Abstract:
Provided is a device for the dispensing of powders of the type in which a generated gas flow entrains the powder to be dispensed and carries the powder from the device via a barrel. The barrel has a bore including a main portion with a continuous internal surface, and is characterized in that the length of the main portion is at least fifteen times its maximum internal diameter; and/or the internal bore of the main portion is tapered; and/or the barrel has an outwardly flared outlet portion.

Description:
TECHNICAL FIELD 
       [0001]    This invention relates to improvements in a device for the dispensing of powder. In particular, the invention relates to an improvement in devices of the general type disclosed in International Patent Application WO2010/070333 (which is hereby incorporated by reference). Such devices are of particular utility in surgical procedures or other medical applications, for the topical delivery of powder to an internal or external surface of the body. 
       BACKGROUND 
       [0002]    In devices of the type disclosed in WO2010/070333, a flow of gas entrains powder that is to be dispensed and carries that powder out of the device via a barrel. The barrel serves to direct the powder to the desired application site. In the devices illustrated in WO2010/070333, the barrels are rather short and are of simple construction. 
       BRIEF SUMMARY 
       [0003]    It has now surprisingly been found that the performance of devices of the type disclosed in WO2010/070333 may be substantially improved by modifications to the design of the barrel. In particular, elongation of the barrel and/or the incorporation of certain structural features in the internal bore of the barrel lead to improvements. 
         [0004]    Thus, according to the invention there is provided a device for the dispensing of powder, the device being of the type in which a generated gas flow entrains the powder to be dispensed and carries the powder from the device via a barrel, the barrel having a bore including a main portion with a continuous internal surface, characterized in that: 
         [0005]    (a) the length of the main portion is at least fifteen times its maximum internal diameter; and/or 
         [0006]    (b) the internal bore of the main portion is tapered; and/or 
         [0007]    (c) the barrel has an outwardly flared outlet portion. 
         [0008]    The device according to the invention is advantageous in that the form of the barrel may lead to certain improvements in performance. In particular, the form of the barrel may be chosen in such a way that the shape of the plume of powder emitted from the device is optimised for a particular application. Thus, the distribution of powder on the intended site of application may be made more uniform. In addition, the velocity of the powder plume may be increased, and this may result in the form of the plume being maintained over greater distances, so that the powder plume remains intact when projected over larger distances than those obtained with a conventional device, enabling the powder delivery device to be held a greater distance from the desired delivery site. This may be advantageous, for instance, in surgical procedures where it may not be possible to hold the device close to the intended site of application of the powder. In addition, fall-off of powder from the plume, under the influence of gravity, may be reduced, leading to reduced deposition of powder at undesired locations. In addition, the outlet may be less prone to clogging, improving performance and reducing the maintenance required. Dispersion of the powder as it leaves the device may also be improved. In general, the device according to the invention may operate effectively over a wide range of gasflow pressures, e.g., from about 0.5 bar to about 7 bar, though for most applications pressures in the range 0.5 bar to 2 bar are generally satisfactory, e.g., from 0.5 bar to 1.5 bar. 
         [0009]    In some preferred embodiments of the device, the length of the main portion is at least fifteen times its maximum internal diameter; and the internal bore of the main portion is tapered. 
         [0010]    In other embodiments of the device, the barrel has an outwardly flared outlet portion. 
         [0011]    In some particularly preferred embodiments of the device: 
         [0012]    (a) the length of the main portion is at least fifteen times its maximum internal diameter; and 
         [0013]    (b) the internal bore of the main portion is tapered; and 
         [0014]    (c) the barrel has an outwardly flared outlet portion. 
         [0015]    In embodiments in which the barrel is elongated, the barrel may be rigid or it may be flexible. 
         [0016]    In rigid embodiments, the length of the main portion of the barrel is at least fifteen times, e.g., at least eighteen times or at least twenty times, its maximum internal diameter, or more. 
         [0017]    In rigid embodiments, the length of the main portion is typically between about 30 mm and 100 mm, e.g., about 50 mm or about 75 mm. The maximum internal diameter of the main portion is typically from 1 mm to 6 mm, e.g., about 2 mm or about 3 mm. 
         [0018]    In flexible embodiments of the barrel, the barrel is generally longer than for rigid embodiments, the length of the main portion of the barrel typically being between about 50 mm and about 300 mm, more commonly between about 50 mm and about 200 mm, and typically between about 100 mm and 180 mm, e.g., about 150 mm. The internal diameter of the barrel in such embodiments is most commonly between about 1 mm and about 6 mm, typically between about 1.5 mm and about 4 mm, e.g., about 2 mm or about 3 mm. 
         [0019]    In order for the barrel to be flexible, its main portion is typically formed as a plastics tube, the plastics material being such that the tube may be manually deformed to the required shape without occlusion of the internal bore. The nature of the required shape will generally be dictated by the circumstances of the procedure in which the device is being used. Most commonly, a single bend may be introduced into the barrel by the user of the device, but in other situations it may be necessary to form the barrel into a more complex shape, e.g., with a double bend (i.e. an “S”-shape or the like). It has surprisingly been found that, even when bent into shapes as extreme as are ever likely to be required in practice (e.g., two 90° bends), the pattern of powder dispensed from the device can remain satisfactory in terms of the geometry of the plume of powder emerging from the distal end of the barrel and the pattern of deposition of the powder. 
         [0020]    The nature of the plastics material from which the flexible elongate barrel is formed may be such that the tube retains the shape into which it is deformed, at least for as long as is required during normal use. Preferably, however, the barrel incorporates one or more malleable elongate members that can be readily deformed, and which have the effect of retaining the barrel in the desired configuration until it is once again manually deformed to another configuration. Such members may take the form of wires or rods of metal or other malleable material that are incorporated into the barrel. Most commonly, such wires or rods are disposed parallel to the longitudinal axis of the barrel. In some embodiments, the main portion of the barrel is a tube having more than one lumen, one lumen (normally the one having the greatest cross-sectional area) constituting the bore of the barrel along which powder is dispensed, and at least one lumen accommodating one or more wires or rods. In other embodiments, one or more wires or rods are embedded in the plastics material from which the barrel is formed. There may be just one such wire or rod, or there may be two, three, four or more such wires. Where there is more than one wire or rod, those wires or rods are most commonly equiangularly spaced around the main portion of the barrel. 
         [0021]    Forms of material that are suitable for the malleable wires or rods are copper wire and copper-coated steel wire. In one currently preferred embodiment, a single such wire is embedded in the wall of the tube that constitutes the main portion of the barrel. In other embodiments, two, three or four such wires may be used. 
         [0022]    In other embodiments, another form of malleable material may be used to enable the form of the barrel to be altered. For instance, the main portion of the barrel may be provided, along the whole or part of its length, with a sheath of material that holds its shape when deformed, e.g., a foam material of the type known as memory foam or visco-elastic foam. 
         [0023]    In embodiments in which the internal bore of the main portion is tapered, the internal diameter of the bore may decrease from the upstream to the downstream end of the main portion, i.e., the internal bore of the main portion may converge. Alternatively, the internal diameter of the bore may increase from the upstream to the downstream end of the main portion, i.e., the internal bore of the main portion may diverge. The taper angle may typically be in the range 0.5° to 3°, more commonly 0.5° to 2°. 
         [0024]    Embodiments in which the main portion of the barrel is flexible typically have a main portion that is considerably longer than is the case for rigid embodiments. Those flexible embodiments are typically formed by extrusion and in such cases will therefore have an internal bore of constant cross-section. Embodiments in which the main portion of the barrel is rigid are more commonly formed by injection moulding, in which case the internal bore of the main portion of the barrel may have a uniform cross-section or may, more preferably, be tapered. 
         [0025]    In embodiments in which the barrel has an outwardly flared outlet portion, the outlet portion typically has a length of between 5 mm and 25 mm, more commonly between 5 mm and 10 mm. The internal diameter of the outlet portion may increase from its upstream to its downstream end by a factor of two or more. As will be readily appreciated, where the outlet portion is “flared”, that term refers to the internal shape of the outlet, i.e., to a widening of the outlet from its upstream to its downstream end. That widening may or may not be reflected in the external shape of the outlet. 
         [0026]    Apart from the modifications to the barrel described above, the device according to the invention may be as described in WO2010/070333, in particular in relation to  FIGS. 3 to 12  of that document. Briefly summarised, such a device has a main body that may comprise upper and lower housing components formed in plastics material by injection moulding. The main body may have the general form of an elongate cylinder that is adapted to be held in a user&#39;s hand, the underside of the lower component being shaped to facilitate such grip. A push button-type actuator may be mounted in the top of the main body such that, when the device is held by the user, the actuator can be depressed by the thumb of the hand that holds the device. A flexible tube may extend from the rear end of the device and may be adapted to be connected to a gas source, e.g., a source of compressed air. A connector may be provided at the distal end of the tube. A vial containing the powder that is to be dispensed from the device may be coupled to the device, e.g., via an upstanding spigot that is received within the mouth of the vial. The barrel may extend from the front end of the device. 
         [0027]    The barrel may be provided with a mounting that enables its orientation relative to the main body of the device of which it forms part to be varied. For instance, the barrel may engage the main body of the device in the manner of a ball-and-socket connector, so that the orientation of the barrel may be adjusted, e.g., manually by the operator. 
         [0028]    In presently preferred embodiments, however, the barrel is connected to the main body of the device in a fixed orientation. The barrel may be connected to the main body by a threaded connection, or by a suitable quick release connection such as a bayonet fitting. Other forms of connection may alternatively be used, e.g., a luer lock-type connection, or an interference fit or the like. 
         [0029]    The device according to the invention may be manufactured using medical grade materials, most components being most conveniently manufactured in plastics by techniques such as injection moulding and extrusion. Where appropriate, components may be manufactured in other materials, e.g., glass or metal. 
         [0030]    The device according to the invention may be used to deliver a wide variety of powders to a surface of the body. Such powders include agents intended to have a therapeutic effect, either in terms of a pharmacological effect on the body or as disinfectants or the like useful in the prevention or treatment of infections. One particular field in which the device of the invention is useful, however, is for the delivery of haemostatic powder compositions to internal tissues exposed during surgical procedures or after traumatic injury. Such haemostatic compositions, which may also be described as tissue sealants, may for instance comprise dry powder mixtures of fibrinogen and thrombin. Such a mixture is essentially inert when formulated in the dry state, but once hydrated, e.g., upon application to a bleeding wound, the mixture leads to the production of fibrin which cross-links to form a blood clot. 
         [0031]    Thus, according to a further aspect of the invention, there is provided a method of delivering a haemostatic composition to an internal tissue exposed during surgical procedures or after traumatic injury, which method comprises providing a device as described above, which device is charged with a quantity of a haemostatic composition in dry powder form, and dispensing said composition from said device onto said tissue. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0032]    The invention will now be described in greater detail, by way of illustration only, with reference to the accompanying drawings, in which: 
           [0033]      FIG. 1  is a perspective view of a first embodiment of a powder delivery device according to the invention; 
           [0034]      FIG. 2  is a side view of the device of  FIG. 1 ; 
           [0035]      FIG. 3  shows a barrel that forms part of the device of  FIG. 1 ; 
           [0036]      FIG. 4  is a cross-sectional view of the barrel of  FIG. 3 ; 
           [0037]      FIGS. 5(   a ) and ( b ) illustrate the range of vertical movement of the barrel; 
           [0038]      FIGS. 6(   a ) and  6 ( b ) illustrate the range of lateral movement of the barrel; 
           [0039]      FIG. 7  is a perspective view of a second embodiment of a powder delivery device according to the invention, showing the barrel separated from the main body of the device; 
           [0040]      FIG. 8  is a perspective view from behind of the barrel of the device of  FIG. 7 ; 
           [0041]      FIG. 9  is a cross-sectional view of the barrel of  FIG. 8 ; 
           [0042]      FIG. 10  is a perspective view of a third embodiment of a powder delivery device according to the invention, comprising the main body of the second embodiment with an alternative form of barrel attached to it; 
           [0043]      FIG. 11  is a perspective view of the barrel shown in  FIG. 10 ; and 
           [0044]      FIG. 12  is a cross-sectional view of the barrel of  FIG. 11 . 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0045]    Referring first to  FIGS. 1 and 2 , a first embodiment of a powder delivery device in accordance with the invention is generally designated  20 . Save for the inventive modification described in greater detail below, the device  20  is of similar form to the device illustrated in  FIGS. 3 to 12  of WO2010/070333. Briefly summarised, the device  20  has a main body that comprises upper and lower housing components  23   a,    23   b  that are formed in plastics material by injection moulding. The main body has the general form of an elongate cylinder that is adapted to be held in a user&#39;s hand, the underside of the lower component  23   b  being shaped to facilitate such grip. A push button-type actuator  27  is mounted in the top of the main body such that, when the device  20  is held by the user, the actuator  27  can be depressed by the thumb of the hand that holds the device  20 . 
         [0046]    A flexible tube  25  extends from the rear end of the device  20  and is adapted to be connected to a gas source, e.g., a source of compressed air (not shown). A suitable connector  26  is provided at the distal end of the tube  25 . 
         [0047]    A glass vial  31  is coupled to the device  20  via an upstanding spigot (not visible) that is received within the mouth of the vial  31 . A pair of clips  35  engages with a peripheral lip of the vial  31 , so as to hold it securely in place. In other embodiments, the vial  31  may simply engage the spigot or similar formation with an interference fit and/or the spigot or similar formation may have a degree of resilience enabling a clip-type fitting to the vial. To facilitate sealing engagement of the vial  31  with the device  20 , the formation that receives the mouth of the vial  31  may incorporate or be formed from a suitable elastomeric material (e.g., a thermoplastic elastomer). A device  20  having such a fitting may be produced using a two-shot molding process. 
         [0048]    As for the device described in WO2010/070333, the front end of the device  20  is provided with a tubular barrel  29 , through which powder is dispensed from the device  20 . The barrel  29  in the present invention, however, is rather different in form to that described in the earlier patent application, as is discussed in greater detail below. 
         [0049]    The base of the spigot with which the vial  31  is engaged is closed by a perforated plate, such that when the device is in the operative orientation shown in  FIGS. 1 and 2 , powder contained within the vial  31  rests upon the perforated plate. When the actuator  27  is depressed, gas is caused to flow through the device  20 , as described in WO2010/070333. The flow of gas has two, related, effects. First, the gas flow drives a mechanical agitator in the form of a ball that is held captive within a circular track; rotation of the ball around the track induces vibrations in the device  20 , the effect of which is to dislodge powder from the vial  31 , through the perforated plate that constitutes the base of the spigot that is engaged by the vial  31 . Secondly, a proportion of the gas flow is directed at the underside of the perforated plate, entrains the powder that is dislodged from the vial  31  and carries it from the device  20  via the barrel  29 . 
         [0050]    Thus, to dispense powder from the device  20 , the user holds the device  20  in one hand, directs the barrel  29  at the intended site of application of the powder, and depresses the actuator  27  with the thumb. This permits gas to flow through the device  20 , causing the ball to rotate rapidly around the track and inducing a degree of mechanical vibration that is transmitted to the vial  31 . Most of the gasflow is vented from the device  20 . However, a small proportion of gas is directed at the underside of the perforated plate. The mechanical agitation of the device  20  caused by rotation of the ball within the track facilitates the release of powder from the vial  31 . The powder is entrained in the flow of air that escapes from the device  20  via the barrel  29 . The powder is blown out of the device  1  and deposited on the site of application. 
         [0051]    As noted above, the device  20  differs from that disclosed in WO2010/070333 in the form of the barrel  29 . The barrel  29  is shown in  FIGS. 3 and 4 . 
         [0052]    As can be seen in  FIG. 3 , the barrel  29  is elongate and of circular cross-section, extending from a ball-type connector  291  at one end to a flared outlet  292  at the other. The ball-type connector  291  is captivated within an opening at the front of the main body of the device  20 , between the upper and lower housing components  23   a,    23   b,  in the manner of a ball-and-socket joint. 
         [0053]    As can be seen from  FIG. 4 , the barrel  29  has an internal bore having an entry portion  293  that is of constant diameter, a main bore  294  that is of reduced diameter relative to the entry portion  292 , and an outlet portion  295  within the flared outlet  292 . The diameter of the main bore  294  reduces along its length. 
         [0054]    The overall length of the barrel  29  is approximately 70 mm. The entry portion  293  of the internal bore has a diameter of approximately 5 mm and a length of approximately 8 mm. The diameter of the main bore  294 , which has a length of approximately 48 mm, reduces from approximately 3.5 mm adjacent the entry portion  293  to approximately 2 mm where the main bore  294  meets the outlet portion  295 . The angle of convergence of the internal wall of the main bore  294  relative to its longitudinal axis is thus approximately 1°. 
         [0055]    The entry portion  293  receives a tube (not visible in the drawings) by which the gasflow and entrained powder are fed from the main body of the device  20  to the barrel  29 . 
         [0056]    The narrowing of the main bore  294  may cause an increase in velocity of the gasflow as it exits the device  20  and, together with the flared form of the outlet portion  295 , this may help to maintain the shape of the powder plume emitted from the device  20 , resulting in good coverage of the application site with powder. Fall off of powder from the emitted plume, under the influence of gravity, may be reduced, minimising the amount of powder that is dispensed onto sites other those to which the powder is intended to be delivered. The flared form of the outlet portion  295  also leads to a reduced likelihood of clogging. 
         [0057]    In this embodiment, directional control over the emitted powder is achieved by virtue of the fact that the ball-type connector  291  permits the orientation of the barrel  290  relative to the main body of the device  20  to be varied over a wide range, both vertically (see  FIGS. 5(   a ) and  5 ( b )) and laterally ( FIGS. 6(   a ) and  6 ( b )). 
         [0058]    Turning now to  FIG. 7 , a second embodiment of a powder delivery device according to the invention is generally designated  30 . The device  30  is broadly similar to the first embodiment  20  described above in that it comprises a main body  123  that receives vial  131  of powder. In this embodiment, the vial  131  is received within a ring  137  of thermoplastic elastomer that is molded onto the upper component of the main body  123  in a two-shot molding process. 
         [0059]    Like the first embodiment  20 , the device  30  comprises a tubular outlet barrel  39 . In the second embodiment  30 , however, the barrel  39  connects to the main body  123  by means of a bayonet fitting and has a fixed orientation relative to the main body  123 . 
         [0060]    As can be seen in  FIG. 8 , the face of the barrel that abuts the main body  123  is formed with a male bayonet spigot  391  with a central recess that receives the open end of a tube  135  (see  FIG. 7 ) by which the gasflow and entrained powder are fed from the main body  123  of the device to the barrel  39 . The barrel  39  is injection moulded in rigid plastics material (eg ABS) and (referring to  FIG. 9 ), like the barrel  29  of the first embodiment  20 , is formed with an internal bore  394  that diminishes along its length (in this case from an internal diameter of approximately 2.9 mm to an internal diameter of approximately 2 mm). The barrel  39  has a flared outlet  392 . 
         [0061]    As for the first embodiment  20 , the narrowing of the main bore  394  may cause an increase in velocity of the gasflow as it exits the device  30  and, together with the flared form of the outlet  392 , this may help to maintain the shape of the powder plume emitted from the device  30 , resulting in good coverage of the application site with powder. Fall off of powder from the emitted plume, under the influence of gravity, may be reduced, minimising the amount of powder that is dispensed onto sites other than to which the powder is intended to be delivered. The flared form of the outlet  392  also leads to a reduced likelihood of clogging. 
         [0062]    Finally,  FIG. 10  depicts a third embodiment of a powder delivery device according to the invention, which is generally designated  40 . This embodiment differs from the second embodiment  30  solely in the form of the outlet barrel  49 . Indeed, the outlet barrel  39  of the second embodiment  30  and the outlet barrel  49  of the third embodiment  40  are interchangeable. 
         [0063]    The form of the barrel  49  is shown in greater detail in  FIGS. 11 and 12 . The barrel  49  comprises three components: a bayonet hub  491 , a flexible plastics tube  492  and an outlet tip  493 . 
         [0064]    The bayonet hub  491  is injection moulded in rigid plastics material (e.g., polyamide) and corresponds in overall shape to the proximal end of the rigid barrel  39  of the second embodiment  30 . It has a central bore  495  that terminates in a socket within which one end of the flexible tube  492  is received. That end of the tube  492  may be fixed to the hub  491  by adhesive, by ultrasonic welding or by any other suitable means. The other end of the tube  492  is received within a similar socket formed in the outlet tip  493  (which is also formed by injection moulding of a suitable material, e.g., polyamide) and may be fixed by similar means. The distal (downstream) part of the outlet tip  493  has a flared internal bore. 
         [0065]    The flexible tube  492  is formed by extrusion in polyurethane, a copper-coated steel wire  494  being embedded in the wall of the flexible tube  492  during manufacture. A user of the device may therefore form the flexible tube  492  into a desired configuration, the effect of the wire  494  being to retain the tube  492  in that configuration during use. The third embodiment  40  may be particularly useful in surgical procedures in which it is desired to deposit the powder onto surfaces that are hidden and at which a straight barrel cannot be directed.