FR2476490A1 - INFUSION APPARATUS AND METHOD FOR CONTROLLING THE SAME - Google Patents

Abstract

INFUSION DEVICE INCLUDING A PUMP-CASSETTE COMBINATION FOR SENDING FLUID OR SEMI-SOLID FROM AN UPPER SECTION TO A DOWNSTREAM SECTION OF THE UNIT. THE CASSETTE 18 INCLUDES A RIGID BOX 34 DEFINING A PUMPING CHAMBER 25 WITH AN OPEN SIDE IS COVERED BY A DIAPHRAGM, ON WHICH AN OPERATING BODY 28 ACTS TO VARY THE VOLUME OF THE CHAMBER 25. CONES 21, 22 OPEN AND CLOSE. DUCTS 11 AND 13 SERVING CHAMBER 25 IN A SEQUENCE LINKED TO THE MOVEMENT OF ORGAN 28 SO THAT CHAMBER 25 IS ALTERNATIVELY FILLED AND QUASI EMPTY. TO MINIMIZE THE BORING EFFECTS OF THE AIR PRESENT IN CHAMBER 25, THE ORGAN 28 IS CONTROLLED IN A MANNER TO: 1 SENSITIVELY INCREASE THE VOLUME OF CHAMBER 25 BEFORE OPENING UPSTREAM DUCT 11; AND RETURN THE VOLUME OF CHAMBER 25 TO LESS THAN 0.07ML AFTER CLOSING DUCT 11 AND OPENING DUCT 13.

Description

The present invention relates to apparatus for

  merger and concerns in particular such a device and its mode

control.

  The US patent discloses an infusion apparatus for pumping a fluid or semi-solid product from an upstream section to a downstream section. The pump has upstream and downstream pipe sections and a removable cassette establishing communication between these

  two sections. The cassette has a window and a diaphragm

  placed me across this window. Means carried by the pump acting on the diaphragm to vary the volume of the pumping chamber defined by the cassette. The cassette has inlet and outlet ports communicating, without valve interposition, with said chamber. Pumping

  of fluid in the driving sections is operated by

  these sections at upstream and downstream locations and appropriate movement of the contents of the

  cavity or pumping chamber of the cassette.

  The infusion apparatus described in this application offers significant advantages over many prior art structures. The absence of valves in the cassette significantly improves reliability and thus reduces the

  complexity of manufacture and therefore the cost price. The con-

  the cassette also ensures better accuracy.

  than those according to the prior art. By adequate control of the pinching suffered by the tubes at the inlet and the outlet of the cassette, the flow rates are made very constant,

  even when they are very weak.

  However, it has been observed that in the perfusion apparatus

  As described above, the presence of air in the pumping chamber of the cassette may adversely affect the operation of the apparatus. These unfortunate effects result

  of three phenomena. First, with strong counter

  pressures, the fluid level rises, in the chamber of

  drip that feeds the device, due to a dilatation

  air pressure when the inlet valve opens before filling. This upward flow of

  fluid into the drip chamber can trigger

  unnecessarily warning devices, such as

  user of bottle exhaustion. Secondly, the flow rate decreases as the back pressure and the air volume increase, which affects its accuracy. Third, in the presence of low or negative backpressures (appearing for example when the needle is at a significant distance of -30 to -90 cm, below the cassette), the flow

  delivered increases because the air expands when

  exit valve, which also affects the pre-

  decision. The effects of the air present in the cassette can be substantially reduced or eliminated by giving the outlet of the pumping chamber a location such that the air bubbles progress towards this outlet and are forced out with

  the fluid or semi-solid expelled. Such a principle is

  in the cassette described in US Patent 4,140,118,

  February 1979. Although satisfactory, such an agreement

  may cause confusion on occasion

  hospital staff seeking to identify the entrance. This-

  teambuilding stems from the fact that most

  Existing melting or drip currents are designed so that the flow takes place continuously downwards. In addition, the cassette according to US Patent 4,140,118 contains small inlet and outlet valves and is therefore expensive for application where the cassette is discarded after a single use or after 24 hours, for reasons of sterility. The present invention aims to propose

  - a combination of pump and cassette for drop-in

  drop, and a method for its control; - more particularly, a drip comprising the combination of pump and cassette, remarkable in that the effect exerted on the accuracy by the air present in the cassette is substantially eliminated and in that the cassette

  is easy to install in the pump and does not raise any ambiguity

  tee for putting drip into working order; a method for controlling a drip which minimizes the effect on accuracy by the presence of

air in the pumping chamber.

  Other objects of the invention will appear to the man of

  art from the description that we will now give in

  Referring to the accompanying drawing, in which: Figure 1 is a schematic view of a drip made according to the present invention; Figure 2 is an exploded cross-sectional view of a cassette for the drip according to Figure 1;

  Figures 3 and 4 are schematic cross-sectional views

  ticks illustrating the operation of the pump according to Figure 1; and Fig. 5 is a diagram illustrating the operation

  the cam motor means shown in FIG.

  In a very general way, the infusion apparatus or

  drip according to the invention (FIG. 1) moves by pumping

  page a fluid or semi-solid of a section of flexible duct

  upstream 11 up to a downstream flexible duct section

  13. The upstream duct section 11 may be in communication with

  with a source 12 of fluid, and the downstream flexible conduit section 13 can be secured to appropriately administer the fluid or semi-solid to a patient 14. The apparatus comprises a pump 15 which includes see Figure 3) means 16 and 17 for supporting the duct sections 11 and 13 respectively. First throttling means 21 are provided for throttling and selectively opening the upstream duct section 11. Second throttling means 22 are provided for throttling and selectively opening the downstream duct portion 13. A replaceable cassette of the

  means 23 and 24 to be connected respectively to the con-

  upstream and downstream duct 13. The cassette 18 defines a chamber

  Pumping device 25 partially delimited by a flexible diaphragm 26. Means 27 removably support the cassette in position interposed between the upstream and downstream pipe sections for connection thereto. Operating means 28 act on the membrane 26, and are movable between a full retraction position (Figure 3) and a full extension position (Figure 4) to move a predetermined volume in the pumping chamber. Means 29 act on the operating means and on the first and second throttling means in a sequence such that fluid or semi-solid is discharged from the upstream conduit section into the downstream conduit section. In order to minimize the unpleasant effects of the air present in the chamber of Dortpage 1) the operating means are controlled so as to increase

  the volume of the pumping chamber before the opening

  ture of the upstream section to fill the cavity;

  and 2) the maneuvering means are controlled in such a way as to

  the volume of the pumping chamber to a residual value

  less than 0.07 ml, once the upstream section closed and the downstream section open to expel the contents of the chamber. Therefore, the maximum volume of air that can remain in the cassette is about 0.17 ml since the inlet and outlet channels may also contain about 0.10 ml of air. This small amount of air (0.17 ml) exerts only a negligible effect on the precision

flow.

  We will now consider in particular Figure 1, which shows the apparatus according to the invention in the form of a

  intervein drip for administration to a patient

  holds 14 fluid from a reservoir or means of storage.

  12. The fluid is introduced intra-

  vein through a suitable catheter 30, attached to the

  downstream 13 of the drip. Adhesive tape 31

  holds the catheter in place on the patient's arm 14, a

  a manner well known to those skilled in the art. The fluid reservoir

  of 12 can be a common bottle for intravenous drip, hanging from a support 32. A chamber of

  droplet 33, attached to the lower part of the

  teille 12, may be of traditional structure. A warning

  bottle depletion unit, not shown, of suitable structure, can be placed above the chamber 33 or fixed thereto to signal the exhaustion of the contents of the

  bottle 12. The contents of the bottle 12 pass through the

  upstream duct 11 constituted by the drip,

  in the illustrated example, by a flexible hose.

  Although, as shown, the bottle 12 is placed on the support 32 at a high level with respect to

  patient 14, as is the case for many drop-in

  intravenous drop, it is not essential with the

  according to the invention to place the bottle as high, since the fluid reaches the patient under the effect of positive pumping of the pump 15. The pump 15, shown in Figure 1, is advantageously contained in an envelope 34 provided with control buttons such as 35. The pump 15 may rest on a bedside table 39 or other suitable structure and is interposed between the upstream 11 and downstream 13 sections of the drip. Washers 41 seal upstream sections 11 and downstream 13 at the inlet and the outlet

of the envelope 34, respectively.

  The apparatus according to the invention comprises, in the pump 15,

  replaceable cassette 18. The cassette used in the

  The device according to the invention requires no valve, which greatly simplifies the apparatus and greatly reduces the cost of its replaceable section. In addition, the apparatus according to the invention comprises a cassette in which a significant volume is displaced at each pumping stroke. This displaced volume is preferably

  in the apparatus according to the invention, of at least 0.25 ml.

  The cassette is shown in isolation in FIG.

  Essentially, this cassette has only three parts.

  The main piece is a molded casing 43 made of plastic material

  tick of appropriate medical quality. The periphery of the housing is preferably generally circular in shape yet drawing corners, but which are rounded. It is planned a

  endpiece 23 to be connected to the upstream duct section of the appliance.

  infusion line, and (on the opposite side of the housing 43) an

  end 24 to be connected to the downstream conduit section of this device.

  mera. Unlike many cassettes according to

  the tips do not contain valves.

  The housing 43 defines the pumping chamber 25, which is

  general cylinder shape having an open side. An obvious

  Annular element 45 surrounds the open side of the pumping chamber and receives the annular lip 47 of a diaphgram or flexible membrane 26. This diaphragm 26 is made of a material

  suitable medical grade hose, impermeable to

  or semi-solid to pump and able to flex as de-

  written below to a sufficient extent to enable

  move the desired volume, as also described in detail below.

  below. To keep the flexible diaphragm in place, a

  mounting ring 49 fits together in a recess

  annular rim 51 protruding on the housing 43 and is hermetically

  mounted on the housing, for example by welding

  to form a seal and hold the diaphragm 26 in place across the open side of the pumping chamber 25. As previously indicated, throttling means 21 and 22 are provided for throttling and sequentially opening the conduit sections. upstream 11 and downstream 13 respectively, in a sequence such as to ensure in the manner of valves the fluid pumping of the upstream duct section 11 in the downstream duct section 13 of the drip. Although any means suitable for throttling the duct sections can be adopted as will be described below, in the apparatus shown by way of example in FIGS. 3 and 4, the throttling means 21 and 22 are the ends

  tapered bars, 63 and 65 respectively. These bars

  res are supported, by suitable means not shown, so as to be movable inside the envelope or

  body 34 of the pump 15. The rounded tops of their ends

  tapered mates 21 and 22 are

  respectively upstream 11 and downstream 13. These sections

  ducts are supported in complementary grooves

  in a frame 16 inside the body 34 of the pump 15. A frame 53 extends across the frame 16, as shown, to form a seal between the region of the

  cassette 18 and the engine means described below.

  The operating means 28 are constituted by the end

  rounded mity of an oblong bar 67 movable in a suitable support, not shown, mounted on the frame 16. The maneuvering means constituted by the rounded end of the

  bar 67 bear diaphragm 26 on the whole side where-

  green of the pumping chamber 25 of the cassette 18. When the cassette is correctly mounted, the operating means 28 slightly extend the diaphragm 26 inward, even at the end of retraction stroke, thus remaining constantly

  in contact with the diaphragm during the entire pumping race.

  page. The volume of the pumping chamber has, in this position of maximum retraction of the bar 6-7, its maximum operating value. As bar 67 moves inward, it extends the membrane inward as shown in FIG. 4, which reduces the volume of the

pumping chamber 25.

  The pump 15 has an articulated door 27, which opens to allow the installation and removal of the cassette 18 and the

  sections of the upstream 11 and downstream sections 13 located in the

  34. As can be seen from the figures

  3 and 4, when the door 27 is closed, a spring with

  din 55, held in a recess 57 formed in the door and covered by a plate 59, presses a pressing cup 61 against the cassette casing 43, thus maintaining this housing

  in place against the chassis 16. Prescribed blocks are

  62 and 64, respectively fixed to the door by screws

  66 and 68. The block 62 is placed on the side of the

  upstream duct 11 opposite the bar 21. Similarly, the block 64 is placed on the side of the downstream duct section

  13 opposite to the bar 22. By judiciously adjusting the posi-

  of the blocks 62 and 64 with the aid of the screws 66 and 68, the pressure exerted in service can be adjusted during manufacture.

  by the throttling means 21 and 22 to ensure the closing

  completely watertight and therefore total

duit as described.

  To ensure the desired sequence of movement of

  throttling means 21 and 22, as well as means for

  -28, the ends of the movable bars 63, 65 and 67 si-

  the opposite end of the cassette and the duct sections carry appropriate cam followers 71 pressed (by springs not shown) against the cam surfaces 91, 93

  and 95. These cams 91, 93 and 95 are mounted on a tree with

  my 97 which turns under the action of a drive motor 103.

  This motor 103 is a stepper motor for rotating by

  increments the tree and thus incrementally ensure the displacement

  cement and the control of the movable bars.

  In FIG. 3, the second throttling means, inferred

  22 is in the desired position to throttle or intercept

  by pinching the downstream flexible duct section 13.

  Due to the suction (depression) caused by the retraction

  of the member 28, as set forth below, the pumping chamber 25 of the cassette 18 fills. The pumping stroke is illustrated in FIG. 4, in which the second throttling means 22 are retracted to fully open the conduit section 13 and the first throttling means 21 are extended to throttle or intercept the conduit section. upstream 11. By moving inward, the operating means 28 reduce the volume of the chamber of

  pumping 25, causing the expulsion of an invariable

  or prefixed content to the downstream section of the drop-to-

  drop. The distance traveled inwards by the maneuvering means 2 determines the volume displaced during the pumping stroke. Filling and pumping races take place

  in sequence and repeat in accordance with the rotation of the

  cam 97 and the configuration of the cams 91, 93 and 95.

  FIG. 5 is a diagram illustrating the movements described, as a function of the degrees of rotation of the shaft, by each of the three sliding bars 63, 65 and 67. In the extreme left position of 00, indicated on the diagram, the bar 63 is in the closed position while the bars 65 and 67 are in the open positions. By moving from the full open position to the occlusion position, the bar 67 moves a predetermined predetermined amount of the contents of the pumping chamber 25. After this movement, the bar 65 takes the occlusion position to intercept the section of the pumping chamber.

  downstream duct 13. After this occlusion, the bar 67 is de-

  place to the open position. Thanks to the elasticity of the diaphragm, the pump chamber expands. The bar 63 starts its movement towards the open position once the bar 67 has described about 20% of its total retraction stroke, which ensures a new filling of the pumping chamber. At about 2700, the upstream movable bar 63 moves from the open position to the closing edge and then the downstream movable bar 65 assumes the open position. The

  device is thus ready to begin the race of

  next step, starting at 0. Since bar 67 retracts plunger 28 to substantially increase the volume of the pumping chamber prior to opening the upstream section, backflow to the drip chamber is prohibited. By increasing "substantially", we intend to increase

  sufficient to absorb the maximum dilatation

  Predictable air in the room. An increase

  approximately 20% of the volume of the chamber of

  before the opening of the downstream section proves to be typical

satisfactory.

  For typical applications of the invention, the maximum effective pressures are about 172 kPa. So we choose

  consequently the "rigidity" of the cassette 18. It is preferable

  that the means of maneuver are against the diaphragm

  during their entire race and that the diaphragm

  days a slight push inward. For accuracy to be satisfactory, it is preferable that the area be

  unsupported diaphragm does not exceed 75% of the total area

the diaphragm (of window).

  With the motor cams represented by way of example, it will be possible to substitute, for manipulating the throttling means, other motor means, such as vismothers. However,

  Incremental control of the diaphragm movement is important.

  aunt to obtain an adequate precision and order. A judicious design makes it possible to choose for each operation the desired displaced volume. An order

  digital is then easily possible with microplates

  commercially available microcomputer jackets and

  relatively inexpensive. Functions such as monitoring

  launches debit, total delivered volume and errors on the

  flow can be easily established by

naked numerical computation.

  It is usually preferable to design the apparatus to operate in such a way that the return strokes of bars 63, 65 and 67 have the same duration regardless of the flow rate and volume of fluid administered. Thus, the flow

  may be more regular if the maneuvering means

  at a relatively high fixed speed while their extension speed (discharge) is variable. Thanks to the possibilities available in the digital domain, such

  operation is easy to obtain.

  The ratio between the size of the outlets and

  input and the diaphragm is important. With original

  fices of entry and exit too large, the inflow

  comes asser important to badly affect the accuracy.

  It is therefore preferable to establish between the cross section of the inlet and outlet ports and the diaphragm area

  or window a ratio not exceeding about 0.3.

  As is the case for any cassette pump, the pre-

  air in the cassette may affect the accuracy of the

  pumping rate. To avoid such difficulties, the

  the invention according to the invention has in combination two characteristics

  which, together, significantly improve the pre-

  decision. Firstly, the member 67 partially retracts (approximately 20%) before the upstream section is opened by retraction of the member 63. This prevents the air in progress.

  in the pumping chamber does not raise the

  veal of fluid in the drip chamber. In the second place, the residual volume that the pumping chamber exhibits when the member 67 is in full extension is chosen (by judicious choice of the stroke length and the geometry of the pumping chamber) of less than about 0.07 ml. and, better, 0.05 ml. To this volume is added that of the sections of

  duct from the cassette to pinch regions, typically

  only 0.1 ml, which gives a maximum volume of occluded air of 0.17 ml. At this level, the effect of air on flow accuracy remains tolerable. Any air present in the cassette in an amount exceeding the residual volume plus the volume of the aforementioned duct sections is expelled from the cassette and can be detected by means

appropriate if it is excessive.

  In addition to those stated above, the drip according to

  the invention offers other advantages over many

  its previous structures. Choosing good excites the

  configuration of the cams and the dimensions of the elements

  strangely mobile, one can obtain very constant flows,

  even up to very low values. For example, the drop

  droplet according to the invention can provide the infusion to a

  flow of one milliliter per hour at the rate of one increment of

  every 26 seconds and with a time to refill

wise of a second only.

  In general, the provisions described are amenable to various modifications without departing, for all that, from the

of the invention.

he

Claims (6)

CLASS I CAT IONS   An infusion apparatus for pumping fluids or semi-solids from a section of flexible upstream duct of the apparatus to a section of flexible duct downstream thereof, characterized in that it comprises a pump (15) comprising means (16, 17) for supporting said sections   the first strangulation means (21) for foreign   selectively open and open said duct section   upstream (11), second throttling means (22) for   selectively opening and opening said downstream pipe section, a cassette (18) having means (23,24) for connecting with said upstream pipe sections (11)   and downstream (13), this cassette defines a pump chamber   pe (25) and having a diaphragm or flexible membrane (26) which defines a portion of said pump chamber (25), means (27) provided on said pump for sustainably   removable said cassette in position interposed between the   the upstream (11) and downstream (13) duct sections, operating means (28) bearing against said membrane (26) and being movable to move between a full retraction position and a full position extension, a predetermined volume in said pumping chamber (25), this   predetermined volume being such that it remains in said chamber   a residual volume of less than 0,07 ml   ron, and means (29) for manipulating said first and second throttling means (21,22) and said operating means (28) in a desired sequence for pumping fluids or semi-solids from said conduit section; upstream (11) in said downstream conduit section (13), which sequence is such that said operating means moves to the full retraction position to increase the volume of the pumping chamber (25) substantially before said upstream duct (11) is not opened by said   first throttling means (21).   2. Infusion apparatus according to claim 1,   characterized in that said predetermined volume is at least About 0.25 ml.   3. Infusion apparatus according to claim 1,   characterized in that said connecting means and said duct sections define, between said pumping chamber (25) and said restricting means (21,23), a volume contiguous to said pumping chamber, and that the sum of this contiguous volume and said residual volume of the pumping chamber is less than about 0.17 ml. 4. Method of controlling an infusion apparatus for   pumping fluids or semi-solids from a cross-section of   flexible duct (11) of the apparatus at a downstream flexible duct section thereof, characterized in that   it comprises a pump (15) comprising means for supporting   said conduit sections (11, 13), first throttling means (21) for selectively throttling and opening said upstream conduit section (11), second means for   throttling (22) to throttle and open selectively the-   said downstream duct section (13), a cassette (18) com--   carrying connecting means (23, 24) to said sections   upstream (11) and downstream (13) duct, said defined cassette   a pumping chamber (25) and having a diaphragm   me or flexible membrane (26) which defines a portion of said pumping chamber (25), means (27) provided on said pump (15) for removably supporting said cassette   (18) in a position interposed between said sections of   upstream (11) and downstream (13), operating means (28) bearing against said membrane (26) and movable to move, between a full-retraction position and a fully extended position, a volume predetermined in said pumping chamber (25), and means (29) for manipulating said first and second throttling means (21,22) and said operating means (28) in a desired sequence for pumping fluids or semi- solids of said upstream duct section (11) in said downstream duct section (13), said predetermined volume being such that there remains in said pumping chamber (25) a residual volume of less than 0.07 ml, said sequence being such that said means of   (28) move to the full position   pulling to substantially increase the volume of the pumping chamber (25) prior to opening said conduit section   upstream (11) for movement of said first means of (21).   5. Infusion apparatus according to claim 4,   characterized in that said predetermined volume is at least About 0.25 ml.   6. Infusion apparatus according to claim 4,   characterized in that said connecting means (23,24)   and the sections of said duct sections interposed between   being said pumping chamber (25) and said foreign means   (21,22) define a volume contiguous to the said room   pumping, and that the sum of this contiguous volume   and said residual volume of the pumping chamber is less than less than 0.17 ml