Title:
BLOOD-GAS SEPARATING SYSTEM FOR PERFUSATE CIRCULATION
United States Patent 3849071


Abstract:
A blood-gas separating chamber provides an inlet for receiving oxygenated blood along with undissolved gas from an oxygenator unit through a constant displacement pump and further provides an outlet for supplying oxygenated blood free of undissolved gas for corporeal perfusate circulation. A liquid-gas separating element connected between the inlet and the outlet liberates undissolved gas from the blood while a second outlet located at the upper portion of the separating chamber is connected to return blood and separated gas from the upper portion of the chamber back to the oxygenator unit. A freely movable valve member is positioned within the chamber to be responsive to the liquid and gas and moves between a fully open position for permitting the free flow of gas and liquid through the second outlet and a plurality of modulating positions including a position of maximum restriction of the second outlet for permitting a controlled flow of liquid and gas therethrough. One embodiment employs a valve seat at the second outlet having three inwardly protruding projections for permitting a continuous flow of blood and gas through the second outlet while another embodiment employs three projections on the movable valve member.



Inventors:
KAYSER K
Application Number:
05/391651
Publication Date:
11/19/1974
Filing Date:
08/27/1973
Assignee:
KAYSER K,US
Primary Class:
Other Classes:
96/406, 128/DIG.3, 137/202, 137/433, 422/112
International Classes:
A61M1/36; (IPC1-7): A61M1/03
Field of Search:
137/202,433 55
View Patent Images:
US Patent References:
3717174PERFUSION SAFETY VALVE1973-02-20Dewall
3527572APPARATUS FOR TREATING BLOOD1970-09-08Urkiewicz
3502440BLOOD OXYGENATOR1970-03-24Tompkins
3458085VALVE FOR FUEL STORAGE TANKS1969-07-29Clemenson
3194439Vortex cavity seal float1965-07-13Beduerftig
2927582Pump-oxygenator1960-03-08Berkman et al.
2913068Air eliminator1959-11-17Mestarz et al.
2896620Blood arterializing method and apparatus therefor1959-07-28Tremblay
2603493Automatically vented liquid flow regulating valve1952-07-15Rusconi
1151329N/A1915-08-24Audett et al.
0386173N/A1888-07-17



Primary Examiner:
Richman, Barry S.
Attorney, Agent or Firm:
Andrus, Sceales, Stark & Sawall
Parent Case Data:


This is a division of application, Ser. No. 317,421, filed Dec. 21, 1972.
Claims:
I claim

1. A blood-gas separating system for perfusate circulation, comprising a blood supply, blood transfer means connected to said supply for adding a gas to be dissolved by the blood received from said supply and supplying blood containing the dissolved gas, and a blood-gas separating means including a blood conducting first outlet supplying blood for perfusate circulation and a second outlet, said separating means receiving blood containing dissolved gas and any undissolved gas from said transfer means and separating undissolved gas from the blood containing dissolved gas and passing blood free of undissolved gas through said blood conducting first outlet for perfusate circulation and including valve means responsive to the presence of blood and undissolved gas within said separating means, said valve means controlling the flow through said second outlet and providing a maximum open valve position when large accumulations of undissolved gas is present in said separating means thereby permitting the free flow of undissolved gas through said second outlet and a position for maximum restriction of said second outlet when large accumulations of blood free of undissolved gas is present in said separating means thereby permitting a controlled flow of gas and blood through said second outlet.

2. A blood-gas separating system for perfusate circulation, comprising a blood supply, blood transfer means connected to said supply for adding an oxygen gas to be dissolved by the blood received from said supply and supplying oxygenated blood to a blood transfer means outlet, and a blood-gas separator including a housing defining a chamber having an inlet receiving oxygenated blood including dissolved and undissolved gas from said transfer means outlet and a blood conducting first outlet supplying blood for perfusate circulation and a second outlet including return means supplying gas and blood to said transfer means, said separator including means located within said chamber for separating undissolved gas from the oxygenated blood and passing blood free of undissolved gas through said first outlet and a valve means responsive to the presence of blood and undissolved gas within said separator chamber, said valve means controlling the flow through said second outlet and providing a maximum open valve position when large accumulations of undissolved gas is present in said chamber thereby permitting the free flow of undissolved gas through said second outlet and a position for maximum restriction of said second outlet when large accumulations of blood free of undissolved gas is present in said chamber thereby permitting a controlled flow of gas and blood through said second outlet.

3. The system of claim 2, wherein said valve means includes a float operating to said position of maximum restriction in response to the accumulation of blood free of undissolved gas within said chamber so that blood and dissolved gas passes through said second outlet and said return means to said transfer means.

4. The system of claim 2, wherein said transfer means includes an input means connected to said return means and operates to provide a pressure differential between said second output and said transfer means input.

5. The system of claim 2, wherein said valve means includes a float having a specific gravity which is 95 percent of the specific gravity of blood for providing proper modulation of said second outlet.

6. The system of claim 2, wherein said return means connecting said second outlet to said transfer means includes a translucent material providing a visual indication of the return flow of blood.

7. The system of claim 2, wherein said separator inlet is acutely connected to said housing and permits a circular flow of blood and gas-containing bubbles within said chamber so that the bubbles may concentrate at a central portion of said chamber.

8. The system of claim 2, wherein said valve means includes a float operating to said maximum open valve position in response to large accumulations of undissolved gas within said chamber and permits maximum flow of undissolved gas through said second outlet and said return means to said transfer means.

9. The system of claim 8, wherein said transfer means includes a constant displacement pumping means operating to reduce the pressure within said chamber in response to the supply of large accumulations of undissolved gas within said chamber and permitting blood to cease flow through said first outlet and preventing the flow of undissolved gas through said first outlet.

Description:
BACKGROUND OF THE INVENTION

This invention relates to a liquid-gas separator and specifically to a valve for controlling the flow of liquid and gas through a separator outlet. The liquid-gas separator of the present invention has particular usefulness when connected with a blood-gas separating system for corporeal perfusate circulation although the invention is not so limited.

Perfusate circulation to a human or animal during heart surgery or heart transplant operations requires extremely reliable apparatus for supplying and controlling the perfusate flow. Extreme care must be exercised to prevent undissolved oxygen or other gases flowing with the blood perfusate from entering the arterial system of the patient.

Oxygenator units are employed to impregnate a blood perfusate with oxygen and to remove carbon dioxide before submission to the patient. Under some conditions, the perfusate may contain up to 100,000 bubbles of oxygen and other gases per minute ranging in diameter up to 100 microns. Although gas bubbles smaller than the smallest capillary, or larger bubbles which find their way to an outer limb, may be tolerated with little or no apparent affect, a very small amount of gas supplied to a vital organ can cause severe malfunction of the organism and may result in death of the patient. Large amounts of gas (such as a liter or more, for example,) infused over a short period of time (such as a few minutes, for example) will invariably cause severe body malfunction and also possibly death. Such difficulties result because physiologic blood pressures are inadequate to force gas bubbles through the vascular system thus allowing the bubbles to act as restrictions or "plugs" to prevent perfusion to the affected areas.

SUMMARY OF THE INVENTION

This invention relates to a liquid-gas separating apparatus providing a valve for controlling the flow of liquid and gas through a separator outlet. Applicant's invention is particularly applicable to a blood-gas separating system for extra-corporeal perfusate circulation and provides a reliable and safe system for preventing undissolved gas from being supplied to a patient although the invention is not so limited.

In general, a liquid-gas separating apparatus provides a housing defining a chamber which includes a liquid and gas receiving inlet and a liquid outlet together with a second outlet located in the upper portion of the chamber. A valve member is located to be freely movable in all directions within the chamber and is responsive to the liquid and gas within the chamber to control the flow of liquid and gas through the second outlet. Specifically, the valve member operates to move between a maximum open position for permitting the essentially free flow of gas and possibly small amounts of liquid through the second outlet and a plurality of modulating positions including a position for maximum restriction of the second outlet for permitting a controlled flow of liquid and gas through the second outlet.

In one form of the invention, the valve means for the second outlet of the separator includes a valve seat located at the upper portion of the separating chamber at the entrance to the second outlet which provides three equally spaced projections to prevent the freely movable valve member from completely sealing the second outlet when assuming a position of maximum restriction. Alternatively, the valve seat may be constructed to provide one or more grooves. It is therefore apparent that the valve means permits a continuous purge or flow of liquid and gas under all operating conditions.

The freely movable valve member within the separating chamber may take many forms or shapes and applicant's preferred embodiment provides a spherical float which is freely movable in all directions within the separating chamber. The separator housing is designed to provide an upper portion having a chamber surface extending upward to the second outlet which is continuously curved such as in a concave or convex manner, for example, to permit free movement of the valve member to and from the modulating positions at the second outlet.

An alternative embodiment employs a freely movable spherical float having several ridges or projections which cooperate with the second outlet so that a controlled flow of liquid and gas is permitted at all times even though the valve member is in a position of maximum restriction.

The valve member of the invention preferably constitutes a float having a specific gravity which is approximately 95 percent of the specific gravity of the liquid to provide the proper modulation for the second outlet.

A separating means is connected between the inlet and the liquid outlet so that liquid and dissolved gas will be separated from any undissolved gas before passing through the second outlet. Applicant preferably utilizes a screen located in the lower portion of the separating chamber which is adapted to be submerged in liquid at all times to facilitate efficient separation. The screen may be formed of woven monofilament fibers such as nylon or the like and it is contemplated that many alternative separating elements could also be employed within applicant's invention.

The inlet to the separating chamber is preferably connected to the chamber at an angle to provide a circular or whirlpool type of liquid flow within the chamber. Such a circular type of flow tends to concentrate bubbles at a central portion of the chamber to facilitate separation by the separating means and further assist in the removal of the bubbles through the centrally located second outlet at the upper portion of the separating chamber.

In a system for separating blood and dissolved gas from undissolved gas for perfusate circulation, an oxygenator unit is provided to impregnate a blood perfusate received from a blood supply with oxygen. The oxygenated blood perfusate is conducted by a constant displacement type pump to the blood-gas separator wherein undissolved gas is separated from the blood perfusate before being supplied to a patient. The oxygenator unit and the constant displacement type pump thus constitutes a blood transfer unit for providing oxygenated blood to the blood-gas separator and various other types of transfer units may be employed within applicant's invention.

The second outlet of the blood-gas separator is connected to return blood and gas to the transfer unit thereby preventing undissolved gas from entering the blood perfusate outlet and into the patient.

The feedback connection from the second outlet of the separating chamber to the transfer unit may conveniently be made of plastic or other translucent material so that a continuous return flow of blood and dissolved gas visually indicates that a minimal undissolved gas condition exists within the separating chamber signifying a desirable operation.

The modulating effect of the freely movable valve member controls the amount of blood and gas permitted to return to the transfer unit while the continuous slow purge of blood under minimal undissolved gas conditions prevents accumulation of such gases over long periods of time. The valve means also operates between the modulating and fully opened positions for maintaining the separating means submerged in blood at all times.

In an abnormal operation of the system, the constant displacement type pump of the transfer unit permits a reduction in pressure within the separating chamber when large amounts of undissolved gas accumulates therein. Under such conditions, the valve means will fully open the second outlet to permit the free flow of undissolved gas to the transfer unit while blood perfusate flow through the first or perfusate outlet may cease and under some conditions even back flow into the chamber to absolutely prevent the flow of undissolved gas through the first outlet to the patient. The second outlet of the separating chamber is generally connected to a low pressure input of the transfer unit thereby providing the proper pressure control within the separating chamber.

Applicant thus provides a highly desirable liquid-gas separating system including a liquid-gas separating apparatus which may conveniently be made from a polyethylene material or the like which economically may be disposed of after a single use but which operates in a very efficient manner to eliminate undissolved gas from a liquid. Such system may be conveniently used for human or animal extra-corporeal perfusate circulation commonly utilized during surgery or the like although the invention is not so limited.

BRIEF DESCRIPTION OF THE DRAWING

The drawing furnished herewith illustrates the best mode presently contemplated by the inventor and clearly discloses the above advantages and features as well as others which will be readily understood from the detailed description thereof.

In the drawing:

FIG. 1 is a block diagrammatical flow chart illustrating a blood-gas separating system for perfusate circulation;

FIG. 2 is a diagrammatical illustration of a liquid-gas separating apparatus utilized in the separating system of FIG. 1;

FIG. 3 is a section taken along the lines 3-- 3 of FIG. 2; and

FIG. 4 is a diagrammatical illustration of an alternative embodiment of the valve member illustrated in FIG. 2.

The drawing illustrates a blood-gas separating apparatus which may be advantageously utilized within a system for extra-corporeal perfusate circulation for a patient. With reference to FIG. 1, an oxygenator unit 1 is connected to receive blood perfusate from a supply 2 and operates to add oxygen to be dissolved by the blood perfusate and to remove carbon dioxide by any one of a number of methods well known to those skilled in the art and further explanation thereof is deemed unnecessary.

The oxygenated blood perfusate is pumped by a constant displacement type pump 3 to a blood-gas separator 4 whereat undissolved gas is removed from the perfusate and returned through the line 5a to a low pressure input of the oxygenator 1. The separator 4 operates to supply blood free of undissolved gas to a patient for corporeal perfusate circulation. Under ideal conditions of perfusate flow, the separator 4 operates to recycle blood and dissolved gas through the line 5a for return to the oxygenator unit 1 as will be more fully described hereinafter.

FIG. 2 illustrates the blood-gas separator 4 which includes a housing 5 having an inner separating chamber 6 adapted to receive blood perfusate and undesirable undissolved gas from the pump 3 through an inlet 7. A blood perfusate outlet 8 is located at the lower portion 9 of chamber 6 and permits the flow of perfusate free of undissolved gas to a patient undergoing surgery.

A screen or filter 10 is positioned within the lower portion 9 of chamber 6 so that the blood perfusate must pass through screen 10 before exiting or passing through the outlet 8. Screen 10 may conveniently be made of woven monofilament fibers such as nylon which operates in a highly desirable manner when continuously submerged in blood to separate the undissolved gas from the blood perfusate. The screen 10 may, however, take other forms or be made of other materials and placed at other positions within chamber 6 while remaining within the scope of the invention.

Undissolved gas entering the inlet 7 is liberated by the screen 10 and rises to form a gas pocket at the upper portion 11 of the chamber 6. Such a pocket of gas together with the incoming blood perfusate thus forms a blood-gas interface 12 upon which bubbles 13 congregate.

A second outlet 14 is located at the upper portion of housing 5 and permits liberated gas together with portions of blood perfusate and dissolved gas to be returned through line 5a to the oxygenator unit 1. A valve means is provided for controlling the flow through the second outlet 14 and includes a valve member 15 which freely floats and is permitted to move in all directions within the separating chamber 6. In other words, the valve member 15 is permitted to freely move with respect to the second outlet 14 in response to the blood and gas within the chamber as defined by the blood-gas interface 12 to thereby control the flow through the second outlet 14.

In a preferred form of the invention as shown in FIGS. 2 and 3, the second outlet 14 includes a valve seat 16 having three equally spaced projections or struts 17 which extend from the housing 5 inwardly toward the upper portion 11 of chamber 6. The struts 17 thus cooperate with the freely floating valve member 15 when in a position for maximum restriction of the second outlet 14 to permit a continuous purge of blood and gas.

An alternative embodiment of valve member 15 is illustrated in FIG. 4 which shows a spherical floating member 18 provided with three intersecting circumferential ridges 19 which are adapted to operate in conjunction with a relatively smooth circumferential valve seat 16 to also permit a continuous purge of blood and gas when in a position of maximum restriction to the second outlet 14.

Another feature of applicant's invention includes the angular relationship existing between an entrance conduit 20 of inlet 7 and the housing 5. As shown in FIG. 3, the incoming blood perfusate enters the chamber 6 at an angle and circulates in a whirlpool type motion within chamber 6 as illustrated by arrows 21. The incoming bubbles 13 are thus concentrated centrally as illustrated in FIG. 2 to facilitate separation of the gas by screen 10 and removal through the centrally located second outlet 14.

The upper portion of housing 5 adjacent to the upper portion of chamber 11 includes a housing portion 22 having a convex chamber surface extending upward to the second outlet 14 which is joined with a housing portion 23 providing a concave housing surface also extending upward toward the second outlet 14. The housing portions 22 and 23 are specially formed to permit the free movement of the valve member 15 in all directions and prevents member 15 from being "hung up" by unnecessary obstructions, projections or the like. The inlet 7 and the second outlet 14 are generally constructed of a lesser diameter than the diameter of the spherical valve member 15.

Under an ideal operation, blood perfusate entering inlet 7 fails to contain undissolved gas thereby permitting the blood perfusate to completely fill chamber 6 and raise the freely movable valve member 15 to its uppermost position for providing a maximum restriction to outlet 14. Blood perfusate and dissolved gas, however, is permitted to flow through outlet 14 and return to oxygenator 1 through line 5a since the projections 17 prevent the valve member 15 from completely seating with seat 16 and sealing outlet 17. The utilization of a transparent tube for the line 5a through which the blood perfusate is permitted to return to the oxygenator unit 1 thus provides a visual indication of a desirable normal operation.

Small amounts of undissolved gas entering into chamber 6 through inlet 7 are continuously permitted to be purged through the second outlet 14 even though the freely movable valve member 15 assumes a maximum restrictive position. As greater amounts of undissolved gas enter the chamber 6, the freely movable valve member is permitted to descend in accordance with the varying level of the blood-gas interface 12 to assume any one of a number of modulating positions thus providing a varying restriction to the second outlet 14. Such modulation is effective for permitting controlled amounts of blood and gas to pass through the second outlet 14 while maintaining a desirable operating pressure within chamber 6 to permit the flow of blood perfusate through outlet 8.

The entry or accumulation of larger quantities of undissolved gas within chamber 6 permits the movable valve element 15 to descend to a position where the second outlet is completely unobstructed. Under such condition, a maximum amount of undissolved gas is permitted to flow through the second outlet 14 through line 5a to be returned to the oxygenator unit 1.

Under conditions where the separating chamber 6 experiences an excessively large accumulation of undissolved gas, the operation of the constant displacement pump 3 together with the valve means permits the pressure within chamber 6 to correspondingly decrease to a very low level. Under such conditions, the valve member 15 will fully open the second outlet 14 to permit the free flow of undissolved gas to the oxygenator unit 1 while blood perfusate flow through the outlet 8 may cease and under some conditions even back flow into chamber 6 to absolutely prevent undissolved gas from exiting through outlet 8 and into a patient. Applicant has found that the subject blood-gas separating system efficiently operates to continually prevent the interface 12 from dropping below the upper portion of screen 10 even under the most adverse operating conditions.

In a preferred embodiment, the system is constructed so that the line 5a will conduct approximately 100 cubic centimeters of blood perfusate and dissolved gas per minute under a pressure of 400 millimeters of mercury to the low pressure input of the oxygenator unit 1 when the valve member 15 assumes a maximum restrictive position with respect to outlet 14. In addition, the system is capable of bleeding undissolved gas through the second outlet 14 at a rate of approximately 7 liters per minute at a pressure of 60 millimeters of mercury when the valve member assumes a fully open position.

The present invention thus provides a highly desirable blood-gas separating system including a separating apparatus which is easy to manufacture form polyethylene or the like and may economically be replaced after a single use. The system thus provides a highly efficient and desirable gas separation from blood perfusate particularly desirable for extra-corporeal perfusate flow applications.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention: