Patent Application
20070068651
Not Applicable
Not Applicable
1. Field of Invention
This invention pertains to a heat exchange device for regulating temperature. More particularly, this invention pertains to a readily deformable heat exchange device and system applied on a person, an animal, or attached to an inanimate object.
2. Description of the Related Art
During lengthy surgical procedures, an externally applied heat exchange device is utilized to heat or cool selected portions of a patient's body during an operation lasting greater than approximately an hour in order to regulate the patient's core temperature. Heat exchange devices are also utilized for reclining patients during rehabilitation from surgery, or when bed-ridden due to a chronic illness, with heating or cooling treatment applied by one or more heat exchange devices positioned on, under, or encircling a patient's extremity to control the patient's core temperature. A typical device includes a heat exchange blanket sized to fit under a patient's torso when reclining, or a plurality of heat exchange pads wrapped in encircling relationship around selected portions of the patient's body. The prior art typically discloses a blanket or pad providing fluid transport within channels defined by a plurality of tubular channels interior of, or on an exterior surface of the device, and having one-way entry and outlet ports for attaching tubing extending to a pumping device and a fluid heating or cooling device.
Prior heat exchange pad devices typically have a pair of outer plastic and/or fabric layers sandwiched together with a serpentine tubular passageway positioned therebetween to allow passage of heating or cooling fluids in one direction from an entry port to an outlet port of the heat exchange pad. The surface of these devices are typically composed of an array of insulating, thermally inactive islands surrounded by circuitous fluid passages that exert pressure on the skin. The percentage of thermally inactive surface typically ranges between 20 to 50%. It has been observed that these devices with thermally inactive islands, when applied against a patient's body for periods of time greater than about one hour, will create uneven heating and pressure patterns on the patient's skin leading to indentations and “hot spots” in the patient's skin. To prevent uneven heating patterns on a patient's skin during extended medical procedures, or on a comatose patient, prior heat exchange pads required turning a patient relative to the heat exchange pad, and/or adjusting the position of the pad to physically change the heating patterns across the patient's skin. Additional difficulties with prior pads typically include creation of skin indentations by hard outer areas of a pad formed by pressure dilation of the interior tubing during passage of fluids therein. Additional complications with prior devices include non-planar and/or partially rigid pad surfaces formed by uneven distribution of interior tubing in the pad, resulting in outer surfaces not conforming to natural curvatures of the patient's extremity, front or back torso, and/or sides of the patient's torso.
Prior heat exchange devices have included “hot spots” near an inlet portal, and “cool zones” next to an outlet portal when heated fluids flow through the device due to the inlet flow channels being inadequately sized to rapidly disburse heating fluids within and across a full width or length of the interior, therefore leading to overheating of the body proximal to the entry port, and inadequate heating of the body along the outlet port. The prior art devices with circuitous fluid passages are prone to blockage due to misuse such as folding, crimping, or excess weight on a small area of the device. Full or partial blockage results in elevated fluid pressure in the device, compromised flow to certain parts of the device, reduced effective heat transfer area and premature device failure. To prevent blockage, it is necessary to check the device periodically, move the patient when a blockage is observed and carefully monitor the fluid pressure in the device.
An improved thermal treatment device is sought to provide for heating or cooling of animate objects or inanimate devices requiring thermal regulation. An improved thermal treatment device is sought to provide for induced hyperthermia or hypothermia for humans or animals. In addition, an improved thermal treatment device is sought to provide thermal regulation for, and pressure management against, a human or animal requiring heating or cooling without allowing overheating or underheating of the skin over extended use and without the risk of blockage, compromised flow, and elevated fluid pressure.
An improved thermal treatment device is provided for efficient heat transfer to/from a human, an animal, or an inanimate device. The thermal treatment device reduces resistance to heat transfer by providing a thin, readily pliable and conformable, and thermally active contacting surface for disposition against the object of interest. Simultaneously, pressure management is provided to reduce localized pressure on body parts such as bony prominences for extended time periods. An improved system is also provided for efficient heating or cooling to control a person's core temperature and ensuring body thermoregulation during medical treatment or extensive activities in heated or cooled environments, without producing localized pressure and/or heat induced indentations or bruising on the skin and without inducing variable temperatures across the covered skin.
According to one embodiment of the present invention, a heat exchange device for providing temperature regulation for a person's body, an animal's body, and/or an inanimate object is provided. The heat exchange device is a pliable pad with an inlet receiving a fluid at a specified temperature, a porous layer sandwiched between two non-porous layers, and an outlet for discharging the fluid after it flows through the porous layer. The porous layer is an open-cell foam through which a fluid flows.
In one embodiment, the inlet connects to an inlet manifold that distributes the fluid across an edge of the porous layer. The outlet likewise connects to an outlet manifold that collects the fluid passing out of the porous layer. The manifolds ensure the distribution of fluid across the full width of the porous layer; thereby ensuring even heat exchange across a large area of the heat exchange device.
In various embodiments, the heat exchange device is adapted for use as a pad with one or more inlets and outlets located at various positions on the pad, as a pad adapted to be wrapped around an extremity or object to be temperature regulated, as a pad adapted to be used in conjunction with a seat, and as a vest or other garment adapted to be worn.
The above-mentioned features of the invention will become more clearly understood from the following detailed description of the invention read together with the drawings in which:
An apparatus for providing temperature regulation for a person's body, an animal's body, and/or an inanimate object is disclosed. The heat exchange device is referred herein generally as 10. Those skilled in the art will recognize that, although the description contained herein may identify the use of an embodiment of the heat exchange device 10 with respect to a patient, a human, an animal, or an inanimate object, the device is not limited to be used only with the identified subject, but is suitable for use with any object, including a person, an animal, and an inanimate object. The device 10 is illustrated in various embodiments for a variety of uses, including use as a readily conformable temperature regulation pad, or heat exchange device, 10 illustrated in
The heat exchange device 10 is a generally planar, flexible pad that conforms to the shape of the object to be temperature controlled.
As seen in
Referring to
In one embodiment, the porous layer 302 is an open-cell foam, for example, a flexible cellular polyurethane or a similar synthetic hydrophilic polymer.
The porous layer 302 has a foam structure in which the cells of the foam are interconnected. The connections between the cells allow for tortuous flow of fluid 108 through the porous layer 302. In various embodiments, the porous layer 302 includes an open cell flexible polyurethane foam material with a density less than 2.0 lb/cu. ft., with less than 120 pores per inch, an elongation greater than 300%, either reticulate or non-reticulate structure, either standard or hydrophilic composition, and having a plurality of internal fluid channels extending between a matrix of interconnecting cell units. The plurality of fluid channels are randomly oriented to provide generally aligned and directed fluid flow paths across the porous layer 302 length and width between the inlet manifold 122 end and the outlet manifold 132 end. As fluid 108 enters the porous layer 302, the cells fill with fluid 108 due to both a wicking effect and a pressure differential across the cells. Upon filling the cells expand and reduce resistance to flow. In various embodiments, the porous layer 302 structure experiences inflation from 25% to 100% of its original, unfilled thickness, depending upon the internal pressure of the fluid 108. Several factors contribute to the integrity of the heat exchange portion 104, including the adhesion of the polyurethane foam of the porous layer 302 to the impervious non-porous layers 314, 316, the elongation of the foam of the porous layer 302, and the flexibility of the non-porous layers 314, 316.
The two non-porous layers 314, 316 are pliable sheets that are impervious and impermeable to the fluid 108. In various embodiments, the two non-porous layers 314, 316 are flexible polyurethane or a synthetic polymer material. In another embodiment, the outer non-porous layer 314, that is, the layer 314 that is not positioned adjacent the object to be temperature controlled, is a pliable material that has limited stretch and the inner non-porous layer 316, that is, the layer 316 that is positioned adjacent the object to be temperature controlled, is a pliable material that is stretchable or elastic. In this embodiment, the inner non-porous layer 316 is forced against the object to be temperature 25 controlled by the expansion of the porous layer 302 by the fluid 108 flowing through the layer 302 because the outer non-porous layer 314 does not expand to accommodate the expansion of the porous layer 302.
In one embodiment, the porous layer 302 has an initial thickness of between about 0.08 inches and about 0.24 inches when fluid 108 is not flowing and the porous layer 302 is not pressurized by the application of a fluid 202 to the inlet 102. When a pressure differential is applied across the inlet 102 and the outlet 106, the fluid 202 flows from the inlet 102, through the manifold 122, and into the porous layer 302.
In one embodiment, a water flow rate of 0.25 to 0.50 gallons per minute results in a typical range of internal pressure maintained by the porous layer 302 of between two and five pounds per square inch. The pressure of the fluid 108 in the porous layer 302 causes the porous layer 302 to expand in thickness. In various embodiments, the thickness of the porous layer 302 increases by 0.02 to 0.24 inches. This increase in thickness causes a displacement of the non-porous layers 314, 316 normal to the plane of the porous layer 302. In the embodiment in which the heat exchange device 10 is wrapped around or secured to a patient, for example, the encircling device 10-C illustrated in
Referring to
The inlet manifold 122 and the outlet manifold 132 are formed of two manifold sheets 304, 306 of a pliable non-porous material that is impermeable to the fluid 202, 204, 108, 206, 208. In the illustrated embodiment, the manifold sheets 304, 306 are large sheets that extend past the edge of the heat exchange portion 104 and have their central portion cut out. The manifold sheets 304, 306 are sealed near the perimeter of the non-porous sheets, or layers, 314, 316 of the heat exchange portion 104. In other embodiments, the manifold sheets 304, 306 are each sheets without their central portion cutout, and the manifold sheets 304, 306 are bonded to the surface of the non-porous sheets, or layers, 314, 316 of the heat exchange portion 104 or the portion of the sheets 304, 306 adjacent the perimeter of the heat exchange portion 104 are attached to the heat exchange portion 104 at the seal connection 142. In various embodiments, the manifold sheets 304, 306 are bonded to the heat exchange portion 104 by heat, radio frequency, impulse or induction sealing, or welding, or chemical or adhesive bonding. Illustrated in
The two manifold sheets 304, 306 each have a perimeter that is joined to form an outside seam 210. The outside seam 210 forms a seal that is breached for the inlet 102 and the outlet 106, otherwise, the outside seam 210 seals the fluid 202, 204, 108, 206, 208 within the heat exchange pad 10. In various embodiments, the manifold sheets 304, 306 are bonded together by heat, radio frequency, impulse or induction sealing, or welding, or chemical or adhesive bonding along an outer perimeter 210 to form an outer circumferential seal that prevents fluid leakage from the perimeter portions of the heat exchange pad 10.
In the illustrated embodiment of
Referring to
The flow diverters 124 in the manifolds 122, 132 provide very little flow restriction between the inlet 102 and the heat exchange portion 104 and between the heat exchange portion 104 and the outlet 106. The major flow restriction is at the junction of the inside flow channel 336 and the first end 322 of the porous layer 302. For the inlet manifold 122, this flow restriction causes the fluid 204 to spread across and through the manifold 122 instead of immediately entering the porous layer 302 in the vicinity of the inlet 102. Since flow resistance in the porous layer 302 is much greater than the flow resistance in the manifolds 122, 132, the fluid 204 fills the inlet manifold 122 first and then travels along a direct path through the porous layer 302. Thus, the fluid 204 enters the porous layer 302 across its full width and the fluid 108 leaves the porous layer 302 across the full width. In this manner, the full effect of the temperature controlled fluid 108 is felt across whole surface area of the heat exchange portion 104.
In the illustrated embodiment, the porous layer 302 has a non-porous skin 314, 316 and the manifold sheets 304, 306 have their central portion cut out with the perimeter of the cutout portion having a seal connection 142 with the porous sheet 302 near the perimeter of the porous sheet 302. The seal connection 142 ensures that the fluid 204, 108, 206 does not escape the confines of the heat exchange device 10-A. Additionally, the manifold sheets 304, 306 have a seal 402 that joins the manifold sheets 304, 306 near the inlet 102 and the outlet 106 and prevents the inlet fluid 204 from passing directly into the porous layer 302 adjacent the inlet 102 and the outlet fluid 206 from passing directly from the porous layer 302 adjacent the outlet 106. That is, the fluid 202 enters the inlet 102, flows within the inlet manifold 122, turns in the direction of fluid 204, and fills the manifold 122. The outside seam 210, the seal connection 142, and seal 402 form a fluid seal that keeps the fluid 204 within the manifold 122. Seal 402 prohibits fluid flow into the porous layer 302 near the inlet 102 and outlet 106, while the seal connection 142 allows fluid flow into layer 302. Thus the fluid 204 is prevented from entering the porous layer 302 at the ends and must enter the porous layer 302 at the side 322 and the fluid 206 can only leave at the opposite side 324 of the porous layer 302.
Connected to the inlet port 112 is a length of flexible supply tubing 602 and connected to the outlet port 116 is a length of a flexible exhaust tubing 606. The tubing 602, 606 connects the heat exchange device 10-C to a pump unit 612. The pump unit 612, in one embodiment, includes a fluid pump that moves the fluid 202, 108, 208 through the heat exchange device 10-C. The fluid pump develops sufficient pressure at the required flow rates. In another embodiment, the pump unit 612 includes a temperature conditioning device that conditions the fluid in the pump unit 612 such that the fluid discharging from the outlet of the pump unit 612 and entering the supply tubing 602 is at a specified temperature. Although illustrated with the heat exchange device 10-C of
In another embodiment, a source of temperature controlled pressurized fluid 202 is provided to the supply tubing 602 and the fluid 208 discharged from the heat exchange device 10 is discarded after flowing from the exhaust tubing 606. In this embodiment, the pump unit 612 is not used. In still another embodiment, the pump unit 612 provides temperature controlled fluid 202 to the heat exchange device 10 and the exhaust fluid 208 is not recirculated by the pump unit 612, but is discarded.
In one embodiment, the heat exchange device 10-C is wrapped around the forearm 610 of a human after the pump unit 612 supplies pressurized fluid to the heat exchange device 10-C. In this embodiment, the heat exchange device 10-C applies only as much compression to the body portion 610 as desired by the person applying the heat exchange device 10-C. In another embodiment, the heat exchange device 10-C is wrapped around the forearm 610 of a human before the pump unit 612 supplies pressurized fluid to the heat exchange device 10-C. In this embodiment, the heat exchange device 10-C applies a compressive force to the body portion 610 when the pump unit 612 supplies pressurized fluid to the heat exchange device 10-C.
In still another embodiment, the heat exchange device 10-C is wrapped around the forearm 610 of a human before the pump unit 612, which includes a temperature conditioning device, supplies pressurized and temperature controlled fluid to the heat exchange device 10-C. The pump unit 612 provides pulsating pressurized fluid to the heat exchange device 10-C. In this embodiment, the heat exchange device 10-C applies heat or cold together with a compressive force to the body portion 610 when the pump unit 612 supplies a pulse of pressurized, temperature controlled fluid to the heat exchange device 10-C and that compressive force is removed after the pulse terminates. The heat exchange device 10-C applies an intermittent compressive force to the body portion 610 that is synchronized with the pressure pulses generated by the pump unit 612. When pressure is applied to the heat exchange device 10-C by a pulse from the pump unit 612, the thickness 622 of the heat exchange portion 104 increases, thereby squeezing the body portion 610 and improving thermal contact between the heat change device 10-C and the body portion 610. For the time between the pressure pulses from the pump unit 612, the thickness 622 decreases, thereby releasing the compressive force on the body portion 610 and reducing thermal contact. By controlling the rate of increase of the pressure, the duration of the pressure pulse, the rate of decrease of the pressure, and the duration between pulses, and by controlling the temperature of the fluid simultaneously, the intermittent compression of the body portion 610 can be used to provide therapeutic value to a patient. The intermittent compression results in the gentle application of force against a patient's skin and can prevent static pressure-induced skin sores and/or can massage an extremity for inducing return blood flow through the body portion 610. In one embodiment, the intermittent compression results in a gradual compression, or progressive wave, moving from the inlet manifold 122 to the outlet manifold 132.
In one embodiment, the outer non-porous layer 314 is a pliable material that has limited stretch and the inner non-porous layer 316 is both pliable and stretchable, or elastic. In this embodiment, after the heat exchange device 10-C is wrapped around the body portion 610, fluid 202 is applied to the device 10-C and the porous layer 302 expands in thickness 622. Because the outer non-porous layer 314 is not stretchable and the inner non-porous layer 316 is stretchable, the inside of the device 10-C, which is bounded by the inner non-porous layer 316, moves inward, applying pressure to the wrapped body portion 610 due to the decreasing inside diameter of the wrapped device 10-C.
In one embodiment, the inlet manifold 122 is located at a distal end of the body portion 610, thereby causing the pressure pulse to propagate through the heat exchange portion 104 as a progressive wave. This progressive wave moving toward the proximal end assists in moving the blood toward the heart.
In the illustrated embodiment, straps, or attachments, 704 are shown for securing the heat exchange device 10-D to the seat 702. In another embodiment, the heat exchange portion 104 is self-supporting because of the expansion of the porous layer 302 due to the application of pressurized fluid 108.
In this embodiment, the heat exchange device 10-D does not require supporting attachment to the seat 702.
In the illustrated embodiment, the manifolds 122, 132 are located at the edges of the vest 10-E with the inlet port 112 and the outlet port 116 located at the bottom of the vest 10-E. Those skilled in the art will recognize that the ports 102, 106 can be located at other positions on the heat exchange device 10-E without departing from the spirit and scope of the present invention.
The inlet section 902, the first manifold channel 904, and the second manifold channel 906 are equivalent to the inlet manifold 122 illustrated in FIGS. 1 to 8. Likewise, the outlet manifold channel 914 and the outlet section 912 are equivalent to the outlet manifold 132 illustrated in FIGS. 1 to 8. The various channels 904, 906, 914 and sections 902, 912 include a pattern of flow diverters 124 formed in the channels 904, 906, 914 and sections 902, 912. The flow diverters 124 help to evenly distribute the fluid 202 as it flows through the second manifold channel 906 into the side 322 of the heat exchange portion 104.
The first and second manifold channels 904, 906 form a folded channel such that the second manifold channel 906 is oriented in the opposite direction as the outlet manifold channel 914 aids in the even distribution of fluid 108 flowing through the heat exchange portion 104. The fluid 202 enters the second manifold channel 906 at a second manifold channel entry end 906-A and the fluid flows along the length of the second manifold channel 906 to a second manifold channel distal end 906-B. As the fluid 202 flows along the length of the second manifold channel 906 it also enters the side 322 of the heat exchange portion 104. On the opposite side 324 of the heat exchange portion 104 the fluid 108 flows into the outlet manifold channel 914 along its length. The fluid 206 flows in the outlet manifold channel 914 from the distal end 914-B to the outlet manifold channel exit end 914-A. The position of the outlet manifold channel exit end 914-A at the furthest point from the second manifold channel entry end 906-A ensures that the fluid 108 is evenly distributed across the full width and length of the heat exchange portion 104. The opposing orientation of the second manifold channel 906 relative to the outlet manifold channel 914 is useful for larger configurations of the heat exchange device 10-F in which the heat exchange portion 104 has a length along the second manifold channel 906 that is greater than the width between the second manifold channel 906 and the outlet manifold channel 914.
The inlet port 112 and the outlet port 116 are lengths of tubing positioned between the two non-porous layers 1004 such that each one has its inboard end in communication with one of the sections 902, 912. In one embodiment, the inlet and outlet ports 112, 116 terminate at their outboard ends in connectors that allow the ports 112, 116 to be connected to other lengths of tubing 602, 606.
The embodiment illustrated in
In operation, when fluid 202 is pumped into the inlet port 112 of the heat exchange device 10-F, the inlet section 902, the first manifold channel 904, and the second manifold channel 906 fill with the fluid 202 and form channels 332, 334, 336 as illustrated in
By alternating the pumping of fluid 202 into the heat exchange device 10-F, the heat exchange portion 104 will alternate expanding and reducing in thickness. When the heat exchange device 10-F is used with a patient 502, such alternations of thickness has a beneficial effect on the patient 502. For example, a patient 502 lying on a heat exchange device 10-F for an extended period of time will experience undue pressure on portions of their body, such as the pelvis, where a bony protuberance compresses soft tissue between the protuberance and the device 10-F. By controlling the rate of increase of the pressure, the duration of the pressure pulse, the rate of decrease of the pressure, and the duration between pressure pulses, and by controlling the temperature of the fluid 202 simultaneously, the intermittent changes in the thickness of the heat exchange portion 104 can be used to relieve the compression and/or pressure experienced by the patient 502 and provide therapeutic value.
The heat exchange device 10 includes various functions. The function of distributing flow in the manifolds 122, 132 is implemented, in one embodiment, by the flow diverters 124 formed by connecting the first manifold sheet 304 to the second manifold sheet 306 at selected spots in the manifolds 122, 132. In another embodiment, the function of distributing flow in the manifolds 122, 132 is implemented by the inlet section 902, the first manifold channel 904, and the second manifold channel 906 providing fluid 202 to the heat exchange portion 104 and the outlet manifold channel 914 and the outlet section 912 receiving fluid 108 flowing from the heat exchange portion 104.
The function of containing a porous layer 302 is implemented, in one embodiment, by the two non-porous sheets 314, 316 encasing the porous layer 302. In one embodiment, the two non-porous sheets 314, 316 are fixed to the two surfaces of the porous layer 302, such as with an adhesive or other method. In another embodiment, the porous layer 302 has a non-porous skin that is impermeable to the fluid 108, thereby preventing the fluid 108 from escaping the sides of the porous layer 302. In another embodiment, the function of containing a porous layer 302 is implemented by the two non-porous layers, or sheets, 1004 that encapsulate the porous layer 302.
The function of distributing the fluid 202 to the porous sheet 302 is implemented, in one embodiment, by the inlet manifold 122. In one embodiment, the inlet manifold 122 provides fluid communication between the inlet 102 and the porous sheet 302. In one embodiment, the inlet manifold 122 includes flow diverters 124 that ensure the distribution of the inlet fluid 204 across the end of the porous sheet 302. In another embodiment, the function of distributing the fluid 202 to the porous sheet 302 is implemented by the inlet section 902, the first manifold channel 904, and the second manifold channel 906 providing fluid 202 to the heat exchange portion 104.
The function of receiving the fluid 206 from the porous layer 302 is implemented, in one embodiment, by the outlet manifold 132. In one embodiment, the outlet manifold 132 provides fluid communication between the porous layer 302 and the outlet 106. In one embodiment, the outlet manifold 132 includes flow diverters 124 that ensure the even collection of the fluid 206 across the end of the porous layer 302. In another embodiment, the function of receiving the fluid 206 from the porous layer 302 is implemented by the outlet manifold channel 914 receiving fluid 108 flowing from the heat exchange portion 104.
From the foregoing description, it will be recognized by those skilled in the art that a heat exchange device 10 has been provided. The heat exchange device 10 includes an inlet 102 receiving a temperature controlled fluid 202 that is distributed to and passes through a porous layer 302 before being collected and discharged through an outlet 106. In one embodiment, the porous layer 302 is encapsulated in a pair of non-porous layers 314, 316. In one embodiment, a pair of non-porous layers 304, 306 form a pair of manifolds 122, 132 for distributing the inlet and outlet fluid 202, 208 to and from the porous layer 302. In another embodiment, the porous layer 302 is encapsulated between two non-porous layers 1004 and the non-porous layers 1004 form various channels 904, 906, 914 and sections 902, 912 that allow the incoming fluid 202 to flow within the heat exchange device 10. In one embodiment, the manifolds 122, 132 and/or the channels 906, 914 include flow diverters 124 for distributing the fluid 204, 206 to and from the porous layer 302.
While the present invention has been illustrated by description of several embodiments and while the illustrative embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicant's general inventive concept.
