Abstract:
Equipment for thermal therapy of patients is disclosed. The equipment includes a flexible heat exchange structure having fluid conducting channels formed between two layers of flexible material, with improved liquid manifolds at the ends of the channels for resisting pinching, crimping or buckling in the manifolds on pressurization and when the heat exchange structure is subjected to flexure as when worn on the human body. The manifolds are configured so that pressurization shrinkage at the manifold is balanced with pressurization shrinkage laterally among the fluid conducting channels. In a preferred embodiment, the fluid conducting channels themselves are configured in a zig-zag pattern which is effective to resist buckling or pinching of the channels when the heat exchange structure is subjected to bending. In a further embodiment the flexible heat exchange structure includes a third layer of material to form a pressurized air envelope, for heat/cold and pressure therapy. This embodiment may include a fourth layer of flexible material, between the flow channels and the skin, for holding a liquid or gel to help disperse the heating or cooling from the fluid conducting channels more evenly against the skin. In another preferred embodiment the equipment includes a portable cart device for supplying heated and cooled liquid and air pressure for administering thermal therapy to a patient. The portable cart includes a heated liquid reservoir, a cooled liquid reservoir and a liquid mixing valve, effective to allow instant changes in temperature as desired for delivery through a patient therapy heat exchange device in contact with the patient. Liquid returning from the patient therapy is divided into portions to be heated and cooled in the same proportion as the mixing valve is currently set to deliver the mixed heated and cooled liquids.

Description:
REFERENCE TO RELATED APPLICATION  
       [0001]    This application is a continuation-in-part of application Ser. No. 431,753, filed Nov. 6, 1989, now U.S. Pat. No.______, which was a division of application Ser. No. 250,778, filed Sep. 28, 1988, now U.S. Pat. No. 4,884,304. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The invention relates generally to heat exchange devices for heating and/or cooling of the human body, and more particularly to a patient therapy heat exchange structure for placing against or for being worn on the human body. The heat exchange structure can be in combination with a cooperating portable device, which may be in the form of a wheeled cart, for providing heating and/or cooling liquid to the patient therapy device at a desired temperature, with or without cyclic pressurization.  
           [0003]    U.S. Pat. No. 4,691,762 discloses a temperature control system including a heat exchanger vest and/or helmet to be worn on the human body, accompanied by a portable unit which administers cooling to a circulated liquid which passes through the heat exchange garments. The heat exchange garments pursuant to that patent were advantageously formed as Flexitherm (a trademark of Life Support Systems, Inc.), a material, fabricated of two sheets of flexible, liquid-impervious plastic material heat sealed together to form the fluid conducting channels with appropriate manifolding.  
           [0004]    The Flexitherm heat exchange material as constituted prior to this invention had a tendency to exhibit flow constriction problems under certain circumstances. For example, in areas where the heat exchange material was subjected to relatively sharp bends, crease lines could form in the manifolds and in the fluid conducting channels themselves due to the stresses of bending the material when pressurized with flowing liquid. These stress lines or crease lines could become deep creases and shut off flow to some flow channels and through some portions of the manifolds. The problem was accentuated further by the imbalance in pressurization shrinkage between the flow channels and the manifolds. The flow channels shrink in lateral dimension when pressurized with liquid, since the flattened channels become “inflated” to a generally cylindrical configuration, drawing the structure inward laterally. Adjacent manifolds, which are generally perpendicular to the orientation of the flow channels, shrink in the perpendicular direction, but essentially do not shrink in the direction of shrinkage of the flow channels. Upon pressurization this imbalance tended to put increased stress on the manifolds, tending to form constrictions which were even more greatly accentuated when the Flexitherm heat exchange structure was formed around curves and bends on the body.  
           [0005]    These problems limited the usefulness of the Flexitherm material for additional therapy situations which might require relatively sharp bends and flexing situations.  
           [0006]    Co-pending application Ser. No. 431,753, which was a division of application Ser. No. 250,778 (U.S. Pat. No. 4,884,304), disclosed a bedding system with liquid heating or cooling, wherein the liquid temperature control was provided by a mixing device which mixed warm liquid with cooled liquid as selected by the user, for maximum comfort. This provided for fast-response adjustment of temperature (and individual control in a dual control system) in the liquid flow channels of the bedding system, to quickly achieve the proper temperature for the particular user.  
           [0007]    Such closed-loop mixing of heated and cooled liquids, to quickly achieve changes in temperature in a liquid-conducting flexible heat exchange device, was not generally available prior to the present invention. Conventional systems which have been in use have had only a single liquid tank, with the requirement of changing the temperature of water in the tank in order to achieve a change in temperature in a heat exchange device served by the tank. For example, heating/cooling devices of this general type have been available from Zero Cincinnati, Baxter Medical and Jobst.  
           [0008]    It is an object of the present invention to provide an improved flexible heat exchange structure which may be used for thermal therapy on a patient or for other body cooling purposes, and this may be in conjunction with a portable source of heated and/or cooled liquid, and optionally air pressure, connected to the heat exchange structure or garment by fluid lines, for achieving very fast response in temperature adjustment for the patient thermal therapy.  
         SUMMARY OF THE INVENTION  
         [0009]    In accordance with one embodiment of the invention, a flexible heat exchange structure, which may be used for heating and/or cooling of the human body, particularly for medical purposes but also for body thermal control in extreme environments, has a plurality of fluid conducting channels for carrying a heat exchange liquid. The channels are formed between a pair of flexible sheets of material, substantially impervious to the heat exchange liquid, with the sheets sealed together along generally parallel lines to form the liquid conducting channels between the lines. At the ends of the series of liquid conducting channels are manifolds for conducting the heat transfer liquid into the series of channels and out of the series of channels.  
           [0010]    The pair of flexible sheets are sealed together around the series of liquid conducting channels along peripheral seal lines, spaced away from the ends of the channels in manifold portions so as to define the manifolds for inflow and outflow of liquid. In accordance with the invention the manifold portions of the seal lines have portions formed in a convoluted or undulating pattern. This pattern tends to discourage pinching of the fluid manifolds when the flexible heat exchange structure is subjected to bending or flexure as when worn on the human body. Further, the convoluted or undulating manifold seal lines tend to reduce buckling stress in the manifolds on pressurization of the heat exchange structure, by balancing pressurization shrinkage at the manifold portions of the seal lines with pressurization shrinkage laterally among the liquid conducting channels.  
           [0011]    The sheets of flexible material preferably are heat sealed to form the seal lines, with the heat seals in a preferred embodiment being approximately 0.1″ wide. Between the heat seal lines the fluid conducting channels may be approximately 0.15″ wide when in flattened configuration. The convolutions in the manifold seal lines may have a width of about 0.5′, forming a relationship discussed further below.  
           [0012]    The convoluted or undulating pattern of seal lines can comprise a pattern of generally curved undulations, the undulations each having a width which is selected to shrink, upon pressurization of the heat exchange structure with fluid, to the same degree that the liquid conducting channels on the other side of the manifold shrink in width. This avoids the differential pressurization shrinkage mentioned above. The undulations may be generally semi-circular in shape, or U-shaped, or they may V-shaped, with the open side of the U or V shape facing toward the series of liquid conducting channels on the other side of the manifold. In a preferred embodiment the apices of the generally curved undulations (“generally curved” includes V-shaped undulations), are positioned to be oriented generally toward the center of the open end of every second flow channel on the other side of the manifold, and generally equidistant from the two heat seal ends of the respective flow channels.  
           [0013]    In a further preferred embodiment, the flow channels or capillaries of the heat exchange structure, while still being generally linear in an overall sense, are formed by seal lines in zig-zag patterns, the seal lines being regular repeating zig-zag lines generally equally spaced apart to form the liquid conducting channels between them. This zig-zag pattern of the channels tends to discourage pinching of the channels when, the flexible heat exchange structure is subjected to bending or flexure, particularly around relatively tight bends or curves, as when worn on the human body.  
           [0014]    In a further implementation of the invention a third flexible sheet of material is secured to the two-ply material, connected by sealed connection to one side of the fluid channel structure. This forms an air envelope between one of the pair of flexible sheets and the third sheet. Pressurized air can be received in this air envelope, to pressurize the heat exchange therapy device against the skin, such as on a human limb or torso, so that a combination of thermal therapy and pressure therapy can be applied to an injured area. The pressure also aids in conducting the heating or cooling into the skin, and it can be effective to control blood flow or swelling in the treated area.  
           [0015]    In a still further implementation, a fourth sheet of flexible material is secured to the heat exchanger/fluid channel structure, on the opposite side from that of the air envelope. This forms a liquid or gel envelope within which a liquid or gel is contained, preferably permanently. The liquid or gel envelope disperses heating or cooling evenly against the patient&#39;s skin, especially when the air envelope is pressurized. This is important in critical hyperthermia or hypothermia treatment, where relatively extreme temperatures are involved and it is undesirable to have the thermal treatment applied in the discrete lines of the flow channels.  
           [0016]    The apparatus of the invention further includes a portable device, which may be in the form of a wheeled cart, for administering the thermal therapy to a patient via the flexible heat exchange structure worn by the patient. Included in the portable device are two reservoirs, a heated liquid reservoir and a cooled liquid reservoir. A return reservoir, also for filling, preferably also is included. A mixing valve is provided to enable selection of precise temperature desired for the patient therapy, by adjusting the mixture of heated liquid and cooled liquid to be delivered to provide the correct temperature. Instantaneous changes may be made, as desired in certain types of patient therapy, by shifting of the mixture. Adjustments may be made anywhere from 100% cooled liquid to 100% heated liquid, by adjustment of the mixing valve.  
           [0017]    Liquid which has passed through the patient therapy flexible heat exchange device via a pump reenters the portable apparatus into a return area. This return liquid is heated or cooled proportionally in accordance with the current setting of the mixing valve, as it re-enters the respective reservoirs. This provides for maximum efficiency of the portable device, and is advantageously achieved by providing closed, (substantially) full reservoirs which may have the chiller/heater unit inside the reservoir or in contact with the reservoir. The closed, non-vented reservoirs automatically receive the same return flow rate as the outgoing flow rate. Preferably a return reservoir, vented to. atmosphere, first receives the return liquid, and the liquid is pumped from the return reservoir to the cooled and heated reservoirs in accordance with outflow from each reservoir.  
           [0018]    Preferably the portable device also includes a source of pressurized air, i.e. a small compressor or pressurized air supply. This provides pressurized air for use in the air envelope discussed above, for administering pressure as well as hot/cold therapy to a patient.  
           [0019]    It is therefore among the objects of the invention to provide improved apparatus and methods for administering cooling and/or heating to the human body, including a relatively constriction-free thermal flexible thermal therapy heat exchanger and a portable device for fast-response adjustment of hot/cold therapy. These and other objects, advantages and features of the invention will be apparent from the following description of preferred embodiments, considered along with the accompanying drawings. 
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0020]    [0020]FIG. 1 is a plan view showing a heat exchanger vest in flattened configuration, as one example of an improved construction of Flexitherm fluid heat exchange material.  
         [0021]    [0021]FIG. 2 is a detail view showing a portion of the flexible heat exchange structure of FIG. 1.  
         [0022]    [0022]FIG. 3 is a detailed plan view schematically showing a portion of a flexible heat exchange structure similar to that of FIG. 1, but including fluid flow channels formed in zig-zag patterns.  
         [0023]    [0023]FIG. 3A is a plan view showing an entire heat exchange garment configured as shown in FIG. 3.  
         [0024]    [0024]FIG. 4 is a view showing a three-ply or three-layer flexible heat exchange structure, similar to that of FIGS. 1 through 3 but including an additional layer of flexible material forming an air envelope for pressurization of the device during therapy.  
         [0025]    [0025]FIG. 5 is a view similar to that of FIG. 4, but showing a four-ply or four-layer flexible heat exchange device, with the fourth layer forming a liquid or gel envelope to be placed against the patient, for more even distribution of heat or cooling from the heat exchanger channels.  
         [0026]    [0026]FIG. 6 is a view in perspective showing the heat exchanger structure of FIG. 5 in use for patient therapy.  
         [0027]    [0027]FIG. 7 is a schematic view showing a portable device, which may be in the form of a cart, for providing heated liquid, cooled liquid, selected mixtures of the liquids, and for providing air pressure for uses such as in FIG. 6.  
         [0028]    [0028]FIG. 8 is a view in perspective showing the portable device of FIG. 7, in use with a flexible heat exchange therapy device, such as that of FIG. 4 or  5 .  
         [0029]    [0029]FIG. 9 is a view similar to FIG. 7, but showing a modified portable device capable of serving the treatment of several patients simultaneously, at different temperatures. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0030]    In the drawings, FIG. 1 shows a heat exchange garment which is essentially of the type shown in FIG. 4 of U.S. Pat. No. 4,691,762, assigned to the same assignee as the present invention. The illustrated garment  10  is a vest for heating or cooling of the torso as shown, for example, in FIGS. 1A through 1F of the patent. The principles of the improved heat exchange garment  10  described herein are applicable to other garments or thermal therapy devices to be applied to the body, and to the temperature controlled bedding system disclosed in copending application Ser. No. 431,753 and U.S. Pat. No. 4,884,304.  
         [0031]    As shown in FIG. 1, the heat exchange garment or thermal therapy device  10  is formed of a pair of sheets of flexible, liquid-impervious material (one side or layer  12  is visible in FIG. 1), sealed together along seal lines  14 ,  16 ,  18 ,  20 , etc. As in the above referenced patent, the seal lines are preferably formed by heat sealing of layers of plastic material, as in the two-ply material known as Flexitherm. Thus, the sheets of material may comprise nylon, nonex or wool fabric coated with urethane, vinyl or other impermeable thermo setting plasters, for example.  
         [0032]    Thus, the seal lines  16 , shown in FIG. 1 as being linear seal lines in this case (they can be non-linear), form parallel fluid conducting channels  24  which act as fluid flow capillaries of the flexible heat exchange device  10 . A peripheral seal line  14  forms the outermost capillary  24 , while other peripheral seal lines  18 ,  20 ,  22  form manifolds for inflow and outflow of liquid to and from the capillaries or fluid conducting channels  24 . Thus, as shown in the drawing, manifolds or manifold portions  26 ,  28 ,  30 ,  32 ,  34  and  36  are formed at the periphery of the garment or thermal therapy heat exchange device  10  in the configuration shown.  
         [0033]    A principal feature of the present invention is that the primary manifolds of the flexible heat exchange device are configured to shrink with pressurization in such a way as to balance the pressurization shrinkage exhibited by the capillaries or flow channels  24 . The heat exchange device  10  is formed flat, of two flat sheets sealed together. Typically a panel of the heat exchange material might have channel widths of 0.15 inch, with a 0.10 inch heat seal width. Upon pressurization with liquid, the capillaries or channels expand to a generally cylindrical shape, so that each channel has an approximate circumference of 0.30 inch. Assuming the cylindrical shape, the channel would then have a pressurized diameter of about 0.095 inch, as compared to the original flat width of 0.15 inch. Considering each channel and an adjacent heat seal width, the amount of shrinkage is 0.25 inch (flat) less 0.195 inch (pressurized), so that the foreshortening of the heat exchange device, laterally across the capillaries, shrinks the pressurized panel to about 0.195/0.25, or 78% of the flat panel dimension.  
         [0034]    In prior flexible heat exchange devices of this nature, such as illustrated in U.S. Pat. No. 4,691,762, this lateral shrinkage was not balanced by a corresponding shrinkage in the fluid inlet and outlet manifolds. However, in accordance with the present invention the manifold seal lines ( 18 ,  20 ) are formed in an undulating or convoluted or zig-zag pattern. FIG. 1 shows one preferred embodiment wherein the convolutions are generally C-shaped, with apices  38  formed at connecting points. As illustrated in FIG. 1 and more particularly in FIG. 2, the heat seals  20  may form a double width at the point of the apex  38 .  
         [0035]    For best results in avoidance of stress, folding and crimping lines which can tend to pinch off the manifolds, it is preferred that the apices of each convolution or undulation are oriented at every second flow channel  24  on the other side of the fluid manifold  26 ,  30  or  36 . This has been found to be most advantageous in avoiding extreme creasing in pressurization and in the bending or flexing of the heat exchange device around relatively sharp bends, such as when used to wrap a limb for thermal therapy on a patient. The convolutions or undulations  40  cause the manifolds to shrink on pressurization, and these convolutions are shaped and sized so as to approximately balance the shrinkage which occurs laterally among the fluid flow channels  24 . This eliminates most of the stress which would cause pinching or constriction of the fluid manifolds, an effect which is accentuated when the heat exchange garment is wrapped around tight bends.  
         [0036]    Through working with the improved thermal therapy heat exchange device such as shown in FIGS. 1 and 2, it has been found that minimal stress lines occur on pressurization, usually a minor stress line forming along the lines  42  indicated in FIG. 2, extending between a convolution apex and approximately the end of the heat sealed lines adjacent to the facing flow channel. Little or no flow constriction is caused when the material is unflexed. When the material is wrapped laterally around a limb, for example, for thermal therapy of a patient, with the lines of the capillaries being wrapped circumferentially around the limb, a slight creasing or folding tends to occur at the back of the manifold  26 , i.e. the layer of material which is closest to the skin. The outer layer then becomes taut, exhibiting virtually no creasing, and the manifold becomes only slightly constricted, well within a tolerance which continues to provide adequate flow through the flexible heat exchange device.  
         [0037]    An example of preferred dimensions of a flexible heat exchange device in accordance with the invention is outlined below, showing the balancing of pressurization shrinkage at the manifold and at the capillaries. In this example the convolutions are C-shaped or V-shaped (zig-zag) and are 0.5 inch on centers. All heat seal widths are 0.10 inch. The capillaries or fluid flow channels are 0.15 inch wide when flat, between adjacent heat seals.  
                                                 ANALYTICAL CLARIFICATION OF SEMI-CIRCLE       OR ZIG-ZAG MANIFOLDING                                A.   Nominal Heat Seal Width   0.10″           B.   Nominal Channel Width =   0.15″       C.   Channel Circumference =   2(0.15) =   0.30       D.   Channel Diameter =    .3″/π =   0.09549″       E.   Ratio of Inflated Dimension =   (.1″ + 0.09549″)/ =   0.782           to Flat Dimension =    .25″       F.   Manifold “V” or “C” =   0.5″ (on centers,               flattened)       G.   Nominal Heat Seal Width =   0.10″       H.   Maximum Manifold Width =   0.5″− 2(0.10″) =   0.30″       I.   Manifold “V” or “C” Diameter =   2(0.30″)/π =   0.191″       J.   Ratio of Inflated Dimension =   0.191″ + 0.2″/   0.782″           to Flat Dimension =   0.5″ =                          
 
         [0038]    As shown in FIG. 1, with the type of vest garment illustrated, the angle of the manifolds with the generally horizontally extending flow channels or capillaries  24  will vary depending on location. Thus, the convolutions or undulations in areas where the manifold is deeply angled away from perpendicular to the flow channels will need to be wider apart between the apices in order to maintain a relationship of orientation toward the end of every second flow channel. This will cause the pressurization shrinkage relationship to vary slightly, but not enough to appreciably inhibit flow through the manifolds, even when the flexible heat exchange device is wrapped around a limb or torso. In the manifold areas  28 ,  32  and  34  shown in FIG. 1, for example, the manifold is at an angle of less than about 45° to the flow channels. In this situation the differential shrinkage problem is minimized or avoided, without the typical undulations, by the fact that the manifolds are closer to alignment with the flow channels, which do not exhibit pressurization shrinkage in the longitudinal direction.  
         [0039]    [0039]FIG. 3 schematically indicates a modified embodiment of the flexible heat exchange device of the invention. The convoluted or undulating manifold seal line  20   a  is shown as a zig-zag seal line, i.e. made up of V-shaped convolutions rather than U-shaped convolutions as in FIGS. 1 and 2. It should be understood that this configuration can be used in lieu of the U-shaped convolution pattern shown in FIG. 1, and in fact FIG. 1 shows a portion of a return manifold baffle  44  having the zig-zag or V-shaped configuration.  
         [0040]    The principal difference of the embodiment shown in FIG. 3 is the zig-zag configuration of the capillary or flow channel seal lines  46 . These seal lines  46  are formed as regular repeating zig-zag lines which remain essentially equidistant from each other and in conforming patterns, as illustrated in FIG. 3. The arrows in FIG. 3 represent stress lines which tend to be formed, extending from the apices of the zig-zag or semi-circular U-shaped manifold convolutions to the ends of seal lines at the channels across the manifold. As the improved flexible heat exchange structure of FIG. 3 is bent and flexed as in thermal therapy on a patient, it is observed that the stress lines are accentuated at the inside of the bend (e.g. the layer of material closest to the skin), while becoming less apparent or entirely disappearing on the outside layer of material at the same bend. For every apex in the manifold, two stress lines are formed to the facing ends of the heat seal lines defining the capillary channel. Thus, the stress of each line is one-half that of the previously known Flexitherm, referred to above. This results in at least a two time reduction in bending radius without occlusion of flow. This bending characteristic makes the new material far more compliant, enabling relatively sharp flexing of the material without occluding the flow of liquid either through the manifold or the channels.  
         [0041]    [0041]FIG. 3A shows a full thermal vest  45  which is configured with the zig-zag flow channel heat seal lines. Manifold seal lines include zig-zag portions or V-shaped portions and U-shaped portions.  
         [0042]    [0042]FIG. 4 is a schematic view in cross section, showing a three ply or three layer flexible heat transfer structure  50  in accordance with the invention. The flexible heat transfer device  50  is similar to that shown in FIGS. 1, 2 and  3 , and may incorporate the configurations illustrated in those figures, in respect of two layers  52  and  54  which form liquid flow channels or capillaries  56 , with seal lines  58  between them. In the heat exchange structure  50  of FIG. 4, an additional layer or ply  60  is included, on the outside of the heat exchange device, i.e. the side away from that which will engage a patient when the device is used for thermal therapy. The outer ply or layer  60 , which is sealed to the other layers at peripheral seal lines  62 , forms an air envelope  64  capable of containing pressure. This enables the heat exchange device  50 , when wrapped around or against a patient&#39;s limb, torso, etc., to be pressurized to apply pressure against the treatment area. For example, one p.s.i.g. or slightly higher pressures are sufficient to effect certain types of pressure therapy while also administering heating and/or cooling therapy through the liquid conducting channels  56 .  
         [0043]    [0043]FIG. 4 schematically indicates liquid loop elbow fittings  66 ,  68  and  70  passing through the air containment layer  60  and through the outer liquid containment layer  52  in sealed relationship for conducting liquid into or out of the liquid flow channels  56 . These fittings are repeated elsewhere to complete the inlet/outlet liquid loop. FIG. 4 also shows an air pressurization elbow fitting  72  for receiving pressurized air when the air containment envelope  64  is to be pressurized.  
         [0044]    [0044]FIG. 5 is another schematic view in elevational cross section of a heat exchange structure  75  which is similar to that described in FIG. 4 but with a further layer or ply  76  secured to the liquid conducting channel structure at peripheral seal lines  62   a . This lower ply or fourth ply is attached to the liquid conducting structure at the opposite side from the location of the air containment layer or ply  60  and the air envelope  64 . The lower or fourth ply  76  forms a heat dispersing envelope  78  which contains a thermally conductive liquid or gel, preferably sealed into the envelope  78  permanently. When heated or cooled liquid flows through the liquid conducting flow channels  56 , this liquid or gel envelope  78  assures that the heat or cooling will not be limited to specific lines of application, but will be dispersed properly against the skin of the patient. This is particularly critical in hyperthermia treatment for cancer, where fairly high temperatures (e.g. 106° to 108° F.) are involved. The pressurization of the air pressure chamber  64 , with the four ply structure  75  wrapped around a treatment area and pressed against the skin via the pressure, would otherwise tend to apply the high heat along specific lines at the location of the liquid channels  56 .  
         [0045]    The structure and function of the four ply thermal/pressure therapy device  75  is otherwise similar to that described above relative to the three-ply structure  50 .  
         [0046]    [0046]FIG. 6 illustrates the four ply thermal/pressure therapy device  75  in use on a patient, in this case showing therapy applied to the knee and surrounding areas of the leg. The heat exchange structure  75  includes the air pressurization envelope and containment layer  60  just below a restraint layer  77  which holds the therapy device in place on the patient. The restraint layer  77  wraps around the leg or torso, retaining the thermal/pressure therapy device  75  against the leg or torso. It may be retained in position with Velcro hook and loop fasteners. The drawing is cut away to show the two-ply liquid channel structure (layer  52  is visible). Below the two-ply channel structure is the liquid or gel material  78  (see FIG. 5) and the bottom flexible layer  76 . FIG. 6 can be considered to also illustrate the device  50  of FIG. 4, which also has the air pressurization envelope but not the liquid or gel envelope  78 .  
         [0047]    As shown in FIG. 6, a supply line or “umbilical cord”  82 , which may be covered with fabric or other insulative material, feeds heat exchange liquid to and from the device  75  for heat exchange via the liquid conducting channels, and also includes and air line for feeding pressurized air into the air envelope  60 . At the other end of this supply  82  is a heating, cooling and compressed air unit  84 .  
         [0048]    [0048]FIG. 7 is a schematic diagram illustrating the principal operative components of a portable unit such as the unit  84  shown in FIG. 6. The unit  84   a  illustrated in FIG. 7 may be in the form of a wheeled cart such as shown in FIG. 8, discussed further below.  
         [0049]    As indicated in FIG. 7, the heat/cold/pressure supply unit  84  has a cooled liquid reservoir  86 , a heated liquid reservoir  88 , and a temperature control unit  90 . In preferred embodiments, refrigeration or cooling coils  92  are directly in the liquid reservoir  86 , and heating coils  94  are located directly in the liquid reservoir  88 . These reservoirs preferably are closed and sealed, with a constant balance between liquid flowing out and liquid returning, as to each reservoir.  
         [0050]    Liquid is delivered at a temperature selected via the temperature control unit  90  which mixes heated and cooled liquid to achieve the proper temperature in an outlet line  96 . This liquid is delivered to the thermal therapy device  98  which is in contact with the patient, and which may be similar to the heat exchange garment  10  shown in FIG. 1 or  3 , the three ply heat exchange/pressure device  50  shown in FIG. 4, or the four ply heat exchange/pressure unit  75  shown in FIG. 5. In any event, the liquid at selected temperature passes through capillaries of the thermal therapy device  98  and returns to a return area through a return line  100 , ultimately to the cool and hot liquid tanks  86  and  88 . The return line  100  could go directly to branch lines  102  and  104  leading to the cooled and heated liquid tanks if desired, provided some resilient expansion or accumulating capability is provided in the tanks  86  and  88  to allow for changes in volume of the closed loop system. This is necessary, for example, if a dry thermal therapy device  98  is connected to the system  84   a , absorbing some of the liquid therein. In the arrangement just described, the liquid pump shown at  106  would be located in the line  96  so as to assure that positive pressure exists in the thermal therapy garment device  98 .  
         [0051]    However, a more preferred system is indicated in FIG. 7, including a return reservoir  108  receiving liquid from the liquid return line  100 , and preferably vented to atmosphere (but alternatively sealed and expandable). Flexibility in the total volume of the system can thus be accommodated with the reservoir  108 . The liquid pump  106  is then located just downstream of the return reservoir  108 , delivering liquid at positive pressure to the cooled reservoir  86  or the warm reservoir  88  in the same proportion as liquid is being delivered from these respective reservoirs via the temperature control unit/mixing valve  90 . Thus, the two reservoirs  86  and  88  can be rigid, closed and virtually completely filled at all times, and the positive pressure of the liquid pump  106  will push liquid from the reservoirs  86  and  88  in the desired proportion as set by the mixing valve  90  into the thermal therapy device  98 . There is no draw on the return line  100 , and negative pressure exists nowhere in this closed loop system except in a line  110  at the suction side of the pump, drawing liquid from the return reservoir  108 .  
         [0052]    As shown in FIG. 7, the portable unit  104   a  also preferably includes an air pump or air compressor  112 , which delivers pressurized air via an air pressure control unit  114  and a delivery line  116  to the thermal/pressure therapy unit  98 , which may be of the type shown in FIGS. 4 and 5, having a pressurized air envelope.  
         [0053]    The liquid mixing valve  90 , feeding hot and cold liquids mixed as selected to the thermal therapy device  98 , is an important feature of the invention. As noted above, this arrangement allows nearly instantaneous changes in the temperature of therapy administered. In some types of therapy, for example in the treatment of sports injuries, there might be prescribed  48  hours of cooling therapy followed by alternate heating and cooling. The control system  84   a  indicated in FIG. 7 is very apt for this purpose.  
         [0054]    Further, the temperature control device/mixing valve  90  can be connected to a microprocessor or programmed controller shown schematically at  118 , or can contain such a microcontroller. This can enable the physician or therapist to preset timed sequential thermal changes as for the sports injury therapy noted above. Further, this can enable the most rapid approach possible to a target temperature, without overshooting the temperature. For example, in whole body hyperthermia for cancer treatment, relatively high temperatures are involved. In approaching a temperature of 108° F., for example, the controller might rapidly increase temperature at the thermal therapy unit  98  (which can be detected via a site temperature feedback line  119  or a feedback line  119   a  from the delivery line  96 ) to about 106° , then can increase the temperature on a slower basis, monitoring feedback through the line  119 , until the precise desired temperature is reached. During the therapy, the desired temperature can be maintained in this same way, by feedback from the thermal heat exchange device  38  and control by the microcontroller  118 . Electrically controlled valves, including solenoid operated valves, are available for this purpose.  
         [0055]    In thermal therapy involving extreme temperatures, such as the whole body hyperthermia mentioned above, the temperature control enabled by the invention is extremely important. If in hyperthermia the body temperature rises to a dangerous point, which can cause heart fibrillation or brain damage, it is important to cool the patient very quickly. With conventional apparatus prior to this invention, it was necessary to quickly remove thermal covering from a patient and plunge the patient in a cold water or ice bath.  
         [0056]    It should also be noted that several previous hyperthermia systems used a heavy rubbery blanket over the patient, which was somewhat insulative. A high temperature was used to achieve the desired temperature against the body, sometimes at 125° , far higher than the delivery temperature and higher than the skin burn temperature of about 113° . The present system delivers the desired temperature far more efficiently, without anywhere exceeding the skin burn temperature.  
         [0057]    The thermal control system  84   a  shown in FIG. 7 automatically replenishes the hot and cold reservoirs  86  and  88  with the same amount of liquid being withdrawn, due to the fact of the reservoirs being closed. Whether a return liquid reservoir is included (vented to atmosphere or closed but expandable/contractible), the same desired effect can be achieved, as noted above.  
         [0058]    [0058]FIG. 8 shows a cart  120  embodying the thermal/pressure supply unit  84   a  shown in FIG. 7. The portable device  120  preferably is in the form of a cart with wheels  122 . Its size can be quite small, limited primarily by the volume of liquid (preferably water or treated water) which needs to be included in the cooling reservoir  86  and the heating reservoir  88 . These volumes should be sufficient that a preselected temperature range can be maintained in each reservoir even though liquid may be returning to the two reservoirs at substantially different temperature from the reservoir temperature. Smaller volumes can be used in the reservoirs  86  and  88  provided the chilling element  92  and the heating element  94  have sufficient power to return the reservoirs quickly to the selected temperature range, or to maintain the exiting liquid at each reservoir at the desired range. As long as the desired temperature at the patient is not below that of the cold reservoir or above that of the hot reservoir, the desired therapy can be executed. The important consideration is that the system not be overloaded, such that the chilling and/or heating capacity is reduced below therapy requirements due to repeated turnover of mixed liquid back to the reservoirs. This of course depends on the size of the thermal therapy device(s)  98  and the difference between therapy temperature and body temperature for the particular therapy.  
         [0059]    [0059]FIG. 8 shows a control panel  124  on the cart or portable device  120 , for entering desired therapy parameters and for monitoring temperature at the patient therapy device  98 , as discussed above. Details of the panel are not shown. A removable cover  126  can be provided in the top of the unit, primarily for access to the return liquid reservoir  108 , which also serves as a fill reservoir for adding makeup liquid. On the side of the portable device  120  is shown another openable panel  128 , for access to contained components.  
         [0060]    The cord  82  is shown with several lines, including the liquid delivery line  96 , the liquid return line  100  and the pressurized air line  116 . Also included in this cord or bundle  82  is the thermocouple line  119  (or  119   a —see FIG. 7) which feeds back the temperature of the thermal therapy device  98  to the controller.  
         [0061]    [0061]FIG. 9 shows a modification of the system shown in FIG. 7, demonstrating that the same system can be used to serve two or more patient thermal therapy devices  98 . A common cool liquid reservoir  86  and a common heated liquid reservoir  88  can serve cooled and heated liquid lines  130  and  132  leading to two different temperature control liquid mixing valves  90  and  90   a , as shown. Temperature can thus be controlled individually to the respective thermal therapy units  98 . The power and response time of the chiller  92  and the heater  94  should be sufficient to serve multiple thermal therapy devices  98  simultaneously.  
         [0062]    The microprocessor  118  is shown serving both temperature control mixing valves  90 ,  90   a . It can receive temperature feedback from thermocouple lines  119  or  119   a  (for the controller  90 ) and  119   b  or  119   c  (for the controller  90   a ).  
         [0063]    The two therapy units  98  are shown receiving compressed air from the air pressure control unit  114 . Pressure regulators (not shown) for individual control of pressure therapy can be included if desired. The microprocessor  118  is indicated as controlling the air pressure control unit  114 .  
         [0064]    The above described preferred embodiments are intended to illustrate the principles of the invention, but not to limit its scope. Other embodiments and variations to these preferred embodiments will be apparent to those skilled in the art and may be made without departing from the spirit and scope of the invention as defined in the following claims.