US 3799702 A
A pressure sensor is connected to the suction tube of an apparatus for draining blood from a wound and supplying it to a heart-lung machine. Means, which may be either a separate pump or the pump connected to the tube for pumping blood, forms an underpressure generator. The pressure sensor is responsive to a first underpressure in the tube for increasing the pumping action of the suction pump motor, and to ambient pressure for decreasing the pumping action of the pump motor. The sensor may also be responsive to a greater underpressure for stopping or reversing the motor.
Description (OCR text may contain errors)
United States Patent [1 1 Weishaar APPARATUS FOR DRAINING BLOOD FROM A SURGICAL WOUND AND TRANSMISSION TO A HEART-LUNG MACHINE Inventor: Egon Georg Weishaar, 8000 Munich 2, Erzglessereistrasse 29, Munich, Germany Filed: Nov. 15, 1972 Appl. No.: 306.937
US. Cl 417/38, l28/278, 417/477  Int. Cl.... F04b 49/00, A6lm l/OO, F04b 43/12  Field of Search 128/276-278, 128/297-300, 350 V, 230; 417/38, 36, 44, 45, 325, 326, 477
Q  References Cited UNITED STATES PATENTS 3,457,865 7/1969 Dunlap 417/36 Mar. 26, 1974' 3,565,076 2/1971 Kadan 128/278 Primary Examiner-Carlton R. Croyle Assistant Examiner-Arnold Ward Attorney, Agent, or Firm-W0lfgang Passe  ABSTRACT A pressure sensor is connected to the suction tube of an apparatus for draining blood from a wound and supplying it to a heart-lung machine. Means, which may be either a separate pump or the pump connected to the tube for pumping blood, forms an underpressure generator. The pressure sensor is responsive to a first underpressure in the tube for increasing the pumping action of the suction pump motor, and to ambient pressure for decreasing the pumping action of the pump motor, The sensor may also be responsive to a greater underpressure for stopping or reversing the 9 Claims, 2 Drawing Figures APPARATUS FOR DRAINING BLOOD FROM A SURGICAL WOUND AND TRANSMISSION TO A HEART-LUNG MACHINE BACKGROUND OF THE INVENTION The invention relates to an apparatus for draining blood from a surgical wound and the transmission of this blood to a heart-lung machine and is particularly directed to apparatus of this type which employs a suction tube adapted to connect the wound with a suction pump.
Difficulties have arisen in the past in the use of this type of apparatus for draining blood from wounds, since air is entrained with the blood when the blood level is lowered to the level of the tube mouth, which is held adjacent the wound, thereby causing foaming of the blood. Such foaming of the blood effects a considerable degradation of the blood, and it is difficult to remove the foam from the heart-lung machine.
This adverse effect has been dealt with in the past by providing a manually controlled switch for on and off operation of the pump as required. This manual control, however, necessitates an additional assistant or, in case it is done by the surgeon himself, requires his special attention. In the latter case, since the surgeons attention is fully occupied by the operation itself, the manual actuation of the pump switch may be overlooked.
The most objectionable aspect of this inadvertent failure to use the manual switch operation resides in the potential damaging effect on the blood and in the possibility that the mouth of the suction tube may suck itself onto some internal body organ. In such event, it may be necessary to free the tube mouth from the wound by force. An additional objectionable feature is occasioned by the necessity of providing a special transmission line for the actuation of the switch, which may create a problem with regard to the required sterility.
OBJECTS OF THE INVENTION It is an object of the present invention to provide means for eliminating the problem as described above and to safely automate the correct performance of the drainage operation.
It is a further object of this invention to provide an economical apparatus for automatically controlling the pump ofa blood draining device so that the foaming of the blood is prevented.
SUMMARY OF THE INVENTION According to the invention the above objects are achieved by providing a suction tube coupled to a weakly acting underpressure generator and to a pressure sensor. The pressure sensor, upon discerning a predetermined first pressure drop due to the blood level rising above the mouth of the suction tube is connected to switch the suction pump on for a gradual speed-up. Upon discerning a second predetermined higher underpressure value, the suction pump is switched off and connects the suction tube to atmospheric pressure. Upon the disappearance of any underpressure due to the blood level falling below the mouth of the suction tube, the pump is switched off. As a result, the suction pump is immediately shut off as soon as the blood level falls below the mouth of the suction tube such that the above mentioned air entrainment cannot take place. During this operational state,
in which the blood level is below the mouth of the suction tube, the underpressure generator and the pressure sensor continually monitor the blood level, thereby assuring the drainage of blood as soon as the blood level rises sufficiently, while also monitoring if the suction tube has sucked itself onto a body organ. This, to be sure, can also happen during normal blood drainage, e. g. due to displacement of the suction tube and sudden attachment to a body organ.
The underpressure generator can be a small separate machine or alternatively the suction pump itself may be used for this purpose, in which case it is set to a lower output mode of operation.
The connection of the tube to atmospheric pressure may be effected in various ways. For instance, the suction tube may be provided with a valve connecting the tube to the ambient atmosphere by automatically opening as soon as the second predetermined underpressure value is reached. On the other hand, the suction pump may be employed for this purpose by setting it for a lim ited time on pressure operation. In this case the mouth of the suction tube will automatically free itself from any part of the body to which it may have attached itself by suction.
BRIEF FIGURE DESCRIPTION FIG. 2 illustrates an arrangement employing a separate small machine as an underpressure generator, in.
accordance with a further embodiment of the invention.
DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS Referring now to FIG. 1, a suction tube 1 is inserted into a wound via the elbow 2. The blood level in the wound is indicated by a wavy line 3. The suction tube 1 is connected to a suction pump 5 in a heart-lung machine 4, and the blood is pumped from pump 5 to other not illustrated components of the heart-lung machine. In the illustrated arrangement a so called rollerpump is used, in which two rollers 6 and 7 supported by an arm 20, rotate about the dashed line axis 8, thereby squeezing the elastic suction tube 1. During rotation, the roller 6 squeezes the blood that is contained in the suction tube ahead of it in a forward direction, at the same time sucking blood behind itself until it arrives at the position occupied by the roller 7 as illustrated. Then the roller 7, which has now reached the position which roller 6 previously occupied, repeats the same action. Both rollers are driven via the shaft 8 (not shown) on the axis by the motor 9.
The roller pump 5 not only serves the purpose of draining the blood from the wound, but also serves as underpressure generator. In serving as underpressure,
tube mouth 12, the slowly advancing rollers 6 and 7 of the roller pump '5 create an underpressure in the suction tube 1. A pressure sensor 10 is provided in order to monitor these actions. The pressure sensor 10 responds as soon as an underpressure of about mm water column is attained, thereby. actuating the electronic control unit 11 which in turn then effects a gradual speed-up of the motor 9. The gradual speed-up of the motor is controlled by a conventional electronic delay element in the control unit 11. The roller pump 5 is now on a suction mode of operation, whereby an underpressure of up to 50 cm water column may be produced. From now on the blood reaching the tube mouth 12 will be continually drained off. When the blood level again falls below the tube mouth 12, the pressure in the suction tube 1 rises to atmospheric pressure again, thus allowing the pressure sensor to return to its zero position and, upon passing the first threshold value of 5 mm water column, to reset the motor via the electronic control unit 11 to the low speed which is appropriate for the action of the roller pump 5 as underpressure generator. This alternate rise and fall of the blood level relative to the tube mouth 12 repeats itself continually. The entrainment of air in blood as previously described, however, does not take place since the roller pump actually feeds blood only during periods when the blood level 3 is higher than the tube mouth 12, while acting merely as underpressure generator as soon as the blood level 3 falls below the tube mouth 12. As long as air can enter the tube mouth 12, the slow movement of the rollers 6 and 7 will not entrain air in any blood into the tube mouth 12. As soon as the tube mouth 12 is closed again by the rising blood level, the roller pump 5 will gradually run up to its'full suction mode of operation.
In order now to detect the occurence of the tube mouth having sucked itself against some body part, which may happen during the draining of blood as well as in the case illustrated by FIG. 1, the pressure sensor is provided with a second threshold value at a higher underpressure, e. g. at 100 cm water column. Upon closure of the tube mouth 12 by some body part, the roller pump will operate as in the case of blood drainage or will start up for this operating mode if the blood level is below the tube mouth 12. In the latter case a rise of the blood level is simulated by the closure of the tube mouth. However, since no blood is being sucked in, the underpressure in the suction tube 1 increases. Upon reaching the second threshold value the pressure sensor will activate the electronic unit 11, which in turn shuts off the motor 9 andcauses the pressure in the suction tube to rise to atmospheric pressure, thereby facilitating removal of the tube mouth 12 from the body part. This procedure is initiated by reversing the direction of rotation of the motor 9 by the electronic device 11, thereby causing the roller pump 5, by turning in the reverse direction to that indicated by the arrow in the illustration, to produce pressure in the suction tube 1. As soon as the pressure in the suction tube reaches atmospheric pressure, the tube mouth 12 will detach itself or may easily be removed from the body organ.
The above described procedure provides a very gentle manner of blood drainage, the blood never being subjected to sudden movements. Conventional pressure sensing devices and threshold circuits may be employed in the system of FIG. 1.
The apparatus shown in FIG. 2 containsseveral of the same elements as in FIG. 1, which therefore carry the same reference indices. In this embodiment of the invention, a separate suction pump 13 is provided as underpressure generator. This pump is connected to the suction tube via the check valve 14. The suction pump 13 runs continuously, thus providing instantaneous effectiveness as soon as the blood level 3 falls below the tube mouth 12. When the blood level 3 rises again the suction pump 13 generates the above underpressure, which, upon reaching the first threshold value, activates the pressure sensor. The latter then, via the electronic unit 11, turns on the motor 9, which then drives the roller pump in the above described manner for the blood draining operation. The higher underpressure in the suction tube created thereby cannot influence the suction pump 13, because now the check valve 14 effectively separates the suction pump 13 from the suction tube 1.
Transmission of atmospheric pressure to the suction tube 1 in the case of closure of the tube mouth 12 by some body part is provided via the valve 15. The latter is opened by the electronic unit 11 when the underpressure in the suction tube 1 has risen to the second threshold value of the pressure sensor 10. Opening of the valve 15 allows air to enter the suction tube 1, thus permitting the tube mouth 12 to be easily removed or to detach itself from a body organ.
It should here be mentioned, that the valves 14 and 15 may be combined in a two-way control valve. It is also feasible in the arrangement of FIG. 2 to have the pump 5 reverse direction of rotation in order to generate atmospheric pressure in the suction tube 1 as has been described in reference to FIG. 1. It may, however, be pointed out that the separate underpressure generator pump provides the advantage of allowing the roller pump 5 to stand still as long as the blood level 3 is below the tube mouth 12, thereby eliminating any manipulation of the blood contained in the roller pump 5 during this phase of operation.
Although the invention has been described with reference to specific example embodiments, it is to be understood that it is intended to cover all modifications and equivalents within the scope of the appended claims.
What is claimed is:
1. An apparatus for draining blood from a surgical wound and transporting this blood to a heart-lung machine by means of a suction tube connected to a suction pump; said apparatus comprising weakly acting underpressure generator means, a pressure sensor, means for connecting said suction tube to said underpressure generator means and to said pressure sensor, means for connecting said pressure sensor to said pump for controlling the latter, said pressure sensor being further responsive to a predetermined first underpressure threshold value due to a rise of the blood level above the mouth of the tube for gradually starting up the suction pump, said pressure sensor being responsive to a second higher underpressure value for turning off the suction pump and transmitting atmospheric pressure to the suction tube, said pressure sensor being further responsive to the disappearance of the underpressure due to the blood level dropping below the suction tube mouth for shutting the pump off.
2. The apparatus according to claim 1, wherein said underpressure generator means comprises said suction pump, being automatically set to low operating mode of operation. v
3. The apparatus according to claim 1, comprising a valve for connecting said suction tube to ambient, atmospheric pressure and means for connecting said valve to said pressure sensor for opening the valve in response to the occurence in said tube of a second underpressure value.
4. The apparatus according to claim 1, comprising means for reversing said suction pump whereby it starts gradually to produce temporarily positive instead of negative pressure and whereby atmospheric pressure is supplied to said suction tube.
5. In an apparatus for draining blood from a wound and. supplying it to a heart-lung machine, wherein the apparatus includes a suction tube, a pump connected to the suction tube, and a motor connected to operate the pump, the improvement comprising pressure sensing means connected to sense pressure in said tube for controlling said motor, said pressure sensor being responsive to a first underpressure for controlling said motor to increase the pumping action of said pump, said pressure sensor further being responsive to ambient pressure for controlling said motor to decrease the pumping action of said pump, and means for producing an underpressure in said tube.
6. The apparatus according to claim 5, wherein said means for producing an underpressure comprises said pump.
7. The apparatus according to claim 5, wherein said means for producing an underpressure comprises a second pump connected to said tube.
8. An automatic system for draining fluids comprising a suction tube, a pump connected to said tube, a motor connected to operate said pump, a pressure sensor connected to control said motor in response to the pressure in said tube, and underpressure generating means for reducing pressure in said tube, said pressure sensor being responsive to a first underpressure for controlling said motor to increase the pumping action of said pump, said pressure sensor being further responsive to ambient pressure in said tube for controlling said motor to decrease the pumping action of said pump.
9. The system according to claim 8, wherein said pressure sensor is responsive to an underpressure in said tube greater then said first mentioned underpressure for controlling said motor to reverse the pumping action of said pump.