US3495540A - Atraumatic blood pump - Google Patents

Description

3 Sheets-Sheet 1 Filed Feb. 26, 1968 N I f 3- INVENTOR.

MILES LOWELL EDWARDS a flit orney I Feb. 17,1970 M LEowARD s 4 ATRAUMATIC snoop rim? Filed Feb. 25, 1968 v w v s Sheets-Sheet s I INVENTOR.

MILES LOWELL EDWARDS United States Patent 3,495,540 ATRAUMATIC BLOOD PUMP Miles Lowell Edwards, 13191 Sandhurst Place, Santa Ana, Calif. 92705 Filed Feb. 26, 1968, Ser. No. 708,108 Int. Cl. F04b /00, 39/14, 43/08 US. Cl. 103-148 18 Claims ABSTRACT OF THE DISCLOSURE A series of resilient plastic tubes is connected in parallel between inlet and outlet manifolds with inlet and outlet check valves in said connections. The tubes are disposed between normally stationary abutment blocks and reciprocating squeezing blocks, the latter producing the pumping action. The squeezing blocks are actuated in out-of-phase relationship by an eccentric mechanism to minimize pulsations and produce substantially steady flow total discharge. By retracting the abutment blocks, the tubes and manifolds may be removed as a single harness unit for sterilizing or such unit may be made as a disposable item to be discarded after a single use.

BACKGROUND OF THE INVENTION This invention relates to liquid pumps and has particular reference to the pumping of blood from a patient as in an extra corporeal circuit through an oxygenator (artificial lung) or dialyzer (artificial kidney).

Prior art pumps are subject to a number of objections and disadvantages for such use. Some have a traumatic effect on the blood cells, some present a problem of sterilization, some produce excessive pulsations of the blood, some cannot be connected into the blood circuit and put into operation quickly and conveniently and some are objectionably complicated and expensive to manufacture.

SUMMARY OF THE INVENTION The present pump comprises a series of resilient plastic tubes connected in parallel between an inlet manifold and an outlet manifold. Inlet and outlet check valves are incorporated in said connections. There is a plurality of pairs of such tubes. The tubes of each pair are disposed on opposite sides of a reciprocating squeezing block and each tube is confined in a space between the squeezing block and an abutment block which remains stationary during operation of the pump. The pumping action in the tubes of each such pair thereby occurs in 180 phase relationship.

In a pump having two such pairs of tubes, the squeezing block between the second pair reciprocates in 90 phase relationship with the squeezing block between the first pair. Thus, the flows from the four tubes occur in 90 phase relationship as in a four cylinder piston pump where the pistons are reciprocated by crank throws displaced 90 from each other in a crankshaft. This minimizes pulsations and produces nearly steady flow total discharge from the outlet manifold.

The pumping tubes and manifolds are made as an insertable and removable harness unit which may be cleaned and sterilized apart from the pumping mechanism or discarded after a single use. The abutment blocks of each pair are retractable in opposite directions away from each other for convenient insertion and removal of the tube and manifold harness unit.

Objects of the invention are to provide an improved liquid pump for special purposes, to provide an improved blood pump, to provide a pump which has less traumatic effect on blood cells than other available blood pumps, to provide a pump of the type described which produces ice continuous and substantially steady flow, to provide a pump having easily insertable and removable disposable pumping tubes and to provide a pump of the type described which is relatively simple and inexpensive to manufacture and which is rugged and reliable and essentially trouble free in operation.

The invention will be better understood and additional objects and advantages will become apparent from the following description of the preferred embodiment illustrated in the accompanying drawings. Various changes may be made, however, in the details of construction and arrangement of parts and certain features may be used without others. All such modifications within the scope of the appended claims are included in the invention. Although the invention is described in connection with the pumping of blood, it is to be understood that the pump is of general application and may be used for other purposes.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a front elevation view, with parts broken away, showing a pump embodying the principles of the invention, the abutment blocks being in retracted position;

FIGURE 2 is a view on the line 22 in FIGURE 1;

FIGURE 3 is a view on the line 33 in FIGURE 1;

FIGURE 4 is a view on the line 44 in FIGURE 1, but showing the abutment blocks in operating position;

FIGURE 5 is a view on the line 5-5 in FIGURE 4;

FIGURE 6 is an enlarged perspective view of one of the pumping tubes;

FIGURE 7 is an enlarged cross sectional view of the tube in FIGURE 6, showing its normal shape in expanded condition;

FIGURE '8 is a view similar to FIGURE 7, showing the shape of the tube in squeezed condition;

FIGURE 9 is an enlarged view on the line 9-9 in FIGURE 1, showing an inlet valve;

FIGURE 10 is an enlarged view on the line 1010 in FIGURE 1, showing an outlet valve; and

FIGURE 11 is a view on the line 1111 in FIGURE 1, showing one of the manifold clamps.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIGURES 1 and 4, the pump mechanism is carried by a vertical base plate 10, the pump structure being mounted on the front of this base plate and the drive elements being mounted on the back. The pump mechanism comprises, essentially, four stationary but retractable abutment blocks A A A and A two Vertically extending, horizontally reciprocating squeezing blocks B and B and four vertical pumping tubes T T T and T FIGURE 1 shows the abutment blocks retracted for insertion and removal of the pumping tubes and FIGURE 4 shows the abutment blocks in operating position.

Pumping tubes T and T are inserted in spaces on opposite sides of squeezing block B between this squeezing block and the two stationary abutment blocks A and A Pumping tubes T and T are similarly inserted in spaces on opposite sides of squeezing block B between this block and stationary abutment blocks A, and A In the operation of the pump, the squeezing blocks B and B reciprocate back and forth in out-of-phase relationship between their associated abutment blocks to apply squeezing pressure successively to the four tubes.

Pumping tubes T to T are part of a removable harness unit H which includes an inlet manifold tube 11 and an outlet manifold tube 12. Tube 11 has an open end 13 for connection with a blood supply tube and tube 12 has an open end 14 for connection with a blood discharge tube. In order to make the flow paths of equal length between manifold ends 13 and 14 for all the pumping tubes T to T and to assist in bleeding air out of the tubes, the ends 13 and 14 are disposed at opposite ends of the harness unit. The entire harness unit is secured in operative position by four quick release manifold clamps 15 on a front plate 16, as shown in FIG- URE 1.

Each of the pumping tubes T to T is connected with a branch of inlet manifold tube 11 as shown in FIG- URE 9. The manifold branches have bell ends with flanges which seat against flanges 21 on the bell ends of the pumping tubes. These flanges are clamped together by an internally grooved collar 22 and the joint may be sealed by suitable adhesive, if desired. These bell end parts contain a cage 23 for an inlet ball check valve 25. The interior of cage 23 has alternate ridges 26 to hold the ball centered and grooves 27 to pass blood around the ball when it is in open position. In closed position the ball seats against a soft washer 28 which is supported on its upstream side by a hard washer 29. Ball is preferably made of stainless steel and the other parts shown in FIGURE 9 are made of suitable plastics.

The outlet check valve shown in FIGURE 10 is similarly constructed except that cage 23 and seat washers 28, 29 are reversed. The inlet valve in FIGURE 9 is shown in closed position and the outlet valve in FIGURE 10 is shown in open position.

Ball cages 23 may be omitted if desired, the ridges 26 and grooves 27 being formed in the bell end of the pumping tubes at their inlet ends (FIGURE 9) and in the bell ends of the manifold branches at the outlet ends (FIGURE 10).

The construction of pumping tubes T to T is shown in FIGURES 6 to 8 wherein the tube is designated generally as T. Each tube is moulded with a circular lumen 30 and thin walled regions 31 formed by flat surfaces on the front and back sides. The opposite lateral sides are equipped with longitudinal ridges 32 to fit in positioning grooves 33 in the abutment blocks and squeezing blocks as shown in FIGURE 4. Tube T is made of a resilient plastic having sufl icient elasticity to return its lumen to circular shape and fill the tube with blood when squeezing pressure is relaxed as shown in FIGURE 7. This is the condition of tube T in FIGURE 4.

When the tube is squeezed, the inlet valve closes as shown in FIGURE 9 and the outlet valve opens as shown in FIGURE 10 to discharge blood into outlet manifold 12. The excursion of squeezing blocks B and B is such that the opposite inside wall surfaces are never pressed against each other so as to crush the blood cells and produce excessively high flow velocities. In the maximum squeezed condition, the opposite wall surfaces remain spaced apart from each other a slight distance as shown in FIGURE 8 and also in tube T in FIGURE 4. The thin walled sections at 31 form bending lines which cause the tubes to assume this configuration when squeezed to the maximum extent.

The four clamps 15 are of identical construction as shown in FIGURE 11. The manifold tube is clamped between two members 1 and 2 which are pivotally connected together at 3. The member 1 is mounted on the plate 16. Clamping pressure is applied by a nut 4 on a bolt 5 which is pivotally mounted on a pin 6 in the member 1. The bolt is adapted to swing into a slot 7 in the member 2.

Referring now to FIGURES 4 and 5, squeezing block B is reciprocated by a cross head 34 comprising a pair of grooved blocks 35 and 36 which are clamped by screws 37 on a pair of horizontal rods 41 and 42. For properly positioning the squeezing block on the cross head, the block 35 has tongue and groove engagement with the squeezing block at 43. Block 35 is also equipped with an outstanding locator pin 44 which fits in a hole 45 in the squeezing block. The squeezing block is detachably secured to the cross head by a pair of thumb screws 46 which have threaded engagement with block 35. Thus,

the squeezing block B is readily removable for cleaning and sterilizing. The front portion of block 35 reciprocates in an opening 47 in plate 16.

Squeezing block B is detachably connected in like manner to a similar cross head 50 clamped on the two horizontal rods 51 and 52. Rods 51 and 52 are freely slidable through the cross head 34 supporting the squeezing block B and rods 41 and 42 are freely slidable through the cross head 50 supporting squeezing block B These four rods slide in the bearing blocks 55 and 56 in FIGURES 1 and 4.

Rods 41 and 42 and squeezing block B are reciprocated by a cross head 60 which is pivotally connected by a link 61 with the outer end of a rocker arm 62. Rocker arm 62 is pivotally mounted on a vertical pin 63 in a bracket 64 on the back side of plate 10. The inner end of rocker arm 62 is pivotally connected with a pitman 6-5 having a strap 66 on an eccentric 67 on a vertical drive shaft 68. Drive shaft 68 is rotated at controlled speed by a motor 70 which may be a variable speed motor or a constant speed motor with a variable speed drive.

In a similar manner the rods 51 and 52 and squeezing block B are reciprocated by a cross head 71 which is pivotally connected by link 72 with the outer end of a rocker arm 73. Rocker arm 73 i pivotally mounted on a vertical pin 74 in a bracket 75 on the rear side of plate 10. The inner end of rocker arm 73 is pivotally connected with a pitman 76 having a strap 78 on an eccentric 79 on drive shaft 68. Eccentric 79 is displaced at an angle of 90 from eccentric 67 as indicated by the angle 80 in FIGURE 4.

In the position of the parts shown in FIGURE 4, rocker arm 62 is in its limit position of clockwise rotation causing squeezing block 13 to assume its limit position in movement to the right. This squeezing block has released all pressure from pumping tube T and has squeezed tube T to its fully squeezed position wherein a small area of lumen remains to avoid crushing of the blood cells and to avoid creating excessive velocities of the blood in escaping from the flattened tube. At the same time, rocker arm 73 is in its mid position placing squeezing block B in mid position equidistant between abutment blocks A and A Thus, the pumping tubes T and T are squeezed equally at this instant although the squeezing pressure on one tube is being increased while the squeezing pressure on the other tube is being released.

Assuming clockwise rotation of shaft 68, squeezing block B, will be moving to the right producing a pumping phase in tube T and a suction phase in tube T Squeezing block B being in its extreme right-hand position, has just completed a pumping phase in tube T and a suction phase in tube T and is about to start a suction phase in tube T and a pumping phase in tube T Thus, the four pumping tubes discharge blood into outlet manifold 12 during portions of four overlapping intervals in each revolution of drive shaft 68, each complete pumping interval having a duration corresponding to 180 of rotation of the drive shaft. These pulsations correspond to the overlapping voltage pulsations resulting from half wave rectification of four phase alternating current whereby the pulsations in total flow at the outlet 14 of manifold 12 are attenuated and result in continuous, substantially steady flow without wide variations in velocity.

FIGURE 1 shows how the abutment blocks A A A and A are retracted for insertion and removal of the harness unit H comprising pumping tubes T to T and inlet and outlet manifolds 11 and 12. Referring also to FIGURE 4, abutment blocks A and A are detachably mounted on a pair 'of cross heads which are clamped on a pair of horizontal rods 91 and 92. Similarly, the abutment blocks A and A are detachably mounted on a pair of cross heads 93 which are clamped on a pair of horizontal rods 95 and 96. Cross heads 90 and 93 are similar to the cross head 34 shown in FIGURE 5 except that different pairs of rods are clamped by the different cross heads as explained above.

Rods 95 and 96 slide freely through cross heads 90 and rods 91 and 92 slide freely through cross heads 93. All four of the rods 91, 92, 95, 96 slide freely through the cross heads 50 and 34 which carry the squeezing blocks B and B All four rods are slidably supported in bearings in the two bearing blocks 55 and 56.

Rods 91 and 92 are clamped in a cross head 100 by means of screws 101 as shown in FIGURE 2 and rods 95 and 96 slide freely through this cross head. Rods 95 and 96 are clamped in a cross head 102 by means of screws 103 as shown in FIGURE 3 and rods 91 and 92 slide freely in this cross head. The two cross heads 100 and 102 are pulled toward each other by a pair of tension springs 105. A horizontal shaft 110 between the two'cross heads carries a pair of cam rollers 111 arranged to press the two cross heads away from each other under spring tension when the shaft is rotated 90 from its FIGURE 1 position. This shaft is rotatable by a handle lever 112 which may be held in its vertical broken line positlon by a spring catch 113.

In the solid line position of the parts in FIGURE 1, springs 105 pull the two cross heads 100 and 102 together and hold the four abutment blocks A to A in retracted positions for releasing the pumping tubes T to T so that the harness unit H may be removed. When handle 112 1s swung 90 clockwise in FIGURE 1 to its broken line position, the cam rollers 111 move the cross heads 100 and 102 apart to their broken line position, shifting the abutment blocks A to A in the directions of arrows 115. This places the abutment blocks in operative positions as shown in FIGURE 4 where it will be observed that handle 112 is held in vertical position by catch 113. To change the harness unit H, it is only necessary to release catch 113 and the four manifold clamps 15.

Other fluid circuit arrangements are also possible. By omitting the manifold tubes 11 and 12, the pumping tubes T to T may be connected into four separate pumping circuits if desired. Or, two of the pumping tubes may be connected to a first pair of inlet and outlet manifold tubes and the other two pumping tubes connected to a second pair of inlet and outlet manifold tubes to pro vide two separate pumping circuits.

Having now described my invention and in what manner the same may be used, what I claim as new and desire to protect by Letters Patent is:

1. A pump comprising a pair of abutment block, a pair of resilient pumping tubes between said abutment blocks, a squeezing block mounted for reciprocation between said pumping tubes, and quick release means to retract said abutment blocks simultaneously away from said pumping tubes for insertion and removal of said tubes.

2. A pump as defined in claim 1, said blocks having open spaces there'between on one side of said tubes for lateral insertion and removal of the tubes.

3. A pump as defined in claim 1, said blocks having longitudinal tube positioning grooves and said tubes having longitudinal ridges disposed in said grooves.

4. A pump as defined in claim 1, said tubes being connected at their opposite ends with inlet and outlet manifold tubes, said assemblage of tubes forming a removable harness unit.

5. A pump as defined in claim 4, said pumping tubes being disposed in vertical positions, said inlet manifold tube being connected with the lower ends of said pumping tubes and said outlet manifold tube being connected with the upper ends of said pumping tubes.

6. A pump as defined in claim 4 including check valves in said tube connections.

7. A pump comprising a first pair of abutment blocks, a first squeezing block mounted for reciprocation between said abutment blocks, there being spaces between opposite sides of said squeezing block and said abutment blocks for a first pair of resilient pumping tubes; a second pair of abutment blocks, a second squeezing block mounted for reciprocation between said second pair of abutment blocks, there being spaces between opposite sides of said second squeezing block and said second abutment blocks for a second pair of resilient pumping tubes; and means for reciprocating said squeezing blocks in out-of-phase relationship.

8. A pump as defined in claim 7, said reciprocating means comprising a drive shaft having a pair of eccentrics driving said squeezing blocks, said eccentrics being disposed in angular relationship.

9. A pump as defined in claim 7, said squeezing blocks being mounted on a pair of sliding cross heads.

10. A pump as defined in claim 7, including means for retracting said abutment blocks for inserting pumping tubes into said spaces and for removing said pumping tubes from said spaces.

11. A pump as defined in claim 10, said abutment blocks being mounted on sliding cross heads, said retracting means comprising a handle arranged to move said cross heads between operating and retracted positions.

12. A pump as defined in claim 7, including a plurality of pairs of parallel rods mounted for longitudinal sliding movement, said first squeezing block being connected with a first pair of said rods, said second squeezing block being connected with a second pair of said rods, means for reciprocating said first and second pairs of rods, a third pair of said rods connected with an abutment block of said first pair of abutment blocks and connected with an abutment block of said second pair of abutment blocks, a fourth pair of said rods connected with the remaining abutment blocks, and means for sliding said third and fourth pairs of rods in opposite directions to move said abutment blocks' between operating and retracted positions.

13. A removable harness unit for a pump comprising a plurality of resilient pumping tubes adapted to be squeezed for pumping a liquid through the tubes, an inlet manifold tube connected at intervals therealong with one end of each of said pumping tubes, said manifold tube having an inlet end at one end of said unit, inlet check valves in said connections, an outlet manifold tube connected at intervals therealong with the opposite ends of said pumping tubes, and outlet check valves in said last connections, said outlet manifold tube having a discharge end at the opposite end of said unit so that the flow paths through said pumping tubes are of equal length between said inlet and discharge ends of said manifold tubes.

14. A pumping tu-be comprising a tube of resilient material having a circular lumen, a pair of longitudinal ridges on opposite sides of said tube, said tube having a pair of external flat sides forming thin Wall sections on its opposite sides between said ridges to provide bending lines when the tube is flattened, and flanged bell ends on said tube forming housings for check valves.

15. A pump comprising a pair of abutment blocks, a pair of resilient pumping tubes, one of said tubes engaging one of said abutment blocks and the other tube engaging the other abutment block, reciprocating squeezing means arranged to squeeze said two tubes against the respective abutment blocks, and quick release means arranged to retract said two abutment blocks simultaneously in opposite directions away from both tubes for removal and insertion of said tubes.

16. A pump as defined in claim 15, said blocks and squeezing means having open spaces therebetween on one side of said tubes for lateral removal and insertion of the tubes.

-17. A pump as defined in claim 15, said squeezing means squeezing said two tubes alternately.

18. A pump as defined in claim 15, said tubes, abutment blocks and squeezing means being disposed in a common plane, said squeezing means reciprocating in said plane, and said abutment blocks having retractive movements in said plane for said quick release.

References Cited UNITED STATES PATENTS 8 2,925,045 2/1960 Mascaro 103-149 3,045, 01 7/1962 Rippingille 103 14s 3,403,631 10/1968 Tangernan 103 149 FOREIGN PATENTS 350,547 1/1961 Switzerland.

DONLEY J. STOCKING, Primary Examiner WILBUR .T. GOODLIN, Assistant Examiner

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