STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT [0002] Not Applicable BACKGROUND OF THE INVENTION 1. Field of Invention [0003] This invention relates to a blanket for covering it least a portion of the body of a human, or other animal, in order to bath the body portion in a conditioned gas. More specifically, the present invention is related to an inflatable thermal blanket for providing a conditioned gas, such as, for example, heated air, to a selected portion of the body of a user and preventing the conditioned gas from being directed at other portions of the body.

2. Description of the Related Art [0004] Inflatable thermal blankets which are used to communicate a conditioned gas, such as heated or cooled air, to a patient are known in the art. Such thermal blankets typically have an inflatable portion provided with an inlet port for placing the inflatable portion in fluid communication with a source of pressurized, conditioned gas such that the inflatable portion can be selectively inflated. The inflatable portion generally has an inner surface which is gas pervious, or which is otherwise adapted to communicate the conditioned gas used to inflate the blanket to the user. Such thermal blankets are often used to treat conditions such as hypothermia, or used to reduce the body temperature of a user in circumstances where the body temperature is inappropriately high.

For example, where a patient is being treated for hypothermia, at least a portion of the patient's body is covered with the thermal blanket, and warm air is pumped into the inflatable portion. The warm air used to inflate the inflatable portion is thereafter communicated through the inner surface of the inflatable portion so as to bath the body portion covered by the blanket in warm air. Examples of such thermal blankets are disclosed in U. S. Patent Nos. 5,184, 612; 5,304, 213 ; and 5,324, 320.

Whereas prior art thermal blankets serve to deliver conditioned air to a patient, the temperature of the

air being communicated through the inner surface of the inflatable portion, and the surface temperature of the inner surface, can vary greatly over the area of the inner surface. For example, if heated air is pumped into the inflatable portion through the inlet port, the air within the blanket near the inlet port tends to be substantially higher in temperature than the air within the blanket which is remote from the inlet port. Accordingly, the inner surface of the blanket proximate the inlet port, and the air communicated to the patient through the inner surface of the blanket proximate the inlet port, can be uncomfortably, or damagingly, hot when the blanket is otherwise communicating air of the desired temperature to the patient. Whereas the temperature of the air entering the inlet port can be reduced to avoid uncomfortable, or damaging, hot spots near the inlet port, such a reduction of temperature can compromise the overall effectiveness of the thermal blanket.

[0005] Other devices for warming or cooling patients, and/or for communicating conditioned air to a patient, are disclosed in U. S. Patent Nos. 1,777, 982; 2,093, 834; 3,653, 083; 4, 347, 633 ; 4,472, 847; 4,572, 188; 4,660, 388; 4,777, 802; 5,106, 373; 5,165, 400; 5,300, 101 ; 5,300, 102; 5,336, 250; 5,350, 417; 5,405, 371; 5,545, 194; 5,674, 269; 5,860, 292 ; 6,102, 936; 6,210, 428 B1 ; and 6,228, 107 Bl. See also, PCT International ApplicationNo. PCT/US85/00071, and British Patent Nos. 716,746 ; 1 334 935; and 1 566 207.

BRIEF SUMMARY OF THE INVENTION [0006] The present invention provides an inflatable thermal blanket for providing a conditioned gas, such as, for example, heated air, to at least a portion of the body of a human or other animal. The thermal blanket includes an inflatable portion for receiving the conditioned gas under pressure and for being positioned over at least a portion of the body of the user. The inflatable portion is defined by a base sheet which is fabricated of a gas pervious material, or which is otherwise adapted for communicating the conditioned gas to a portion of the body, and by an outer sheet which is substantially gas impervious. The inflatable portion also includes an inlet port for placing the inflatable portion in fluid communication with a source of conditioned gas. The inflatable portion is constructed so as to direct the conditioned gas along a defined path inside the inflatable portion. The inflatable portion also includes a barrier sheet that is positioned adjacent the base sheet and which prevents the conditioned gas from passing through that portion of the base sheet so protected.

[0007] The inflatable portion includes at least a first channel and a second channel. The first channel receives the conditioned gas through the inlet port and routes the conditioned gas to the second channel. The conditioned gas in the first channel is not directly exhausted toward the patient because the barrier sheet is disposed between the base and outer sheets in the first channel. The

second channel receives the conditioned gas from the first channel and exhausts the conditioned gas towards the patient. The temperature of the conditioned gas is moderated by flowing within the first channel, thereby the conditioned gas that is exhausted toward the patient is at a moderated temperature, that is, the temperature of the exhausted conditioned gas is not at the same temperature as the conditioned gas at the inlet port. In one embodiment, small openings, or gaps, are located between the first and second channels, thereby allowing the temperature distribution of the conditioned gas in the second channel to be limited. Further, the openings allow for a more rapid inflation of the thermal blanket.

[0008] In another embodiment, the inflatable portion includes a third channel. The first channel is located parallel to, and between, the second and third channels. The conditioned gas enters the inlet port, flows along the first channel where its temperature is moderated, and then enters the second and third channels, where the gas is exhausted through the base sheet.

[0009] In still another embodiment, the inflatable portion includes a third channel and a second barrier sheet. The first channel is located parallel and adjacent to the second channel, which is adjacent to the third channel. The first barrier sheet lines the first channel and the second barrier sheet lines the third channel. The conditioned gas enters the inlet port, flows along the first channel where its temperature is moderated, and then enters the second and third channels, where the gas is exhausted through the base sheet in the second channel, but not the third channel.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS [0010] 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: Figure 1 is a side elevation view of one embodiment of an inflatable thermal blanket; Figure 2 is a perspective view of the inflatable thermal blanket; Figure 3 is an exploded perspective view of the inflatable thermal blanket; Figure 4 is a top plan view of the inflatable thermal blanket illustrating the flow paths; Figure 5 is a top plan view of an embodiment of a pediatric inflatable thermal blanket; Figure 6 is a top plan view of an embodiment of a lower body inflatable thermal blanket; Figure 7 is a top plan view of a prior art barrier sheet;

Figure 8 is a top plan view of an embodiment of an upper body inflatable thermal blanket; Figure 9 is a top plan view of another embodiment of an upper body inflatable thermal blanket; Figure 10 is a top plan view of an embodiment of a neonatal inflatable thermal blanket.

DETAILED DESCRIPTION OF THE INVENTION [0011] An inflatable thermal blanket in accordance with the present invention is illustrated generally at 10 in Figures 1-5. The thermal blanket 10 is designed to cover at least a portion of the body of a human 106, or other animal, and to bath at least a portion of such body with a conditioned gas, such as thermally conditioned air. The thermal blanket 10 is particularly useful in bathing a body portion in air which has been heated to a temperature above normal body temperature in order to treat conditions such as hypothermia. However, it will be understood that gaseous fluids other than air can be used, and in certain applications the gaseous fluid utilized may be delivered to the body portion at a temperature which is at, or lower than, normal body temperature, as in the case where the existing body temperature is abnormally high and cooling is desired.

[0012] Figure 1 illustrates the thermal blanket 10, which includes a first or base sheet 102, at least a portion or portions, of which are pervious to gaseous fluids such as air. Preferably the base sheet 102 is fabricated of a natural, or synthetic, non-woven material through which air under pressure can be communicated. The base sheet 102 is draped over the patient 106 in order to help retain the conditioned gas communicated to the patient beneath the base sheet 102 and around the patient 106. Attached to the base sheet 102 is a second or outer sheet 104, which is fabricated of a substantially gas impervious material. The base sheet 102 and the outer sheet 104 are joined at a seam 114 and define an inflatable portion 108.

[0013] A blower 122 supplies a conditioned gas to the inflatable portion 108 via a flexible conduit 128. The conduit 128 connects to an inlet port 120, which is defined by a reinforcing collar 124 attached to the second sheet 104. The inlet port 120 serves the function of introducing the conditioned gas into the inflatable portion 108. The blower 122 forces conditioned gas into the inflatable portion 108 and the conditioned gas exhausts through selected portions of the base sheet 102 towards the patient 106. The conditioned gas, in one embodiment, is heated air that is used to increase or maintain the body temperature of the patient 106. In another embodiment, the conditioned gas is cooled air that is used to decrease or maintain the body temperature of the patient 106.

[0014] Figure 2 illustrates the thermal blanket 10 in a flat, inflated position. In this position, the notch, or cutout portion, 212 into which the head of the patient 106 fits is illustrated. Also illustrated are the additional connection or securing points 222A, B, 224A, B, 226A, B, and 228A, B in which the base sheet 102 is attached to the outer sheet 104 by heat bonding. A barrier sheet 232 orientated longitudinally with the thermal blanket 10 is positioned between the base sheet 102 and the outer sheet 104. The base sheet 102 is wider than the outer sheet 104. When the thermal blanket 10 is in use the base sheet 102 drapes over the shoulders and feet of the patient 106 and over the sides of the patient 106 in order to help retain the conditioned gas communicated to the patient 106 beneath the base sheet 102 and around the patient 106.

[0015] In the illustrated embodiment the baffle 232 has the same length as the base sheet 102, which facilitates manufacture of the thermal blanket 10, and it will be recognized that a baffle 232 which extends only the length of the inflatable portion 108, or along a portion of the length of the inflatable portion 108, could be used. Similarly, in order to facilitate manufacture, the outer sheet 104 extends the length of the base sheet 102, but it will be recognized that the outer sheet 104 need only be of sufficient length to form the outer wall of the inflatable portion 108.

[0016] The base sheet 102, the outer sheet 104, and the barrier sheet 232 are heat bonded together within the inflated portion 108 of the blanket 10 at intermittent seams 202,204, 206. The base sheet 102 and the outer sheet 104 are heat bonded together within the inflated portion 108 of the blanket 10 at intermittent seams 208,210. The seams 114,202, 204,206, 208,210, 222A, B, 224A, B, 226A, B, 228A, B are formed by heat bonding in one embodiment. Those skilled in the art will recognize that various adhesive or other bonding methods can be used without departing from the spirit or scope of the present invention.

[0017] Figure 3 is an exploded view of the thermal blanket 10. The base sheet 102 is a substantially rectangular sheet fabricated of an air permeable material, such as, for example, a natural or synthetic non-woven material through which air under pressure can be communicated. Whereas synthetic materials such as, for example, polyester, can be used, the use of a cellulose or paper based material has advantages where a single use, disposable thermal blanket 10 is desired. In another embodiment, the base sheet 102 is fabricated of an air impermeable material that is provided with openings through which gas can pass. In still another embodiment, the base sheet 102 is fabricated of a material that is air permeable in selected areas and otherwise air impermeable. The outer sheet 104 is a substantially rectangular sheet fabricated out of an air impermeable material, such as, for example, a cellulose based sheet material coated with a film of polyethylene or polypropylene.

Between the base sheet 102 and the outer sheet 104 is a barrier sheet 232. The barrier sheet 232 is a

substantially rectangular sheet fabricated out of an air impermeable material, such as, for example, a sheet of polyethylene or polypropylene.

[0018] A reinforcing collar 124 for the inlet port 120 has an opening 126 for receiving the end of the supply hose 128. The collar 124 is secured to the outer sheet 104 with an adhesive. The opening 126 is approximately 2-1/4 inches in diameter. In one embodiment, the outer sheet 104 does not have a corresponding opening in the outer sheet 104. When the thermal blanket 10 is used, the portion of the outer sheet 104 within the opening 126 is torn to allow the insertion of the end of the hose 128.

[0019] Each of the sheets 102,104, 232 have a notch, or cutout portion, 312A, 312B, 312C, which is sized to fit around the neck and chin of the patient 106. The three sheets 102,104, 232 are secured together by a series of securing points 222A, B, 224A, B, 226A, B, and 228A, B, the seam 114, and a plurality of intermittent seams 202,204, 206,208, and 210, shown in phantom on the outer sheet 104. The series of securing points 222A, B, 224A, B, 226A, B, and 228A, B serve the function of securing the edges of the outer sheet 104 to the base sheet 102. The seam 114 serves the function of forming an air-tight seal between the outer sheet 104 and the base sheet 102. The plurality of intermittent seams 202,204, 206,208, and 210 serve the function of forming channels 442,444, 446 (illustrated in Figure 4) and of directing the conditioned gas within the inflatable portion 108.

[0020] Figure 4 illustrates a plan view of the thermal blanket 10. The flow paths 402,404, 406,408 of the conditioned air entering through the inlet port 120 are illustrated. Two intermittent seams 204,206 form an inside channel 442 through which a flow path 402 is defined. The intermittent seam 202 divides the inside channel 442 into two sections 442A, 442B. The intermittent seam 204 and the outside seam 114 form a first outside channel 444, which is divided into two sections 444A, 444B by intermittent seam 208. The intermittent seam 206 and the outside seam 114 form a second outside channel 446, which is divided into two sections 446A, 446B by intermittent seam 210. The dividing intermittent seams 202,208, 210 serve to prevent the channels 442,444, 446 from assuming a large diameter when inflated and allow the thermal blanket to better drape about the patient 106.

[0021] In operation, the conditioned gas enters the inlet port 120 and flows 402 along the inner channel 442. Because the baffle sheet 232 is adjacent the base sheet 102 and opposite the inlet port 120, the pressure of the conditioned gas forces the baffle sheet 232 against the base sheet 102, thereby preventing the conditioned gas from exiting through the base sheet 102 along the inside channel 402. The conditioned gas flows 402 along the inside channel 442 towards the head of the

patient 106, which is located within the cutout portion 212. The conditioned gas flows 402 into the two outside channels 444,446, where the conditioned gas flows 404,408, 406,408 back toward the foot of the thermal blanket 10. The conditioned gas inside the outside channels 444,446 is exhausted through the base sheet 102 because the base sheet 102 is not restricted by the baffle sheet 232 in the area of the outside channels 444,446.

[0022] In one embodiment, the conditioned gas is heated air. The heated air entering the inflated portion 108 at the inlet port 120 is allowed to disperse and cool as it travels down the inside channel 442 without the heated air being immediately communicated to the patient 106. When the heated air is subsequently communicated into the outside channels 444,446, it is more evenly dispersed and the temperature of the air being communicated to the patient through the base sheet 102 is more consistent over the area encompassed by the length of the outside channels 444,446.

Consequently, by providing the inside channel 442 to disperse the incoming air before it is communicated to the patient the area of increased temperature proximate the inlet port 120 typical of prior art thermal blankets is avoided. Of course, in the embodiment where the conditioned gas being used is air which has been cooled below body temperature, the inside channel 442 also facilitates dispersal of the air into the outside channels 444,446 such that the temperature of the air being communicated to the patient 106 through the base sheet 102 is more consistent over the area encompassed by the length of the outside channels 444,446.

[0023] More particularly, the heated air, as it enters the inlet port 120 and flows 402 along the inside channel 442 is not exhausted toward the patient 106. The heated air is exhausted toward the patient 106 after it enters the two outside channels 444, 446 ; however, the heated air cools as it travels along the channels 442,444, 446. The gaps along the intermittent seams 204,206 allow a small amount of the heated air from the inside channel 442 to enter the outside channels 444,446, thereby ensuring that the air temperature in the outside channels 444,446 is relatively constant along the length of the outside channels 444,446. Accordingly, the intermittent seams 204,206 separating the inside channel 442 from the outside channels 444,446 have the function of maintaining a substantially constant temperature along the outside channels 444,446. Secondarily, the intermittent seams 204,206 also have the function of aiding the rapid inflation of the inflatable portion 108 by allowing multiple paths for the conditioned gas to reach the furthest regions of the inflatable portion 108 of the thermal blanket 10.

[0024] In another embodiment, the gaps in the intermittent seams 204,206 are omitted in which significant cooling of the heated air takes place before the air is dispersed from the outside channels 444,446 into the inside channel 442. Whereas for certain applications this cooling may be desirable, for other applications it may be appropriate to maintain a higher temperature in the outside

channels 444,446. Accordingly, by reducing, or eliminating the small gaps in the intermittent seams 204,206, fluid flow into the outside channels 444,446 can be limited, thereby resulting in a greater moderation of the temperature of the gas communicated from the inside channel 442 to the outside channels 444,446.

[0025] Figure 5 illustrates another embodiment of the thermal blanket 510. This embodiment is suitable for pediatric applications, accordingly, the base sheet 502, the outer sheet 504, and the barrier sheet 532 are shorter than the corresponding sheets 102,104, 252 illustrated in Figures 1-4. The overall volume and length of the outside channels 544,546 of the thermal blanket 510 are reduced in view of the fact that the blanket 510 is intended for use with pediatric patients.

Due to the this smaller volume and reduced length, the blanket 510 is provided with seams 514,516 that are continuous. The absence of gaps in the seams 514,516 serves to retain the conditioned gas in the inside channel 542 over the length of the channel 542 to allow the temperature of the gas to moderate, thereby compensating for the smaller volume and shorter length of the outer channels 544, 546.

[0026] Securing points 522A, B, 524A, B, 526A, B, and 528A, B attach the base sheet 502 to the outer sheet 504 by heat bonding. A barrier sheet 532 orientated longitudinally with the thermal blanket 510 is positioned between the base sheet 502 and the outer sheet 504. An inflatable portion 508 is defined by the seam 554.

[0027] In this pediatric embodiment, the seams 514,516 separating the inside channel 542 from the outside channels 544,544 do not have any gaps; therefore, conditioned gas entering the inlet port 520 flows along the inside channel 542 toward the cutout 562 into which the pediatric patient's head fits, and into the outside channel 544,546. By not having gaps in the seams 514,516, in the embodiment in which the conditioned gas is heated air, the air in the outside channels 544,546 is not mixed with the air flowing in the inside channel 542; therefore, the air temperature in the outside channels 544,546 is much cooler than the temperature of the air at the inlet port 120. The intermittent seams 518,520 in the outside channels 544,546 have large gaps through which the conditioned gas flows to ensure homogeneous mixing of the gas between the divided outer channels 544A, B, 546A, B.

[0028] Figure 6 illustrates another embodiment of the thermal blanket 610. This embodiment is adapted to be particularly useful in bathing the lower body of a human patient in conditioned gas. In this regard, instead of a cutout portion 212 for the neck of the patient 106, the lower body thermal blanket 610 is provided with a securing strip 652, which extends across one edge of the base sheet 102 and which is provided with an adhesive (not shown) on the side facing the

patient 106 to allow the thermal blanket 610 to be releasably secured to the patient 106 and/or the bed on which the patient 106 is lying, as the inflatable portion 608 covers the lower portion of the body of the patient 106.

[0029] The embodiment illustrated in Figure 6 utilizes similar construction as the embodiment illustrated in Figure 5, namely, seams 614,616 separating the inside channel 642 from the outside channels 644,646 are continuous. The inside channel 642 dividing seam 612 is intermittent because the overall length of this embodiment is slightly longer than the pediatric thermal blanket 510. The barrier sheet 632 prevents the conditioned gas from being exhausted through the base sheet 602 in the inside channel 642.

[0030] Figure 7 illustrates a prior art barrier sheet 732 for an upper body thermal blanket.

The barrier sheet 732 is fabricated of an air impermeable material, such as a plastic sheet, and has a plurality of openings 702 cut into the sheet 732. The function of the prior art barrier sheet 732 is to uniformly restrict the air flow through an air permeable sheet, thereby increasing the back-pressure in the thermal blanket. The increased back-pressure allows the thermal blanket to be fully inflated.

Without the prior art barrier sheet 732, the thermal blanket will not fully inflate if either the air permeable sheet passes too great a volume of air or the blower 122 does not develop sufficient pressure for the volume of air exhausting through the air permeable sheet. A disadvantage of the prior art barrier sheet 732 includes additional fabrication steps to punch the openings 702. A further disadvantage is that the discrete openings 702 result in the conditioned gas being exhausted in discrete areas and not over the entire surface of the air permeable sheet. Because the exhausted gas passes through a smaller area of the air permeable sheet, the gas has a greater velocity for similar air flows, thereby the patient experiences impinging gas flow resulting in uneven heating or cooling, depending on whether the conditioned gas is heated or cooled. Conditioned gas that is permitted to exhaust over a wide area of the air permeable sheet evenly bathes the patient in the conditioned gas and does not locally impinge the patient with gas.

[0031] Figure 8 illustrates another embodiment of the thermal blanket 810. The illustrated upper body thermal blanket 810 is adapted to provide conditioned gas to the upper body, including the extended arms, of the patient 106. The thermal blanket 810 is provided with a cutout portion 818A for receiving the neck of the patient 106, and opposite the cutout portion 818A is a torso cutout 818B, which is provided with securing strips 862A, 862B, which in the illustrated embodiment are provided with an adhesive on the side facing the patient 106, for releasably securing the thermal blanket 810 to the patient 106. Accordingly, the inflatable portion 108 extends laterally across the upper torso and along the length of both arms so as to allow these portions of the body to be bathed

in a conditioned gas which is communicated from the inside channels 844,846 through the base sheet 102.

[0032] The upper body thermal blanket 810 includes two inlet ports 120,120', which can be used, in one embodiment, simultaneously by connecting each inlet port 120, 120'to a blower 122. In another embodiment, only a single inlet port 120, 120'is used. In this embodiment, the reinforcing collars 124, 124'are attached to the upper sheet 804, which does not have an opening cut into it corresponding to the opening 126, 126'in the collar 124,124'. The outer sheet 804 adjacent the opening 126, 126' associated with the desired inlet port 120, 120'to be used is torn when the flexible hose 128 is to be inserted in the inlet port 120,120'. Accordingly, a single port 120, 120'is used without having the conditioned gas escape through the unused inlet port 120', 120.

[0033] In the embodiment in which only a single inlet port 120 is used, the conditioned gas flows 852A, B, C, D through a first channel 842 formed between the seal 864 defining the inflatable portion 808 and the seam 812A, B. The conditioned gas then flows 854A, B into a second channel 844, which is defined by the seam 812A, B and the intermittent seam 816A, B, and the gas flows 858A, B into a third channel 846, which is defined by the intermittent seam 816A, B, and the seal 864. The opening between the intermittent seam 816A, 816B permits the conditioned gas to mix between the second and third channels 844,846.

[0034] The barrier sheets 832A, B prevent the conditioned gas from passing through the base sheet 802 in the first and third channels 842,846. Accordingly, the conditioned gas is exhausted through the base sheet 802 in the area of the second channel 844, which is divided into two sections 844A, 844B by the intermittent seam 814. With the arms of the patient 106 preferably being positioned beneath the more centrally located second channel 844, the conditioned gas is exhausted and concentrated on the arms of the patient 106.

[0035] In one embodiment the conditioned gas is heated air and the barrier sheet 832A prevents the heated air from being immediately exhausted to the patient 106. The heated air cools as it flows 852A, B, C, D, 854A, B into the second channel 844 and is exhausted toward the patient 106. The second barrier sheet 832B in the third channel 846 prevents air from being exhausted. The air in the third channel 846 has cooled the most and would result in too cool air being directed toward the patient 106 if not for the second barrier sheet 832B. Unlike the prior art barrier sheet 732, which restricts the air flow throughout the area of the base sheet, the barrier sheets 832A, B prevent air flow in specific regions of the thermal blanket 810, thereby allowing the heated air to cool and be evenly mixed for exhausting through a specific region, namely the second channel 844.

Additionally, in the illustrated embodiment, the conditioned gas is exhausted over the entire surface

of the second channel 844, resulting in the patient receiving the conditioned gas evenly over an extended surface area. With the prior art barrier sheet 732, the conditioned gas is exhausted only through the openings 702 and not over the entire surface of the base sheet.

[0036] Figure 9 illustrates another embodiment of an upper body thermal blanket 910 in which the inflatable portion 908 covers the torso and one arm of the patient 106. The upper body thermal blanket 910 has two cutout portions 918A, B for receiving the neck of the patient 106. If the patient's 106 left arm is to be covered by the blanket 910, one cutout portion 918A fits about the neck of the patient 106. If the other arm is to be covered, the blanket 910 is rotated such that the other cutout portion 918B fits about the neck of the patient 106. Two inlet ports 120, 120'are provided to alternatively access the outer channel 942 or 946 in order to facilitate the convenient connection of the blanket to a source of conditioned gas.

[0037] The inflatable portion 908 has three channels 942,944, 946 defined by the seam 954 and the two intermittent seams 912,916. A third intermittent seam 914 divides the inner channel 944 into two sections. The outer channels 942,946 have a barrier sheet 932A, B that prevents the conditioned gas from the inlet ports 120, 120'from immediately being exhausted from the base sheet 902. The conditioned gas is exhausted through the base sheet 902 in the inner channel 944, at which point the temperature of the conditioned gas has moderated by flowing through the outer channel 942,946 nearest to the inlet port 120, 120'being used. The opposite outer channel 946,942 does not exhaust the conditioned gas because of the barrier sheet 932A, 932b.

[0038] Figure 10 illustrates an embodiment of a neonatal thermal blanket 1010. The neonatal thermal blanket 1010 is constructed so as to limit the flow of conditioned gas communicated through the base sheet 1002 directly over the infant in order to avoid inappropriately rapid changes in body temperature. A cutout portion 1012 receives the neck of the infant and the inlet port 120 is located at the opposite end. A barrier sheet 1032 covers a major portion of the base sheet 1002, thereby limiting the conditioned gas to being exhausted at the edges of the inflatable portion 1008 away from the body of the infant.

[0039] The conditioned gas enters the inlet port 120 and flows into two outer channels 1042,1044 and into a central channel, or chamber, 1046. The central channel 1046 is more properly called a central chamber 1046 because the conditioned gas enters the chamber, but without an exit, the conditioned gas remains in the chamber 1046. The central chamber 1046 has a plurality of seams 1052 that minimize the inflated height of the central chamber 1046. The temperature of the conditioned gas in the two outer channels 1042,1044 is moderated by the distance the gas has to travel and by the limited surface area of the base sheet 1002 through which the conditioned gas is

exhausted. In this regard, the infant is preferably positioned beneath the central chamber 1046, with the outer channels 1042,1044 providing indirect gas flow to the infant.

[0040] In the present invention, the base sheet 102,502, 602,802, 902,1002 performs the function of exhausting a gas from the inflatable portion of the thermal blanket 10,510, 610,810, 910,1010 towards the patient 106. The barrier sheet 232,532, 632,832A, 832B, 932A, 932B, 1032 performs the function of blocking the conditioned gas from being exhausted through the base sheet 102,502, 602,802, 902,1002. The outer sheet 104,504, 604,804, 904,1004, in addition to the boundary seam 114,554, 654,854, 954,1054, performs the function of containing the conditioned gas in an inflatable portion 108,508, 608,808, 908,1008 of the thermal blanket. The seams 114, 204,206, 554,504, 506,654, 604,606, 854,812, 816,954, 912,916, 1054, perform the function of forming the various channels in the inflatable portion 108,508, 608,808, 908,1008.

[0041] The present invention provides a thermal blanket having an air permeable base sheet, at least one air impermeable barrier sheet, an air impermeable outer sheet, and an inlet port.

The three sheets are bonded together to form an inflatable portion. The barrier sheet is positioned between the base sheet and the outer sheet such that when a conditioned gas is introduced into the inflatable portion, the barrier sheet is forced against selected portions of the base sheet and prevents the conditioned gas from passing through the base sheet adjacent the barrier sheet.

[0042] The inflatable portion is divided into at least a first channel and a second channel.

The first channel receives the conditioned gas through the inlet port and routes the conditioned gas to the second channel. The conditioned gas in the first channel is not directly exhausted toward the patient because the barrier sheet is disposed between the base and outer sheets in the first channel.

The second channel receives the conditioned gas from the first channel and exhausts the conditioned gas towards the patient. The temperature of the conditioned gas is moderated by flowing within the first channel, thereby the conditioned gas that is exhausted toward the patient is at a moderated temperature, that is, the temperature of the exhausted conditioned gas is not at the same temperature as the conditioned gas at the inlet port.

[0043] The channels are formed by seams between the base sheet and the outer sheet. The first channel includes a third sheet, the barrier sheet, which prevents the conditioned gas from being exhausted through the base sheet. In one embodiment, small openings, or gaps, are located in the seams between the first and second channels, thereby allowing the temperature distribution of the conditioned gas along the second channel to be maintained more evenly. Further, the openings allow for a more rapid and consistent inflation of the thermal blanket. The size and number of the

openings is determined by the size of the inflatable portion and the need to maintain the temperature distribution along the second channel within narrow limits.

[0044] In one embodiment, a third channel is created in the inflatable portion. This third channel is located at an extreme end of the inflatable portion, relative to the inlet port. The third channel has a second barrier sheet, which prevents the third channel from exhausting conditioned gas toward the patient. The third channel has the function of increasing the inflated area of the inflatable portion and of preventing the exhausting of conditioned gas that has been too cooled or heated, depending upon whether the conditioned gas is heated or cooled. This ensures that the conditioned gas being exhausted through the base sheet is maintained within a narrow temperature range.

[0045] In light of the above, it will be recognized that the present invention provides a thermal blanket with significant advantages over the prior art. Prior art thermal blankets typically communicate an air flow to the patient which is uneven in temperature, and where heated air is being communicated, such blankets can generate hot spots proximate the point at which the heated air is pumped into the blanket. The unique construction of the thermal blanket of the present invention obviates such hot spots, while at the same time allowing the volume and the temperature of the air flow communicated to the patient to be controlled by the selective placement of barrier sheets and gaps in the seams between the channels.

[0046] 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.