Patent Publication Number: US-8523806-B2

Title: Sprayer

Description:
TECHNOLOGICAL FIELD 
     The present invention generally relates to a device for delivering a liquid material. More specifically, the invention pertains to a sprayer having useful application in the medical field for spraying a liquid at a body region. 
     BACKGROUND DISCUSSION 
     Conventionally, there is known a method in which two or more liquids are mixed and ejected to an affected part or the like of a living body to form, for example, an anti-adhesive material, a biological tissue adhesive, etc. Thus, developmental efforts in the area of sprayers have been made. 
     Such a sprayer is configured to feed components which coagulate upon mixing, such as a thrombin-containing solution and a fibrinogen-containing solution, in a mutually separated manner to the vicinity of the affected part, and to spray them while mixing at the affected part. 
     One conventional sprayer includes two syringes respectively containing different types of liquids, and a nozzle for mixing the liquids from respective syringes, and spraying the mixture. The sprayer is configured in the following manner. The nozzle is connected to a gas supply source that supplies an aseptic gas so that the liquids are ejected together with the aseptic gas. The nozzle is specifically configured as a double tube structure including two inner tubes positioned in an outer tube. The liquid from one syringe passes through one inner tube while the liquid from the other syringe passes through the other inner tube. During operation, the gas passes between the outer tube and the inner tubes. The distal end openings of the respective inner tubes function as liquid ejection ports for respectively ejecting the liquids. The distal end opening of the outer tube includes the liquid ejection ports disposed in the inside thereof, and functions as a gas ejection port for ejecting gas. 
     With the nozzle thus configured, upon stopping the liquid ejection operation, the residual pressures in the respective inner tubes cause the liquids to project outward from the liquid ejection ports in the respective inner tubes. In this state, the liquids are mixed with each other so that the liquids coagulate. As a result, clogging occurs in each liquid ejection port. Further, the liquids ejected outward from the liquid ejection ports of respective inner tubes also respectively extend to the gas ejection port. Accordingly, the liquids are also mixed with each other to coagulate at the gas ejection port, resulting in clogging. When spraying is once again tried after the occurrence of clogging, the coagulated liquids inhibit the ejection of the liquids from respective liquid ejection ports, and ejection of the gas from the gas ejection port. Thus, it is difficult to perform respraying. 
     SUMMARY 
     A sprayer disclosed here is able to reduce the occurrence of clogging following ejection of liquid from a nozzle. When a liquid is ejected from a nozzle, a gas flows into a liquid flow path through a vent from a gas flow path, and the liquid is ejected together with the gas. Then, when the ejection of the liquid is stopped, the pressure (the residual pressure) in the gas flow path causes the gas to flow into the liquid flow path through the vent. As a result, it is possible to blow off the liquid in the liquid flow path, particularly, in the merge part to the outside. This can prevent the occurrence of clogging in the nozzle with reliability. Further, the gas ejects outwardly from the inside of the liquid flow path together with the liquid. For this reason, it is possible to omit the provision of a gas ejection port for ejecting a gas as with a conventional sprayer. This can simplify, for example, the configuration of the nozzle. 
     According to one aspect, a sprayer comprises supply means for separately supplying a first liquid and a second liquid comprising different liquid compositions, and a nozzle comprising a first liquid flow path in fluid communication with the supply means and along which the first liquid flows, and a second liquid flow path in fluid communication with the supply means and along which the second liquid flows. The nozzle also comprises a gas flow path for allowing a gas to pass therethrough, and a merge part at which the first flow path and the second flow path merge so that the first liquid flowing along the first liquid flow path mixes with the second liquid flowing along the second liquid flow path to form a mixed liquid. The sprayer also includes at least one vent through which flows the gas which has passed through the gas flow path, with the at least one vent being located at the merge part of the liquid flow path or at a portion on an upstream side of the merge part relative to a direction of flow of the gas. 
     According to another aspect, a method of applying a mixed liquid to a living body involves supplying a first liquid along a first liquid path to a merge part of a nozzle, and supplying a second liquid along a second liquid path different from the first liquid path to the merge part of the nozzle to mix the first liquid and the second liquid together in the merge part to produce a mixed liquid, with the first and second liquids comprising different liquid compositions. The method further comprises supplying gas to the merge part at a point upstream of an ejection port of the nozzle and/or the first liquid path at a point upstream of a distal end of the first liquid path, and ejecting the mixed liquid and the gas from the ejection port of the nozzle at the living body. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view showing a first embodiment of a sprayer disclosed here. 
         FIG. 2  is a longitudinal cross-sectional view of the distal end part of a nozzle of the sprayer shown in  FIG. 1 , in one operational state of the sprayer. 
         FIG. 3  is a longitudinal cross-sectional view of the distal end part of a nozzle of the sprayer shown in  FIG. 1 , in another operational state of the sprayer. 
         FIG. 4  is a longitudinal cross-sectional view of the distal end part of a nozzle of the sprayer shown in  FIG. 1 , in another operational state of the sprayer. 
         FIG. 5  is a longitudinal cross-sectional view of the distal end part of a nozzle of the sprayer shown in  FIG. 1 , in another operational state of the sprayer. 
         FIG. 6  is a longitudinal cross-sectional view of the distal end part of a nozzle of the sprayer shown in  FIG. 1 , in an additional operational state of the sprayer. 
         FIG. 7  is a longitudinal cross sectional view of the distal end part of the nozzle of a sprayer according to a second embodiment. 
         FIG. 8  is a longitudinal cross-sectional view of the distal end part of the nozzle of a sprayer according to a third embodiment. 
         FIG. 9  is a longitudinal cross-sectional view of the distal end part of the nozzle of a sprayer according to a fourth embodiment. 
         FIG. 10  is a longitudinal cross-sectional view of the distal end part of the nozzle of a sprayer according to a fifth embodiment. 
         FIG. 11  is a longitudinal cross-sectional view of the distal end part of the nozzle of a sprayer according to a sixth embodiment. 
         FIG. 12  is a longitudinal cross-sectional view of the distal end part of the nozzle of a sprayer according to a seventh embodiment. 
         FIG. 13  is a plan view of the distal end part of the nozzle of a sprayer according to a further embodiment. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1-6  illustrate aspects of a sprayer utilizing a nozzle according to a first embodiment disclosed here. In the description below, for purposes of convenience and facilitating the description, the right hand side in  FIGS. 1-6 , and similarly for  FIGS. 7-15 , is referred to as the “proximal end” or “upstream side”; and the left hand side is referred to as the “distal end” or “downstream side”. 
     The sprayer  1  shown in  FIG. 1  is configured and sized to be inserted into the inside of the abdominal cavity. In addition, the sprayer is adapted to spray, while mixing two kinds of liquids having different liquid compositions (a first liquid L 1  and a second liquid L 2 ), the mixture to an organ, the abdominal wall, or the like during, for example, a laparoscopic surgery. 
     The sprayer  1  is used with a first syringe  2  storing the first liquid L 1  and a second syringe  3  for storing the second liquid L 2 , respectively mounted therein. The first syringe  2  and the second syringe each constitute liquid supply means for storing the respective liquid and for supplying the respective liquid. The first syringe  2  and the second syringe  3  have virtually the same configuration. 
     The first syringe  2  is filled with the first liquid L 1  while the second syringe  3  is filled with the second liquid L 2 . The first liquid L 1  contained in the first syringe  2  and the second liquid L 2  contained in the second syringe  3  have different compositions (components) from one another. 
     Preferably, the first liquid L 1  and the second liquid L 2  are appropriately selected according to the use of the sprayer  1 , the intended purpose, the particular situation, etc. For example, when the liquids L 1 , L 2  are used for administering an anti-adhesive material, one of the first liquid L 1  and the second liquid L 2  can be a liquid containing carboxymethyl dextrin modified with a succinimidyl group, and the other can be a liquid mixture of sodium carbonate and sodium hydrogencarbonate. Such a combination of the first liquid L 1  and the second liquid L 2  gelate when the two liquids are mixed together. 
     Of course, it is to be understood that the types and combinations of the first liquid L 1  and the second liquid L 2  are not limited to the ones mentioned above by way of example. 
     The first syringe  2  and the second syringe  3  are respectively connected to a nozzle  4 . A respective plunger  26  and gasket  24  is associated with each syringe, and is adapted to be pushed (moved) inwardly and operated. As a result, the first liquid L 1  is supplied into a first flow path  44  of the nozzle  4 , and the second liquid L 2  is supplied into a second flow path  45  of the nozzle  4  as shown in  FIG. 2 . The pressing operation of each plunger  26  is manually carried out by an operator of the sprayer  1 . 
     Referring generally to  FIGS. 1 and 4 , the sprayer  1  is configured to eject the first liquid L 1  and the second liquid L 2  together with an aseptic gas G. The presence of the gas G atomizes the mixture, which enables the mixture to be uniformly sprayed onto the desired site. The gas G is supplied from a gas cylinder  300   b . The gas cylinder  300   b  is connected to the nozzle  4  via a tube  302   b.    
     The gas cylinder  300   b  includes an internal space filled with or containing high pressure gas G. Thus, the gas cylinder  300   b  can supply the gas G flowing at a high speed to the sprayer  1  (nozzle  4 ). The intermediate part of the gas cylinder  300   b  or the tube  302   b  can be provided with a closable valve for controlling the supply/stoppage of supply of the gas G with respect to the sprayer  1 . For spraying the mixture, the valve is rendered in an open state. Examples of the gas G include carbon dioxide. 
     As shown in  FIG. 1 , the sprayer  1  includes a sprayer main body  7 , and the nozzle  4  located at the distal end side of the sprayer main body  7 . 
     The sprayer main body  7  includes a syringe holding part  71  for holding a barrel  21  of the first syringe  2  and a barrel  21  of the second syringe  3 , and a flange joint part  72  holding and joining together a flange  29  of the plunger  26  of the first syringe  2  and a flange  29  of the plunger  26  of the second syringe  3 . 
     The syringe holding part  71  is configured to fix the first syringe  2  and the second syringe  3  in parallel relation. The syringe holding part  71  has a fit part  711  into which an opening part  22  of each barrel  21  is fitted, an insertion part  712  positioned closer to the proximal end side than the fit part  711  and into which the edge of a flange  23  of each barrel  21  is inserted, and a joint part  713  joining the fit part  711  and the insertion part  712 . 
     When the opening part  22  of each barrel  21  is fitted into the fit part  711 , the opening part  22  of the first syringe  2  is connected to the first flow path  44  of the nozzle  4 , and the opening part  22  of the second syringe  3  is connected to the second flow path  45 . This enables supply of the first liquid L 1  into the first flow path  44 , and supply of the second liquid L 2  into the second flow path  45  as generally shown in  FIG. 4 . 
     The outer circumferential part of the fit part  711  includes a connection part  715  connected with the end of the tube  302   b  through which the gas G from the gas cylinder  300   b  passes. In the illustrated embodiment, the connection part  715  projects outwardly. When the tube  302   b  is connected to the connection part  715 , the tube  302   b  is connected to a third flow path (gas flow path)  46  of the nozzle  4 . This enables supply of the gas G into the third flow path  46  as generally illustrated in  FIGS. 3 and 4 . 
     The insertion part  712  includes a groove  714  into which the edge of the flange  23  of each barrel  21  is inserted. 
     With the syringe holding part  71 , the opening part  22  of each barrel  21  is fitted into the fit part  711 , and the flange  23  of each barrel  21  is inserted into the insertion part  712  (groove  714 ). Thus, each barrel  21  is reliably held by the syringe holding part  71 . 
     The flange joint part  72  is a plate-shaped member interconnecting the flange  29  of the plunger  26  of the first syringe  2  and the flange  29  of the plunger  26  of the second syringe  3 . The flange joint part  72  includes a groove  721  into which the edge of the flange  29  of each plunger  26  is inserted or positioned. By pressing the flange joint part  72  toward the direction of the distal end, it is possible to move the respective plungers  26  of both syringes toward the distal end direction in one step (i.e., at the same time). Thus, the flange joint part  72  is an example of an operation part to be pressed and operated by a user when the sprayer  1  is used, i.e., the mixture is sprayed to the objective site such as the affected part. 
     As shown in  FIG. 1 , the nozzle  4  is set on the distal end side of the sprayer main body  7 . The nozzle  4  is configured to eject a mixture of the first liquid L 1  and the second liquid L 2  together with the gas G. The nozzle  4  includes an elongated nozzle main body  43 , and a nozzle head  42  having a larger diameter than the outer diameter of the nozzle main body  43 . 
     As shown in  FIGS. 2-6 , the nozzle main body  43  has a liquid flow path  41  including the first flow path  44  through which the first liquid L 1  fed from the first syringe  2  passes, and the second flow path  45  through which the second liquid L 2  fed from the second syringe  3  passes. Further, the nozzle main body  43  has the third flow path  46  through which the gas G fed from the gas cylinder  300   b  passes. 
     The first flow path  44  and the second flow path  45  which permit the passage of the respective liquids each include a bore or lumen defined by an inner tube. The proximal end of the inner tube forming the first flow path  44  extends to the position at which it is connected to the opening part  22  of the first syringe  2 . In a similar manner, the proximal end of the inner tube forming the second flow path  45  extends to the position at which it is connected to the opening part  22  of the second syringe  3 . 
     The distal end portions of the first flow path  44  and the second flow path  45  merge with each other. The distal end portions of the first and second flow paths  44 ,  45  merge together at a merge part  47 . In the illustrated embodiment, the merge part  47  is in the form of a tubular member. 
     The merge part  47  may be formed as extensions of the respective inner tubes. Alternatively, the merge part  47  may be formed of a tube body separate from the inner tubes as shown in  FIG. 2 . The distal end part  471  of the merge part  47  is fitted to the distal end inner circumferential part  461  of the outer tube forming the third flow path  46  which is described in more detail later. Further, the proximal end part  472  of the merge part  47  is fitted to distal end parts  441 ,  451  of the respective inner tubes forming the first flow path  44  and the second flow path  45 , respectively. As a result, the merge part  47  is supported and fixed at its opposite ends. 
     In the illustrated embodiment, the third flow path  46  through which the gas G passes is comprised of a gap defined by the inner tubes respectively forming the first flow path  44  and the second flow path  45 , and the outer tube surrounding the inner tubes (i.e., the outer tube situated on the outer circumferential side of the inner tubes). The proximal end part of the outer tube is connected to the tube  302   b  via the connection part  715  of the sprayer main body  7 . Further, the distal end of the outer tube is open, and serves as an ejection port  424  through which the liquid mixture, comprised of the mixed first liquid L 1  and the second liquid L 2  at the merge part  47 , is ejected together with the gas G. By virtue of the liquid mixture being ejected together with the gas G, the liquid mixture is atomized and is thus relatively uniformly sprayed to the objective site. The distal end portion  47  of the tubular merger part  47  is connected to and in fluid communication with the ejection port  424 . 
     Thus, the nozzle  4  is constructed as a double tube structure including two inner tubes and the outer tube. With this configuration, the inner tubes (the first flow path  44  and the second flow path  45 ) and the outer tube (the third flow path  46 ) are in parallel positional relation to each other. Thus, as described above, respective tubes can be preferably used as the flow paths. Examples of materials which can be used for forming respective tubes include polyvinyl chloride, polypropylene, polyamide, polyurethane, and polytetrafluoroethylene (PTFE) can be used. Such materials can also be used for the tube part forming the merge part  47 . 
     As shown in  FIGS. 2-6 , one small through hole or vent  475  is provided in the merge part  47 . This one small hole  475  serves as a vent penetrating through the tube wall of the merge part. Through the hole  475 , the gas G which has passed through the third flow path  46  can flow into the merge part  47 . Accordingly, the flowing gas G is ejected together with the liquid mixture (the first liquid L 1  and the second liquid L 2 ) through the ejection port  424  as generally shown in  FIG. 4 . As a result, the liquid mixture is rendered in an atomized form, and is sprayed to the affected part. Then, as shown in  FIG. 5 , also for stopping spraying of the liquid mixture, as described later, the gas G flows into the merge part  47  through the inflow hole  475  due to the residual pressure in the third flow path  46 . As a result, the residual liquid (liquid mixture) in the merge part  47  is reliably blown off externally from the ejection port  424 . This helps prevent the liquid mixture from remaining in the merge part  47 , thus preventing the occurrence of clogging in the ejection port  424  (nozzle  4 ) as shown in  FIG. 6 . 
     In the illustrated embodiment, the through hole  475  is preferably situated at a portion on the uppermost stream side of the merge part  47 . In this embodiment, the through hole  475  is situated at a portion slightly closer to the distal end side than the portion (the proximal end part  472 ) to which the distal end part  441  of the first flow path  44  and the distal end part  451  of the second flow path  45  of the merge part  47  are fitted. In other words, the through hole  475  is situated at a position spaced from the distal-most ends of the flow paths  44 ,  45 . As a result, the gas G can spread roughly throughout the merge part  47  through the hole  475  so that the residual liquid in the merge part  47  can be removed with more reliability upon stopping the spraying of the liquid mixture. This helps more reliably prevent clogging from occurring in the ejection port  424  (nozzle  4 ). 
     In the operational state shown in  FIG. 4 , i.e., when the liquid mixture is being ejected, the gas G which has flowed into the merge part  47  through the hole  475  forms microbubbles (air bubbles) in the liquid mixture passing through the merge part  47 . Due to the microbubbles, the liquid mixture is stirred in the process of passing through the merge part  47 . As a result, the first liquid L 1  and the second liquid L 2  are relatively uniformly and surely mixed with each other to form a liquid mixture which is then sprayed. When the viscosities of both the liquids are different from each other, the liquids are less likely to be a uniform liquid mixture merely by merging the liquids. However, as described above, the microbubbles exert a stirring action of stirring the first liquid L 1  and the second liquid L 2 , and promoting mixing of the two liquids. This results in a uniform liquid mixture. 
     In the illustrated embodiment, the through hole  475  is circular in shape. In such a case, the hole diameter of the hole  475  is preferably 0.1 to 1 mm, and more preferably 0.3 to 0.6 mm. This enables the gas G to be supplied in the proper amount into the merge part  47 . Accordingly, the liquid mixture ejected from the ejection port  424  is reliably rendered in an atomized form. Further, the liquid mixture can be relatively reliably pushed out of the merge part  47  after the stopping of spraying of the liquid mixture. Further, the gas G which has passed through the small hole  475  can relatively easily form microbubbles (air bubbles) in the liquid mixture. Accordingly, the stirring action is produced with relative ease and reliability. 
     A method is using the embodiment of the sprayer described above and illustrated in the drawing figures is described below with reference to  FIGS. 2-6 . 
     The first syringe  2  and the second syringe  3  contain or are filled with the first liquid L 1  and the second liquid L 2 , respectively, each in an amount necessary for being sprayed onto the affected part. In this operational state, as shown in  FIG. 2 , the first liquid L 1  has not been supplied to the first flow path  44 . Similarly, the second liquid L 2  has not yet been supplied to the second flow path  45 . Further, from the gas cylinder  300   b , the gas G can be supplied to the sprayer  1 . However, the closable valve (cock) for controlling supply/stopping of supply of the gas G with respect to the sprayer  1  is in a closed state. For this reason, the gas G is also not yet supplied to the third flow path  46 . Therefore, the liquid mixture is not yet ejected from the nozzle  4 . 
     Then, from the operational state shown in  FIG. 2 , the valve is rendered in an open state. The gas G is then supplied to the third flow path  46  via the tube  302   b . As a result, as shown in  FIG. 3 , the gas G flows into the merge part  47  via the small hole  475 , passes through the merge part  47 , and is ejected from the ejection port  424 . 
     Next, the operator or user presses the flange joint part  72  of the sprayer  1  so that the flange joint part  72  is operated in the direction of the arrow in  FIG. 1 . This operation of the flange joint part  72  causes the first liquid L 1  to be supplied to the first flow path  44  and the second liquid L 2  to be supplied to the second flow path  45  as illustrated in  FIG. 4 . 
     The continued operation (pressing or pushing) of the flange joint part  72  of the sprayer  1  causes the first liquid L 1  and the second liquid L 2  to flow into the merge part  47 , merge, and become mixed together. Also, the gas G continues to flow into the merge part  47  via the small hole  475  as described above. Then, from the ejection port  424 , the liquid mixture is ejected together with the gas G as indicated in  FIG. 4 . The liquid mixture is atomized by the gas G, ejected at a relatively high speed, and is sprayed onto the affected part. 
     After completion of spraying of a prescribed amount of the liquid mixture onto the affected part, the cock is rendered in a closed state again, and the pressing or pushing (operation) on the flange joint part  72  of the sprayer  1  is stopped. As a result, supply of the first liquid L 1  to the first flow path  44  is stopped, and supply of the second liquid L 2  to the second flow path  45  is stopped. 
     Further, the supply of gas G to the third flow path  46  is also stopped. However, the gas G continues to flow into the merge part  47  by virtue of the residual pressure in the third flow path  46 . As a result, in the merge part  47 , the liquid mixture is pushed out of the ejection port  424  by the gas G which has flowed in via the through hole  475  as depicted in  FIG. 5 . As a result, a distal end P 1  of the first liquid L 1  (i.e., the distal-most location of the first liquid L 1 ) is situated in the vicinity of the distal end part  441  of the first flow path  44 , and a distal end P 2  of the second liquid L 2  is situated in the vicinity of the distal end part  451  of the second flow path  45  (i.e., the distal-most location of the second liquid L 2 ). With such a configuration, the liquid mixture is prevented from remaining in the merge part  47 , particularly, in the vicinity of the ejection port  424 . Further, the liquid mixture is prevented from gelatinizing. This helps prevent clogging from occurring in the ejection port  424 . 
     Further, with a decrease in pressure in the third flow path  46 , the amount of gas G flowing into the merge part  47  also decreases. Finally, the flow of gas g is also stopped as shown in  FIG. 6 . 
     Thus, with this disclosed and illustrated embodiment of the sprayer  1 , clogging is prevented from occurring in the nozzle  4 . Therefore, the sprayer  1  can be used again at a later time for spraying onto the affected part. 
     Incidentally, after completion of spraying of a prescribed amount of the liquid mixture onto the affected part, as described above, the cock is rendered in a closed state again. However, the invention is not limited in this regard as the cock may also be left in an open state. 
       FIG. 7  illustrates the distal end part of the nozzle in a sprayer according to a second embodiment. 
     The following description of the second embodiment of the sprayer focuses primarily upon the differences between this second embodiment and the embodiment described above. Features associated with this second embodiment that are the same as those associated with the first embodiment are identified by common reference numerals and a detailed description of such features is not repeated. This embodiment is the same as the first embodiment except that the position at which each inflow hole is formed is different. 
     In the nozzle  4 A shown in  FIG. 7 , an inflow hole or vent  452  is formed in a part of the second flow path  45  at a position upstream of the merge part  47  of the liquid flow path  41 . The inflow hole  452  is situated in the vicinity of the distal end part  451  (the portion on the downstream side) of the second flow path  45 . 
     With such a configuration, the gas G passes through the inflow hole  452  and the distal end part  451  of the second flow path  45  sequentially, and flows into the merge part  47 . The gas G flowing into the merge part  47  can spread roughly throughout the merge part  47 . Accordingly, upon stoppage of the spraying of the liquid mixture, the residual solution in the merge part  47  can be removed with reliability. This can relatively reliably help prevent clogging from occurring in the ejection port  424  (nozzle  4 A). 
       FIG. 8  illustrates the distal end part of the nozzle in a sprayer according to a third embodiment. 
     The description below of the third embodiment of the sprayer focuses primarily upon the differences between this third embodiment and the embodiments described above. Features associated with this third embodiment that are the same as those associated with the embodiments described above are identified by common reference numerals and a detailed description of such features is not repeated. 
     This embodiment is the same as the second embodiment except that the number of inflow holes and the position at which each inflow hole is formed are different. 
     The nozzle  4 B shown in  FIG. 8  includes, in addition to the inflow hole or vent  452  in the second flow path  45 , an inflow hole or vent  442  formed in a part of the first flow path  44 . The inflow hole  442  is located on the upstream side of the merge part  47  of the liquid flow path  41 . The inflow hole  442  is disposed in the vicinity of the distal end part  441  (the portion on the downstream side) of the first flow path  44 . The inflow hole  442  is located along the first flow path  44  at a position symmetric to the location of the inflow hole  452  with respect to the axis of the nozzle  4 B. 
     With such a configuration, the gas G which has sequentially passed through the inflow hole  452 , and the distal end part  441  of the first flow path  44 , and the gas G which has sequentially passed through the inflow hole  452 , and the distal end part  451  of the second flow path  45  flow into the merge part  47 . For this reason, in the nozzle  4 B, the amount of the gas G to flow into the merge part  47  is larger than with the nozzle  4 A of the second embodiment. Therefore, upon stopping spraying of the liquid mixture, the residual liquid in the merge part  47  can be removed with more reliability. This can help more reliably prevent clogging from occurring in the ejection port  424  (nozzle  4 B). 
       FIG. 9  illustrates the distal end part of the nozzle in a sprayer according to a fourth embodiment. 
     The description below of this further embodiment of the sprayer focuses primarily upon the differences between this fourth embodiment and the embodiments described above. Features associated with this embodiment that are the same as those associated with the embodiments described above are identified by common reference numerals and a detailed description of such features is not repeated. 
     This fourth embodiment is the same as the first embodiment except that the number of inflow holes formed and the position at which each inflow hole is formed are different. 
     The nozzle  4 C shown in  FIG. 9  includes, in addition to the through hole (vent)  475  located in the merge part  47 , the inflow hole (vent)  452  formed in a part of the second flow path  45  on the upstream side of the merge part  47  of the liquid flow path  41 . The inflow hole  452  is situated in the vicinity of the distal end part  451  (the portion on the downstream side) of the second flow path  45 . 
     This embodiment of the sprayer is configured so that the gas G which has passed through the inflow hole  452  and the distal end part  451  of the second flow path  45  sequentially merges with the gas G flowing through the hole  475  at the merge part  47 . Thus, in this embodiment, the configuration of the nozzle  4 C results in a larger amount of gas G flowing into the merge part  47  than with the nozzle  4  of the first embodiment. Therefore, upon stopping the spraying of the liquid mixture, the residual liquid in the merge part  47  can be removed with more reliability. This can help further prevent clogging from occurring in the ejection port  424  (nozzle  4 C). 
     In this embodiment of the nozzle  4 C, the same inflow hole  442  as in the third embodiment may be formed in the first flow path  44  at a position on the upstream side of the merge part  47  of the liquid flow path  41 . 
       FIG. 10  illustrates the distal end part of the nozzle in a sprayer according to a further embodiment. 
     The description below of the fifth embodiment of the sprayer focuses primarily upon the differences between this embodiment and the embodiments described above. Features associated with this fifth embodiment that are the same as those associated with the embodiments described above are identified by common reference numerals and a detailed description of such features is not repeated. 
     This embodiment is the same as the first embodiment except for differences in the configuration of the liquid flow path. 
     With a nozzle  4 D shown in  FIG. 10 , the position of the open end  441   a  of the first flow path  44  (distal end part  441 ) facing the merge part  47  is situated closer to the distal end side than the position of the opening end  451   a  of the second flow path  45  (distal end part  451 ) facing the merge part  47 . Namely, the opening end  441   a  of the first flow path  44  and the opening end  451   a  of the second flow path  45  are formed at positions shifted from each other in the longitudinal direction of the nozzle  4 D. Thus, the distal-most end  441   a  of the first flow path  44  is positioned distally forward of the distal end  451   a  of the second flow path  45 . 
     As described above, when the spraying operation of the liquid mixture is performed, and the spraying operation is then stopped, the gas G which has flowed into the merge part  47  by the residual pressure can blow off the liquid mixture in the merge part  47  through the ejection port  424 . This helps prevent the liquid mixture from remaining in the merge part  47 . Accordingly, coagulation of the liquid mixture in the merge part  47  is avoided or prevented, thereby inhibiting or preventing clogging in the ejection port  424 . Further, in this embodiment, even when the first liquid L 1  involuntarily flows through the opening end  441   a  of the first flow path  44 , and the second liquid L 2  also involuntarily flows through the opening end  451   a  of the second flow path  45  into the merge part  47 , the flowing first liquid L 1  and the second liquid L 2  can be prevented from being mixed with reliability due to the positioning of the open ends  441   a ,  451   a  at positions shifted from each other along the longitudinal direction of the nozzle  4 D. As a result, coagulation of these two liquids in the merge part  47  is avoided or prevented so that clogging in the ejection port  424  does not occur. 
     In this illustrated embodiment, the small hole (vent)  475  is situated between the opening end  441   a  of the first flow path  44  and the opening end  451   a  of the second flow path  45  with respect to the longitudinal direction of the nozzle  4 D (liquid flow path  41 ) in the configuration shown. However, the sprayer is not limited to this positioning of the hole  475 . The small hole  475  may be situated closer to the proximal end side than the opening end  451   a  of the second flow path  45 . 
       FIG. 11  illustrates the distal end part of the nozzle in a sprayer according to a sixth embodiment. 
     The description below of this additional embodiment of the sprayer focuses primarily upon the differences between this sixth embodiment and the embodiments described above. Features associated with this embodiment that are the same as those associated with the embodiments described above are identified by common reference numerals and a detailed description of such features is not repeated. 
     This sixth embodiment is the same as the first embodiment except that the sprayer further includes a pressure adjusting means. 
     The nozzle  4 E shown in  FIG. 11  includes a side hole  462 . This side hole  462  is located in the outer circumferential part (wall) of the third flow path  46  (nozzle head  42 ). The side hole  462  penetrates through the outer circumferential part (wall) of the nozzle head  42 . A valve body  49  is set in the side hole  462 . The valve body  49  functions as a pressure adjusting means for adjusting the pressure in the third flow path  46 . The manner in which the valve body  49  is fixed in place is not particularly limited. However, examples may include a method by fitting as shown and a method by adhesion. 
     The valve body  49  is formed of an elastic body in the form of a disk, and forms a part of the wall part of the third flow path  46 . The valve body  49  includes a slit (through hole)  491  penetrating through the valve body  49  in the direction of thickness of the valve body. The valve body  49  is formed of an elastic material, and hence the slit  491  has self closing properties. Due to the self closing property, when spraying of the liquid mixture is not being performed, the slid  491  is closed. This brings the nozzle  4  into the state in which the inside of the third flow path  46  (nozzle  4 ) and the outside of the third flow path  46  are blocked from each other. In this operational state, the sterility in the third flow path  46  is maintained. When the pressure in the third flow path  46  exceeds a given value while spraying of the liquid mixture is being performed, the slit  491  is pressed under the pressure and is thus opened. This brings the nozzle  4 E into the operational state in which the inside of the third flow path  46  (nozzle  4 ) and the outside of the third flow path  46  communicate with each other via the opened slit  491 . In this operational state, a part of the gas G in the third flow path  46  flows out (is discharged) from the opened slit  491 . As a result, the pressure inside the third flow path  46  is reduced so that the pressure in the third flow path  46  is adjusted. In the nozzle  4 E, the opened slit  491  may also serve as a discharge hole (vent). 
     When the nozzle distal end of the sprayer  1  comes in contact with biological tissue, and the outlet is blocked, the gas G flowing into the merge part  47  via the small hole  475  may thrust back the first liquid L 1  in the first flow path  44  and the second liquid L 2  in the second flow path  45 . However, with the presence of the valve body  49 , the pressure in the third flow path  46  is adjusted, which can prevent such counterflow. 
     In the illustrated embodiment, the valve body  49  is in the shape of a disk. However, the invention is not limited in this regard. For example, a duckbill valve is also acceptable. 
       FIG. 12  illustrates the distal end part of the nozzle in a sprayer according to a seventh embodiment. 
     The description below of the seventh embodiment of the sprayer focuses primarily upon the differences between this embodiment and the embodiments described above. Features associated with this seventh embodiment that are the same as those associated with the embodiments described above are identified by common reference numerals and a detailed description of such features is not repeated. 
     This embodiment is the same as the first embodiment except that the shape of the inflow hole is different. 
     The embodiment of the nozzle  4 F shown in  FIG. 12  includes a small through hole (vent)  475  which is inclined so that the angle θ of the central axis  475   a  of the hole  475  with respect to the liquid flow direction in the merge part  47  (liquid flow path  41 ) forms an acute angle. As a result, the gas G flowing into the merge part via the angled through hole  475  can flow preferentially toward the ejection port  424 , i.e., toward the direction in which the liquid mixture is thrust outward or ejected. As a result, upon stopping spraying of the liquid mixture, the residual liquid in the merge part  47  can be more reliably removed. Accordingly, it is possible to more surely prevent clogging from occurring in the ejection port  424  (nozzle  4 F). 
     Further, the inner circumferential surface and the edge of the hole  475  are provided with a water repellent layer  476 . The water repellent layer  476  makes the liquid mixture in the merge part  47  less likely to flow into the third flow path  46  via the hole  475 . 
     The method for forming the water repellent layer  476  is not particularly limited. Examples may include a method in which a material having water repellency (e.g., polytetrafluoroethylene (PTFE)) is sprayed in the vicinity of the through hole  475 . 
       FIG. 13  illustrates the distal end part of the nozzle in a sprayer according to another embodiment. 
     The description below of this embodiment of the sprayer focuses primarily upon the differences between this embodiment and the embodiments described above. Features associated with this embodiment that are the same as those associated with the embodiments described above are identified by common reference numerals and a detailed description of such features is not repeated. 
     This embodiment is the same as the first embodiment except for differences in the configuration of the merge part. 
     The nozzle  4   i  shown in  FIG. 13  includes a tubular part  479  projecting in a tubular form and in a proximal direction from the proximal end part  472  of the merge part  47   i . Thus, the tubular part  479  projects in the upstream direction toward the proximal end side. The tubular part  479  includes a proximal end opening part  479   a  open into the third flow path  46 , and functions as a vent for allowing the gas G which has passed through the third flow path  46  to flow into the merge part  47   i.    
     Due to the presence of the tubular part  479  having this configuration, the gas G can flow into the merge part  47   i  via the tubular part  479 , and further the liquid mixture in the merge part  47   i  can be relatively reliably inhibited or prevented from involuntarily leaking in the third flow path  46 . 
     As an alternative to the arrangement shown in  FIG. 13 , the tubular part  479  may be connected to the gas cylinder  300   b.    
     The sprayer disclosed here has been described by way of various illustrated embodiments. However, respective parts forming the sprayer can be replaced with others capable of exerting the same or similar functions or operational attributes. Further, additional features may be added to the illustrated embodiments of the sprayer. 
     Further, it is within the disclosure here to combine disclosed features from different embodiments in the same sprayer. The sprayer may thus be a combination of two or more configurations (features) of the respective embodiments. 
     Further, the vent or through opening formed in the liquid flow path is not limited to the small hole. The vent or through hole may also take the form of a through slit. 
     Still further, in the inner surface of the merge part, spiral grooves may be formed. This promotes stirring of the liquids at the merge part. 
     The principles, embodiments and modes of operation of the sprayer disclosed here have been described in the foregoing specification, but the invention which is intended to be protected is not to be construed as limited to the particular embodiments disclosed. The embodiments described herein are to be regarded as illustrative rather than restrictive. Variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present invention. Accordingly, it is expressly intended that all such variations, changes and equivalents which fall within the spirit and scope of the present invention as defined in the claims, be embraced thereby.