IV pump

• US 3,985,133 A
• Filed: 05/28/1974
• Issued: 10/12/1976
• Est. Priority Date: 05/28/1974
• Status: Expired due to Term

• Current Assignee: ALARIS Medical Systems, Inc. (Becton, Dickinson & Co)
• Original Assignee: IMED Corp (Becton, Dickinson & Co)
• Inventors: Hyman, Oscar E., Flatten, Orris H., Jenkins, Jon Arthur
• Primary Examiner(s): Truluck, Dalton L.
• Application Number:
  US05/473,901
• Time in Patent Office: 868 Days
• Field of Search: 128/214 R, 128/214 B, 128/214 E, 128/214 F, 128/214.2, 128/203, 128/234, 128/218 A, 128/218 G, 128/273, 128/DIG. 1, 128/DIG. 12, 128/DIG. 1 3, 417/415, 417/12, 417/419, 417/519, 417/360, 222/59, 222/70
• US Class Current: 604/67
• CPC Class Codes: A61M 5/172 electrical or electronic A61M5/16804, A61M5/16831 take precedence
• CPC Class Codes: A61M 5/365 Air detectors A61M5/1684 takes precedence; in extracorporeal blood circuits A61M1/3626
• CPC Class Codes: Y10S 128/12 Pressure infusion

Abstract

A volumetric infusion pump for intravenous administration of fluid to a patient, including a volumetric cassette for receiving fluid from an IV fluid container and for pumping such fluid at a controlled rate using an IV administration set until a predetermined volume of fluid has been infused into the patient. The volumetric cassette contains, when filled, a predetermined volume of fluid. The cassette, when coupled to a driving mechanism in the pump, provides for the fluid to be pumped from the cassette at a predetermined rate. Once the cassette chamber has been at least partially emptied a predetermined amount by the operation of the pump, the volumetric chamber of the cassette is rapidly filled and the pumping continues with such emptying and filling of the cassette chamber alternately occurring until the predetermined volume of fluid has been pumped. The cassette is of a syringe type having a chamber and a plunger piston and the stroke of the plunger is controlled by the driving mechanism of the pump. A plurality of alarm mechanisms provide safety in the operation of the pump and provide output indications to give the operator a diagnosis of the reason that the pump has been alarmed. These alarms include air-in-line, low battery, occlusion of the line, and infusion complete.

Claims

1. A volumetric pump for pumping between a patient and a source a volume of fluid at a preselected controlled rate until a preselected volume of fluid has been pumped, including

an output line,

volumetric means for receiving the volume of fluid from the source and providing the fluid to the output line,

the volumetric means including a chamber of a predetermined volume per increment of displacement which predetermined volume is a fraction of the volume of fluid from the source and a fraction of the fluid to be pumped to the output line,

a plunger movable within the chamber on an incremental basis in a first direction for filling the chamber and movable within the chamber, in a second direction opposite to the first direction, on an incremental basis for emptying the chamber,

plunger means coupled to the plunger for driving the plunger on the incremental basis in the first direction to fill the chamber and for driving the plunger on an incremental basis in the second direction to empty the chamber,

a stepper motor constructed to operate in increments each representative of a particular distance,

control means, including the stepper motor, operatively coupled to the plunger driving means to obtain an incremental operation of the plunger driving means for driving the plunger on the incremental basis in the first direction and to obtain an incremental operation of the plunger driving means for driving the plunger on an incremental basis in the second direction,

means for providing an indication representing the preselected amount of fluid to be supplied between the patient and the source,

means responsive to the incremental operation of the plunger driver means in driving the plunger on an incremental basis in the second direction for counting the number of such incremental operations to obtain a determination of the amount of fluid transferred between the source and the patient, and

means responsive to the count of the incremental operations representing the determination of the amount of fluid transferred between the patient and the source for interrupting the supply of the fluid between the patient and the source when the amount of such fluid corresponds to a preselected incremental count.

2. The volumetric pump of claim 1 additionally including means included in the control means for obtaining an operation of the plunger driving means through the particular count of the incremental operations of the stepper motor to provide a precise control of the preselected volume of fluid pumped between the patient and the source.

3. The volumetric pump of claim 2 wherein alarm means are provided and means are included for detecting air in the output line from the volumetric means and for activating the alarm means upon such detection and where means are included for automatically interrupting the pumping of fluid upon such detection.

4. The volumetric pump of claim 3 wherein the means to detect the air in the output line from the volumetric means includes light emitter means to direct light toward the output line from the volumetric means and light detector mean to detect changes in the light passing through the output line from the volumetric means in accordance with the presence of air in the output line and wherein the light detector means is disposed relative to the light emitting means to receive light refracted by air in the output line and wherein the alarm means are responsive to an activation of the light detector means by the air refracted in the output line.

5. The volumetric pump of claim 2 additionally including means for detecting the pumping of the preselected volume of fluid in accordance with the count of the incremental operations of the stepper motor and means responsive to such detection for providing a pumping of the fluid at a preselected low rate to maintain fluid communication between the patient and the source.

6. The volumetric pump of claim 1 additionally including adjustable means for providing for an adjustment in the incremental rate of operation of the stepper motor and means responsive to adjustments in the adjustable means for instantaneously adjusting the incremental rate of operation of the stepper motor in accordance with such adjustments.

7. The volumetric pump of claim 6 additionally including means coupled to the control means for counting the incremental operations of the stepper motor during each movement of the plunger in the first direction and for adjusting the rate of incremental operation of the stepper motor in driving the plunger in the second direction, during the next movement of the plunger in the second direction, to compensate for the time lost in driving the plunger in the first direction and to maintain the rate of transfer of the fluid between the patient and the source at the preselected controlled rate.

8. The volumetric pump of claim 1 wherein the control means are operative to produce a pulse drive stepping signal at a particular rate directly related to the preselected controlled rate and wherein the stepper motor is responsive on an incremental basis to each pulse drive stepping signal from the control means to drive the plunger on an incremental basis.

9. The volumetric pump of claim 1 additionally including means responsive to the pulse drive stepping signal during the operation of the stepper motor in driving the plunger in the first direction for accumulating such stepping signals during each movement of the plunger in the first direction and for introducing such additional pulse drive stepping signals to the stepper motor during the next movement of the plunger in the second direction to compensate for the failure of the pump to pump fluid during the operation of the plunger driving means in driving the plunger in the first direction.

10. The volumetric pump of claim 8 additionally including means for comparing the rate of the pulse drive stepping signal with the incremental operation of the stepper motor to monitor the proper operation of the stepper motor in accordance with the rate of the pulse drive stepping signals and means for stopping the operation of the stepper motor when the operation of the stepper motor is not in accordance with the rate of the pulse drive stepping signal.

11. The volumetric pump of claim 1 wherein the volumetric means is a disposable cassette and the plunger is disposed in the cassette and wherein means are included for retaining the cassette in position for pumping fluid and for providing for a quick removal of the cassette from the pump for a replacement of the cassette and wherein means are also included for providing a quick disconnect of the plunger driving mechanism from the plunger.

12. The volumetric pump of claim 11 wherein the additional means includes at least a pair of pins in one of the cassette and the pump to engage a complementary pair of openings in the other one of the cassette and the pump to snap the cassette in position into a particular relationship with the pump.

13. The volumetric of claim 11 wherein the volumetric cassette includes a valve mechanism movable between first and second positions and operative in the first position to provide for the flow of fluid between the pump and one of the patient and the source and operative in the second position to provide for the flow of fluid between the pump and the other one of the patient and the source.

14. The volumetric pump of claim 13 including valve position detector means to detect the positioning of the valve mechanism in the individual ones of the first and second positions and coupled to the control means to control the operation of the plunger driving means in the individual ones of the first and second positions in driving the plunger in the respective ones of the first and secnd directions.

15. The volumetric pump of claim 14 additionally including detector means for detecting the movement of the plunger to limit positions in the chamber during the movements of the plunger in the first and second directions and means responsive to such detections for interrupting the stepper motor in driving the plunger in the direction represented by such detections and for reversing the operation of the stepper motor.

59. The combination recited in claim 1, including,

means responsive to the operation of the plunger driving means in driving the plunger in the first direction for counting such increments in the operation of the plunger driving means,

means responsive to the count of the increments from the last mentioned means for adding such count to the preselected count, and

means for interrupting the operation of the plunger driving means when the count of the increments in the operation of the plunger driving means corresponds to the count from the last mentioned means.

16. A volumetric pump for pumping fluid from a source to an output line using a volumetric cassette for receiving fluid from the source and providing fluid to the output line where the cassette includes a chamber of a predetermined volume which is a fraction of volume of fluid in the source and also a fraction of the volume of the fluid to be pumped from the source and where the cassette also includes a plunger movable within the chamber for filling the chamber during movement of the plunger in a first direction and emptying the chamber during movement of the plunger in a second direction opposite to the first direction, including

a stepper motor constructed to be operated in increments each representing a particular distance,

plunger driving means, including the stepper motor, operatively coupled to the plunger in the cassette for alternately driving the plunger in the first and second directions through the particular increments of distance,

control means coupled to the plunger driving means to control the plunger driving mechanism, with the control means including

first means for producing the incremental operation of the stepper motor at a controlled rate to obtain incremental movements of the plunger in each of the first and second directions,

second means for monitoring the count of the incremental operations of the stepper motor in driving the plunger in the second direction to control the volume of fluid pumped from the cassette chamber,

the second means including third means operative to preselect a digital count representating a particular amount of fluid to be transferred from the source to the output line,

the second means further including fourth means for counting the increments in the operation of the stepper motor in driving the plunger in the second direction, and

the second means further including fifth means operatively coupled to the third means and the fourth means for interrupting the operation of the stepper motor when the count in the fourth means corresponds to the count in the third means.

17. The volumetric pump of claim 16 wherein an output line extends from the cassette chamber and wherein means are included to detect air in the output line from the cassette and to activate an alarm upon such detection and wherein means are responsive to the detection of air in the output line for stopping the pumping of fluid from the cassette.

18. The volumetric pump of claim 17 wherein the means to detect the air in the output line from the cassette includes a light emitter to direct light toward the output line from the cassette and a light detector responsive to refracted light passing from the output line to detect changes in the refracted light resulting from the presence of air in the output line.

19. The volumetric pump of claim 16 additionally including means responsive to the operation of the fifth means in detecting the correspondence in the counts in the third and fourth means for adjusting the control means to provide for an operation of the stepper motor at a preselected low predetermined rate to keep open the pumping of the fluid from the cassette chamber after the preselected volume of fluid has been pumped.

20. The volumetric pump of claim 16 additionally including adjustable means for providing for a preselection of a particular rate of pumping of fluid and means responsive to the preselected rate provided by the adjustable means for operating the plunger driving means on an incremental basis at such rate.

21. The volumetric pump of claim 20 additionally including means coupled to the control means for measuring the time of movement of the plunger in the first direction and means for adjusting the rate of incremental operation of the plunger driving means in the second direction to compensate for the time of movement of the plunger in the first direction.

22. The volumetric pump of claim 16

wherein the stepper motor is operative on an incremental basis in driving the plunger in the first direction and wherein sixth means are operative to add to the preselected count in the third means the increments of operation of the stepper motor in driving the plunger in the first direction and wherein the fourth means is operative to count the increments in the operation of the stepper motor in driving the plunger in the first direction and wherein the fifth means is operative to interrupt the transfer of fluid from the source to the output line when the count from the fourth means corresponds to the adjusted count provided by the sixth means.

23. The volumetric pump of claim 16 wherein the control means produces a pulse drive stepping signal and the plunger driving mechanism includes a stepping motor responsive to the pulse drive stepping signal to drive the plunger on an incremental basis in the second direction.

24. The volumetric pump of claim 16 additionally including means for detecting the movements of the plunger to limit positions in the first and second directions and means responsive to the detection of the movements of the plunger to the limit positions for interrupting the operation of the plunger driving means in driving the plunger in the direction represented by the limit position detected.

25. In apparatus for use in a pump for pumping fluid from a source through a cassette and to an output line at a preselected controlled rate on an incremental basis until a preselected volume of fluid has been pumped where the pump includes a stepper motor and a driving mechanism operative by the stepper motor for controlling the filling of the cassette and for controlling at least partial emptying of the cassette on the incremental basis at the controlled rate and the driving mechanism includes a shuttle and where the pump further includes a valve control mechanism having first and second states of operation for controlling the supply of fluid from the source to the cassette in the first state of operation and the flow of fluid from the cassette to the output line in the second state of operation and further includes detent means, the cassette including

a unitary housing constructed to be handled manually for coupling to the driving mechanism and the valve control mechanism,

a chamber fixedly disposed on the housing and provided with a predetermined volume per unit of length which predetermined volume is a small fraction of the fluid in the source and a fraction of the fluid to be transferred between the source and the individual,

a plunger movable linearly and incrementally within the chamber in first and second opposite directions for coupling to the driving mechanism in the pump in accordance with the manual positioning of the housing for at least partially filling the chamber with the fluid during the linear and incremental movement of the plunger in the first direction and for at least partially emptying the chamber of a predetermined amount of the fluid upon each linear and incremental movement of the plunger in the second direction,

the plunger including means for engaging the shuttle on the pump to provide for a linear and incremental movement of the plunger in the first and second opposite directions by the driving mechanism,

first and second lines fixedly disposed on the housing in communication with the chamber, the first line also being disposed for communication with the source in the first state of operation of the valve control mechanism and the second line also being disposed for communication with the output line in the second state of operation of the valve control mechanism,

a valve mechanism constructed to cooperate with the valve control mechanism in providing the first and second states of operation and fixedly disposed on the housing between the first and second lines and in communication with the first and second lines and the chamber for coupling to the valve control mechanism in accordance with the manual positioning of the housing for providing for the flow of fluid from the chamber to the source and preventing the coupling of the chamber to the output line in the first state of operation of the valve control mechanism and for coupling the chamber to the output line and preventing the coupling of the chamber to the source in the second state of operation of the valve control mechanism, and

detent means included in the cassette for engaging the detent means in the pump to couple the cassette to the pump in a particular relationship in accordance with the manual positioning of the housing in fixed relationship to the pump means to obtain the pumping of fluid by the pump through the cassette.

26. In apparatus as set forth in claim 25 where the detent means on the pump includes a pair of spaced pins, the detent means in the cassette including a pair of holes for receiving the pins.

53. In apparatus as set forth in claim 25, the chamber being provided with a relatively short length in the direction of movement of the plunger in comparison to the width of the chamber and the chamber being provided with a substantially constant cross sectional area in the direction of its width at the different positions along the length of the chamber.

54. In apparatus as set forth in claim 25 where the pump has detent means disposed in a first direction transverse to the direction of movement of the plunger and spaced from each other in a second direction transverse to the direction of movement of the plunger, the cassette having detent means for cooperation with the detent means in the pump and the plunger including means for coupling to the driving mechanism in a direction transverse to the direction of movement of the plunger.

55. In apparatus as set forth in claim 54 where the detent means in the pump constitutes a pair of spaced pins, the detent means in the cassette constituting a pair of holes for receiving the pins.

56. In apparatus as set forth in claim 55, the chamber being provided with a relatively short length in the direction of movement of the plunger in comparison to the width of the chamber and the chamber being provided with a substantially constant cross sectional area in the direction of its width at different positions along the length of the chamber.

60. In the apparatus set forth in claim 25,

the valve control mechanism being rotatable between first and second positions and being operable in the first state in the first position and being operable in the second state in the second position.

27. A volumetric pump for pumping fluid from a source to an output line at a preselected controlled rate until a preselected volume of fluid has been pumped, including

volumetric means for receiving fluid from the source of fluid and providing fluid to the output line, and including

a chamber in the volumetric means of a predetermined volume per unit of length, which predetermined volume is a fraction of the volume of fluid in the source and a fraction of the fluid to be pumped to the output line,

a plunger movable within the chamber in a first direction for filling the chamber with fluid and movable in the chamber in a second direction opposite to the first direction for at least partially emptying the chamber,

a plunger driving mechanism coupled to the plunger for driving the plunger in the first direction to fill and in the second direction at least partially empty the chamber,

the plunger driving mechanism including

a stepper motor constructed to provide movements on an incremental basis in first and second opposite directions where each incremental movement constitutes a particular distance, the stepper motor being operatively coupled to the plunger driving mechanism to drive the plunger driving mechanism in the first and second directions through the incremental distances in accordance with the incremental operation of the stepper motor in the first and second directions,

control means coupled to the stepper motor for controlling the operation of the stepper motor and including

first means for obtaining an operation of the stepper motor at a controlled rate on an incremental basis in the second direction to at least partially empty the chamber by a predetermined volume at a preselected rate until the chamber is at least partially empty and for obtaining the operation of the stepper motor on an incremental basis in the first direction to refill the cassette, and

second means for monitoring the operation of the stepper motor in the second direction to count the number of incremental operations of the stepper motor in the second direction and thereby to determine the volume of fluid pumped from the cassette,

third means adjustable to provide a count representative of a preselected volume of fluid,

fourth means including a first diagnostic alarm coupled to the second means and the third means for providing an alarm when the count indicated by the second means to represent the volume of fluid corresponds to the count in the third means to represent the preselected volume of fluid, and

fifth means including a second diagnostic alarm for monitoring the plunger driving mechanism for detecting the driving of the plunger in the second direction on an incremental basis at a rate less than the preselected rate and for providing an alarm upon such detection.

28. The volumetric pump of claim 27 wherein a fluid line is provided between the source and the volume means and the fifth means is constructed to provide an alarm upon an occulsion of the fluid line or the output line from the volume means.

29. The volumetric pump of claim 27 additionally including means responsive to the provision of the alarm by the fourth means for adjusting the control means to obtain an operation of the stepper motor at a low predetermined rate of pumping to maintain the pumping through the output line after the preselected volume has been pumped.

57. The volumetric pump set forth in claim 27 wherein sixth means are operative to detect the time for the operation of the plunger driving mechanism in driving the plunger in the dirst direction and seventh means responsive to the time detected by the third means for adjusting the preselected volume of fluid represented by the third means in accordance with such time detection.

58. The volumetric pump set forth in claim 27 wherein sixth means are operative to detect the time for the plunger driving mechanism in driving the plunger in the first direction and seventh means are operative for adjusting the operation of the first means to vary the rate of incremental movement of the plunger in the second direction in accordance with such time detection.

30. A battery operated volumetric pump for pumping fluid dispensed from a source of fluid to an output line at a preselected controlled rate, including

a battery,

a volumetric cassette for receiving fluid from the source of fluid and providing fluid to the output line, and including

a chamber of a predetermined volume per unit of length and with a total volume which is a fraction of the source of fluid and a fraction of the volume of fluid to be dispensed from the source, the cassette also including a plunger movable within the chamber for filling and at least partially emptying the chamber a predetermined amount upon movement of the plunger in alternate directions, and

a stepper motor constructed to operate in first and second opposite directions in increments each representing a particular distance, the stepper motor being operatively coupled to the battery to be energized by the battery,

a plunger driving mechanism, including the stepper motor, coupled to the plunger for driving the plunger on an incremental basis in alternate directions to fill and at least partially empty the chamber,

control means coupled to the plunger driving mechanism for controlling the operation of the stepper motor to alternately drive the plunger on an incremental basis at a controlled speed in one direction to at least partially empty the cassette chamber a predetermined amount at a preselected rate until the chamber is at least empty and to drive the plunger on an incremental basis in the opposite direction to refill the cassette,

detector means coupled to the battery for detecting the voltage level across the battery, and

an alarm mechanism coupled to the detector means for actuating an alarm upon the detection of a voltage level of the battery below a preselected value.

31. The volumetric pump of claim 30 additionally including means for preselecting a rate of incremental operation of the stepper motor in the first direction and means coupled to the control means for counting the number of increments of operation of the stepper motor in the direction for refilling the cassette chamber during each operation of the stepper motor in that direction and for adjusting the rate of the incremental operation of the stepper motor in the first direction, during the next operation of the stepper motor in that direction, to empty the cassette chamber at a rate higher than the rate preselected for the incremental operation of the stepper motor in that direction to compensate for the time lost in refilling the cassette chamber.

32. A volumetric pump for pumping fluid dispensed from a source of fluid to an output line at a preselected controlled rate until a preselected volume of fluid has been pumped, including

a volumetric cassette for receiving fluid from the source of fluid and providing fluid to the output line, and including

a chamber of a predetermined volume per unit of length and with a total volume which is a fraction of the source of fluid and a fraction of the volume of fluid to be dispensed to the output line, the cassette also including a plunger movable within the chamber in a first direction for filling the chamber with fluid and movable within the chamber in an opposite direction for at least partially emptying the chamber of the fluid,

a stepper motor constructed to operate on an incremental basis in first and second opposite directions where each increment represents a particular displacement

a plunger driving mechanism, including the stepping motor, coupled to the plunger for driving the plunger on an incremental basis in alternate directions in accordance with a pulse drive stepping signal to fill and at least partially empty the chamber and wherein a predetermined number of incremental operations of the stepper motor equal a unit quantity of fluid pumped and the rate of the fluid pumped is in accordance with the rate of introduction of the pulse drive stepping signal,

means for adjusting the rate of the pulse drive stepping signal in accordance with the preselected controlled rate,

control means coupled to the plunger driving mechanism for providing a pulse drive stepping signal at a particular rate for controlling the plunger driving mechanism to alternately drive the plunger on an incremental basis in the first direction at a controlled speed in accordance with the rate of the pulse drive stepping signal to at least partially empty the cassette chamber a predetermined amount at a preselected rate and to drive the plunger on an incremental basis in the opposite direction to refill the cassette,

means for providing a preselected count of the number of increments of operation of the stepper motor in the opposite direction,

means operatively coupled to the stepper motor for counting the number of incremental operations of the stepper motor in the opposite direction, and

means operatively coupled to the last two mentioned means for comparing the count in the last two mentioned means to interrupt the operation of the stepper motor when the counts coincide.

33. The volumetric pump of claim 32 additionally including means responsive to the pulse drive stepping signal during each refilling of the cassette chamber for counting the number of the pulse drive stepping signal during each such refilling and means responsive to such count for changing the preselected count in accordance with such count.

35. The volumetric pump of claim 32 additionally including means for comparing the rate of the pulse drive stepping signal with the rate of incremental operation of the stepper motor to monitor the incremental operation of the stepper motor in accordance with the pulse drive stepping signal and including means responsive to such comparison for interrupting the incremental operation of the pump at the preselected controlled rate when the incremental operation of the stepper motor is not in accordance with the rate of the pulse drive stepping signal.

34. The volumetric pump of cllaim 32 additionally includes means responsive to the pulse drive stepping signal during each refilling of the cassette chamber for counting the number of the pulse drive stepping signal during each such refilling and for providing an additional count in the pulse drive stepping signal corresponding to such count during the next operation of the stepper motor in the opposite direction for compensating the rate of pumping the fluid to the output line to equal the preselected rate.

36. A volumetric pump for pumping fluid dispensed from a source of fluid to an output line at a preselected controlled rate including

a volumetric cassette for receiving fluid from the source of fluid and providing fluid to the output line, and including

a chamber of a predetermined volume per unit of length and of a total volume which is a fraction of the source of fluid and a fraction of the fluid to be dispensed to the output line, the cassette also including a plunger movable in a first direction within the chamber for filling the chamber with the fluid and also movable within the chamber in an opposite direction for at least partially emptying the chamber of the fluid,

a plunger driving mechanism coupled to the plunger for alternately driving the plunger in the first and opposite directions respectively to fill and at least partially empty the chamber, and

the plunger driving mechanism including a stepper motor constructed to operate on an incremental basis in first and second opposite directions to provide particular incremental displacements in such directions in accordance with the incremental operations of the stepper motor,

a valve mechanism to control the flow of fluid to and from the cassette chamber during filling and at least partial emptying of the cassette chamber, the valve mechanism having first and second positions and being synchronized in operation between the first and second positions in accordance with the operation of the stepper motor to provide for a flow of fluid to the chamber during the incremental operation of the stepper motor in driving the plunger in the first direction and to provide for a flow of fluid from the chamber during the incremental operation of the stepper motor in driving the plunger in the second direction, and

control means coupled to the plunger driving mechanism to control the stepper motor to alternately drive the plunger at a controlled rate in the second direction, with the valve mechanism in the first position, to at least partially empty the cassette chamber at a preselected rate until the chamber is at least partially empty, and to drive the plunger in the first direction, with the valve mechanism in the second position, to refill the cassette.

37. The volumetric pump of claim 36 additionally including valve position detector means included in the control means to control the direction of movement of the plunger driving mechanism and to control the movement of the valve mechanism between the first and second positions.

38. The volumetric pump of claim 37 additionally including means operatively coupled to the stepper motor for counting the incremental operations of the stepper motor in driving the plunger in the first direction during each movement of the plunger in the first direction and means operatively coupled to the stepper motor for increasing the incremental operation of the stepper motor, during the next operation of the stepper motor in driving the plunger in the second direction, by a count corresponding to the count of the incremental operations of the stepper motor in driving the plunger in the first direction during the previous movement of the plunger in the first direction.

39. Apparatus for use in a pump for pumping fluid between a source and an individual at a controlled rate where the pump includes a stepper motor and first means operatively coupled to the stepper motor for moving linearly and incrementally and for pumping fluid in accordance with such linear and incremental movement and includes a shuttle on the first means and where the pump further includes second means for controlling the pumping of the fluid between the source and the individual and having first and second states of operation and further includes third means for providing detents, such apparatus including,

a hollow chamber having a particular volume per unit of length and having first and second conduits and having a volume considerable less than the volume of fluid to be transferred between the source and the individual, the chamber being disposed to provide for the passage of fluid between the source and the chamber through the first conduit and to provide for the passage of such fluid between the chamber and the individual through the second conduit, the chamber and the first and second conduits being disposed and constructed to provide for the passage of the fluid between the source and the chamber and between the chamber and the individual without contacting the pump or the first means or the second means,

a plunger disposed in the chamber for coupling to the first means in a particular relationship for linear and incremental movement by the first means in a first direction to provide for the passage of the fluid through the first conduit between the chamber and the source and for linear and incremental movement in a second direction opposite to the first direction to provide for the passage of the fluid between the chamber and the individual, the plunger means being constructed to be engaged by the shuttle on the first means in the pump to provide for a positive drive of the plunger by the first means,

a valve disposed in communication with the chamber and in fixed relationship with the chamber and in communication with the first and second conduits for coupling to the second means in a particular relationship and cooperative with the second means in the coupled relationship for providing the first and second states of operation to provide for a flow of the fluid between the source and the chamber through the first conduit and to prevent the flow of fluid between the chamber and the individual through the second conduit in the first state of operation of the second means and to provide for a flow of the fluid between the chamber and the individual through the second conduit and to prevent the flow of the fluid between the source and the chamber through the first conduit in the second state of operation of the second means, and

coupling means disposed in fixed relationship with the chamber for fixed coupling to the third means in the pump to provide for a coupling of the plunger to the first means and a coupling of the valve to the second means and thereby to provide for a controlled transfer of the fluid between the source and the individual in accordance with the operation of the second means in the first and second states.

40. The combination set forth in claim 39 wherein the coupling means includes

means operatively coupled to the chamber to provide for a particular coupling between the valve and the second means in the pump to provide for a controlled operation of the valve between the first and second positions by the second means.

41. The combination set forth in claim 39 wherein the coupling means includes

means operatively coupled to the chamber to provide for a particular coupling between the plunger and the first means in the pump to provide for an operation of the plunger by the first means.

42. The combination set forth in claim 41 wherein the coupling means includes detent means provided on the pump and

detent means operatively coupled to the chamber to cooperate with detent means on the pump to provide for a quick coupling of the chamber to the pump in fixed disposition on the pump and to provide for a quick disconnect of the chamber from the pump.

61. Apparatus as set forth in claim 39 wherein the valve is rotatable between first and second positions and is operable in the first state in the first position and is operable in the second state in the second position and the second means in the pump includes a valve motor shaft rotatable between first and second positions and the valve includes a valve portion for positively engaging the valve motor shaft for rotation with the valve motor shaft when the coupling means engages the third means in the pump and the stepper motor is constructed to provide the incremental operation on an open loop basis.

43. In combination for pumping fluid between a source and an individual,

drive means including a linearly reciprocatable drive member, the reciprocatable drive member including a shuttle,

pump means operable to reciprocate the drive member on a controlled basis in the linear direction, the pump means being constructed to provide an incremental movement of the drive member in the linearly reciprocal directions with each increment representing a movement of the drive member through a particular increment of distance, the pump means including a stepper motor responsive to the introduction of pulses to provide precise increments of movement in accordance with the introduction of the pulses,

a hollow chamber having a particular volume per unit of length and having a total volume considerably less than the volume of fluid to be transferred between the source and the individual and having first and second conduits, the chamber being disposed to provide for the passage of fluid between the source and the chamber through the first conduit and to provide for the passage of fluid between the chamber and the individual through the second conduit,

a plunger disposed in the chamber for linearly reciprocating movement with the drive member on an incremental basis in a first direction to provide for the passage of the fluid through the first conduit between the chamber and the source and for linearly reciprocating movement on an incremental basis in a second direction opposite to the first direction to provide for the passage of the fluid between the chamber and the individual, the plunger including a portion for positively engaging the shuttle,

valve control means fixedly disposed in communication with the chamber and the first and second conduits and having first and second states of operation and operable in the first state to provide for a flow of fluid between the source and the chamber through the first conduit and to prevent the flow of the fluid between the chamber and the individual through the second conduit and operable in the second state to provide for the flow of fluid between the chamber and the individual through the second conduit and to prevent the flow of the fluid between the source and the chamber through the first conduit,

means responsive to the operation of the valve control means in individual ones of first and second states for providing an operation of the valve control means in the other one of the first and second states,

the hollow chamber and the plunger being physically displaced from the drive member, the pump means and the valve control means to provide for the pumping of the fluid through the chamber and the first and second conduits between the source and the individual without contacting the drive member, the pump means and the valve control means,

pulse means for providing a plurality of pulses at a variably controlled rate, the pulse means being means operatively coupled to the stepper motor to provide an incremental operation of the stepper motor at the variably controlled rate in driving the drive member in the linearly reciprocating directions through a plurality of cycles to provide for the flow of fluid into and out of the chamber at a particular rate related to the variably controlled rate of incremental operation of the stepper motor,

first adjustable means for preselecting a particular number of increments of movement of the plunger in a particular one of the linearly reciprocatable directions to control the amount of fluid to be transferred between the source and the individual,

counting means operatively coupled to the pump means for counting the number of increments of movement of the plunger in the particular one of the linearly reciprocatable directions to determine the incremental flow of fluid through the chamber at the variably controlled rate, and

means operatively coupled to the adjustable means and the counting means for interrupting the incremental operation of the stepper motor at the variably controlled rate to interrupt the flow of fluid through the chamber at the particular rate when the count provided by the counting means corresponds to the preselected amount selected by the adjustable means.

44. The combination set forth in claim 43, including,

means responsive to the movement of the drive member in the other one of the reciprocating directions for counting the number of incremental movements of the drive member in this direction, and

means responsive to the count provided by the last mentioned means for adjusting the rate of incremental operation of the pump means in driving the drive member in the particular direction to compensate for the movement of the drive member in the other one of the reciprocating directions.

45. The combination set forth in claim 43, including,

means responsive to the cumulative transfer of the preselected amount of the fluid out of the chamber for thereafter lowering the rate of transfer of fluid out of the chamber to a particular minimum level to maintain a communication between the source and the individual.

46. The combination set forth in claim 43, including,

means operatively coupled to a particular one of the first and second conduits for determining whether only the fluid is passing at each instant through the particular conduit, and

means responsive to the determination provided by the last mentioned means for instantaneously interrupting the flow of fluid through the particular conduit when the last mentioned means determines at any instant that only the fluid is not passing through the particular conduit.

47. The combination set forth in claim 43, including,

means operatively coupled to the stepper motor for determining whether the stepper motor is operating on an incremental basis at a particular rate, and

means responsive to the determination provided by the last mentioned means for interrupting the operation of the stepper motor when the stepper motor is operating on an incremental basis at a rate lower than the particular rate.

48. The combination set forth in claim 45 wherein

the pump includes a stepping motor operative on an incremental basis to drive the driving member on an incremental basis to obtain the pumping of a particular amount of fluid in each such increment and wherein

means are responsive to a movement of the driving member in the other one of the reciprocating directions for determining the number of increments in the operation of the stepping motor during such reciprocating movement and wherein

means are responsive to the determination provided by the last mentioned means for compensating, in accordance with such determination, in the rate of the incremental operation of the motor in driving the drive member in the particular one of the reciprocating directions.

52. The combination recited in claim 43, including,

the counting means including means responsive to the operation of the stepper motor in driving the drive member in the other one of the reciprocating directions for counting the number of incremental operations of the stepper motor in such other one of the reciprocal directions in each such movement of the drive member,

means responsive to the count provided by the last mentioned means for adding such count to the preselected count provided by the adjustable means, and

means responsive to the count representing the number of incremental operations of the stepper motor in driving the drive member in the other one of the reciprocal directions in each such movement of the drive member for increasing the incremental operations of the stepper motor in driving the drive member in the particular direction in the next movement of the drive member in the particular direction.

62. In the combination set forth in claim 43,

the valve being rotatable between first and second positions and being operable in the first state in the first position and being operable in the second state in the second position and the valve control means including a valve motor shaft rotatable between first and second positions and the stepper motor being constructed to provide the incremental operation on an open loop basis.

49. In combination in a cassette for use with a pump for passing fluid at a controlled rate between a source and an individual where the pump includes first means including a stepper motor of a first particular configuration and constructed to provide a flow of the fluid on an incremental basis at a particular rate and including a shuttle movable by the stepper means and includes second means of a second particular configuration and constructed to control the direction of fluid flow and detent means having a third particular configuration and constructed to provide a mating relationship,

a hollow chamber constructructed to provide a storage of limited volume relative to the volume of fluid to be transfused between the source and the individual and having first and second conduits respectively disposed for communication with the source and the individual and having a particular volume per unit of length,

a plunger movable within the chamber in opposite reciprocatory directions in sequence for an insertion of the fluid into the chamber during a movement of the plunger in one of the opposite reciprocatory directions in the sequence and to provide for a transfer of fluid from the chamber during a movement of the plunger in the other one of the opposite reciprocating directions in the sequence, the plunger including means engaging the shuttle on the basis of a quick connect and disconnect for movement by the shuttle,

the plunger including means having a configuration corresponding to the configuration of the shuttle to provide a mating relationship with the shuttle for a movement on an incremental basis of the plunger in opposite reciprocating directions by the first means,

a valve movable between first and second positions and operable in the first position to provide a communication between the source and the chamber through the first conduit and to prevent a communication between the chamber and the individual and operable in the second position to provide a communication between the chamber and the individual through the second conduit and to prevent a communication between the source and the chamber,

means having a configuration corresponding to the second particular configuration to provide a mating relationship between the means and the valve for an operation of the valve on a controlled basis between the first and second positions, and

means having a configuration corresponding to the third particular configuration to mate with the detent means on the basis of a quick connect and disconnect to provide a fixed disposition of the chamber and the plunger and valve relative to the pump.

50. The combination set forth in claim 49 wherein the detent means constitutes a pair of spaced pins on the pump and

a pair of spaced holes in the cassette to receive the pair of spaced pins.

51. The combination set forth in claim 49 wherein

the second means includes a shaft rotatable between first and second positions and wherein the valve engages the shaft and has a portion rotatable between the first and second positions to control the communication between the source and the chamber and between the chamber and the individual.