DK153593B - APPARATUS FOR MANAGEMENT OF LIQUID FLOWS, IN PARTICULAR BY INTRAVENOES ADMINSTRATION OF LIQUID - Google Patents

Description

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DK 153593B

The present invention relates to an apparatus for controlling fluid flow, especially in the intravenous administration of fluid, and is of the kind set forth in the preamble of claim 1.

A known intravenous delivery device contains a liquid container to be administered, a tube connected to the container, a hollow needle or cannula at the end of the tube and to be inserted into a patient's vein, and a device for controlling the amount of fluid. which, under the influence of gravity, flows out of the container and into the hollow needle. This system is known as a gravity system. For use, the container, such as a bottle or plastic bag filled with liquid, is connected to the hollow needle or cannula which is inserted into the vein by the flexible tube.

The container is placed at a certain height above the patient. The liquid flow is adjusted by means of the control device in the form of an adjustable clamp on the flexible supply pipe containing a droplet chamber to give an indication of the rate at which the liquid is being administered.

Gravity systems are used for infusion as well as transfusion. In the case of infusion, fluids such as glucose and saline solutions to which medications may be added are administered. During transfusions, on the other hand, blood is administered. There is no major difference in the administration technique, and unless otherwise indicated, the term infusion is to be construed as including transfusion in the following.

The duration of continuous infusion administration may vary from a few hours to a few days, or even longer. The amount of fluid administered per unit of time is important, especially when certain medications are added to the infusion liquid.

In connection with existing gravity systems, the amount of fluid administered per time unit not very stable due to the operating principle and arrangement of these systems. The main causes of variations in the set flow rate or flow rate are changes in: a) the flow resistance in the tube around the setting 2;

DK 153593B

the clamp and in the hollow needle or cannula of the vein, b) the resistance to outflow at the needle end, c) the height of the fluid column in the aditiiiiisfeifafeioflssysfeenisfc, and d) the blood pressure in the vein at the insertion site.

05 Gravity systems require that the nursing staff perform continuous monitoring to control and adjust the flow rate and to make timely replacement of the fluid container to prevent air from entering the control system when the container becomes empty.

10 More specifically, the causes of the aforementioned variations in the set flow rate or flow rate are as follows: a) In the gravity system there are two significant flow resistances, one near the adjusting terminal of the tube and the other in the hollow needle. A third significant flow resistance may be present when a microfilter is included.

The flow area around the control device is dependent on the setting of the device and has a value between 0 and approx. 0.1 mm2. The shape of the flow area in this region 20 of the flow path is an elongated or circular slit with an average aperture of the order of some microns. Infusion fluids may contain very small solid components that may cause clogging or deposits in the control orifice, thereby reducing the flow of quantities. When a filter is used, the same effect may occur with the filter.

Partial obstruction of the needle or cannula may also occur, especially if the infusion of infusion fluid is too slow or if there is a backflow of blood.

Another reason may be an accidental resetting or adjustment of the control device. Some systems use a roller clamp, while other systems use a bending clamp, which provides a sharp-edged bend in the tube. External causes, such as the patient's movements, or the viscoelastic properties of the tubular material, may cause the gap opening to vary.

DK 153593B

3 b) The hollow needle or cannula inserted into the vein has an obliquely cut end, hence the outflow opening is elliptical. The surface of the ocular flow opening is positioned at an acute angle to the vein wall. The patient's movements 05 may cause the outflow opening to be restricted or narrowed by the friend's wall.

c) The height of the liquid column in the gravity system affects the flow rate or flow rate. A change in the height of the fluid column is caused by the decreasing amount of fluid in the container and by any change in the patient's position. The height of the liquid column is determined by the level at which the static pressure in the system above the control clamp is equal to the atmospheric pressure as well as the relative height of the outlet opening 1 of the needle or cannula.

The effect of a drop in the liquid level in the container is maximal when using a plastic bag or bottle of the type in which air is supplied through an air hose and which has a rubber stopper provided internally with an air tube extending to a position. above the liquid level with the bottle 20 turned upside down.

If the interface between the supplied air and the liquid in the system is above the liquid level in the container, the effect of the falling liquid level is small as the pressure over the liquid decreases as the liquid level in the bottle falls.

The maximum pressure variation that can result from a drop in the liquid level in a bottle or bag containing a content of 500 cm 2 is approx. 15 cm water column, while the pressure variation that may result from a change in the patient's position is approx.

35 cm water column. Thus, the total possible pressure variation is 30 approx. 50 cm water column.

The change in the height of the liquid column can amount to approx. 50 cm water column. As a result, the fluid pressure can decrease 33 -50% with an initial height of 100 - 150 cm, resulting in a considerable reduction in the flow of fluid.

35 d) The venous blood pressure is 0 - 5 cm water column. Any variation has a minor influence on the flow of liquid. When 4

DK 153593B

however, if a child cries, the peripheral venous pressure may assume peak values of 100 cm of water column. The average value of the backpressure can therefore vary greatly. Furthermore, the administration system may be clogged by the blood flow back into the gravity system.

The object of the invention is to provide an apparatus which avoids the above-mentioned disadvantages. This is achieved by arranging the apparatus mentioned in the preamble as set forth in the characterizing part of claim 1.

The apparatus of the invention allows for the flow of fluid to be set and the apparatus automatically maintains the set value within narrow limits. Furthermore, the apparatus according to the invention functions such that the liquid flow is automatically switched off when the liquid pressure in the storage chamber 15 becomes too low, for example when a storage container is empty, the pressure of the first membrane being insufficient to keep the membrane free of the passage between the storage chamber and the filter chamber. This is important if the liquid supply is to be continued while the empty container needs to be replaced.

20 The automatic closure prevents air from being introduced into the system as it remains full of liquid. An empty container can be replaced for some time after the liquid has stopped flowing from the container, which simplifies the control and replacement of liquid containers.

In a preferred embodiment, an opening in line with an outlet end for the inlet duct is arranged in a wall of the council chamber which is on the opposite side of the first diaphragm relative to the inlet chamber and an element can be inserted into this opening for the purpose of to press the first 30 diaphragm against the outlet end of the inlet channel, which is thereby closed.

The element in question may be a tap or a remote controlled push button. Further, the element may be a pneumatic tube which can be connected to the opening and by means of which the membrane can be pressed against the passage between the storage chamber 35 and the filter chamber by means of compressed air.

The apparatus according to the invention preferably contains

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5 supply channels having separate outlet ends as well as a corresponding number of openings in the opposite wall of the storage chamber, and elements may be inserted into these openings to selectively open and close the inlet channels. This allows for a similar number of liquid containers to be connected simultaneously with the apparatus of the invention, and these containers may contain the same liquid so that an extended fluid supply is possible without replacement of the containers or the containers may contain different liquids for a liquid mixture. 10 to be added.

In the preferred embodiment, a wall of the storage chamber which is on the opposite side of the membrane relative to the passage between the storage chamber and the filter chamber has an opening in line with the passage and into which an element can be inserted for pressing the first membrane into in and thereby close the passage.

When the outlet openings for the inlet ducts are open and when the passage between the supply chamber and the filter chamber is closed, the supply duct forms a system of connected containers which can be used for mixing or measuring quantities of liquids. The element in question may be hand-operated, but may also be operated by a remote control system which may be simply designed. The special advantage is that the element does not come into contact with the liquid, so that no connections must be disconnected and the sterile liquid circuit is not pierced. The element in question may be arranged as indicated above. When a pneumatic tube is used, a pulsating pressure can be exerted on the first diaphragm so that the diaphragm can act as a pump.

The control devices in the apparatus according to the invention preferably contain a cylindrical body which can be rotated about its axis and which has a groove extending around a portion of the circumference, the bottom of which groove extending along a circular arc which is eccentric relative to to the axis of the body, 35 and the depth of the groove increases from 0 at one end to 0.5 mm at the other end.

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This allows for reliable and simply adjustable flow control. The groove is preferably V-shaped in cross-section, so that the relationship between the flow area and its outline is as favorable as possible in all positions of the cylindrical body. The optimum shape of the flow area would be a circle, but an approximation thereof is a triangle, preferably at an angle of 90 °.

That is, all known controllers have an elongated or circular flow control slot. For example, when the flow area is 0.1 mm 2, the opening of this gap is so small (0.01 mm or less) that solid particles in the liquid will lead to partial clogging of the gap and the flow is disturbed.

An advantage of the preferred embodiment of the invention is that the passage for solid components is at least 10 times greater than in other known constructions.

Seen in a transverse plane of the cylindrical body, the groove is semicircular with the center lying eccentric relative to the axis of the cylindrical body. In experiments, it has been found that the flow resistance changes exponentially with the rotation of the cylindrical body, thereby allowing a very accurate control of the flow.

Certain regulations require that flow control devices allow for a certain amount of fluid to flow through per unit of fluid. unit of time (see, for example, British Standard 2463, 1962, paragraph 33). To meet this requirement, it is preferred that the cylindrical body at one end of the groove where this is deepest is provided with a second groove, which groove has a flow area at least equal to the by-pass channel flow area. .

The apparatus described can be used in areas other than administering fluids to patients. In fact, the apparatus according to the invention can also be used for any application where small amounts of a liquid are to be delivered at fixed rates, for example in connection with chemical processes.

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7 preparation of drinking water, etc.

With the described control device, the following benefits can be obtained when the device is used in a transfusion or infusion set: 05 a) A labor saving for the nursing staff, especially as the time between fluid reservoir replacement can be 200% of the time associated with known devices, b) an improved and (c) an increase in the technical capabilities of intravenous therapy while maintaining the possibility of using a single-use administration system. The effect of connecting a remote control system is limited to inserting pin-shaped elements into the above-mentioned openings in the side of the storage chamber facing away from the filter. The ability to independently control the fluid connections in combination with a constant amount of fluid flow makes it possible to produce a mixture of a number of liquids or liquid compositions in the process itself. This is done by controlling each of the connections in a cyclic order at different times and for short periods of time. Hereby any mixing ratio can be obtained. The mixing ratio can be constant or variable (using a program). A patient feedback system is also conceivable from a technical point of view.

In the following, the present invention will be explained in more detail with reference to the drawing, in which: 1 is a front view of an apparatus according to the invention; FIG. 2 shows the apparatus from the rear with a cover for the filter chamber removed and with the filter only partially shown; FIG. 3 is a sectional view taken along line III-III of FIG.

1, FIG. 4 is a section taken along the line IV-IV of FIG. 1, and FIG. 5 is an end view of the apparatus.

The apparatus shown in the drawing consists of two in the main case 8

DK 153593B

rectangular parts (having dimensions in the range of about 2.5 x 5 cm), namely a housing 1 and a cover plate 2, between which is inserted a rubber film 3 having a thickness of 0.30 mm. The housing 1 and the cover plate 2 are clamped by means of screws 4, which fit 05 through openings in the rubber film, which seal between edges 5 of the housing and the cover plate, and which form two membranes 6 and 7.

The housing 1 has three supply channels 8 with outlet openings 9 connected to a storage chamber 10 and a filter chamber 11. A filter element 12 is arranged in the chamber 11 which is closed by a removable filter cover 13, which allows the filter element to be easily renewed or replaced. .

Between the storage chamber 10 and the filter chamber 11 there is a passage 14 with a projecting rim 15, and a passage 16 connects an outlet chamber 17 with the filter chamber 11.

The cover plate 2 is provided with openings 18 which face the outlet openings 9 for the supply ducts 8. In each of these openings, an element, such as a pin 19, can be inserted for closing the associated outlet opening partially or completely by pressing the membrane 6 into the the outlet opening 9, for example in the position a, where the outlet opening 9 is completely closed. The cover plate 2 also has an opening 20 which is opposite the passage 14 between the storage chamber 10 and the filter chamber 11, and in this opening an element can also be inserted to press the diaphragm 6 into position a to completely close the passage 25 14.

In a resting position b, the diaphragm 6 abuts against the edge 15 under a certain tensile stress, and when liquid pressurized (about 10-15 cm water column) is fed through a supply duct 8, the diaphragm 6 is moved to position c. 14 and into the filter chamber 11 as indicated by arrow 21, along channels formed by ribs 11a and through the filter 12 as indicated by arrows 22, into grooves formed by ribs 23 on the filter cover 13 and finally into a groove 27, in which two passages 16 and 28 end.

The outlet chamber 17 contains the diaphragm 7 which, in the resting state, is in the position 25 indicated by a

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9 is a dotted line, wherein the outlet chamber is divided into a closed portion 17a and the portion 17b to which an outlet channel 30 is connected.

As indicated in FIG. 4, the groove 27 is connected to the portion 05 17a of the chamber 17 by means of the passage 16 and to the portion 17b of the chamber 17 by means of the passage 28, an opening 26 of the rubber film and a by-pass channel 31a, 31b.

A rim 31 is formed around the outlet opening 30.

When the pressure in the liquid flowing out of the filter chamber 10 is greater than the pressure in the outlet duct 30, the diaphragm 7 moves toward the rim 31 and the diaphragm closes duct 30 in whole or in part.

A control arrangement 29 divides the by-pass channel into two parts 31a and 31b, which are bounded in a housing 32, in which a cylindrical pin 33 is sealed tightly. The pin 33 has a groove 34 extending over a portion of the circumference in a plane perpendicular to the tap axis, and the bottom of the groove describes a circular arc whose center 35 is eccentric to the center 36 of the circular cross section of the pin 33. The cross section of the groove is triangular , Preferably at a top angle of 90 °. A further groove 37 is arranged in the pin and is connected to the groove 34 at its deepest end.

The liquid flowing out of the filter chamber, as indicated by an arrow 24, is divided into two parts (arrows 38 and 39). The one part (arrow 38) flows to the outlet channel 30 (arrows 40), while the other part (arrow 39) exerts pressure on the side of the diaphragm 7 which is furthest from the outlet channel 30.

Track 37 ensures that a certain amount of fluid will flow in through. time unit, as required by British Standard 2463, 30 1962, paragraph 33. A similar requirement also applies in various other countries.

An adjustment of the groove 34 relative to the by-pass channel portion 31b is achieved by an arm 41 which is attached to the pin 33 and which is rotatable as indicated by an arrow 42.

35 This setting changes the flow of liquid through the device.

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10

One or more ducts 8 are connected to liquid containers by flexible tubes. The outlet duct 30 is connected to a further flexible tube, the other end of which is provided with a hollow needle or needle which can be inserted into the vein of a person to whom the fluid is to be administered. A further drip chamber is inserted in this further tube.

The liquid flowing to the supply channel 8 displaces the membrane 6 from position b to position c if the pressure is sufficient for this. Thereafter, the liquid flows through the passage 14 in accordance with arrows 21, 22 and 24 to the groove 27, where the liquid is divided as indicated by arrows 38 and 39. The liquid flowing in accordance with arrow 38 enters the first part 31a of by-pass channel 31, adjusting the desired flow rate by positioning groove 34 and then flowing to outlet channel 30 as indicated by arrows 40. The fluid deflected in accordance with arrow 39 exerts a pressure on membrane 7, thereby moving it toward the rim 31. As a result, the pressure drop across the partially closed mouth of the duct 30 is controlled and the pressure drop across the control arrangement 29 is kept constant so that the flow of fluid remains constant. If the appliance is sterilized before use, the appliance parts through which the liquid flows or is present remain sterile as the appliance remains completely sealed.

25 As will be apparent, the apparatus of the invention is fully automatic. If the fluid pressure in the container becomes too low, the diaphragm 6 will abut the edge 15 and the liquid supply will be interrupted. The fluid flow rate is set by the control arrangement and automatically held constant by the diaphragm 30 7.

Several containers containing liquid to be administered may be connected to the apparatus. When the containers contain the same fluid, administration to the patient can be carried out for a long period of time without interruption. When the containers are filled with various liquids to be administered to the patient as a mixture,

DK 153593B

take this manually by adjusting the pins 19 or, for example, by means of a device which operates in accordance with a fixed system which can be controlled remotely. The latter option can be performed automatically in a simple manner after a 05 fixed program.

10 15 20 25 30 35

Claims (7)

1, Apparatus for controlling fluid flow, especially by intravenous administration of fluid and containing a supply chamber (10) with an inlet channel (8), a filter chamber (11) 05 connected to the supply chamber (10) through a passage (14) and an outlet chamber (17 ) connected to the filter chamber (11), characterized in that a first diaphragm (6) is disposed in the storage chamber (10) to cover the passage (14) between the storage chamber (10) and the filter chamber (11), the AT 10 inlet channel (8) under tension. ) opens in the storage chamber (10) on the same side of said first diaphragm (6) as the passage (14), A second diaphragm (7) in the outlet chamber (17) divides this into two separate parts (17a, 17b) which are connected through an by-pass channel (31a, 31b), and the AT apparatus further includes control means (29) for adjusting the by-pass channel (31a, 31b) flow area and an outlet channel (30) connected to that portion of the outlet chamber (31). 17b), located downstream of the by-pass channel (31a, 31b), wherein the second diaphragm (7) is movable in the direction towards and away from the outlet duct (30) for variation of its flow area in accordance with the pressure difference between the two outlet chamber portions (17a, 17b). Apparatus according to claim 1, characterized in that an opening (18) aligned with an outlet end (9) for the inlet duct (8) is arranged in a wall (2) in the storage chamber (10) lying on the opposite side of said first diaphragm (6) relative to the inlet duct (8), and AT an element (19) may be inserted into the opening (18) to press said first diaphragm (6) against and thereby close the inlet duct (8) outlet end (9). Apparatus according to claim 2, characterized in that several inlet ducts (8) are connected to the storage chamber (10) and that a corresponding number of openings (18) are arranged in the opposite wall (2) of the storage chamber (10) aligned with the outlet ends (9) of the respective inlet ducts (8). Apparatus according to claim 1, 2 or 3, characterized in that a wall (2) in the storage chamber (10) on the opposite side of the DK 153S93B membrane (6) in relation to the passage (14) between the storage chamber (10) and the filter chamber (11) has an opening (20) aligned with the passage (14) into which opening (20) can be inserted to push said first membrane 05 (6) into and thereby close the passage (14). Apparatus according to claim 1, characterized in that the control devices (29) contain a cylindrical body (33) which is rotatable about its axis and which has a groove (34) extending around a part of the body (33). perimeter, the bottom of this 10 groove extending along a circular arc eccentric to the axis of the body (33), and the depth of the groove (34) increasing from 0 mm at one end to 0.5 mm at the other end of the groove (34). Apparatus according to claim 5, characterized in that the groove 15 (34) is V-shaped in cross-section. Apparatus according to claim 5 or 6, characterized in that the cylindrical body at the end of the groove (34), where this is deepest, is provided with a further groove (37) having a flow area at least equal to by-pass 20 the flow area of the channel (31a, 31b). 25 30 35