Patent Application
20070068916
The present invention pertains to flexible covers for heating units, for example, electric blankets, and more particularly to construction and manufacturing methods for such covers.
For over a decade, forced-air warming (FAW), via an inflatable air blanket, has been used in operating rooms to prevent hypothermia in surgical patients. It is well established that surgical patients under anesthesia become poikilothermic. This means that the patients lose their ability to control their body temperature and will take on or lose heat depending on the temperature of the environment. Since modern operating rooms are all air conditioned to a relatively low temperature for surgeon comfort, the majority of patients undergoing general anesthesia will lose heat and become clinically hypothermic, if not warmed. FAW has become the “standard of care” for preventing and treating the hypothermia caused by anesthesia and surgery. FAW consists of a large heater/blower attached by a hose to an inflatable air blanket. The warm air is distributed over the patient within the chambers of the blanket and then is exhausted onto the patient through holes in the bottom surface of the blanket. Although FAW is clinically effective, it suffers from several problems including: a relatively high price; air blowing in the operating room, which can be noisy and can potentially contaminate the surgical field; and the inflatable blanket is relatively bulky over the patient, at times even obscuring the view of the surgeon. Moreover, the low specific heat of air and the rapid loss of heat from air requires that the temperature of the air, as it leaves the hose, be dangerously high—in some products as high as 45° C. This creates significant dangers for the patient. Second and third degree burns have occurred both because of contact between the hose and the patient's skin, and by blowing hot air directly from the hose onto the skin, without connecting a blanket to the hose. This condition is common enough to have its own name—“hosing.” The manufacturers of forced air warming equipment actively warn their users against hosing and the risks it poses to the patient.
The logistics of forced-air warming and the bulk of the inflatable air blankets have motivated the development of electric or warm water circulating heating blankets. Many of these heating blankets are reusable so that the blankets must either be cleaned between uses, or the blankets must be enclosed in a clean cover for each use. Inadequate cleaning can cause cross contamination between patients. Cleaning is not only time consuming during the rapid turnover of the operating room after each case, but the labor for the cleaning is also expensive.
There is a need for heating blanket covers that are easily manipulated for placing a heating blanket therein and do not compromise the comfort of a person about which the blanket is placed. Since it is desirable that heating blanket covers be disposable, there is a need for cost-effective constructions, manufacturing methods and dispensing methods for such covers.
Certain embodiments of the present invention pertain to the construction of covers for flexible heating blankets. According to certain embodiments of the present invention, these covers include an upper flexible sheet, which is bonded to a lower flexible sheet, and an enclosure, which is disposed between the upper and lower sheets, for holding a flexible heating blanket; the enclosure includes one or more edges defined by one or more bonding sites of the upper sheet to the lower sheet. The upper sheet includes a panel, not adhered to, or being separable from, the lower flexible sheet, to provide an opening for the enclosure; the panel extends from a bonding site, or a first edge of the enclosure, to a free edge of the upper sheet. After folding back the panel to open the enclosure, a heating blanket may be laid down upon the lower sheet where it may be secured within the enclosure by closing the panel thereover; the panel may include a reversible fastening element to help secure the heating blanket within the enclosure.
Some cover embodiments include an upper flexible sheet that has a first panel and a second panel, each of the first and second panels not adhered to, or being separable from the lower flexible sheet, to provide the opening for the heating blanket enclosure. The first and second panels, according to these embodiments, when closed, extend toward one another from opposite edges of the enclosure, which may be defined by bonding sites of the upper flexible sheet to the lower flexible sheet, and may be opened by folding back in opposite directions. When closed, the first panel may overlap the second panel and one or both of the panels may include one or more reversible fastening elements to help secure the heating blanket within the enclosure beneath the panels. The fastening elements may be any one of a number of types known to those skilled in the art, for example hook and loop, snap-fit, button, tie strip, and adhesive (low or high tack) types.
Preferably, a lower flexible sheet of the cover has characteristics providing efficient heat transfer between the heating blanket enclosure of the cover and a person disposed beneath the lower sheet of the cover, while an upper flexible sheet of the cover has characteristics providing insulation and blood and fluid protection between the heating blanket enclosure and the area above the upper sheet. The lower flexible sheet of the cover may further provide a relatively soft interface for the person beneath the cover.
According to some embodiments of the present invention, the lower flexible sheet includes a first or bottom layer forming an outer surface of the cover and a second or top layer forming an inner surface of the heating blanket enclosure; the first layer, being formed of a fibrous material, woven or non-woven, is laminated with the second layer, which is formed of a polymeric material. Suitable laminating means include, but are not limited to, adhesive bonding, heat bonding and extrusion coating. Examples of suitable fibrous materials include, but are not limited to, polyester, polypropylene, nylon, rayon and cellulose, i.e. from wood pulp fibers; and examples of suitable materials for the second layer include, but are not limited to, polyethylene, polypropylene, polyolefin, ethylvinylacetate (EVA) and polyurethane. The upper sheet is formed of a polymer film or of a laminated material, similar to the lower sheet; according to preferred embodiments a heat sealing method is used to bond the upper sheet to the lower flexible sheet so that one or more bonding sites form a border for the enclosure, and a panel of the upper sheet is left non-adhered to the lower flexible sheet to form an opening for the enclosure. According to this preferred embodiment, the fibrous material of the first layer of the lower sheet has a melting point higher than that of either of the polymer of the second layer of the lower sheet or the polymer film forming the upper sheet.
According to some manufacturing methods of the present invention, a first length of laminated material, which includes a first layer of a fibrous material and a second layer of a polymeric material, is brought together with a second length of material, which may be a polymer film, or which may include first and second layers, similar to the first length of laminated material; if the second length is laminated, like the first length, the second and first lengths would be brought together so that the polymeric layers are adjacent one another. Preferably, a web-type manufacturing process is used to bring the two lengths of materials together, to bond the lengths together, and then to assemble the bonded lengths into a roll for the dispensing of individual covers. The process may further include a perforating step to segregate lengthwise segments of the length, each segment to form an individual cover, and thus increase the ease of dispensing.
According to some preferred embodiments of the present invention, bonding results in at least one lengthwise extending bond site formed between the first an second lengths, and bonding is accomplished via a heat sealing method, examples of which include, but are not limited to, thermal sealing, impulse sealing or dielectric or radio frequency sealing. A portion of the second length of material, which extends laterally from the at least one bond site over the first length, is left un-adhered to the first length such that a gap exists between the two lengths in order to form an enclosure being accessible via the portion of the second length which forms at least one panel.
According to a one-panel embodiment, the un-adhered portion extends laterally from the bonding site to a free edge of the second length of material. According to a two panel embodiment, approximately parallel bonds are formed on either side of the un-adhered portion and a slit is formed dividing the un-adhered portion into two panels that open away from one another. A slitting process may occur in line with the bonding process, either previously, simultaneously or subsequently, or may occur in a secondary operation after bonding. According to an alternate two-panel embodiment, a third length of material, along with the second length, is brought together with the first length of material and bonded thereto along a bonding site approximately parallel to the bonding site of the first length; an un-adhered portion of the third length extends laterally from the bonding site thereof, toward the un-adhered portion of the second length, to a free edge thereof, and, in some cases, overlaps the second length.
Fastening elements may be pre-formed, or attached, to one or all of first, second and third lengths of material. Alternately, for any of the embodiments, fastening elements may be formed on, or attached to, panels after the bonding process.
The following drawings are illustrative of particular embodiments of the present invention and therefore do not limit the scope of the invention. The drawings are not to scale (unless so stated) and are intended for use in conjunction with the explanations in the following detailed description. Embodiments of the present invention will hereinafter be described in conjunction with the appended drawings, wherein like numerals denote like elements.
FIGS. 1A-B are top and end views, respectively, of a heating blanket cover, according to some embodiments of the present invention.
FIGS. 2A-B are top and end views, respectively, of the blanket cover of FIGS. 1A-B enveloping a heating blanket.
FIGS. 3A-B are top and end views, respectively, of a heating blanket cover, according to some alternate embodiments of the present invention.
FIGS. 4A-B are top and end views, respectively, of the blanket cover of FIGS. 3A-B enveloping a heating blanket.
FIGS. 5A-C are sections illustrating a bonding detail between a laminated lower flexible sheet and an upper flexible sheet, according to preferred embodiments of the present invention.
The following detailed description is exemplary in nature and is not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the following description provides practical illustrations for implementing exemplary embodiments of the present invention. Examples of constructions, materials, dimensions, and manufacturing processes are provided for selected elements, and all other elements employ that which is known to those of skill in the field of the invention. Those skilled in the art will recognize that many of the examples provided have suitable alternatives that can be utilized.
FIGS. 1A-B are a top view and an end view of a heating blanket cover 100 according to some embodiments of the present invention. FIGS. 1A-B illustrate cover 100 including a lower flexible sheet 10 to which an upper flexible sheet 14 is bonded, in which upper flexible sheet 14 includes a first panel 15 and a second panel 150; bonding sites 16 and 160 of upper flexible sheet 14 may extend along a length L of panels 15, 150. Although bonding sites 16, 160 are illustrated having a generally narrow width, in alternate embodiments upper sheet 14 may extend further laterally over lower sheet 10, according to the arrows in
FIGS. 1A-B further illustrate a reusable heating blanket 1 disposed upon lower flexible sheet 10 within an enclosure 2 between bonding sites 16, 160. According to certain embodiments of the present invention, enclosure 2 is easily accessible by folding back panels 15, 150 of the upper sheet, as illustrated. FIGS. 2A-B are a top and end view of cover 100 wherein panels 15, 150 are closed over heating blanket 1; according to the illustrated embodiment, an overlap junction 19 of panels 15, 150 helps to secure heating blanket 1 within enclosure 2. According to some embodiments of the present invention, one or both of panels 15, 150 include one or more reversible fastening elements disposed in proximity to respective edges 17, 170; FIGS. 1A-B illustrate an embodiment wherein mating strips of fastening material 18 and 180, for example hook and loop type or adhesive type, extend along panel edges 17 and 170, respectively. FIGS. 2A-B further illustrate cover 100 including lateral portions or flaps 11 and 110 extending laterally beyond enclosure 2; according to certain embodiments of the present invention flaps 11, 110 are useful for holding heating blanket 1 in place over a patient, for example by tucking flaps 11, 110 around sides of the patient.
FIGS. 3A-B are a top view and an end view of a cover 200 according to alternate embodiments of the present invention.
FIGS. 4A-B further illustrate heating blanket 1 disposed upon lower flexible sheet 20 adjacent bonding site 36 which forms an edge of an enclosure 3 when panel 35 is closed over blanket 1, as illustrated in FIGS. 4A-B. From FIGS. 3A-B and 4A-B, the ease with which blanket 1 may be placed in enclosure 3, by first folding back panel 35 and then closing panel 35 over blanket 1, may be appreciated. Panel 35 may be reversibly fastened to lower sheet 20 in order to secure blanket 1 within enclosure 3; and FIGS. 3A-B illustrate a preferred embodiment in which a strip of fastening material 38, for example an adhesive strip, extends along length L′ of panel 35 in proximity to free edge 37. FIGS. 4A-B illustrate strip 38 of panel 35 adhered to lower flexible sheet 20 to secure blanket 1 within enclosure 3. According to alternate embodiments, lower sheet 20 and panel 35 include mating fastening elements, examples of which include, but are not limited to, hook and loop type, button type and snap-fit type.
FIGS. 4A-B further illustrate flaps 31 and 310 extending laterally beyond either side of enclosure 3. Similar to flaps 11, 110 of cover 100, flaps 31, 310 extend laterally over a sufficient length so that flaps 31, 310 may be tucked around sides of a patient on a bed or an operating table.
Preferably, a material or materials selected for upper flexible sheet 14 of cover 100 and upper flexible sheet 30 of cover 200 provides some thermal insulation, and potentially also protection against fluids, between heating blanket 1 and an area outside enclosures 2, 3, on an opposite side of upper sheet 14, 30, while a material or materials selected for lower flexible sheets 10, 20 allows efficient heat transfer therethrough between heating blanket 1 and patient disposed on an opposite side of lower sheets 10, 20. It is also preferable that lower flexible sheets 10, 20 of covers 100, 200 have sufficient flexibility to drape over and conform with contours of a patient, and, furthermore, include a relatively soft lower surface to make a comfortable interface with the patient.
According to certain embodiments of the present invention, lower flexible sheets 10, 20 are laminated and include a first layer of fibrous material, woven or non-woven, laminated with a layer of polymeric material. Examples of suitable fibrous materials include, but are not limited to, polyester, polypropylene, nylon, rayon and cellulose, i.e. from wood pulp fibers; and examples of suitable polymeric materials for the laminated layer include, but are not limited to, polyethylene, polypropylene, polyolefin, ethylvinylacetate (EVA) and polyurethane. Suitable laminating means include, but are not limited to, adhesive bonding, heat bonding and extrusion coating. The polymeric material layer of a laminated lower flexible sheet forms an upper surface on which heating blanket 1 would be laid, and to which an upper flexible sheet is bonded. The upper flexible sheet may be formed of a single layer of polymer film, or may also be laminated, including a layer of fibrous material overlaid with a polymeric material. The upper sheet is bonded to the lower flexible sheet, preferably, by a heat sealing method, for example thermal sealing, impulse sealing or dielectric or radio frequency sealing. According to this preferred embodiment, the fibrous layer of the lower flexible sheet has a melting point higher than the polymeric top layer of the lower sheet; and, likewise for the upper flexible sheet, if laminated, the fibrous layer having a higher melting point than the polymer overlay.
Heat sealing parameters for the exemplary embodiments of lower and upper sheets as described above are as follows: a temperature ranging from approximately 200° C. to approximately 1400° C.; a sealing speed ranging from approximately 50 feet/minute to approximately 200 feet/minute; and a sealing pressure ranging from approximately 50 to approximately 200 lb/linear inch of web width.
Since it is desirable that heating blanket covers be disposable, the embodiments shown in
In the foregoing detailed description, the invention has been described with reference to specific embodiments. However, it may be appreciated that various modifications and changes can be made without departing from the scope of the invention as set forth in the appended claims. Furthermore, although embodiments of the invention are described in the context of a hospital, particularly in an operating room, it is contemplated that the invention may be used in other environments.
The present application claims priority to co-pending Provisional Application Ser. No. 60/722,243, having the same title, and to co-pending Provisional Application Ser. No. 60/722,242 entitled COVER FOR A HEATING BLANKET, both of which are hereby incorporated by reference in their entireties. The present application is related to the commonly assigned utility application entitled, COVER FOR A HEATING BLANKET, filed concurrently herewith and incorporated by reference, in its entirety, herein.
| Number | Date | Country | |
|---|---|---|---|
| 60722243 | Sep 2005 | US | |
| 60722242 | Sep 2005 | US |
