CA1136507A - Apparatus for controlling the flow of intravenous fluid to a patient - Google Patents

Abstract

APPARATUS FOR CONTROLLING THE FLOW OF
INTRAVENOUS FLUID TO A PATIENT

Abstract of the Disclosure Apparatus is included in a system for controlling the flow of intravenous fluid from a source to a patient.
Such apparatus is manually adjustable to vary the rate of such fluid flow. Desired rates of fluid flow may also be set in such system when the apparatus is included in the system.
The system then overrides any previous manual adjustment of such apparatus and adjusts the rate of fluid flow in accordance with any such setting. When a desired rate of fluid flow has been preset into the system, the system then operates to adjust the rate of fluid flow on an instantaneous basis so that the desired rate of fluid flow is maintained.
The apparatus is removably disposed in the system for controlling the flow of fluid to the patient. Even after the adjustment by the system of the rate of fluid flow in accordance with any setting, the apparatus may be removed from the system to provide a rate of fluid flow in accordance with the manual adjustment of the apparatus.
A plug member in the apparatus defines a passage communicating at a first position with an inlet line and, at a displaced position in a particular direction, with an outlet line. A resilient member such as a diaphragm may be disposed in the particular direction in the passage and may be displaced in a transverse direction from the inlet and outlet lines. A rod stretches the diaphragm in the transverse direction. A button may envelope one of the inlet and outlet lines to cooperate with the diaphragm in limiting the rate of flow of fluid through the passage. The button may have a notch cooperating with the diaphragm in facilitating the flow of fluid through the passage at the desired rate. A
knob may be adjustably threaded on the plug member to press the rod against the diaphragm with a force dependent upon the adjustments of the knob.
* * *

Description

` 113~5~7 1 This invention relates to removable apparatus for

2 controlling the flow of intravenous fluid from a source to

3 a patient. The invention particularly relates to apparatus

4 for providing for precise controls over the rate of fluid flow to a patient during the operation of the apparatus under normal 6 circumstances such as in the room assigned to the patient and 7 for controls over the rate of fluid flow in accordance with manual 8 adjustments during such abnormal conditions as the transport 9 of a patient from one room to another. More particularly, the invention relates to apparatus for providing for a manual control 11 over the rate of fluid flow to a patien~ when removed from a 12 system, for a setting of rate in a system upon insertion of the 13 apparatus into the system and an overriding of the manual control 1~ by the system setting under such circumstances and for the reassertion of the manual control upon a removal of such apparcl~us 16 from the system.

18 As the practice of medicine becomes increasingly 19 complex and increasingly refined, the equipment and techniques used to provide care for a patient have become increasingly 21 sensitive in order to assure that the patient receives optimum 22 care. For example, after an operation has been performed on 23 a patient and the patient is in the recuperative state, intravenous 2~ fluid often has to be introduced to the patient. The rate of introduction of fluid to the patient is dependent UpOIl a number 26 of different fac~ors including the weight, age, sex and physical 27 state of the patient. As the patient recovers from his illness, 28 the rate of introduc-tion of the intravenous fluid to the patient 29 is preferably adjusted to assure that the patient receives an optimum benefit from the fluid.

113~5Q7 A considerable effort has been devoted over a substantial period of time to provide a satisfactory system for controlling the rate at which fluid such as intravenous fluid is introduced to a patient. Considerable progress has been made in developing a sat-isfactory system for certain types of operations. For example, a system providing for the pumping of fluid on a precise volumetric basis to a patient has been disclosed and claimed in Canadian patents 1,060,302 and 1,078,692, and assigned to the assignee of record of this application.
A number of fundamental problems have remained until fairly recently in systems providing for the flow of fluid on a gravitational basis to a patient. Such problems have existed until recently even though a considerable effort has been devoted to the solution of such problems. For example, a satisfactory system has not existed until recently for providing for the intro-duction of fluid to a patient on a gravitational basis at a precise and predetermined rate. Furthermore, a system has not existed un-til recently which could be used on a sterile and hygienic basis for different patients such that any contamination from the use of the system for one patient would not affect the health or safety of subsequent patients.
Patents have been recently obtained which disclose and claim systems for overcoming the above difficulties. For example, United States Patent no. 4,207,871 issued on June 17, 1980 assigned to the assignee of record of this application discloses and claims a system for providing for the flow of intravenous fluid to patient on a gravitational basis at a precise and predetermined rate and for providing a sterile and hygienic operation for individual -113~iS~7 patients.
Canadian application serial no. 328,354 has also been filed by me on May 25, 1979, for a "Cassette for Intravenous Controlier" and has been assigned by me to the assignee of record of this application. This application discloses and claims a cassette which is disposed in the system to provide for the flow of fluid on the controlled basis to the patient and which is easily removable from the system so that a sterile cassette can be replaced in the system for a previously used cassette every time that the system is to be used for a different patient.

Although the system and cassette disclosed and claimed in the patent and application specified in the previous para-graphs provide for the flow of fluid on a gravitational basis to a patient at precise rates under sterile conditions, improvements would be still desirable to enhance the scope of operation of the system. For example, it would be desirable to provide a system which could be coupled to a patient even during movement of the patient and which would provide for a flow of fluid to the patient at controlled rates during such movement. In this way, intravenous fluid could be introduced to the patient at such controlled rates even during the movement of the patient from an operating room to a recovery room or from the recovery room to a room of permanent assignment in a hospital. It would also be desirable to provide such a system with instantaneous capabilities of controlling pre-cisely and automatically the flow of fluid on a gravitational basis to the patient after the movement of the patient to a room of 113~S07 l permanent assignment. As will be seen, a system of such 2 capabilities would have a considerable flexibility in operation 3 since it would provide for a controlled flow of fluid to a 4 patient under all conditions which may be encountered in a hospital.

7 This application provides a system with the 8 capabilities discussed in the previous paragraph. The system 9 includes apparatus which is free-standing and which is manually adjustable at such times to vary the rate at which intravenous ll fluid flows to a patient. Such manual adjustments may be 12 operative to control the rate of fluid flow during the time 13 that a patient is being moved from an operating room to a 14 recovery room or from the recovery room to his assigned room.

16 The apparatus may also be inserted easily and 17 conveniently into a system when the patient is recuperating in 18 his assigned room. At such times, desired rates of fluid flow l9 may be set in such system, which then overrides any previous manual adjustment of such apparatus and adjusts the rate of 21 fluid flow in accordance with any such setting. This provides 22 for a precise control of the flow of fluid in accordance with 23 such settings during the time that the patient is in his 24 assigned room.

26 In this way, the precise controls can })ec.~me 2~ operative when the patient has been moved to his assigned room 2~ and the system is operative on a semipermanent basis in the 29 assigned room. When a desired rate of fluid flow has been preset into the system, the system then operates in a servo ~2 1136S~7 1 loop to adjust the rate of fluid flow on an instantaneous 2 basis so that the desired rate of fluid flow is precisely 3 maintained.

The apparatus is removably disposed in the system 6 for controlling the flow of fluid to the patient. As a 7 result, the manual adjustment may be provided when the 8 apparatus is removed from the system and the system control 9 of the rate of fluid flow may be provided when the apparatus has been coupled into the system. The removal of the 11 apparatus from the system or the coupling of the apparatus 12 into the system may be provided easily on an instantaneous 13 basis.

The apparatus includes a plug member defining a 16 passage which communicates at a first position with an input 17 line and, at a displaced position in a particular direction, 18 with an output line. A resilient member such as a diaphragm 19 may be disposed in the particular direction in the passage and may be displaced in a transverse direction from the input 21 and output lines. A rod may extend into the passage to 22 stretch the diaphragm in the transverse direction. A button 23 may envelop one of the input and output lines to cooperate 2g with the diaphragm in limiting the rate of flow of fluid through the passage in accordance with the stretching of the 26 diaphragm in the transverse direction. The button may have 27 a notch cooperating with the diaphragm in facilitating the 28 flow of fluid through the passage at the desired rate.
29 knob may be adjustably threaded on the plug me~er to press the rod against the diaphragm.

` 1136S(~7 The knob may be manually adjusted, during the movement of the patient from the operating room to the recovery room or from the recovery room to his assigned room, to control the rate at which fluid flows to the patient. The knob may be coupled to a driving member when the apparatus is inserted into the system.
At such times, a motor drives the driving member through an angle dependent upon a rate which is preset into the system. In this way, the diaphragm is stretched in the transverse direction in accordance with the operation of the motor. The motor may be servo-controlled to adjust the stretching of the diaphragm at each instant in the transverse direction in accordance with the rate at which drops of the fluid are actually flowing to the patient. This servo-control insures that the actual rate of flow of fluid to the patient corresponds to the rate preset into the system when the apparatus is inserted into the system.
The apparatus included in this invention is adapted to be used in the system disclosed and claimed in United States Patent No. 4,207,871 issued June 17, 1980. It is also adapted to be in-cluded in the cassette disclosed and claimed in Canadian Patent application number 328,354 filed May 25, 1979 or to be used as a separate item in the system without including the cassette in the system.
IN THE DRAWINGS:
Figure 1 is a schematic diagram, partly in block form, of a system for controlling the flow of intravenous fluid to a patient o~ a gravitational basis;

~ ,, 113~iSC)q 1 Figure 2 is a sectional view of control apparatus 2 capable of being included in the system of Figure 1 and shows 3 the positioning relative to such control apparatus of a drop 4 sensor included in the system shown in Figure l;

6 Figure 3 is a sectional view of the apparatus shown 7 in Fiyure 2 when the apparatus is removed from the system shown 8 in Figure 1 and is in a position to provide for the flow of 9 fluid at a very low rate;

11 Figure 4 is an enlarged fragmentary sectional view 12 of certain elements of the apparatus shown in Figures 2 and 3;

14 Figure 5 is an exploded perspective view of the system shown in Figure 1 and of the apparatus of Figures 2 and 3 in 16 a position removed from the system; and 18 Figure 6 is a schematic view of a cassette which may 19 be constructed to include the apparatus of Figures 2 and 3.
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21 Figure 3 illustrates equipment which forms a part of 22 this invention and which provides for flow of intravenous 23 fluid to a patient at a rate dependent upon a manual adjustment 24 of such apparatus. The equipment includes a source 10 of intravenous fluid and a conduit 12 extending from such source 26 to apparatus generally indicated at 14 and forming d part of 27 this invention. An output conduit 16 extends from the 2~ apparatus 14 to a patient schematically illustrated at 20.
2g The apparatus 14 includes a plug member 22 formed 31 from a suitable material such as a plastic material. The 113~i507 1 plug member 22 is provided with an input line 24 constructed 2 to receive the input conduit 12 and with an output line 26 3 constructed to receive the output conduit 16. A cavity or 4 passage 28 is disposed between, and in communication with, the input line 24 and the output line 26. Button 30 is 6 disposed in the passage 28 in a closed loop around one of 7 the lines such as the output line 26 and is preferably 8 provided with an annular configuration. The button 30 is 9 preferably notched at one position as at 31 (Figure 4) to 0 facilitate the flow of fluid on a controlled basis. The 11 notch 31 may be V-shaped to provide a progressive control 12 over the rate of fluid flow.

14 A resilient member such as a diaphragm 32 is disposed in the cavity or passage 28. The ends of the 16 diaphragm 32 are provided with a bulbous construction and 17 the bulbous ends are disposed in sockets 34 in the plug 18 member 22 to maintain the diaphragm in a taut relationship.
19 The diaphragm 32 is disposed so that it extends in the same direction as the dlstance between the input line 24 and 21 the output line 26 at the positions at which these lines 22 communicate with the passage 22.

24 A pusher rod 36 is disposed in a socket 38 in the plug member 22. The pusher rod 36 is disposed against the 26 diaphragm 32 at a position intermediate the sockets 34 to 27 stretch the diaphragm iIl a direction transverse to the 28 disposition of the diaphragm in the passage 22. A knob 40 29 is internally threaded on a threaded protuberance 42 extending from the plug member 22. The knob 40 presses against the 1~36S~7 1 pusher rod 36. The knob 40 may be provided with a frusto-2 conical external surface which may be knurled or otherwise 3 deformed to facilitate gripping.

The knob 40 may be rotatably adjusted on the 6 protuberance 42 to adjust the pressure exerted against the 7 pusher rod 36. This in turn provides for an adjustment of 8 the force exerted by the pusher rod 36 against the diaphragm 9 32. In this way, the position of the diaphragm 32 adjacent 0 the button 30 may be adjusted in accordance with adjustments 1 in the positioning of the knob 40 so as to control the rate 12 at which fluid flows through the passage 28 from the input 13 line 24 to the output line 26. The manual adjustment of the 1~ knob 40 accordingly provides for a control of the rate at which fluid flows from the source 10 to the patient 20.

17 The notch 31 is provided in the button 30 to obtain 18 a flow of fluid to the patient at low rates in acc~rda~ e 19 with the adjustment of the knob 40. This may be seen on a schematic basis in Figure 4. At such low rates, the diaphragm 21 32 tends to be drawn into the notch 31. The positioning of 22 the diaphragm 32 in the notch 31 is dependent upon the 23 adjustment of the knob 40. As a result, for low settings 24 of the knob 40, fluid can flow through the passage to the output line only in the space between the diaphragm 32 and 26 the bottom of the V-shaped notch 31.

2~ The apparatus disclosed above is adapted to be 29 used when the patient is being moved from an operating room to a recovery room or from a recovery room to an assigned 113~5~7 1 room. Since the apparatus 14 is relatively small and can 2 even be held in the palm of a hand, it can be held by a 3 nurse or even can be disposed in the palm of a patient as 4 the patient is being moved from one room to another. During such movement, the rate of flow of fluid to the patient can 6 be controlled by the adjustment of the ~nob 40 on the protu-7 berance 42.

9 Figure 1 illustrates a system for providing an automatic control over the rate of flow of fluid on a 11 gravitational basis to a patient. The system includes the 12 apparatus 14 shown in Figures 2 and 3 and described in detail 13 above. The apparatus 14 is adapted to be supported in fixed 14 position relative to such system by a housing generally indicated at 50 in Figure 5. The holder includes a drive member 52 16 (Figure 5) which is provided with a socket 54. The socket 54 17 is knurled or otherwise deformed in a manner similar to the 18 external surface of the knob 40 so as to engage the knob and 19 rotate the knob as it rotates. The drive member 52 may be spring loaded to facilitate the driving relationship between 21 it and the knob 40. The drive member 52 is adapted to be 22 driven by a stepper motor 56.

24 The stepper motor 56 is included in an electrical system which is shown on a schematic basis in Figure 1. The 26 system includes settings 58 (Figure 5) which are disposed on 27 the front panel of the housing 50 and which are preferably 28 provided with digital capabilities of a plurality of digits 29 of progressive value. For example, three digits may be provided to register the values of units, tens and hundreds -- 113~i5~7 1 to provide capabilities of selecting rates of digital flow 2 between values of "1" and "999".

4 The selections in the settings 58 are introduced to a comparator 60 tPigure 1) which compares such desired values 6 with the actual values of flow provided by a drop sensor 62.
7 The drop sensor may be of a conventional construction and is 8 operative to sense the number of drops of fluid flowing 9 through the output line 12 in a particular period of time such as one second. The comparator 60 compares the signals 11 from the settings 58 and the drop sensor 62 and produces an 12 error signal representing any differences between the 13 characteristics of the signals being sensed. The error 14 signal is then introduced to the stepper motor 56 to operate the stepper motor in a direction for reducing the error 16 signal. The stepper motor drives the drive member 52, which 17 in turn drives the knob 50, in a direction to control the flow 18 of fluid through the passage 28. In this way, the stepper 19 motor 56 is controlled on an instantaneous basis to obtain a flow of fluid through the output line 16 at a rate directly 21 related to the values provided in the settings 58.

23 As will be seen from Figure 5, tlle apparatus 14 24 is adapted to be removably disposed in the housing 50. The housing 50 may include the drive member 52 and the stepper 26 motor 56. In this way, the apparatus 14 may be easily 27 coupled into the housing 50 when the system SilOWIl in Fiyure 5 28 is to be operative in an assigned room of a patient to provide 29 a flow of fluid to the patient at a precise rate in a closed-loop.

113~iS~7 The apparatus 14 may be easily decoupled from the housing 50 to operate independently of the system when the patient is being moved from an operating room to a recovery room or from a recovery room to an assigned room. Under such circumstances, the manual adjustment of the knob 40 is sufficient to regulate the flow of fluid at a desired rate with sufficient accuracy in an open-loop servo so that the patient is receiving good medical attention.
The apparatus 14 may also be included in a cassette which is generally indicated at 70 in Figure 6 and which is dis-closed and claimed in Canadian application No. 328,354 filed May 25, 1979. As disclosed in such application, the cassette 70 may be included in a system, such as that shown in Figure 1, for controlling the rate of flow of intravenous fluid to a patient on a gravitational basis. When the apparatus 14 is included in the cassette 70, it may be permanently disposed in the cassette rather than being removable as in the embodiment described above.
However, even when the apparatus 14 is included in the cassette, it has the flexibility of being manually adjustable to control the rate of flow of intravenous fluid to a patient or of being con-trolled by the system in accordance with adjustments in the setting S8 shown in Figure 5.
When the apparatus 14 is included in the cassette 70, it may be disposed at any convenient position in the hydraulic cir-cuit provided by the cassette. This hydraulic circuit is shown on a schematic basis in Figure 6 for example, the apparatus 14 may be disposed at a position 71 ~3~5(~7 1 designated as "X" in an input line 72 in the cassette. The 2 position "X" is provided in the input line 72 at a position 3 in advance of any branching of the fluid into auxiliary lines 4 in the cassette. In this way, all of the fluid flowing through the cassette passes through the apparatus 14.

7 The hydraulic circuit shown in Figure 6 includes 8 a pair of auxiliary lines 74 and 76 extending from the input g line 70 to opposite ends of a chamber generally indicated at 78. Valves 80 and 82 are respectively disposed in the 11 auxiliary lines 74 and 76. A resilient member such as a 12 diaphragm 84 is disposed in the chamber 78 to divide the 13 chamber into a pair of compartments 86 and 88. Auxiliary 14 lines 90 and 92 respectively extend from the compartments 86 and 88 to an output line 94. Valves 96 and 98 are respectively 16 disposed in the auxiliary lines 90 and 92. The apparatus 14 17 is preferably disposed in the output line 94 as illustrated 18 in Figure 6.

The diaphragm 84 is stretchable in the chamber 78 21 to increase the volume of one of the compartments and 22 correspondingly reduce the volume of the other compartment.
23 A transducer generally indicated at 100 is movable with the 24 movement of the diaphragm to indicate the disposition of the diaphragm at each instant. The transducer 100 produces at 26 each instant a signal which controls the direction in which 27 fluid flows into and out of the chamber. For example, the 28 valves 80 and 98 may be initially open and the valves 82 and 29 96 may be initially closed. In this relationship, fluid flows into the compartment 86 and out of the compar-tment 88 113~50~

1 and accordingly stretches the diaphragm 84 into the compartment 2 88. When the diaphragm has stretched to a particular limit, 3 the transducer 100 produces a signal which causes the valves 4 80 and 98 to close and the valves 82 and 96 to open. In this relationship, fluid flows into the compartment 88 and out 6 of the compartment 86 and accordingly causes the transducer 100 7 to stretch into compartment 86.

g In this way, fluid flows at alternate times into the compartment 86 and out of the compartment 88 and at the 11 other times into the compartment 88 and out of the compartment 12 86. The rate of fluid flow into and outof the con-partments 13 86 and 88 is dependent upon the setting of the knob 40 in 14 the apparatus 14. The setting of the knob 40 may be manually 16 adjusted or the knob 40 may be automatically set by the system 16 of Figures 1 and 5 in accordance with values inserted into 17 the settings 58.

19 The apparatus and system described above has certain importment advantages. It provides for the introduction of 21 fluid on a gravitational basis to a patient at preset rates 22 even when the patient is being moved from an operating room 23 to a recovery room or from a recovery room to an assigned 24 room. This rate of fluid f]ow may be manually preset to any desired value.

27 The apparatus and the system including the apparatus 28 also provide for the flow of intravenous fluid on a gravitational 29 basis to a patient at precisely controlled rates when the patient has been moved to his assigned room. Such precisely 113~5(~7 1 controlled rates may be inserted by a physician or nurse into 2 the system by the operation of the setting 58. The system 3 then operates in a closed-loop servo to insure at each instant 4 that the rate of fluid flow to the patient is precisely regulated at the desired rate inserted by the physician or 6 nurse.

8 The apparatus and system are also advantageous because 9 they can be easily converted between manual control of the rate of fluid flow or system control of the rate of fluid flow.
11 The apparatus and system are further advantageous because 12 the apparatus 14 is relatively small and light and can be 13 easily moved with the patient as the patient is transported 14 from the operating room to the recovery room or from the recovery room to the assigned room.

17 Although this application has been disclosed and 1~ illustrated with reference to particular applications, the 19 principles involved are susceptible of numerous other applications which will be apparent to persons skilled in 21 the art. The invention is, therefore, to be limited only 22 as indicated by the scope of the appended claims.

Claims (37)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. In combination for controlling the rate of flow of fluid to a patient, means for providing for a source of fluid, means defining an inlet line from the source and an outlet line to the patient, means disposed between the inlet line and the outlet line for defining a passage communicating with the inlet and out-let lines, resilient means defining a particular periphery of, and communicating with, the inlet and outlet lines for controlling the size of the passage in accordance with the positioning of the resilient means, and a button disposed in the channel between the inlet line and the outlet line, means adjustably positioned and coupled to the resilient means for varying the positioning of the resilient means in the passage in accordance with such adjustable positioning, to control the rate at which fluid flows through the inlet line to the outlet line, one of the resilient means, the button and the coupling means being provided with a channel to control the rate at which the fluid flows through the passage between the inlet and outlet lines in accordance with the variations in the positioning of the resilient means.

2. The combination set forth in claim 1 wherein the resilient means constitutes a diaphragm defining the particular periphery and the diaphragm is pressed into the passage by the adjustably positioned means to control the size of the passage in accordance with such pressure.

3. The combination set forth in claim 1 wherein the adjustably positioned means are manually adjustable and means are included in the adjustably positioned means for adjustably setting the flow of fluid to any value desired and means are responsive to the adjustable setting of the desired flow of fluid for adjusting the positioning of the ad-justably positioned means in accordance with such setting.

4. The combination set forth in claim 2 wherein the adjustably positioned means constrains the diaphragm into the passage in accordance with the adjustments in the position of the adjustably positioned means and the channel is disposed in the button.

5. The combination set forth in claim 4 wherein the button is provided with a channel in at least one position and wherein the diaphragm is positioned to be constrained into the channel in accordance with the positioning of the adjustably positioned means to facilitate the flow of fluid through the passage and the inlet and outlet lines at the controlled rate.

6. The combination set forth in claim 2 wherein the channel is disposed in the diaphragm.

7. The combination set forth in claim 2 wherein the channel is disposed in the coupling means.

8. In combination for controlling the rate of flow of intravenous fluid to a patient, first means defining an inlet line, second means spaced from the first means and defining an outlet line, the first and second means being spaced by a cavity, and third means disposed in the cavity and defining a sealed passage of adjustable volume for the flow of fluid from the first means into the second means, the first means and the second means being disposed on the same side of the passage defined by the third means, the third means including resilient means disposed in the cavity for controlling the flow of fluid through the passage in accordance with the constraint of the resilient means and further including adjustable means disposed against the resilient means to control the flow of fluid through the passage, a button disposed in the passage to block the flow of fluid through the passage between the inlet and outlet lines, and at least one channel in the button to cooperate with the diaphragm in providing a controlled flow of fluid between the inlet and outlet lines.

9. The combination set forth in claim 8 wherein the resilient means includes a resilient diaphragm sealing the passage along a particular periphery and the adjustably positioned means includes a pusher rod disposed against the diaphragm at a position within the area encompassed by the button and further includes a knob pressing the pusher rod against the diaphragm and rotatable to adjust the force exerted by the pusher rod against the diaphragm.

10. The combination set forth in claim 8 wherein the button is provided with a looped configuration and is disposed around one of the inlet and outlet lines.

11. The combination set forth in claim 10 wherein the channel is disposed in the button at a position between the inlet and outlet lines.

12. In combination for controlling the rate of flow of intravenous fluid to a patient, a cassette, means defining a passage in the cassette for the flow of fluid, resilient means defining in the cassette a particular boundary of the passage for controlling the size of the passage in accordance with variations in force exerted against the re-silient means, means disposed in the cassette and defining an inlet to the passage and an outlet from the passage, manually operable control means extending through the cassette from a position outside of the cassette into direct engagement with the resilient means for producing an adjustable force against the resilient means in a direction to limit the size of the passage in accordance with such manual operation, a housing constructed to support the cassette, means disposed on the housing and settable to any desired rate of fluid flow, and means disposed in the housing and operatively coupled to the control means and to the settable means and responsive to any setting of the settable means for overriding any manual positioning of the control means to position the control means in accordance with such setting.

13. The combination set forth in claim 12 wherein the manually adjustable means include a plug member and a known threadedly disposed on the plug member and the settable means and the overriding means are disposed in a system for providing a controlled flow of drops of the intravenous fluid to the patient at a rate dependent upon the setting of the settable means and wherein the cassette is removable from the housing to provide for the flow of fluid through the passage in accordance with the manual adjustment of the control means.

14. The combination set forth in claim 13 wherein the resilient means are constructed to be constrained in a direction transverse to the direction of fluid flow to limit the size of the passage and wherein the passage is defined by a button blocking the passage of the fluid between the inlet and outlet lines and the button is provided with a least one channel to provide for a controlled flow of fluid.

15. The combination set forth in claim 13 wherein the channel in the button is substantially V-shaped and the over-riding means include a drive member disposed to become coupled to the the control means and the control means are constructed to be driven by the drive member and the overriding means further include a motor for driving the drive member and means for controlling the operation of the motor to obtain a drive of the drive member to a position dependent upon the setting of the settable means.

16. In combination for controlling the flow of fluid from a source to a patient, a housing an inlet line in the housing, an outlet line in the housing, a cavity in the housing in communication with the inlet and outlet lines, a resilient diaphragm disposed in the cavity to define a particular boundary of a passage extending between the inlet and outlet lines, means extending into the cavity from a position external to the housing and coupled to the diaphragm to constrain the diaphragm in accordance with the operation of the coupling means.
a button disposed between the inlet and outlet lines and blocking the passage against the flow of fluid between the inlet line and the outlet line, and means operably associated with a particular one of the button, the diaphragm and the coupling means and cooperating with at least another one of the button, the diaphragm and the coupling means to define a channel for a controlled flow of fluid through the inlet line, the passage and the outlet line.

17. The combination set forth in claim 16 wherein the channel is disposed in the button and wherein the coupling means constitutes a rod disposed against the diaphragm and adjustably positioned to constrian the diaphragm for controlling the size of the package.

18. The combination set forth in claim 17 wherein the button is disposed in a closed loop around one of the inlet and outlet lines and the channel is provided in the buttom at a position between the inlet and outlet lines.

:

19. The combination set forth in claim 16 wherein the channel is disposed in the diaphragm at a position facing the button.

20. The combination set forth in claim 16 wherein the coupling means constitutes a rod disposed against the diaphragm and the channel is disposed in the rod at a position facing the diaphragm.

21. The combination set forth in claim 17 wherein the button has a recessed portion and the channel is disposed in the recessed portion of the button and the inlet and outlet lines are disposed outwardly from the button.

22. In combination for controlling the flow of fluid from a source to a patient, means providing settings of desired rates of fluid flow, means for providing for the flow of the fluid from the source to the patient, means for sensing the rate at which the fluid flows from the source to the patient, means responsive to the settings of the desired rate of fluid flow and to the sensings of the actual rate of flow fluid for producing error signals having characteristics representing any differences in the desired and actual rates, means including an adjustably positioned member for controlling the rate of flow of the fluid through the control means in accordance with the adjustable positioning of the member, means for removably receiving the control means, and means responsive to the error signal, with the control means disposed in the receiving means, for adjusting the position-ing of the member to minimize the error signal.

23. The combination set forth in claim 22 wherein the control means includes a drive member for engaging the adjustably positioned member to adjust the position of the adjustably posi-tioned member and further includes a motor responsive to the error signal for driving the drive member in a direction to mini-mize the error signal.

24. The combination set forth in claim 23 wherein the control means defines a passage for the flow of fluid and a resilient member is disposed in the passage for controlling the size of the passage in accordance with the constraint of the re-silient member and the adjustably positioned means adjustably constrains the resilient member in the passage in accordance with adjustments in its positioning.

25. The combination set forth in claim 1 wherein the means defining the inlet and outlet lines and the passage and the adjustably positioned means are disposed in a cassette and the cassette includes the passage for receiving fluid from the inlet line and passing fluid to the outlet line and the error signal means includes transducer means for sensing the rate of flow of fluid through the passage.

26. In combination for controlling the flow of fluid from a source to a patient, means providing settings of desired rates of fluid flow, means for providing for the flow of the fluid from the source to the patient, means for sensing the rate at which the fluid flows from the source to the patient, means responsive to the settings of the desired rate of fluid flow and to the sensings of the actual rate of fluid flow for producing error signals having characteristics representing any differences in the desired and actual rates, housing means, the flow means including a cassette removably disposed in the housing means for controlling the flow of fluid from the source, means including an adjustably positioned member included in the cassette for controlling the rate of flow of the fluid through the control means and the cassette in accordance with the adjustable positioning of the member, and means responsive to the error signal for adjusting the positioning of the adjustably positioned member in a direction to minimize the error signal.

27. The combination set forth in claim 26 wherein the control means includes a plug member defining a passage and further includes resilient means disposed in the passage to control the size of the passage in accordance with the constraint of the resilient means and operatively coupled to the adjustably position-ed member to become constrained in accordance with adjustments in the positioning of the member.

28. The combination set forth in claim 27 wherein the adjusting means includes a drive member coupled to the adjustably positioned means and further includes a motor operatively coupled to the drive member and responsive to the error signal for driving the drive member in a direction to minimize the error signal.

: .:

29. The combination set forth in claim 1 wherein the means defining the inlet and outlet lines and the passage and the adjustably positioned means are disposed in a cassette and the cassette includes the passage for receiving fluid from the inlet line and passing fluid to the outlet line and the error signal means include transducer means for sensing the rate of flow of fluid through the passage.

30. The combination set forth in claim 29 wherein resilient means are disposed in the cassette to define the passage and wherein the adjustably positioned member constrains the resilient means to control the size of the passage and wherein means are responsive to the signals from the transducer means for adjusting the constraint of the adjustably positioned means against the resilient means.

31. The combination set forth in claim 5 wherein the channel in the button is substantially V-shaped.

32. The combination set forth in claim 8 wherein the channel is substantially V-shaped.

33. The combination set forth in claim 29 wherein the adjustably positioned member is manually adjustable to control the rate of fluid flow and wherein the positioning means overrides the manual adjustment of the adjustably positioned means to adjust the positioning of the member to minimize the error signal.

34. In combination for controlling the rate of flow of fluid to a patient, means for providing for a source of fluid, means defining an inlet line from the source and an outlet line to the patient, means disposed between the inlet line and the outlet line for defining a passage communicating with the inlet and outlet lines, a button disposed in the passage in blocking relation-ship to the flow of fluid through the passage between the inlet and outlet lines, there being at least one channel in the external surface of the button, resilient means disposed in the passage at a position facing the button for controlling the size of the passage in accordance with the positioning of the resilient means in the passage relative to the button, and adjustably positioned means disposed in coupled relation-ship to the resilient means for constraining the resilient means to control the size of the passage in accordance with adjustments in the positioning of the adjustably positioned means.

35. The combination set forth in claim 34 wherein the inlet and outlet lines are disposed on the same side of the passage and the resilient means faces the inlet and outlet lines.

36. The combination set forth in claim 35 wherein the channel is substantially V-shaped and the resilient means constitutes a diaphragm adjustably disposed in the V-shaped channel in accordance with constraints imposed upon the diaphragm.

37. The combination set forth in claim 36 wherein the fluid means, the inlet line, the outlet line, the passage, the button and the resilient means are disposed in a cassette and the adjustably positioned means extends from the cassette for manual adjustment.