Patent Publication Number: US-2007118194-A1

Title: Non-ambient temperature therapy system with automatic treatment temperature maintenance

Description:
TECHNICAL FIELD  
      The present invention relates generally to a system for treating bodily injuries and ailments by cooling or heating the affected region of the body, and more particularly, to a non-ambient temperature therapy system which circulates a heat transfer fluid through a heat transfer pad mounted on the affected region of the body of a patient.  
     BACKGROUND OF THE INVENTION  
      Bodily injuries and ailments are commonly treated by applying a non-ambient temperature material to the affected region of the body. For example, a low temperature material, typically applied in the form of cold water, ice or a cold pack, may advantageously inhibit swelling in the region of the injury. A high temperature material, typically applied in the form of hot water, a hot pack or an active heating element, may advantageously reduce pain and promote healing. A number of splint devices are known in the art for applying non-ambient temperature materials to injured or otherwise ailing regions of the body as evidenced by U.S. Pat. No. 3,548,819 to Davis et al; U.S. Pat. No. 3,901,225 to Sconce; and U.S. Pat. No. 4,706,658 to Cronin. One disadvantage of such devices is that the low temperature materials become warmer as they remain in contact with the body during treatment and the body transfers heat to the low temperature materials. Conversely, high temperature materials become cooler as they transfer heat to the body. This disadvantage can be remedied by periodically replacing the non-ambient temperature materials. However, constant replenishment of these materials is cumbersome and inconvenient, and results in periodic treatment temperature fluctuations.  
      In response to this problem, a number of systems have been developed for continuously circulating a cooling fluid from a low temperature reservoir to a desired body location. Such systems are typified by U.S. Pat. No. 2,726,658 to Chessey; U.S. Pat. No. 3,683,902 to Artemenko et al; and U.S. Pat. No. 4,962,761 to Golden. These fluid circulation systems in general are relatively complex, rendering them costly to manufacture and maintain, as well as difficult to operate. Accordingly, the systems are not practical for widespread use.  
      U.S. Pat. No. 5,241,951 to Mason et al discloses a therapeutic treatment system which rectifies the shortcomings of the above-referenced fluid circulation systems. The therapeutic treatment system of U.S. Pat. No. 5,241,951 is relatively simple, rendering it less costly to manufacture and maintain and enabling greater ease of operation than the prior systems. The system of U.S. Pat. No. 5,241,951 consists essentially of a fluid reservoir, a submersible single-speed pump, a pad having an internal pad flowpath, inlet and outlet lines connecting the pad flowpath to the pump and a user adjustable in-line flow control valve. The system is operated by filling the reservoir with a non-ambient temperature treatment fluid and submersing the pump in the fluid. The pad is positioned on the desired treatment region of a patient and the pump is activated to deliver fresh treatment fluid from the reservoir to the pad flowpath via the inlet line and return spent treatment fluid from the pad flowpath to the reservoir via the outlet line. The patient regulates the treatment temperature of the pad by manually adjusting the flow control valve to control the flow rate of fluid through the pad flowpath.  
      The system of U.S. Pat. No. 5,241,951 has been shown to provide effective therapeutic treatment to the body. Nevertheless, it has been found that the patient is not always adept at properly adjusting the flow control valve to achieve a desired treatment temperature in the pad. In the case of low temperature treatment, if the patient sets the flow rate of the fluid through the pad too high, the pad may become too cold and harm the treatment region of the body. Conversely if the patient sets the flow rate too low, the pad may not become cold enough and the low temperature treatment will not be effective. In the case of high temperature treatment, if the patient sets the flow rate too high, the pad may become too hot, similarly harming the treatment region, while setting the flow rate too low, may similarly prevent the pad from becoming hot enough, rendering the high temperature treatment ineffective.  
      The present invention recognizes the need for an improved fluid circulation-type therapeutic treatment system employing a non-ambient temperature pad which obviates the need for user interface during operation while providing effective treatment of the patient. Accordingly, it is generally an object of the present invention to provide an improved non-ambient temperature therapy system, which is effective, safe and reliable. More particularly, it is an object of the present invention to provide such an improved non-ambient temperature therapy system, which automatically maintains the treatment temperature in the pad at a desired level in the absence of user interface. It is another object of the present invention to provide such an improved non-ambient temperature therapy system, which includes a family of pads, each pad having a different size or shape specific to a different application of the system. It is still another object of the present invention to provide such an improved non-ambient temperature therapy system, wherein all of the alternately sized or shaped pads of the pad family can be used interchangeably within the system in response to the desired application of the system. It is still another object of the present invention to provide such an improved non-ambient temperature therapy system, which enables substitution of any of the alternately sized or shaped pads for another within the system without disrupting the automatic treatment temperature maintenance function of the system. These objects and others are achieved in accordance with the invention described hereafter.  
     SUMMARY OF THE INVENTION  
      The present invention is a therapy system for therapeutically treating a desired region of the body which comprises a fluid reservoir, a heat transfer pad, first and second fluid circulation lines, and a pump. The fluid reservoir stores a charge of a heat transfer fluid at a non-ambient temperature. The heat transfer pad is conformable to a body region which has an ambient temperature and the non-ambient temperature of the heat transfer fluid is either a lower temperature or a higher temperature than the ambient temperature of the body region.  
      The heat transfer pad includes a first pad port, a bladder, and a second pad port, which define a pad flowpath extending in series therethrough. The first fluid circulation line is connectable to the first pad port and is in fluid communication with the fluid reservoir to withdraw the heat transfer fluid from the fluid reservoir and deliver the heat transfer fluid to the heat transfer pad via the first pad port. The second fluid circulation line is connectable to the second pad port and is in fluid communication with the fluid reservoir to withdraw the heat transfer fluid from the heat transfer pad via the second pad port and deliver the heat transfer fluid to the fluid reservoir. The first fluid circulation line, pad flowpath, and second fluid circulation line define a system flowpath extending in series therethrough.  
      The pump includes a motor fixed at a set operating speed which defines a maximum pump output. The pump is in fluid communication with the fluid reservoir and the first fluid circulation line to drive the heat transfer fluid through the system flowpath against a system resistance to flow. The pump preferably operates at an actual pump output less than the maximum pump output. The heat transfer pad additionally includes a pad flowpath adjustment member positioned in the pad flowpath, preferably mounted in the second pad port, which adjusts the system resistance to flow to an adjusted system resistance to flow. The adjusted system resistance to flow fixes a desired treatment temperature of the heat transfer pad in response to the heat transfer fluid circulating through the pad flowpath at a pad flow rate. The adjusted system resistance to flow is preferably greater than the system resistance to flow and the desired treatment temperature of the heat transfer pad is correlated to the body region being treated and is preferably indirectly correlated with the adjusted system resistance to flow.  
      In accordance with one embodiment, the pad flowpath adjustment member is a threaded rod positioned in the first or second pad port. In accordance with another embodiment, the pad flowpath adjustment member is a crimp formed in a wall of the first or second pad port. In accordance with yet another embodiment, the pad flowpath adjustment member is a plate or nozzle having an aperture formed therethrough positioned in the first or second pad port. In accordance with still another embodiment, the pad flowpath adjustment member is a tubing segment of the second pad port having a reduced cross-sectional area relative to the first pad port or the pad flowpath adjustment member is a tubing segment of the first pad port having a reduced cross-sectional area relative to the second pad port.  
      The present invention is alternately a therapy system for therapeutically treating a desired region of the body which comprises a fluid reservoir, a pad family, first and second fluid circulation lines, and a pump. The fluid reservoir, first and second fluid circulation lines and pump are all essentially as described above. The pad family includes a first and a second heat transfer pad. The first heat transfer pad has a first geometry and is conformable to a first body region having an ambient temperature. The first heat transfer pad includes a first pad port, a bladder, and a second pad port and defines a first pad flowpath extending in series therethrough. The second heat transfer pad has a second geometry different from the first geometry and is conformable to a second body region having the ambient temperature. The second heat transfer pad includes a first pad port, a bladder, and a second pad port and defines a second pad flowpath extending in series therethrough.  
      The first fluid circulation line is connectable to the respective first pad port of the first or second heat transfer pad and is in fluid communication with the fluid reservoir to withdraw the heat transfer fluid from the fluid reservoir and deliver the heat transfer fluid to the first or second heat transfer pad via the respective first pad port. The second fluid circulation line is connectable to the respective second pad port of the first or second heat transfer pad and is in fluid communication with the fluid reservoir to withdraw the heat transfer fluid from the first or second heat transfer pad via the respective second pad port and deliver the heat transfer fluid to the fluid reservoir. The first fluid circulation line, the first pad flowpath, and the second fluid circulation line define a first system flowpath extending in series therethrough. The first fluid circulation line, the second pad flowpath, and the second fluid circulation line alternately define a second system flowpath extending in series therethrough.  
      The pump is in fluid communication with the fluid reservoir and the first fluid circulation line to drive the heat transfer fluid through the first or second system flowpath against a system resistance to flow. A first pad flowpath adjustment member is positioned in the first pad flowpath, preferably mounted in the second pad port of the first heat transfer pad, which adjusts the system resistance to flow to a first adjusted system resistance to flow. The first adjusted system resistance to flow fixes a first desired treatment temperature of the first heat transfer pad in response to the heat transfer fluid circulating through the first pad flowpath at a first pad flow rate. The first desired treatment temperature is correlated to the first body region. A second pad flowpath adjustment member is positioned in the second pad flowpath, preferably mounted in the second pad port of the second heat transfer pad, to adjust the system resistance to flow to a second adjusted system resistance to flow. The second adjusted system resistance to flow fixes a second desired treatment temperature of the second heat transfer pad in response to the heat transfer fluid circulating through the second pad flowpath at a second pad flow rate. The second desired treatment temperature is correlated to the second body region.  
      In a preferred case, the second desired treatment temperature is less than the first desired treatment temperature. In accordance with this case, a preferred first body region is an ankle and a preferred second body region is a knee.  
      The present invention is alternately a method for therapeutically treating a desired region of the body with a non-ambient temperature treatment fluid. A charge of a heat transfer fluid is stored at a non-ambient temperature in a fluid reservoir. A heat transfer pad is positioned on a body region having an ambient temperature. The heat transfer pad includes a first pad port, a bladder, and a second pad port and defining a pad flowpath extending in series therethrough. A first fluid circulation line in fluid communication with the fluid reservoir is connected to the first pad port. The heat transfer fluid is withdrawn from the fluid reservoir via the first fluid circulation line and delivered to the heat transfer pad via the first pad port. A second fluid circulation line in fluid communication with the fluid reservoir is connected to the second pad port. The first fluid circulation line, pad flowpath, and second fluid circulation line define a system flowpath extending in series therethrough. The heat transfer fluid is withdrawn from the heat transfer pad via the second pad port and delivered to the fluid reservoir via the second fluid circulation line.  
      A pump in fluid communication with the fluid reservoir and the first fluid circulation line drives the heat transfer fluid through the system flowpath against a system resistance to flow. The pump includes a motor fixed at a set operating speed which defines a maximum pump output. A pad flowpath adjustment member is positioned in the pad flowpath, preferably mounted in the second pad port, which adjusts the system resistance to flow to an adjusted system resistance to flow. The adjusted system resistance to flow fixes a desired treatment temperature of the heat transfer pad in response to the heat transfer fluid circulating through the pad flowpath at a pad flow rate. The desired treatment temperature is correlated to the body region.  
      In accordance with a preferred embodiment, the body region is a first body region, the heat transfer pad is a first heat transfer pad, the pad flowpath is a first pad flowpath, the system flowpath is a first system flowpath, the pad flowpath adjustment member is a first pad flowpath adjustment member, the adjusted system resistance to flow is a first adjusted system resistance to flow, the desired treatment temperature is a first desired treatment temperature, and the pad flow rate is a first pad flow rate. The method further comprises positioning a second heat transfer pad on a second body region having the ambient temperature. The second heat transfer pad includes a first pad port, a bladder, and a second pad port and defines a second pad flowpath extending in series therethrough;  
      The first fluid circulation line is disconnected from the first pad port of the first heat transfer pad and the first fluid circulation line is reconnected to the first pad port of the second heat transfer pad. The heat transfer fluid is withdrawn from the fluid reservoir via the first fluid circulation line and the heat transfer fluid is delivered to the second heat transfer pad via the first pad port of the second heat transfer pad. The second fluid circulation line is disconnected from the second pad port of the second heat transfer pad and the second fluid circulation line is reconnected to the second pad port of the second heat transfer pad. The first fluid circulation line, second pad flowpath, and second fluid circulation line define a second system flowpath extending in series therethrough. The heat transfer fluid is withdrawn from the second heat transfer pad via the second pad port of the second heat transfer pad and the heat transfer fluid is delivered to the fluid reservoir via the second fluid circulation line.  
      The pump drives the heat transfer fluid through the second system flowpath against the system resistance to flow. A second pad flowpath adjustment member is positioned in the second pad flowpath, preferably mounted in the second pad port of the second heat transfer pad, to adjust the system resistance to flow to a second adjusted system resistance to flow. The second adjusted system resistance to flow fixes a second desired treatment temperature of the second heat transfer pad in response to the heat transfer fluid circulating through the second pad flowpath at a second pad flow rate. The second desired treatment temperature is correlated to the second body region.  
      In a preferred case, the non-ambient temperature is a lower temperature than the ambient temperature of the first and second body regions, the second adjusted resistance to flow is less than the first adjusted system resistance to flow, and the second desired treatment temperature is less than the first desired treatment temperature. In accordance with this case, a preferred first body region is an ankle and a preferred second body region is a knee.  
      The present invention will be further understood from the drawings and the following detailed description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is an exploded view of a non-ambient temperature therapy system of the present invention in a disassembled state.  
       FIG. 2  is a perspective view of the non-ambient temperature therapy system of  FIG. 1  in an assembled state, wherein the heat transfer pad of the system is operatively mounted on a patient.  
       FIG. 3  is a detailed plan view of the heat transfer pad included in the non-ambient temperature therapy system of  FIGS. 1 and 2 .  
       FIG. 4  is a cutaway side view of a pad flowpath adjustment member mounted in the flowpath of the heat transfer pad of  FIG. 3 .  
       FIG. 5  is a cutaway side view of an alternate embodiment of a pad flowpath adjustment member mounted in the flowpath of the heat transfer pad of  FIG. 3 .  
       FIG. 6  is a top view of the pad flowpath adjustment member of  FIG. 5 .  
       FIG. 7  is a cutaway side view of an alternate embodiment of a pad flowpath adjustment member mounted in the flowpath of the heat transfer pad of  FIG. 3 .  
       FIG. 8  is a top view of the pad flowpath adjustment member of  FIG. 7 .  
       FIG. 9  is a plan view of a pad family including a plurality of separate individual heat transfer pads, each having alternate utility in the non-ambient temperature therapy system of  FIGS. 1 and 2 . 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
      Referring initially to  FIG. 1 , a non-ambient temperature therapy system of the present invention is shown in a disassembled state and generally designated  10   a . The non-ambient temperature therapy system  10   a  comprises a heat transfer pad  12   a , a fluid reservoir  14 , a first fluid circulation line  16 , a second fluid circulation line  18 , and a pump  20 . Referring additionally to  FIG. 2 , the non-ambient temperature therapy system  10   a  is shown in an assembled state after a user has assembled the system  10   a  from the disassembled state. The user is typically a patient undergoing treatment with the non-ambient temperature therapy system  10   a  or a health care practitioner overseeing treatment of the patient with the system  10   a . The term “non-ambient temperature” is used herein relative to the ambient body temperature of the patient. A high temperature treatment applies a non-ambient treatment temperature to the body which is greater than the ambient body temperature while a low temperature treatment applies a non-ambient treatment temperature to the body which is less than the ambient body temperature.  
      When the non-ambient temperature therapy system  10   a  is in the assembled state shown in  FIG. 2 , the heat transfer pad  12   a  and the fluid reservoir  14  are positioned a distance apart from one another with the first and second fluid circulation lines  16 ,  18  extending in parallel between them. The first fluid circulation line  16  functions as a pad inlet line, withdrawing a fresh non-ambient temperature heat transfer fluid from the fluid reservoir  14  and delivering the fresh non-ambient temperature heat transfer fluid to the heat transfer pad  12   a  in accordance with a preferred method of operation described hereafter. Conversely, the second fluid circulation line  18  functions as a pad outlet line, withdrawing the spent heat transfer fluid from the heat transfer pad  12   a  and delivering the spent heat transfer fluid to the fluid reservoir  14 , likewise in accordance with the preferred method of operation described hereafter. The first and second fluid circulation lines  16 ,  18  are each preferably formed from a continuous length of identical flexible tubing each having the essentially same inside diameter.  
      An insulating line sheath  21  extends essentially the length of the first and second fluid circulation lines  16 ,  18  and covers the lines  16 ,  18 , thereby enclosing the lines  16 ,  18  within a single integrated smooth tubular unit (as shown in the cross-section blow-up). The line sheath  21  is formed in its entirety from a supple material which renders the line sheath  21 , in combination with the first and second fluid circulation lines  16 ,  18 , fully flexible. The line sheath  21  has a durable exterior skin and an insulating foam interior which minimizes heat transfer between the first fluid circulation line  16  and the second fluid circulation line  18  or between the first and second fluid circulation lines  16 ,  18  and the surrounding environment  28 . The line sheath  21  also prevents condensate formation on the exterior of the first and second fluid circulation lines  16 ,  18 .  
      The fluid reservoir  14  is a hollow fluid container, which includes means for a user to access the interior of the container, thereby enabling the user to manually add the non-ambient temperature heat transfer fluid in bulk to the fluid reservoir  14  when charging the non-ambient temperature therapy system  10   a  or to manually withdraw heat transfer fluid in bulk from the fluid reservoir  14  when draining the system  10   a . The fluid reservoir  14  is preferably a thermally-passive hollow fluid container having insulated walls  22  and a relatively wide accessible opening  24  at the top for addition or withdrawal of the heat transfer fluid. The preferred fluid reservoir  14  is additionally provided with a fitted removable lid  26 , which enables the user to selectively cover the opening  24 . Fitting the lid  26  across the opening  24  reduces the degree of heat transfer between the heat transfer fluid residing in the interior of the fluid reservoir  14  and the ambient atmosphere of the surrounding environment  28 . The preferred fluid reservoir  14  described above is essentially the same or similar to a conventional picnic or beverage cooler.  
      The term “thermally-passive”, as used herein, characterizes a structure which is free of any active structural cooling or heating elements, such as refrigeration coils, heating coils, or the like, which act on the heat transfer fluid to actively cool or heat the fluid. The entirety of the non-ambient temperature therapy system  10   a  is likewise preferably characterized as thermally-passive insofar as the system  10   a  in its entirety is preferably free of any active structural cooling or heating elements. Notwithstanding the above, it is within the scope of the present invention to place a passive cooling medium in the fluid reservoir  14 , such as ice or the like, to passively cool the heat transfer fluid therein.  
      Referring additionally to  FIG. 3 , the heat transfer pad  12   a  includes a first pad port  30   a  which preferably functions as an inlet port, a second pad port  32   a  which preferably functions as an outlet port, and a bladder  34   a  which is positioned between the first and second pad ports  30   a ,  32   a . The bladder  34   a  accommodates the first and second pad ports  30   a ,  32   a  and encloses a tortuous internal flowpath for the non-ambient temperature heat transfer fluid extending through the bladder  34   a  between the first and second pad ports  30   a ,  32   a . In accordance with a preferred embodiment, the bladder  34   a  is an essentially planar member formed from a shaped upper sheet of a thin flexible heat-conductive material, such as a pliable polyurethane film, which is laid over an essentially identically shaped and dimensioned lower sheet of the same material. The upper and lower sheets are sealingly bonded together along their entire periphery with the exception of two distinctly separate relatively short segments of the periphery, which are maintained unbonded to provide the first and second pad ports  30   a ,  32   a . The bladder  34   a  preferably has one or more flow diverters  36   a  integral therewith, which delineate the internal flowpath of the bladder  34   a  and enhance the tortuosity of the internal flowpath to facilitate distribution of the heat transfer fluid throughout the bladder  34   a . The flow diverters  36 a are preferably formed by periodically bonding the upper and lower sheets together at points interior to the periphery of the sheets.  
      Each first and second pad port  30   a ,  32   a  opens the internal flowpath of the bladder  34   a  to the surrounding environment  28 . The first and second pad ports  30   a ,  32   a  include first and second port couplings  38   a ,  40   a , which are positioned across the openings of the first and second pad ports  30   a ,  32   a , respectively. The first and second port couplings  38   a ,  40   a  are configured to cooperatively and releasably mate with first and second line couplings  42 ,  44 , respectively, which are included in the first and second fluid circulation lines  16 , 18 , respectively, and are positioned across the open proximal ends of the first and second fluid circulation lines  16 ,  18 . (The terms “proximal” and “distal” are used herein relative to the bladder  34   a .) The couplings  38   a ,  40   a ,  42 ,  44  are preferably snap-action locking couplings which are selectively manually releasable.  
      The first and second port couplings  38   a ,  40   a  are male couplings and the first and second line couplings  42 ,  44  are female couplings. Although not shown, the first and second port couplings  38   a ,  40   a  are alternatively configured as female couplings and the first and second line couplings  42 ,  44  are configured as male couplings. Mating the first port coupling  38   a  with the first line coupling  42  and the second port coupling  40   a  with the second line coupling  44  forms a connective joint  46  between the heat transfer pad  12   a  and first and second fluid circulation lines  16 ,  18 . The joint  46  provides fluid communication between the first and second pad ports  30   a ,  32   a  and the first and second fluid circulation lines  16 ,  18 , respectively, as well as between the first and second fluid circulation lines  16 ,  18  and the internal flowpath of the bladder  34   a  which is integral with the first and second pad ports  30   a ,  32   a .  
      In accordance with a preferred embodiment the first port coupling  38   a  and first line coupling  42  are uniquely and cooperatively configured so that the first port coupling  38   a  can only mate with the first line coupling  42  and not with the second line coupling  44 . The second port coupling  40   a  and second line coupling  44  are likewise uniquely and cooperatively configured so that the second port coupling  40   a  can only mate with the second line coupling  44  and not with the first line coupling  42 . As a result, the first pad port  30   a  can preferably only be coupled with the first fluid circulation line  16  and not with the second fluid circulation line  18 . The second pad port  32   a  can preferably only be coupled with the second fluid circulation line  18  and not with the first fluid circulation line  16 .  
      Each first and second port coupling  38   a ,  40   a  also includes an integral shutoff valve element which restricts access to the internal flowpath of the bladder  34   a  from the surrounding environment  28  via the first and second pad ports  30   a ,  32   a  when the first and second port couplings  38   a ,  40   a  are unmated. As such, the shutoff valve element is normally biased in the closed position by a cooperative biasing means, such as a spring or the like, when the first and second port couplings  38   a ,  40   a  are unmated. However, mating the first port coupling  38   a  with the first line coupling  42  and the second port coupling  40   a  with the second line coupling  44  brings the first and second line couplings  42 ,  44  into engagement with the shutoff valve element, thereby actively transitioning the shutoff valve element to the open position. When the shutoff valve element is in the open position, the shutoff valve element and associated biasing means do not substantially impede flow through the first and second port couplings  38   a ,  40   a.    
      Each first and second pad port  30   a ,  32   a  of the present embodiment further includes a relatively short tubing segment  48   a  which has a proximal end positioned at the periphery of the bladder  34   a  and a distal end extending away from the bladder  34   a . The proximal end of the short tubing segment  48   a  extends into the interior of the bladder  34   a  and is preferably fixably and permanently joined with the bladder  34   a  at the periphery. The proximal end is constructed to resist occlusion from kinking in the region where the proximal end is joined with the bladder  34   a . The first and second port couplings  38   a ,  40   a  are positioned across the open distal ends of the short tubing segments  48   a  of the first and second pad ports  30   a ,  32   a , respectively, and are likewise preferably fixably and permanently joined with the distal ends. The short tubing segments  48   a  facilitate connection of the first and second port couplings  38   a ,  40   a  with the first and second line couplings  42 ,  44  and extend the heat transfer pad  12   a  away from the joint  46  to shield the patient from the relatively rigid joint  46  during operation of the system  10   a . The short tubing segments  48   a  are preferably formed from the same flexible tubing and have essentially the same inside diameter as the first and second fluid circulation lines  16 ,  18 . An insulating port sheath  50   a (shown partially cut away) having a similar composition and construction to the line sheath  21  extends between the joint  46  and the heat transfer pad  12   a  and covers the short tubing segments  48   a.    
      Although not shown, the first and second pad ports  30   a ,  32   a  are alternatively configured with a relatively long tubing segment, which is substituted for the short tubing segment  48   a , thereby more distally positioning the first and second port couplings  38   a ,  40   a . In yet another alternative, the first and second pad ports  30   a ,  32   a  are configured without any tubing segments. In accordance with this alternative, the first and second port couplings  38   a ,  40   a  are positioned at the periphery of the bladder  34   a  and are permanently affixed directly to the bladder  34   a.    
      Heat transfer pads of the type having utility in the non-ambient temperature therapy system  10   a  are disclosed in commonly-owned U.S. Pat. Nos. 5,417,720 and 5,662,695 and U.S. Design Pats. Des. 348,106 and Des. 345,609, all of which are incorporated herein by reference. The heat transfer pads disclosed in the above-referenced patents and other like heat transfer pads having utility in the system  10   a  are commercially available from Breg, Inc., 2611 Commerce Way, Vista, Cailf. 92081, U.S.A. and are further disclosed at www.breg.com.  
      The pump  20  of the non-ambient temperature therapy system  10   a  is generally a means for driving the non-ambient temperature heat transfer fluid from the fluid reservoir  14  to the bladder  34   a  via the first fluid circulation line  16  and the first pad port  30   a . The pump  20  is further a means for circulating the non-ambient temperature heat transfer fluid through the internal flowpath of the bladder  34   a  and for driving the heat transfer fluid from the bladder  34   a  to the fluid reservoir  14  via the second pad port  32   a  and second fluid circulation line  18 .  
      The pump  20  of the non-ambient temperature therapy system  10   a  is not specific to any one structure or mechanism of operation, but can be selected from a number of pumps having differing structures and mechanisms of operation. For example, the pump  20  can inter alia be an axial pump, a centrifugal pump, a gear pump, or a reciprocating pump, each of which has its own distinct structure and mechanism of operation. Nevertheless, the pump  20  of the non-ambient temperature therapy system  10   a  is preferably operationally characterized as having a maximum pump output when the pump motor is at a set operating speed. Maximum pump output is defined herein as the fluid flow rate at the outlet of the pump when the pump motor is fixed at the set operating speed and the pump is pumping the given fluid against a minimal resistance to flow downstream of the pump. A minimal resistance to flow is typically experienced when the pump is only pumping against ambient atmospheric pressure at the pump outlet (i.e., essentially zero head pressure) and there are no other impediments to flow at or downstream of the pump outlet. A typical maximum pump output is on the order of about 200 ml/min.  
      The values of the set operating speed and maximum pump output are optimal values which often exceed actual values of pump operating parameters during system operation. In practice, the actual operating speed and actual pump output only match the set operating speed and maximum pump output, respectively, in the limited optimal case where there is minimal resistance to flow downstream of the pump. More commonly, there is an increased resistance to flow downstream of the pump exceeding the minimal resistance to flow, which causes a decrease in the actual operating speed of the pump motor below the set operating speed and a corresponding decrease in the actual pump output below the maximum pump output.  
      Thus, actual operating speed and correspondingly actual pump output are inversely correlated with resistance to flow of the system flowpath, within which the heat transfer fluid is circulated. In the case of the non-ambient temperature therapy system  10   a , the system flowpath is an essentially closed loop from the fluid reservoir  14  to the heat transfer pad  12   a  and back to the fluid reservoir  14 . A system designer specifies the pump  20  as a function of the system resistance to flow. In particular, a pump is selected for the non-ambient temperature therapy system  10   a  which includes a pump motor having sufficient power to drive the heat transfer fluid through the entire system flowpath at an acceptable flow rate (i.e., the actual pump output) against the system resistance to flow.  
      There are any number of ways for determining the system resistance to flow. Since the resistance to flow is correlated to the head pressure of the system and the pressure drop across the system, the system designer can calculate, measure, estimate, or otherwise determine the head pressure or pressure drop for the system as a whole or for individual components within the system flowpath and use this data to determine the system resistance to flow. An exemplary actual pump output is at least 100 ml/min at a head pressure of about 6.5 psi when the maximum pump output is 200 ml/min at a head pressure of about 0 psi.  
      A preferred pump satisfying the above-recited criteria is a pump having a single-speed pump motor. Such a pump is termed a single-speed pump and is defined herein as a pump having a pump motor which is permanently fixed at one set operating speed when pumping against a minimal downstream resistance to flow. The single-speed pump lacks means for the user to adjust or reset the set operating speed of the pump motor. As such, the set operating speed of the pump motor and correspondingly the maximum output of the single-speed pump are fixed by the manufacturer of the pump at the time of manufacture. Nevertheless, as noted above, the actual operating speed and actual pump output vary as a function of system resistance to flow.  
      An exemplary pump having utility in the system  10   a  is a single-speed submersible axial pump driven by a dc-powered electric motor, such as generally disclosed in U.S. Pat. No. 5,241,951, which is incorporated herein by reference. The system  10   a  employs a transformer  52  upstream of the pump  20  which converts ac power from a conventional ac wall outlet  54  to dc power. A power line  56  conveys the dc power from the transformer  52  to a dc motor in the pump  20 . The power line  56  is exposed as it extends between the transformer  52  and a power connector  58  mounted on the first and second fluid circulation lines  16 ,  18 . The power line  56  is enclosed within the line sheath  21  parallel to the first and second fluid circulation lines  16 ,  18  (shown in  FIG. 2 ) as the power line  56  extends from the power connector  58  to the pump  20 .  
      Alternatively, the dc-powered pump  20  obtains dc power directly from a dc power source, such as an automobile battery or a portable external or internal battery pack consisting of one or more disposable dry cell batteries or rechargeable batteries. In another alternative, the pump is driven by an ac-powered electric motor which is directly connected to the ac wall outlet  54 .  
      An alternate pump satisfying the above-recited criteria is a pump having a variable-speed pump motor. Such a pump is termed a variable-speed pump and is defined herein as a pump which includes means for the user to actively vary the set operating speed of the pump motor. If a variable-speed pump is employed in the non-ambient temperature therapy system  10   a  in accordance with the preferred method of operation described hereafter, the user fixes the set operating speed of the pump motor in correspondence with a desired maximum output before initiating operation of the system  10   a . Once operation of the system  10   a  is initiated, the user does not actively reset the set operating speed of the pump motor away from the initial set operating speed for the duration of the operating segment, which is defined as a time period when the system  10   a  is in continuous uninterrupted operation.  
      The distal ends of the first and second fluid circulation lines  16 ,  18  are attached to the pump  20  and open into an internal pumping chamber (not shown) of the pump  20 . The pumping chamber and correspondingly the distal ends of the first and second fluid circulation lines  16 ,  18  are open to the surrounding environment  28 . The pump  20  and distal ends of the first and second fluid circulation lines  16 ,  18  are operatively positioned in the interior of the fluid reservoir  14  when the non-ambient temperature therapy system  10   a  is in the assembled state, although the fluid reservoir  14  is not physically connected to (i.e., is structurally independent from) the pump  20  and the first and second fluid circulation lines  16 ,  18 . As a result, operative positioning of the pump  20  and distal ends of the first and second fluid circulation lines  16 ,  18  places the first and second fluid circulation lines  16 ,  18  in fluid communication with the interior of the fluid reservoir  14 . Although not shown, it is alternatively within the scope of the present invention to structurally integrate or otherwise physically connect the fluid reservoir  14  with the pump  20  and/or with the first and second fluid circulation lines  16 ,  18 .  
      The effectiveness of the non-ambient temperature therapy system  10   a  in treating a desired region of the body of a patient is largely dependent on the pad temperature which is termed herein the system treatment temperature (TTi 10 a). The treatment temperature is characterized as the surface temperature of the heat transfer pad  12   a  during system operation. There are a number of functional relationships between the treatment temperature and the system operating parameters. The functional relationship between the treatment temperature and the residence time of the heat transfer fluid in the pad (i.e, the pad residence time) is of particular interest. Specifically, the treatment temperature is directly correlated with the pad residence time for a low temperature treatment, while the treatment temperature is indirectly correlated with the pad residence time for a high temperature treatment.  
      The functional relationships between the resistance to flow of the system flowpath (i.e., the system resistance to flow) and the system operating parameters are also noteworthy. In particular, the system resistance to flow is indirectly correlated with the actual operating speed of the pump motor, the actual pump output, and the heat transfer fluid flow rate through the heat transfer pad  12   a  (i.e., the pad flow rate). Since the pad residence time is likewise indirectly correlated with the pad flow rate, it follows that the pad residence time is directly correlated with the system resistance to flow. Thus, the treatment temperature is directly correlated with the system resistance to flow during a low temperature treatment, i.e., the treatment temperature increases in response to an increase in the system resistance to flow and decreases in response to a decrease in the system resistance to flow. In contrast, the treatment temperature is indirectly correlated with the system resistance to flow during a high temperature treatment, i.e., the treatment temperature increases in response to a decrease in the system resistance to flow and decreases in response to an increase in the system resistance to flow. The present invention recognizes the above-recited functional relationship between treatment temperature and system resistance to flow. In practice, the present invention automatically imposes a desired treatment temperature on the non-ambient temperature therapy system  10   a  by employing a system flowpath configuration having a system resistance to flow which is specifically correlated with the desired treatment temperature.  
      The system flowpath, which circulates the heat transfer fluid from the fluid reservoir  14  to the heat transfer pad  12   a  and back to the fluid reservoir  14 , generally comprises in series the first fluid circulation line  16 , the heat transfer pad  12   a , and the second fluid circulation line  18 . The segment of the system flowpath extending through the heat transfer pad  12   a  is specifically termed the pad flowpath and comprises in series the first pad port  30   a , the internal flowpath of the bladder  34   a , and the second pad port  32   a . Each component of the system flowpath has a resistance to flow of the heat transfer fluid therethrough, which is a function of many variables relating to the fixed (i.e., inherent) physical geometry of the structural component, including interalia the length and inside diameter of the component and the smoothness and composition of the inside walls of the component. These resistances to flow are termed individual inherent resistances to flow.  
      The system flowpath has an overall system inherent resistance to flow (RTF 10a ), which is defined as the sum of the individual inherent resistances to flow of each component within the system flowpath. Thus, the system inherent resistance to flow is generally the sum of the individual inherent resistance to flow of the first fluid circulation line  16  (RTF 16 ), the individual inherent resistance to flow of the heat transfer pad (RTF 12a ), and the individual inherent resistance to flow of the second fluid circulation line  18  (RTF 18 ), wherein the individual inherent resistance to flow of the heat transfer pad (RTF 12a ) is the sum of the individual inherent resistance to flow of the first pad port (RTF 30a ), the individual inherent resistance to flow of the internal flowpath of the bladder  34   a  (RTF 34a ), and the individual inherent resistance to flow of the second pad port  32   a  (RTF 32a ).  
      The system inherent resistance to flow for the system flowpath is expressed by equations (1) and (2) below:
 
 RTF   10a   =RTF   16   +RTF   12a   +RTF   18 , wherein  (1)
 
 RTF   12a   =RTF   30a   +RTF   34a   +RTF   32a .  (2)
 
 It is apparent from equations (1) and (2) that the system inherent resistance to flow can be adjusted by modifying the configuration of any one or more components within the system flowpath, thereby modifying the individual resistance to flow of the reconfigured component and correspondingly modifying the system resistance to flow of the entire non-ambient temperature therapy system  10   a.  
 
      A preferred embodiment of the non-ambient temperature therapy system  10   a  is specific to low temperature treatment applications. In accordance with this embodiment, the non-ambient temperature therapy system  10   a  is provided with a pad flowpath adjustment member  60   a  which reconfigures the pad flowpath to increase the individual resistance to flow of the heat transfer fluid pad  12   a  and correspondingly to increase the overall system resistance to flow. As such, the non-ambient temperature therapy system  10   a  has a system adjusted resistance to flow (ARTF 10a ) which is greater than the system inherent resistance to flow (i.e., the resistance to flow of the system  10   a  in the absence of the pad flowpath adjustment member  60   a ). Inclusion of the pad flowpath adjustment member  60   a , which adjusts the resistance to flow of the non-ambient temperature therapy system  10   a , enables the system  10   a  to achieve a desired treatment temperature, which is greater than what the treatment temperature would otherwise be in the absence of the reconfigured pad flowpath. The degree to which the desired treatment temperature is increased is a function of the degree to which the system resistance to flow is increased by the pad flowpath adjustment member  60   a . Determination of this function is readily within the purview of the skilled artisan applying the teaching herein.  
      The pad flowpath adjustment member  60   a  is mounted in the pad flowpath of the heat transfer pad  12   a  and, more particularly, is mounted either in the internal flowpath of the bladder  34   a , in the first pad port  30   a  which includes the first port coupler  38   a , or in the second pad port  32   a  which includes the second port coupler  40   a . In a preferred embodiment, the pad flowpath adjustment member  60   a  is mounted in the second pad port  32   a . The term “mounted in” as used herein broadly encompasses one of the following alternatives: 1) positioning the pad flowpath adjustment member  60   a  internally within a component of the pad flowpath; serially attaching the pad flowpath adjustment member  60   a  to a component of the pad flowpath; or 3) integrating the pad flowpath adjustment member  60   a  into the construct of a component of the pad flowpath.  
      The pad flowpath adjustment member  60   a  is preferably an in-line passive device mounted in the first pad port  30   a  or second pad port  32   a  of the pad flowpath and most preferably in the second pad port  32   a . In any case, the pad flowpath adjustment member  60   a  is structurally distinct from the first or second pad port  30   a ,  32   a . The in-line passive device is inserted directly into the first or second pad port  30   a ,  32   a  (and most preferably in the second pad port  32   a ) to increase the resistance to flow of the pad flowpath and reduce the pad flow rate when the speed of the pump motor is fixed at the set operating speed and the pump  20  is correspondingly at the maximum pump output. The term “passive device” as used herein characterizes a device which is not user adjustable.  
      An exemplary passive device which functions as the pad flowpath adjustment member  60   a  is a baffle. The baffle redirects the heat transfer fluid as it passes through the pad flowpath past the baffle. A preferred baffle  60   a  is a threaded rod shown in  FIG. 4  which has a continuous screw thread  62  with multiple spiraled turns about a cylindrical core  64  in the manner of a conventional screw. The threaded rod  60   a  is coaxially positioned within the short tubing segment  48   a  of the first or second pad port  30   a ,  32   a  (and most preferably the second pad port  32   a  as shown in  FIG. 3 ). The thread  62  has an outside diameter which is essentially equal to the inside diameter of the short tubing segment  48   a  so that essentially all of the heat transfer fluid follows the spiral flowpath around the cylindrical core  64  of the threaded rod  60   a , while essentially none of the heat transfer fluid passes between the outer periphery of the thread  62  and the inner wall of the short tubing segment  48   a . Alternatively, the passive device  60   a  is a plate as shown in  FIGS. 5 and 6  or a nozzle as shown in  FIGS. 7 and 8 . The plate or nozzle  60   a  is positioned in the short-tubing segment  48   a  of the first or second pad port  30   a ,  32   a  (and most preferably the second pad port  32   a ) and each has an orifice  66  for fluid flow therethrough with a reduced cross-sectional area relative to the short tubing segment  48   a.    
      An example of a pad flowpath adjustment member  60   a  which is integrated into the construct of a component of the pad flowpath is a crimp formed in the wall of the short tubing segment  48   a  of the first or second pad port  30   a ,  32   a  (and most preferably in the second pad port  32   a ), which reduces the cross-sectional area of the short tubing segment  48   a  at the point of the crimp. An alternate integrated pad flowpath adjustment member  60   a  is provided by replacing all or a portion of the short tubing segment  48   a  of the first or second pad port  30   a ,  32   a  (and most preferably in the second pad port  32   a ) with a tubing segment having a reduced cross-sectional area relative to the remaining short tubing segment  48   a.    
      The system adjusted resistance to flow for the system flowpath of the system  10   a  (ARTF 10a ) is expressed by equations (3) and (4) below:
 
 ARTF   10a   =RTF   16   +ARTF   12a   +RTF   18 , wherein  (3)
 
 ARTF   12a   =ARTF   30a   +RTF   34a   +RTF   32a ;  (4a)
 
 ARTF   12a   =RTF   30a   +ARTF   34a   +RTF   32a ; or  (4b)
 
 ARTF   12a   =RTF   30a   +RTF   34a   +ARTF   32a .  (4c)
 
 Equation (4a) represents the case where the pad flowpath adjustment member  60   a  is mounted in the internal flowpath of the bladder  34   a , so that the bladder  34   a  has an adjusted resistance to flow (ARTF 34a ) which is great than the individual inherent resistance to flow of the bladder  34   a . Equation (4b) represents the case where the pad flowpath adjustment member  60   a  is mounted in the first pad port  30   a , so that the first pad port  30   a  has an adjusted resistance to flow (ARTF 30a ) which is great than the individual inherent resistance to flow of the first pad port  30   a . Equation (4c) represents the most preferred case where the pad flowpath adjustment member  60   a  is mounted in the second pad port  32   a , so that the second pad port  32   a  has an adjusted resistance to flow (ARTF 32a ) which is great than the individual inherent resistance to flow of the second pad port  32   a.  
 
      A system back pressure flow restrictor (not shown) is optionally mounted in-line along the length of the second fluid circulation line  18  downstream of the heat transfer pad  12   a  , although in many cases the pad flowpath adjustment member  60   a  obviates the need for the back pressure flow restrictor. In the event the system  10   a  lacks sufficient fluid back pressure downstream of the heat transfer pad  12   a , the optional back pressure flow restrictor creates sufficient fluid back pressure to maintain the bladder  34   a  properly inflated during the preferred method of operating the non-ambient temperature therapy system  10   a . The back pressure flow restrictor is an in-line passive device such as described or is alternately a variable in-line device such as the adjustable flow restrictor valve disclosed in U.S. Pat. No. 5,241,951. However, once operation of the system  10   a  is initiated, the user does not vary the variable back pressure flow restrictor away from the initial setting so that the individual inherent resistance to flow of the second fluid circulation line  18  remains constant for the entire operating segment.  
      Referring additionally to the  FIG. 9 , the heat transfer pad  12   a  of the non-ambient temperature therapy system  10   a  is optionally a member of a pad family generally designated  12 . In addition to the heat transfer pad  12   a , the pad family  12  comprises heat transfer pads  12   b ,  12   c ,  12   d . Each heat transfer pad  12   a ,  12   b ,  12   c ,  12   d  preferably has a substantially different geometry than the other, i.e., a different shape and/or one or more different dimensions of size, e.g., length, width, etc. The specific number of individual heat transfer pads and the specific geometry of each heat transfer pad shown in the particular pad family  12  of  FIG. 9  are selected solely for purposes of illustration and are not intended to limit the present invention. In practice the pad family  12  can comprise essentially any number of individual heat transfer pads and each individual heat transfer pad can have essentially any geometry within the limits of practicality.  
      It is apparent from  FIG. 2  that the non-ambient temperature therapy system of the present invention can accommodate only one heat transfer pad from the pad family  12  at any given time in the assembled state.  FIGS. 1 and 2  illustrate one embodiment of the non-ambient temperature therapy system, wherein the system  10   a  includes the heat transfer pad  12   a . It is alternately within the scope of the present invention to substitute any one of the remaining heat transfer pads  12   b ,  12   c , or  12   d  in the pad family  12  for the heat transfer pad  12   a  at the discretion of a user when assembling the non-ambient temperature therapy system. Thus, an alternate embodiment of the non-ambient temperature therapy system substitutes the heat transfer pad  12   b  for the heat transfer pad  12   a . The resulting system referred to hereafter as  10   b  (although not shown) comprises the same fluid reservoir  14 , first and second fluid circulation lines  16 ,  18  and pump  20  as the system  10   a  as well as the different heat transfer pad  12   b . Another alternate embodiment of the non-ambient temperature therapy system referred to as  10   c  (not shown) differs from the system  10   a  only in the substitution of the heat transfer pad  12   c  for the heat transfer pad  12   a . Still another alternate embodiment of the non-ambient temperature therapy system referred to as  10   d  (not shown) differs from the system  10   a  only in the substitution of the heat transfer pad  12   d  for the heat transfer pad  12   a.    
      The description of the non-ambient temperature therapy system  10   a  recited above applies generally to each of the remaining alternate non-ambient temperature therapy systems  10   b ,  10   c ,  10   d , except for the differences between the particular heat transfer pads  12   a ,  12   b ,  12   c , or  12   d  employed therein. Furthermore, the general construction of all the heat transfer pads  12   a ,  12   b ,  12   c ,  12   d  in the pad family  12  is preferably essentially the same apart from apparent differences in the geometry of the individual heat transfer pads. As such, the construction of the heat transfer pad  12   a  described above applies generally to each of the remaining heat transfer pads  12   b ,  12   c ,  12   d  in the pad family  12 . Although the heat transfer pads  12   a ,  12   b ,  12   c ,  12   d  all have different geometries, their individual inherent resistances to flow are all essentially equal to one another and each exhibits essentially the same heat transfer rate between the heat transfer pad and the body of a patient for a given area of the heat transfer pad.  
      The overall system inherent resistance to flow for the system flowpath of each system  10   b ,  10   c ,  10   d  (RTF 10b , RTF 10c , RTF 10d ) and their relation to one another and system  10   a  is expressed by equations (5)-(11) below:
 
 RTF   10b   =RTF   16   +RTF   12b   +RTF   18 , wherein  (5)
 
 RTF   12b   =RTF   30b   +RTF   34b   +RTF   32b   (6)
 
 RTF   10c   =RTF   16   +RTF   12c   +RTF   18 , wherein  (7)
 
 RTF   12c   =RTF   30c   +RTF   34c   +RTF   32c   (8)
 
 RTF   10d   =RTF   16   +RTF   12d   +RTF   18 , wherein  (9)
 
 RTF   12d   =RTF   30d   +RTF   34d   +RTF   32d   (10)
 
 RTF   10a   =RTF   10b   =RTF   10d   =RTF   10d   (11)
 
      As with the heat transfer pad  12   a , the remaining heat transfer pads  12   b ,  12   c ,  12   d  in the pad family  12  are each preferably provided with a pad flowpath adjustment member  60   b , a pad flowpath adjustment member  60   c , and a pad flowpath adjustment member  60   d , respectively (none are shown). As in the case of the pad flowpath adjustment member  60   a , the pad flowpath adjustment member  60   b  provides the system  10   b  with a system adjusted resistance to flow (ARTF 10   b ), the pad flowpath adjustment member  60   c  provides the system  10   c  with a system adjusted resistance to flow (ARTF 10c ), and the pad flowpath adjustment member  60   d  provides the system  10   d  with a system adjusted resistance to flow (ARTF 10d ). The pad flowpath adjustment members  60   b ,  60   c ,  60   d  all have an essentially similar construction to pad flowpath adjustment member  60   a  described above although two or more of the pad flowpath adjustment members may have different individual resistances to flow as described below.  
      The system adjusted resistance to flow for the system flowpath of each alternate system  10   b ,  10   c ,  10   d  is expressed by equations (12)-(17) below:
 
 ARTF   10b   =RTF   16   +ARTF   12b   +RTF   18 , wherein  (12)
 
 ARTF   12b   =ARTF   30b   +RTF   34b   +RTF   32b ;  (13a)
 
 ARTF   12b   =RTF   30b   +ARTF   34b   +RTF   32b ; or   (13b)
 
 ARTF   12b   =RTF   30b   +RTF   34b   +ARTF   32b .  (13c)
 
 ARTF   10c   =RTF   16   +ARTF   12c   +RTF   18 , wherein  (14)
 
 ARTF   12c   =ARTF   30c   +RTF   34   +RTF   32c ;  (15a)
 
 ARTF   12c   =RTF   30c   +ARTF   34c   +RTF   32c ; or  (15b)
 
 ARTF   12c   =RTF   30c   +RTF   34   +ARTF   32c ,  (15c)
 
 ARTF   10d   =RTF   16   +ARTF   12d   +RTF   18 , wherein  (16)
 
 ARTF   12d   =ARTF   30d   +RTF   34d   +RTF   32d ; or  (17a)
 
 ARTF   12d =RTF 30d   +ARTF   34d   +RTF   32d ; or  (17b)
 
 ARTF   12d   =RTF   30d   +RTF   34d   +ARTF   32d .  (17c)
 
      In accordance with one embodiment of the present invention, the pad flowpath adjustment members are selected such that each pad flowpath adjustment member  60   a ,  60   b ,  60   c ,  60   d  imparts an adjusted resistance to flow to its respective heat transfer pad  12   a ,  12   b ,  12   c ,  12   d  which is different than one or more of the other heat transfer pads. Since the non-ambient temperature therapy systems  10   a ,  10   b ,  10   c ,  10   d  are essentially identical in all other respects, the system adjusted resistance to flow of each non-ambient temperature therapy system  10   a ,  10   b ,  10   c ,  10   d  differs from the others only as a function of the respective pad flowpath adjustment members  60   a ,  60   b ,  60   c ,  60   d . Accordingly, the system designer pairs the pad flowpath adjustment members with the heat transfer pads such that each heat transfer pad imparts a fixed predetermined system adjusted resistance to flow and correspondingly a fixed desired treatment temperature to its respective assembled system. Consequently, each non-ambient temperature therapy system provides a desired treatment temperature during system operation which is specific to its respective heat transfer pad. In particular, the system  10   a  provides the fixed desired treatment temperature (TT 10a ), the system  10   b  provides the fixed desired treatment temperature (TT 10b ), the system  10   c  provides the fixed desired treatment temperature (TT 10c ), and the system  10   d  provides the fixed desired treatment temperature (TT 10d ). Some or all of the above-recited fixed desired treatment temperatures are preferably different from one another.  
      The geometry of each heat transfer pad  12   a ,  12   b ,  12   c ,  12   d  is often dictated by the shape of a particular region of the body being treated so that the heat transfer pad exhibits close-fitting conformance to the contours of the specified region. For example, the heat transfer pad  12   a  is designed to conform to the knee or shoulder, the heat transfer pad  12   b  is designed to conform to the ankle, the heat transfer pad  12   c  is designed to conform to the back, while the heat transfer pad  12   d  is designed for general conformance to non-specific regions of the body. The desired treatment temperature is also dictated by the region of the body patient being treated because certain regions of the body are more sensitive and less able to withstand non-ambient temperature extremes than other regions. For example, the desired treatment temperature for the knee or shoulder is generally lower than the desired treatment temperature for the ankle during a low temperature treatment.  
      In view of the above, the system designer specifies a pad flowpath adjustment member  60   a  for mounting in the heat transfer pad  12   a  specific to knee or shoulder treatment applications which has a relatively low resistance to flow, thereby achieving a lower system adjusted resistance to flow and effecting a lower desired treatment temperature. In contrast, the system designer specifies a pad flowpath adjustment member  60   b  for mounting in the heat transfer pad  12   b  specific to ankle treatment applications which has a relatively high resistance to flow, thereby achieving a higher system adjusted resistance to flow and effecting a higher desired treatment temperature. In any case, the desired treatment temperature is preferably in a range of about 45 to 55° F. for a low temperature treatment.  
      The relations between the above-recited parameters for the systems  10   a ,  10   c  in accordance with the present example are expressed by the equations (18) and (19) below:
 
ARTF 10a &lt;ARTF 10c   ( 18 )
 
TT 12a &lt;TT 12c   ( 19 )
 
 In sum, the individual adjusted resistances to flow of the heat transfer pads  12   a ,  12   b ,  12   c ,  12   d  and correspondingly the system adjusted resistances to flow and the desired treatment temperatures of the non-ambient temperature therapy systems  10   a ,  10   b ,  10   c ,  10   d  are fixed to correspond with the specific requirements of the desired treatment application. 
 
     Method of Operation  
      An embodiment of a method of operating the non-ambient temperature therapy system  10   a  is described hereafter with further reference to the drawings. It is understood that the operating method described hereafter applies generally to operation of the non-ambient temperature therapy systems  10   b ,  10   c ,  10   d  as well. The method is initiated by a series of set-up steps, wherein the heat transfer pad  12   a  is selected by the user as a function of the desired treatment application for a knee or shoulder treatment application. The heat transfer pad  12   a  is then mounted on the skin of the desired body region of the patient where non-ambient temperature treatment is desired, which in the present case is the knee  68 . An additional thin padding material, such as a soft cloth, may be placed on the skin between the bladder  34   a  and the skin for the comfort of the patient.  
      Mounting the heat transfer pad  12   a  on the knee  68  is typically effected by wraps (not shown) which are permanently attached to the heat transfer pad  12   a  or which are separately provided. The configuration of the heat transfer pad  12   a  renders it readily and fully conformable to the contours of the knee  68  of the patient on which it is mounted. A plurality of slits  70  are formed in the heat transfer pad  12   a  which enhance conformance to the knee  68 . The configuration of the heat transfer pad  12   a  enables a large fraction of the pad surface area to contact the knee  68  and advantageously facilitates heat transfer between the heat transfer pad  12   a  and the knee  68 .  
      A charge of heat transfer fluid is placed in the fluid reservoir  14  via the opening  24 . The heat transfer fluid is preferably a liquid and the volume of the heat transfer fluid charge is preferably several times the volume of the heat transfer pad  12   a . A preferred heat transfer fluid for a low temperature treatment is cold water. Solid ice can also be charged to the fluid reservoir  14  with the cold water to produce ice water for the low temperature treatment. A preferred heat transfer fluid for a high temperature treatment is hot water. The charged fluid reservoir  14  is positioned proximal the patient and the pump  20  is submersed in the heat transfer fluid within the fluid reservoir  14 . The lid  26  is placed over the opening  24  with the first and second circulation lines  16 ,  18  extending from the fluid reservoir  14 . The power line  56  of the pump  20  is connected to a source of electrical power. Once the heat transfer pad  12   a  is mounted on the knee  68  and the pump  20  is operatively positioned, the couplings  38   a  and  42  and the couplings  40   a  and  44 , respectively, are locked together to close the joint  46  and complete the set-up steps. The resulting non-ambient temperature therapy system  10   a  is in an assembled state and in a condition for operation.  
      Operation of the system  10   a  is initiated by powering up the pump  20 , preferably by means of an on/off power switch (not shown) mounted on the power connector  58  or simply by connecting the power line  56  with the wall outlet  54  and the power connector  58 . The pump  20  withdraws the heat transfer fluid from the fluid reservoir  14  and drives the fluid through the first fluid circulation line  16  into the heat transfer pad  12   a , thereby inflating the bladder  34   a . The pump  20  circulates the heat transfer fluid through the internal flowpath of the bladder  34   a , causing the temperature of the heat transfer pad  12   a  to drop to the desired treatment temperature in the case of a low temperature treatment and in turn causing the transfer of body heat from the patient to the pad  12   a  by a heat transfer mechanism. In the case of a high temperature treatment, the heat transfer fluid causes the temperature of the heat transfer pad  12   a  to rise to the desired treatment temperature and in turn causes heat to be transferred from the pad  12   a  to the body of the patient by a heat transfer mechanism.  
      In either case, the heat transfer fluid is withdrawn from the heat transfer pad  12   a  after circulating therethrough and is returned to the fluid reservoir  14 . The withdrawn heat transfer fluid mixes with the relatively large volume of heat transfer fluid remaining in the heat transfer reservoir  14 , which functions as a heat sink, essentially reversing any temperature increase or decrease in the withdrawn heat transfer fluid due to heat transfer with the body. The pump  20  is operated continuously as long as treatment is desired, thereby providing continuous steady-state circulation of the heat transfer fluid between the fluid reservoir  14  and heat transfer pad  12   a  for the duration of the treatment. Operation of the system  10   a  is terminated by simply shutting off the electrical power to the pump  20 .  
      While the forgoing preferred embodiments of the invention have been described and shown, it is understood that alternatives and modifications, such as those suggested and others, may be made thereto and fall within the scope of the invention.