Patent Publication Number: US-2022218917-A1

Title: Metalized fabric heating device for medical soulutions

Description:
REFERENCE TO RELATED APPLICATION 
     This Application is a continuation-in-part of U.S. patent application Ser. No. 16/269,430 filed Feb. 6, 2019 and entitled “Metalized Fabric Heating Device For Medical Solutions”, which claims the benefit of U.S. Provisional Patent Application Ser. No. 62/471,103 filed Mar. 14, 2017 and entitled “Metalized Fabric Heating Blanket”, which is also a continuation-in-part of U.S. patent application Ser. No. 15/920,383 filed Mar. 13, 2018 and entitled “Metalized FabricHeating Blanket And Method Of Manufacturing Such”, which is a continuation-in-part of U.S. patent application Ser. No. 15/841,044 filed Dec. 13, 2017 and entitled “Metalized Fabric Heating Blanket”. 
    
    
     TECHNICAL FIELD 
     This invention relates generally to heating devices, and more particularly to heating devices utilized to warm medical solutions contained within intravenous lines, intravenous bags, anesthesia and respiratory circuits, airway tubes, and the like. 
     BACKGROUND OF THE INVENTION 
     Intravenous solutions, medications in liquid fluids, blood, plasma, and other form, collectively referenced hereinafter as solutions, are typically administered to the patient to provide select fluids or medications directly into the patient&#39;s veins. These solutions are kept in IV bags to which an IV tube or line is coupled. The opposite end of the IV tube is fitted with an IV needle or catheter which punctures the patient&#39;s skin and enters the patient&#39;s vein. 
     A common problem with such IV solutions and blood is that they are usually stored at room temperature or refrigerated. As such, their temperatures are far below the normal body temperature of a patient. The infusion of these cool solutions into a patient may cause discomfort, or may even lower the body temperature of the patient to the point of causing hypothermia, which has been associated with increased infection rates, cardiac instability, coagulation complications and increased overall cost to the healthcare facility. 
     In order to avoid this problem, medical facilities may warm the solutions prior to administering to the patient. The solution may be warmed by placing them into a warming cabinet which raises the temperature of the solution. However, the rate of the administration can allow the solutions to cool down in the IV line. 
     Other devices have been designed to warm the solution. One such device is a pair of warming plates between which the IV tube is positioned in a serpentine pattern to increase the contact area between the warming plates and the IV tube. A problem with this type of device is that the warming plate may cause hot spot in the IV tube causing the IV line to overheat the solutions, posing a risk to the patient. 
     Another device is in the form of a triple lumen tube wherein the IV line is surrounded by a circulating water jacket. Heat is exchanged between the warm water extending to the IV tube lumen in order to warm the IV solution passing through the IV tube. This type of device requires the circulation of heated water, which may cause entanglement of the lines or a spillage of the warming water. The warming line requires a circulating water bath which may present a risk of infectious material build up in the water itself if not maintained properly. 
     A similar problem also exists with respiratory or anesthesia circuits or airway tubes which provide air or gases to the patient. A breathing tube in a cool environment may create condensation within the tube or circuit during the breathing process, this may be referred to as “rain out”. This condensation may interfere with the proper administration of air or gases to the patient, and thus should be avoided. For ease of explanation, these gases for medical purposes are also referenced herein as “solutions” or “fluids”. 
     It would be beneficial to provide a device for warming IV solutions or respiratory gases to a patient which provides a safer and more consistent heat than those of the prior art. Accordingly, it is to the provision of such that the present invention is primarily directed. 
     SUMMARY OF THE INVENTION 
     In a preferred form of the invention a heating device for warming medical solutions contained within a medical device, comprises an elongated first electrically insulative tube defining a medical solution tube channel, an elongated electrically resistive heating element tube mounted concentrically about the first electrically insulative tube, an elongated second electrically insulative tube mounted concentrically about the electrically resistive heating element tube, an elongated flexible metallic foil tube mounted concentrically about the second electrically insulative tube, and an elongated thermoplastic tube mounted concentrically about the flexible metallic foil tube. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a warming blanket embodying principles of the invention in a preferred form. 
         FIG. 2  is a cross-sectional view of a portion of the warming blanket of  FIG. 1 . 
         FIG. 3  is a top view of a portion of the warming blanket of  FIG. 1 . 
         FIG. 4  is a plan view of the warming blanket of  FIG. 1 . 
         FIG. 5  is a plan view of a warming blanket embodying principles of the invention in another preferred form. 
         FIG. 6  is a cross-sectional view of a portion of the warming blanket of  FIG. 5 . 
         FIGS. 7-12  are a series of top view of a warming blanket in another preferred embodiment, showing the manufacturing process. 
         FIG. 13  is a cross-sectional view of a portion of the warming blanket shown in  FIGS. 7-12 . 
         FIG. 14  is a perspective view of the heating device embodying principles of the invention in another preferred form. 
         FIG. 15  is a perspective view of the heating device embodying principles of the invention in another preferred form. 
         FIG. 16  is a perspective view of the heating device embodying principles of the invention in another preferred form. 
         FIG. 17  is a cross-sectional view of the heating device of  FIG. 14 . 
     
    
    
     DETAILED DESCRIPTION 
     With reference next to the drawings, there is shown a warming blanket  8  made in part with a metalized fabric  10  embodying principles of the invention in a preferred form. The warming blanket  8  has a lower surface  11  which is intended to face away from a person (patient) overlaid with or donning the material and an upper surface  12  which is intended to face the person (patient). The metalized fabric includes a first layer  15  of clear thermoplastic (for example a polyethylene) material, a second layer  16  of vaporized aluminum material (solid metalized layer), a third layer  17  of thermoplastic (for example a polyethylene) material, and a fourth layer  18  of lofted billow spunbond thermoplastic (for example a polypropylene) non-woven material. The exterior surface of the first layer  15  constitutes the fabric lower surface  11 , while the exterior surface of the fourth layer  18  constitutes the upper surface  12 . 
     The warming blanket  8  also includes a resistive heating portion  30  positioned between the third layer  17  and the fourth layer  18 . The resistive heating portion  30  is positioned distally from the perimeter or outer edge of the warming blanket  31  and metalized fabric  10  so that a surrounding margin  32  is formed therebetween. 
     The resistive heating portion  30  has heater trace resistors or heating elements  34  arranged in a longitudinal array with each heating element  34  extending laterally, as best shown in  FIG. 4 . The heating elements  34  are formed by depositing a conventional electrically conductive ink upon the third layer  17  in the desired pattern. The heating elements  34  are electrically joined together through a pair of conductive tapes  35  coupled to the ends of the heating elements. The conductive tapes  35  may be made of a metal, such as copper, or in the alternative, the conductive tapes  35  may be replaced by additional conductive ink strips or any other configuration of a conductive element. The resistive heating portion  30  may also include a convention flat flex crimp pin type connectivity or coupler  36  to allow a quick connect to a controller  43 , which may also include thermistors  37 , or thermocouples, to regulate the current and temperature of the warming blanket  8 . 
     The warming blanket  8  may have an input voltage of 100 to 250 VAC and a maximum blanket power of 7 W @12 VDC to 109 W@ 48 VDC. 
     The metalized fabric is manufactured by joining the third layer  17  of thermoplastic material having the resistive heating portion  30  thereon to the fourth layer  18  of spunbond thermoplastic non-woven material. The second layer  16  of vaporized aluminum material is then deposited or joined onto the third layer  17  via a vacuum deposit chamber. The first layer  15  is then extruded or joined onto the second layer  16 . The combination of layers is then passed through cold calender rollers which seals the layers together in a pattern that forms a series, matrix or field of large pillowed areas or regions  20  surrounded at four sides by smaller pillowed regions  21 . The large pillowed region  20  is generally oval in shape with a longitudinal length LA of approximately 3/16 of an inch and a lateral width LW of approximately 2/16 of an inch. The seals  23  themselves are non-continuous or fragmented, as they are formed by several unjoined segments  24  which also helps in providing a less stiff feel to the metalized fabric by breaking up the seals which tend to be stiffer than those areas of the fabric which are not sealed, i.e., the bonding of the material at the seals tends to stiffen the sealed areas and thereby tends to stiffen the overall material decreasing its drapability and loft. The metalized fabric of the present invention is fused, bonded or sealed on approximately 14% of the material, as opposed to the prior art material which included at a minimum 18% fusing, bonding or sealing. 
     It is believed that the position of the heating elements between the person and the metalized second layer  16  provides for a more even distribution of heat. Heat produced from the heating elements is reflected by the metalized second layer  16  back onto the person. Thus, heat initially drawn away from the person is not lost to ambient environment and is instead used to heat the person, a distinct advantage over the prior art. 
     It is believed that the pillowing of the metalized fabric provides for greater insulative qualities, a softer feel, better glare reduction, improved drapability, and improved loft. 
     Another discovered advantage has been the materials improved cross-direction tearing resistance. A test was conducted comparing the prior Thermoflect metalized material, previously described, to the metalized fabric of the present invention. The metalized fabric of the present invention was found to have a cross directional tearing factor of 435.7, while the prior Thermoflect metalized material had a tested cross directional tearing factor of 393. This test shows an improvement in tearing resistance of approximately eleven percent (11%). 
     As an alternative to the first embodiment, a second embodiment of the invention in a preferred form is shown in  FIGS. 5 and 6 . Here, warming blanket  40  has the previously described first layer  15 , second layer  16 , third layer  17  and fourth layer  18  are formed as a unitary structure. A fifth layer  41  is coupled to the fourth layer  18 . The fifth layer  41  may be a spunbond thermoplastic (for example a polypropylene) non-woven material. The fifth layer  41  includes the resistive heating portion  30 , and especially all the previously described components including the heating elements  34  which may be in the form of electrically conductive ink, bonded or coupled to the interior surface  42  of the fifth layer  41  facing the fourth layer  18 . 
     A pair of double-sided tape strips  44  may be applied to the fifth layer  41  so that it may be attached or coupled to a pre-existing warming blanket. Also, if need be, the fifth layer  41  with the electronic components may be easily removed or released from the warming blanket. As such, an existing warming blanket may be converted from a static or strictly body heat capturing warming blanket to a positive or active electrically resistive heat added warming blanket. The warming blanket may then be reconfigured to a static body heat capturing warming blanket by removing the fifth layer  42  and electronic components. In this manner, the electronic components may be attached and then removed from multiple warming blankets should they become soiled or otherwise unusable and may be disposed. This disposability decreases the expense involved in providing warming blankets having resistive heating capabilities. 
     It is believed that this embodiment provides an even higher amount of heat dispersement or distribution as a portion of the heat from the heating elements  34  initially radiating in the direction away from the patient is dispersed as it passes through the fourth layer  18 , is reflected by the second layer  16 , and then disperses even more as it passes again through the fourth layer  18  prior to reaching the person, i.e., the heat passes through the fourth layer  18  twice before reaching the person. This also allows the temperature of the conductive heating element  34  to be set at a lower temperature because of the additional reflected heat being directed back to the person. 
     It should be understood that as used herein the term “lofted” is intended to mean something that is fluffed, fluffy, expanded, expanded layers, or the like. Also, the term “billow” or “billowed” is intended to mean raised, embossed, undulating surface, having lofted areas, or the like. The use of a lofted inner material is believed to allow the heat from the heating elements  34  and that reflected back from the metalized second layer  16  to spread or diffuse the heat so as to provide a more even heating, as opposed to a concentration of the heat should a thin layer be utilized. 
     With reference next to the embodiment of  FIGS. 7-13 , there is shown a heating blanket  40  in another preferred form of the invention. 
     Here, the heating elements  34  are formed by adhering a small patch  53  of electrically insulative spunbond material to an exterior facing surface of a carbon veil material  52 , wherein the carbon veil material  52  may be a sheet or mat of randomly orientated carbon fibers. The carbon veil material  52  is then adhered, through sewing, adhesive, sonic welding or the like, to a second layer of electrically insulative spunbond material  63  which will be later bonded to a previously discussed metalized fabric  54 . The metalized fabric  54  is generally the same as that previously described and which includes the first layer  15  of clear thermoplastic (for example a polyethylene) material, the second layer  16  of vaporized aluminum material (metalized layer), a third layer  17  of thermoplastic (for example a polyethylene) material, and a fourth layer  18  of lofted billow spunbond thermoplastic (for example a polypropylene) non-woven material. The third layer  17  and fourth layer  18  may also be electrically insulative. 
     Next, a conductive strip in the form of a conductive ink layer  56 , which may be made of nickel or silver ink, is deposited, sprayed upon, or printed onto opposite side edges of the carbon veil material  52  as thin strips or side rails  56 , also shown in  FIG. 7 . The conductive ink side rails  56  acts to locally connect the random conductive fibers at different depth of the carbon veil material  52 . 
     With reference next to  FIG. 8 , lower conductive strips  58  are then sewed on, or alternatively attached by electrically conductive adhesive or other bonding method, onto a bottom edge of the carbon veil material  52 . Each lower conductive strip  58  is electrically coupled to a side rail  56 . The lower conductive strips  58  may be made of an aluminum foil or other electrically conductive material. The lower conductive strips  58  are electrically insulated from the carbon veil material  52 . The lower conductive strips  58  have connecting ends  60  which are spaced from each other so as to accept a connection circuit board described in more detail hereinafter. 
     With reference next to  FIG. 9 , side conductive strips  62  are then sewed onto the conductive ink side rails  56  in electrical contact with the conductive ink side rails  56 . The nickel boundary of the conductive ink side rails  56  prevent resistance drift from occurring. The side conductive strips  62  are also sewn so as to be in electrical contact with the lower conductive strips  58 . 
     The second layer of spunbond material  63  is then laminated or otherwise bonded (adhesive, sonic welding, or the like) about the periphery of the fourth layer (spunbond material)  18  and/or carbon veil material  52 , thereby sandwiching the carbon veil material  52  between two layers of spunbond material. The second layer of spunbond material  63  protects the carbon veil material  52  while providing a soft exterior layer for patient comfort and safety. The combination of the second layer of spunbond material  63  with the first layer of spunbond material (metalized fabric) essentially creates an envelope surrounding or encasing the carbon veil. 
     With reference next to  FIG. 10 , a hole or opening  66  is cut into the metalized fabric  54  so as to expose the connecting ends  60  of the lower conductive strips  58 . A backing plate  68  is then attached to the backside of the second layer of spunbond material  63  at the position of the opening  66 , as shown in  FIG. 11 , or to a patch of spunbond material which is then adhered to the patient side of the blanket. The backing plate  68  may be passed through a slot or cut  67  in the second layer of spunbond material  63  so as to be placed flush against the patch  53 , as shown in  FIG. 13 . The use of the backing plate  68  provides local support of the connection points of the warming blanket as well as providing pressure between the contact surfaces of the thermistor board and the lower conductive strips  58  (cross rails). The backing plate  68  includes a set of mounting prongs  69  which extend through or are punched through the patent  53  and carbon veil material  52  so that they may engage, fit upon a snap-on circuit board  70  containing thermistors (thermistor plate  71 ), or thermocouples. The circuit board  70  is then mounted to the exterior surface of the metalized fabric  54  and connected to the connecting ends  60  of the lower conductive strips  58 , as shown in  FIGS. 12 and 13 . The circuit board  70  includes a large array of vias to assist heat transfer to the where the thermistors are located. The use of a large circuit board for connection purposes provides a more accurate average temperature of the heating fabric (carbon veil material), i.e., the temperature is sensed over a larger area for averaging purposes to minimize the possibility of errors. The vias transfer heat to the top side of the circuit board so that the thermistors can be captured within the connector housing. This also shields the thermistors for the safety of the operator. 
     In use, electric current is controlled through the circuit board  70  and passed to the connecting ends  60  of the lower conductive strips  58 . The current then travels to the side conductive strips  62  and conductive ink side rails  56  where it is then passed to the carbon veil material  52  wherein resistive heat is created. The metalized fabric reflects the heat to produce an even distribution and more efficient use of the heat. The lofted material layers diffuse the heat to avoid a concentration of heat or hot spot. 
     The circuit board  70  uses multiple thermistors to minimize variance. The placement of the thermistors on the circuit board  70  enables them to be on a re-useable portion of the warming blanket  50  rather than the disposable “blanket” or material covering portion. This placement reduces the replacement costs of the warming blanket. 
     It is believed that the sewing of the conductive foil of the lower conductive strips  58  and side conductive strips  62  to the second layer of spunbond material  63  and carbon veil material  52  provides a better electrical connection. It is also believed that the sewing maintains a better drape ability of the warming blanket. The improved drape ability is important for patient comfort, effective warming, and reduced cost of manufacture. 
     The sewing process of the lower conductive strips  58  and the side conductive strips  62  preferably is accomplished with the use of non-conductive cotton-poly blend threads. 
     It should be understood that the description is for one method of constructing the warming blanket. The exact sequence of the steps involved in the construction may differ while still embodying the invention. 
     It should be understood that sewing, adhesive bonding, sonic welding, heat welding, or any other conventional method of bonding or coupling, as used herein, are equivalent. 
     With reference next to  FIG. 14 , there is shown a warming device or heating device  80  which is adapted to be used to warm medical solutions contained within an intravenous tube or IV line IVL. As the warming device or heating device  80  is utilized in conjunction with other medical devices (IV line) containing a solution, it is referenced hereinafter as a heating device  80  for medical solutions. 
     The heating device  80  uses the same construction method described in the previous embodiments. As such, the heating device includes the previously described metalized fabric  54  having an elongated, tubular form of the metalized or metallic layer  16  and spunbond material  18  or  63 . Specifically, the metalized fabric  54  includes an elongated tube of the first layer  15  of clear thermoplastic (for example a polyethylene) material, an elongated tube of the second layer of vaporized aluminum material (metalized layer), an elongated tube of the third layer  17  of thermoplastic (for example a polyethylene) material, and an elongated tube of the fourth layer  18  or  52  of lofted billow spunbond thermoplastic (for example a polypropylene) non-woven material. An elongated tube of the electrically resistive heating element in the form of the previously described carbon veil  52  is positioned concentrically between the third layer  17  and the fourth layer  18 / 63 . The third layer may also be electrically insulative. Here, the heating device  80  is in the form of a generally tubular sleeve wherein each previously described layer is mounted concentrically to the inboard surface of the previous layer so as to form a sleeve with concentric layers, the term “inboard” meaning the inside or interior surface of the tubular form, rather than the outboard, exterior, or outside surface of the tubular form. 
     It should be understood that while this is a preferred orientation, the warming device layers may be oriented in reverse order with the first layer  15  as the innermost layer. However, this is not preferred as it is believed that by orienting the metallic layer  16  as the outermost layer with respect to the carbon veil  52  the heat produced by the carbonveil is reflected back towards the IV line IVL to provide a consistent and efficient heating of the IV solution. 
     The heating device metalized fabric  54  is formed as an elongated flexible material tube or sleeve  82  having an interior IV line or central channel  84  therein extending from a first end  86  to a second end  88 . The first end  86  is positioned closely adjacent the connection between an IV solution bag IVB and the IV line IVL. The second end  88  is positioned adjacent the terminal end or coupler end to the IV needle IVN of the IV line IVL. 
     The flexible material tube  82  has the vaporized aluminum material (solid metalized layer, or second layer  16 ) of the metalized fabric  54  facing outwardly and the spunbond material  63  facing inwardly towards the IV line IVL. The metalized fabric  54  is coupled to an electrical controller  43  through an electrical coupler  36  as previously described. The controller  43  may adjust the current passed to the carbon veil  52  to regulate or control the temperature produced by the heating device  80 . 
     In use, the IV line IVL is passed through the heating device channel  84  so that the heating device  80  covers at least a majority of the IV line IVL. 
     With the heating device  80  activated, the heat produced by the current controlled by controller  43  and passing through the carbon veil  52  is directed towards the heating device channel  84  and the IV line IVL therein. This heat warms the solution contained within the IV line IVL prior to the solution entering the patient through the IV needle or catheter IVN coupled to the IV line IVL. The heat produced by the carbon veil  52  is also reflected by the vaporized aluminum material (second layer  16 ) back towards the carbon veil  52  so that more of the heat is directed to the IV line IVL positioned within the central channel  84 . This reflected heat also produces a greater efficiency and a more even distribution of the heat, which avoids the creation of hot spots or the like. 
     The quantity of heat produced by the heating device  80 , or its temperature, is regulated through the previously described controller  43  and coupler  36 . The quantity of heat may be tied to or regulated according to the flow rate of the solution through the IV line IVL, i.e., the faster the fluid flows through the IV line the higher the temperature of the heating device  80  should be set to compensate for the shorter time the fluid passes through the heating device  80 . This correlation between the flow rate of the solution and the flow of current from the controller  43  may be an automated program wherein the controller is in communication with the flow rate mechanism or controller of the IV solution, or may be manually controlled through a manual activation or desired temperature adjustment of the controller  43 . 
     It should be understood that the tubular sleeve of the heating device may be formed with fasteners on opposite ends of a sheet type form of the device which may be fastened together to form a tube, or otherwise fastened together or positioned to form a tube. This will enable the device to be wrapped about or mounted to the IV line IVL and then fasten the ends together or overlapping fashion even after the needle IVN is inserted into a patient, i.e., it does not require that the IV tube be threaded through a tubular structure or central channel  84  prior to the IV needle IVN being inserted into the patient. 
     With reference next to  FIG. 15 , it should be understood that a heating device  100  of the present invention in another form may be configured, as previously described, to surround, or at least partially surround, the IV bag IVB, alone or in addition to surrounding the IV line IVL. 
     With reference next to  FIG. 16 , a heating device  110  in another form may be configured to surround a respiratory tube or circuit RC, rather than an IV line, as shown in  FIG. 16 . By surrounding the respiratory tube, the gases within the respiratory tube are warmed to prevent condensation within the respiratory tube. As such, it should be understood that the present heating device may be utilized with many different types of medical devices, including but not limited to medical tubes, lines, bags, or other devices to maintain them and the solutions (fluids, gases, liquids, etc.) flowing through them to the patient in a warm state. 
     It should be understood that in the embodiments of  FIGS. 14-17 , the spunbond material  63  may be eliminated as the heating device  80  does not come into contact with a patient. However, the spunbond material  63  is still preferred as it helps to diffuse the heat for a more even heating of the medical device within the present heating device. 
     Thus, a heating device for warming medical solutions contained within a medical device, comprises an elongated first electrically insulative tube defining a medical solution tube channel, an elongated electrically resistive heating element tube mounted concentrically about or surrounding the first electrically insulative tube, an elongated second electrically insulative tube mounted concentrically about or surrounding the electrically resistive heating element tube, an elongated flexible metallic foil tube mounted concentrically about or surrounding the second electrically insulative tube, and an elongated thermoplastic tube mounted concentrically about or surrounding the flexible metallic foil tube. 
     It thus is seen that a metalized fabric heating device for medical solutions is now provided which overcomes problems associated with heating device of the prior art. It should of course be understood that many modifications may be made to the specific preferred embodiment described herein, in addition to those specifically recited herein, without departure from the spirit and scope of the invention as set forth in the following claims.