DIAPHRAGM PUMP AND RELATED SYSTEMS AND METHODS

• US 20090137940A1
• Filed: 11/26/2007
• Published: 05/28/2009
• Est. Priority Date: 11/26/2007
• Status: Active Grant

• Current Assignee: Baxter Healthcare SA (Baxter International Inc.), Baxter International Inc.
• Original Assignee: Purity Solutions ,LLC
• Inventors: Orr, Troy J.
• Granted Patent: US 8,038,640 B2
• Time in Patent Office: Days
• US Class Current: 604/6.110
• CPC Class Codes: A61M 1/16 with membranes
• CPC Class Codes: A61M 1/1698 Blood oxygenators with or without heat-exchangers intracorporal A61M1/1678; manufacturing of membranes therefor B01D67/00; semi-permeable membranes for separation processes characterised by their properties B01D69/00; semi-permeable membranes characterised by their material B01D71/00
• CPC Class Codes: A61M 1/3666 Cardiac or cardiopulmonary bypass, e.g. heart-lung machines
• CPC Class Codes: A61M 60/109 incorporated within extracorporeal blood circuits or systems
• CPC Class Codes: A61M 60/113 in other functional devices, e.g. dialysers or heart-lung machines
• CPC Class Codes: A61M 60/148 in line with a blood vessel using resection or like techniques, e.g. permanent endovascular heart assist devices
• CPC Class Codes: A61M 60/268 the displacement member being flexible, e.g. membranes, diaphragms or bladders
• CPC Class Codes: A61M 60/427 the force acting on the blood contacting member being hydraulic or pneumatic
• CPC Class Codes: A61M 60/43 using vacuum at the blood pump, e.g. to accelerate filling
• CPC Class Codes: A61M 60/531 using blood pressure data, e.g. from blood pressure sensors
• CPC Class Codes: A61M 60/554 of blood pressure
• CPC Class Codes: A61M 60/851 Valves

Abstract

In some arrangements, a pump for moving a fluid has one or more pump chambers and one or more flow control valves with diaphragm actuation regions. Motive fluid can activate the diaphragm actuation regions, and a pattern of fluid flow can be controlled by varying the pressure levels of the motive fluid.

Claims

1. A blood pumping assembly for effecting blood flow to or from a body of a patient, the assembly comprising:

a pump that includes;

a first pump chamber comprising a first diaphragm actuation region, the first diaphragm actuation region defining a first dome height in a resting state;

a second pump chamber comprising a second diaphragm actuation region, the second diaphragm actuation region defining a second dome height in a resting state;

a first and a second pressure-actuated inlet valve in fluid communication with an inlet channel, the first inlet valve configured to selectively permit blood to flow from the inlet channel to the first pump chamber, the second inlet valve configured to selectively permit blood to flow from the inlet channel to the second pump chamber; and

a first and a second pressure-actuated outlet valve in fluid communication with an outlet channel, the first outlet valve configured to selectively permit blood to flow from the first pump chamber to the outlet channel, the second outlet valve configured to selectively permit blood to flow from the second pump chamber to the outlet channel; and

a control system in fluid communication with a first source of motive fluid at a first pressure level and configured to transition between a first state and a second state, the control system configured to permit fluid communication between the first source of motive fluid and both the first inlet valve and the second outlet valve of the pump when in the first state to thereby actuate the first inlet valve and the second outlet valve, the control system configured to permit fluid communication between the first source of motive fluid and both the second inlet valve and the first outlet valve of the pump when in the second state to thereby actuate the second inlet valve and the first outlet valve.

2. The blood pumping assembly of claim 1, wherein the control system is configured to provide fluid communication between the first source of motive fluid and the first pump chamber when in the first state to thereby actuate the first pump chamber, and is configured to provide fluid communication between the first source of motive fluid and the second pump chamber when in the second state to thereby actuate the second pump chamber.

3. The blood pumping assembly of claim 1, wherein the control system is configured to simultaneously place the first source of motive fluid in fluid communication with the second pump chamber, the second inlet valve, and the first outlet valve during at least a portion of a pump cycle.

4. The blood pumping assembly of claim 1, wherein the control system is configured to transition the first inlet valve and the second outlet valve to one of an open state and a closed state and to transition the first outlet valve and the second inlet valve to the other of an open and a closed state before transitioning the first pump chamber to one of a substantially filled and a substantially emptied state and transitioning the second pump chamber to the other of a substantially filled and a substantially emptied state.

5. The blood pumping assembly of claim 1, wherein the first inlet valve, the first pump chamber, and the second outlet valve are simultaneously in fluid communications with the first source of motive fluid during a portion of the pump cycle.

6. The blood pumping assembly of claim 1, wherein the pump comprises a first substantially rigid housing component that defines at least a portion of each of the first and second pump chambers, the first housing component defining the inlet channel and the outlet channel.

7. The blood pumping assembly of claim 6, wherein the pump further comprises a second substantially rigid housing component, the second housing component defining one or more motive fluid passageways configured to permit fluid flow between the control system and one or more of the first and second inlet valves and first and second outlet valves.

8. The blood pumping assembly of claim 1, wherein the pump comprises a first and a second diaphragm, the first diaphragm comprising one or more of the first and second diaphragm actuation regions, the second diaphragm defining at least a portion of one or more of the first and second inlet valves and first and second outlet valves.

9. The blood pumping assembly of claim 1, wherein each of one or more integrated diaphragm media comprise both the first and second diaphragm actuation regions.

10. The blood pumping assembly of claim 1, wherein each of one or more of the first and second inlet valves and first and second outlet valves comprise a diaphragm actuation region that defines a dome height in a resting state.

11. The blood pumping assembly of claim 1, wherein the control system is further in fluid communication with a second source of motive fluid at a second pressure level, the control system configured to provide fluid communication between the second source of motive fluid and both the second inlet valve and the first outlet valve of the pump when in the first state to thereby actuate the second inlet valve and the first outlet valve, and wherein the control system is configured to provide fluid communication between the second source of motive fluid and both the first inlet valve and the second outlet valve of the pump when in the second state to thereby actuate the first inlet valve and the second outlet valve.

12. The blood pumping assembly of claim 11, wherein the pump is configured to be coupled with a blood source that is at a blood uptake pressure level and is configured to deliver blood to a blood delivery location that is at a blood discharge pressure level, the first pressure level of the first source of motive fluid being higher than the blood discharge pressure level, the second pressure level of the second source of motive fluid being lower than the blood uptake pressure level.

13. The blood pumping assembly of claim 11, wherein the first pressure level of the first source of motive fluid is in a range of between about 50 mmHg and about 500 mmHg and the second pressure level of the second source of motive fluid is in a range of between about −

250 mmHg and about 0 mmHg.

14. The blood pumping assembly of claim 1, wherein each of the first and second inlet valves and the first and second outlet valves comprises a diaphragm portion configured to prevent the first motive fluid from contacting blood moving through the pump when the pump is connected to the control system such that the originally connected pump can be removed from the control system and replaced with a second pump without the second pump being contaminated due to blood flow through the originally connected pump.

15. The blood pumping assembly of claim 1, wherein the diaphragm portions of the first and second inlet valves are configured to move within the first and second inlet valves between end-of-stroke positions, wherein the first and second inlet valves are configured to be actuated from an end-of-stroke position when a pressure differential on opposite sides of the diaphragm portions is between about 5 mmHg and about 200 mmHg.

16. The blood pumping assembly of claim 1, wherein the respective diaphragm portion of each the first and second inlet valves is configured to move between end-of-stroke positions, wherein the respective diaphragm portion of each of the first and second inlet valves is configured to be maintained at an end-of-stroke position when a pressure differential on opposite sides of the diaphragm portion is about 0 mmHg.

17. The blood pumping assembly of claim 1, wherein the first and second diaphragm actuation regions are configured to move within the first and second pump chambers, respectively, between end-of-stroke positions, wherein the first diaphragm actuation region approximately defines the first dome height when at an end-of-stroke position and/or the second diaphragm actuation region approximately defines the second dome height when at an end-of-stroke position.

18. The blood pumping assembly of claim 1, wherein the control system comprises a processor configured to transition the control system between the first and second states in at least one pattern to effect at least one pattern of blood flow to and from the pump selected from the group consisting of pulsatile inflow and substantially constant outflow, pulsatile inflow and pulsatile outflow, substantially constant inflow and pulsatile outflow, and substantially constant inflow and substantially constant outflow.

19. The blood pumping assembly of claim 1, wherein the control system comprises a processor configured to transition the control system between the first and second states in at least two separate patterns to separately effect at least two patterns of blood flow to and from the pump selected from the group consisting of pulsatile inflow and substantially constant outflow, pulsatile inflow and pulsatile outflow, substantially constant inflow and pulsatile outflow, and substantially constant inflow and substantially constant outflow.

20. The blood pumping assembly of claim 1, wherein the first and second dome heights are approximately equal.

21. A blood pumping system for effecting blood flow to or from a body of a patient, the system comprising:

a removable pump comprising;

a first pump chamber and a second pump chamber;

a first fluid-pressure-activated inlet valve configured to selectively permit blood to flow to the first pump chamber;

a second fluid-pressure-activated inlet valve configured to selectively permit blood to flow to the second pump chamber;

a first fluid-pressure-activated outlet valve configured to selectively permit blood to flow from the first pump chamber;

a second fluid-pressure-activated outlet valve configured to selectively permit blood to flow from the second pump chamber;

a first substantially rigid housing member defining at least a portion of the first pump chamber; and

a second substantially rigid housing member defining at least a portion of the first pump chamber; and

a reusable control base configured to selectively couple with the removable pump, the control base configured to transition between at least a first state and a second state, the control base providing motive fluid to the pump in the first state such that the first inlet valve and the second outlet valve move toward an open configuration as the first outlet valve and the second inlet valve move toward a closed configuration, the control base providing motive fluid to the pump in the second state such that the first inlet valve and the second outlet valve move toward a closed configuration as the first outlet valve and the second inlet valve move toward an open configuration.

22. The blood pumping system of claim 21, wherein the pump comprises a first diaphragm and a second diaphragm, the first housing member being between the first and second diaphragms.

23. The blood pumping system of claim 22, wherein one or more of the first and second pump chambers are at least partially defined by the first diaphragm and one or more of the first and second inlet valves and first and second outlet valves are at least partially defined by the second diaphragm, the first diaphragm configured to move relative to the first housing member to actuate said one or more of the first and second pump chambers, the second diaphragm configured to move relative to the first housing member to actuate said one or more of the first and second inlet valves and first and second outlet valves.

24. The blood pumping system of claim 22, wherein the pump further comprises a third substantially rigid housing member, the third housing member cooperating with first housing member and the second diaphragm to define one or more of the first and second inlet valves and first and second outlet valves.

25. The blood pumping system of claim 22, wherein one or more of the first and second diaphragms each comprises one or more preformed actuation regions.

26. The blood pumping system of claim 21, wherein the control base is configured to simultaneously move the first and second pump chambers such that blood enters the first pump chamber and blood exits the second pump chamber when the control base is in the first state, the control base further configured to simultaneously move the first and second pump chambers such that blood exits the first pump chamber and blood enters the second pump chamber when the control base is in the second state.

27. The blood pumping system of claim 26, wherein the control base permits fluid communication between the first source of motive fluid and the second pump chamber and permits fluid communication between the second source of motive fluid and the first pump chamber when the control base is in the first state, and the control base permits fluid communication between the first source of motive fluid and the first pump chamber and permits fluid communication between the second source of motive fluid and the second pump chamber when the control base is in the second state.

28. The blood pumping system of claim 21, wherein the control base provides fluid communication between the first source of motive fluid and the second pump chamber, the second inlet valve, and the first outlet valve and provides fluid communication between the second source of motive fluid and the first pump chamber, the first inlet valve, and the second outlet valve when in the first state, and the control base provides fluid communication between the first source of motive fluid and the first pump chamber, the first inlet valve, and the first outlet valve and provides fluid communication between the second source of motive fluid and the second pump chamber, the second inlet valve, and the first outlet valve when in the second state.

29. The blood pumping system of claim 21, wherein the first pressure level of the first motive fluid source is within a range of between about 50 mmHg and about 500 mmHg and the second pressure level of the second motive fluid source is within a range of between about −

250 mmHg and about 0 mmHg.

30. A blood pumping system comprising:

a pump comprising;

a first pump chamber;

a first pressure-actuated inlet valve configured to selectively permit blood to flow to the first pump chamber;

a first pressure-actuated outlet valve configured to selectively permit blood to flow from the first pump chamber; and

two or more substantially rigid housing members at least partially defining the first pump chamber, the first inlet valve, and the first outlet valve, the two or more substantially rigid housing members defining a plurality of motive fluid passageways in fluid communication with the first pump chamber, the first pressure-actuated inlet valve, and the first pressure-actuated outlet valve; and

a control base separate from the two or more substantially rigid housing members, the control base configured to selectively interface with the pump, the control base comprising a mounting region defining a plurality of openings, the openings configured to provide motive fluid to the plurality of motive fluid passageways, wherein at least a first and a second motive fluid passageway are configured to simultaneously couple with at least a first opening and a second opening, respectively, via movement of the pump relative to the base.

31. The blood pumping system of claim 30, wherein the control base further comprises at least one motive fluid valve in fluid communication with a first source of motive fluid, the motive fluid valve configured to transition between at least a first state and a second state, the motive fluid valve permitting fluid communication between the first source of motive fluid and the first opening in the first state and permitting fluid communication between the first source of motive fluid and the second opening in the second state.

32. The blood pumping system of claim 31, wherein the motive fluid valve is configured to transition to a shutoff state to substantially prevent fluid communication between the first source of motive fluid and the first and second openings.

33. The blood pumping system of claim 30, further comprising a second pump chamber, a second pressure-actuated inlet valve configured to selectively permit blood to flow to the second pump chamber, and a second pressure-actuated outlet valve configured to selectively permit blood to flow from the second pump chamber.

34. The blood pumping system of claim 33, wherein the control base is configured to actuate the first and second inlet valves and the first and second outlet valves such that the first pump chamber fills with blood as the second pump chamber empties.

35. The blood pumping system of claim 34, wherein the control base further comprises at least one motive fluid valve in fluid communication with a first source of motive fluid, the motive fluid valve configured to transition between at least a first state to a second state, the motive fluid valve simultaneously permitting fluid communication between the first source of motive fluid and the first opening in the first state and simultaneously permitting fluid communication between the first source of motive fluid and the second opening in the second state.

36. The blood pumping system of claim 33, further comprising a manifold configured to simultaneously provide fluid communication between a first source of motive fluid and the first inlet valve and the first pump chamber and to simultaneously provide fluid communication between a second source of motive fluid and the second inlet valve and the second pump chamber via at least one motive fluid valve.

37. The blood pumping system of claim 30, wherein the pump and the control base are configured to couple with each other in releasable engagement such that the pump can be removed from the control base and replaced with another pump of like construction.

38. The blood pumping system of claim 30, wherein each passageway of the plurality of passageways of the pump is configured to simultaneously couple with each opening of the plurality of openings of the control base via movement of the pump relative to the control base in a single direction.

39. The blood pumping system of claim 30, wherein one of the pump and the control base comprises a hook and the other of the pump and the control base comprises a latch, the hook and latch configured to cooperate to selectively connect the pump with the control base.

40. The blood pumping system of claim 30, further comprising a third substantially rigid housing member that at least partially defines one or more of the first pump chamber, the first inlet valve, and the first outlet valve.

41. The blood pumping system of claim 30, wherein one or more of the first pump chamber, the first inlet valve, and the first outlet valve comprises a diaphragm actuation region that defines a dome height when in a natural state.

42. A hemodialysis system for removing blood from a patient and returning blood to the patient, the system comprising:

a blood pump including;

a first pump chamber and a second pump chamber;

a first inlet valve configured to control the flow of blood to the first pump chamber;

a second inlet valve configured to control the flow of blood to the second pump chamber;

a first outlet valve configured to control the flow of blood from the first pump chamber; and

a second outlet valve configured to control the flow of blood from the second pump chamber;

a dialyzer in fluid communication with the blood pump;

one or more pressure sensors configured to obtain information regarding blood pressure within the system; and

a control base coupled with the pump, the control base configured to selectively provide fluid communication between a first source of motive fluid at a first pressure level and the pump, the control base configured to alternate between a first state and a second state at a cycle rate, the control base configured to provide fluid communication between the first source of motive fluid and a first portion of the pump in the first state and configured to provide fluid communication between the first source of motive fluid and a second portion of the pump in the second state,

wherein the control base is configured to receive information regarding blood pressure within the system from the one or more pressure sensors, and wherein the control base is configured to utilize the information to selectively alter one or more of the first pressure level and the cycle rate to effect a substantially constant flow of blood uptake from the patient.

43. The system of claim 42, wherein the first portion of the pump comprises the first pump chamber, the first inlet valve, and the second outlet valve and the second portion of the pump comprises the second pump chamber, the second inlet valve, and the first outlet valve.

44. The system of claim 42, wherein the control base is configured to provide fluid communication between a second source of motive fluid at a second pressure level and the second portion of the pump when in the first state and between the second source of motive fluid and the first portion of the pump when in the second state.

45. The system of claim 44, wherein the control base is configured to utilize the information regarding blood pressure within the system to selectively alter one or more of the first pressure level, the second pressure level, and the cycle rate to effect a substantially constant flow of blood uptake from the patient.

46. The system of claim 42, wherein the control base is configured to utilize the information regarding blood pressure within the system to selectively alter one or more of the first pressure level and the cycle rate to effect a pulsatile flow of blood to the dialyzer.

47. The system of claim 42, wherein the control base is configured to utilize the information regarding blood pressure within the system to selectively alter one or more of the first pressure level and the cycle rate to effect an effectively constant flow of blood return to the patient.

48. The system of claim 42, wherein the control base is configured to actuate the first and the second pump chambers such that the first pump chamber fills with blood as the second pump chamber expels blood.

49. The system of claim 42, wherein the first pump chamber comprises a first diaphragm actuation region configured to move within the first pump chamber between end-of-stroke positions and the second pump chamber comprises a second diaphragm actuation region configured to move within the second pump chamber between end-of-stroke positions, and

wherein the control base selectively alters one or more of the first pressure level and the cycle rate to prevent the first diaphragm actuation region from reaching an end-of-stroke position as the first pump chamber fills with blood and to prevent the second diaphragm actuation region from reaching an end-of-stroke position as the second pump chamber fills with blood.

50. A method of reducing air flow in an output line of a blood pump, the method comprising:

providing a blood pump comprising;

a pressure-actuated pump chamber;

an inlet channel;

an outlet channel;

an outlet valve configured to control the flow of blood from the first pump chamber to the outlet channel; and

a valve bypass channel that provides continuous fluid communication between the pump chamber and the outlet channel;

drawing a quantity of blood into the pump chamber from the inlet channel during a fill stroke of the pump chamber; and

passing a volume of air through the valve bypass channel into the pump chamber during the fill stroke such that the quantity of blood that is drawn into the pump chamber during the fill stroke is smaller than an amount of blood drawn into the pump chamber during an earlier fill stroke.

51. The method of claim 50, further comprising repeatedly filling and emptying the pump chamber such that air collected in the pump chamber in one pumping cycle is within the chamber in a subsequent pumping cycle.

52. A cardiopulmonary bypass system for removing blood from a patient and returning blood to the patient, the system comprising:

a first blood pump configured to fluidly communicate with the patient, the first blood pump comprising;

a first pump chamber;

a first inlet valve configured to control the flow of blood to the first pump chamber;

a first outlet valve configured to control the flow of blood from the first pump chamber;

a second pump chamber;

a second inlet valve configured to control the flow of blood to the second pump chamber;

a second outlet valve configured to control the flow of blood from the second pump chamber; and

one or more diaphragms, each of the first and second pump chambers, the first and second inlet valves, and the first and second outlet valves comprising at least a portion of the one or more diaphragms;

a control base in fluid communication with the first blood pump and configured to deliver motive fluid to the first blood pump in both a first state and a second state, the control base configured to alternate between the first state and the second state such that the first blood pump delivers pulsatile blood flow to the patient; and

a second blood pump configured to fluidly communicate with the patient, the second blood pump comprising;

a first and a second pump chamber;

a first and a second inlet valve; and

a first and a second outlet valve,

wherein each of the first and second pump chambers, the first and second inlet valves, and the first and second outlet valves of the second blood pump comprises a diaphragm actuation region configured to move in response to contact with motive fluid, and wherein the first pump chamber is configured to alternately fill with blood as the second pump chamber expels blood and expel blood as the second pump chamber fills with blood.

53. The cardiopulmonary bypass system of claim 52, wherein the control base is configured to provide fluid communication between a first source of motive fluid and the first inlet valve and the second outlet valve of the first blood pump, and is configured to provide fluid communication between a second source of motive fluid and the first outlet valve and the second inlet valve of the first blood pump, when in the first state, and

wherein the control base is configured to provide fluid communication between the first source of motive fluid and the first outlet valve and the second inlet valve of the first blood pump, and is configured to provide fluid communication between the second source of motive fluid and the first inlet valve and the second outlet valve of the first blood pump, when in the second state.

54. The cardiopulmonary bypass system of claim 52, wherein the control base is configured to provide fluid communication between a first source of motive fluid and the first blood pump and between a second source of motive fluid and the first blood pump in both the first and second states, and

wherein the first source of motive fluid provides motive fluid at a first pressure level and the second source of motive fluid provides motive fluid at a second pressure level, wherein the first and second pressure levels are such that the pressure of extracorporeal blood within the system is maintained within a range of between about −

250 mmHg and about 500 mmHg in the event of an interruption of fluid communication between the first blood pump and the patient during operation of the first blood pump.

55. The cardiopulmonary bypass system of claim 52, wherein continued cycling of the first blood pump in the event of an interruption of fluid communication between the first blood pump and the patient changes the temperature of extracorporeal blood within the system by no more than about 5°

C.

56. The cardiopulmonary bypass system of claim 52, further comprising a third blood pump configured to fluidly communicate with the patient, the third blood pump comprising:

a first and a second pump chamber;

a first and a second inlet valve; and

a first and a second outlet valve,

wherein each of the first and second pump chambers, the first and second inlet valves, and the first and second outlet valves of the third blood pump comprises a diaphragm actuation region configured to move in response to contact with motive fluid, and wherein the first pump chamber is configured to alternately fill with blood as the second pump chamber expels blood and expel blood as the second pump chamber fills with blood.

57. A method of mixing medical fluid with blood for delivery to a patient, the method comprising:

providing a first pump configured to effect movement of medical fluid, the first pump comprising;

a first and a second pump chamber;

a first and a second inlet valve; and

a first and a second outlet valve,

wherein each of the first and second pump chambers, the first and second inlet valves, and the first and second outlet valves comprises a diaphragm actuation region;

providing a second pump configured to effect movement of blood, the second pump comprising;

a first and a second pump chamber;

a first and a second inlet valve; and

a first and a second outlet valve,

wherein each of the first and second pump chambers, the first and second inlet valves, and the first and second outlet valves of the second pump comprises a diaphragm actuation region;

alternately moving the diaphragm actuation regions of the first pump via motive fluid at a first pressure level and via motive fluid at a second pressure level;

alternately moving the diaphragm actuation regions of the second pump via motive fluid at a third pressure level and via motive fluid at a fourth pressure level;

obtaining information regarding one or more of the flow rate of medical fluid from the first pump and the flow rate of blood from the second pump; and

altering one or more of the flow rate of medical fluid from the first pump and the flow rate of blood from the second pump.

58. The method of claim 57, wherein the step of altering comprises adjusting one or more of the first pressure level of motive fluid, the second pressure level of motive fluid, the third pressure level of motive fluid, and the fourth pressure level of motive fluid.

59. The method of claim 57, further comprising alternately filling the first pump chamber of the first pump with medical fluid while expelling medical fluid from the second pump chamber of the first pump and expelling medical fluid from the first pump chamber of the first pump while filling the second pump chamber of the first pump with medical fluid.

60. A method of assisting the heart of a patient, the method comprising:

providing a pump comprising;

a first and a second pump chamber;

a first and a second inlet valve; and

a first and a second outlet valve,

wherein each of the first and second pump chambers, the first and second inlet valves, and the first and second outlet valves comprises a diaphragm actuation region;

cyclically altering between introducing blood into the first pump chamber while expelling blood from the second pump chamber and expelling blood from the first pump chamber while introducing blood into the second pump chamber, wherein the period over which blood is introduced into and expelled from the first chamber and over which blood is expelled from and introduced into the second pump chamber defines a pump cycle, and wherein said step of cyclically altering occurs at a rate of between about 10 cycles per minute and about 200 cycles per minute; and

actively opening the first and second inlet valves and first and second outlet valves by alternating between providing motive fluid to the first inlet valve and the second outlet valve and providing motive fluid to the first outlet valve and the second inlet valve.

61. The method of claim 60, wherein the diaphragm actuation region of the first pump chamber reaches an expelling end-of-stroke position before the end of a pump cycle and wherein the diaphragm actuation region of the second pump chamber reaches an expelling end-of-stroke position before blood is provided to the second pump chamber during the pump cycle such that the pump provides pulsatile blood flow to the patient.

62. The method of claim 61, wherein the diaphragm actuation region of the first pump chamber transitions between a filling mode and an expelling mode before reaching a filling end-of-stroke position and wherein the diaphragm actuation region of the second pump chamber fails to reach a filling end-of-stroke position during the pump cycle such that the pump provides substantially constant blood flow from the patient.

63. The method of claim 60, wherein the motive fluid is provided to the first inlet valve and the second outlet valve at a first pressure level and the motive fluid is provided to the first outlet valve and the second inlet valve at the first pressure level.

64. The method of claim 63, further comprising actively closing the first and second inlet valves and first and second outlet valves by alternating between providing motive fluid at a second pressure level to the first outlet valve and the second inlet valve and providing motive fluid at the second pressure level to the first inlet valve and the second outlet valve.

65. The method of claim 60, further comprising alternately applying a motive fluid at a first pressure to the first pump chamber to thereby draw blood into the first pump chamber while applying a motive fluid at a second pressure to the second pump chamber to thereby expel blood from the second pump chamber and applying the motive fluid at the second pressure to the first pump chamber to thereby expel blood from the first pump chamber while applying motive fluid at the first pressure to the second pump chamber to thereby draw blood into the second pump chamber.