United States Patent 3731680

The invention disclosed is for a pressure monitor and control device having particular utility in medical technology were constant monitor of hydro-static pressure is required. The disclosed device is especially useful in a method for effecting extra-corporeal hemodialysis.

Wright, Floyd A. (Charleston, SC)
Hargest, Thomas S. (Charleston, SC)
Application Number:
Publication Date:
Filing Date:
Primary Class:
Other Classes:
128/DIG.3, 210/90, 210/109, 210/137, 210/646, 604/118
International Classes:
A61M1/36; (IPC1-7): B01D31/00; B01D13/00; A61B19/00; A61B5/02
Field of Search:
128/DIG.12,13,214E,214B,214F,214R,218A 210
View Patent Images:
US Patent References:
3526481BLOOD OXYGENATOR1970-09-01Rubricius
3197068Apparatus for monitoring the dispensing of liquid1965-07-27Corbin et al.
2721732Apparatus for mixing liquids and gases1955-10-25Melrose
2705493Extracorporeal circulation device pumping system1955-04-05Malmros et al.
2689565Blood pump1954-09-21Gobel
2569748Strainer apparatus1951-10-02Grave

Primary Examiner:
Medbery, Aldrich F.
What is claimed is

1. In a method for extra-corporeal hemodialysis wherein blood is pumped through venous tubing from a patient into a dialysis assembly having means for effecting dialysis of waste materials from the blood and into a dialysis fluid flowing through the dialysis assembly, with further means for passing dialyzed blood through a debubbler prior to return through a venous tubing to the patient, the improvement which comprises:

2. The method of claim 1 wherein said monitoring of the pressure of the debubbler is by a transducer.

3. The method of claim 1 wherein said clamping is effected using an electromechanical clamp.

4. An electro-mechanical pressure monitor and control system for controlling the flow of blood through a tube connected to the circulatory system of a body, during extra-corporeal hemodialysis, which system comprises in combination, a fluid pressure monitor means disposed in communication with an electronic amplifier, said amplifier disposed in further communication with an electro-mechanical clamp, said clamp having a reversible motor and a position screw terminated by a relatively movable anvil, said relatively movable anvil disposed for effecting or removing clamping pressure on said tubing by being positionable between the relatively movable anvil and a relatively stationary anvil, said relative stationary anvil being hand positionable for initial positioning relative to the said tubing, a debubbler, a venous tubing connected thereto, and a pump disposed relative to tubing receiving blood from a patient, said pressure monitor means disposed relative to the debubbler, means responsive to said pressure monitor to operate said clamp disposed relative to the venous tubing to provide a means for which a fall of pressure sensed at the debubbler results in relative clamping of the venous tubing and an increase of pressure sensed at the debubbler results in relative removing of clamping of the venous tubing.

5. The system of claim 4 wherein the pressure monitor means is a transducer.

6. The system of claim 4 wherein an alarm sensor is in communication with a warning device and the pressure transducer.

7. The system of claim 4 wherein warning devices are in communication with an alarm sensor which further monitors signals from the means for monitoring the pressure of the debubbler.

This invention relates to a pressure monitor and control device. More particularly, the present invention provides a pressure monitor and control device for use in a method for extra-corporeal hemodialysis for minimizing dangers of equipment malfunction as well as minimizing attention required by an operator of the system.

Devices are known to the art for effecting extra-corporeal hemodialysis. These devices are typically employed as a therapeutic measure when kidneys no longer perform their blood purifying function resulting in accumulation of toxic wastes in the blood. In hemodialysis, blood is made to flow between semipermeable membranes which permit passage of toxic wastes into a circulating dialysis solution, while restricting passage of blood. Toxic wastes in the blood, notably urea, creatinine, uric acid, and other deleterious products move through the semipermeable membranes because of the difference in the concentration gradient between that present in the blood, and that of the dialysis fluid, the latter being essentially zero.

During extra-corporeal hemodialysis, the operation must be precisely controlled and monitored as blood moves from its normal physiological confines to the extra-corporeal environment for processing.

Typically, prior art dialyzers require constant attention for signs of blockage or restricted flow and do not provide means for regulating and monitoring these effects relative to the patient. Accordingly, the present invention provides means for positive monitor and control of pressure, with further means for activating an alarm system in the event pressure varies beyond a pre-established range.

Generally stated, the present device includes a pressure monitor means disposed relative to a debubbler in the blood return line of a dialysis machine. Pressure may be monitored from air vents of the debubbler, and by means which communicate this pressure monitor with an electro-mechanical clamp on the venous tube, control of blood circulation may be maintained. The electro-mechanical clamp includes a reversible motor connected, if required, through a speed reduction unit for driving a movable anvil relative to venous tubing and a stationary anvil.

In the method of operation using the device of the present invention, a decrease of pressure sensed by the pressure monitor means effects, through appropriate electrical circuity, a signal to drive the movable anvil against a venous tube in a tube closing direction. By effecting a closing pressure or restriction in the tubing there results a counter increase in the pressure of the blood in the system. The reverse sequence is effected when the pressure monitor means senses an increase in pressure of blood in the dialysis system with resulting opening of the restriction applied by the movable anvil onto the venous tubing. In the event of pressure loss, such as by rupture or clogging of the venous tube, or a loss of electrical power, the pressure monitor means and the associated electrical circuity causes an alarm to activate along with effecting disabling of the hemodialysis machine by the movable anvil and dialysis pump control means.

Referring to the drawings in which like elements are designated throughout the several views:

FIG. 1 illustrates in block diagram operation of the present invention;

FIG. 2 illustrates in perspective view the present pressure monitor and control device in position on a venous tube;

FIG. 3 illustrates diagrammatically the positioning and method of operation of the present device during extra-corporeal hemodialysis;

FIG. 4 is a side elevational view of the electromechanical clamp of the present device taken in partial section;

FIG. 5 is a left side elevational view of the clamp of FIG. 4; and

FIG. 6 is a right side elevational view of the clamp of FIG. 4.

Referring to FIG. 1, where the general sequence of operation of the present invention is illustrated, electrical power controlled by a switch is supplied to the unit. Next, tubing is positioned in the electro-mechanical clamp described in detail subsequently, and adjusted to obtain a desired pressure which is read from a gauge. The unit after being connected to the dialysis machine is ready for operation. The electronic amplifier responding to signals of pressure monitored by a transducer taken through a pressure set point relative to the venous tubing causes the electro-mechanical clamp to either tighten or release clamping relative to the venous tubing depending upon whether increase or decrease of pressure is desired. Should failure of the system result, a signal is provided from the transducer such as if pressure failure results causing an alarm to sound or other warning device to activate, as desired.

FIG. 2 illustrates the pressure monitor and control device of the present invention generally illustrated as portable unit 10 having control box 12, and electromechanical clamp 14 disposed about venous tubing 16. Operation of unit 10 in extra-corporeal hemodialysis is more particularly illustrated in FIG. 3.

In FIG. 3, patient 20 is prepared for extra-corporeal hemodialysis according to conventional practice. Also, the dialyzer is similarly prepared such as by effecting prior rinse, sterilization, testing and the like prior to actual operation. After all the equipment has passed check-out, hemodialysis begins. Whole blood is received through tube 22 from the patient by conventional pump 24 suited for extra-corporeal dialysis such as a peristaltic or roller pump 26. This blood proceeds through line 28 into conventional dialysis assembly 30. Correspondingly, dialysis fluid in line 27 is pumped into assembly 30 from which it is removed with waste substances through line 29. The composition of dialysis fluid may be changed in accordance with the therapy required for a particular patient. Generally, compositions of dialysis fluid are described in "Hemo-dialysis for Chronic Renal Failure" by Freeman, Maher & Schreiner in Annals of Internal Medicine, Vol. 62, No. 3, March 1965. A temperature control may be provided, as desired, with heating means to properly control and maintain the temperature of the dialysis fluid at a prescribed level.

As blood moves from the radial artery inlet tube 22, it proceeds to dialysis assembly 30 in between semipermeable layers where dialysis is effected and out by line 31 to debubbler 32 from line exit 34. From the debubbler, the blood proceeds through venous line 16 to the vein of patient 20 by outlet 37. Meanwhile, fresh dialysis solution under action of suitable pump means is drawn through line 27 and into interstitial compartments of dialysis assembly 30. Although fresh dialysis solution is indicated as passing through assembly 30 to outlet 29 in parallel flow to blood passing through the unit, it is recognized that other flow patterns including countercurrent flow may be used as desired.

Toxic wastes dialysates such as urea and the like proceed through line 29 for removal from the unit by conventional practice.

Connected to dialysis assembly 30 is pressure monitor and control device 10 of the present invention. Electromechanical clamp 14 of device 10 is positioned on venous tubing 16, with electrical connection to pump 26 for control of the pumping action in the event of blockage or zero pressure in the assembly. Pressure monitor and control device 10 further includes line 36 with associated pressure reading means attached to debubbler 32. Pressure of the debubbler is monitored by the reading means illustrated as a gauge and the signal therefrom is returned to device 10 for electrical interpretation. Electrical power is presented into device 10 by outlet 38.

The electro-mechanical clamp 14 is illustrated in greater detail in FIGS. 4-6. Clamp 14 includes speed reducing gear unit 39 receiving drive from reversible motor 40. Unit 39 is mounted onto end plate 41. End plate 41 is maintained in relative position from front plate 43 by spacers 42 and bolts 45.

Through gear unit 39, positioning screw 44 is connected to enter advance or retract movable anvil 46 relative to a positionable anvil 48 normally fixed after initially set. For practical purposes of this invention, anvil 48 is considered as being fixed although it is recognized that relative movement thereof is possible using turnable hand set 50 within L-shaped support block 52.

Also illustrated as parts of the electro-mechanical clamp 14 are block 47 which insures accurate movement of movable anvil 46, and venous tubing 16 disposed between movable anvil 46 and anvil 48.

In operation of device 10, electro-mechanical clamp 14 is positioned on venous tube 16 and anvil 48 is moved to establish a predetermined pressure by clamping against tube 16. The moveable anvil 46 is then controlled by increasing or decreasing pressure of tubing 16. This pressure will be determined by the pressure monitored at debubbler 32. Should the pressure begin to fall within venous tubing 16, motor 40 will activate moving anvil 46 to restrict fluid passage within tubing 16 thereby resulting in an increase of pressure in the system. The converse also results should an increase in the pressure of the system be sensed through debubbler 32. In the event the pressure of the system drops to zero by clogging or the like, a signal is transmitted from device 10 through line 25 to terminate the pumping action of pump 26. In the latter situation, alarm sensors and warning devices as previously indicated may be actuated.

The various elements of the present apparatus unless otherwise indicated may be secured to adjoining elements by any suitable means such as bolts, welding, rivets or the like. In addition, auxiliary support of reinforcement members may also be included as part of the apparatus where required.

Although a preferred embodiment of the invention has been illustrated herein, it is to be understood that various changes and modifications may be made in the construction and arrangement of elements without departing from the spirit and scope of the invention as defined.