TURBULENCE MIXING HEAD FOR A TISSUE SEALANT APPLICATOR AND SPRAY HEAD FOR SAME

Abstract: The invention provides a handheld, manually operable fluid applicator, particularly suited to the needs of surgeons, for dispensing a multi-component fluid applicator, for example fibrin and thrombin components of a tissue adhesive. The sealant components undergo turbulent mixing in a mixing chamber (58) to provide effective mixing, and a quality sealant product. The mixing chamber (58) has an increased cross-sectional area over the combined areas of the component supply passages, and the fluid flows are directly opposed to impinge on each other in the mixing chamber (58). The mixing chamber (58) is incorporated in a novel one-piece flexible, and resilient manifold (52). Dual nozzle spray applicators with poppet valves are also disclosed.

Description: TURBULENCE MIXING HEAD FOR A TISSUE SEALANT APPLICATOR AND SPRAY HEAD FOR SAME BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to handheld fluid applicators, wherein an operator operates a fluid dispensing actuator to drive fluid from a reservoir and out of the applicator, through an applicator tip. Such applicators have many different uses and are particularly well suited for dispensing glues and adhesives and indeed are common household items for applying epoxy glues, viscous carpentry glues and caulks and so on. More specialized uses with greater performance requirements, as will be described herein, are for applying tissue adhesives in a surgical context to repair tissue damage, and for equivalent professional, medical, veterinary or biological uses. 2. Description of Related Art Including Information Disclosed under 37 CFR 1.97 and 37 CFR 1.98 Known prior art tissue sealant applicators for multi-component tissue sealant systems generally dispense side-by-side streams of tissue sealant components because of the problems of clogging which are associated with devices that provide internal mixing of the components. Capozzi U. S. Patents Nos. 4,978,336 and 5,1 16,315 and Reidel U. S. Patent No. 5,605,255 teach fibrin sealant spray applicators that internally mix two sealant components immediately before atomizing the fluid flow and discharging it as a spray. Such spray applicators are neither intended for nor capable of dispensing individual drops or droplets or a coherent stream of sealant, as is required to apply a precise or controlled and accurately positioned sealant pattern on a work surface, for example for surgical purposes. Desired such patterns may comprise thin lines, discrete spots and other carefully controlled and placed areas of sealant. Furthermore, such applicators may be subject to clogging between uses, when set down for brief periods of time, and may require replacement of nozzles, tips heads or the like before being re- used. Epstein U.S. patent No. 5,226,877 ("Epstein '877" herein) teaches a sealant applicator that is intended for dispensing individual drops or droplets or a coherent stream of sealant, depending upon the manually applied pressure and duration, and physical characteristics such as the reservoir capacity. The structure of mixing head 10 shown in Figure 1 ofthe accompanying drawings corresponds essentially with Figure 6 A of "Epstein '877". In use, the mixing head 10 is detachably connected to a manually operable applicator enabling a surgeon or other user to controllably dispense dual components of a tissue sealant or adhesive, for example a fibrinogen-thrombin adhesive, through the mixing head 10. Suitable sealants comprise two liquid components that are mixed within the mixing head to provide a coagulatable mixture that clots, forming solid structures, within a time frame that varies depending upon the characteristics of the components, for example, active agent concentration, and other factors. In Figure 1, different reference numerals have been employed, and additions have been made to Figure 6 A of Epstein '877 to show schematically the transit of two colored fluids through the mixing head and their deposit as a pool 12 of mixed liquids on a support surface 14, which is not intended to simulate a work surface but rather is shown as collecting the dispensed mixture for visual inspection. The prior art mixing head 10, as shown in Figure 1, has three fluid passage ports at its rearward end, of which two, ports 16 and 18, when in practical use, are connected to the applicator to receive liquid adhesive components therefrom, while suction is applied to the third, port 20, here shown as located above and between ports 16 and 18. For illustrative purposes, the device has here been shown as admitting a blue fluid to port 16 and a yellow fluid to port 18. Forwardly, the mixing head 10 comprises a suction-in port 22 and a mixed fluid exit port 24. The term "suction" is used herein in the sense ofthe direction of air flow when suction is applied, which will be from the tissue surface, or other application surface, towards a suitable source of suction to which the applicator is connected, in an operating room, or elsewhere. A suction applicator tube 26 and a single mixed adhesive applicator tube 28 are connected respectively to suction-in port 22 and mixed exit port 24. In Epstein '877 it is explained, at column 12 lines 31-38, using different reference numerals, that the suction tube 26 is shorter than adhesive tube 28 so that the suction tube 26 does not interfere visually or functionally with the application ofthe adhesive. Furthermore, the Epstein patent explains that materials from the site of application, when suctioned are brought along the exterior surface of the adhesive channel 28 to the orifice ofthe suction channel 26 and that this action provides gentle, atraumatic suction required in microsurgery. The interior of the mixing head 10 has a Y-shaped channel 30 which connects the two fluid entry ports 16 and 18 with the mixed adhesive exit port 24. Y-shaped channel 30 comprises separate limbs 32, 34 leading from liquid entry ports 16 and 18 respectively, and provides an impingement zone 36 at the base of the Y, where limbs 32 and 34 merge together, which zone 36 connects with exit port 24. ■ A suction channel 38 connects rearward suction port 20 to forward suction-in port 22. As shown by arrows 40 and 42, and in accordance with customary usage, the forward direction is that toward the work surface, or support 14, also known as the distal direction, while the rearward direction is toward the user, or the proximal direction. When pressure is applied by the user, the blue and yellow liquids are moved through ports 16 and 18 into Y-shaped channel 30, where they mix and emerge from applicator 28 in a single stream to be deposited on surface 14, forming pool 12. While the liquids mix, in the sense of becoming combined into a single stream, prior to the present invention, it was not apparent that the stream of liquid emerging from applicator tube 28 might not comprise an intimate mixture or homogenous dispersion of the two liquids. However, it has been discovered, pursuant to the present invention, by separately feeding colored test liquids to ports 16 and 18, for example a blue liquid to port 16 and a yellow liquid to port 18, that the liquids do not in fact mix intimately and the pool 12 of emergent liquid contains identifiable regions of blue or yellow liquid rather than being uniformly colored green as might be expected with effective mixing. Considering the apparent opportunities for commingling in the impingement zone 36, and in applicator tube 28, this result is surprising. Evidently, the configurations of Y-shaped channel 30, including the gentle angle at which the streams of liquid merge, and of applicator tube 28, are such as to provide significant laminar flow so that the two liquids retain at least some spatial separation and do not completely mix. Such incomplete mixing is undesirable, and may reduce the performance ofthe sealant, affecting its time- versus-bonding-strength parameters, performance reproducibility, spatial consistency, or final bond strength. The invention also provides a novel flexible-walled manifold for a sealant applicator which manifold serves to collect fluid components from storage reservoirs and provide an output to one or more dispensing cannulas or tubes. In another aspect, the invention provides a hand held spray applicator of novel construction which generates dual sprays of sealant components which sprays overlap to mix the components. In preferred embodiments, the spray applicators have a unique ergonomic configuration and employ poppet-style control valves that relieve problems of dribble. SUMMARY OF THE INVENTION The invention solves a problem. It solves the problem of providing a fluid applicator mixing head which can provide effective internal mixing of at least two fluid sealant components and is capable of dispensing individual drops or droplets or a coherent stream of sealant. In one aspect, the invention provides a manually actuated sealant applicator for dispensing a mixed output of at least two fluid sealant components capable, when mixed together, of generating a solid sealant product, the applicator comprising a mixing head having: a) a mixing volume for mixing the at least two fluid sealant components; b) at least two fluid sealant component delivery passages each passage connecting with the mixing volume to deliver an individual one of the sealant components separately to the mixing volume with a sealant component input direction; c) a tubular dispensing cannula connecting with the mixing volume to receive a stream of mixed fluid sealant from the mixing volume in a mixed sealant output direction and to dispense the mixed stream at a location displaced away from the mixing volume; wherein the flow of each sealant component through the mixing chamber from the respective delivery passage to the tubular dispensing cannula undergoes a sharp change of direction in the mixing volume, to encourage mixing. Preferably, the sharp change of direction comprises an included angle of at least 45° , preferably, at least 60° and more preferably at least 75° between the sealant component input direction and the mixed sealant output direction. A preferred embodiment employs directly opposed sealant component flows at 180° to one another, each being perpendicular to the output flow. Pursuant to the invention, the sharp change of direction of sealant component flow can be effected by impingement ofthe flow of one sealant component on the flow of at least one other sealant component. Preferably, the mixing volume has a cross-sectional area in the vicinity of the delivery passages being greater than the sum of the cross-sectional areas of the delivery passages said cross-sectional areas being determined transversely to the direction of fluid flow, to facilitate mixing ofthe fluid components. The applicator can also comprises a clearing mechanism to act on residual solid material in the mixing volume to clear the solid material from the mixing volume. In another aspect, the invention provides a mixing head for a sealant applicator which uses impingement flow to enhance mixing wherein multiple adhesive component fluids are discharged into a mixing chamber in directions such as to provide directly opposed flow components in the mixing chamber, e.g. directly opposite to one another, thereby to cause turbulence and active mixing of the adhesive fluid components prior to discharge from the dispenser. Employing a quick setting component adhesive, such for example as the fibrin adhesives used in surgery, curing and resultant setting or viscosity increase may be initiated, or occur, within the dispenser prior to discharge, providing a more viscous flow out ofthe dispenser than would be obtained without apposite mixing. The invention solves the problem of lack of sealant effectiveness which may occur with prior art sealant applicators, which pursuant to the present invention has been discovered to be attributable to delivery to the work site of incompletely mixed tissue sealant components. To this end, the invention provides a 4 mixing head for a tissue sealant applicator which has a zone of turbulent mixing ofthe combined liquid components. The turbulent mixing zone is preferably in a mixing chamber where the individual liquid components are combined into a single stream, but need not necessarily be. The zone of turbulence could for example be created by suitable turbulence-inducing structure downstream ofthe mixing chamber which structure acts on the combined flow inducing turbulence therein and enhance the mixing of the liquid components within the mixing head or applicator. Preferably, the zone of turbulent mixing is created in a mixing chamber by constructing the chamber and fluid supply channels communicating therewith so that there is impingement mixing of the fluid flows in the mixing chamber. By "impingement mixing" is intended that the direction of flow of each fluid into the mixing chamber shall be such that there is substantial opposition of one flow to another so as to cause turbulent mixing. Preferably the interior walls of the mixing volume and dispensing tube that are subject to contact by the mixed sealant are smooth, smoothly contoured surfaces free of structural projections or discontinuities that might attract solid deposits. A potential drawback of such enhanced mixing is that coagulation of the active components may be accelerated, leading to clogging from solids deposited within the mixing head's fluid passageways. To overcome difficulties with clogging, the invention preferably also provides clearing means to remove the deposited solids or to dislodge and remove deposited solids. Such clearing means preferably comprises retrograde suction applied to the combined liquid passageway to withdraw deposited solids, as for example described in the related applications, and if desired, may also include means to dislodge deposited solids to facilitate their withdrawal, or removal by other means, such as will be described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS One way of carrying out the invention is described in detail below with reference to the drawings which illustrate one or more specific embodiments of the invention and in which:- Figure 1 is a partial schematic perspective view of a prior art embodiment of mixing head for a tissue adhesive applicator; Figure 2 is a partial schematic plan view of a first embodiment of mixing head according to the invention, suitable for incorporation in an applicator tip for an applicator intended for dispensing a two-component adhesive system, such as a tissue sealant; Figure 3 is a section on the line 3-3 of Figure 2; Figure 3A is a schematic depiction of a principle of the invention; Figure 3b is a partial schematic plan view of a further embodiment of mixing chamber for a mixing head according to the invention; 5 Figure 4 is a section on the line 3-3 of Figure 2 showing one position of a shuttle valve; Figure 5 is a view similar to Figure 4 showing another position of the shuttle valve; Figure 6 is a view similar to Figure 4, without the shuttle valve, illustrating another embodiment of the invention; Figure 7 is an exploded view of a novel applicator tip for a tissue sealant applicator which comprises a further embodiment of mixing head according to the invention; Figure 8 is an enlarged view of a manifold being a component ofthe applicator tip shown in Figure 7; Figure 9 is an enlarged view of a shuttle valve being a component ofthe applicator tip shown in Figure 7; Figure 10 is an enlarged view of the two halves of a clamshell being a component ofthe applicator tip shown in Figure 7; Figure 1 1 is a partially cutaway view of an assembly of some of the components shown in Figure 7; Figure 12 is a schematic, partial right-hand elevation ofthe clamshell and shuttle valve shown in Figure 7, with a sectional view through a manifold arm, showing a first position ofthe shuttle valve; Figure 13 is a view similar to Figure 12 showing a second position ofthe shuttle valve; Figure 14 is a rear elevation ofthe applicator tip of Figure 7, with components assembled; Figure 15 is a right-hand side elevational view of the assembled applicator tip as shown in Figure 14; Figure 16 is a front elevational view ofthe assembled applicator tip as shown in Figure 14; Figure 17 is a bottom plan view of the assembled applicator tip as shown in Figure 14; Figure 18 is a section on the line 18-18 of Figure 16, with the shuttle valve in a rearward position; Figure 19 is view similar to Figure 18 with the shuttle valve in a forward position; and Figure 20 is a schematic view ofthe simultaneous application of suction and sealant to a tissue surface; Figure 21 is a top plan view of a spray head applicator tip according to another aspect ofthe invention which spray head is attachable to a sealant or other fluid applicator body to dispense multiple sprays of multiple components therefrom; Figure 22 is a side elevational view ofthe spray head shown in Figure 21 ; Figure 23 is a front elevational view of the spray head shown in Figure 21 ; Figure 24 is an exploded perspective view ofthe spray head shown in Figure 21 ; Figure 25 is a right side elevational view of the spray head shown in Figures 21 -24 assembled with an applicator body, showing the assembly in a first position of use; Figure 26 is a plan view on the line 26-26 of Figure 25, showing one possible spray pattern at an intended work surface location; Figure 27 is a view similar to Figure 25 showing the assembly in a second position of use, with its nose extended; Figure 28 is a plan view on the line 28-28 of Figure 27, showing one possible spray pattern, at an intended work surface location, with the extended nose configuration of spray head shown; Figure 29 is a left side elevational view of another embodiment of spray head according to this aspect ofthe invention, cutaway to show, in section, one construction of poppet valve for controlling spray output; Figure 30 is an enlarged view ofthe poppet valve section shown in Figure 29; and Figure 31 is a perspective view of a modified construction of applicator body. DESCRIPTION OF THE PREFERRED EMBODIMENTS The device shown schematically in Figures 2-6 embodies such impingement mixing and solids clearing features ofthe invention. Referring to Figure 2, a mixing head 50 comprises a U-shaped manifold 52, overlain by a generally rectangular shuttle valve 54 and a stop 56. U-shaped manifold 52 (shown in unbroken lines for clarity) has a central mixing chamber 58 and resiliently flexible tubular arms 59 whose walls can be pinched or otherwise pressed together to prevent the flow of liquid therethrough. Arms 59 are constructed and manufactured from a material selected to facilitate such pinching closure, at least in the vicinity of mixing chamber 58. Away from mixing chamber 58, arms 59 terminate in cups 60 that fit over the discharge nozzles of a pair of syringes 62, where tissue sealant components, or other materials, can be accommodated and furnished to mixing chamber 58. Cups 60 are internally fitted with seals 64 which provide a fluid-tight fit with the forward ends of syringes 38. Other, possibly continuous supply, sealant component feed means can be connected to cups 60, as will be apparent to those skilled in the art. The broken lines show an optional third syringe 62 and its accompanying fluid conduits which will be described more fully below. Mixing chamber 58 is generally cylindrical and has a central mixing volume 66 into the sides of which manifold arms 59 open at ports 68. Ports 68 are diametrically opposed to one another, across the mixing volume 66, so that fluids, most probably liquids, fed simultaneously through manifold arms 59 will impinge directly upon each other. Downwardly, mixing volume 66 communicates with a dispensing nozzle, or cannula, 70 through a discharge port 67 into which fluids mixed in chamber 58 are discharged. Upwardly, mixing volume 66 terminates in a clearing port 69 for removal of undesired materials from mixing volume 66 and cannula 70. Preferably, cannula 70 terminates in a discharge aperture 73 and has a tapering structure with a reducing cross-section from mixing chamber 58 to aperture 73 to facilitate retrograde withdrawal of debris by suction. Prior to the present invention, it had been thought necessary that the sealant dispensing cannula should have a substantial length to keep the applicator and the user's hand well clear ofthe work surface at the site of application, for example, referencing a hand-held applicator having a length ofthe order of six inches (15 cm), a projecting length outside the applicator tip of about 1.5 or 2 (3.8 or 5) or more inches. However, pursuant to the present invention, it has now been discovered that the length of the mixed sealant conduit from mixing volume 66, at the point where the sealant components become mixed, to the point of discharge from the applicator should be as short as practicable to prevent clogging. Furthermore, it has surprisingly been found unnecessary to maintain substantial spacing between cannula 70's discharge aperture 73 and the user's hand (or cannula embracing finger), so that a short cannula, for example, projecting less than 1 inch (2.5 cm), preferably less than about 0.8 inches (1cm) from the applicator body, can be used and is advantageous in enabling mixed fluids to be rapidly discharged from the applicator. Toward the end of minimizing the the length ofthe mixed liquid pathway from point of mixing to point of exit from the device, it is desirable to locate mixing volume 66 closely to any external housing ofthe mixing head, for example as is achieved with the embodiment of applicator tip illustrated in Figures 7-19, notwithstanding the relative complexity ofthe internal components ofthe applicator tip depicted. Preferably also, mixing volume 66 has a cross-sectional area in excess ofthe sum ofthe areas of arms 59 to provide an air volume to facilitate mixing, at least at the beginning ofthe applicator stroke wherein sealant components are driven from syringes 62 through arms 59 to an otherwise empty mixing chamber 66. By employing an area for aperture 73 that is less than the combined cross-sectional areas of tubular arms 59 it is possible to build back pressure in cannula 70, and in mixing volume 66, which, combined with the free space therein and with the opposed positioning ofthe fluid streams as they are admitted to mixing volume 66, is helpful in promoting turbulent mixing and avoiding stratification ofthe fluid components in the dispensed fluid stream. The schematic view of Figure 3 illustrates the mixing principles ofthe invention as they apply to the mixing of sealant components, comprising fibrinogen and thrombin respectively, which are thoroughly mixed to provide an effective tissue sealant that is readily applied to a suction- prepared tissue surface. Now thoroughly mixed, as they leave mixing chamber 66 and advance along cannula 70, the sealant components will begin to interact and cure. Accordingly, the length of cannula 70 should be selected according to the setup time ofthe sealant, taking into account the rate of transit of sealant mixture through cannula 70 to avoid clogging cannula 70. Cannula 70 can be provided in various lengths according to the particular purpose for which the applicator is to be employed so that where a short setup sealant is employed, for example a fibrin sealant using a thrombin component with an activity of the order of 100 IU, a particularly short cannula may be employed, whereas for a sealant with a longer setup time for example one provided with a thrombin component having a low activity of the order of 5 IU, a longer cannula 70 can be used. Prior to the present invention, it had been thought necessary that the sealant dispensing cannula should have a substantial length to keep the applicator and the user's hand well clear ofthe work surface at the site of application, for example, referencing a hand-held applicator having a length ofthe order of six inches (15 cm), a projecting length outside the applicator tip of about 1.5 or 2 (3.8 or 5) or more inches. However, pursuant to the present invention, it has now been discovered that the length ofthe mixed sealant conduit from mixing volume 66, at the point where the sealant components become mixed, to the point of discharge from the applicator should be as short as practicable to prevent clogging. Furthermore, it has surprisingly been found unnecessary to maintain substantial spacing between cannula 70's discharge aperture 73 and the user's hand (or cannula embracing finger), so that a short cannula, for example, projecting less than 1 inch (2.5 cm), preferably less than about 0.8 inches (1cm) from the applicator body, can be used and is advantageous in enabling mixed fluids to be rapidly discharged from the applicator. Toward the end of minimizing the mixed liquid pathway from point of mixing to point of exit from the device, it is desirable to locate mixing volume 66 closely to any external housing ofthe mixing head, for example as is achieved with the embodiment of applicator tip illustrated in Figures 7-19, notwithstanding the relative complexity ofthe internal components of the applicator tip depicted. One or more flanges, such as circumferential flange 71, or other suitable structure, can be provided to enable cannula 70 to be located and held in mating engagement with mixing chamber 58 by suitable support structure (not shown). Cannula 70 and mixing chamber 58 are canted downwardly and forwardly to facilitate application ofthe sealant, or other mixture of working fluids. Upwardly, mixing chamber 58 is slidingly engaged by shuttle valve 54 which rides on chamber 58 to control admission of suction thereto. Stops 56 are located adjacent arms 59, as close as is practical to mixing chamber 58. Shuttle valve 54 comprises a rectangular body 72, from the rearward end of which extend elongated actuator members 74 having cam surfaces, the details of which are not here shown, but which can be used to drive the shuttle valve 54 back and forth in a forward then a rearward direction. Shuttle valve 54 has a central opening 76 to communicate with mixing volume 66 when the valve is in a forwardly advanced position, as shown in Figure 5. When not forwardly advanced, shuttle valve 54 seals off the upper side of mixing volume 66. Clamping blades 78 depend downwardly from valve body 72 and cooperate with stops 56 on each side of mixing chamber 58 to clamp each manifold arm 59 individually between a clamping blade 78 and a stop 56 thereby to close the arm 59 against the flow of liquid as the shuttle valve 54 advances to its forward position. The described components can all be manufactured from a suitable injection-moldable polymeric or plastics material, or the like, as will be known to those skilled in the art, provided that manifold arms 59 are sufficiently deformable and resilient to make a good closing seal when firmly clamped between clamping blade 78 and stop 56. Preferably, mixing chamber 58 has at least some limited resilient deformability, whereby the clamping of manifold arms 59, closely adjacent to mixing chamber 58, acts upon deposited solids in or near mixing chamber 58 to dislodge them facilitating their removal from the mixing head. Liquid in manifold arms 59 acts hydraulically in response to the squeezing pressure of clamping blades 78. Such resilient deformability, as a characteristic of the material of manifold 52, is beneficial not only to permit proper closure, sealing and resilient re-opening of tubular arms 59 when engaged by clamping blades 78, but also as a characteristic of seals 64, to enhance their effectiveness, of the mixing chamber 58 to facilitate dislodgement of undesired solid deposits and to facilitate sealing engagement of mixing chamber 58 with shuttle valve 54 and dispensing cannula 70. If suction is employed, (as it is in the preferred embodiments herein) to prepare, clean-up or manipulate the work surface, and it is desired to apply suction simultaneously with the tissue sealant, then suction can be applied through central opening 76, connecting with a suction conduit having an aspiration nozzle, or second cannula, terminating in an output aperture adjacent to that of dispensing cannula 70. Such suction- applying structure is not shown here, but an embodiment thereof is described in more detail below in connection with Figures 7-20, and suitable implementations thereof, depicting a complete suction conduit from source to the surface are also described in the related applications. It will be understood that such applications also describe and disclose suitable embodiments of manually powered drive mechanisms and operating controls permitting delivery of sealant components and application of suction, as desired pursuant to the invention. Suction clearing of any solids coagulating in the mixed liquid pathway is assisted by avoiding tortuous configurations ofthe mixed liquid pathway, by providing reducing cross-sectional area in the downstream direction, and by providing the mixed liquid pathway with smooth walls, preferably fabricated of a non- sticking material. In use, an operator urges a manual actuator to drive sealant components through syringes 62 into manifold 52 where the components travel along arms 59 and emerge from ports 68 into mixing volume 66. As shown in Figure 3, the alignment of ports 68 and arms 59 is selected so that the jets emerging from arms 59 into mixing volume 66 impinge directly upon one another, creating a zone of substantial turbulence in mixing volume 66 where the liquids are brought into intimate contact with one another and thus become thoroughly mixed. Such head-on impingement ofthe flows is effective to divert kinetic energy to cause 10 mixing. While a diametrically aligned opposition of the two liquid flows is preferential for more effective mixing, useful, albeit inferior mixing, can be obtained employing different alignments, for example with an included angle between the directions of flow at the point of mixing no less than 120°, preferably no less than 150°, rather than the preferred 180°, provided that substantial laminar flow through dispensing cannula 70 is prevented. The efficacy of mixing, and thence the acceptability of any particular structural variation, can be determined by means of a simple test such as the use of blue and yellow colored liquid components, as described in connection with the prior art device shown in Figure 1. A uniformly green product should be consistently dispensed from dispensing cannula 70. A suction control valve is coupled with shuttle valve 54 whereby actuation ofthe suction control valve by the operator moves shuttle valve 54 forwardly from the position shown in Figure 4 until central opening 76 registers with mixing volume 66, as shown in Figure 5. The applied suction clears mixing volume 66 and dispensing cannula 70 of residual mixed sealant components, deposited solids and other debris. As shuttle valve 54 approaches the suction registration position of Figure 5, clamping blades 78 engage resilient manifold arms 59 closely adjacent mixing chamber 68, compressing the arms 59 against stops 56 and closing them provide flow of flow of liquid sealant component therethrough. At the same time residual solids or debris adjacent ports 68 may be dislodged, squeezed or otherwise forced away from ports 68 into the upward suction stream in mixing volume 66, to be withdrawn from the device. Preferably, the suction control valve and shuttle valve 54 are biased to return to the position shown in Figures 2 and 4, for example by being spring-loaded, enabling an operator to release the suction control and re-commence application of sealant. Such suction clearing means provides a simple and easy method of clearing the mixed liquid conduit. An alternative construction of clearing means is shown in Figure 6 which illustrates a modified dispensing cannula 75 which extends upwardly into mixing volume 66 where it has a sleeve portion 80 which is a close fit in mixing volume 66, providing a liner for mixing chamber 68. Openings are provided in sleeve portion 18 in registration with ports 68 to admit liquid components into mixing volume 66. Sleeve portion 80 of dispensing cannula 75 can be a press fit or snap fit in mixing volume 66 or otherwise can be releasably secured to mixing chamber 58 or to housing structure that effectively locates sleeve portion 80 in mixing volume 66. The modfied cannula 75 shown can be disposable, (although there are drawbacks associated with using disposable components with fast curing sealants, which are described below), but is also useful where the sealant components has a short setup time and clogging problems occur that are not resolved by the use of suction clearing. Also, cannula 75 can assist in dislodgement of any solid deposits in the vicinity of ports 68, when it is removed as its sleeve portion 80 11 exerts a mechanical disrupting action on any such deposits. Such a dispensing cannula can be embodied in disposable form being readily removed, discarded and replaced with a new cannula at desired intervals, for example for each new patient, or procedure. Clogging resulting from the deposit of solids generated by reaction ofthe sealant components with one another and thus will only manifest itself as a problem in locations within the mixing head where the sealant components contact one another. Effectively this should be only at ports 68 and points downstream thereof. Accordingly, use of such a cannula can eliminate the need for suction to clear the mixed fluid conduits that are subject to clogging, as any contaminating debris in the conduit will be removed with the cannula and discarded. This capability may be valuable where suction is not readily available, for example in field conditions. However, one drawback to disposability is that sealant components are lost, and being valuable, wiht 1998 costs ofthe order of $100 per ml in the United States, such losses significant. Furthermore cannula or cannula-and-liner disposability is not an effective solution to clogging problems with a fast curing sealantwhich may clog in less than a minute during between the steps of a given procedure. An unrelated benefit of cannula 75 is to provide a unique, non-adhesive surface material differing from the material ofthe individual fluid conduits, for example polytetrafluoroethylene for those fluid conduits that are exposed to mixed sealant. If desired, disposable embodiments of dispensing cannula 70 can contain turbulence-creating structure such as fins, baffles or protrusions that so direct the liquids in the mixing volume or in the tubular cannula portion as to enhance turbulence and thence improve the mixing ofthe two or more liquid sealant components. Such a removable cannula 70 can be economically fabricated as an inexpensive plastic molding and constitutes a simple and effective clearing means. While use of a removable cannula which effectively contains the complete mixed fluids conduit from a zone of mixing to the point of egress from the mixing head, can eliminate need for retrograde suction or other clearing means, if desired, suction clearing can also be used, either to clear the disposable cannula during use, or to clear mixing volume 66 with dispensing cannula 70 removed, or both. Figure 6 illustrates how mixing chamber 58 can be modified by closing off the upward side of mixing volume 66. Shuttle valve 54 can also be simplified, if suction clearing is not employed, being constructed simply to operate clamping blades 78. However, the value of suction for preparing the tissue surface and for removing excess adhesive calls for its use in many applications, so that suction will usually be readily available for the described clearing functions ofthe invention and its use is desirable. 12 The third syringe 62A, shown in broken lines in Figure 2, can be positioned between, or beneath and between, the two syringes 62 and, as indicated, manifold 52 can be provided with a third arm 59A and cup 60A to communicate with syringe 62A. Such is preferably operated in harness with syringes 62 to deliver liquid therefrom simultaneously with the delivery of fluids from syringes 62. However, third syringe 62A may have a different geometry, to provide a different flow rate, if desired. Third syringe 62A can accommodate, or provide, a third sealant component or an additive useful at the work site, for example a therapeutic composition. Preferably, the dispositions of port 68 A and arm 59A are such that the liquid flow from syringe 62A into mixing volume 66 is opposite to the flows of one or both ofthe liquid components from syringes 62, whereby mixing of all three components is facilitated or enhanced. For example, the three flows may be directed to a common point of convergence, as shown in Figure 7. The efficacy of mixing of 3 sealant components can also be determined using colored liquids. However, rather than trying to select three different colors that will mix to produce a suitably indicative end product, it is preferred again to use blue and yellow liquids, with a clear liquid in the third syringe 62 or 62 A and perform the test three times, rotating the colors between the syringes to show satisfactory mixing in pairs. If every pair mixes well, it is reasonable to assume that all three liquids will blend well. If one or more liquids has significant viscosity, the test liquid should be made comparably viscous, e.g. by using a transparent thickening agent such as carbopol or agar. The tissue sealant applicator tip embodiment incorporating a mixing head shown in Figures 7 -19 is a more detailed embodiment ofthe invention which embodiment includes most ofthe features shown in the embodiment of Figures 2-6 and is suitable for manufacturing from injection molded plastics components. As will be described, several ofthe parts ofthe mixing head shown in Figures 7-19 embodying similar construction and functionality to the components ofthe embodiment of shown in Figures 2-6. Many individual structural features ofthe components ofthe applicator tip can be seen from the exploded view of Figure 7, while Figures 8-14 and 18-19 show additional structural features and relationships of the internal components and Figures 14-17 show the overall external appearance of the applicator tip. Referring to Figure 7, the mixing head 100, there shown in exploded view, comprises a U-shaped manifold 102, embodying features of manifold 52, a shuttle valve 104, embodying features of shuttle valve 54 and a dispensing cannula 106 embodying features of dispensing cannula 70. Additionally, mixing head 150 comprises an inner clamshell 108which supports manifold 102, shuttle valve 104 and dispensing cannula 106 in assembled configuration, and an aspiration cannula 1 10 which is similarly supported in assembled configuration with the foregoing parts by clamshell 108 where it connects with the suction conduit through the mixing head 150 and the applicator. Clamshell 108 has a left-hand half designated 108 LH and a right hand half designated 108 RH. The numeral "108" is used to reference the 13 two halves conjointly. In prefeired embodiments, shuttle valve 104, dispensing cannula 106, aspiration cannula 110, clamshell 108, connecting plate 1 12 and an attractively styled tip housing 1 18 are essentially rigid, injection-molded components having limited resilience in their thinner sections. In contrast, manifold 102 is preferably fabricated from a distinctly elastomeric, resilient molding material so that, in a relaxed state, the tubular arms of manifold 102 unfold and extend in a straight line. Manifold 102 is preferably also transparent as are other liquid-contacting components, to permit limited inspection ofthe liquid conduits through the mixing head. A suitable material for manifold 102 is a silicone rubber, for example silicone rubber supplied under the trademark SILASTIC (Dow Corning Corporation) or the trademark BAYSILONE (Bayer A.G.). Other liquid contacting components are preferably fabricated of a relatively more rigid polymeric plastics material such as polypropylene, or polytetrafluoroethylene, with smooth interior surfaces to resist adhesion by deposits or clogs of fibrin material. Connecting plate 112 mates with the assembled manifold 102 shuttle valve 104 and clamshell 108 and is provided with suitable structure on its rearward face to connect with an applicator body. A tension spring 114 connected to a bifurcated retainer block 116 on one side of connecting plate 112 and to the shuttle valve 104 on the other side of connecting plate 112 biases shuttle valve 104 in the rearward direction. An attractively styled tip housing 118 completes the mixing head assembly, fitting over manifold 102, clamshell 108 and shuttle valve 104 and snap fitting with connecting plate 1 12 to form an integral assembly from which dispensing cannula 106 and aspirator cannula 110 depend downwardly and forwardly toward a work surface. Connecting plate 1 12 comprises a pair of forwardly extending sleeves 120 which are received over the forward ends of liquid component feed syringes such as syringes 62 (Figures 2-6), and above which are located a pair of S-shaped compression latches 122 having manually depressible ribbed outer tab portions 124. Tip housing 118 has cutouts 126 (one shown in Figure 7) to accommodate latches 122 and is internally configured to be a snap fit over mounting plate 112, with the remaining components ofthe applicator tip mounted thereon (see Figure 18). Rearwardly, connecting plate 112 has a pair of flanged guide pegs 119 to stabilize the attachment ofthe applicator tip to an applicator body. Inner portions 128 of latches 122 provide resilience and enable guide pegs 1 19 to be securely engaged in an applicator body by a user compressing tabs 126 together with their thumb and forefinger. Centrally, connecting plate 112 has an aperture 130 configured to receive and locate the forward end of clamshell 108. On its rearward surface connecting plate 1 12 is configured to receive and locate spring 14 retainer 1 16. Manifold 102 comprises a central mixing chamber 132 from which extend tubular arms 134, which arms terminate in cylindrical cups 136, which cups 136 fit snugly within sleeves 122 of connecting plate 1 12 where they are located by external colors 138. Cups 136 are internally configured to be pressed into tight sealing engagement, when so mounted within sleeves 122, with the forward ends of sealant component syringes mounted in a mating applicator body, to receive liquid components therefrom. The interfitting relationship between cups 136 and sleeves 122 is indicated by broken lines 140. Tubular arms 134 of manifold 102 are flexible and can readily be manipulated during assembly ofthe mixing head 100, to be turned from an unassembled, relaxed state, straight line configuration, as shown in Figure 8, through 90 degrees to align each cup 136 with the syringes in the applicator body, along the rearward-forward direction shown, while the inward ends of arms 134 maintain an opposed alignment at the mixing chamber 132 to effect impingement, turbulent mixing of liquids conveyed through the arms 134. A cross-section through mixing chamber 132 and arms 134 is essentially similar to Figure 3. Mixing volume 148 opens downwardly to a sealant discharge opening 149 which communicates with cannula 70, and upwardly to port 151 which communicates with a suction clearing conduit, to be described. The flexibility of tubular arms 134 simplifies manufacure and provides considerable freedom of movement ofthe outward ends of cups 136, which facilitates assembly of mixing head 100, accommodates tolerances in other components and can also accommodate minor design variations in other components that may be required from time to time. Molding ofthe in-line relaxed state configuration (Figure 8, broken lines) is considerably easier than would be the U-shaped assembled configuration which might have to be molded in two halves. Mixing chamber 132 has a frusto-cylindrical shape with an upper surface 142 which is approximately horizontally disposed and bears a unitary upstanding sealing ring 144 which makes a substantially airtight seal with shuttle valve 104. Under surface 146 of mixing chamber 134 is perpendicular to the direction of extent of dispensing cannula 106 and enters into sealing engagement therewith for which purpose under surface 146 could be provided with a seal similar to seal 144, if desired. Internal passages in manifold 102 are shown in broken lines and provide a mixing volume 148 similar to mixing volume 66, Figure 2. Other minor structural features such as abutments will be apparent from the drawings, or can be added by those skilled in the art. While manifold 102 could be integrally constructed from a number of components, preferably and advantageously , it is a unitary structure. By incorporating a number of components into a single element, capable of injection molding fabrication, considerable economy of manufacture and reliability of operation is obtained. Of significant value is the fact that one element, 15 manifold 102, provides multiple resilient seals for fluid tight engagement with four other components, namely two syringes, shuttle valve 104 and dispensing cannula 106. Seals that would otherwise be required if mixing chamber 132 and arms 134 were separate components are also eliminated. Manifold 102 also constitutes a useful service component that can readily be replaced. Shuttle valve 104 comprises a generally rectangular body 150 having a central opening 152 and a small rearward opening 154 which is engaged by forward end of tension spring 1 14, as indicated by broken line 155. Spring 1 14, anchored by retainer block 116 engaging clamping plate 1 12, biases shuttle valve 104 rearwardly, causing valve 104 to return to its sealant dispensing position after it has been forwardly advanced to effect suction clearing of mixing volume 148 and dispensing cannula 106. Clamping blades 156 depend downwardly from the forward end of body 150, have a partially rectangular shape with their lowermost forward corners cut back to provide an inclined surface 158 to engage tubular arms 134 of manifold 102 closely adjacent mixing chamber 132, as shown in Figures 1 1-13. Elongated actuator members 160 extend rearwardly from rectangular body 150 and terminate in upstanding buttresses 162 which present upward facing cam surfaces 164 for engagment by manual actuation ofthe suction valve (not shown). Intermediately their lengths, actuator members 160 have guide portions 166 which engage and are guided by outer surfaces of clamshell 108. Referring to clamshell 108, as shown in Figure 10, it will be appreciated that the structural elements described are, for the most part, provided conjointly by structure from both halves only clamshell 108 LH and 108 RH. Thus, clamshell 108 comprises a suction aspiration conduit 168 in the lower half of the clamshell and a suction clearing conduit 170 in the upper half of the clamshell. Suction aspiration conduit 168 communicates with the suction valve (in the applicator body, not shown) and terminates in a port 169 which receives aspiration cannula 110, while suction clearing conduit 170 communicates suction from the suction valve to mixing chamber 148 and thence to dispensing cannula 106. Intermediately of suction conduits 168 and 170, a short tubular opening 172 is provided to accommodate spring 1 14. The rearward end of clamshell 108 comprises a shroud 174 configured to be received through connecting plate 1 12 and to present aspiration and clearing suction ports 176 and 178 respectively for to communicate with the applicator's suction valve. Ribs 180 locate clamshell 108 against receiving structure 182 in mounting plate 1 12. Externally, shroud 174 has a pair of right-section recesses 184 which engage with guide portions 166 of shuttle valve 104, positioning the valve as it moves back and forth. Centrally, clamshell 108 is formed with a horizontally disposed rectangular box portion 186 which accommodates rectangular body 150 of shuttle valve 104 for sliding movement therein. Laterally of box portion 186, each half of clamshell 108 is formed with an opening 188, configured with an arcuate rest 190 to accommodate a respective tubular 16 resilient arm 134 of manifold 102 and shaped to permit a respective clamping blade 156, depending from forward portion of body 150 of shuttle valve 104, to engage the arm 134 pinching its walls together against rest 190 and preventing fluid flow therethrough. Box portion 186 has an end wall 192 which extends across the full width of shuttle valve 104 and is engaged by an end face 194 on shuttle valve 104 to provide a positive limit to forward movement ofthe shuttle valve. The geometry is selected such that this limit is reached at a point which protects tubular arms 134 from undue compression, yet permits effective closure of the arms by clamping blades 156 to stop fluid flow therethrough. A hook-like structure at the forward end of clamshell 108 has an opening 196 which receives and supports dispensing cannula 106, and laterally thereof has extensions 198 that support arcuate seats 190 for manifold arms 134. When its two halves 108LH and 108RH are assembled together, using one or more press fit studs such as 200, and as indicated by broken line 201 , clamshell 108 is designed to be a sturdy component which supports and holds shuttle valve 104 and manifold 102 together with cannulas 106 and 1 10 in a proper working relationship for assembly to connecting plate 1 12. Broken line 202 indicates the assembly point of cannulae 106 and 108 with clamshell 108. Spring 114 holds these components in place in relation to clamping plate 112 while tip housing 118 is internally configured so that when it is snap fitted to connecting plate 1 12 all components are properly located and securely held in position (Figures 18-19). Referring to Figures 1 1-13, when manifold 102 is assembled with clamshell 108, it is precisely located therein with manifold arms 134 supported on arcuate rests 190 and extending outwardly through openings 188 to be folded rearwardly for engagement over syringes such as 62 when the applicator tip is attached to an applicator body. Shuttle valve 104 is free shuttle back and forth with its body 150 and depending clamping blades 156 located substantially within the clamshell 108, subject to the to the rearward biasing action of spring 1 14. In Figure 1 1, shuttle valve 104 is shown retracted somewhat rearwardly from its normal rearward position to expose the structure ofthe top of mixing chamber 132 and seal 144. In the normal rearward position of shuttle valve 104, Figure 18, body portion 150 overlies the top of mixing chamber 132 and makes an air-tight seal with seal 144, preventing upward discharge of sealant fluids. It is of course desirable to avoid contamination ofthe underside of shuttle valve body 150 with sealant fluids which might result in shuttle valve 104 seizing up and jamming the applicator. To this end, mixing chamber 132 has a significant extent above arms 134 to reduce the probability that back splash within chamber 132 will strike body 150 and provide an air cushion to deter such contamination and help 17 smooth the output of sealant from dispensing cannula 106. A further function of resilient seal 144 is to wipe the under surface of body 150 to remove any liquid or solid deposits therefrom, which can then be aspirated from mixing volume 148, in suction clearing mode. Referring to Figures 12-13, -n Figure 12 shuttle valve 104 has begun its forward movement in response to user actuation ofthe suction valve and inclined surface 158 of clamping blade 156 is tangentially engaging an upper surface of tubular arm 134. As shuttle valve 104 advances into the fully forward position of Figure 13, tubular arm 134 is progressively compressed in a controlled and graduated manner until end face 194 of valve 104 engages end wall 192 of clamshell 108. At this point tubular arm 134 is closed to the passage of fluid therethrough but, by proper choice ofthe geometry is not unduly stressed. Rather than being absorbed as a crushing force on tubular arm 134, any excess closing load is applied directly to end wall 192 and the load is spread over a much more substantial area that is provided by a blade 156 engaging, 134. As described hereinabove, the geometry is also preferably selected so that blades 156 engage arms 134 closely beside mixing chamber 132 to help dislodge any clogging solids that congregate in the vicinity of mixing chamber 132's inflow ports. Dislodging forces are transmitted hydraulically from the point of closure of tubular arms 134 through the sealant component liquid in the arm to the obstruction, if present, as each arm is squeezed by clamping blade 156. Dispensing cannula 106 comprises an upper cup-shaped portion 204 which fits closely around the mixing chamber 132 and has side slots 206 to accommodate arms 134. As stated above, cannula 106 is constructed of a relatively rigid material so that cup portion 204 can locate and position the cannula in clamshell 108 and also support and locate mixing chamber 132 within clamshell 108. Such support is needed to provide dimensional stability, noting that manifold 102 is formed of a relatively resilient material. Downwardly of cup portion 204 cannula 106 is provided with an alignment bar 208 extending along a significant portion ofthe length ofthe cannula, below which the cannula terminates in a dispensing aperture 210. Cannula 106 has an internal flow path which decreases in cross-sectional area toward aperture 210, as will be described in more detail in connection with Figures 18 and 19. Cannula 1 10 has a collar 212 at its upper end which press fits on to suction clearing conduit port 169 and engages tightly therewith. Collar 212 has a projecting flange 214 that engages and supports cup-shape portion 204 of cannula 106. Aspiration cannula 1 10 terminates in an aspiration aperture 216 and intermediate its length has a set of claw-like projections 218 to engage and cooperate with alignment bar 208 to provide suitable relative positioning of cannulas 106 and 110. 18 As best shown in Figures 14-17, tip housing 126, tip housing 1 18 neatly accommodates the assembly of clamshell 108, shuttle valve 104, manifold 102 and connecting plate 1 12 .with cannulas 106 and 110 projecting from the housing 118 through openings 220 and 222. Tip housing 1 18 is attractively and aesthetically styled and provides a convenient, ergonomically designed device which can be readily assembled with a sealant applicator such as is disclosed in the applications and when assembled therewith can be precisely and dextrously manipulated to apply suction and sealant to tissue surfaces, for example to perform, or in the course of performance, of a surgical operation. In a preferred embodiment, the complete applicator, with an applicator tip as shown, can comfortably be held between the forefinger, index finger and thumb, much like a writing instrument enabling a user to take advantage of their natural precision motor actions developed for writing or drawing, to dispense sealant skillfully. Connecting plate 112 comprises a pair of forwardly extending sleeves 120 which are received over the forward ends of liquid component feed syringes such as syringes 62 (Figures 2-6), and above which are located a pair of S-shaped compression latches 122 having manually depressible ribbed outer tab portions 124. Tip housing 118 has cutouts 126 (one shown in Figure 7) to accommodate latches 122 and is internally configured to be a snap fit over mounting plate 112, with the remaining components ofthe applicator tip mounted thereon (see Figure 18). Rearwardly, connecting plate 112 has a pair of flanged guide pegs 1 19 to stabilize the attachment ofthe applicator tip to an applicator body. Inner portions 128 of latches 122 provide resilience and enable guide pegs 1 19 to be securely engaged in an applicator body by a user compressing tabs 126 together with their thumb and forefinger. Figures 18-19 show clearly the respective rearward and forward positions of shuttle valve 104. In Figure 18 body portion 150 of shuttle valve 104 closes the upper side of mixing volume 148 and the buttress portions 162 ofthe valve can be seen projecting rearwardly from plate 1 12, while in Figure 19 shuttle valve 104 has moved forwardly, bringing opening 152 into registration with mixing volume 148 to apply suction to clear the mixing volume and cannula 106 (arms 134 being closed by clamping blades 156). The extension of return spring 114 may also be seen in Figure 19. The internal configurations of cannula 106 and mixing volume 148, which provide the mixed fluids exit pathway from the applicator tip and which open rearwardly into conduit 170, to provide a suction pathway for retrograde clearing ofthe cannula, can best be seen by referring to Figures 18, and 19. The interior 19 walls of cannula 106 and mixing volume 148 preferably smooth, polished and formed of a material resistant to adhesion, for example, cannula 106 can be formed of a highly polished rigid polypropylene or polytetrafluoroethylene. To reduce the probability of clogging, the length L of cannula 106 is kept as short as is practicable and is consistent with ergonomic and surgical requirements. Thus, referring to the case of a hand-held applicator intended for dispensing tissue sealant, cannula 106 should project a sufficient distance from tip housing 118 to allow the housing tip 1 18 to be properly gripped by the user's fingers or fingers and thumb, while still providing a working length of cannula 106 with which to address tissue surfaces of various configurations and accessibility. A suitable value of L, consistent with efficient manipulation ofthe applicator in the manner described below, lies within the range of from about 0.6 to about 1.2 inches (1.5 to 3 cm), preferably about 0.75 inches ( close to 2 cm). Tip housing 118 is designed to facilitate support ofthe applicator in a user's hand while gripping and manipulating cannulas 106 and 110, which are effectively rigidly interconnected by bar 208 and projections 218. For this purpose, tip housing 118 has features such as a convergent nose portion 228, with a downwardly inclined, laterally curved upper face 230 which can be held under a user's forefinger, and a small flattened underface 231 which can rest on a user's index finger. Coupled with the forward location of openings 220 and 222, these features enable the complete applicator to be readily gripped like a pen, or other writing or drawing instrument, by supporting the housing tip 1 18 on the index finger with cannulas 106 and 1 10 projecting over and resting on the index finger while the forefinger extends across the top ofthe applicator gripping surface 230 to provide control while the body ofthe applicator extends between the thumb and forefinger and the thumb is left free tooperate necessary controls such as a fluid dispensing control and a suction control ergonomically located on top ofthe applicator, for example, as shown in the applications. Thus held, the complete applicator (see the applications) can extend across the side ofthe hand with a suction supply line draped across one side ofthe hand or the other and has a surprisingly well-balanced feel so that it is comfortable and convenient to use and can be operated with precision. Other ways of manipulating the applicator will be apparent to those skilled in the art. As previously discussed, it is desirable to provide rapid mixing and a short mixed fluids pathway out of the applicator, to prevent clogging, or undue viscosity build-up. As shown, cannula 106's internal fluid passage, here designated 224, tapers toward dispensing aperture 210, while mixing chamber 132 is disposed closely adjacent to tip housing 118 to shorten the length ofthe mixed fluids pathway which can be defined to begin at fluid admission port 226 where manifold arm 134 (not visible in Figures 18-19) opens into mixing chamber 148. The relative dimensions ofthe several fluid conduits that lead into and 20 comprise the mixed fluid pathway can be selected to enhance rapid mixing and rapid discharge ofthe mixed sealant components. Refeiring to the cross-sectional areas ofthe various conduits and ports, (which will determine the fluid flow rate for a given drive pressure and fluid viscosity), the cross-sectional area of mixing volume 148 substantially exceeds the combined areas of arms 134 at ports 226, being, for example, at least twice as large, or preferably three or more times as large as the port areas, to provide, at least at the beginning of a fluid dispensing stroke, free space in mixing volume 148 for hydraulic-pneumatic turbulent mixing ofthe incoming fluid sealant components. Cannula 106's internal passage area 224, at its upstream end, is somewhat less than that of mixing volume 148, to ensure that no obstruction to retrograde suctional clearing can occur at the boundary between the two, yet, preferably also substantially exceeds the combined port areas. Passage 148 tapers downwardly to aperture 216, where it has an area which is preferably less than the combined areas of ports 168, being for example comparable with that of a single port 168, to provide back pressure to promote continued turbulent mixing in mixing volume 148 and the upper end of cannula 106. As may further best be seen in Figures 18-19, tip housing 118 has an internal lip 234 at its lower periphery which latches in a mating recess 236 in the lower periphery of connecting plate 1 12. Tip housing 118 may be assembled with the remaining applicator tip components, after they have been assembled with connecting plate 112, by passing cannulas 106, 110 through openings 220, 222, latching lip 234 into recess 236 and snapping the top ofthe tip housing over the top ofthe connecting plate. The applicator tip described with reference to Figures 7-19 can readily be assembled with an applicator body, gripped, manipulated and manually actuated to dispense desired patterns of thoroughly mixed adhesive with sufficient accuracy for many surgical purposes, including drops or spot patterns, droplets, beads and continuous line patterns. As shown in Figure 20, the positioning, disposition and proximity of suction aperture 216 permits tissue 240 to be cleaned of fluids 242, or other debris, and dried prior to application of sealant 244 by drawing the applicator toward the user, while also removing any excess sealant that comes within range of suction aperture 216. A suitable applicator body for assembly with the droplet applicator tip illustrated in Figures 6-19 is shown in Figures 25 and 27 with a spray head attached, the spray head shown comprising an embodiment of a further invention herein. In a preferred embodiment, the droplet applicator tip, an extended reach version thereof, for example as shown in the related applications, and a spray head such as that shown in Figures 21-30, described below, are interchangeably fittable (by the user) not only to the barrel style of applicator shown, but also to a pistol grip applicator such as shown in the related applications. 21 Comparative tests were conducted to compare the performance of a fibrin sealant applicator according to the invention employing a droplet head with impingement mixing substantially as described with reference to Figures 7-19, "the inventive applicator" with two commercially available applicators, namely an applicator sold under the trademark DUOFLO by Haemedics Corp. and an applicator sold under the trademark FIBRIJECT by Micromedics Corp. Two fibrin sealant components were used namely a bovine- sourced cryoprecipitate, BioSurgical Corp., fibrin sealant component 1, and topical thrombin in 40 mM CaCl 2 fibrin sealant component 2, JMI, Inc. Test subjects were rabbits, the kidneys and spleen of each of which were exposed and incisions of controlled length and depth were made. Fibrin sealant was then applied by one of three sealant applicators. The time to hemostasis was recorded. The following procedures were used: Kidneys 1. Expose the left kidney via a midline abdominal incision. 2. Carefully dissect kidney free from any adherent tissue or fat. 3. Elevate kidney and place gauze underneath, spreading out to isolate organ from surronding anatomic features. 4. Clamp a hemostat to a #10 scalpel blade so that 3 mm ofthe tip is exposed. 5. Place a scale longitudinally along the upper lateral edge ofthe kidney and make an incision 20 mm long. 6. Once bleeding has begun, lightly dab incision with gauze and immediately apply fibrin sealant with test applicator. 7. Record time until essentially all bleeding has ceased (slight oozing). Continue to record time until complete hemostasis occurs. Discontinue all time measurements after 10 minutes is still bleeding. 8. Repeat steps 5 through 7 for the lower lateral edge ofthe left kidney. 9. Steps 5 through 7 may be repeated for the ventral side ofthe kidney if more data points are needed. 10. Repeat steps 2 through 7 for the right kidney. Spleen 1. Expose the spleen via the same midline excision made for the kidneys 2. Carefully dissect spleen free from any adherent tissue or fat. 3. Elevate spleen and place gauze underneath, spreading out to isolate organ from surrounding anatomic features. 22 4. Clamp a hemostat to a #10 scalpel blade so that 3 mm ofthe tip is exposed. 5. Place a scale lengthwise along the lateral end ofthe spleen and make an incision 20 mm long. 6. Once bleeding has begun, lightly dab incision with gauze and immediately apply fibrin sealant with test applicator. 7. Record time until essentially all bleeding has ceased (slight oozing). Continue to record time until complete has hemostasis occurs. Discontinue all time measurements after 10 minutes if still bleeding. 8. Move scale at least 20 mm proximally from the first incision and repeat steps 5 through 7. 9. Continue to make incisions and measurements by moving continually proximal from the previous incision as long as there is sufficient length remaining to do so. 10. Once all incisions have been made, the subject may then be sacrificed by standard means. The performance of each tested applicator was assessed using the following criteria: 1. Time to near complete hemostasis (slight oozing). 2. Time to complete hemostasis. 3. Percentage of sites with hemostasis as a function of time within 10 minutes. 4. Quantity of sealant delivered. The results set forth in Table 1 below were obtained: TABLE 1 : COMPARATIVE TEST RESULTS Hemostasis in Rabbits Kidney 1 Kidney 2 Spleen Rabbit 1 20 seconds 25 seconds 1 minute Haemedics (2 applications) 48 seconds Applicator *had to clean out passages (2 applications) total 2 nd for all 3 incisions used Rabbit 2 48 seconds 12 seconds 50 seconds Haemedics (3 applications) (1 applications) (3 applications) Applicator Rabbit 3 < 1 second <1 second <1 second Inventive 1 ml 0.6 ml .1 ml Applicator *no bleeding through sealant very white in color 23 Rabbit 4 20 seconds 25 seconds <1 Inventive (poor applications) 0.6 ml Small leak on top due to Applicator 0.6 ml poor coverage. Sealant application sealed instantly Rabbit 5 25 seconds 1 minute 13 seconds >3 minutes Micromedics Haemedics 2 ml Applicator Rabbit 6 1 minute 25 seconds 1 minute 30 seconds 60 seconds Haemedics Inventive Applicator Inventive Applicator Applicator Referring to Figures 21-26, a spray head 300 according to another apect ofthe invention comprises a skull portion 302 carrying externally (Figures 21-23) two side-by-side forwardly directed spray nozzles 304 to supply individual patterns of fluid sealant components, ( a third, or even a fourth, nozzle could be added, if desired for therapeutic, indicator, conditioner, or other agents), a forwardly projecting, extensible nose 306 to apply suction, a rearwardly disposed connecting plate 308 and latches 310. Nozzles 304 can discharge relatively wide, overlapping patterns of sealant components, which mix on contact with a work surface (or in the air), enabling a multi-component sealant to be applied in a relatively wide swathe, for example to control extended area oozing tissues in surgery. Connecting plate 308 carries guide tabs 312 which are received into an applicator body and is generally similar to connnecting plate 112, Figures 7-19, but is simplified by the absence of a shuttle valve, since spray head 300, because it does not internally mix the sealant fluids, does not require clearing. Nose 306 has a laterally extended width and terminates in an extensible end portion 314 having multiple suction apertures 316 enabling suction to be applied across a wide swathe, mimicking the sealant swathe. Thus, by drawing the applicator, equipped with spray head 300, toward themselves, the user can prepare a wide are of tissue with suction in advance of application of sealant. Refeiring to the exploded view of Figure 24, in which component assembly is indicated by broken lines, spray head 300 is molded in complementary interlocking righthand and lefthand halves 300RH and 300LHand internally, has a telescopic suction tube 318 having a stop 320 which bears nose end portion 314, in extensible manner, and connects to a port 322 on connecting plate 308 to receive suction. Poppet valves 324 mount in rectangular cutouts 326 in spray head 300, carry spray nozzles 304, and connect with two sealant component sleeves 328 on connecting plate 308 via two elbow conduits 330. Sleeves 328 receive sealant fluids from syringes such as 62 (Figure 2) supported in the applicator body 332. (Figures 25-26). Poppet valves 324 comprise spring-biased valve elements, described in more detail 24 hereinbelow, which control sealant fluid flow out of nozzles 304 to provide a clean discharge of spray and avoid leakage, runs or dribbles. Referring to Figures 25-28, spray head 300 is shown assembled with an applicator body 332, details of which are described in the applications, which applicator body 332 can also be used with the droplet applicator head of Figures 7-19. Applicator body 332 comprises a suction port 334 connectable with a suction line, a depressible suction control valve 336, a depressible sealant fluid actuator trigger 338 and a manually retractable indicator bar 340 which can be used to draw fluid into syringes within the applicator to refill them from a filling tray such as that shown in the applications. As shown in Figure 25 the assembled spray applicator is designed to be held at an angle of the order of 30 degrees to the horizontal by a user with a fore finger above, and an index finger beneath skull portion 302, leaving the thumb free to operate actuator trigger 338 and suction control valve 336. Extensible nose 306 can be used as a probe or feeler gauge and can be drawn along a work surface 342, for example mammalian tissue to be treated, spacing spray nozzles 304 a suitable distance from the work surface 342. The user operates suction control valve 336 as nose 306 travels across work surface 342, as desired, to aspirate fluids and other debris through suction apertures 316 in end portion 314 across a relatively wide swathe. When sealant spray is desired, actuator trigger 338 is depressed, repeatedly if necessary, until sufficient pressure is built up in the fluid delivery system to open poppet valve 324 and release a conical pattern 344 of sprayed fluid from each poppet valve 324. The angle ofthe applicator to the work surface 342 means that an elliptical pattern 346 of spray is deposited on the work surface, as shown in idealized manner in Figure 26. Spray nozzles 304 are oriented so that their spray patterns overlap as completely as practicable at the intended work surface distance, and as indicated in Figure 26, this overlap can be, at least theoretically, very nearly complete. The sealant components are thus separated from one another until after they leave the spray head, thereby avoiding any possible problems of clogging within the spray head. By suitable selection of spray nozzle 304, and valve 324, fine sprays can be obtained ensuring that with the excellent overlap illustrated in Figure 26, thorough mixing ofthe sealant components takes at the work surface, providing excellent efficacy of sealant application enabling, for example, rapid hemostasis, control of oozing or such desired surgical result. As shown in Figures 27 and 28 the spray pattern can be enlarged and controlled by extending end portion 314, giving nose 306 a greater length and, as it were, lengthening the feeler gauge to distance the spray nozzles 304 from the work surface. If desired, detents can be provided to enable end portion 314 to be locked in any one of a variety of positions, or friction control may be used to make its extension 25 continuously selectable. Reducing pressure on trigger 338 causes poppet valve 324 to close, terminating the spray cleanly, without dribbles. With this system, employing fluid reservoirs in the applicator, such as syringes of 62 enables sprayed sealant to be delivered continuously for a substantial period of time, as determined by the capacity of a syringe. Use ofthe poppet valve system is particularly helpful when one or more ofthe sprayed components is significantly viscous. Thus the poppet valve can be selected to have a suitable release pressure such as to ensure that the viscous fluid is properly discharged, without premature dribbling. To this end, it will be understood that the poppet valves and nozzles used in a given spray head may differ according to the liquid to be sprayed, for example, using a less viscous liquid on one side and a more viscous liquid on the other. Three or more liquids can be sprayed, from three or more spray nozzles 304, if desired, for example two sealant components and a therapeutic agent. The alternative construction of spray head shown in Figure 29 employs a separator 342 between the spray nozzles 304 (one shown), to avoid cross-contamination, and uses a spring-biased ball-type poppet valve 346 to control discharge of fluid from the spray head, as shown in Figure 30. With suitable modification, the poppet valve shown can serve as valve 324 for the spray head of Figures 25-28. Referring to Figure 30, a sealant fluid is delivered through a conduit 348 to port 350 which is closed by ball 352 held in sealing engagement therewith by compression spring 354. When the user builds sufficient pressure in passage 348 to overcome the action of spring 354, by depressing actuator trigger 338, ball 352 moves away from port 352 allowing fluid to pass through passage 356 to spray nozzle 304 where it is discharged from orifice 358. The embodiment of applicator shown in Figure 31 is designed for the commercial supply of dual charges of sealant components, e.g. a fibrinogen containing component and a thrombin containing component as an integral disposable cartridge which can readily be removed from and replaced in the applicator and is not intended to be refilled, as are syringes 62. For this purpose, the rearward end of an applicator body 360 such as applicator body 332 is openable to receive a replaceable cartridge 362 which in addition to two sterilized and sealed syringe containers 364 comprises such ofthe functional elements ofthe applicator drive mechanism as are necessary to provide for replaceability in the stressful, time-sensitive environment of an operating room, for example, as shown, plungers 366, a rack 368, a coupling 370 between the two and a pull tab 372, which components are fixedly mounted in a tray 374. Containers 364 have removable tips 376 that are removed prior to insertion ofthe cartridge or breached by internal structure in the applicator (not shown). Optionally, containers 364 could be separable from cartridge 362, 26 to be also replaceable, but if so, they should preferably be paired and keyed to ensure that the user can quickly insert the right combination of components in the applicator. While illustrative embodiments ofthe invention have been described above, it is, of course, understood that various modifications will be apparent to those of ordinary skill in the art. Such modifications are within the spirit and scope ofthe invention, which is limited and defined only by the appended claims. 27

Claims: Claims 1. A manually actuated sealant applicator for dispensing a mixed output of at least two fluid sealant components capable, when mixed together, of generating a solid sealant product, the applicator comprising a mixing head having: a) a mixing volume (66, 148) for mixing the at least two fluid sealant components; b) at least two fluid sealant component delivery passages (59) each passage (59) connecting with the mixing volume (66, 148) to deliver an individual one of the sealant components separately to the mixing volume (66, 148) with a sealant component input direction; c) a dispensing tube (70) connecting with the mixing volume (66, 148) to receive a stream of mixed fluid sealant from the mixing volume in a mixed sealant output direction and to dispense the mixed stream at a location displaced away from the mixing volume; characterized in that the flow of each sealant component through the mixing chamber from the respective delivery passage (59) to the dispensing tube (70) undergoes a sharp change of direction in the mixing volume, to encourage mixing. 2. An applicator according to claim 1, characterized in that the sharp change of direction comprises an angle of at least 60° between the sealant component input direction and the mixed sealant output direction. 3. An applicator according to claim 1 or 2, characterized in that the shaφ change of direction is effected by impingement ofthe flow of one sealant component on the flow of at least one other sealant component. 4. An applicator according to claim 1, characterized in that the mixing volume has a cross-sectional area in the vicinity ofthe delivery passages (59) being greater than the sum ofthe cross-sectional areas of the delivery passages (59), said cross-sectional areas being determined transversely to the direction of fluid flow, to facilitate mixing ofthe fluid components. 5. An applicator according to claim 1, 2, 3 or 4 characterized in that the applicator comprises a clearing mechanism (170) to act on residual solid material in the mixing volume (66, 148) to clear the solid material from the mixing volume (66, 148). 6. An applicator according to claim 5, characterized by comprising a sealant component valve (54) actuated by the clearing mechanism (170) to close the sealant delivery passages (59) and prevent flow of the sealant components into the mixing volume (66, 148) during clearing. 7. An applicator according to claim 6, characterized in that the mixing volume (66, 148) further comprises a clearing port (69) for removal of undesired solids by the clearing mechanism (170) and in 28 that the sealant component valve (54) is operative to close the clearing port (69) when sealant is dispensed and to open clearing port (69) when the clearing mechanism (170) is operative. 8. A sealant applicator for dispensing a mixed output of multiple fluid sealant components, the components forming a solid sealant when mixed, the applicator comprising a mixing head having a mixing volume (66, 148), respective multiple sources for the multiple fluid sealant components and a dispensing tube to dispense the mixed output from the mixing volume characterized in that the applicator provides turbulent mixing ofthe combined fluid components. 9. A sealant applicator according to claim 8, characterized by comprising a mixing chamber within the mixing head, wherein the turbulent mixing of combined fluid sealant components takes place in the mixing chamber. 10. A sealant applicator according to claim 9, characterized in that turbulent mixing is created in the mixing chamber by constructing the chamber and fluid supply channels communicating therewith so that there is impingement mixing ofthe fluid flows in the mixing chamber. 1 1. A sealant applicator according to claim 8, characterized by comprising a clearing mechanism to remove deposits from the mixing volume. 12. A sealant applicator according to claim 3, characterized in that the clearing means comprises retrograde suction. 13. A sealant applicator for dispensing a mixed output of at least two fluid sealant components, the components forming a solid structure when mixed, the applicator comprising: a) a mixing chamber having a central mixing volume (66, 148); b) a passageway for transferring the fluid sealant components from a source to an open port in the mixing chamber; and c) a passageway for dispensing the mixed output from the mixing chamber; characterized in that turbulent mixing ofthe fluid sealant components takes place in the mixing chamber. 14. A sealant applicator according to claim 13, characterized in that each passageway for transferring the fluid sealant components to the mixing chamber is a resiliently flexible tube, having walls that can be pinched closed to prevent flow of fluid therethrough. 15. A sealant applicator according to claim 13, characterized in that the mixing chamber has ports 29 (68) for admission ofthe fluid sealant components, the ports (68) being diametrically opposed to one another across the central mixing volume (66, 148), and the mixing chamber has a cross-sectional area in the vicinity ofthe ports (68) greater than the combined cross-sectional areas ofthe ports (68) whereby the flows of fluid components into the mixing chamber impinge upon each other. 16. A sealant applicator according to claim 13, characterized in that the passageway for dispensing the mixed output from the mixing chamber comprises a tapered tube and nozzle. 17. A sealant applicator according to claim 13, characterized in that the mixing volume (66, 148) has a cross-sectional area greater than the sum ofthe cross-sectional areas within the passageways for transferring the fluid sealant components to an open port in the mixing chamber, to provide an air volume effective to facilitate mixing ofthe fluid components. 18. A sealant applicator according to claim 14, characterized by having a one-piece manifold, the manifold being formed of a resilient material and comprising the mixing chamber and the resiliently flexible tubes are of construction. 19. A sealant applicator according to claim 14, characterized in that each resiliently flexible tube has a cup-shaped fitting at one end, each ofthe fittings being secured to a source ofthe fluid sealant components. 20. A sealant applicator according to claim 19, characterized in that the cup-shaped fittings further comprise internal seals providing a fluid-tight attachment to each source ofthe fluid sealant components. 21. A multi-component handheld sealant applicator having respective fluid passageways connecting with sources ofthe sealant components and having at least one dispensing port characterized by comprising a one-piece flexible manifold formed of resilient material, the manifold connecting with the sources of sealant components and the at least one dispensing port. 22. A hand-held spray applicator for a multi-component sealant having multiple spray nozzles for discharging respective sprays ofthe individual components characterized by each nozzle comprising a spring-loaded poppet valve to control discharge of spray from the nozzle. 30 AMENDED CLAIMS [received by the International Bureau on 14 July 1999 (14.07.99); original claims 8-10, 13 and 15 amended; new claims 23 and 24 added; remaining claims unchanged (3 pages)] 8. A sealant applicator for dispensing a mixed output of multiple fluid sealant components, the components forming a solid sealant when mixed, the applicator comprising a mixing head having a mixing volume (66, 148), respective multiple sources for the multiple fluid sealant components and a dispensing tube to dispense the mixed output from the mixing volume wherein the applicator provides turbulent mixing ofthe combined fluid components in the mixing volume characterized in that the mixing volume is provided with a closable opening to permit clearing of the mixing volume. 9. A sealant applicator according to claim 8, characterized by comprising a clearing mechanism having a valve movable to open the closable opening to permit clearing of the mixing volume. 10. A sealant applicator according to claim 9, characterized by comprising a mixing chamber within the mixing head, wherein turbulent mixing is created in the mixing chamber by constructing the chamber and fluid supply channels communicating therewith to provide opposed flow of the sealant components into the mixing chamber and impingement mixing ofthe sealant component fluid flows in the mixing chamber. 1 1. A sealant applicator according to claim 8, characterized by comprising a clearing mechanism to remove deposits from the mixing volume. 12. A sealant applicator according to claim 3, characterized in that the clearing means comprises retrograde suction. 13. A sealant applicator for dispensing a mixed output of at least two fluid sealant components, the components forming a solid structure when mixed, the applicator comprising: a) a mixing chamber having a mixing volume (66, 148); b) a separate passageway for transferring each fluid sealant component from a respective source to an open port in the mixing chamber; and c) a passageway for dispensing the mixed output from the mixing chamber; characterized in that the separate fluid sealant component passageways are opposed at the mixing chamber to provide turbulent impingement mixing ofthe fluid sealant component flows in the mixing chamber. 31 14. A sealant applicator according to claim 13, characterized in that each passageway for transferring the fluid sealant components to the mixing chamber is a resiliently flexible tube, having walls that can be pinched closed to prevent flow of fluid therethrough. 15. A sealant applicator according to claim 13, characterized in that the mixing chamber has ports (68) for admission of the fluid sealant components, the ports (68) being diametrically opposed to one another across the central mixing volume (66, 148), and the mixing chamber has a cross-sectional area in the vicinity ofthe ports (68) greater than the combined cross-sectional areas of the ports (68). 16. A sealant applicator according to claim 13, characterized in that the passageway for dispensing the mixed output from the mixing chamber comprises a tapered tube and nozzle. 17. A sealant applicator according to claim 13, characterized in that the mixing volume (66, 148) has a cross-sectional area greater than the sum ofthe cross-sectional areas within the passageways for transferring the fluid sealant components to an open port in the mixing chamber, to provide an air volume effective to facilitate mixing ofthe fluid components. 18. A sealant applicator according to claim 14, characterized by having a one-piece manifold, the manifold being formed of a resilient material and comprising the mixing chamber and the resiliently flexible tubes are of construction. 19. A sealant applicator according to claim 14, characterized in that each resiliently flexible tube has a cup-shaped fitting at one end, each of the fittings being secured to a source of the fluid sealant components. 20. A sealant applicator according to claim 19, characterized in that the cup-shaped fittings further comprise internal seals providing a fluid-tight attachment to each source of the fluid sealant components. 21. A multi-component handheld sealant applicator having respective fluid passageways connecting with sources ofthe sealant components and having at least one dispensing port characterized by comprising a one-piece flexible manifold formed of resilient material, the manifold connecting with the sources of sealant components and the at least one dispensing port. 22. A hand-held spray applicator for a multi-component sealant having multiple spray nozzles for discharging respective sprays of the individual components characterized by each nozzle comprising a spring-loaded poppet valve to control discharge of spray from the nozzle. 32 23. A manually actuated sealant applicator for dispensing a mixed output of at least two fluid sealant components capable, when mixed together, of generating a solid sealant product, the applicator comprising a mixing head having a) a mixing volume (66, 148) for mixing the at least two fluid sealant components; b) at least two fluid sealant component delivery passages (59) each passage (59) connecting with the mixing volume (66, 148) to deliver an individual one of the sealant components separately to the mixing volume (66, 148); and c) a dispensing tube (70) connecting with the mixing volume (66, 148) to receive mixed fluid sealant from the mixing volume and to dispense the mixed stream at a location displaced away from the mixing volume; characterized in that the mixing volume (66, 148) and the at least two fluid sealant component delivery passages (59) are comprised by a one-piece manifold member formed of resiliently flexible material. 24. An applicator according to claim 23 characterized by comprising a pinch valve to pinch closed the two flexible-walled sealant component delivery passages (59). 33 STATEMENT UNDER ARTICLE 19(D Applicant's invention, as defined in claim 1 relates to a multi-component sealant applicator which is particularly, but not exclusively, suited to application of fibrin sealants in a surgical environment and which provides for the sealant components to be mixed in a mixing chamber. Claim 1 calls for the flow of each sealant component through the mixing chamber to undergo a sharp change of direction to encourage mixing. The International Search Report cited a single reference, Speer U.S. patent no. 4,040,420 as being of particular relevance to claims 1-22. Applicant respectfully disagrees. Speer teaches a multi-component sealant applicator which can be fitted with various needle block assemblies 100 (Figs. 2 & 4), 116 (Fig. 5) or 130 (Fig. 6). Assembly 100 (Figs. 2 & 4) lacks a mixing chamber and is not all relevant. Assembly 116 (Fig. 5) has a Y-shaped dispensing structure comprised by conduits 118, 120 and 124, which structure is similar to the prior art embodiment of Figure 1 of the present application. This structure does not provide a sharp change in direction of the sealant flows through the mixing chamber, as claimed by applicant and, as reported in the specification at page 3 lines 12-24, results in incomplete mixing. Needle block assembly 130 (Fig. 6) comprises a ball-like mixing chamber 132 of expanded cross-sectional area which produces turbulence to force the fluids or liquids to mix, see column 6 lines 24-40. However, if even a new block assembly 130 does not provide applicants claimed sharp change of direction of fluid flow in the mixing chamber. The flow directions provided by conduits 118 and 120 into mixing chamber 132 and by conduit 126 leaving mixing chamber 132 are similar to the Y-shaped configuration of the Fig. 5 embodiment, which provides only a small change in direction. While small quantities of fluid may (or may not) change direction more sharply within mixing chamber 132 during the filling of mixing chamber 132, the possibility that subsequent fluid flow through the chamber 132 34 will be significantly laminar, resulting in poor mixing, remains. Claim 2 which calls for the sharp change of direction to comprise an angle of at least 60° is clearly and undoubtedly distinguished from Speer whose corresponding angle in Fig. 5 appears to be no more than 15°" and in Fig. 6 no more than 10°. Nor does Speer disclose effecting the sharp change of direction by impingement flow, as claimed in claim 3. The impingement of Speer 1 s fluids in the Y-shaped dispensing member of Fig. 5 or mixing volume 132 of Fig. 6 produces only a small change in direction. Nor does Speer teach a clearing mechanism as claimed in claims 5-7. Speer's block assemblies have to be replaced after a moment of non-use, see column 6, lines 62-68. In contrast, applicant's applicator equipped with a clearing mechanism is reusable. New independent Claim 8 acknowledges that Speer purports to teach turbulent mixing in a mixing chamber, but it is not admitted that Speer's structure is necessarily effective. New Claim 8 is distinguished by provision of a closable opening for clearing the mixing volume, which is not remotely suggested by Speer. New claim 9 claims a teaches a clearing mechanism having a valve movable to open the opening. Claims 10-12 further distinguish from Speer. New independent Claim 13 is distinguished from Speer in its recitation of opposed flow impingement mixing, and dependent claims 14-22 provide additional distinguishing features. New independent claim 23 recites a flexible manifold which is not remotely suggested by Speer. 35

Inventors: EPSTEIN GORDON HOWARD, PLYLEY ALAN KIRBY, REDMOND RUSSELL JAMES, EPSTEIN, GORDON, HOWARD, PLYLEY, ALAN, KIRBY, REDMOND, RUSSELL, JAMES
Applicants: BIOSURGICAL CORP, EPSTEIN GORDON HOWARD, PLYLEY ALAN KIRBY, REDMOND RUSSELL JAMES, BIOSURGICAL CORPORATION, EPSTEIN, GORDON, HOWARD, PLYLEY, ALAN, KIRBY, REDMOND, RUSSELL, JAMES
Application year: 1999
Main classification: A61M37
IPC codes: A61B17, B05B7, B05C17