further comprising removing one of the nozzle body and the delivery conduit from the other of the nozzle body and the delivery conduit. 63. The method of claim 47 wherein the first fluid passes from the nozzle orifice into a delivery conduit and exits delivery conduit through an exit aperture, further wherein entraining the second fluid includes supplying the second fluid to the delivery conduit at an entrainment aperture between the nozzle orifice and the exit aperture. 64. The method of claim 47 wherein the first fluid passes from the nozzle orifice into a delivery conduit and exits the delivery conduit through an exit aperture, further wherein entraining the second fluid includes drawing the second fluid into the delivery conduit through the exit aperture and removing at least a portion of the second fluid from the delivery conduit through an entrainment aperture positioned between the nozzle orifice and the exit aperture. 65. The method of claim 47, further comprising controlling a removal rate of the first portion of the tissue by controlling at least one of a pressure of the first fluid, a pressure of the second fluid, a flow rate of the first fluid, a flow rate of the second fluid, and a traverse rate of the fluid jet relative to the first portion of the tissue. 66. The method of claim 47 wherein directing the fluid jet toward the tissue includes pulsing the fluid jet by interrupting a flow of the first fluid through the nozzle orifice. 67. The method of claim 47 wherein the nozzle orifice extends through a nozzle body, further comprising supporting the nozzle body by hand. 68. A method for separating a first portion of tissue from a second portion of tissue, comprising: directing a first fluid through a nozzle orifice to form a fluid jet; passing the fluid jet into a delivery conduit and through an exit opening of the delivery conduit; controllably entraining a second fluid in the fluid jet by drawing the second fluid into the delivery conduit at a point downstream of the nozzle orifice and removing at least a portion of the second fluid from the delivery conduit via an aperture between the nozzle orifice and the exit opening of the delivery conduit; and directing the fluid jet and entrained second fluid toward the tissue to remove the first portion of the tissue. 69. The method of claim 68 wherein controllably entraining the second fluid includes drawing the second fluid through the exit opening of the delivery conduit into the delivery conduit and out of the delivery conduit through the aperture. 70. The method of claim 68 wherein the aperture is a first aperture and controllably entraining the second fluid includes drawing the second fluid into the delivery conduit through a second aperture positioned between the first aperture and the nozzle orifice and removing the second fluid from the delivery conduit through the first aperture. 71. The method of claim 68, further comprising controlling a removal rate of the first portion of the tissue by controlling at least one of a pressure of the first fluid, a pressure of the second fluid, a flow rate of the first fluid, a flow rate of the second fluid, and a traverse rate of the fluid jet relative to the first portion of the tissue. 72. The method of claim 68, further comprising selecting a pressure of the first fluid to be in the range of approximately 500 to approximately 2,500 psi.

Inventors: CRAIGEN STEVEN J, HASHISH MOHAMED A, CRAIGEN, STEVEN, J., HASHISH, MOHAMED, A.
Applicants: CRAIGEN STEVEN J, FLOW INT CORP, HASHISH MOHAMED A, CRAIGEN, STEVEN, J., FLOW INTERNATIONAL CORPORATION, HASHISH, MOHAMED, A.
Application year: 2000
Main classification: A61B17
IPC codes: A61B17