US2625932A - Blood transfer apparatus - Google Patents

Description

Jan. 20, 1953 P. F. SALISBURY BLOOD TRANSFER APPARATUS Filed Ja n. 10, 1949 5 Sheets-Sheet 1 Jan. 20, 1953 P. F. SALISBURY BLOOD TRANSFER APPARATUS 3 Sheets-Sheet 2 Filed Jan. 10, 1949 4 x G\ n a 2 m 3 A? M 6 6 a Q a Z =7 1 M9 2% 21 w l 22 INVENTOR.

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Patented Jan. 20, 1953 Peter F. Salisbury, Los Angeles, Calif. Application January 10, 1949, Serial No. 70,013

This invention relates to blood transfer. It

deals particularly with that branch of the medical art in which all or a large part of the blood supplies of two persons are interchanged.

Y The basic object of the invention is to provide a method and apparatus for effecting and for metering the interchange of blood between a.

patient and a donor in a manner to equalize the flow in each direction. Another object is to provide a blood transfer apparatus having primary means for approximately metering the flow of blood in both directions and having additional means for correcting any errors in measurement occurring in the operation of the primary metering means. I

A further object of the invention is to provide an improved blood transfer mechanism including an improved intravenous catheter having means for protecting its inlet against being closed by an occluding membrane.

Another object is to provide a blood transfer apparatus having an improved means for eliminating gas bubbles from the blood being transierred. Y

Another object is to provide a blood transfer apparatus having improved pumping mechanism that will have a positive pumping action Without injuring a significant number of the blood cells.

Another object is to provide a blood metering apparatus of a highdegree of accuracy. In this connection my invention deals with a problem that has been adiiiicult one for medical'science for many years past. Although numerous proposals for a blood metering apparatus have been made in the past, none have as yet been sufiiciently accurate in their metering function to be completely satisfactory. I believe that my invention meets the strictest requirement for accuracy in metering.

Other objects will become apparent in the ensuing specifications and appended drawings in which;

Fig. 1 is a schematic view of an apparatus embodying my invention.

Fig. 2 is a detail sectional view of the improved metering unit of my invention.

Fig. 3 is a detail sectional view of the improved catheter of my invention.

Fig. 4 is aperspective view of the catheter.

Fig. 5 is a detail sectional view of the bubble trap of my invention.

Fig. 6 is a plan view partially in section of a multiple valve unit which may form a part of the apparatus of my invention.

Fig. 7 is a sectional view of the same taken on the line l'l of Fig. 6. 1 i

Fig. 8 is a front View partially in section of the improved pump apparatus of my invention.

9 is a transverse sectional view of the pump apparatus taken on the line 9-9 ofFig. 8.

13 Claims. (Cl. 128214) Fig. 10 is a detail sectional view of a portion of the pump taken on the line l0l0 of Fig. 8.

Fig. 11 is a schematic diagram of an apparatus embodying a modified form of my invention.

Referring now to the drawings in detail, I have represented schematically in Fig. 1, purely as an illustration of one possible embodiment of the invention, the

Arrangement of apparatus in general A and B represent two human bodies between which the blood is being interchanged. Into a vein of each of these bodies is inserted a double lumen catheter C having a withdrawal channel I 0 and. an injection channel I I. Blood is pumped from the withdrawal channel it) by pumps P and P into metering units M and N. Each of the metering units M, N comprises a cylinder i2 and a floating piston 13 defining with the respective ends thereof chambers I4, l5, It and I1 respectively. From the pumps P, P a series of,

valve controlled delivery tubes l8, I9, 20 and 2| lead through connections 22, 23, 24 and 25 to the cylinders I2 of the respective metering units M and N, and from the connections 22, 23, 24 and 25, a series of return lines, also valve controlled, lead back to the injection channels. These return lines are indicated at 26, 21, 28 and 29 respectively. The return lines 26 and 2B are joined to the injection channel of body A by a common connection 30 and the return lines 21 and 29 are joined to the injection channel of body B by a common connection 3!.

I contemplate employing plastic tubing for the delivery lines I8-2I andfor the return lines 26-29. In such event, there will preferably be an individual valve for each of these tubes, as described in detail hereinafter, and the valves will be of the type embodying clamping jaws for constricting rubber tube sections of the lines and thereby shutting ofi the flow therethrough. As an example of such a valve, I have shown clamping jaws 32 for shutting off the fiowthrough rubber tube sections 33 and 34 connecting withdrawing channels it to the inlets of pumps P and P respectively. However, for simplicity in illustrating schematically the general arrangement, I have shown (for the purpose of connecting tubes l8 and 21 to connection 23, tubes [9 and 26 to connection 22, tubes 2| and 28 to connection 24 and tubes 20' and 29 to connection 25), two way valves 35, 36, 31 and 38, each of which is in effect two valves having a common connection to connections 22, 23 etc. Each of these valves is adapted to alternately connect a delivery tube to one end of a respective metering unit M, and a return tube to the other end of the metering unit, and to then connect a return tube to the said one end of the metering unit and a delivery tube to the said other end, thereby reversing the direction of movement in the metering unit. The

connections are such that in one half cycle ofoperation, while blood from a patient is being pumped into one end of one metering unit, blood from the donor is being pumped out of the other end of such metering unit and injected into the patient, while blood from the donor is being pumped into one end of the other metering unit and blood from the patient is being forced out of the other end of such other unit and injected into the donor. In the alternate half cycle of operation, the blood that was pumped into the one metering unit from the patient in the preceding half cycle, is moved on to the donor, while the blood that was pumped into the other metering unit from the donor is moved on to the patient. Thus there is a substantially continuous flow in both directions, interrupted only by short intervals in which the reversals take place. This return pumping action is effected by the movement of the piston 3 of the metering unit, moving under the pressure imparted to it by the incoming blood.

Each pump P, P delivers through a connecting tube 39 into a bubble trap T, T and from the traps T, T the blood, with bubbles removed, passes to delivery tubes l8, I9, 20 and 2| through common connection 49 to delivery tubes l8 and 20 and through common connection 4| to delivery tubes I9 and 2|.

At this point it may be noted that the above described delivery and return lines and connections collectively provide two separate pairs of flow circuits, one pair of which is operative to conduct fluid in one half cycle of operation and the other pair of which is operative in the other half cycle of operation. One such pair of circuits includes lines l9 and 21, 29 and 28 and the other includes lines I 8 and 26, 2| and 29. For assistance in placing the four circuits, it may be noted that the respective circuits are shown at the respective four corners of Fig. 1.

The pistons I3 move slowly from one end to the other of their respective cylinders and then reverse their direction and move back to their starting point. The reversal of flow is controlled by valves 35 to 38, and the valves in turn are controlled by the limit movements of pistons |3. As an example of an interlinking control mechanism that can be utilized for controlling the flow in the desired manner, I have shown an electrical system which includes micro-switches 42, 43, 44 and 45, mounted in the respective ends of the cylinders I2, in position to be engaged by the pistons l3 at the limits of their respective strokes. The micro-switches operate mechanism which functions to synchronize the movements of the two pistons so that they will always start their new strokes simultaneously. Thus the same number of strokes is made by each piston. Since the aggregate capacity of chambers I4 and I5 is equal to the aggregate capacity of chambers |6 and H, the same average rate of flow of blood will be maintained in both of the flow circuits that are in operation. Specifically, each micro-switch, when engaged by a piston l3, arrests the circulation of fluid in its particular circuit until the other piston has reached the end of its travel. It is, of course, contemplated that ordinarily the two pistons will end their strokes simultaneously, but should one piston for any cause travel ahead of the other piston in the respective strokes, the micro-switch of the leading piston will function to delay it so that the two pistons can start their next strokes simultaneously. The micro-switches 4 have the further function of effecting the reversal of the valves 35, 36, 31 and 38 when both pistons have completed their respective strokes, and thereby causing the arrested piston to resume its movement. v

Purely as an example of a control system that may be utilized to carry out these operations, I have shown an arrangement in which each micro-switch 42, 43, 44, 45 forms parts of a control circuit including a source of electric power E, a power lead conductor 46, a conductor 41, a relay energizing coil 52, and a ground or return connection 53. The micro-switches, when contacted by their respective pistons, are closed and thereby function to actuate corresponding double relays 48, 49, 5|], 5|, each including an energizing coil 52.

The valves are shifted by an electrically operated mechanism such as, for example, a servomotor 59 including two energizing coils 58, 58 The coils 58, 58 are each controlled by conjoint action of paired relays, both of which must be actuated before the servomotor is energized. servomotor coil 58 is controlled by paired relays 48 and 50. Servomotor coil 58 is controlled by paired relays 49 and 5|. Each of these paired relays servomotor control circuits includes contact heads 54' of the paired relays, sets of contacts 55 and 56 bridged by the respective heads 54, conductors 51 leading from contacts 56 to coils 58, 58 a connection between one contact 55 and power lead 46, and a connection between the other contact 55 and ground or a return connection, indicated at 60. Each pair of relays is thus in series with an energizing coil 58 or 58 and both relays must be closed before the servomotor 59 is actuated to shift the valve. Accordingly, the valve willnot be shifted until both pistons have reached the ends of their strokes.

A second contact head 6| of a respective relay, electrically insulated from the head 54, is adapted to engage contacts 62 and 63, the former connected to the power lead 46 and the latter connected to a bridging conductor 64 which connects the contacts 63 of paired sets of relays together in parallel with the energizing coil 66 through a conductor 61 having a limit switch 68 in series therein. Each limit switch 68 is actuated by the servomotor 59 as it shifts the valves. The limit switches 68 may be spring biased to closed positions and opened by being contacted by the armature of servomotor 59, as indicated. Thus each limit switch will normally maintain a connection between its associated conductors 61 to set up a circuit for energizing a valve solenoid 65 as soon as'the circuit has been closed between the corresponding pairs of relays 48, 50 or 49, 5|.

Before describing in detail the operation of the apparatus, I will describe a number of the novel parts of the apparatus, beginning with the Metering unit The metering unit (Fig. 2), M, N, are chiefly characterized by the fact that the piston l3 floats in the cylinder l2 and responds solely to the pressure of fluids thereagainst. It is of suiiicient axial dimension to maintain a true transverse position within the cylinder I2, avoiding canting and binding, and is fitted with the cylinder l2 with suflicient clearance to move freely back and forth, while permitting only a minimum amount of leakage of fluid between its periphery and the wall of the cylinder.

The problem of leakage has been considered, and the invention provides for an equal leakage in both directions, so that the leakage in one di-' rection will balance the leakage in the other and thereby avoid any inaccuracy in the metering function of the apparatus.

The cylinder I2 and piston I3 are both preferably' constructed of plastic material, and the cylinder I2 may be transparent in order that the action within the metering unit may be observed by the operator. The switches 42, etc., are of thetype known in the trade as microswitches and each includes a plunger III to be engaged by a piston I3. The opening in the end wall of the cylinder, through which th plu'riger'lll passes;

may be sealed in any suitable manner, a's', for example, by means of a flexible diaphragm II covering the plunger, and transmitting move ment to the plunger. Instead of a floating piston, the metering unit may utilize a piston having a piston rod, or may utilize a flexible diaphragm to separate its chambers.

I v Catheter I {Each catheter C (Fig. 3) is of double-tube construction comprising the withdrawal channel III and the injecting channel H,- the withdrawal channel III having a receiving mouthwhich is formed in a bevelled end of the withdrawal channel I llfsaid bevelled end forming an overhanging lip '13: The injection channel II is continued beyond the lip I3 to form a nozzle I4. The overhanging characteristic of the lip I3 functions to prevent the wall of a'veinlS orother occluding membrane from collapsing against the-mouth of withdrawal channel -10 so as to close the same-.- In use, the catheteria'in' accordance with conventional practice, inserted into'a vein as indicated in Fig. 3, the projecting nozzle I4 extending downstream from the receiving mouth so as to minimize commingling of the blood being withdrawn from the vein and that being returned to the vein. In this respect, the invention is 'a definite improvement over existing catheters which are all subject to the objection that-the mouth of the withdrawal tube is frequently closed by the wall of a vein or other surrounding membrane.

Bubble trap The improved bubble trap of my apparatus comprises a reservoir 16 which is positioned vertically when in use, the pump outlet line -39 being connected to an upwardly inclined inlet 11 coinmunicating with the reservoir 16 intermediate its upper and lower ends, and thecommon'connection '40 or being connected to an outlet 18 which communicates with the bottom of the reservoir'lli.

.Qom uni e n h t e teeq re l v 'Itfis amanometer I9 having an upward1yextendingterminal leg 80 to theupper end of which is attacheda mercury trap. The mercurytrap comprisesv a shell 8I having an inlet 82: forming a continuation of the upper end of'leg B0 ,of the manometer and having an'ioutlet 33L Ih e inlet 82 and 'outlet 83 extend into the trap in overlapping relation as" shown in"Fig. '5, 1 so as to'makdt practically:impqssiblefor any mercurypto' be blo'wn'from the inlet"82'throllgh the outlet 83 under any sudden increase of'pressur'e in the bubble trap. The function of the manometer, of course,'is to indicate at all'timesthe pressure of gas which is trapped in the space 84 above the pool of blood 85 inthe bubble trap. Atintervals, the collected gas may beallowed to escape from the chamber at through a. nee-(1mm 86 communicating with and extending upwardly from the top of the reservoir I6. Normally, bleed tube 86 is closed by a clamp valve 81 constrictingly closing a flexible tube nipple 88 on the upper end of the bleed tube 86.

In my apparatus, the bubble trap has an improved operation resulting from the pulsating nature of the pumping action. It appears that because of' the fluctuation in pressure resulting from this pulsating action, there is considerably more of a tendency for the collected gas to be reabsorbed in the blood within the trap thanis the'case where'a "more steady pressure is utilized forfo'rcing the fluid through the system.

Valve unit Figs; '6'and'7 illustrate a preferred arrangement of valve mechanism, and operating means therefor. Fig. 11 discloses how this valve mechanism may bearranged in a cross transfusion system embodying the invention. There are eight valves, each, comprising a section of flexible tubing of rubber or the like, and all actuated by a common'actuator plunger 89. The plunger 89 is siidably mounted in a casing 90 which has a series of bores 9I in which'the valvetubes are mounted; The valve tubes are numbered 35a, 35b, 36a, 36b, 3la, 31b, and 38a, 38b, corresponding to the pairs of ports controlled byv the two way positions of the valves 35, 36, 31 and 38 of Fig, 1, The plunger 89 has a series of operating fingers 9 2 positioned to engage and collapse the tubes 3545351), etc. [In one operative position; of p u er..velve' uhe 35 ;..36a 31b and 38bWi11 be l'collapsed," and in the other 'operative position of the plunger. 89, the valve tubes 35b, 36b, 31a and 38a'will be collapsed (see Fig. 11). i

The plunger 89 is slidable longitudinally in a slideway 94 in the casing 90 (which may be in two halves, securedtogether by bolts 95) and the operating fingers 92 may be accommodated in recesses 96 communicating with the slideway 94.

The valve unitis actuated by an electric servomotor which may take the form of a small electric motor 91 operatinggthrough a reduction gear 98,. an eccentric 99 connected by a pitman I00 to the plunger 89. In degrees of rotation of eccentric 99, the valve plunger will be shifted to one limit of movement while in the balance of one rotation of the eccentric 99, the valve plunger Will be shifted back to itsstarting position, i. e., its alternative operating position.

" I v Pumping unit Each of the pumps P and P comprises a base I04. into which is threaded a pairof adjustable supporting. posts I 05.. The upper ends of the posts. I05 have rotatable connections with a cradle I06, for supporting the same. A flexible tube I01. is supported in a channel its in the cradle I06. An upright I09, rising from the base-I04, base. pair of ears IIII projecting forwardly over the base. Journalledin the ears III] is an operating shaft III which has a pair of cams H2, H2 spaced apart and a pair of eccentric bearings I I 3 located between the cams I I2. The cams H2 may beformed as integral parts of the shaft III, and are arranged at 180 degrees angularity withreference to each other about the axis of the shaft. The eccentric bearings I I 3 are mounted on a reduced central shaft portion H4 which is disposed eccentrically with respect to the axis of the shaft III so as to constitute a crank. A piston or pressure pad H5 is operated by'the crank Ill through a. pair of connectingrods H6 secured to and rising from the piston H5, and pivoted at H I at their upper ends to bearings I I3;

Valve plungers I I8, I I8 arranged one at either end of the piston H5, are operated by the cams I I2 in alternating sequence. The cams H2 are arranged symmetrically on opposite sides of the axis of crank H4, so that, when the shaft III is rotating in one direction, downward movement of piston H will be preceded by downward movement of one of the valve plungers, and when the shaft is rotating in the opposite direction, downward movement of the piston H5 will be preceded by downward movement of the other valve plunger. Thus the direction of flow may, if desired, be reversed by reversing the direction of rotation.

The lower extremities of valve plungers H8, H8 and piston H5 are embraced between the side walls of channel I68 and the upper ends of the plungers H8 and the connecting rods H6 are provided with longitudinal slots H9 which receive a guide rod I29. Thus the valve plungers and connecting rods are guided for vertical reciprocating movement. The ends of rod I20 are mounted in ears III].

In the operation of the pump, rotation of shaft III will, through cams H2 and H3, depress the valve plungers H8, H8 and piston H5 in a sequence depending upon the direction of rotation of shaft III. For example, if the shaft, as viewed in Fig. 9, is rotating in a clockwise direction, it will depress first the valve plunger H8, closing off the tube III! at the left end of piston I I5 as viewed in Fig. 8, will then gradually press the piston H5 downwardly against the tube I01, collapsing the portion thereof between valve plungers I I8 and I I8 and forcing the contents of said tube portion along the tube in the direction indicated by arrow H9. As the piston H5 nears the bottom of its stroke, valve plunger H8 will move downwardly and will close the tube on the right end of piston I I5 as the latter commences to travel upwardly. Valve plunger H8 will move upwardly slightly ahead of the upward movement of piston H5, and the collapsed portion of tube I61 will regain its normal cylindrical shape and will communicate with the adjacent area of the tube to the left of valve plunger H8, drawing a fresh quantity of blood into its interior, which quantity is expelled upon the next downward stroke of the piston H5, in the direction of flow indicated by arrow 4I6.

My improved pump has the advantage of avoiding destruction of any significant number of blood corpuscles. Ordinarily, the piston H5 will be operated so as to collapse the tube III! to a point just short of actual contact between the walls of the tube, in order to avoid crushing the blood corpuscles between the walls of the tube. A slight amount of such crushing will occur where the valves engage the tube but is sufficiently negligible to be unobjectionable.

The pumping rate may be varied by adjusting the height of cradle I66 (through posts I05) and thereby varying the efiective stroke of piston I I5.

Modified arrangement of apparatus In the preferred arrangement of apparatus embodying my invention, shown schematically in Fig. 11, the valve unit of Figs. 6 and 7 is illustrated with the valve tubes 35a, 35b, etc., shown in a somewhat different arrangement from that of Figs. 6 and 7, for the sake of clarity in the schematic lay-out of the complete apparatus. The fluid circulating system is substantially the same as that shown in Fig. 1, and similar reference characters are used to designate the same. Microswitches 68 and 68 are actuated by the respective ends of valve plunger 89 (see Fig. 6). The metering units M and N, and microswitches 42, 43, 44 and 45 associated therewith, are the same as in Fig. l. Relays 46 49 56 and til correspond to relays 48, 49, 50 and 5| of Fig. 1, but are each provided with three sets of contacts instead of two. For each relay, the three sets of contacts are identified with the reference letters a, b and 0 respectively. Contacts a function to set up holding circuits for the respective relay operating coils 52; contacts 1) control the operation of servo motor 91; and contacts 0 control the operating of valve solenoids 66, 66 of clamp valves 32, 32

A source of power E is connected by a main power lead 46 through a series of branch power leads 46a, 46b, 45c and 46a to one side of each microswitch 42, 43, 44 and 45 respectively, and through branch power leads 46c and 46 to one contact of each pair of contacts a. From the other side of each microswitch 42, 43, 44 and 45 respectively, conductors 41a, 41b, 41c and 41d are connected to one side of each of the respective relay coils 52 and are also connected to the other contacts of pairs of contacts a. A conductor I2I connects the other sides of the energizing coils 52 of relays 48 and 56 to ground G through microswitch 68' and conductor I22. Similarly, a conductor I2I connects the other sides of energizing coils 52 of relays 49 and 5I to ground G through microswitch 68 and conductor I22 Motor 91 is arranged to be placed in series with two sets of contacts b. In one phase of operation, motor 91 is energized by the closing of relays 43 and 50 being connected to a contact b of one of these relays by conductors I23 and I23 and being connected to a contact I) of the other of these relays by conductors I24 and I24 In another stage of operation, the motor 91 is placed in series with the contacts I) of relays 49 and 5I being connected to one of such contacts by conductors I23 and I23" and being connected to the other of these contacts by conductors I24 and I24". The co-acting contacts 1) of relays 48 and 5I are connected to branch power leads 46f, and the co-acting contacts b of relays 49 and 50 are connected to ground G by conductors I25, I22 and I25 I22 It will now be apparent that when a pair of relays 48 and 56 (or 49 and 5I are both'energized, one of these relays will connect one side of servo motor III to power source E through conductors I23, etc., whereas the other of the pair of relays will connect the other side of the servomotor 96 to ground through conductors I24, etc.

An auxiliary source of electric power E is connected to one contact of each of the four pairs of contact 0 by conductors I26, I26 I 26". The co-acting contacts 0 of relays 48 and 5I are connected by a conductor I21 to one side of valve operating solenoid 66, and the co-acting contact 0 of relays 49 and 50 are connected by a con- 7 ductor I2I to one side of the other valve operating solenoid 66 The other sides of the respective solenoids 66 and 66 are connected to ground, indicated at G by conductors I28 and I23 respectively.

Relays 48 49 56 and 5| are self opening, i. e., spring biased toward open positions.

Method and operation of apparatus (Fig. 1)

My invention provides an improved method of exchanging blood between a patient and a donor.

in which the blood of the donor is positively pumped into the body of the patient while an equal quantity of blood from the patient is positively pumped into the body of the donor. Such an exchange of blood can be utilized to advantage in the treatment of disease in which the blood of a patient is non-infectious but has an excess of waste products such as urea or bile, or a deficiency of needed elements such as blood sugar, proteins or hormones.

The invention also embodies an improved method of measuring the transferred volumes of blood by (a) counting (as by means of the counter I30 shown in Fig. 1) the numberv of times the valve bank reverses the flow and (b) multiplying by the volume of a metering chamber at its fully expanded condition. v

Extreme accuracy of metering action'fis' obtained by balancing leakage in one direction against the equal leakage in the other direction.

'Any mixing of the. bloods of donor and patient that may resultifrom such leakage is unobjectionable, since the ultimate effect of the apparatus is to'produce a mixture of the donors blood with the patients blood. 1

'In treating a patient, the blood is first treated with an anti-coagulant in accordance with known procedure and the apparatusis then attached by inserting catheters C into veins 15 of the donor A and patient B respectively. The apparatus is startedvsimply by starting theoperation of pumps Pa j I" V a first half "cycle of operation, which may be, for example, that illustrated in Fig. 1, the blood withdrawn from donor A will be pumped by pump P through bubble trap Tinto commonselivery channel 40, from which the two branch delivery channels l8 and. 20 branch off to the respective metering units M and N. Simultaneously, blood withdrawn from the veins of the patient B will be pumped by pump P through bubble trap T into common delivery channel 4| leading to branch delivery channels l9 .and 2|. In this first half cycle of operation, delivery channels 8 and 2|. willbe blocked at the closed ports of valves 36 and 38 respectively, and the fiuidfiow will be directed,v asiridicat'ed by arrows to the onmpo o v ves 35cm. .3 and, en e to, metering unitconnectionsfl and 25 of the re"- spective metering units M and N. Thence the fluid will enter chambers l4 and |6 of the respective metering units and will move 'pistons l3 in the direction indicated by arrows I02, forcing the fiuid out of chambers i and I1, through connections 23 and 24, and through branch return lines '21 and 28, as indicated by arrows |03, to common return lines 3| and 30, and thence to catheter channels into the veins of patient B and donor A respectively. When the pistons |3 reach the ends of their strokes, they will engage and close limit switches 43 and 45, establishing circuits through conductors 4B and 41 and relay energizing coils 52 to close relays 49 and 5|. Theclosing of these relays establishes a circuit which includes power leads 46, relay contacts 54, 55 and 56, conductors 51, and ground 60, to energize servomotor coil 58 and shift valves 35, 36, 31 and 38 to their alternate positions.

Should one of the pistons l3 reach the end of its stroke ahead of the other, the servomotor circuit would remain open because of the coil 58 being in serie with both relays 49 and 5|. During the interim between the completion of the stroke. of V the one piston and the completion of the stroke of the other'piston, a circuit for erfect- 10 ing the interruption of flow to the metering unit in which the piston has completed its stroke, will be established. For example, assuming that the piston of metering unit M has completed its stroke and has closed microswitch 53 while microswitch 45 remains open, a circuit Will be established from power lead 45 through contacts 5|, 52 and 53 of relay 49,'conductors be and iii and limit switch 68 to coil 55 oi valve operator 65, closing constrictor valve 32 against 'nexible tube '34 to shut oil the flow of blood to pump P and thereby arrest the how circuit through metering unit-M while flow through metering unit iv continues, A t the end of the stroke 01' piston N, limit switch 35 Will be closeo. to energize relay 5|, completing the circuit to servomotor coil 55 as described above, causing the servomotor to shift the valves to the alternate position, and opening limit switch 68 to re-establish the fiow passage between patient B and pdllip 1:".

The reversal of the valves establishes a second half cycle of operation, in which blood irom donor Ais pumped'through alternate branch channel i8 and connection 23 to chamber i5 01' metering unit M, while patients blOOd irom chamber I4 is moved through connection 22 to return conduit 26 and thence to common return 35 1mm whlch it is injected into oonor A. Simultaneously, patientsblood will be delivered through branch delivery conduit 2|, valve 38 and connection 24 into chamber ll of metering unit N, while donors blood from chamber l5 will be delivered through c'onnection25gvalve 3T, branch return conduit 29 and common return 3| into the patients veins. At "the end'oi the strokes of the two pistons in thishalf cycle of operation, microswitches 42 and 44. will be closed to establish the circuit through servomotor. coil 58 which shifts the servomotor andvalves back to the positions shown in Fig. 1. Should either piston reach the end of its stroke ahead Oftheother, the fiow to the corresponding metering unit .will be shut off by the action of constrictor valve 32 on connecting tube 33 by a circuit,established through limit switch 58 in a mannersimilar to that described above, and the flow circuit from donor A to pump P, thus tom,- porarily arrested, will be re-established, by the opening of limit switch 68 when the servomotor has ,been shifted back to the position shown in Operation of apparatus of Fig. 11

[The operation of the apparatus of Fig. 11 is similar to that of the apparatus of Fig. 1, the main difierence being the somewhat different arrangement of electrical connections that are setup. 'Assumingeach piston l3 to be in the middle of its stroke, moving in the direction. indicated' by 'arrow|29, the flow through the lines I8, '26, 2 I" and 29 will be as indicated by the arrows adjacent to those lines, and the lines I9, 21, 20 and 28 will be shut off by the closing of valves 35b, 36b, 31a and 38a respectively. Microswitches 68 and 68 at the respective ends of valve actuator 89 will 'be closed and open respectively. When the pistons l3'reach' the ends of their respective strokes, they will close microswitches 42 and 44. As each of these switches is closed, it willestablish a circuit from source of current E through conductor 56' and branch conductor 46a (or 550), conductor 41a (or Me), to an energizing coil 52 of a' respective relay 48 (or 50 grounded through conductor -|2| (or HP), microswitch 68 (or6-8 ),:and conductor |22'(or I22 As each or theseirielays is energized, it will establishia) 11 a holding circuit through contacts a from power lead 46f through its respective energizing coil 52 'to ground throughconductors I2I (or HP), etc.;

(b) a circuit to one side of servomotor 91 through contacts I) from power lead 46f through conductors I23 I23 (or I23", I23) and (c) acircuit to a corresponding valve operating solenoid 66 (or 66 through contact from power lead I26, etc., to conductor I27 (or I21 to ground connection I28 (or I28 closing the respective valve 32 (or 32 When both relays 48 and'50 have been energized, a circuit through servomotor 9! will be completed, from powerlead 46] through contacts I) of relay 48 conductors I23 I23 to the servomotor, thence from the other side of the servomotor to conductors I24, I24 contacts b of relay 50 and thence to ground through conductors I25. It will now be apparent that this servomotor energizing circuit goes through both of the pair of relays 48 and 50 in series, and that the servomotor is not energized until both relays have been closed. The servomotor Will operate, transmitting movement from eccentric 99 to valve plunger 89 until the latter has shifted to its alternate position, opening valves 35b, 36b, 31a and 38a, closing valves 35a, 36a, 31b and 38b, and opening microswitch 68, thus breaking the ground connection to the energizing coils of relays 50 and 48 and causing both of these relays to resume their open position. All contacts a, b and 0 will be thereby opened, resulting in: (a) releasing the holding circuits; (b) ole-energizing the servomotor 91 and stopping the movement of valve plunger 89 at its alternate position; and (c) de-energizing both valve solenoids 66 and 66 thus re-opening the valves 32, 32 to re-establish flow in both flow circuits. In an early stage of the movement of valve plunger 89, the microsvvitch at 68 is released and consequently returns to its closed position, setting up the ground connections to ground G from energizing coils 52 of relays 49 and EN. During the ensuing half cycle of operation, pistons I 3 will move in the direction opposite to the directions indicated by arrows I29, metering the flow of blood through the alternate circuits including flow lines I 9, 21, 20 and 28, now open. At the end of this half cycle of operation, limit switches 43 and 45 will be closed, energizing relays 49 and SP, again closing valves 32 and 32 and operating servomotor 91 in the manner described above, but through the alternate circuits including (b) a servomotor circuit from power lead 46f through contact I) of relay 5| conductors I23", I23, I24 and I24, contact I) of relay 49 and conductor I25 to ground through limit switch 68 (c) valve operating circuit from power lead I26 through contacts 0 of relay 5I and conductors I21 and I28; and valve operating circuit to solenoid 65 from power lead I26" through contact 0 of relay 49 and conductors I21 and I28 I claim:

1. In a blood transfer apparatus, in combination with a pair of catheter means for insertion into blood channels of respective bodies, each including an injection device and a withdrawal device, a pair of metering units each including means defining opposed fluid chambers, and a movable element separating said chambers and movable in response to fluid pressure in one of the chambers; a pair of pumps; and a plurality of conduits and valves interconnecting said pumps, catheter means and metering units to provide two sets of flow circuits one of which is operative in one half cycle of operation of said apparatus to direct blood from the respective bodies into one end of each of the respective metering units while directing flow from the other ends of the respective metering units into the respective bodies, and the other of which is operative in a second half cycle of operation to direct flow from the respective bodies into the said other ends of the respective metering units while directing'flow from the said one ends of the respective metering units into the bodies.

2. Apparatus as defined in claim 1, including means automatically operable at the ends of the strokes of the respective movable elements of said metering units to reverse the positions of said valves.

3. Apparatus as defined in claim 1, including a bubble trap interposed between the discharge side of each pump and the flow circuits connected thereto.

4. Apparatus as defined in claim 1, wherein said metering units each comprise a cylinder and a floating piston therein adapted in response to the pressure of fluids pumped into on chamber thereof to expel the fluid from the other chamber thereof.

5. Apparatus as defined in claim 1, wherein said metering units each comprise a cylinder and a floating piston therein adapted in response to the pressure of fluids pumped into one chamber thereof to expel the fluid from the other chamber thereof, each metering unit including limit switches at its respective ends, engageable by the piston at the end limits of its stroke, and electrical means controlled by said limit switches for shifting said valves.

6. In a blood transfer apparatus, in combination with catheter means for insertion into blood channels of respective bodies, including a withdrawal device and an injection device; a pair of metering units, each including means defining opposed fluid chambers, said means including a movable element separating said chambers and movable in response to fluid pressure entering one of the chambers to drive fluid out of the other chamber; a pair of pumping units, each having an inlet communicating with a respective withdrawal device, and each having an outlet; a pair of delivery conduits branching from each of said outlets; a plurality of return conduits arranged in pairs, a common return connection between each pair of return conduits and a respective one of said injection devices; connections to the respective ends of each of said metering units, a plurality of valves operable in a first half cycle of operation to establish communication between a connection at one end of eachrespective metering unit and one set of said delivery conduits while simultaneously establishing communication between the connections at the other ends of said metering units and one set of said return conduits and, in a second half cycle of operation, to establish connections between said one ends of the metering units and the other set of said return conduits While simultaneously establishing connections between said other ends of the metering units and the other set of delivery conduits.

,7. In apparatus as defined in claim 6, electrically operated means including switches atthe respective ends of said metering units for automaticallyefiecting the shifting of each of said valves from its one position to its alternative position at the-end of the stroke of a movable element.

a pssa 8. Apparatus as defined in-claim 6, wherein said conduits are so arranged that in one half cycle of operation, one delivery conduit and one return conduit will connect the respective chambers of one metering unit to one of said bodies while another delivery andreturn conduit will connectthe respective chambers of the other metering unit to the other body, while in an alternative half cycle of operation,alternative delivery and return conduits will connect said other and said one chamber of each metering unit to said other and said one body respectively, whereby in the first half cycle of operation blood from the one body is injected into the one chamber of one metering unit and blood from the other body is ejected from the other chamber of said one metering unit into said one body, while blood from the other body is being injected into the one chamber of the other metering unit and blood from the one body is ejected from the other chamber of said other metering unit and delivered to said other body; whereas in the other half cycle of operation, blood from the one body will be delivered into the said other chamber of said other metering unit while blood from the other body is being delivered from the one chamber of said other metering unit to said one body, and blood from the other body will be delivered to the other chamber of said one metering unit while blood from said one body is being delivered from said one chamber of said one metering unit to said other body.

9. In a blood transfer apparatus, a pair of metering units each including a movable element and means defining on the respective sides of said movable element a pair of chambers, flow connections to the respective chambers at the respective ends of each unit, a pair of conduits branching from each of said flow connections, and valves controlling each of said conduits, said valves comprising flexible tubes arranged in opposed banks and a reciprocable pressure member movable from a position simultaneously engaging one bank of tubes and closing the same to a position simultaneously engaging and closing the other bank of tubes.

10. In a blood transfer apparatus, in combination with catheter devices for insertion into blood vessels of respective bodies, including a pair of withdrawal devices and a pair of injection devices: a pair of metering units each including means defining opposed fluid chambers, said means including a movable element in each unit, separating the chambers thereof, said elements being movable to increase the volumes of one pair of chambers while decreasing the volumes of the other pair of chambers; said means further including a fluid connection for each chamber; a system of flow conduits including a pair of conduits for each of said fluid connections, leading respectively to an injection device for one body and a withdrawal device for the other body, and valve means arranged to render one series of said conduits, consisting in one conduit of each pair, collectively operative in one half cycle of operation, to conduct flows from the withdrawal devices to one of said pairs of chambers and from the other pair of chambers to the injection devices, and to render the other conduits of the respective pairs operative, in the other half cycle of operation, to conduct flows from the withdrawal devices to said other pair of chambers and from said one pair of chambers to the respective injection devices.

tion with catheter devices for insertion into blood vessels of respective bodies, *including a pair of injection devices and a pair of withdrawal. devices: means defining two pairs of metering chambers and afluid connection for each chamber for conducting flows alternately'into and out of the respective chamber; a system of flow conduits including a pair of conduits for each of said fluid connections, leading respectively to an injection device for one body and a withdrawal device for the other body; and valve means arranged to render one series of said conduits, consisting in one conduit of each pair, collectively operative in one half cycle of operation, to conduct flows from the withdrawal devices to one of said pairs of chambers and from the other pair of chambers to the injection devices, and to render the other conduits of the respective pairs operative, in the other half cycle of operation, to conduct flows from the withdrawal devices to said other pair of chambers and from said one pair of chambers to the respective injection devices.

12. In a blood transfer apparatus, in combination with catheter devices for insertion into blood vessels of respective bodies, including a pair of injection devices and a pair of withdrawal devices: means defining two pairs of metering chambers and a fluid connection for each chamber; means for inducing flows alternately into and out of the respective chambers; a system of flow conduits including a pair of conduits for each of said fluid connections, leading respectively to an injection device for one body and a withdrawal device for the other body; and valve means arranged to render one series of said conduits, consisting in one conduit of each pair, collectively operative in one half cycle of operation, to conduct flows from the withdrawal devices to one of said pairs of chambers and from the other pair of chambers to the injection devices, and to render the other conduits of the respective pairs operative, in the other half cycle of operation, to conduct flows from the withdrawal devices to said other pair of chambers and from said one pair of chambers to the respective injection devices.

13. In a blood transfer apparatus, in combination with a pair of catheter devices for insertion into blood vessels of respective bodies, said devices including a pair of injection devices and a pair of withdrawal devices; means defining a plurality of metering chambers and a fluid connection for each chamber to function alternately as inlet and outlet; means for inducing flows alternately into and out of the respective chambers; a system of flow conduits including a pair of conduits for each of said fluid connections, leading respectively to an injection device for one body and a withdrawal device for the other body; and valve means controlling the flows through said conduit system, including a valve for each conduit, said valve means comprising a series of flexible tubes each constituting a portion of a respective conduit, said flexible tubes being arranged in opposed banks, and a reciprocable pressure member movable from a position simultaneously engaging one bank of tubes and closing the same, to a position simultaneously engaging and closing the other bank.

PETER F. SALISBURY.

(References on following page) RE RENCES CIT-E1) I 7' The following referencesare otrecord in the UNITED STATES PATENTS j 1,481,794 Dupir} Jan. 29, 1924 Name "Daie Janes Mar. 31, 1925 McMurdo Dec. 25, 1928 f Gundlach June 11, 1929 i Lante'rnier Apr. 8, 1930 Kipp Nov. 8, 1932 Webb' Sept. 24, 1935 Cooley Nov. 15, 1938 Wirta'uen et a1. Apr, 22, 1941

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