Blood Pump

Abstract

This invention relates to a pump for an "artificial kidney machine", or hemodialysis device; and primarily is designed for the pumping of blood for purification in such a system using the recently announced procedure of "single needle" dialysis, whereby a single needle is temporarily inserted into a vein or artery of a patient through which blood is withdrawn from the vein for purification and returned to the patient through the same needle. Such a dialysis system requires, in addition to the filter and pump, a device commonly called an "occluder" by means of which purified blood from the filter is prevented from flowing to the needle during the suction stroke of the pump when blood is withdrawn from the patient and is open to flow during the pumping stroke.

Description

BACKGROUND OF THE INVENTION

One of the important medical advances of our time is the invention and development of the "artificial kidney machine" referred to in medical circles as a "hemodialysis machine," by Dr. Willem Kolff, now associated with the University of Utah. The dialysis machine was invented by Dr. Kolff about 25 years ago. While a modern hemodialysis system for purifying blood is often categorized as "an artificial kidney machine," it is in fact an assemblage of specialized laboratory or clinical apparatus which can be made to filter out waste material normally processed by the kidneys and expelled from the body through the urine. Such a system generally comprises:

A. A MEANS FOR CONDUCTING WASTE LADEN BLOOD FROM THE PATIENT AND THE PURIFIED BLOOD BACK TO THE PATIENT;

B. A FILTER HAVING A MEMBRANE THROUGH WHICH WILL PASS WASTE SOLUTES WHILE PREVENTING THE PASSAGE OF BLOOD, AND THEREBY SEPARATE THE WASTE FLUIDS FROM THE BLOOD;

C. A DIALYSATE FLUID WHICH ACTS THROUGH THE MEMBRANE OF THE FILTER IN ORDER TO WITHDRAW THE FLUID WASTES IN THE BLOOD FROM THE BLOOD;

D. A DIALYSATE PROPORTIONING AND DELIVERY SYSTEM;

E. means for propelling the blood through the filter and the associated apparatus, i.e., a specialized blood pump. Preferably the pump should exert a pressure greater than that supplied by the body so as to force the purified blood back into the body and permit the withdrawal of waste laden blood from the body;

F. A HEPARIN PUMP WHICH INJECTS A MINUTE QUANTITY OF ANTI-COAGULANT INTO THE BLOOD BEING PURIFIED TO CONTROL THE BLOOD CLOTTING WHICH WOULD OTHERWISE OCCUR;

G. MUCH MISCELLANEOUS HARDWARE SUCH AS BUBBLE TRAPS, MEDICINE INJECTION CUFFS, METERING DEVICES, HEATERS AND CONTROLS FOR MAINTAINING THE DIALYSATE AND BLOOD WITHIN CLINICAL LIMITS, MONITORING DEVICES TO SOUND AN ALARM AND/OR CONTROL THE PROCEDURE SO AS TO PROTECT THE PATIENT, AND THE INSTRUMENTS NORMALLY USED BY A DOCTOR IN SUCH A PROCEDURE.

This invention is concerned with item (e), the specialized blood pump which performs an auxiliary heart function for a prolonged period, and preferably does so with minimal damage to the blood.

Since the original invention, much time and effort has been spent in trying to improve the operation of these devices in order to make them more efficient, to make the complete system truly portable and less expensive, and to develop one that could be used in the home rather than requiring treatment in a hospital or clinic. One of the defects of prior machines has been the fact that they have been very large, very expensive and required expert medical attention under clinical or surgical conditions. This made treatment not only expensive, but also required the patient to go to a hospital or clinic every two or three days for treatment - which automatically limited patients to an urban area and to those who could spend considerable time in travel to and from the hospital or clinic. Thus, most patients were financially unable to get treatment because such machines could be supplied only by large hospitals or well-endowed clinics. Many people just don't have the time or resources necessary for such a procedure. In the past, for dialysis treatment, a patient had to undergo a surgical procedure by means of which an artificial "plug-in" connection, or "canula," was placed in the artery and also in a vein, blood being withdrawn from the artery for treatment in the machine and then returned to the vein. Since there are relatively few spots in the body where an artery is close to the skin, the number of places where such a canula could be placed in an artery was very limited. The life of such a canula is quite short, as the natural bodily processes make it unuseable (a period sometimes as short as 6 weeks and seldom as long as a year) and a new, costly and painful surgical procedure was required. Eventually there is no place left to place such a canula, and the patient is doomed.

In 1971 the researchers under the direction of Dr. Kolff developed a new technique called the "single needle dialysis technique" whereby the canula problems are eliminated. In this procedure a single needle is inserted into a vein (many of which are quite close to the skin and therefore readily accessible, for withdrawing blood samples, taking blood for a transfusion or storage in a blood bank, etc.) and after this blood is purified in the machine, it is injected into the patient through the same needle. Dr. Kolff, at the University of Utah, has very recently announced a truly inexpensive dialysis machine which would be within the price range of most American families and, which is more important, could be utilized in the home. Such a system requires that a very small amount of blood be withdrawn through any suction stroke in order to avoid collapsing the vein. The volume of each stroke is usually within the range of 1.5 to 2.5 cc. per stroke at the rate of between 60 and 120 strokes per minute, depending upon the age, size of the patient, and size of the available vein. During the suction stroke of the pump, the blood is taken from the body of the patient through the single needle and one leg of a Y-connection; and then during the pumping stroke, passes through the filter and back into the patient's body through the other leg of the Y-connection and through the same needle. Patients can be readily trained to insert the needle themselves.

Such a system requires the use of at least one valve device, or occluder, which preferably is located in the tube delivering purified blood to the patient, and is operative to shut off the flow of purified blood to the patient during the suction stroke of the pump. Furthermore, this occluder, as it is commonly called, must operate in timed sequence to the operation of the pump. Obviously, the occluder must be open for the passage of blood during the time that the pump is pushing blood through the filter and back into the body of a patient, but should completely close the purified blood delivery line during that portion of the cycle in which the pump is withdrawing blood from the body of a patient.

One of the features of the present invention is that the volume of blood pumped in each stroke is variable through a wide range and adjustments can be made easily and accurately while the pump is in operation. Another feature is that the force applied to the blood in the conduit is also variable over a considerable range, and again adjustments can be made while the pump is in operation. More important is the fact that the pump and occluder of the present invention are isolated from the tubes carrying the blood from the patient to the dialysis filter and returning it to the body, so that neither the pump nor the occluder need to be sterilized between uses. It will be understood that in such a procedure as dialysis, the needle, the blood tubes, and the filter will have to be sterilized or replaced between each use, and this is commonly done; but it is unnecessary to sterilize either the pump or the occluder of the present invention, as the sterilized tubes are inserted through the pump and occluder and the blood does not come into direct contact with these devices.

OBJECTS

It is a primary object of the present invention to provide a small, light-weight pump for a dialysis machine.

It is a further object of the present invention to provide a small, light-weight pump which can be operated by hydraulic pressure that does not need to be as great as that ordinarily supplied in a city water supply, and in fact can be operated from a portable hydraulic supply, such as those found in many recreational vehicles.

It is a further object of the present invention to provide an artificial kidney pump with an infinitely variable volumetric adjustment.

It is another object of the present invention to provide a pump for a dialysis machine that is adapted to be used with a single needle dialysis system, i.e., one in which a single needle is used to withdraw blood from, and return it to the patient.

It is still another object of the present invention to provide a quiet and positive operation for an occluding device which controls the flow of the patient's blood from, and the delivery of the purified blood back to, the patient through a single hypodermic needle.

It is a further object of the present invention to provide a surgical pump, which may include an occluder, that does not have to be sterilized, since only the tubes through which the blood passes and the filter needs to be sterile since the tube or tubes may be readily inserted through the above-mentioned devices.

A still further object of the present invention is to provide a blood pump which may be used for prolonged periods of time without causing blood cell rupture known as "hemolysis."

These and other objects of the present invention will be apparent from the specification which follows taken in conjunction with the accompanying drawings in which:

FIG. 1 is a diagrammatic view of the dialysis system with which the present invention is designed to be associated, showing the pump of the present invention interposed between the supply tube to the dialysis filter for withdrawing blood from the patient and passing it to the filter.

FIG. 2 is a cross-sectional view through one of the valves of the pump, such as taken along the plane indicated by the line 2--2 of FIG. 1.

FIG. 3 is a cross-sectional view of the power section of the present invention showing also the means for supplying hydraulic power and releasing it.

FIG. 4 is a diagrammatic cross-sectional view of the pump of the present invention showing the various hydraulic supply valves in the positions they would occupy at the start of the suction phase of a cycle of operation during which blood is to be withdrawn from the body of a patient.

FIG. 5 is a timing diagram showing the operation of the three important valves and the supply of hydraulic fluid to the pressure chamber.

The single needle dialysis system with which the pump of the present invention is particularly adapted to control is shown in FIG. 1. The usual surgical hypodermic needle 10 can be inserted into any suitable vein of the patient. A Y-member 11 is affixed to the needle 10, and a suction hose 12 leads from one leg of the Y-member 11 to and through the pump 40, the section of the suction tube 12 leading from the pump to a dialysis filter 15 being indicated by the reference character 14. It will be understood that the tube 12 and 14 is integral, the two reference characters being used to indicate the two sections of a single tube. The other leg of the Y-member 11 is connected to the delivery tube 13 leading from the filter 15.

It is conventional in an apparatus of this kind to pass blood through the filter 15 in two or more diverging and converging streams, and accordingly the section 14 of the tube 12 is provided with a Y-member 16 which divides the blood flowing therethrough into two tubes 14-a and 14-b. Similarly, the blood discharged from the filter passes through discharge tubes 13-a and 13-b to a common Y-member 17 and thence to a bubble trap 18. Since the filter 15 and bubble trap 18 are of known construction, it is believed unnecessary to refer further to them. It can also be noted that it is conventional practice to inject a very minute amount (usually in the order of 1.5 milliliters per hour) of heparin (an anti-coagulant) into the suction tube 12 as by means of a heparin pump 21 operated from a source of power 22, the heparin passing through tube 23 to a suitable T-connection 24 in the suction tube 22. It is customary in this art to form the tubes 12, 14, 14-a, 14-b, 13-a, 13-b and 13 of surgical plastic tubing, as such tubing under treatment conditions does not cause blood to coagulate, and is quite flexible while being of sufficient strength to withstand any pressure to which it need be subjected. Such tubing also can be readily sterilized, packed in sealed containers and sold quite inexpensively.

The single needle technique above-mentioned requires the use of an occluder which is operative to prevent flow of blood from the dialysis filter to the patient during the period of time that the pump 40 is in its suction phase and is withdrawing blood from the patient. In FIG. 1 the occluder 19 is shown associated with the delivery tube 13. In that situation, the occluder 19 is timed to close the delivery tube 13 to the flow of blood during the suction portion of a pumping cycle and is open to permit the flow of blood during the pumping phase of that cycle. It will be obvious, however, that the occluder 19 could be placed in the suction tube 12, in which event it would have to operate in exact time with the pump, so that the tube 12 would be open to the passage of blood during the time that the pump was in its suction phase and closed to the passage of blood during the pumping phase of pump 40, which is the reverse of the preferred form shown in FIG. 1.

PUMP

The pump 40 of the present invention will be contained in any suitable casing which, preferably, can be constructed of three sections: a pressure, or operating, section 41; a section 42 containing the passages for supply of hydraulic fluid under pressure, and 43 a simple casing for enclosing the control solenoids to be hereafter mentioned. Preferably, casing sections 41 and 42 are formed of some readily extrudable material, such as aluminum or some forms of plastic, so that longitudinal passageways can be formed therein and thereby avoid the expensive drilling operation required when such passageways are drilled longitudinally through the casing.

The power, or operating, section 41 is provided with a longitudinal bore 44 for the blood tube 12 and a parallel bore 45, the two communicating throughout their length, as shown in FIGS. 2 and 3. The bore 44 is somewhat larger than the tube 12, preferably as much as one-quarter or three-eighths of an inch larger in diameter than the tube 12. The parallel bore 45 is partially contained within the casing 41 and thereby provides an open slot, not identified, throughout the length of the casing block 41. This bore is adapted to permit the ready insertion of the blood tube 12 and its encompassing rubber tube 50 from the outside without the necessity of threading the tube therethrough. The bore 45 is also adapted to receive a locking member 46 provided with a suitable handle 47 so that the member 46 can readily be inserted into or removed from the bore 45. The locking member 46, when positioned in the bore 45, holds the blood tube 12 and its encompassing rubber tube 50 within the block 41 and also provides an anvil against which the tubes 12 and 50 can be pressed during operation of the pump, whereby the tubes can be completely compressed by a hydraulic pressure tube 56 described below. The alternate contraction and relaxation of the tubes 12, 50 forces blood from the pump 40 and suction of blood thereinto.

The central, or supply, section 42 of the casing is provided with two longitudinal bores: a tube 48 for supplying hydraulic fluid under pressure, and a drain 49.

The casing members 41 and 42 will have auxiliary passageways drilled therein, as will be described more in detail hereafter. It will readily be understood that the three sections of the casing 41, 42 and 43 can be rigidly attached one to another by any suitable means, such as by means of bolts, not shown, cementing, or other suitable procedure.

As mentioned before, the blood tube 12 is, throughout its length adapted to be inserted in the pump 40, encompassed within a larger tube 50. Preferably, the tube 50 is formed of soft but strong rubber and is of sufficient thickness to rather strongly resist collapsing and has such resiliency that once pressure is released it will resume its natural round shape with a force sufficiently strong and rapid to create a negative, or suction pressure. Preferably, the two tubes are cemented together so that they must act as one, particularly when pressure is released from against the tubes and the tube 50 resumes its normal round shape shown in both FIGS. 2 and 3.

Throughout the major portion of the length of the tubes 12 and 50 within the casing 41, an enlargement 55 is milled into the casing adjacent the bore 44. This can readily be done by a milling machine operating through the sides of the two bores 44 and 45 (see FIG. 3). Within the enlarged bore 55 is placed a hydraulic pressure tube 56 which is sealed at its lower end as shown in FIG. 4. The tube 56 communicates with conduit 57 and thence to the hydraulic pressure supply conduit 48 and the drain 49 through a two-position, two-way flow valve 59, as will be described hereafter. It should be noted at this point that in FIG. 3 the tube 56 is shown in its relaxed position in which it communicates with the drain 49 and hence the resilient force of the tube 50 forces the tube 56 to the semi-collapsed position shown and expels pressure fluid therefrom, FIG. 3 showing the relations of the parts during the suction phase of a cycle of pump operation. It will be understood, however, that when hydraulic fluid under pressure is admitted into tube 56 it will assume a round shape throughout its length, thereby forcibly displacing the tube 50 and its enclosed blood supply tube 12 to a semi-collapsed position (the discharge valve 86 then being open) and forcing blood through tube 12, 14 to the filter 15.

As shown in FIGS. 3 and 4, the conduit 57 communicates with the pressure supply line 48 through a branch conduit 58 and a two-position, two-way flow valve 59 (shown in these figures as being in the drain position). For purposes of exemplification only, the valve 59 is shown as having a diametric bore 60 and a radial, or T-shaped, bore 61 extending from the periphery of the valve member to the bore 60. In the position shown in FIGS. 3 and 4, conduit 57 communicates with an auxiliary drain 62 which, in turn, communicates with the drain 49, the bore 61 in the valve member 59 communicating with conduit 57 and bore 60 communicating with conduit 62. If the valve member 59 is activated (rocked in the exemplification shown) through an angle of 90.degree. (clockwise in this figure), then conduit 58 will communicate with conduit 57 through bore 60 and the conduit 61 will be blocked by registering with the interior wall of the valve casing. In the latter condition, fluid under pressure from conduit 48 will pass through conduit 58, bore 60, conduit 57, into tube 56 and compress the blood tubes 50 and 12. However, in the position shown in FIG. 3, the resiliency of the outer tube 50 tending to resume its round shape will collapse the tube 56, forcing the immediate discharge of the fluid in pressure tube 56 through conduit 61 and into drain 62. The inherent resilient force in the tube 50 acts with such strength and with such speed that it not only collapses tube 56 to permit blood to enter tube 12, but it does so with some negative pressure to suck blood from the patient into the pump.

The activation of the valve 59 is readily secured by operation of a small solenoid 115, as will now be described. The solenoid 115 is mounted in the casing section 43 and comprises the usual winding 116 and armature 117. In the exemplification shown, the armature 117 normally lies in the position shown in FIG. 3 whereby its link 118 rocks the valve member 59 90.degree. counter-clockwise so that the bores 61, 60 register with ducts 56 and 62, respectively. Upon energization of the solenoid, the solenoid armature 117 moves to the right, rocking valve member 90.degree. clockwise so that bore 60 registers with ducts 58 and 57 and liquid under pressure is allowed to enter the pressure tube 56, whereby it will compress the blood tube 12, 50. The solenoid is supplied with power through suitable leads 119 from a circuit in a timer 120 (FIG. 1) of conventional construction. The timing of the device will be described in a subsequent section. It will be understood that instead of valves 59 and 101 being rotary as shown, one can use any two-way, two-position valve, such as the straight line valves known in this art.

In connection with all dialysis techniques, it is necessary to know the volume of blood being pumped per minute. Since the volume of pressure fluid entering and leaving tube 56 is a measure of the throughput of blood through tube 12, the amount of blood pumped can readily be measured by measuring the output from the tube 56. Normal procedure is to collect this throughput for six seconds and multiply it by "10." This can readily be accomplished in the present invention by means of a graduate 70 (FIG. 4) provided with suitable indicia for volumetric measurement thereon. Such a graduate 70 communicates with the drain line 62 by means of a bypass conduit 71 which communicates with drain 62 by means of a two-position, two-way flow valve 72. The valve member includes a diametric bore 73 and a perpendicular radial bore 74 communicating with the periphery of the valve member and the diametric bore 73. Normally, the valve is in the position shown in FIG. 4 in which drain 62 communicates through a primary drain tube 75 that communicates with the main drain 40 through the bore 73. However, if the valve member is rocked counter-clockwise through an angle of 90.degree., then drain 62 communicates with the radial bore 74, one-half of drain 73 and the flow passes into conduit 71 and graduate 70. This valve can be operated by any suitable means, such as the pushbutton 76 shown in FIGS. 1 and 3. The valve will be held in the position to pass flow into the graduate 70 for a period of six seconds and then returned to its normal position. A glance at the graduate 70 will show the amount of volume of liquid contained therein, and this if multiplied by "10," gives the flow per minute. A tiny bleed drain 77 preferably is provided between the graduate 70 and the main drain 49. This permits the liquid in the drain to slowly drain therefrom so that it will be empty for again registering the amount of flow whenever it is desired to do so. It will be understood, of course, that when the graduate 70 is empty, the conduit 71 will be full of liquid as it cannot drain from the system.

VALVE CONSTRUCTION

It is obvious to those skilled in the art that a pump such as that herein described requires two valves: an inlet valve 85 and an outlet valve 86. When the pump of the present invention is utilized for single needle dialysis, a third valve is required in the occluder. Since in the preferred construction all three valves are identical in construction, only one will be described in detail, and for this purpose the outlet valve shown in FIGS. 2 and 4 will be used for exemplification. The various valves, such as outlet valve 86 shown in FIG. 2, comprise a piston 87 operating within elongated cylinder 88. The piston 87 is provided with an elongated nipple 89 which, in the retracted position of the cylinder 87 (shown in FIG. 2) registers with the outer surface of the outer tube 50, and in the projected, or operative, position so deforms the tubes 50 and 12 that they are completely closed to the flow of blood therethrough. It should be noted at this point that both FIGS. 2 and 4 show the position of the parts at the start of the valve-closing operation, and that FIG. 4 shows in dotted line its fully projected, or closed, position. Preferably, the piston 87 is provided with a peripheral depression 90 in which is seated an O-ring or other piston ring to prevent leakage of fluid past the piston.

The piston is operated by hydraulic pressure through a two-position, two-way flow valve 101 which, for purposes of exemplification, is shown as including a diametrical bore 102 and a perpendicular T-bore 103. In the closing position shown in FIGS. 2 and 4, the diametrical bore 102 registers with a short auxiliary inlet 104 which communicates with the power supply conduit 48, and with a short conduit 105 that leads to the cylinder. In the valve open position in which the piston 87 is retracted to permit flow of blood through tube 12, duct 105 registers with T-duct 103, part of duct 102, which then registers within duct 106 that leads to drain 49. This draining position is secured by rotating a valve counter-clockwise through an angle of 90.degree.. The rocking of the valve member 101 counter-clockwise from the position shown in FIGS. 2 and 4, is preferably secured by the operation of a solenoid 115, such as was described in connection with valve 59 above.

The inlet valve 85 is of the same construction as valve 86 just described, its cylinder 87-a being supplied with fluid under pressure by branch ducts 125 and 126, flow through the system being controlled by a two-position two-way flow valve 127. The valve 127 also registers with an auxiliary drain duct 128 which communicates with the main drain 49. The valve is operated by a solenoid 115 and in the same manner as that described above.

Preferably, the occluder 19 is a valve similar in all respects to those heretofore described, except that it is located near the Y-member 11 and needle 10. It can be supplied with fluid under pressure from the supply line 48 by means of a branch duct 135 (FIG. 4), a valve 136, and a tube 137 which leads from the casing of the pump 40 to the occluder 19. It should be noted, however, that the valve 136 operates out of phase with valve 127 and in phase with valve 101, as shown in FIG. 4. In fact, it would be possible to connect tube 137 to supply duct 105 leading from valve 101 to cylinder 88, but it is believed that the use of a separate valve 136 will be more readily understood. That is, the valve 136 is open to the flow of fluid under pressure to apply pressure to the occluder valve from conduit 137 simultaneously with the operation of valve 101 to supply fluid under pressure to the cylinder 87, at which time valve 127 is positioned to permit the flow of water from its cylinder 87 to drain 128, 48. It should also be noted that when the valve 136 is rocked counter-clockwise from the position shown in FIG. 4, fluid can pass from tube 137 to the drain duct 138 which connects to drain 128 and thence to main drain 49.

It will be understood that a preferred liquid fluid for operating the various valves and the pressure tube 56 will be water from a residential or hospital supply, such as that provided by water line 145. Since most water supplies have greater pressure than is needed or desired for operation of the pump of the present invention, it is expected that a pressure regulating valve 146 will be interposed between the water line 145 and the pump supply line 48. It is expected that water will normally be used in the operation of the pump of the present invention, as it is not only relatively cheap, but is available in practically all homes and all hospitals.

TIMING

As indicated above, the various valves and the pressure tube 56 are operated through their respective two-way flow control valves 127, 101, 136 and 59. These valves are operated by electric power through a sequence timer 120. The timer is supplied with power through any suitable electrical conduit 121 which can be connected to any suitable power supply. The timing sequence is so set that the respective solenoids are operative to open the outlet and occluder two-way control valves 101 and 136 to drain and to position inlet valve 127 and pressure chamber valve 59 to conduct enough water under pressure to chamber 87-a and tube 56, respectively. Conversely, the pressure chamber and inlet flow valves 59 and 127 are positioned to conduct water from the pressure tube 56 and inlet valve cylinder 87-a to drain substantially simultaneously with positioning the outlet and occluder valves 101 and 136 to conduct water under pressure from power supply duct 48 to their respective valves. This timing is shown in FIG. 5 and in the table below. It can be noted that the inlet valve 127 starts to close shortly before outlet and occluder valves 101 and 136 are opened to drain and before pressure tube 56 comes to position of equilibrium between suction and pressure.

The timing chart shown in FIG. 5 is shown to include a single cycle of operation beginning with the start of positioning outlet and occluder valves 101 and 136 to conduct water under pressure to their respective valve-operating devices, which is the beginning of the suction phase of a pump cycle. At this moment inlet valve 127 is being positioned to conduct water to drain, as is valve 59, which permits the flow of water from pressure tube 56 to drain. At this time the resilient strength of the outer tube 50 rapidly forces the tube 56 to the partially closed position shown in FIG. 3 and creates a suction on the blood supply line 12. At the end of this phase the valves reverse their position and valves 101 and 136 are opened to drain and valves 127 and 159 are positioned to conduct pressure fluid to their respective chambers.

This can perhaps better be explained by a table showing the valve conditions in which the phase "open to pressure" is used to indicate that the diametrical bore of the respective valves is positioned to conduct water under pressure from main supply duct 48 to the respective chambers and the phrase "open to drain" is used to indicate that the valve is positioned to pass water from the respective chamber to drain: ##SPC1##

It will be understood that it is conventional to provide means for adjusting the length of the various phases of a timing cycle so that the number of strokes per minute and the amount of blood per cycle can be changed at the discretion of the operator. Since this is a conventional feature of many timers, it is not deemed necessary to explain it herein.

It is believed that the hereinbefore stated and other advantages of the pump of the present invention will be obvious to those skilled in the art. It is also obvious that the pump of the present invention can be used in connection with other organs, excised organs in banks, for open heart and heart transplant surgery, and the like. Accordingly, it is intended that all modifications which lie within the scope of the underlying inventive concepts are to be included within the scope of the claims and that the invention is not to be limited to the particular forms herein shown and described.

Claims

1. A surgical pump comprising:

1. a casing;

2. a longitudinal duct through said casing adapted to receive a blood tube;

3. an inlet valve member in said casing adjacent one end of said duct and an outlet valve member in said casing adjacent the other end of said duct each of said valves comprising:

a. a cylinder within said casing,

b. a piston operating in said cylinder, said piston having a projection engaging said blood tube; and

c. means for alternately supplying fluid under pressure to and draining fluid from said cylinder;

4. a pressure tube within said duct and lying adjacent said blood tube;

5. means for supplying fluid under pressure to said pressure tube substantially simultaneously with the opening of said outlet valve and the closing of said inlet valve and for draining said pressure tube and substantially simultaneously opening said inlet valve and closing said outlet valve; and

6. resilient tube adapted to lie in said duct and leading into a discharge

2. The apparatus of claim 1 comprising also an occluder in the discharge line of said pump and means for operating said occluder to open said discharge line to flow simultaneously with the opening of the outlet valve to flow and closing the occluder to flow simultaneously with the closing

3. The apparatus of claim 1 comprising also means for measuring the flow

4. A dialysis pumping system for use in connection with a single needle dialysis technique in a kidney machine in which blood is taken from a patient and returned to the patient after treatment through a single needle, said pumping system comprising:

1. a casing,

2. a longitudinal duct through said casing, said duct being adapted to receive a flexible blood tube,

3. a power supply conduit in said casing for supplying fluid under pressure,

4. a drain conduit in said casing for draining fluid,

5. an inlet valve at one end of said longitudinal duct and a discharge valve at the other end of said duct, said valves comprising:

a. cylinders in said casing communicating with said duct, and

b. pistons within said cylinders, said pistons having projections bearing against said blood tube,

6. an enlarged chamber adjacent to, and communicating with, said duct between said inlet valve and said outlet valve,

7. a resilient pressure tube in said enlarged chamber,

8. branch conduits leading from said power supply conduit to said inlet valve cylinder, said pressure tube and said discharge valve cylinder,

9. branch conduits leading from said inlet valve cylinder, said pressure tube and said discharge valve cylinder to said drain conduit,

10. flow valves in said branch conduits,

11. means for operating said flow valves,

12. a timer for operating said last mentioned means in sequence to connect said inlet valve and said pressure tube to said pressure supply conduit and close them to drain and simultaneously opening said discharge valve to drain and closing it to the pressure supply conduit; and alternately open the inlet valve and the pressure tube to drain while closing them to the pressure conduit and simultaneously opening the discharge valve to the pressure conduit while closing it to drain;

13. means for operating an occluder valve simultaneously and in parallel phases with said discharge valve; and

14. a blood tube adapted to lie in said duct and having a strongly resilient tube encompassing and cemented to the portion of said blood tube adapted to lie within said duct, whereby a vacuum will be applied to said

5. The pumping system of claim 4 wherein the inlet and discharge valves are operated by water pressure which is controlled by respective solenoids.