Patent Publication Number: US-2018036480-A1

Title: Device for Administration of Fluid Medicaments

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is the U.S. national stage of International Application No. PCT/EP2015/000365, filed on 2015 Feb. 19. 
    
    
     BACKGROUND 
     The present invention relates to a device for the administration of fluids to a human or animal body, comprising a housing with a first inlet, at least one second inlet, one outlet and a collecting point, wherein the first inlet communicates with the collecting point through a first channel and the outlet communicates with the collecting point. 
     Such devices are known from prior art and serve the purpose of administering medicaments to humans, in particular infants, or, in some cases, to animals. There are some medicaments which need to be administered with a precise dose, as they have toxic properties and negative side effects. A patient should be exposed to such medicaments only as much as is necessary. Too high a dosage of such medicaments can cause serious damage to a patient and can even cause the death of the same. On the other hand, a dosage too low leads to an insufficient treatment of the respective medical indication, while nevertheless exposing the patient to such medicaments, and thus, causing negative side effects. 
     An apparatus for administering multiple fluid medicaments to a patient is known from U.S. Pat. No. 3,941,126 A. The apparatus allows for an independent adjustment of the dilution of the individual medicaments fed to it. The dilutor is fed from a storage vessel into cylindrical containers through valves, where the amount of the dilutor can be adjusted for each container. Subsequently, the medicaments are added to the individual containers with the aid of syringes. By means of additional valves the diluted medicaments flow into a drip chamber through separate tubes where they converge. The mixture of diluted medicaments then flows to a point of administration, e.g. an infusion needle, through another tube. 
     US 2009/0137951 A1 discloses an apparatus for transferring several fluid medicaments into a tube with several channels. The tube ends in a mixing chamber arranged in the proximity of a patient. The medicaments converge within the mixing chamber. The medicament mixture then flows from the mixing chamber to an administration point that can be embodied as an infusion needle, e.g. Thus, owing to the said tube featuring several channels, the medicaments converge shortly before the administration point. 
     SUMMARY 
     The present invention relates to a device  2  for the administration of fluids to a human or animal body comprising a housing  3  with a first inlet  28 , at least one second inlet  29 ,  30 , one outlet  31  and a collecting point, wherein the first inlet  28  communicates with the collecting point through a first channel and the outlet  31  communicates with the collecting point. The device is characterized in that the second inlet  29 ,  30  communicates with the collecting point or an indicator chamber  24 ,  25  through a second channel  21 ,  22  in which a valve  26 ,  27  is arranged, the valve  26 ,  27  being adjustable between a first position and a second position, wherein, in the first position of the valve  26 ,  27 , the second channel  26 ,  27  communicates with the indicator chamber  24 ,  25  and, in the second position of the valve  26 ,  27 , the second channel  21 ,  22  communicates with the collecting point. With the device  2  according to the invention, flow rate irregularities are eliminated (over shoot) or at least minimized (time delay, flow rate fluctuations due to changing flow rates), such that the device  2  allows for a more precise dosage. 
     DETAILED DESCRIPTION 
     It is an object of the present invention to provide a device for administering fluid medicaments to a patient with a more precise dosage with respect to devices known from prior art, especially with low flow rates in the range of 0.5 ml/h to 20 ml/h. 
     This is achieved by a device with the features of claim  1 . The device according to the invention is characterized in that the second inlet communicates with the collecting point or an indicator chamber through a second channel, in which a valve is arranged, while said valve is adjustable between a first position and a second position, wherein the second channel communicates with the indicator chamber in the first position of the valve, and the second channel communicates with the collecting point in the second position of the valve. 
     First of all, it should be noted that the expressions fluid and medicament are used interchangeably throughout the present description of the invention, since the medicaments that are to be administered to a patient by means of the device according to the invention are in the form of a fluid, i.e. fluid substances or solutions of originally solid substances. In the latter case, the solvent is in most cases water, which might already contain sodium chloride. Furthermore, a solution without a physiological effect on a patient, in particular a sodium chloride solution, can be fed to one of the inlets serving as a transportation medium for the medicaments which are to be administered and which are fed to the second inlet. Furthermore, a nutritive solution can be fed to the device. The fluids fed to the first and second inlets are collected in the collecting point that is therefore denominated as such. 
     In addition to the collecting point, the device comprises an indicator chamber whose purpose is to indicate, in particular making visible, that the flow path between the second inlet and the valve, including the volume of the valve which is exposed to the fluid fed to the second inlet, is filled with fluid. Once this is ensured, the valve is adjusted from its first position to its second position, in which the second channel communicates with the collecting point. Since the second channel and the fluid guiding volume of the valve is already filled with fluid, converging of the fluid fed to the second inlet and the fluid fed to the first inlet occurs immediately after the valve is switched in its second position, and thus, the delay between adjusting the valve and administering the mixture of fluids to a patient is minimized. This allows for a precise setting of the point in time at which the administration of medicaments starts and therefore, for a more precise calculation of the dose (dose=[volume of medicament/time unit]×administration period) actually administered to a patient. For these reasons, the indicator chamber is an essential feature of the device according to the invention. 
     When employing the device according to the invention, tubes are connected to the first inlet, to the at least one second inlet and to the outlet, respectively. The tube connected to the outlet is connected with an infusion needle on its proximal end. Then, pumps are activated feeding a first fluid to the first inlet through a first tube and a second fluid to the second inlet through a second tube. This first fluid is generally a sodium chloride solution or a nutritive solution. The second fluid is regularly a medicament. The valve of the device is in its first position and provides thus a fluid connection between the second inlet and the indicator chamber via the second channel. After a short while, the indicator chamber is filled with the second fluid which is at least detectable electronically, e.g. by means of a detector, but preferably visible. In the next step, the valve is adjusted to its second position, in which state the valve provides a fluid connection between the second inlet and the collecting point via the second channel. Now, the second fluid being fed through the second channel and the first fluid being fed through the first channel converge at the collecting point. The mixture of the fluids is then fed to the outlet communicating with the collecting point. If administration of the second fluid, normally a medicament, shall end, the valve is switched back to its first position so as to block the fluid connection between the second inlet and the collecting point. On the other hand, the fluid connection between the first inlet and the collecting point is still existent, and the first fluid, normally a sodium chloride solution or a nutritive solution, is still administered to the patient. The valve can later be adjusted to its second position again in order to further administer the second fluid to the patient if desired or necessary. In the latter case, there is again almost no delay between adjusting the valve and the administration of the second fluid, since the flow path is already filled with the second fluid. 
     It is pointed out, that a device comprising one first inlet and one second inlet is merely a basic embodiment of the device according to the invention. Preferably, there are two second inlets and, correspondingly, two second channels, two valves and two indicator chambers. However, more than two second inlets and, correspondingly, more than two second channels, two second valves and two indicator chambers can be provided as well. 
     Further advantageous embodiments of the device according to the invention result from the sub-claims. 
     According to such an advantageous embodiment, the indicator chamber and/or the housing is at least in part transparent or translucent for visible electromagnetic radiation, i.e. for visible light. This feature allows for a simple detection of whether the indicator chamber is filled with the fluid fed to the second inlet, namely by means of a human eye. 
     According to a further embodiment of the invention, the indicator chamber comprises a hydrophobic filter element. However, according to a preferred embodiment, the indicator chamber comprises an indicator element which changes its color in case of fluid contact. Obviously, there can be both a hydrophobic filter element and an indicator element arranged within the indicator chamber. A hydrophobic filter element allows air or gas bubbles to escape, which must not enter a patient&#39;s blood circuit. This is due to the well-known fact that air or other gases within the blood circuit can lead to a failure of the heard or other organs, since all organs need a blood supply for the supply with oxygen and nutritive substances. Blood also serves for temperature control of the organs and for the transport of products of metabolism. Correspondingly, the indicator chamber must comprise a wall with at least one opening communicating with the ambience air of the device and against which the hydrophobic filter element abuts in order to allow gas bubbles to escape. 
     A wall or a section of a wall of the indicator chamber, that is transparent for visible light, might already allow for the observation whether a fluid is present in the indicator chamber. However, according to a preferred embodiment, there is an indicator element arranged in the indicator chamber, which changes its color in case of fluid contact, such that the presence of a fluid in the indicator chamber is easily observable by the human eye and accordingly without further technical equipment. Of course, being observable by the human eye requires that a wall or a section of a wall of the indicator chamber is transparent or translucent for visible light. 
     The indicator element can be made of a sintered plastic material. Such a sintered plastic material combines the functionalities of a hydrophobic filter element on the one hand, and of an indicator element on the other hand. Such sintered plastic materials are porous before fluid contact and change their density in case of fluid contact, whereat the small channels of the previously porous plastic material get sealed. This might not be true for all plastic materials, but there are some plastic materials available which have this property in the sintered state. By means of at least one additive, a color transition in case of fluid contact can be achieved as well, in which case the indicator element serves as hydrophobic filter and as color changing indicator. Due to this synergy effect, the embodiment just described is the particularly preferred embodiment of the device according to the invention. A suitable plastic material having said property, i.e. the said synergy effect, is sintered polyethylene (PEL), which is already available on the market. 
     As is the case with the hydrophobic filter element, the indicator element with such a property abuts on a wall of the indicator chamber with at least one opening communicating with the ambience air of the device, in order to allow gas bubbles to escape from the indicator chamber and thus, from the fluid fed to the second inlet. 
     Furthermore, it can be provided that an inlet opening of the indicator chamber is covered by an elastic sealing element acting as a check valve which is closed in a pressureless state, whereat the term pressureless refers to atmospheric pressure, i.e. pressure not exceeding atmospheric pressure. The sealing element serves as a check valve and can be provided in addition to check valves arranged in the first or second channel or without the latter check valves. It covers the inlet opening of the indicator chamber, extends marginally over the circumference of the inlet opening and can be held in position by a support which contacts the sealing element in its center, for instance, and exerts an initial tension on the sealing element such that the outer edge of the sealing element acts as sealing lip being raisable in only one direction. 
     Such support can be realized in that the indicator chamber comprises at least one insertion element which holds the sealing element in its position by contacting the sealing element and/or which receives the hydrophobic filter element and/or the indicator element. The insertion element can serve both purposes or only one of them. Correspondingly, a plurality of insertion elements can be provided, which serve different purposes and are possibly fixed together by frictional connections, tongue and groove connections, welding, gluing or in similar ways. For example, the wall of the indicator chamber with at least one opening can be embodied as a wall element that is fixed on the insertion element or on one or more of the insertion elements. The housing of the device might comprise a clearance forming the indicator chamber and into which the at least one insertion element is, together with the sealing element and/or the hydrophobic filter element and/or the indicator element, inserted and fixed to the circumferential surface of the clearance by means of, e.g., a frictional connection, a tongue and groove connection, welding, gluing or the like. 
     As an alternative to the indicator element, an indicator mechanism can be arranged within the indicator chamber, comprising at least one movable part which moves with respect to the indicator chamber, preferably out of the same, when the latter is filled with fluid, i.e. the pressure within the indicator chamber leads to a movement of the movable part. Such indicator mechanism can be embodied as a pin, which is the movable part, and a resilient member, in the form of a spring, e.g. In this case, the pin moves against the restoring force of the resilient member due to the pressure within the indicator chamber, or the pin moves through the restoring force of the resilient member after the pressure within the indicator chamber has released a retainer that held the resilient member in a tensioned, i.e. compressed, state. Of course, a plurality of indicator mechanisms is conceivable by a skilled person and is considered to be within the scope of the present invention. The mentioned indicator mechanisms comprising a pin and a resilient member are merely chosen as an example. The indicator mechanism serves the same purpose as the indicator element referred to hereinbefore, namely, indicating wether the indicator chamber is filled with the fluid fed to the respective second channel. 
     The movable part can additionally feature a color mark, by means of which can be observed more easily that the movable part moved. 
     With a further embodiment of the device the second channel and/or the first channel comprise a filter chamber in which a hydrophilic filter member is arranged, wherein the filter member separates the filter chamber into to sub-chambers. This hydrophilic filter member allows for a removal of solid particles contained as contaminants in the medicament fed to the second inlet. Such contaminants can get into medicaments during the manufacturing process of the same, or by absorption from the air in non-decontaminated environments. However, they shall not reach the patient&#39;s blood, as agglomerates of such particles can block blood vessels or such particles can contain toxic ingredients like heavy metals. It is assumed that the hydrophilic filter members also contribute to an increased independency of flow rates within the single channels of the device, i.e. an adjustment of the flow rate within one channel has a lower effect on the flow rates within the other channels, since the hydrophilic filter members are flow resistances. 
     Furthermore, a hydrophobic filter member can be arranged in the filter chamber, which covers an opening of the filter chamber being in communication with the ambience air of the device. In this case, an opening is located in the filter chamber that communicates with the ambience air of the device, which means that the opening extends through the housing of the device. The opening is covered by the hydrophobic filter member allowing gas bubbles, in particular air bubbles, possibly contained in the fluid, which is fed to the second inlet, to escape. Air bubbles must be prevented from reaching the patient&#39;s blood circuit as set forth above. 
     The hydrophilic filter member and the hydrophobic filter member are preferably fixed to the filter chamber by welding, in particular ultra sonic welding, wherein the welding seam extends along the outer edge of the filter members. However, a fixation by means of gluing is also possible. 
     The hydrophilic filter member can be supported by protrusions extending from at least one wall of the filter chamber. The protrusions of this embodiment ensure that the hydrophilic filter member does not lose its flat shape. Moreover, the hydrophilic filter member can be fixed on some or all of the protrusions, in order to provide a stronger fixation of the hydrophilic filter member. 
     In order to prevent back flow of the fluids, a check valve can be arranged in the first channel and/or in the second channel. Preferably, one check valve is arranged in the first channel in the vicinity of the collecting point and one check valve is arranged in each second channel in the vicinity of the respective valve. 
     It is important that the dead volume of the device is comparatively small, since a larger dead volume leads to a longer delay between a switching of the valve and the administration of the fluid fed to the second inlet to a patient. It is assumed that the dead volume contributes to a dependency of flow rates, causing fluctuations of other flow rates if one flow rate is changed. It is assumed that a small dead volume minimizes this effect. The volume of the collecting point should therefore be small, which is why the denomination “collecting point” was chosen. However, the collecting point can be embodied as a collecting chamber with a larger dead volume due to design purposes, and in particular due to the fact that very small structural elements of the device lead to higher manufacturing costs, as it is difficult to manufacture small plastic components with the prescribed design, to assemble them and to fix them to each other by means of, for instance, welding or gluing. 
     In one particular embodiment the collecting chamber has a ring shape, i.e. a ring-like structure, whereat the fluids enter the collecting chamber at different points on its outer circumference. For instance, two second channels are provided, being arranged in the housing in such way that a second channel is positioned on each side of a centrally arranged first channel, whereat the second channels end in the ring-shaped collecting chamber at angle differences of +90° and −90° with respect to the end point of the first channel (0°). In this case, the exit point of the fluid or fluid mixture within the collecting chamber communicating with the outlet can be arranged opposite to the end point of the first channel, i.e. there is an angle difference of 180° between the end point of the first channel and the exit point of the collecting chamber. 
     Regarding the at least one valve of the device according to the invention, it can be provided that at least one section of the valve has a cylindrical shape, the radial surface of which comprises a recess extending over the circumference of the radial surface, wherein the recess provides a communication between the second channel and the indicator chamber in the first position of the valve, and between the second channel and the collecting point in the second position of the valve. By means of such a valve, the adjustment between the first and second position, and vice versa, can be carried out by turning its cylindrical section about the axial direction of the same. On the cylindrical section a grip portion can be formed, allowing for an easy manual adjustment of the valve. The cylindrical section of the valve can moreover be inserted into the housing, in which case there is a clearance formed within the housing of the device into which the cylindrical section of the valve is inserted and fixed in such a manner, that the cylindrical section is still turnable, e.g., by means of a tongue and groove connection. On the radial surface of the cylindrical section, a recess is formed that extends over the circumference of the radial surface allowing thus for an adjustable fluid connection between the second channel and the indicator chamber or the collecting point, whereat the adjustment can be conducted by turning the cylindrical section of the valve about its axial direction from the first position to the second position, or vice versa. The length of the recess formed on the radial surface of the cylindrical section depends on the angle difference between the location of the points of the second channel, which adjoin the cylindrical section and communicate with the second inlet, the collecting point or the indicator chamber. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A particular preferred embodiment of the device according to the invention is described hereinafter with reference to figures, whereat 
         FIG. 1  shows a perspective view of an infusion system comprising a preferred embodiment of the device according to the present invention, 
         FIG. 2  shows a sectional view of the preferred embodiment of the device, 
         FIG. 3  shows a further sectional view of the preferred embodiment of the device, 
         FIG. 4  shows a further sectional view of the preferred embodiment of the device, 
         FIG. 5  shows a perspective view of an insertion member being one component of the preferred embodiment of the device, 
         FIG. 6  shows a sectional view of the insertion member depicted in  FIG. 5 , 
         FIG. 7  shows a perspective view of a further insertion member being one component of the preferred embodiment of the device, 
         FIG. 8  shows a perspective view of a valve being one component of the preferred embodiment of the device, 
         FIG. 9  shows a sectional view of the valve depicted in  FIG. 8 , 
         FIG. 10  shows a perspective view of an insertion element being one component of the preferred embodiment of the device, 
         FIG. 11  shows a sectional view of the insertion element depicted in  FIG. 10 , 
         FIG. 12  depicts an exploded view of the preferred embodiment of the device, and 
         FIG. 13  shows a chart of measurement values of flow rates over time, measured both with a device according to prior art and with the preferred embodiment of the device according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows the preferred embodiment of the device  2  according to the invention in a perspective view, which is shown as a part of an infusion system  1 , and in more detail, in the following figures. The device  2  comprises a housing  3  to which tubes  4 ,  5 ,  6 ,  7  are connected. The tube  6  leads to the first inlet of the housing  3 , the tubes  5 ,  7  lead to a second inlet of the housing  3 , respectively, and the tube  4  is connected to the outlet of the housing  3  and leads to an external filter chamber  8  enclosing a hydrophobic filter. The external filter chamber  8  has an opening  9  formed in its housing such that gas bubbles can escape through the hydrophobic filter and the opening  9 . Such an external filter chamber  8  is already employed with state of the art infusion systems and is therefore not part of the present invention. The tube  10  leads to the patient. On the end portion of the tube  10 , a male connector  11  of a luer-lock-connection is attached. The connector  11  is connected to an infusion needle (not shown) during the use of the infusion system  1 . A female connector  12  of a luer-lock-connection is attached to the end portions of tubes  5 ,  6 ,  7 , respectively, allowing for a connection of the respective tube  5 ,  6 ,  7  to a medicament source or a pump driving medicaments to the respective tubes  5 ,  6 ,  7 . The device  2  comprises moreover two grip portions  13 ,  14 , to which is made reference hereinafter. 
       FIG. 2  shows a horizontal sectional view of the device  2 . The device comprises a housing  3 , in which a first channel  20 , two second channels  21 ,  22 , a collecting chamber  23 , two indicator chambers  24 ,  25  and two valves  26 ,  27  are arranged. The housing  3  further comprises a first inlet  28 , two second inlets  29 ,  30 , an outlet  31  communicating with the collecting chamber  23  through an outlet channel  32 , three check valves  33 ,  34 ,  35 , and two filter chambers  36 ,  37 . 
     The first channel  20  extends through the housing starting from the first inlet  28  and ending at the collecting chamber  23 . Within the first channel  28  check valve  33  is arranged in the vicinity of the collecting chamber  23 , preventing back flow from the collecting chamber  23  into the first channel  20 . 
     The collecting chamber  23  is essentially ring-shaped. There is a protrusion  38  formed on the inner wall of the ring-shaped collecting chamber  23 , which protrusion  38  extends marginally into the first channel  20 . The protrusion  38  results in the fluid fed to the first channel  20  being separated into two half streams, flowing through the collecting chamber  23  in different directions, i.e. clockwise and counterclockwise, when it enters the collecting chamber  23 . The end of outlet channel  32  and protrusion  38  have an angle difference of 180°. The collecting chamber  23  is realized by providing a clearance in the housing  3 , into which a cylindrical-shaped insertion member  64  with a recess  65  formed on its radial surface is inserted. The collecting chamber  23  is formed by the recess of insertion member  64  and the circumferential surface of the clearance. 
     The second channels  21 ,  22  extend through the housing  3 , starting from the second inlets  29 ,  30  and ending at the indicator chambers  24 ,  25 , or at the collecting chamber  23 . The second channels  21 ,  22  each have a branched structure, wherein one of the valves  26 ,  27  is arranged at the branching point such that an adjustable fluid connection between the second channels  21 ,  22  and the indicator chambers  24 ,  25  or between the second channels  21 ,  22  and the collecting chamber  23  can be provided there. In each second channel, one of the check valves  34 ,  35  is arranged preventing backflow from the collecting chamber  23  or the indicator chambers  24 ,  25  towards the second inlets  29 ,  30 . In order to minimize the dead volume of the device  2  the branches  39 ,  40 ,  41 ,  42  of the second channels  21 ,  22  are designed to be very short and extend merely through the walls separating the valves  26 ,  27  from the indicator chambers  24 ,  25  and the walls separating the valves  26 ,  27  from the collecting chamber  23 . The minimal thickness of these walls depend on the desired mechanical stability of the device  2 . The second channels  21 ,  22  further comprise filter chambers  36 ,  37 , in which a hydrophilic filter member (not shown) or, in the present embodiment, a respective hydrophobic filter member (not shown) are arranged. In the sectional view of  FIG. 2  the outlets  45 ,  46  of the filter chambers  36 ,  37  are shown, which are covered by said hydrophilic filter members. These hydrophilic filter members extend horizontally throughout the entire respective filter chambers  36 ,  37  in the present embodiment, such that the latter are separated into two sub-chambers, one of which communicates with the upstream portion of the respective second channel  21 ,  22  and one of which communicates with an outlet  45 ,  46  of the respective filter chamber  36 ,  37 . 
     Each of the valves  26 ,  27  comprise a cylindrical section. On the radial surface of the cylindrical sections a corresponding recess  43 ,  44  is formed. The recesses  43 ,  44  extend over the radial surface of the cylindrical sections of the valves  26 ,  27  in order to provide an adjustable fluid connection between the second channels  21 ,  22  and the indicator chambers  24 ,  25  (first position of the valves  26 ,  27 ) or the collecting chamber  23  (second position of the valves  26 ,  27 ), whereat the adjustment is carried out by turning the cylindrical sections about their axial directions, moving the recesses  43 ,  44  at the same time. The grip portions  13 ,  14  shown in  FIG. 1  are formed on the cylindrical sections. Each valve  26 ,  27  comprises therefore one of the grip portions  13 ,  14  and one cylindrical section extending into the housing  3 , whereat the cylindrical sections extend vertically into the housing  3  in the present embodiment. Clearances for receiving the cylindrical sections of the valves  26 ,  27  are provided in the housing  3 . 
     Indicator chambers  24 ,  25  communicate with the second channels  21 ,  22  in the first position of the valves  26 ,  27 , which is the starting adjustment during employment of the device  2 . The indicator chambers  24 ,  25  comprise each an inlet opening  50 ,  51 , a sealing element  52 ,  53 , an insertion element  54 ,  55 , a wall element  56 ,  57  with an opening  58 ,  59  and an indicator element  60 ,  61 . The inlet openings  50 ,  51  have a protruded edge against which the sealing elements  52 ,  53  rest. Sealing elements  52 ,  53  are supported by protrusions  62 ,  63  formed on the insertions elements  54 ,  55 . Protrusions  62 ,  63  exert an initial tension on sealing elements  52 ,  53  such that they seal inlet openings  50 ,  51  in a pressure-less state. The sealing elements  52 ,  53  can be fixed on the protrusions  62 ,  63 , by welding, gluing or the like, in order to simplify the assembly of the device  2  during manufacturing. The sealing elements  52 ,  53  act as check valves, as their outer edges can only be raised in the inflow direction. 
     The insertion elements  54 ,  55  are of cylindrical shape. They are each inserted into a corresponding clearance provided on the housing  3  and fixed on the circumferential surfaces of the clearance by, for instance, a frictional connection, tongue and groove connection, welding or gluing. The wall elements  56 ,  57  are adapted to the cross sectional shape of the insertion elements  54 ,  55  and are fixed on the wall elements  56 ,  57 . They, furthermore, are transparent or translucent for visible light. The insertion elements  54 ,  55  receive indicator elements  60 ,  61  which consist in the present embodiment of sintered polyethylene (PEL). Indicator elements  60 ,  61  abut on the wall elements  56 ,  57  and cover the openings  58 ,  59 . As mentioned hereinbefore, sintered polyethylene is a porous plastic material such that air can pass through it. However, if the material is in contact with a fluid, it gets densified to an impervious state. Therefore, the openings  58 ,  59  are sealed by indicator element  60 ,  61 , if a fluid enters the indicator chambers  24 ,  25  and gets in contact with indicator elements  60 ,  61 . So, the air located within the second channels  21 ,  22  before employment of the device  2  is driven to indicator chambers  24 ,  25  by the fluids entering the second inlets  29 ,  30  and escapes via the openings  58 ,  59 , provided that the valves  26 ,  27  are in their first positions. When the fluids reach the indicator elements  60 ,  61 , the latter are densified and seal openings  58 ,  59 . 
     Indicator elements  60 ,  61  furthermore feature the property of a change in colour in case of fluid contact, which property can be achieved by additives. This allows for an easy observation whether a fluid has reached not only the respective indicator chamber  24 ,  25 , but the indicator element  60 ,  61  as well, i.e. that the air contained in the second channel  21 ,  22  upstream the indicator element  60 ,  61  was removed, and that the second channel  21 ,  22  and the recess  43 ,  44  of the valve  26 ,  27  are filled with the fluid fed to the respective second inlet  29 ,  30 . If administration of the fluid fed to one of the second inlets  29 ,  30  is to be started, the respective valve  26 ,  27  is switched from its first position to its second position, in which the respective second channel  21 ,  22  communicates with the collecting chamber  23 . Switching of both valves  26 ,  27  can occur at the same time or at different points in time, depending on the administration schedule set for a patient. Due to the fact, that the respective second channel  21 ,  22  and the respective recess  43 ,  44  are already filled with fluid, the delay between switching of the valve  26 ,  27  and administration of the fluid to a patient is shortened, which allows for a more precise dosage. In the second positions of the valves  26 ,  27 , the fluids fed to the second inlets  29 ,  30  flow to the collecting chamber  23  via recesses  43 ,  44  and enter the collecting chamber  23  at locations with an angle difference with respect the protrusion  38  and thus, with respect to the end portion of the first channel  20 , of ±90°. The fluids fed to the second inlet  29 ,  30  converge with the fluid fed to the first inlet  28  at these locations. The mixture of said fluids flows from there to the outlet channel  32  and to the outlet  31  of the device  2 . 
     The check valves  33 ,  34 ,  35  comprise each a cylindrical body with a protruding edge on one side and an elastic cover being fixed on the other side and having a slit formed therein. The elastic cover is formed such that it is openable by a fluid flowing in the inflow direction and closable by fluid flowing in the outflow direction. The protruding edge rests against a corresponding contact surface of the housing  3  to which the protruding edge can be fixed, e.g., by means of welding or gluing. 
       FIG. 3  shows a sectional view of the present embodiment of the device  2 , whereat one half of a vertical section through the first channel  20  is shown. A check valve  33  is arranged within a first channel  20  in the vicinity of collecting chamber  23 . The collecting chamber  23  is formed by the circumferential surface of a clearance provided in the housing  3  and a recess  65  on the radial surface of an insertion member  64 . The insertion member  64  is inserted into said clearance and fixed there by means of, for instance, a frictional connection, welding or gluing. Furthermore,  FIG. 3  shows an outlet  31 , an outlet channel  32  communicating with the collecting chamber  23  and a valve  27  with a grip portion  14 . Moreover, it is shown that the device  2  has a hollow structure, while the channels and sections necessary for the intended functionality are formed by walls of a particular thickness and the rest of the housing  3  is hollow. 
       FIG. 3  shows a sectional view of the present embodiment of the device  2 , whereat the other half of a vertical section through the first channel  20  is shown. A second channel  22  leads at first from a second inlet  30  to a filter chamber  37 . Within the filter chamber  37 , a hydrophilic filter member  70  and a hydrophobic filter member  71  are arranged, whereat hydrophilic filter member  70  extends horizontally throughout the entire filter chamber  37  separating thus the filter chamber  37  into two sub-chambers. The filter member  70  is welded or glued with its outer edge to a corresponding contact surface of the housing. The hydrophobic filter member  71  covers an opening  72  arranged in the housing  3 , and is fixed on the surface of the filter chamber  37  that surrounds the opening  72  by, for example, welding or gluing. The opening  72  communicates with the ambience air of the device  2 . The hydrophobic filter  71  and the opening  72  allow gas bubbles to escape from the fluid fed through second channel  22 . Moreover, air contained within second channels  22  upstream the filter chamber  37  can escape through the hydrophobic filter member  71  and the opening  72 . The filter chamber  37  is delimited partly by an insertion member  76 , which is essentially cylindrical-shaped. An insertion member  76  has a protruding edge  77  on its one side, which allows for a defined positioning of the insertion member  76  during the assembly of the device and, moreover, which provides a contact surface for the fixation of the insertion member  76  on the housing  3 , for instance, by welding or gluing. 
     The upper sub-chamber of the filter chamber  37  communicates with the downstream portion of the second channel  22  via an outlet  46 , which is formed on the insertion member  76 . Within the downstream portion of the second channel  22 , a check valve  35  is arranged. Downstream the check valve  35 , the second channel  22  leads to a recess  44  located on the radial surface of the cylindrical section  73  of the valve  27 . The valve  27  is fixed on the housing by means of a tongue  74  and groove  75  connection, whereat the groove  75  is formed on the radial surface of the cylindrical section  73 . By means of the grip portion  14 , the valve  27  is manually turnable in an easy manner. The lower sub-chamber of the filter chamber  37  communicates with the second inlet  30 . 
       FIG. 5  shows the insertion member  76 . The insertion member  76  has a substantially cylindrical shape and comprises a protruding edge  77  on one side and protrusions  80  on the frontal surface of the other side. The protrusions  80  support the hydrophilic filter member  70  and can be fixed on it, e.g., by welding or gluing. Furthermore, the outlet  46  is formed on the insertion member  76 . 
       FIG. 6  shows a vertical section view of the insertion member  76 . Protrusions  80  are formed on its frontal surface, and a protruding edge  77  on its other side. The outlet  46  extends from said frontal surface to the cylindrical-shaped radial surface of the insertion member  76 . 
       FIG. 7  shows the insertion member  64  by means of which the collecting chamber  23  is realized. The insertion member  64  has a cylindrical shape, whereat on its radial surface a recess  65  is formed, which extends almost along its entire circumference. Between the two ends of the recess  65 , a protrusion  38  is located and serves the purpose of splitting the fluid flow fed to the first channel  20 , as previously described. The insertion member  64  is inserted into a corresponding clearance of the housing  3  during the assembly of device  2 . 
       FIG. 8  depicts valve  27  in a perspective view. The structure of valve  27  is mirrored symmetrically to the structure of valve  26 , in case the grip portions  13 ,  14  are oriented parallely in their first and second positions. Valve  27  comprises a cylindrical section with a recess  44  on its radial surface. Recess  44  provides a fluid connection between the second channel  22  and the indicator chamber  25  or collecting chamber  23 , depending on whether valve  27  is in its first position or its second position. Adjustment between both positions can be carried out by turning the grip portion  14  about the axial direction of the cylindrical section and changing its orientation by 90°. 
       FIG. 9  shows valve  27  in a vertical section view. The grip portion  14 , a part of the recess  44  and the groove  75  are shown. By means of the groove  75  and the corresponding tongue  74 , the valve  27  is turnably and imperviously fixed on the housing  3 . 
       FIG. 10  shows the insertion element  55  of the indicator chamber  25 , which is identical to the insertion element  54  of the indicator chamber  24 , in a perspective view. It is of cylindrical shape and comprises a protrusion  63  and openings  90 , through which the fluid flowing into the indicator chamber  25  passes the insertion element  55  and reaches indicator element  61 . The sealing element  53  rests against the protrusion  63  such that only the outer edge of the sealing element  53  is raisable in order to allow fluid to enter the collecting chamber  25 . 
       FIG. 11  shows the insertion element  55  in a vertical section view. Openings  90  and a protrusion  63  are shown. The inner space  91  of the insertion element  55  receives the indicator element  61 , and can additionally receive a separate hydrophobic filter element. 
       FIG. 12  shows an exploded perspective view of the present embodiment of device  2 . Next to the components described above, a hydrophilic filter member  100 , a hydrophobic filter member  101 , an insertion member  102  and housing elements  103 ,  104 ,  105 ,  106  are shown. The filter members  100 ,  101  are the equivalents of filter members  70 ,  71  and are arranged in the filter chamber  36  comprised by the second channel  21 . The insertion member  102  is the equivalent of the insertion member  76 . Housing elements  103 ,  104 ,  105 ,  106  constitute the housing  3 . The housing elements  103 ,  104 ,  105 ,  106  are designed such that they are as few as possible in number and allow for an easy assembly of all components of the device  2 . When assembling the device  2 , check valves  33 ,  34 ,  35  are arranged in their final positions and fixed on the housing element  103  with their protruding edges by, for example, a frictional connection, a tongue and groove connection, welding, in particular ultra sonic welding, or gluing. Then, the housing element  103  and the housing element  104  are plugged together and fixed to one another by, for example, a frictional connection, a tongue and groove connection, welding, in particular ultra sonic welding, or gluing. Then, all other components, except valves  26 ,  27  and housing element  104 , are arranged in their respective final positions and fixed there by, for example, a frictional connection, a tongue and groove connection, welding, in particular ultra sonic welding, or gluing. Then, the housing element  105  is fixed on housing elements  103 ,  104 , by, for example, a frictional connection, a tongue and groove connection, welding, in particular ultra sonic welding, or gluing. Finally, the valves  26 ,  27  are inserted into the corresponding clearances of housing elements  103 ,  105  and fixed there by means of the said tongue and groove connection (see description of  FIGS. 4 and 9 ). 
       FIG. 13  shows a chart of measurement values of flow rates  110 ,  111  taken with the preferred embodiment of device  2  as shown in  FIGS. 1 to 12 , and measurement values of flow rates  112 ,  113  taken with an infusion system according to prior art, by means of which several fluids converge and are fed to a patient as mixture through a single tube. The dashed lines  114 ,  115  show the pump settings of pumps that drive the fluids through the first  20  and one of the second 21, 22 channels. One pump is allocated to each tube leading to device  2 , so as to independently adjust the flow rates. The dashed line  114  shows the pump setting of the pump connected to the first inlet  28 , whereas the dashed line  115  shows the setting of the pump connected to one of the second inlets  29 ,  30 . A sodium chloride solution or nutritive solution will generally be fed through the first channel  20 , whereas medicaments will normally be fed through the second channels  21 ,  22 . Therefore, the flow rate of the fluid fed through the first channel  20  usually amounts to between 6 ml/h and 12 ml/h, whereas the flow rate of the fluids fed through the second channels  21 ,  22 , amounts to between 0.5 ml/h and 2 ml/h. The pressure within the fluid guiding parts of the device  2  and the tubes leading to it typically amounts to 2 bar to 3 bar. 
     Referring to  FIG. 13 , there are three effects observable with prior art infusion systems. First, the delay between activation of the pumps occurring at  0  on the x-axis of  FIG. 13  and administration of the fluids, i.e. the point in time at which the fluids have reached at least the connector  11  ( FIG. 1 ). The delay is noticeably shorter with the device according to the invention. This is due to the fact that the infusion system  1  comprising the device  2  is already filled up to the valves  26 ,  27 , including the recesses  43 ,  44 . If the administration of a medicament is to be initiated, the corresponding valve is turned from its first position to its second position, whereat the remaining length of the flow path, i.e. the length of the flow path between valves  26 ,  27  and the connector  11 , is shorter. So, the reference time serving as a basis for the dose calculation is closer to the point in time at which administration actually starts. The presence of fluids in the indicator chambers  24 ,  25  is easily observable thanks to the indicator elements  60 , 61  changing their colour in case of fluid contact, and the wall elements  56 , 57  being transparent or translucent for visible light. 
     A second effect observable with prior art infusion systems is the so-called over shoot occurring with the flow rate  112  between 0.5 h and 1 h and between 3.25 h and 3.5 h. This problem is remedied with the device  2 , as can be seen on the course of flow rate  110 . 
     A third effect observable with prior art infusion systems are flow rate fluctuations occurring if one of two or more flow rates is set to another value by means of a pump. Such fluctuations occur with the flow rate  112  between 5.0 h and 5.25 h, where the pump setting is set from 0.5 ml/h to 1.0 ml/h, and between 6.0 h and 6.25 h, where the pump setting  115  is set from 1.0 ml/h to 0.5 ml/h. With the flow rate  113  such fluctuations occur between 3.0 h and 3.25 h, where the pump setting  114  is set from 6.0 ml/h to 10 ml/h, and between 4.0 and 4.25 h, where the pump setting  114  is set from 10 ml/h to 6 ml/h. These fluctuations are remarkably minimized with the device  2 , as can be seen on the course of flow rates  110 ,  111 . 
     The courses of flow rates  110 ,  111  are in general remarkably closer to the courses of the respective pump settings  114 ,  115 , i.e. a more precise dosage is achieved. 
     While the invention has been described with reference to a specific embodiment, the description is merely explanatory and is not to be construed as limiting the scope of the invention. Various modifications may be conceived by those skilled in the art without departing from the scope of the invention as defined by the claims. 
     LIST OF REFERENCE NUMERALS 
     
         
           1  infusion system 
           2  device 
           3  housing 
           4  tube 
           5  tube 
           6  tube 
           7  tube 
           8  external filter chamber 
           9  opening 
           10  tube 
           11  male connector 
           12  female connector 
           13  grip portion 
           14  grip portion 
           20  first channel 
           21  second channel 
           22  second channel 
           23  collecting chamber 
           24  indicator chamber 
           25  indicator chamber 
           26  valve 
           27  valve 
           28  first inlet 
           29  second inlet 
           30  second inlet 
           31  outlet 
           32  outlet channel 
           33  check valve 
           34  check valve 
           35  check valve 
           36  filter chamber 
           37  filter chamber 
           38  protrusion 
           39  branch 
           40  branch 
           41  branch 
           42  branch 
           43  recess 
           44  recess 
           45  outlet 
           46  outlet 
           50  inlet opening 
           51  inlet opening 
           52  sealing element 
           53  sealing element 
           54  insertion element 
           55  insertion element 
           56  wall element 
           57  wall element 
           58  opening 
           59  opening 
           60  indicator element 
           61  indicator element 
           62  protrusion 
           63  protrusion 
           64  insertion member 
           65  recess 
           70  hydrophilic filter member 
           71  hydrophobic filter member 
           72  opening 
           73  cylindrical section 
           74  tongue 
           75  groove 
           76  insertion member 
           77  protruding edge 
           80  protrusions 
           90  openings 
           91  inner space 
           100  hydrophilic filter member 
           101  hydrophobic filter member 
           102  insertion member 
           103  housing element 
           104  housing element 
           105  housing element 
           106  housing element 
           110  flow rate over time 
           111  flow rate over time 
           112  flow rate over time 
           113  flow rate over time 
           114  pump setting over time 
           115  pump setting over time