Patent ID: 12193968

DETAILED DESCRIPTION

One embodiment of a medical pad10for contact and thermal exchange with a skin region of a patient is illustrated inFIGS.1-4. As shown inFIG.1, the pad10may include an inlet port16aand an outlet port16bfor circulating a thermal exchange fluid (e.g. a liquid such as water) in to and out of a fluid circulation layer of the pad10. For such purposes, the inlet port12aand outlet port12bmay have corresponding first ends that fluidly communicate with the fluid containing layer of the pad10, respectively. The inlet port12aand outlet port12bmay further include corresponding second ends that extend laterally outside of the fluid containing layer in a common direction. As illustrated, the second ends of inlet port12aand outlet port12bmay be provided for fixed interconnection with fluid circulation lines40aand40b, respectively. In one approach, the fluid circulation lines40aand40bmay be defined by lengths of flexible tubing. The fluid circulation lines40a,40bmay be provided with a connector42for use in selective interconnection to and disconnection from a fluid conditioning assembly, wherein a thermal exchange fluid may be circulated through the pad10, as will be further described hereinbelow.

As best illustrated inFIGS.2-4, the pad10may include a flexible base member14and a flexible film layer15that are interconnected to define the fluid circulation layer of pad10, wherein the fluid circulation layer has an internal volume between the base member14and film layer15. Further, pad10may comprise a flexible hydrogel layer16interconnected to the film layer15. As will be further described, the hydrogel layer16provides for thermal conduction between the circulated thermal exchange fluid and a patient, and further presents an adhesive surface16ato establish and maintain intimate contact with a skin region of a patient so as to optimize thermal exchange. The hydrogel layer may extend across a portion, a majority, or substantially the entirety of one side of the fluid circulation layer.

A removable liner layer17may be provided to cover the adhesive surface16aprior to use. Further, an optional outer layer18may be provided on another side of the fluid containing layer.

As illustrated inFIGS.2and4, the base member14may have two sets of one or more holes14cextending therethrough, wherein one set is disposed in aligned relation with inlet port12aand the other set is disposed in aligned relation with outlet port12b. Similarly, optional layer18may have two sets of one or more holes18cextending therethrough, wherein one set is disposed in aligned relation with inlet port12aand the other set is disposed in aligned relation with outlet port12b. In turn, circulated fluid may flow from inlet port12athrough the first sets of the holes and into the fluid circulation layer, then out of the fluid containment layer via the second sets of holes and outlet port12b.

As shown inFIGS.2and4, the fluid circulation layer may comprise one or a plurality of fluid channels to direct fluid flow between the inlet port12aand outlet port12b. In that regard, the base member14may include one or a plurality of rib members14athat project from a base portion14dand are interconnected to the film layer15. The fluid channels may extend between adjacent rib members14aand/or between sealed edges of the pad10and/or between rib members14aand sealed edges of the pad10.

The fluid channels may be configured to provide for fluid flow across the lateral extent of the pad10. In some embodiments, the inlet port12aand fluid channels may be spaced to define a staging region within the fluid containing layer that is adjacent to and fluidly interconnected to a first end of each of a plurality of channels. Further, the outlet port12band fluid channels may be spaced to define another staging region within the fluid containing layer that is adjacent to and fluidly interconnected to a second end of each of a plurality of channels.

The rib members14amay be provided to project from the base portion14da distance that defines a geometric height, or thickness, of the internal volume of the fluid circulation layer. As may be appreciated, the rib members14amay be provided to not only define fluid channels but also to support the film layer15.

In the later regard, the base member14may also comprise a plurality of offset projections14bthat project from the base portion14da distance that is substantially the same or different from the projection distance of rib members14a. In contemplated arrangements, the rib members14aand projections14ball may projection the same distance from base portion14d, wherein the common distance is between about 0.06″ to 0.10″ from base portion14d. As such, an internal volume having a geometric height, or thickness, of between about 0.06″ and 0.10″ is provided. In turn, medical pad applications where fluid is circulated, or drawn, through the fluid circulation layer at a negative pressure, the fluid containing layer may maintain an effective internal volume height of at least between about 0.04″ and 0.08″ during circulated fluid flow therethrough. In short, the rib members14aand projections14bmay be provided to supportably engage the film layer15to define and maintain fluid flow passageways through the fluid circulation layer by keeping the film layer15from collapsing across the base member14.

The hydrogel layer16may comprise an ultra violet light-cured composition that includes a cross-linking copolymer in an amount between about 15% to 30% by weight of the composition, and preferably in an amount between about 25% to 30% by weight of the composition; water in an amount between about 15% to 40% by weight of the composition, and preferably in an amount of between about 25% to 35% by weight of the composition; and glycerol in an amount between about 25% to 35% by weight of the composition, and preferably in an amount of between about 27.5% to 32.5% by weight of the composition. Further, the composition may comprise potassium chloride, e.g. in an amount between about 1.75% to 2.25% by weight of the composition, and/or (poly)vinyl pyrrolidone, e.g. in an amount between about 1.25% to 1.75% by weight of the composition.

In one implementation, the hydrogel layer16may comprise an ultraviolet light-cured composition having a formulation as set forth in Table 1 below.

TABLE 1MaterialPercentage by WeightGlycerin30 ± .25%Water34 ± .25%NaAMPS*/AA co-polymer28 ± .25%Potassium chloride2 ± .25%(Poly)vinyl pyrrolidone1.5 ± .25%*AMPS is a trademark of The Lubrizol Corporation

In such formulation, the cross-linking copolymer comprises sodium 2-acyrylamido-2-methylpropanesulfonate and acrylic acid.

In contemplated embodiments, the hydrogel layer16may be provided to have a thermal conductivity of at least about 1.9 cal/hr-cm-° C., and preferably between about 1.9 cal/hr-cm-° C. and 2.37 cal/hr-cm-° C. Further, in various arrangements film layer15may be provided to have a thermal conductivity of between about 3.44 cal/hr-cm-° C. and 4.3 cal/hr-cm-° C.

In some implementations, the adhesive surface of the hydrogel layer may have a tack strength of between about 20 g and 65 g, as determined according to ISO 9665:1998(E).

In contemplated embodiments, the hydrogel layer may have a thickness of between about 0.018″ and 0.04″. More particularly, the hydrogel layer may have a thickness of between about 0.022″ and 0.032″.

In some implementations, the base member14may be defined by a closed foam material (e.g. a polymer foam material) that is heat pressed to form the rib members14aand projections14b. The film layer15may comprise a heat activatable film (e.g. a polymer material) that may be sealably bonded via a heat lamination process about its periphery to the periphery of the base member14. Further, the heat lamination process may bond the film layer15to interfacing top surfaces of the rib members14a, and optionally to interfacing top surfaces of the projections14b.

In some embodiments, the removable liner layer17may be provided to peel away from adhesive surface16a. In that regard, successive portions of the liner layer17may be pulled away from adhesive surface16ato allow for successive adhesive positioning of different portions of adhesive surface16aat a patient skin region.

FIG.5schematically illustrates one embodiment of a system1for patient temperature control. The system1may include a controller50for providing output signal52for use in the operation of a fluid conditioning assembly20, so as to cool, optionally warm, and circulate thermal exchange fluid through one or more medical pad(s)10.

The fluid conditioning assembly20may include a fluid pump21for circulating the thermal exchange fluid to a heat exchanger23for passage to a fluid coupling interface30and pad(s)10. In one implementation, the controller50, fluid conditioning assembly20, and fluid coupling interface30may be supportably interconnected to a first support structure100.

As noted, controller50may provide output signals for use in the operation of fluid conditioning assembly20. More particularly, output signals52may include a signal for use in controlling the speed and/or duty cycle of the fluid pump21and a signal for controlling a cooling rate of the heat exchanger23, and optionally, for controlling a warming rate of the heat exchanger23. For example, the output signals52may include a signal for controlling a duty cycle of heat exchanger23and/or for controlling a magnitude of fluid thermal exchange provided by heat exchanger per time unit of operation.

In turn, the output signals52may be provided to control thermal exchange between the circulated fluid and a patient P via pad(s)10. For example, the rate of thermal exchange between the circulated fluid and the patient P may be controlled so as to achieve a desired degree of patient temperature cooling for induced hypothermia and optional patient temperature warming to achieve normothermia.

To generate the output signals52, the controller50may be provided to utilize one or a number of signals provided by one or more sensors comprising system1. In particular, system1may include at least a first fluid temperature sensor24for sensing a temperature of the circulated fluid and providing a first fluid temperature signal25indicative thereof to controller10. The first fluid temperature sensor24may be provided as part of the fluid conditioning assembly20and disposed to sense a temperature of the circulated fluid to be supplied through fluid coupling interface30to pad(s)10. Additionally, controller10may be further provided to receive a patient temperature signal82from a patient temperature sensor80, wherein the patient temperature signal is indicative of a sensed temperature of a patient P (e.g., a patient core body temperature).

Optionally, the fluid conditioning system20may also include a flow meter sensor22for measuring a flow rate of the circulated fluid (e.g., between the pump21and heat exchanger22) and providing a flow rate signal26indicative thereof to controller10, and a second fluid temperature sensor (not shown inFIG.1) for sensing a temperature of the circulated fluid returning from thermal exchange module40(e.g., upstream of pump21) and providing a second fluid temperature signal indicative thereof to controller10. The flow rate signal26and/or second fluid temperature signal may also be utilized by controller10to generate one or more of the output signals12a.

As shown, the fluid coupling interface30may be provided for selective fluid interconnection with one or more medical pad(s)10that may be utilized for thermal exchange with a patient P. For purposes of fluidly interconnecting fluid circulation lines40a,40bwith fluid conditioning assembly20, the connecter42may be configured for selective connection to and disconnection from a compatible connecter70provided on a reusable hose assembly that is interconnectable to and disconnectable from fluid at interface30. In that regard, connectors may be employed as taught in U.S. Pat. No. 6,802,855, hereby incorporated by reference in its entirety.

FIG.6illustrates an embodiment of a fluid conditioning assembly20for use in the system embodiment ofFIG.5. As shown, fluid conditioning assembly20includes fluid pump21for pumping fluid through a flow meter22in to heat exchanger23. Upon operation of fluid pump21, fluid may be drawn from heat exchanger23through outlet line27, through an outlet port34of fluid coupling interface30, through the fluidly interconnected medical pad(s)10, through inlet port33of fluid coupling interface30, and through inlet line28. As may be appreciated, the described operation may advantageously establish a negative pressure in medical pad(s)10to draw the circulated fluid therethrough. By way of example, a negative pressure of between about −0.5 psi and −10 psi may be provided.

Heat exchanger23may include a circulation tank210to receive the circulated fluid from fluid pump21. In order to provide for an adequate amount of fluid, heat exchanger23may also optionally include a supply tank214for containing fluid that may flow into circulation tank210as needed in order to maintain a predetermined minimum amount of fluid in circulation tank210for flow in the described arrangement.

Heat exchanger23may further include a chiller tank212and a mixing pump230for pumping fluid from within circulation tank210into chiller tank212. Additionally, heat exchanger23may include a chiller pump232and an evaporator/chiller234, wherein upon operation of chiller pump233fluid may be pumped from chiller tank212through evaporator/chiller234and back into chiller tank212to yield cooling of fluid within chiller tank212. In turn, fluid contained within chiller tank212may flow back into circulation tank210(e.g., by flowing over a barrier), wherein the fluid contained in circulation tank210may be cooled to a desired temperature via operation of mixing pump230, chiller pump232, and evaporator/chiller234.

In that regard, operation of mixing pump230, chiller pump232, and evaporator/chiller234may be controlled by the output signals52of controller50. As described above, the output signals52may be generated by controller50utilizing the first temperature signal25provided by first temperature sensor24. As shown inFIG.6the first temperature sensor24may be located to sense the temperature of the fluid in circulation tank210.

As further shown inFIG.6, a second fluid temperature sensor26may be provided downstream of inlet port33to sense the temperature of the circulated fluid that is returned from the pad(s)10. The second fluid temperature sensor26may provide a second temperature signal to controller50indicative of the sensed temperature for use in generation of output signals52. Further, a third fluid temperature sensor227may be provided to sense the temperature of fluid within chiller tank212and provide a third temperature signal indicative of the sensed temperature. In turn, the third temperature signal may be utilized by controller50to generate output signals52.

To provide redundancy in relation to the first fluid temperature sensor24, a fourth fluid temperature sensor228may also be provided within circulation tank210to provide a fourth temperature signal indicative of the sensed temperature for redundant potential usage by controller50in generating output signals52.

In the arrangement illustrated inFIG.6, a fluid pressure sensor28may also be provided to sense the pressure of the circulated fluid returning from medical pad(s)10. In turn, the pressure sensor28may provide a pressure signal to controller50indicative of the sensed pressure. In turn, controller50may utilize the pressure signal to generate output signals52provided to fluid pump21, e.g., to control the speed of fluid pump21to provide for a desired negative pressure within the medical pad(s)10.

With further reference toFIG.6, heat exchanger23may include a heater229for selective heating of the fluid contained in circulation tank210. In that regard, heater229may be provided to receive output signals52from controller50to provide a desired degree of heating to the fluid in circulation tank210. As may be appreciated, operation of heater229may be utilized to heat the circulated fluid so as to effect patient rewarming in various embodiments.

FIG.7illustrates one embodiment of a controller50. The controller50may be computer-based (e.g., a microprocessor) and may include a programmable control module120and a user interface110for receiving user control input and for providing corresponding signals112to the programmable control module120. User interface110may be further adapted to receive signals114from the programmable control module120for use in the display of control and measured data and for operative, interactive interface with a user at user interface110.

The programmable control module120may be provided to store control data (e.g., via a computer readable medium) and generate signals in corresponding relation to a plurality of different temperature control phases. In that regard, the programmable control module may comprise control logic for utilizing the control data to provide output signals to the heat exchanger23and/or the fluid pump21, wherein the temperature of the circulated fluid is controlled in a predetermined manner for each of the plurality of different temperature control phases.

Additionally or alternatively, the programmable control module120may be provided to facilitate the establishment of one or more programmed protocols that each comprise control data for use in the control of each of the plurality of temperature control phases. By way of example, a given protocol may comprise control data that includes target patient temperature data for each of a plurality of treatment phases. Further, for one or more of the phases, the protocol may comprise control data comprising a set duration for thermal treatment. As may be appreciated, the user interface110may be adapted for use in receiving user input to establish the control data corresponding with each of the plurality of different patient temperature control phases on a protocol-specific basis.

For each given protocol the programmable control module120may provide output signals52to at least the heat exchanger23, and optionally to fluid pump21, on a phase-specific basis. In turn, thermal exchanger23may be provided to responsively change the temperature of the circulated fluid to affect a desired thermal exchange with a patient, e.g., to cool, maintain the temperature of, or warm a patient via contact thermal exchange via contact pad(s)90. For example, and as noted above, heat exchanger23may comprise various componentry which operate to change the temperature of the circulated fluid in corresponding relation to control signals52output from the programmable control module120.

As discussed above, system1may comprise a first fluid temperature sensor24for sensing the temperature of the circulated fluid on an ongoing basis and providing a corresponding first fluid temperature signal25to the controller50. Further, patient temperature sensor80may be provided to sense the temperature of the patient P on an ongoing basis and provide corresponding signal82to the controller50. In turn, the signals may be employed by the programmable control module120, together with control data and preset algorithms, to generate (e.g., via the processor logic) the control signals52provided to heat exchanger23, so as to yield the desired temperature of the circulated fluid (e.g., on a single phase or phase specific basis).

In one approach, the control data for a first phase of the plurality of different control phases may be established so that, during the first phase, the circulated fluid may be cooled to so that the patient reaches an established target patient temperature (e.g., corresponding with induced hypothermia). For such purposes, the controller50may utilize a patient temperature signal82as referenced above to determine whether or not and when a patient has reached the established target patient temperature (e.g., by comparison of the corresponding patient temperature to the established target patient temperature) and to provide output signals52to the heat exchanger23and/or fluid pump21responsive thereto. In one implementation, the circulated fluid may be cooled at a predetermined rate (e.g., a predetermined maximum rate) to cool a patient to the established target patient temperature as rapidly as possible (e.g., within predetermined system limits).

Optionally, the control data for the first phase of the plurality of different control phases may further comprise an established duration measure, wherein once the established target patient temperature is reached the patient is maintained at the established target patient temperature for any remaining portion of the established duration measure. Alternatively, the control data for a second phase of the plurality of different control phases may be established so that, during the second phase, the circulated fluid may be maintained at a temperature so that, via thermal exchange at medical pad(s), the patient is maintained at the established target patient temperature for an established duration of the second phase. Again, for such purposes, the controller10may utilize a patient temperature signal82, as referenced above (e.g., to compare the corresponding patient temperature to the established target patient temperature) and to provide output signals52to the heat exchanger23and/or fluid pump21responsive thereto.

In further conjunction with the described approach, the control data for an additional phase after the first phase (e.g., a second phase or a third phase of the plurality of different control phases) may be established so that, during such phase, the circulated fluid may be warmed (e.g., at a predetermined rate) so that the patient reaches another established target patient temperature (e.g., corresponding with normothermia), and optionally, so that once such another established target patient temperature is reached, the patient is maintained at the another established target patient temperature for any remaining balance of an established duration of the additional phase or until the thermotherapy procedure is manually terminated by a user. For such purposes, the controller50may again utilize a patient temperature signal82, as referenced above (e.g., to compare the corresponding patient temperature to the another established target patient temperature), and to provide output signals52to the heat exchanger23and/or fluid pump21responsive thereto.

As noted, the controller may comprise a user interface110for receiving user input and providing user control signals, wherein the control logic of the programmable processor control module110utilizes the user control signals together with the control data to provide the output signals52. The user interface110may be further provided to establish and modify the control data stored by the programmable control module.

In some arrangements, the programmable control module may be operable to store at least two protocols comprising corresponding, different control data. In turn, the user interface110may be employable by user to select either of the two protocols for use by the programmable control module in generating the output signals.

Optionally, the user interface110may be provided to include a graphic display to visually present a plot of a target patient temperature adjustment rate that is based on the stored control data for a plurality of different temperature control phases. Further, the graphic display may be operable to display a plot of a sensed patient temperature (e.g., as sensed by the patient temperature sensor) in corresponding time relation to the plot of the target patient temperature adjustment rate. Further, the graphic display may be operable to display a plot of a sensed temperature of the circulated fluid (as sensed by the first fluid temperature sensor) in corresponding time relation to the plot of the target patient temperature adjustment rate.

In relation to one example of system1, the fluid conditioning assembly20may utilize the Arctic Sun 5000 Temperature Management System product of Medivance, Inc., located in Louisville, Colorado, USA.

FIG.8illustrates one embodiment of a method400for controlling the temperature of a patient via control of the temperature of the circulated fluid in a multi-phase temperature control system. As illustrated, the method400may include an initial step402of establishing a protocol that includes target patient temperatures for a plurality of different temperature control phases (e.g., two or more non-overlapping phases having different patient temperature exchange objectives). Such phases may be successive in time and/or spaced in time. The establishment of a protocol may be achieved via use of the programmable control module120and operatively interconnected user interface110ofFIG.3.

By way of example, the protocol may be established to include target patient temperatures for at least three phases. Such an approach facilitates a procedure in which a patient is cooled to a first target patient temperature in a first phase of therapy, maintained at or within a predetermined range of a second target patient temperature during a second phase (e.g., equal or different than the first target temperature), and warmed to a third target patient temperature during a third phase. In other embodiments, following a third phase of therapy it may be desirable to establish a fourth target patient temperature for use in temperature control during a fourth phase of therapy.

The method may further include a step404of controlling the temperature of the circulated fluid based on the protocol for each of the plurality of phases, e.g., via control of the heat exchanger23via output signals52to control the temperature of the circulated fluid ofFIGS.5-7. In that regard, the protocol may be further established at step406so as to include a set duration for one or more of the phases, e.g., via use of a programmable control module120and user interface110ofFIG.3. In turn, the controlling step404may be carried out during such phase(s) for a duration(s) that corresponds with the set duration.

In one approach, the controlling step404may be carried out in step408for each phase by controlling the temperature of the circulated fluid based upon a sensed patient temperature and the target patient temperature for such phase, e.g., via use of a patient temperature signal82from patient temperature sensor80by the programmable control module120ofFIG.1. By way of example, the patient temperature may be sensed on an ongoing basis during a given phase and compared to the corresponding target patient temperature for such phase. Based upon such comparison, system1may provide for cooling and/or heating of the circulated fluid according to any of a plurality of pre-established algorithms, e.g., via control of the heat exchanger23by the programmable multi-phase control module120of controller50ofFIG.5.

In one approach, a control algorithm may provide for simply turning on/off the cooling/heating componentry of the heat exchanger23of system1(e.g., evaporator/chiller234, chiller pump232, and mixing pump for fluid cooling, and heater229for fluid heating) in intervals that depend upon a degree of difference reflected by comparison of the sensed patient temperature and target patient temperature. In another approach, a control algorithm may provide for controlling an output magnitude of the cooling/heating componentry of the heat exchanger23of system1(e.g., evaporator/chiller234, chiller pump232, and mixing pump for fluid cooling, and heater229for fluid heating) based upon a degree of difference reflected by comparison of the measured patient temperature and target patient temperature.

In another approach, the controlling step404may be completed as step410for a given phase by controlling the temperature of a thermal exchange medium based upon a sensed patient temperature, an established target patient temperature for such phase, and an established set duration for such phase. For example, utilization of the noted parameters accommodates the determination and control use of a target patient temperature adjustment rate for the phase, wherein gradual patient cooling/warming over a desired time period may be facilitated.

In yet another approach, one or more sensed circulated fluid temperature(s) (e.g., as sensed by first temperature sensor23and optionally second temperature sensor26) may be employed together with a sensed patient temperature (e.g., as sensed by patient temperature sensor80) and established target patient temperature (e.g., comprising control data stored at programmable control module110) to control the heating/cooling of the circulated fluid. Such an approach may yield enhanced system response.

The illustrated method400may further provide for modification of a given protocol based on user input at step412, e.g., via user input at the user interface110ofFIG.7. In this regard, a modified protocol may be employed for the remaining duration of a modified phase(s) and for any phase(s) that have not yet been initiated.

In the illustrated method, a given phase may be automatically terminated at step414by expiration of a corresponding set duration included within the programmed protocol for such phase. In that regard, the termination of a given phase may generally correspond with a change in the mode (e.g., cooling or heating) or a change in the magnitude of thermal exchange between the circulated fluid and a patient.

Method400may also provide for the termination and initiation of successive phases at step416in response to a comparison of a sensed patient temperature and a target patient temperature. That is, upon determining that a target patient temperature has been reached during a given phase (e.g., via comparison of a sensed patient temperature and a target patient temperature for an initial phase of treatment), such phase may be automatically terminated and a successive phase automatically initiated. Alternatively and/or additionally, the method400may also provide for the termination and initiation of successive phases in response to the expiration of a set duration for a first one of the two successive phases. The automatic phase termination/initiation features may be selectively established by a user for a given protocol on a phase-specific basis.

The foregoing description of the present invention has been presented for purposes of illustration and description. Furthermore, the description is not intended to limit the invention to the form disclosed herein. Consequently, variations and modifications commensurate with the above teachings, and skill and knowledge of the relevant art, are within the scope of the present invention. The embodiments described hereinabove are further intended to explain known modes of practicing the invention and to enable others skilled in the art to utilize the invention in such or other embodiments and with various modifications required by the particular application(s) or use(s) of the present invention. It is intended that the appended claims be construed to include alternative embodiments to the extent permitted by the prior art.