Blood withdrawing device

Abstract

A blood withdrawing device for use in measuring blood withdrawn from a donor includes a frame on which is mounted a weight responsive device. In one form there is a balance beam fulcrumed on the frame and carrying a suspended tray for supporting a blood container having a supply tube under control of a pinch valve on the frame. The balance beam is continually balanced by a movable weight on the balance arm, the weight being advanced and retracted by an electric motor under control of a counter so that when a predetermined weight of blood is in the container the pinch valve is automatically actuated to stop the blood flow. During filling of the container the tray is mechanically agitated so as to intermix the incoming blood with an anticoagulant in the container. The agitation or shaking is periodically interrupted as the blood flows in and is terminated shortly before the final weighing, then reinitiated upon completion of total draw.

Description

In the withdrawal of blood from a donor, particularly a human donor, it is highly advisable, and is sometimes required, that the quantity of blood withdrawn not exceed a particular value. The value is often based on the weight of the donor and while it may not exceed a set quantity, it is often desired to vary the setting in order not to exceed the limit yet to acquire blood up to the set limit. It is also often advisable to utilize an anticoagulant with the blood just withdrawn so that during the withdrawal process and thereafter the blood is kept without any substantial coagulation. It is also advisable to make the withdrawal process as nearly automatic and free of possible human errors as may be and to afford an easy and effective withdrawal process.

To these ends it is an object of the invention to provide a blood withdrawal device that can easily be utilized in the process of blood withdrawal and can accurately and efficiently be worked by personnel who may not be highly skilled.

Another object of the invention is to provide a blood withdrawal device that measures the withdrawn blood quite accurately by weight, and volume.

Another object of the invention is to provide a blood withdrawal device in which the withdrawn blood is maintained in an optimum condition during withdrawal.

Another object of the invention is to provide a blood withdrawal device having the desired attributes, yet which can be embodied and maintained in quite a simple, direct manner.

Another object of the invention is to provide a blood withdrawal device that is flexible in its operation so that varying parameters can easily be set and maintained.

Another object of the invention is in general to provide an improved blood withdrawing device.

Other objects, together with the foregoing, are attained in the embodiments of the invention described in the accompanying description and illustrated in the accompanying drawings, in which:

FIG. 1 is a diagram showing the logical or functional layout of one form of blood withdrawing device pursuant to the invention;

FIG. 2 is an elevation of one form of blood withdrawing device with a large portion of the casing broken away to show the interior construction;

FIG. 3 is a cross-section, the plane of which is indicated by the line 3--3 of FIG. 2;

FIG. 4 is a view similar to FIG. 2 but showing a modified form of blood withdrawing device; and

FIG. 5 is a diagram similar to FIG. 1 but disclosing the arrangement of the modified form of device.

In one arrangement there is provided, as particularly shown in FIG. 2, a frame 6 partly in the form of a housing 7 designed to enclose and support various of the attendant mechanisms on feet 8 resting on any suitable supporting surface 9, such as a table or stand.

To receive the blood withdrawn from the donor, there is a container 11, usually a flexible bag, which is provided with a supply tube 12 leading to the customary hypodermic needle and passing through a pinch valve 13, when open permitting free fluid flow but when closed inhibiting flow through the tube 12 into the container 11. The valve 13 is suitably mounted on the frame 6 so as to be readily accessible to an operator for introducing the tube into the valve and for withdrawal of the tube therefrom.

The container 11 is placed upon a supporting tray 16 movably mounted on the frame 6. The tray is especially contoured to accept and confine the container 11 and to permit easy placement of and removal of the container. The tray is provided with a special mounting in connection with a mechanism sensitive to the weight of the container and its contents. While blood quantity can be dealt with either in terms of volume (in milliliters) or in terms of weight (in grams, and usually in a range from zero to a thousand grams or so), we prefer to calibrate all measurements herein in terms of volume, bearing in mind, however, that it is blood weight which is being directly measured.

For this purpose the frame 6 journals an aligned pair of rotatable stub shafts 17, also termed fulcrum or fulcrum shafts, serving as the central mounting for a balance beam, generally designated 18. Included in this arrangement and secured to the pivot shafts 17 is a pair of lower links 19 which move in unison with the shafts 17. The lower links 19 form part of a parallelogram linkage also including a pair of upper links 20 fulcrumed at one end by pins 21 on the main frame 6. At the other end, the lower and upper links are connected by pivots 22 and 23 to a pair of intervening links 24. A cross bar 25 is secured to the beam 18 and also connnects the ends of the links 19 adjacent the stub shafts 17. Thus, the balance beam 18 and the links move in unison. The rocking movement of the balance beam 18 about the axis of the fulcrum shafts 17 and of the pairs of links 19 and 20 is productive of a nearly vertical motion of the pair of intervening links 24.

The tray 16 is pivoted on the pivot pins 23 at its opposite ends, thereby enabling the tray to swing laterally about the axis of the pins 23. Also, the tray can move virtually vertically up and down as the weight of the tray varies. The vertical motion of the tray 16 is transmitted to the links 19 and the cross bar 25 and causes corresponding rocking movement of the balance beam 18 about the axis of the stub pivot shafts 17.

It is important that blood supplied to the container 11 through the tube 12 be maintained in appropriate condition. This is effectuated by providing the container 11 initially with a supply of an anticoagulant. To insure that the anticoagulant and the entering blood are thoroughly intermixed and are maintained so, the suspended tray 16 is agitated by swinging or oscillation generally about the axis of the pins 23 as a center. For that reason on the frame 6 there is mounted an electric drive motor 26 having a crank pin 27 rotated thereby and connected through a pitman 28 to a pivot pin 29 positioned in parallel linkage relationship to the pivot pins 22 and 23. When the motor 26 is energized the tray 16 is rocked side-to-side about the axis of the pins 23. This motion or agitation intermixes and comingles the anticoagulant and the blood so as to maintain the blood in proper condition.

In accordance with the arrangement the balance beam 18 is rocked about the fulcrum 17 as the weight on the tray 16 decreases and increases. To maintain the balance beam close to its central, balanced condition, there is provided thereon a screw shaft 31 journalled at both ends in extensions of the balance beam and having gearing 32 connecting the screw shaft to a motor 33 mounted on an L-shaped bracket 35 secured to the base of the housing 7.

Engaging the screw shaft 31 is a dependent weight 34. When the motor 33 is properly energized, its rotation is transmitted through the gearing 32 correspondingly to rotate the shaft 31. This moves the weight 34 toward and away from the fulcrum shaft 17 in a corresponding fashion. If the weight 34 is appropriately positioned at a sufficient distance from the fulcrum, the weight of the container 11 or of the container and its contents is exactly balanced.

Since there is a slight relative angular movement between the two gears of the gearing 32 as the balance beam moves, the periphery of the upper gear 30 on the shaft 31 is somewhat rounded, as appears most clearly in FIG. 2, to maintain engagement with the lower gear 40 driven by the motor 33 despite any slight rocking movement of the shaft 31 and gear 30. Meshing of the two gears 30 and 40 occurs at a point coincident with the axis of the fulcrum shaft 17.

In order to make sure that balance occurs, an appropriate mechanism is provided. The balance beam 18 has an extension 36 with an optical aperture 37 therein. In a balanced condition of the beam 18 the aperture 37 is in exact alignment with an optical scanning device 38 having a source and receptor of light. When the beam is out of position, a characteristic reflection causes a correction; and when the beam 18 is in position, the light is transmitted but not reflected to the structure 38, so no correcting impulse is supplied thereby. Stated differently, when the beam 18 is out of position because it is too heavy and the aperture 37 is lowered, then the mechanism 38 is energized to cause the motor 33 to restore the balance condition by properly moving the weight 34. A similar but reverse correction occurs when the beam is out of position because it is too light.

In addition, the extent of rotation of the shaft 31 and, correspondingly, the radial position of the weight 34 from the axis 17 is indicated by the location of a disc 41 fixed on the end of the shaft 31. The disc 41 has spaced apertures and intervening solid reflectors effective upon an optical device 42 similar to the arrangement with the device 38. The structure is such that the disc 41, being provided with a predetermined number of especially spaced apertures, gives a series of indications to the device 42 representative of discrete, rotary positions of the shaft 31. In this way, as will appear from a discussion of the logic diagram, the momentary actual weight on the tray 16 is indicated and compensated for. When a suitable tray weight is attained, the mechanism for maintaining a substantially equal balance comes to an end condition. Under those circumstances the valve 13 is actuated to shut off further blood flow. The operator can then remove the so-indicated or measured or weighed quantity of blood by removing the container and can replace the container 11 with another, empty one for a repetition of the cycle.

In more detail, as shown particularly in FIG. 1, the arrangement is at least logically, somewhat more elaborate. Within the casing 7 and available from the surface thereof, there are decimal set wheels 51, 52 and 53, or thumbwheels. These can be arranged initially by the operator for a predetermined quantity, in three order terms, of blood to be acquired (e.g., 761 grams, about 720 milliliters). The settable wheels 51, 52 and 53 are effective to set a standard in a count comparator 54 as a base to compare with the blood input.

It is to be noted, incidentially, that although the operation of the balance beam mechanism is based upon blood weight, the wheels 51, 52 and 53 are calibrated in terms of volume, viz. milliliters (ml.), since most operators are more familiar with volume measurements.

Having introduced into the machine the measure of the desired amount of blood to be acquired, the operator then observes a first ready light 56 on the casing surface. When illuminated, this light indicates that the machine is clear or free and ready for use with the balance weight 34 in start position.

The operator then depresses a start switch 57. That action sends an impulse to a balance drive motor control logic unit 58 which immediately returns a signal illuminating the start switch 57 to show that the mechanism is in proper condition to proceed. Since successive containers 11 may vary in weight, the logic unit 58 first sends an impulse to the balance drive motor 33 and moves the weight 34 to balance the empty container and to set a starting point for blood weighing. When this is done, a second ready light 59 is illuminated and a "flow on" switch 60 is enabled. When the switch 60 is actuated by the operator, a signal goes to a flow pinch-off logic unit 61 which sends a return signal to illuminate the switch 60. The signal to the unit 61 operates a flow pinch-off solenoid 71. This opens the pinch valve 13 to permit blood flow into the container 11. Also, the logic 58 continues the signal to the balance drive motor 33. Drive power is derived from a power supply 62 connected to the usual source through a manually controlled power switch 63 and itself supplying power through suitable leads to all power users in the mechanism. The balance drive motor 33 is thus enabled to advance and retract the weight 34 so as to maintain very nearly an exact balance with the changing, usually steadily increasing, weight on the tray 16. At any time blood flow can be stopped by pressing a "flow off" switch 64. This simply closes the valve 13 by deenergizing the solenoid controlled by the unit 71. Flow can be resumed by pressing the switch 60.

At the time the balance logic 58 is energized, there is also energized an interlace unit 66 which normally is effective to pass a control signal to the agitation drive motor 26 to energize that motor and so agitate or oscillate the tray 16.

In passing through the interlace logic unit 66, the control for the agitation drive motor may not be but preferably is subject to periodic interruption. It is believed that the agitation need not be continuous but can appropriately be interrupted at intervals to improve the accuracy of weighing. The agitation may be periodically interrupted at set intervals and resumed thereafter. This agitation is usually interrupted to provide a clear reading of the weight mechanism. That is to say, the optical balance sensor 38 which controls the logic element 58 to advance or reverse the motor 33 is slightly more accurate in between operations of the drive motor 26. For example, the first five seconds of an interlace cycle is quiet to permit blood weighing. The next fifteen seconds are for agitation. The final five seconds are without agitation so the blood may become quiet. The twenty-five second cycle is repeated indefinitely until a set period just before final weighing.

The described operation continues with respect to the balance until such time as the weight position responsive device 42 has arrived at a certain point or number of counts. This point is achieved a selected or predetermined number of milligrams of weight before the final value as set into the comparator 54. This function is particularly accomplished by a look ahead buffer unit 67 deriving its impulses from the interlace timing logic unit 66.

This arrangement operates fundamentally on the output of the optical count encoder 42 responsive to the position of the weight 34 and in discrete increments responding to the advancement of the weight along the balance beam. Each time the impulse device 41 energizes the encoder 42 the count is entered into a counter 68 which affords a count in a decimal mode. The counts are not only entered into the counter 68 but are also relayed into a "draw" digital display 69 so that the supervisor or user can at any time assess the progress of the blood withdrawal. The counts are accumulated in the counter 68 and are also effective upon the look ahead buffer 67.

The look ahead buffer 67 subtracts a predetermined number of counts from the total number of counts manually set into the comparator 54. The buffer 67 transmits to the count comparator 54 the actual number of counts. When this equals the set-in value less the arbitrary number of accounts, the comparator 54 does several things. For one, it sends an impulse to the interlace timing logic 66 and interrupts the operation of the agitation drive motor 26. Thus, in the final phase of blood withdrawal there is no longer any oscillation or agitation of the tray and the container, and the mechanism is quiet for accurate final weighing. In addition, an impulse goes to the balance drive motor logic 58 so that in a predetermined number of further pulses the balance drive motor 33 is stopped. Equally important, an impulse to the flow pinch-off logic 61 occurs after the correct number of counts and an impulse goes through a normally closed load switch to the flow pinch-off solenoid control 71. This immediately causes the tube 12 to be clamped and no further blood to enter the container 11.

Since the predetermined amount of blood has then come into the container 11 and the cycle to that extent is completed, the count comparator impulse to the balance drive motor control logic 58 reverses the balance drive motor 33 and retracts the weight 34 to an initial position. In such position the returned weight actuates a limit switch 72 which shuts off the motor 33 with the balance in home position, ready for the next cycle; and it also energizes the ready light 56 indicating that the machine is then ready for another cycle. The ready light 56, bing illuminated, again enables the start switch 57 so that the next cycle can be manually started at any time.

As a precaution and a safeguard there is also provided a reset switch 74 which can be manually actuated at any time to stop the operation of the mechanism by stopping the balance drive motor control logic unit 58, by interrupting the operation of the interlace timing logic unit 66 and by actuating the pinch-off logic unit 61 to energize the solenoid so that the tube 12 is clamped. The reset switch 74 is for terminating a draw for any reason, emergency or otherwise, prior to reaching full draw. By depressing the reset switch 74, the machine is reset to zero (ready for a new cycle) by activating the motor 33 in the reverse direction until the weight 34 contacts the limit switch 72 and stops.

In this fashion there is provided a means for automatically controlling the amount of blood withdrawn from a donor, for automatically stopping the flow of blood at the predetermined point, for agitating the withdrawn blood with an anticoagulant during the operation, for stopping the agitation during critical or final weighting and for affording a variable quantity of withdrawn blood for regulating operation of the machine. As previously indicated, all display elements, such as the draw digital display 69, as well as the thumbwheels 51, 52 and 53 are calibrated in terms of blood volume (ml). In like manner, all controls, switches, labels and even the balance mechanism 18 are calibrated in terms of milliliters (1 ml=1.057 gm).

In most instances the weight measurement is done by the balance weight mechanism shown in FIG. 2 and 3. But this can also be accomplished by a variant means, as shown in FIGS. 4 and 5. For the most part the arrangement of these figures is identical with that shown in FIGS. 1, 2 and 3 except for mechanism peculiar to the operation of the balance arm mechanism. In this instance there are provided manually presettable register wheels 81, 82 and 83 into which can be initially set the weight in milliliters of blood to be withdrawn. These in turn introduce their set values into a count comparator 84 comparable to the comparator 54. The mechanism is started by the manual actuation of a start switch 86 which controls an auto zero buffer 87 having several functions. One of the functions is for the buffer 87 to condition an analog digital converter 88 to be receptive to analog signals from a weight sensor 89 in the form, usually, of a load cell incorporating its own bridge electronics.

The weight sensor is conditioned by the actual weight on the tray and converts such weight into an analog in electrical current impressed upon the converter 88 which puts out equivalent pulses or counts. The auto zero buffer 87 has another output which is effective upon an interlace timing logic unit 91 comparable to the element 66. When energized the unit 91 is effective to enable an agitation drive motor 92 comparable to the motor 26 so that the tray is appropriately agitated or oscillated. The energized converter 88 produces output signals to a "draw" digital display 93. The display element 93 is comparable to the display element 69 and shows to the user, in volumetric terms, the amount of blood withdrawn up to the time of reading.

The converter 88 likewise sends pulses to a look ahead buffer 94 comparable to the look ahead buffer 67. This may automatically add a predetermined number, say 50, digits to the weight generated output of the converter 88. The artificially augmented value is introduced into the comparator 84.

In the comparator 84 when the artificially increased value is received a pulse is sent to two destinations. One is into the interlace timing logic 91 to interrupt the agitation drive motor 92 a set, short interval before the blood withdrawal has been completed. The other portion of the impulse from the comparator 84 goes into a flow pinch-off logic element 96 comparable to the element 61. This is effective when energized, upon receipt of a second, final load pulse from the comparator, through a normally closed load switch to actuate a flow pinch-off solenoid 97 effective upon the pinch valve 13, just as before, and so to stop the withdrawal of blood.

In the present arrangement there is also provided a flow on switch 98 comparable to the switch 60 in FIG. 1 which can be energized to actuate the logic 96 to open the pinch-off solenoid 97. Similarly, there is a flow off switch 99, like the switch 64, effective when actuated through the pinch-off logic 96 to close the pinch-off valve 13 through its solenoid control 97.

In this way the flow can be started and stopped at any intermediate part of the cycle, if the operator so chooses.

In this arrangement, as well, the mechanism is effective to measure an amount of blood as it is being withdrawn, keeping a very close indication thereof, and agitating the container for the blood in order to maintain its mixture with an anticoagulant, and finally stopping the agitation shortly before the end of the withdrawal so that the weighing mechanism is not interfered with during the final part of the withdrawal and can accurately stop the withdrawal at the indicated amount by operation of the pinch valve. During the operation there is a display of the amount of blood momentarily available in the container.

Also, the start switch 86 in energizing part of the mechanism causes the automatic zero buffer 87 first to take the tare weight of the container and then to zero the weight mechanism in order that the blood withdrawn will have a net weight value and so that the weight of the container will not adversely affect the measured and indicated weight of blood withdrawn.

Claims

What is claimed is:

1. A blood withdrawing device comprising:

a. a frame;

b. a load measuring device on said frame, said load measuring device being a balance beam;

c. a tray adapted to support a container having a supply tube;

d. means for connecting said tray to transmit a load thereon to said load measuring device;

e. means on said frame for controlling the flow of blood through said tube; and,

f. means actuated by said load measuring device for operating said controlling means including:

a weight mounted for movement along said balance beam,

a motor for moving said weight long said balance beam,

means for effectuating a number of counts in accordance with said movement,

means for accumulating said counts, and,

means effective at a predetermined number of counts for disabling said motor.

2. A device as in claim 1 including means for changing said predetermined number.

3. A device as in claim 1 including means for mounting said tray on said balance beam for agitation relative thereto, and means on said frame for agitating said tray relative to said balance beam.

4. A blood withdrawing device comprising:

a. a frame;

b. a load measuring device on said frame, said load measuring device being an electrically responsive pressure device;

c. a tray adapted to support a container having a supply tube;

d. means for connecting said tray to transmit a load thereon to said electrically responsive pressure device;

e. means on said frame for controlling the flow of blood through said supply tube; and,

f. means actuated by said electrically responsive pressure device for operating said controlling means.

5. A device as in claim 4 in which said electrically responsive pressure device includes a weight sensor conditioned by said load on said tray, said weight sensor being capable of converting said load into an electrical current analog; means for converting said electrical current analog into equivalent counting pulses; means for accumulating said counts; a solenoid actuated pinch valve connected to said supply tube; and means effective at a predetermined number of counts to close said pinch valve.

6. A blood withdrawing device comprising:

a. a frame;

b. a load measuring device on said frame;

c. a tray adapted to support a container having a supply tube;

d. means for connecting said tray to transmit a load thereon to said load measuring device;

e. means on said frame for controlling the flow of blood through said supply tube;

f. means actuated by said load measuring device for operating said controlling means;

g. means for mounting said tray on said load measuring device for agitation relative thereto;

h. means on said frame for agitating said tray relative to said load measuring device; and

i. means for interrupting the operation of said agitating means at predetermined intervals to provide readings of said load in static condition.

7. A device as in claim 6 in which said interrupting means is operable during the loading of said tray and at termination of blood flow.

8. A device as in claim 7 including means actuated by said load measuring device for operating said controlling means.