US2899636A

US2899636A - rubricius

Info

Publication number: US2899636A
Authority: US
Priority date: 1957-08-06
Filing date: 1957-08-06
Publication date: 1959-08-11
Anticipated expiration: 1976-08-11
Also published as: GB834986A; DE1066318B

Description

pm EM w Aug. 11, 1959 J. L. RUBRICIUS BLOOD LOSS DETERMINING DEVICE Filed Aug. 6, 1957 INVENTOR JEANETTE 1.. RUBRICIUS ATTORNEY 5 United States Patent 2,899,636 BLOOD LOSS DETERMINING DEVICE Jeanette L. Rubricius, Jamaica, N.Y.

Application August 6, 1957, Serial No. 676,559

5 Claims. (Cl. 324-30) The present invention relates to a method and an apparatus for determining the blood loss from patients during surgical operations after trauma and during childbirth.

In the field of surgery, it is important in many instances to ascertain the amount of blood lost by a patient during an operation. Heretofore, such determination has been diflicult to make. During surgery, the major portions of blood lost from patients is absorbed by sponges and gauze disposed in the critical areas of the surgery and when these are removed, a considerable amount of blood collected therein becomes coagulated making a volumetric determination of the blood a dimcult problem.

Accordingly, it is an object of this invention to produce an apparatus and a method of accurately determining the blood lost from a patient during a surgical operation.

Another object of the invention is to provide a method and apparatus which will accurately and continuously determine the amount of blood lost from a patient at any unit of time during surgery.

Still another object of the invention is to produce an apparatus for determining blood loss during surgery which is simple to operate and may be fabricated easily and economically.

In a preferred embodiment, the invention comprises a container. with an agitator adapted to extract blood from sponges, gauze and the like, means connecting the container to a suction device which is in communication with an operating site, electrodes positioned within the container and connected with a mil-balancing conductivity bridge through a servomotor whereby the conductivity of the solution may be read in terms of blood loss.

Certain other advantages and objects will become apparent from the following detailed description of the invention and the accompanying drawing showing a partially cut-away and schematic illustration of the instant invention.

Referring to the figure, there is shown an exterior housing '10 having an opening in the top portion thereof adapted to receive acontainer 12. The container 12 is provided with an outlet passage 14 formed in the bottom wall thereof with a screen protector 15 mounted on the inner side of the container. A vacuum pump 18 is provided having communication with the outlet 14 through a coupling pipe 16. The pressure side of the pump 18 is provided with a pipe 20 which extends upwardly and passes through the exterior of the housing 10. It will be noted that the pipe 20 is provided with a curved end portion 24 which is pivotally mounted to the pipe 20 by means of a swivel coupling 22.

The inlet side of the pump is connected to a suction pipe 26 which is provided with a valve 28. The pipe 26 is adapted to extend to the operating site and is employed to provide a path for blood lost directly at the operating site to the container 12 through the suction pump 18, pipe 20 and the curved outlet 24.v

ice

A motor 30 is mounted on the exterior side wall of the container 12 and is adapted to drive an agitator member 32 which is disposed on the inner surface of the container and may be driven by a conventional output shaft of the motor 30. The agitator member 32 may be of the conventional designs, such as, for example, the agitator members of the small apartment size Washing machines.

In practice, the container 12. is initially filled with a measured volume of distilled water 34 or any substance of known electrical conductance or resistance.

It has been found advantageous to place a perforated basket 36 in the container 12 so that the gauze sponges disposed therein are contained and are not allowed to float loosely in the container in which case they have a tendency to plug the drain 15. The basket 36 may be formed of screen or other perforated material. The basket 36 enables the sponges to be readily removed from the container 12 after they have been compressed of their fluid at the conclusion of an operation and may then be easily and quickly counted. In addition, the basket 36 provides means which militate against the splashing of the fluid 34 when the level thereof is beneath the agitator 32 as in emptying.

The basket 36 is provided with a flanged rim 38 adapted to rest on the upper marginal edge of the container 12, thereby permitting the main body of the basket 36 to be suspended within the container.

An A.C. Wheatstone bridge circuit is employed to measure the concentration of blood which is present within fluid 34 in the container 12. The Wheatstone bridge is a balanced circuit including three known resistances and one unknown resistance with a source of current at line frequency and a device for detecting the potential difference. In this Wheatstone bridge circuit, a conductivity cell 40 constitutes one arm. Another arm consists of a temperature compensator 42, which may be either automatic or manual. The third and fourth arms, 44 and 46, respectively, consist of calibrating resistors and a variable resistance 48. The variable resistance 48 is a calibrated slide wire arrangement. The Wheatstone bridge circuit is energized with a power supply (alternating current) which is connected be-. tween the conductivity cell 40 and the fourth arm resistor 46 and the temperature compensator 42 and the third arm resistor 44 in the conventional manner. The output of the Wheatstone bridge network is sensed across the bridge at the point on the variable resistance 48 determined by the slide wire contact 50 and the point 51 between the conductivity cell 40 and the temperature compensator 42. Any voltage resulting from an unbalance in the bridge network is applied to the primary winding of a transformer 52 which feeds a signal proportional to the unbalance to an amplifier 54. The output of the amplifier 54 is operative to energize a motor 56 which is of a reversible type. A negative going signal fed to the motor 56 is operative to energize the motor in one direction while a positive going signal is operative to drive the motor 56 in the opposite direction.

The motor 56 is mechanically coupled to the sliding contact 50 of the variable resistance 48 and also to a meter 58 which is calibrated in terms of blood loss. The armature of the motor 56 is directly coupled to the meter 58 so that the rotation of the armature Will cause simultaneous movement of the indicating needle of the meter.

It has been found that by using distilled water in the container 12 the initial conductance of the fluid 34 is negligible. Any subsequent changes in conductivity are brought about by the addition of blood into the fluid. When the blood, which is two phase, consisting of both cells and serum, is added to the distilled water the blood becomes hemolysed; IIhat isythe red blood cells'are ruptured by diluting the whole blood with water, thereby liberating the intracellular electrolytes into the solution and thus varying the conductivity of the fluid 34 within the container 12. Since the initial conductance of the water known, the quantity of water is known, the conduc'tance of the blood added is known, the only unknown uantity is the amount of blood which has been added;

It will be appreciated that during an operation, blood soaked sponges, gauze and the like may be manually disposed within the container 12 and will be agitated by the agitator '32 so that the blood clots and fluid blood may be removed therefrom and become a portion of the fluid 34. 'It will also be appreciated that by connecting the pipe 26 to the operating site, the vacuum pump 18 will be operative to suck the blood from the operating site through valve 28 through the pipes '26 and '20 out through the outlet end 24 into the fluid 34 within the container 12. As the blood content of the fluid 34 varies, the conductivity of the fluid will likewise vary proportionally. This change in conductivity may be sensed by the conductivity cell 40 which forms one arm of the Wheatstone bridge network.

In operation, the bridge is initially balanced so that the output E will be nearly zero. When the blood content of the fluid 34 is increased the resistance changes in the measuring arm and likewise the voltage E increases. The phase of this voltage is determined by the direction of change of the resistance. The resultant voltage output of the bridge is amplified by the amplifier 54 and is fed to the field winding of the reversible motor 56. The motor 56 is mechanically connected to the arm of the slide wire resistor 50 and is driven in a direction that will reduce the voltage, E to again be nearly zero. Simultaneously with balancing the bridge, the motor 56 drives the meter 58 which has been calibrated in terms of blood loss. When the voltage E becomes zero, the motor 56 will stop, thereby allowing a positive and continuous reading of the meter 58 during the course of an operation of the blood loss. It will be readily apparent that the motor 56 may, in certain instances, overcorrect in which case the bridge unbalances in an opposite direction causing the motor 56 to reverse to completely balance the bridge through the variable resistance 48. In such case the indicating needle of the meter 58 will return to its proper position in unison with the motor 56 properly indicating the amount of blood contained within the container 12.

The temperature compensator 42 is in the circuit to electrically correct for changes in the temperature of the solution. The compensator 42 adjusts for temperature through the change of resistance of the compensator, which may be a thermistor, .inserted in the fluid 34. Either the manually adjustable type of resistance or the thermistor may be used in the instant circuit without departing from the scope of the invention.

Upon the termination of an operation, it is necessary to remove the fluid 34. To this end, the curved pipe 24 is turned to the position shown in dotted lines, the pump 18 is energized, and the fluid 34 may thereby be conveniently removed from the container 12.

While the illustrated embodiment of the invention shows the conductivity cell 40 and the temperature com pensator 42 positioned within the container 12, it will be apparent that the objects of the invention maybe likewise achieved by disposing these elements within the pipe 16.

It will be clearly apparent from the above description that the invention herein set forth produces a new, novel and eflicient method and apparatus for determining accurately during the course of an operation or childbirth the amount of blood which is lost by the patient.

I claim:

1. An apparatus for determining blood loss comprising in combination, a container, at fluid contained within said container, a fluid impervious basket disposed within said container, agitator means disposed within said container for extracting blood from blood soaked materials disposed within said fluid, suction means for providing communication between said container and an operating site, a null-balancing conductivity bridge circuit, and electrodes disposed within said container and forming at least one arm of said bridge circuit for detecting changes in conductivity of said fluid. I

, 2. An apparatus for determining blood loss comprising a container for containing a fluid, a fluid impervious basket disposed within said container, an agitator disposed within said container, means providing communication with said container and an operating site, a nullbalancing conductivity bridge circuit, one of the arms of said circuit including a conductivity cell disposed within said container, another of the arms of said circui-t including a'temperature responsive resistance element disposed within said container, and means c'onnec'tedto said bridge for metering any unbalance thereof.

3. An apparatus for determining blood loss comprising a container for containing a fluid, an agitator disposed within said container, means providing communication with said container and an operating site, means for recirculating the fluid contained in said container, a null-balancing conductivity bridge circuit, at least one arm of-said bridge including a conductivity cell, said conductivity cell disposed within said container, and means connected to said bridge for metering any unbalance thereof.

4. .A method for determining blood loss during surgical operations consisting of adding blood to a fluid of known electrical conductivity, agitating the blood to liberate the intercellular electrolytes and protein and continuously sensing the conductivity of the composite fluid by a null-balancing conductivity bridge circuit whereby the amount of bloodin said fluid is determined.

5. A method of determining blood loss during a surgical operation comprising introducing lost blood and blood-soaked materials into a body of fluid in a confined zone whereby the blood is diluted and intercellular electrolytes and protein are liberated into the fluid, continuously sensing variations in the electrical conductivity of the composite fluid in said confined zone, and utilizing the variations in electrical conductivity to determine the amount of blood collected in said zone.

References Cited in the file of this patent UNITED STATES PATENTS 2,192,123 Bennett Feb.'2 7, 1940 2,621,235 Jewell Dec. 9, 1952 2,687,139 Noble et a1 Aug. 24, 1954 UNITED STATES PATENT OFFICE CERTIFICATE 0F CU ECTIUN Patent No, 2,899,636 August 11, 1959 Jeanette Lo Rubricius It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, lines 12 and 22, for "impervious", each occurrence, read pervious Signed and sealed this 12th day of January 1960a (SEAL) Attest:

KARL H, AXLINE ROBERT C. WATSON Commissioner of Patents Attesting Officer