WO1993001846A1

WO1993001846A1 - Integrated cardioplegia system

Info

Publication number: WO1993001846A1
Application number: PCT/US1992/004028
Authority: WO
Inventors: Alan R. Seacord
Original assignee: Daily, Pat, O.
Priority date: 1991-07-16
Filing date: 1992-05-14
Publication date: 1993-02-04

Abstract

An integrated cardioplegia system comprises an oxygenating chamber (24) including inlets (30, 34, 38) for introducing a quantity of blood and/or a cardioplegic fluid into said oxygenating chamber, inlets for introducing selective amounts of oxygen (58) and carbon dioxide into the blood and/or cardioplegic fluid in the oxygenating chamber, a filtered fluid chamber (26) and filters (50) in the housing for filtering fluids introduced into the filtered fluid chamber, a temperature regulating chamber (28), and a pump (70) and tubing (76) for circulating the fluid through the temperature regulating chamber for adjusting the temperature of the fluid and tubing (84, 88) for conveying the fluid to a patient.

Description

Integrated Cardioplegia System

Technical Field

The present invention relates to cardioplegia devices and pertains particularly to an improved integrated cardioplegia system for supplying of optimum cardioplegic solutions to the heart during surgical operations.

Background Art

It is desirable to reduce the metabolism of organs when they are being operated on in order to reduce the energy requirements thereof. If the energy requirements of the organ are sufficiently reduced during this time, damage to the organ can be reduced or eliminated. In cardiac surgery, for example, the heart is often deprived of blood for at least a short period of time. It is desirable that the energy requirements of the heart be as low as possible during this period of time. A desirable approach to reducing the energy requirements of the heart and other organs is to reduce the temperature of the organ.

The most common method of intraoperative preservation of the myocardium is cardioplegic arrest. An essential component of this method is hypothermia. Cardiac arrest with hypothermia has become the most common method of intraoperative preservation of the myocardium. It is preferable to reduce the temperature of the heart to about four degrees Centigrade during heart surgery.

It is also necessary to supply oxygenated blood and/or cardioplegic fluids to the heart during open heart surgery. It is desirable that the blood and fluids be cooled, preferably to about four degrees Centigrade, in order to provide optimum reduction in metabolism. These fluids must also be filtered and defoamed.

Several methods of cooling organs of the body during surgery have been developed. One of the desirable approaches is that of using a cooling jacket or pad, such as disclosed in U. S. Patent No. 4,154,245, entitled "Apparatus for Local Hypothermia", and incorporated herein by reference as though fully set forth.

Referring to Fig. 1 of the drawings, there is schematically illustrated an exemplary prior art cardioplegia system. The illustrated system comprises a reservoir 10 for supplying a cardioplegic fluid.

The reservoir is typically a roller pump 12 which forces the fluid through a tubing circuit, which includes cooling means such as a refrigerant unit 14 with heat exchanger 16 or sometimes an ice bucket.

The fluid is supplied to a heart 18 as an overspray or through a cooling pad or blanket, and may be recirculated.

Accordingly, it is desirable that improved cardioplegia system be available.

Disclosure of the Invention

It is the primary object of the present invention to provide an improved integrated cardioplegia system that is easy to set up and use.

An integrated cardioplegia system comprises an oxygenating chamber including inlets for introducing a quantity of blood and/or a cardioplegic fluid into said oxygenating chamber, inlets for introducing selective amounts of oxygen and carbon dioxide into the blood and/or cardioplegic fluid in the oxygenating chamber, a filtered fluid chamber and filters in said housing for filtering fluids introduced into the filtered fluid chamber, a temperature regulating chamber, and a pump and tubing for circulating the fluid through the temperature regulating chamber for adjusting the temperature of the fluid means for conveying the fluid to a patient.

Brief Description of Drawings

The above and other objects and advantages of the present invention will become apparent from the following description when read in conjunction with the drawings wherein:

Fig. 1 is a schematic illustration of a prior art system;

Fig. 2 is a schematic illustration of a system in accordance with a preferred embodiment of the invention;

Fig. 3 is a side elevation view, partially in section, of a preferred embodiment of the Fig. 2 system housing construction;

Fig. 4 is a front elevation view, partially in ^■ section, of a preferred embodiment of the system housing construction;

Fig. 5 is a bottom plan view of the embodiment of Fig. 3 showing the cooling coil arrangement; and

Fig. 6 is a front elevation view, partially in section, of an alternate embodiment of the system housing construction. Best Mode for Carrying Out the Invention

Referring to Fig. 2 of the drawing, a system in accordance with the preferred embodiment of the present invention is illustrated. The system, designated generally by the numeral 20, comprises a housing 22, and is divided by suitable partitions to provide or define a plurality of at least two reservoirs 24 and 26 and possibly a third reservoir 28. The reservoirs are preferably disposed in a vertical arrangement as illustrated, with the first or top reservoir 24 being an oxygenating reservoir, the second reservoir 26 being an oxygenated and filtered blood holding reservoir, and the third reservoir 28 being a thermal or cooling reservoir. The cooling reservoir 28 may alternately be integral with the primary housing 22 or be a separate housing as will be discussed.

The oxygenating reservoir 24 is provided with a blood inlet port 30 for introducing blood from a source 32, a cardioplegic fluid inlet 34 for introducing a cardioplegic fluid, such as a saline solution from a reservoir 36, and a quick prime port 38 for supplying a priming fluid from a suitable source 40 directly through the filter into the holding reservoir 26. Return ports 42 and 44 are provided in the chamber 24 for return of recirculated fluid. As illustrated in Fig. 2, the oxygenating chamber 24 is provided with a centrally disposed overflow port 46, which comprises an upstanding open tube extending upward from a partition wall 48, and defines an overflow port for conveying fluid from the oxygenating chamber 24 into the holding chamber 24 by way of a filter 50 disposed in the top of the reservoir 26. An oxygenating membrane 52 separates the oxygenating reservoir 24 into an oxygen chamber 54 and a liquid chamber 56 in the upper part of the reservoir 24. An oxygenating port 58 opens into the oxygen or gas chamber 54 for introducing a gas such as oxygen and/or CO„ from a source 60. Oxygen introduced from this source 60 via port 58 into the chamber 54 passes through the filter or membrane 52 into the liquid 56 disposed within the chamber 56. The port 46 and the vertical conduit thereof establishes a minimum level of liquid within the chamber or reservoir 24. Liquid above this level spills over via port 46 and through filter 50 into the holding reservoir 26. A sample port 62 is provided in the holding reservoir 26 for obtaining samples for hematocrit and other blood assays.

An outlet port 64 conducts fluid from the reservoir 26 by way of a tube 66 via a Y connector 68 to a roller pump 70, and therefrom by way of a tube 72 to an inlet 74 to coils 76 of the heat exchanger. The fluid exits the heat exchanger by way of port 78, where it is then supplied by way of a tubing or line 80 and a Y coupling 82 and via tubing 84 by way of a Y coupling 86, and to a tubing 88 for supply directly to the patient and by way of a tube 90 to a cooling jacket 92.

Return fluid from the cooling jacket 92 passes by way of tubing 94 and a Y coupling 96, either by way of a bypass or recirculating tubing 98 or a line 100 to either the pump 70 or back to the oxygenating reservoir 24.

Cardioplegic fluid passed through the cooling or thermal control reservoir 28 may also be recirculated by way of a recirculating tube 102 back to the recirculating port 42 of the oxygenating chamber 24. Flow in the various tubes of the circulating system may be controlled by a number of clamps, such as clamp 104 in the cardioplegic pump inlet line 66, clamp 106 in the supply line 84, and clamps 108 and 110 in the patient lines 88 and the cooling jacket lines 90. Return fluid from the cooling jacket 92 may be controllably passed along tubing 98 and 100 by means of clamps 112 and 114. A clamp 116 controls the fluid along recirculating tube or line 102. Similar clamps 118, 120 and 122 may be used to control the supply of fluids from reservoirs 32, 36 and 40.

Referring to Figs. 3 and 4, a preferred construction of the housing is illustrated. As illustrated, the housing is preferably constructed of multiple unit modular tower construction.

Referring to Figs. 3 and 4, a preferred construction of the housing of the system is illustrated. As illustrated, the housing is preferably constructed of a multiple unit modular tower-like construction. This involves construction of separate portions of the housing and connecting them together in a vertical tower-like arrangement. In the preferred construction, the housing comprises severable lower housing 126 and upper housing 128.

The lower housing preferably serves as the cooling unit and, in a preferred embodiment, is separable from the upper housing unit but may serve as a supporting stand therefore. The lower housing is constructed of a generally rectangular box-like construction having front, back and opposing side walls, with a backwall 132 and sidewalls 134 and 136 having a downwardly depending portion forming a generally ϋ-shaped base support. A bottom of the housing chamber is formed by a bottom or lower wall 138 that is curved, and has upwardly extending separating partitions 140 and 142 that serve to cooperate with a top cover 144 having downwardly extended walls 146 and 148 that serve to form flow channels within the cooling housing. A partial separation wall, as shown in Fig. 5, partially separates the cooling chamber laterally as shown in Figs. 3 and 5. These walls form channel ways for the flow of coolant from the inlets and outlets 152 and 154.

Cooling coils for passage of cardioplegia fluid through the cooling chamber 156 extends from an inlet 158 to an outlet 160. Coupling nipples or connectors 162 and 164 are provided for connecting to the supply lines or hoses 72 and 80, as shown in Fig. 2. The couplings such as 162, for example, have a tap port 166 which normally is closed by a threaded cap or the like for the insertion of temperature monitoring sensors thermometers or the like.

The housing 126 and cap 144 are separately formed, such as by molding or the like, then assembled after the insertion of the cooling coil 156 and after sealed or bonded together in a suitable fashion, such as by means of welding or other suitable bonding means.

The upper housing 128 comprises a similar rectangular box-like housing formed at its base to fit within the upwardly extending peripheral rim of the top 144. The upper housing 128 has the usual upstanding four rectangular walls extending upward from a sloping base or floor 168 forming an oxygenated and filtered blood reservoir. At the bottom of the housing, sample port 62 and outlet or blood supply port 64 are provided. A suitable coupling or connection nipple 170 may be provided for each of the ports 62 and 64.

The housing 128 is normally constructed with an open top in which a blood filter retainer or mounting unit 172 is mounted. The filter mounting or retaining unit 172 comprises substantially cap-like unit having a peripheral flange 174 engaging the upper end of the housing 128, with an inwardly directed wall 176 extending inward, and a rectangular box-like cavity formed by downwardly depending walls forming a filter cavity. A plurality of fingers 180 extending outward from a common hub 182 to the downwardly depending walls extend across the lower end of the filter cavity for retaining a pair of filters 184 and 186 in place. The blood filter mounting assembly 172 includes upwardly extending walls 188 on which is mounted a cap 190 having a central port 200. Mounted above the tap 198 is a wall construction comprising a central partition 202, with downwardly depending peripheral walls 204 and upwardly extending walls 206 forming a lower chamber 208 and an upper chamber 210. A vertically extending tube 212 extends above wall 202 and below wall 202 through port 200 and into the lower filter housing 172. Oxygen inlet port 58 communicates with chamber 208, and provides oxygen for blood and cardioplegia introduced into the chamber 210 by way of ports 42 and 34. Inlet port 38 connects with a source of cardioplegia fluid for a quick prime by communicating directly with tube 212 directly through the filters 184 and 186 directly into the blood cardioplegia chamber of housing 128.

A cover cap 214 covers the upper end of the housing member 206 and forms inner chamber 210. The components of the upper housing 128 are secured and sealed together to form a closed unit as described above. The upper unit may be mounted on top of the lower housing 126 as previously described or may be positioned remotely therefrom. The cooling unit 126 preferably separates from the upper housing so that it may be easily positioned adjacent the patient to minimize cooling losses.

Although the system may be constructed of any number of suitable materials, the housing will preferably be formed of a polycarbonate, tinted to a liquid purple hue. After sterilization, the housing will be clear to allow easy visualization of graduations thereon. Total volume of the reservoir will be about twenty-five hundred milliliters. A ten percent overage capacity will be implemented into the system (2750 milliliters) . The design of the reservoir is such that a membrane oxygenerator system can be incorporated into the system. The heat exchanger housing may preferably be separate and detachable from the main housing 22, but preferably attachable thereto in a supporting position as illustrated. This construction enables the heat exchanger to be positioned adjacent the patient remote from the remainder of the system. It also enables the heat exchanger to be on the patient side of the pump, thus isolating a source of heat.

The heat exchanger tubing may preferably be of a plastic tubing such as PVC for disposability. However, aluminum or stainless steel would be a preferable construction for reusable units in that it would normally provide better heat transfer. The tubing is preferably arranged with several passes along the height of the chamber as illustrated in Figs. 3-5. This provides large cooling surface area for contact by the blood and cardioplegia fluids.

The heat exchange unit may utilize any suitable cooling fluid, but preferably has a refrigeration unit 122 circulating a coolant through the heat exchange chamber 28 by way of suitable conduits or lines 124 and 126.

Referring to Fig. 6, an alternated embodiment is illustrated wherein the filtered fluid chamber and heat transfer chamber are combined as one. In this embodiment, a lower housing 220 is permanently secured directly to the upper housing and becomes integral therewith. The housing 220 forms a chamber 222 in which is disposed cooling coils 224 through which a coolant passes via an inlet port 226 and outlet port

228. The cardioplegia fluids pass over the coils for cooling and is drawn out via an outlet port 230. The oxygenated fluid passes directly through the filters into the combined filtered fluid chamber and heat transfer chamber 222. This construction has the advantage of simplicity. However, it has the disadvantage of placing the pump between the temperature regulating unit and the patient.

The present system provides a number of advantages over prior art approaches, including ease of setup and operation without undue attention. The system provides a more uniform control over the temperature of the cardioplegic fluid, and thus the overall temperature control over the operation. The system provides means for mixing blood and cardioplegic fluid at any ratio desired. The system requires only one pump head to provide supply of the fluid for profusion, heart or organ overspray or for cooling pad use. The system is integrated and thus decreases the amount of monitoring required as well as the time required for setup and breakdown. This system can use less blood and fluid to prime and maintain the system. When through infusing, the flow can be clamped off and supplied for topical cooling.

While I have illustrated and described my invention by means of specific embodiments, it is to be understood that numerous changes and modifications may be made therein without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. An integrated cardioplegia system including multiple chamber housing means for providing a continuous supply of a cardioplegia fluid, comprising: an oxygenating chamber including means of introducing oxygen therein; first inlet means for introducing a quantity of a cardioplegic fluid into said oxygenating chamber; means for maintaining a predetermined level of said fluid in said oxygenating chamber; means for introducing selective amounts of oxygen and carbon dioxide into said cardioplegic fluid in said oxygenating chamber; a filtered fluid chamber in said housing; fluid transfer means for transferring fluid from said oxygenating chamber into said filtered fluid chamber; filter means in said fluid transfer means for filtering fluids introduced into said filtered fluid chamber; a temperature regulating chamber; means for circulating said fluid through said temperature regulating chamber for adjusting the temperature of said fluid; and means for conveying said fluid to a patient.

2. A cardioplegia system according to claim 1 wherein: said oxygenating chamber is disposed above said filtered fluid chamber; and said means for transferring fluid from said oxygenating chamber into said filtered fluid chamber comprises an overflow port.

3. A flexible thermal pad according to claim 1 further comprising a blood inlet port for selectively introducing blood into said oxygenating chamber.

4. A cardioplegia system according to claim 1 wherein said fluid transfer means for transferring fluid from said oxygenating chamber into said filtered fluid chamber comprises a conduit extending from said oxygenating chamber to the inlet side of said filter.

5. A cardioplegia system according to claim 4 wherein said means for maintaining a predetermined level of said fluid in said oxygenating chamber comprises an extension of said conduit into said oxygenating chamber to said predetermined level.

6. A cardioplegia system according to claim 5 further comprising a quick prime port for introducing fluid directly into said filtered fluid chamber.

7. A cardioplegia system according to claim 6 wherein said quick prime port is disposed directly above said overflow port.

8. A cardioplegia system according to claim 1 including fluid circulating means comprising: a roller pump having an inlet port and an outlet port; tubing means for connecting said filter reservoir to said inlet port; tubing means for connecting said outlet port to said thermal chamber; and tubing means for connecting an outlet from said thermal chamber fluids to a patient.

9. A cardioplegia system according to claim 8 wherein said housing means comprises separable first and second housings, and said thermal regulating chamber is disposed alone in one of said housings for remote positioning relative to the other of said housings.

10. A cardioplegia system according to claim 1 wherein: said oxygenating chamber is disposed above said filtered fluid chamber; and said means for transferring fluid from said oxygenating chamber into said filtered fluid chamber comprises a conduit extending from said oxygenating chamber into an inlet side of said filter.

11. A cardioplegia system according to claim 10 wherein said housing means is separable into separate upper and lower housings, and said thermal regulating chamber is disposed in said lower housing for remote positioning relative to said upper housing.

12. A cardioplegia system according to claim 1 wherein said housing means is of a unitary tower construction, and said temperature regulating chamber and said filtered fluid chamber is a common chamber.

13. An integrated cardioplegia system having ultiple chamber housing means for oxygenating and cooling cardioplegia fluids comprising: aann oxygenating chamber within said housing; inlet means for introducing a quantity of blood from at least one source to said oxygenating chamber; means for introducing a fluid into said oxygenating chamber; means for maintaining a predetermined level of said fluids in said first chamber; means for introducing selective amounts of oxygen and carbon dioxide into said fluid in said chamber; a filtered fluid chamber in said housing; means for transferring fluid from said oxygenating chamber into said filtered fluid chamber; filter means in said housing between said oxygenating chamber and said filtered fluid chamber for filtering fluids introduced therein; a temperature regulating means in said housing; means for circulating said fluid through said temperature regulating means for adjusting the temperature of said fluid; and means for conveying said fluid to a patient.

14. A cardioplegia system according to claim 13 wherein: said oxygenating chamber is disposed above said filtered fluid chamber; and said means for transferring fluid from said oxygenating chamber into said filtered fluid chamber comprises a conduit extending from said oxygenating chamber to the inlet side of said filter and defining an overflow port.

15. A cardioplegia system according to claim 14 further comprising a quick prime port for introducing fluid directly into said filtered fluid chamber.

16. A cardioplegia system according to claim 15 wherein said quick prime port is disposed directly above said overflow port.

17. A cardioplegia system according to claim 16 including fluid circulating means comprising: a roller pump having an inlet port and an outlet port; tubing means for connecting said filter reservoir to said inlet port; tubing means for connecting said outlet port to said thermal chamber; and tubing means for connecting an outlet from said thermal chamber fluids to a patient.

18. A cardioplegia system according to claim 17 wherein said housing means is of a unitary tower construction, and said temperature regulating chamber and said filtered fluid chamber is a common chamber.

19. A cardioplegia system according to claim 17 wherein said housing means is separable into separate upper and lower housings, and said thermal regulating chamber is disposed in said lower housing for remote positioning relative to said upper housing.

20. An integrated cardioplegia system having multiple chamber housing means for oxygenating and cooling cardioplegia fluids comprising: an oxygenating chamber within said housing; inlet means for introducing a quantity of blood from at least one source to said oxygenating chamber; means for introducing a fluid into said oxygenating chamber; means for introducing selective amounts of oxygen and carbon dioxide into said fluid in said chamber; a filtered fluid chamber disposed directly below said oxygenating chamber in said housing; means for maintaining a predetermined level of said fluids in said oxygenating chamber and for transferring fluid from said oxygenating chamber into said filtered fluid chamber; filter means in said housing between said oxygenating chamber and said filtered fluid chamber for filtering fluids introduced therein; a temperature regulating chamber in said housing wherein said housing means is separable into separate upper and lower housings, and said temperature regulating chamber is disposed in said lower housing for remote positioning relative to said upper housing; fluid circulating means comprising a roller pump having an inlet port and an outlet port, and tubing means for connecting said filter chamber to said inlet port, tubing means for connecting said outlet port to said temperature regulating chamber, and tubing means for connecting an outlet from said thermal chamber for conveying said fluid to a patient.