CA2938639A1 - Heat exchange system for patient temperature control with multiple coolant chambers for multiple heat exchange modalities - Google Patents

Abstract

Cold plates (30, 32) through which refrigerant flows define a slot (34) between them that can receive a cassette (50) through which sterile working fluid with a relatively low flow rate flows from an intravascular heat exchange catheter (12). The working fluid from the catheter (12) is heated or cooled by heat exchange with the cold plates (30, 32) through the walls of the cassette (50) to maintain the sterility of the working fluid. On the other hand, high flow rate working fluid chambers surround the cold plates (30, 32) and non-sterile working fluid from an external heat exchange pad (14) flows through the high flow rate working fluid chambers to exchange heat through direct contact with the cold plates (30, 32).

Description

HEAT EXCHANGE SYSTEM FOR PATIENT TEMPERATURE
CONTROL WITH MULTIPLE COOLANT CHAMBERS FOR MULTIPLE HEAT
EXCHANGE MODALITIES
L FIELD OF THE INVENTION
The present application relines generally to heat exchange Systems for patient temperature control with multiple coolant chambers for multiple heat exchatigv modal4ies, H. BACKGROUND OF THE INVENTION
Patient temperature control systems have been introduced te prevent fever in patients in the mum IC13 dile to suffering from sub-atachnoid hemorrhage OT other neurologic malady such as stroke: Also, such systems have been used to induce mild or moderate hypothermia to immve the outcomes of patients suffering from such maladies as stroke, cardiac arrest, .myocardial. Watch* ttauitatic brain injury, and high intracranial pressure.
Examples of travaSculair heat exchange catheters are disclosed in U.S. Patent Nos.
6,419,643, 6,416,533, 6;409,747, 6,405,080, 6,393,320, 0,308,304, 6,338,727, 6,299,599, 6,290,71,7, 6,287,326, 6,165,207, 6,149,670, 0,146,411, 6;126,684, 6;306,161, 6,264,679, 623 6,149,676 6,149,673, 6310,168, 5,989,238, 5,879,329, 5,837;003, 6,383;210, 6,379,378, 6,364,899;
6;325,818, 6,312,452, 6,201,312, 0,254,626, 6,251,130, 6,251,129, 6,245,095, 6,238,428, 6,235,0485 6,231,595, 6,224,624, 6,149,677, 6,096,068, 5,042,559, all of which are incorporated herein by reference.
External pad eat temperature control systems may be used. Such systems am disclosed in LLS, Patent Nos 6,827,728, 6,818,012, 6,802,855, 0,799,063, 6,764,391, 6,692,518., 6,609,715, 6,660,027, 6,648,905, 6,645,232, 6,620,187, 6,461,379, 6,375,674, 6,197,045, and 6,1.88931) (collectively,. Ihe extenual pad patents"), all of which are:
incorporated herein by reference;
In the present assignee's USPN 7O70,6 12, also incorporated herein by reference, a heat exchange console that could receive the coils of working fluid loops of both an intravaseular he* exchange catheter and an e.wiTial heat exchange pad was docribed and patented, In general, in all of the intravaScidar and external patient 'temperature control solutions, the temperature of the working fluid flowing through the catheter or pad is regulated by a heat exchange console based on :feedback provided by the patient's actual body temperature, typically core body temperature as may be variously measurtxl rectally, csophageally, tympanic eat temperature, blood temperature in. e.gõ the vciui cava, etc. The.
working fluid temperature is regulated by thermally coupling the working fluid to heating anctior cooling elements in the console.
SUMMARY OF THE INVENTION
AS understood herein, the working fluid of external pads, unlike that of intravaseular catheters, may not be required to be sterile. Furthermore, as understood herein, the working fluid flow rate of external pads may be significantly greater than the flow rates of sterile working fluid through intravascular catheters. With these recognitions in mind, in some applications: it may be desirable to use the same, heat exchanger with both a catheter and a pad but twO different working fluid pathways within the heat exchanger' With respective different characteristics tailored to their respective heat exchange modalities (intemil intravascular heat exchange with the blood using a catheter and=external heat exchange through the skin using a pad):

2 As used herein, unless otherwise specifically delimited by claim language, "pad"
means any device configured fOr placement against a .pitti exit s skin through which a work lug fluidalse referred to herein 6s a "coOlant" regardless of whether ternovim:t or adding heat.t the patient, can flow to exchange heat with a huinan patient A heat exchanger includes at least .first and second heat exchange plate assemblies defining a first modality work* lipid chamber between them. The first modality working fluid chamber is configured fr.$r toceiving a holder through Ulna Sterile wOrking fluid can flow to and from a first modality patient heat exchange =member Such that the Sterile working fluid can exchange heat with the plate assemblies through the holder without the stteile working fluid touching the plate assemblies. At least 4 Sepood modality working fluid chamber is defined M the beg exchanger through which second working fluid can flow to and from a smind modality patient heat exchange member such that the second working fluid from the second modality patient heat exchango member can exchange heat with at least one of the plate assettiblies by directly contacting the at least:one the plate assemblies.
The first modality patient heat exchange member can he estabilithed by an =intravascidar heat exchange catheter, and the heat exchanger may include the first Modality patient heat exchange member, On the other hand, the second modal iv patient heat exchange member can be established by an externally-applied exehange pad, and the system can include the pad. The second working fluid from the:second modality, patient heat exchange member need net be :sterile.
In seine :ekamples, the second modality working fluid chamber includes a fitst s:ab-ehamber in the lint plate assembly and a second sub-Chamber in the gmond plate assent*.
Each plate assembly can include at least one=respective refrigerant passageway through which.

3 refrigerant can flow to heat or cool the respective plate as,sembly. In example embodiments, refrigerant must flOW in series through the refrigerant passagewayS such Mat refrigerant must now first through the refrigemnt passageway of the first plate assembly before flowing through the refrigerant passageway of the second plate assembly. In other examples, refrigerant flows in parallel through the refrigerant chambers. in contrast, in eXaMple embodiments the second working fluid must flow in pafallel through the first and second subchambers. Or, the second working fluid may flow in series through the first and second subchambers.
in another aspect, a system has at least firstand second plate assemblies through which refrigerant can flow through respeotive fast and seCOnd refrigenint Chambers.
The plate assemblies define a slot between them that can receive first working fluid from an intravascular heat exchange catheter, so that the first working fluid from the catheter can. be heated or :cooled by the refrigerant flowing throngh the refrigerant chigribers The plate assemblies further include respective first and second working :fluid chambers laterally outbOard the respective .fiftt and second refrigerant chambers: and configured fel receiVing second working fluid from ati external heat exchange pad to facilitate heat exchange between the second working fluid and the refrigerant;
In another aspect; a system Mei udes a first plate and a first working fluid chamber on a first side of the first PIM, A fit* refrigeOnt:chatnber is On a second side of the first plate opposite the fag side, such that heat exChango 118: facilitated throitigh the first plate between the first refrigerant chamber and the first working fluid :chamber. A second winking fluid chamber is separated from: the first refrigerant ehamberby a wall through vsthich heat u:change may be effected between the second working fluid chamber and the first refrigemnt chamber,

4 The detnils of the present invention, both as to its structure and operation, can best be understood in reference to the Odeompamying drawings, in will ich like reference numerals refer to like parts, and in which:
BRIEF DESCRIPTION OF' TILE DRAWINGS
Figttro 1 is a schematic View of a nen-limiting system in accordance with the present invention;
Figure 2 is a perspective. view of an example working fluid cassette holder portion of a heat exchange system;
Figure 3 is a perspective view of one half of the cassette holder ShoWit in Figure 2, with the opaque metal inner surface shown in transpaiency to reveal the serpentine refrigerant passageway;
Figure 4 is 4 perspective view of an example working fluid cassette configured to engage the cassette holder shown in Figures 2 and 3;
Figure 5 is a cross-sectional view as seen along the line 5-5 M Figure 2; and Figure 6s a ctosssectiona I view of an alternate embodiment as would be seen along I e line 5-5 in Figure 2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring initially to Figure ,in accordance With present principles, a system .10 may include an intravascular heat exchange catheter 12 controlled by .a control system 14 to control patient temperature, ell., to prevent the patient 16 from becoming, febrile or to induce therapeutic hypothermia in the patient 16. In the catheter, working fluid t'alsn referteti to as "Coolant") such as hut not lint ited to saline circulates (typically under the influence of a pump "P" in the control system) in a closed loop from the control system 14, through a fluid supply line LI, through the catheter 12, and back to the:system 14 through a fluid return line 1,2, such that no coolant enters the body While certain preferred catheters are disclosed below, it is to be understood that other catheters can be used. in accordance with present principles, including, without limitationõ Any of the catheters disclosed above or in the following V.8.
patents, all incorporated herein by reference: 1...,1$PN 5,486,208, 5,837,003, 6,110,168, 6,149,673, 6,149,676, 6,231,594, 6,264,679, 6,306,161, 6,235,048, 6,238,428, 6,245,095, 6,251,129, 6,251,130, 6,254,626, 6,261312, 6;312,452, 6;325,818, 6,409,747, 6368,304, 6,338,727, 6,299,599, 6,287,326, 6,126,684, The catheter 12 may be placed in the venous system, esg., in the superior or inferior Vero cava.
Instead of or in addition to the catheter 12, the syStem 10 may include one or More pads 18 that are positioned against the external skin oldie patient 16 Only one pad 18 shown for clarity). The pad 18 may be, without limitation any one of the pads disclosed in the external pad patents. The temperature of the pad 18 can he 0000110 hy the colitrof system 14 to exchange heat with the patient 16, including to induce therapeutic mild or moderate hypothermia in the patient in response to the patient presenting with, e.g>, cardiac arrest, myocardial infarction, stroke, high intracranial pressure, traumatic brain injury, or other malady the effects of which can be ameliorated by hypothermia. The pad 18 may receive working fluid Brom the system 14 through a fluid Supply line L3, and return working fluid to the system 14 through a fluid return line L4.
The control system 14 may include one or more microprocessors 20 receiving target and patient temperatures as input and controlling, among other things, the pump "P" and a refrigerant compressor 22 with a bypaSS valve: 24 that cm be opened to permit refrigerant to:
bas the compressor The refrigerant circulates through a heat exchanger Within the control system 14 and described further .below:
Indeed and t1OW referring to Figure 2õ a portion of an example heat exchanger in the control systeM 14 is &hewn which includes at least two Cold plates 30, 32 defining a CagSettt Slot 34 between them .none embodiment, the width "W" of the slOt 34 is less than forty mils (0.040"), and may be between twenty nine mils and thirty One mils (0.029W3 n.
In a specific example the width "W" may be thirty mils. As fiirther detailed below, the slot 34 may establish a coolant chamber to receive a heat exchange member such as but not limited to a cassette. through Which 'working fluid from .111 intravaseular heat exchange catheter flows.
Because heat exchange is effected through the walls of the heat :exchange member, the working iTtuid from the catheter does not contact any surface or fluid in the heat exchanger of the control system 14 outside the walls of the heat exchange member. In this way, the working fluid, typically saline in non-limiting exarnples.,eirculating through the intrayasettlar catheter can remain Sterile. A.ccordinkly, attention will first focus on the coolant chamber established by the slot 34.
The cold plates 30, 32 may be made of metal, and can be rectilinear as shown and indeed may be nearly square. The cold plates 30, 32 may abut each other along left and right side walls 36, with elongated vertical cassette frame receptacles RI and R2 being located immediately inboard of the respective side walls 36 and With the SiOt 34 extending between the walls 36 and terminating at the rmeptaeles RI. R2 as Shown. The frame receptacles RI, R2 may be wider than the slot 3&

In the eX:ampie shown, refrigerant inlet and outlet tubes 3$, 4fl extend through at least one of the cold plates 32 to communicate refrigerant from a compressor into a refrigerant passageway in the cold plate which establishes a second coolant chamber in addition to (and in thermal contact with) the first coolant chamber established by the slot $4, Each cold plate may have its QW11 refrigerant inlet and outlet tubes, or, in the embodiment shown, only one cold plate may be formed with refrigerant inlet and outlet tubes and the other cold plate either thermally coupled to the cold plate in which the refrigerant flows andior receiving refrigerant from the other cold plate through passageways ibrrned through one or both of the side walls 36:
In one exatriple, pad working fluid inlet and outlets NIand P,õi may also be formed in at least one of the cold plates as: shown. As discussed in greater detail below, working fluid from the pad 18 via lines .13 arid IA may be potted into the pad working:
fluid inlet and outlets Pu and Pout to exchange heat with the refrigerant flowing through the cold plates. Also, to provide for wanting Working fluid, one or mom electric beaters 41 may be Mounted on One Or both. of the: cold plates to heat the cold plates. Alternatively to warm the cold PhitoS, the bypass valve 24 (Figure 1) may be opened to allow hot gaseous refrigerant from the compressor to bypass the condenser as the gaseous refrigerant circulates through the system:
Figure 3 Shows details of an example cold plate 32 looking at the inner surface in:
transparency; it being understood that the inner surface typically is Metal and that the serpentine refrigerant passageway 42 shown in Figure 3 typically would not be visible to: the human eye. In any case, the example refrigerant passageway that fluidly connects the refrigerantinlet 38 to the refrigerant outlet 40 may be serpentine-shaped as shown, or may be some other shape or pattern such as a herringbone pattern a wave pattern, etc.

Figure .4 shows .an example working fluid .pssette 50acording to: present principles.
The cassette.50 is configured:10 fit siingly into the slot 34 and cassette frame receptacles R
R2 defined between the cold plates .30, .32. Working fluid such as: saline from a patient-ngagable heat exchangemember such as the catheter 12 flows through the cassette 50 in operation, with the wolf:jag fluid exchanging heat with the refrigerant in the cold plates, In example embodiments, the cassette 50 is a low cost single-use disposable. item :that can contain, e.g., sterile Wine which circulates through. the catheter '12.. The cassette may be:
placed by a medical caregiver in. the slot 34 between the cold plates 30, .32 and the membrane portion which defines a space or working fluid chamber through w.bich. the example saline flows inflates when the working fluid flo),Vs through it, achieving thermal .contact with the cold plates 30, 32.
In the exampleShown, the cassette 50 includes a. frame .5.2 defining a periphety and a preferably rectilinear opening bounded as sho \yr' atleastthree sides by diepetiphety of the frame. In the non-Ihniting example shown, the frame includes an elongated prolleivipml-Aapixl 'Op rail 5.3 and elongatedparalielepiped-shaped left andright side rails 54 parallel to.
each other and perpendicular to the top rail 32. The. example frame 52 may have a metal strip or bc.ittom rail 51 opposite the top rail and connected to:the left andeight side rails to. support the 'membrane arid 'facilitate placing the membrane in biaxial tension. In any case,. the :eXample .frame 52 is rectilinear and is eonfigured for being. elbsely received between the two cold plates 30,32, with the side rails 54 slidably.engageable with. the frame receptaeles R I, R2 between the cold Plates 30, 32 and with the below-described membrane .assembly passed through theslot 36 to be in close jnxtaposition withthe refrigerant channels in =.the. cold plates.

In Figure 4, the frame, in the example shown, the tOp rail 53 thereof, is formed with a fluid inlet 56 in which an inlet tube 58 has been disposed and a fluid oti,tlet 60 in which an outlet tube 62 has been disposed, Both the inlet and outlet establish respective fluid passageveays through the frame into the opening, The inlet and outlet tubes 58, 62 may he engaged With the fluid return and supply lines LI. L2 that are aSsociated With the catheter 12.
The tubes 58, 62 may terminate at just below the top rail 53 (Figure 4), or they may extend any desired length down to. the bottom of the assembly, ix., the tubes 58.62 may extend almost the entire length of the left and right side rails= 54, ending just =above the below-deseribed bOnont scan of the membrane assembly.
Indeed, a polymeric, methlarane assembly 64.is Connected to the frame 52, blocking the opening that is bounded on four sides by the frame as shown. 'The membrane assembly includes a first membrane 66 that is parallel to and closely spaced from a second membrane 08, leaving a space=therebetween which establishes a working fluid chtunber;
The fluid inlet 56 and fluid outlet 60 communicate with the space between the membranes 66, 68, At least on and preferably both of the membranes 66,68 are disposed in =tension in the opening. The space between the membranes is expandable when filled with working fluid.
In one example, each membrane is no more than two mils (0.002) thick and more prderably is between one mil and two mils in thickness (0,001"-0.002"), inclusive. The exampie preferred membranes 66, 68 are co-extensive=with:the opening and like the opening:
are more.: or less :square, with the length of top and bottom edges of the example membranes being approximately equal (within + 10% and more preferably within 5%) of the lengths of the left and right edges of the membranes. In other embodiments instead of a square (1:1) aSpect ratio, an aspect ratio of up to I 1.,5 may be used. The working fluid chamber between the mei:Orates is also rectilinear and in the preferred embodiment no obstructions exist between the inembraties,rneaning the working fluid .thamber is a complete rectilinear, more or less square chamber, Owing to the thinness of the membranes66,. 68 and the closeness of the ce1dp1ates.30, n to each other and to themembrane. assembly between them when the cassette is engaged with the cold plates, the system shown in the figures affords low impedance of heat transfer between the refrigerant circulating in the cold plates and the working fluid circulating between themembranes 66, 68. The working fluid chamber between the, membranes inflates due to.
bac.kpressuregenerated by worldng fluid flow, eliminating or redwing theneed for a moving mechanism in the cold plates. Moreover, the narrow slot 34 between the two told plates.
provides better neat-transfer by reducing the coriduetiYe path length between thecold plates and the working fluid. The frame allows for ease of handling, such as insertion and removal of the cassette: with/from the cold plates.
With respect to the example. working fluid chamber between the membranes 66, 6$
having a. width-to-length aspect. ratio neat 1:1 (i.e., square or nearly So), the :amount of backpressure requiml to induce working fluid flow through heat exchanger is reduced comp.ared to a less square configuration. This minces the amount of work that a working fluid pump. must perform, .Which is desirable for two masons. One, since the pump may be di sposableõ.lower petfOrnandereqUitetnents translate into a lower costdisposable and quieter system. For instance, peristaltic roller pumps offer quiet operaticin and a.
low-cost disposable element, hut operatemost efficiently when: oily modest pressures. are required. 'Two, lowering the working fluid .pump work reduces the amount of heat transferred intothe working fluid by the pump itself. Also, a low width/length aspect ratio results in slower working fluid velocity which reduces amount of mixingõ but this otherwise desirable (from a heat exchange standpoint) effect is negligible in the present example sy-stem since the Reynolds numbers are typically 1000. 4..tggestitv a laminar flow regime. Furthermore, .a low Width/length aspect ratio significantly reduces the number of bends (or "corners") in the fluid flow path. These bends are areas of mixing for the fluid Which promotes heat transfer; Without them, a fluid boundary layer builds up. However, this effect is offset herein by maintaining a narrow slot between the cold plates. This way the primary heat transfer mechanism is by conduction, but the conduction path length (and therefore boundaty layer) is small, resulting in A relatively high rate of heat transfer:
in preferred examples, the membranes 66, 68 are stretched under tension during assembly to the frame, prethrably (Le., in tension between the top and bottom rails 53, 51 and also in tension between the left mid right side rails 54), This tension can be maintained over the shelf life of the produet Pretensioning minimiies wrinkles in material, which is beneficial because wrinkles can impede working fluid flow and create air gaps which reduce heat transfer between the working fluid and cold plates. Wrinkles can also complicate insertion of the membrane: assembly into the narrow slot 34, TO establish pre-tensioning of the membranes, the frame may be made in halves and posts such as threaded fasteners can extend transversely to one half of the frame, with the membranes 6,68 being stretched over the posts and holes made in the membranes to receive the posts. The other half of the frame is then. positioned to sandwich a rectilinear border portion of the membrane assembly between the frame halves, and a: closure such as respective nuts engaged with the posts to hold the frame halves together With the membrane aSsembly held in tension between the frame halves Figure ..4 shows that the working fluid chamber is closed off at the bottom by a bottom seam 74A of the membrane assembly, which is part of the border portion 74., In addition to: applying tension to avoid wrinkling during use, additional pegs May be tts4 to avoid wrinkling during the welding process, improving :the quality of the weld Joints.
In the border portion 74, at least one and preferably more layers ofpolymer film may be used to reinforce the membranes 66, 68 to establish welded seams through which (at the sideS of the mernbrane assembly) the post holes are formed, allowing for eagET
fabrication.
By placing reinforcing layera on the border portion 74 only, the central 'widow" of the membrane assembly consists only of a single thin layer membrane 'between the working fluid and one of the cold plates 30,32 to minimize itripeding heal transfer.
A=die,eut reinforcement layer may. be used which reinforces the entire perimeter with one piece of material:
In some examples, the polymer membranes 66, 6$ are highly stretchable, at least greater than 25% elongation, This allows the membranes to change from the empty floState shown in Figure 4 to an inflated :Shape (withhl the slot 34 between the cold plates) without wrinkling. It also allows the membranes: to eaSily confiatin to features on the tams of the cold plates.
.Addi tionally, the membranes may be made of a material which c..7ari also be made into tubing. Tubes suet as the inlet and outlet tubes 58, 62 shown M Figure 4 can then be thermally welded (e,g, wing RF sealing) to the membranes, which is more reliable and quicker than adhesive bonding. The membranes 66, 68 need not provide their own lateral support because the cold plates 32, 34 and tram e provide the support for the:
irEllated membrane assembly, allowing it to withstand, the. pressure generated as 4 result of Working fluid flowing through between the membranes. Structural features such as raised bumps, concavities, raised ribs, and so on may be located on the cold plates to optimize heat transfer.
This can be economically advantageous because the cold plates are reusable components.
Manifolds can be cut into the cold plates to even out the distribution of saline fiew Having described an :example ion4ithiting thermal exchange combination of structure betweeii the heat exchanger M the control system 14 and the sterile 'working fluid in the WM:vascular temperature ckmttol catheter 12, attention is now directed to Figure 5 which shows an example enabodiment of additional:coolant chambers in the cold plates by Which to elect heat exchange with working fluid, including non-sterile *Orkin fluid, from the external beat exchange pad i& Note that the plate structures shown in Figure 5 preferably we metal or other material with high heat conductivity.
AS shoWn, the cold plates 30 12 may be. multi-plate:assemblies defining multiple fluid chambers, although in the discussion beloW they:are referred to generally as "plates" $0 and 32. In the non-limiting example shown, the refrigerant inlet and outlet tubes 38, 40 extend through an outer wall 80 and a separator wall 82 of the cold plate 32 to communicate refrigerant frorn the compressor 2.2 into the refrigerant passage:way 42 in the cold plate, which establishes a refrigerant chamber that is bounded by the separator wall 82 and an inner wall 84 On the other side of the inner wall 84 is the catheter Working fluid cassette: slot 34, As stated earlier, each cold plate may have its own I=efrigerant inlet and ondet tubes, or only one cold plate may be formed with refrigerant inlet and outlet tubes and the other cold plate either thermally coupled to the cold plate in which the refrigerant flows and/or receiving refrigerant from the Other cold plate through p:assageways Robed between the cold plate&
In the example shown, the cold plates 30, 32 are thermally ce up ed through the Side Walls 36 (Figure 2), a common bottom wall 86 (Figure 5), and thmugh the uninterrupted portiOns of atop wall $8 M which the slot 34 is formed, In ,one examples, the cold plates 30,, 32 are mirror image:structures of each other. M
the example of Figure 5, the refrigerant chamberm the left-hand cold plate (32) is in fluid communication through reffigeratit supply and return passagewa2,,N 90, 92 With a refrigerant chamber 94 in the right-hand cold plate 30. Thus, the refrigerant chambers ofthe cold plates straddle the cassette Slot 34 and are separated therefrom by respective inner walls 84; with refrigerant flOwing Serially through the left and right refrigenint chambers, first from the refrigerant inlet tube 38 into the left refrigerant chamber, then through the refrigerant Supply passageway 90, the left hand refrigerant chamber 94, back through the refrigerant return passageway 92,, and out the refrigerant outlet tube 40, This increases the refrigerant fluid flow ratelbrOugh the refrigerant chanthem when two refriwrant elunnbers are provided as in the example shown.
ha contrast, pad working fluid channel fluid flow may be plumbed in parallel to left and right pad fluid chambers which straddle the refrigerant chambers as shown and are =separated therefrom by respective separator walls 82. lin the non,limiting example shown, fluid from the external pad flow S thrOugh the pad working fluid inlet Pip itit0 an inlet plenum 100 formed in the bottona wall 86. The fluid flows in parallel through inlet pOrta IOZ 104 UM
left and right pad working fluid chambers 106, 108.. The fluid elicits the pad working fluid chambers through ait tipper plenum 110 formed in the top plate 88 and out of the working fluid outlet Pb,it back to the external pad. This exampIe parallel fluid flow reduces backpressure in the pad working fluidsystetn.

Note that the above-described series fluid flow through the refrigerant chambers and parallel flow through the pad working fluid chambers is exemplary only, and is not limiting.
Thug, fluid flow through the pall working fluid chambers my be in series and/or fluid flow through the refrigerant chambers may be parallel. Note farther that the particular example plumbing arrangements illustrated and desctibed are but one example of plumbing fluid through the multi-chamber cold plates 30, 32.
Indeed, figure 6 shows a: system similar to the one shown in Figure 5, except that fluid flow through the =refrigerant chambers is in parallel. Both refrigerant f;.,,hambess may communicate with a refrigerant inlet plea= 200 through which refrigerant flows into each refrigerant chamber 94.in parallel. Also, both refiieerant chambers may communicate with a refrigerant outlet plenum 202 through which refrigerant flows cut of each refrimunt chamber 94 in parallel back to the compressor.
It may now be appreciated that in: the intravaseular heat exChange Mode, working fluid from the eathever 12 flowing through the cassette 50 which is disposed in the :slot 34 exchanges heat with the refrigerant in the refrigerant chambers 42, 94 through the respective inner walls 84, The Catheter working= fluid comes into contact with no portion. of the cold plate heat exchanger, owing to it flowing through the cassette SO. In this Way, the catheter working fluid retains its sterility and is enclosed in a closed fluid circuit for withstanding circulation fluid pressures of,, e.gõ seventy pounds per square Mob (70 psi).
On the other hand, since pad working fluid is separated from the patient by at extemai gad, it may not require sterility, in which case the pad working fluid .contact s the separator plates 82 directly in the eold plates 30, 32 to exchange heat with the refrigerant in the refrigerant Chambers 42, 94.

While the particular HEAT EXCHANGE SYSTEM FOR PATIENT
TEMPERATURE CONTROL WITH MULTIPLE COOLANT CHAMBERS FOR
MULTIPLE HEAT EXCHANGE MODALITIES is herein shown and described in detail, the :Scope of the present inyehtiOn is to he limited by nothing other than the appended claims.

Claims (20)

1. A heat exchanger, comprising:
at least first and second heat exchange plate assemblies (30, 32) defining a first modality working fluid chamber (34) between them, the first modality working fluid chamber (34) being configured for receiving a holder (50) through which sterile working fluid can flow to and from a first modality patient heat exchange member (12) such that the sterile working fluid can exchange heat with the plate assemblies (30, 32) through the holder (50) without the sterile working fluid touching the plate assemblies (30, 32); and at least a second modality working fluid chamber (106, 108) through which second working fluid can flow to and from a second modality patient heat exchange member (18) such that the second working fluid from the second modality patient heat exchange member (18) can exchange heat with at least one of the plate assemblies (30, 32) by directly contacting at least one the plate assemblies (30, 32).

2. The heat exchanger of Claim 1, wherein the first modality patient heat exchange member (12) is established by an intravascular heat exchange catheter.

3. The heat exchanger of Claim 1, comprising the first modality patient heat exchange member (12).

4. The heat exchanger of Claim 1, wherein the second modality patient heat exchange member (14) is established by an externally-applied exchange pad.

5. The heat exchanger of Claim 1, comprising the second modality patient heat exchange member (14).

6. The heat exchanger of Claim 5, wherein the second working fluid from the second modality patient heat exchange member (14) is not sterile.

7. The heat exchanger of Claim 1, wherein the second modality working fluid chamber (106, 108) includes a first sub-chamber (108) in the first plate assembly (30) and a second sub-chamber (106) in the second plate assembly (32).

8. The heat exchanger of Claim 1, wherein each plate assembly includes at least one respective refrigerant passageway (42, 94) through which refrigerant can flow to heat or cool the respective plate assembly.

9. The heat exchanger of Claim 8, wherein refrigerant must flow in series through the refrigerant passageways such that all refrigerant must flow first through the refrigerant passageway of the first plate assembly (30) before flowing through the refrigerant passageway of the second plate assembly (32).

10. The heat exchanger of Claim 8, wherein refrigerant can flow in parallel through the refrigerant passageways.

11. The heat exchanger of Claim 7, wherein the second working fluid must flow in parallel through the first and second subchambers (106, 108).

12. A system comprising:
at least first and second plate assemblies (30, 32) through which refrigerant can flow through respective first and second refrigerant chambers (42, 94), the plate assemblies (30, 32) defining a slot (52) between them that can receive first working fluid from an intravascular heat exchange catheter (12), so that the first working fluid from the catheter (12) can be heated or cooled by the refrigerant flowing through the refrigerant chambers (42, 94); and the plate assemblies (30, 32) further including respective first and second working fluid chambers (106, 108) laterally outboard the respective first and second refrigerant chambers (42, 94) and configured for receiving second working fluid from an external heat exchange pad (14) to facilitate heat exchange between the second working fluid and the refrigerant.

13. The system of Claim 12, wherein the slot (52) is configured for receiving a cassette (50) through which the first working fluid can flow so that heat can be exchanged between the plate assemblies (30, 32) and the first working fluid without the first working fluid contacting the plate assemblies (30, 32).

14. The system of Claim 12, comprising the catheter (12).

15. The system of Claim 12, comprising the pad (14).

16. The system of Claim 12, wherein refrigerant can flow in series through the refrigerant chambers (42, 94) such that ail refrigerant can flow first through the refrigerant chamber (42) of the first plate assembly (32) befire flowing through the refrigerant chamber (94) of the second plate assembly (30).

17. The system of Claim 12, wherein refrigerant can flow in parallel through the refrigerant climbers (42, 94).

18. The system of Claim 12, wherein the second working fluid can flow in parallel through the first and second working fluid chambers.

19. A system comprising:
at least a first plate (82);
at least a first working fluid chamber (106) on a first side of the first plate (82);
at least a first refrigerant chamber (42) on a second side of the first plate (82) opposite the first side, such that heat exchange is facilitated through the first plate (82) between the first refrigerant chamber (42) and the first working fluid chamber (106); and at least a second working fluid chamber (34) separated from the first refrigerant chamber (42) by a wall (84) through which heat exchange may be effected between the second working fluid chamber (34) and the first refrigerant chamber (42).

20. The system of Claim 19, comprising:
at least a second plate, the first working fluid chamber (34) being between the first and second plates;
at least a second refrigerant chamber (94) on a side of the second plate opposite the first working fluid chamber (34), such that heat exchange is facilitated through the second plate between the second refrigerant chamber (94) and the first working fluid chamber (34);
and at least a third working fluid chamber (108) separated from the second refrigerant chamber (94) by a barrier through which heat exchange may be effected between the third working fluid chamber (108) and the second refrigerant chamber (94).