Abstract:
Prevention or treatment of hypothermia in a person is afforded by an inflatable cover with a surface for expelling air from the cover. A heater/blower unit is connected to the cover to inflate the cover with warmed air and to maintain the temperature of warmed air expelled through the surface in a range of 85.2° F. to 117.7° F. The heater/blower unit may also maintain the temperature of warmed air provided to inflate the cover in a range of 113.3° F. to 121.3° F. The heater/blower unit may also maintain the temperature of warmed air under the surface in a range of 103.8° F. to 112.5° F. A pattern of apertures in the surface or vents in sides of the inflatable cover may be provided in order to circulate the warmed air to edges of the inflatable cover.

Description:
RELATED APPLICATIONS 
     This is a continuation of U.S. patent application Ser. No. 09/334,160, filed Jun. 16, 1999, now U.S. Pat. No. 6,210,428, which is a divisional of U.S. patent application Ser. No. 08/859,891, filed May 21, 1997, now U.S. Pat. No. 5,968,084, which is a continuation of U.S. patent application Ser. No. 08/419,719 filed Apr. 10, 1995, which is a continuation of U.S. patent application Ser. No. 07/638,748 filed Jan. 8, 1991, now U.S. Pat. No. 5,405,371, which is a continuation-in-part of Ser. No. 07/550,757, filed Jul. 10, 1990, now abandoned, which is a continuation-in-part of U.S. patent application Ser. No. 07/227,189, filed Aug. 2, 1988, now abandoned, which is a continuation-in-part of U.S. patent application Ser. No. 07/104,682, filed Oct. 5, 1987, now abandoned. 
     This application contains material related to the following pending U.S. Patent Applications and issued patents, all assigned commonly with this application: 
     U.S. Ser. No. 07/703,592, filed May 20, 1991, now U.S. Pat. No. 5,324,320 for THERMAL BLANKET; 
     U.S. Ser. No. 07/890,554, filed May 28, 1992, now U.S. Pat. No. 5,184,612 for THERMAL BLANKET WITH TRANSPARENT UPPER BODY DRAPE; 
     U.S. Ser. No. 08/014,619, filed Feb. 8, 1993, now U.S. Pat. No. 5,336,250 for THERMAL BLANKET WITH TRANSPARENT UPPER BODY DRAPE; 
     U.S. Ser. No. 08/388,730, filed Feb. 15, 1995, now U.S. Pat. No. 5,620,482 for INFLATABLE THERMAL BLANKET WITH A FOOT DRAPE; 
     U.S. Ser. No. 08/525,407, filed Sep. 8, 1995, now U.S. Pat. No. 6,126,393, for LOW NOISE AIR BLOWER UNIT FOR INFLATING THERMAL BLANKETS; 
     U.S. Ser. No. 08/531,772, filed Sep. 21, 1995, now U.S. Pat. No. 5,773,275, for INFLATABLE THERMAL BLANKET WITH PROVISION FOR BEING SECURED DURING USE; 
     U.S. Ser. No. 08/575,774, filed Dec. 20, 1995, now U.S. Pat. No. 5,697,963, for A THERMAL BLANKET FOR A PATIENT SITTING IN A CHAIR; 
     U.S. Ser. No. 08/691,593, filed Aug. 2, 1996, now U.S. Pat. No. 5,733,318, for CONVERTIBLE THERMAL BLANKET; 
     U.S. Ser. No. 08/667,480, filed Jun. 24, 1996, now U.S. Pat. No. 5,658,325, for CONVECTIVE THERMAL BLANKET; 
     U.S. Ser. No. 08/756,959, filed Dec. 3, 1996, now abandoned, for THERMAL BLANKET; 
     U.S. Ser. No. 08/831,603, filed Apr. 10, 1997 for THERMAL BLANKET WITH A DRAPE; 
     U.S. Ser. No. 08/855,061, filed May 13, 1997 for THERMAL BLANKET; 
     U.S. Ser. No. 08/846,089, filed May 16, 1997, now U.S. Pat. No. 6,287,327, for THERMAL BLANKET; 
     U.S. Ser. No. 08/867,092, filed Jun. 2, 1997, now U.S. Pat. No. 5,941,907, for SURGICAL BARRIER DEVICE INCORPORATING AN INFLATABLE THERMAL BLANKET WITH A SURGICAL DRAPE TO PROVIDE THERMAL CONTROL AND SURGICAL ACCESS; 
     U.S. Ser. No. 09/780,285, filed Feb. 21, 2001, for SYSTEM AND METHOD FOR WARMING A PERSON TO PREVENT OR TREAT HYPOTHERMIA; and 
     U.S. Ser. No. 09/802,642, filed Mar. 9, 2001, for INFLATABLE DEVICE WITH EXHAUSTING APERTURES WHICH VERY IN DENSITY. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to thermal blankets used in a medical setting to deliver a bath of a thermally-controlled medium to a patient. 
     The thermal blanket prior art is best expressed in our prior U.S. Pat. No. 4,572,188 entitled “AIRFLOW COVER FOR CONTROLLING BODY TEMPERATURE.” In our prior patent, a self-erecting, inflatable airflow cover is inflated by the introduction into the cover of a thermally-controlled inflating medium, such as warmed air. When inflated, the cover self-erects about a patient, thereby creating an ambient environment about the patient, the thermal characteristics of which are determined by the temperature of the inflating medium. Holes on the underside of our prior art airflow cover exhaust the thermally-controlled, inflating medium from inside the cover to the interior of the erected structure. Our airflow cover is intended for the treatment of hypothermia, as might occur postoperatively. 
     Evaluation of our airflow cover by skilled practitioners has resulted in general approbation: the opinion is that the airflow cover efficiently and effectively accomplishes its purpose of giving a thermally-controlled bath. We have realized, however, that, while our prior art airflow cover achieves its objective, certain improvements to it are necessary in order to realize additional clinical objectives and to enjoy further advantages in its use. 
     SUMMARY OF THE INVENTION 
     We have improved the clinical usefulness of our self-erecting airflow cover by observing that controlling the contour of its inflatable portion at its head end to define a generally concave non-inflatable portion will permit a care giver to more easily observe a patent&#39;s head, face, neck and chest. Further, we have observed that limited venting of the thermally controlled inflating medium from the edges of the cover results in more efficient, more uniform heating within the cover. We have also observed that it is good clinical practice to keep the area of the care site in the vicinity of the patient&#39;s head and face as clean as possible. Still further, we have observed that modification of the foot end of the self-erecting airflow cover to define a non-inflatable but erectable drape section retains heat from the inflating medium to warm the patient&#39;s feet and insulate the bare skin of the feet from excessive heat from the inlet hose. Finally, we have observed that our self-erecting airflow cover may be advantageously adapted to thermally control specific partial portions of the patient such as the legs and lower body or the arms and upper body, leaving other areas of the patient available for care and treatment. Moreover, an end portion of the cover may be adhesively attached to the patient to prevent the migration of air toward a care area. Finally, a protective sleeve may be slideably mounted on a connected heater tube adjacent the patient to prevent the heater tube from contacting the patient. 
     These observations have resulted in an improved thermal blanket and method therefor in which a self-erecting inflatable covering has a head end, a foot end, two edges, and an undersurface. An inflating inlet adjacent the foot (or head) end admits a thermally-controlled inflating medium into the covering. An aperture array on the undersurface of the covering exhausts the thermally controlled inflating medium from the covering into the structure created when the covering self-erects upon inflation. The improvements to this basic structural complement include an uninflatable section at the head (or foot) end of the covering, exhaust port openings at the edges of the covering, an absorbent bib or adhesive strip attached to the covering at the head (or foot) end adjacent the uninflatable section, an uninflatable erectable drape section at the foot end of the covering, a heater tube protective cover and structural features that make the covering simple and economical to produce. In the case of an upper body covering, the positions of the inflating inlet and the uninflatable section are reversed from that of other coverings. In the case of an upper body covering, the inflating inlet is positioned at the head end of the covering while the uninflatable section is arranged at the foot end of the covering. 
     With these improvements, the thermal blanket, when inflated and erected over a patient, delivers the thermally-controlled inflating medium into the interior of the structure covering the patient, thereby thermally bathing the patient. The first improvement permits full viewing of the head and face of the patient from almost any aspect around the thermal blanket. The exhaust port openings increase the rate of circulation of the inflating medium within the blanket, thereby increasing the temperature within the structure and making the temperature distribution more uniform. The absorbent bib soaks up and retains liquids which might otherwise spread over the care site in the area of a patient&#39;s head or other body area. Such liquids can include the patient&#39;s own perspiration, blood, vomit, saliva, or liquids which are administered to the patient. The adhesive strip acts to seal the head (or foot) end of the inflated structure. The non-inflatable erectable drape section at the foot end of a covering encompassing the lower extremities retains heat around the patient&#39;s feet and insulates the bare skin of the legs and/or feet. The protective cover for the heater tube prevents an attached heater tube from contacting the patient. 
     From another aspect, the invention is a thermal blanket for covering and bathing a person in a thermally-controlled medium. The thermal blanket includes a flexible base sheet having a head end, a foot end, two edges, and a plurality of apertures opening between the first and second surface of the base sheet. An overlying material sheet is attached to the first surface of the base sheet by a plurality of discontinuous seams which form the material sheet into a plurality of substantially parallel, inflatable chambers. A continuous seam is provided between the material sheet and the base sheet at the head (or foot) end to form a non-inflatable viewing recess at the head (or foot) end. Exhaust port openings are provided through the material sheet to vent the medium from the chambers away from the base sheet. An absorbent bib is attached to the head (or foot) end in the vicinity of the viewing recess. 
     In coverings encompassing the lower extremities, a continuous seam is provided between the material sheet and the base sheet at the foot end to form a non-inflatable, erectable drape section to cover the patient&#39;s legs and/or feet. 
     Therefore the invention accomplishes the important objective of providing a self-erecting, inflatable thermal blanket that permits a relatively unobstructed view of a care site when in use. 
     Another objective is the efficient and uniform heating of the interior of the structure created when the blanket is inflated with a heat inflating medium. 
     A further objective is providing a covering for a patient&#39;s legs and/or feet that helps retain the heat inflating medium around the patient. 
     A still further objective is the provision of such a blanket with a means for maintaining the cleanliness of the care site. 
     A still further objective is to provide the ability to select coverings adapted for specific partial areas of the patient leaving other areas exposed for care and treatment. 
     The advantageous simplified structure of the thermal blanket make its production straight forward and economical. 
    
    
     These and other important objectives and advantages will become evident when the detailed description of the invention is read with reference to the below-summarized drawings, in which: 
     FIG. 1 is a side elevation view of a thermal blanket constructed in accordance with a first aspect of the invention, with the blanket in use, with associated thermal apparatus indicated schematically; 
     FIG. 2 is an enlarged top plan view of the thermal blanket opened flat; 
     FIG. 3 is an enlarged sectional view taken along  3 — 3  of FIG. 2; 
     FIG. 4 is a further enlarged sectional view taken along line  4 — 4  of FIG. 3; 
     FIG. 5 is a partial underside view of the thermal blanket; 
     FIG. 6 is a partial diagrammatic top plan view of a thermal blanket constructed in accordance with, a second aspect of the invention, with a partially constructed foot drape; 
     FIG. 7 is a partial projected view of a fully constructed thermal blanket of FIG. 6 in use, with the patient&#39;s feet illustrated by hidden lines underlying the foot drape; 
     FIG. 8 is a top plan view of a partially constructed thermal blanket in accordance with a third aspect of the invention, for thermally covering the pelvic area and lower extremities of a patient; 
     FIG. 9 is a partial projected view of a fully constructed thermal blanket of FIG. 8 in use; 
     FIG. 10 is a top plan view of a thermal blanket constructed in accordance with a fourth aspect of the present invention, for thermally covering the chest and upper extremities of a patient; and 
     FIG. 11 is a partial projected view of a fully constructed thermal blanket of FIG. 10 in use. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     When used herein, the term “thermal blanket” is intended to be interchangeable with, but not necessarily limited by, the term “airflow cover” used in our U.S. Pat. No. 4,572,188, which is incorporated herein in its entirety by reference. In this description, the term “thermal blanket” is meant to invoke a self-erecting, inflatable structure for delivering a thermally-controlled inflating medium to the interior of the structure created when the thermal blanket is inflated. The purpose of the thermal blanket is to efficiently administer a uniformly thermally-controlled bath of the inflating medium to a patient within the erected structure. 
     Our invention is illustrated as we intend for it to be used in a first aspect without a foot drape in FIG.  1 . In FIG. 1, a self-erecting, inflatable thermal blanket  10  has a head end  12 , a foot end  14  and two lateral edges, one indicated by  15 . An inflation inlet cuff  16  is connected to a heater/blower assembly  18  which provides a stream of heated air through a connecting hose  20 . When the heater/blower  18  is operated, the stream of heated air flows through the inflating hose  20  into the thermal blanket  10  through the inflation cuff  16 . When the blanket is inflated, it erects itself into a Quonset hut-like structure with a quilted upper surface  21 . As described below, a pattern of apertures on the undersurface of the blanket (not shown in FIG. 1) convectively delivers the inflating heated air into the interior space enclosed by the erected thermal blanket. 
     The contour of the inflatable portion of the thermal blanket  10  is varied at the head end  12  of the blanket to provide a non-inflated blanket recess  22  in the quilted upper surface  21 , which remains smooth and flat when the blanket is inflated and erected. Circulation of the heating air is accelerated through the thermal blanket by exhaust port openings in the upper surface, adjacent the lateral edges of the blanket. Two exhaust ports openings are indicated by reference numeral  23 . Further, a bib  24  made of an absorbent material is attached to the head end  12  of the thermal blanket in the vicinity of the non-inflated recess  22 . In fact, as shown in FIG. 1, the bib  24  includes a semi-circular tab  25  that extends into the recess  22 . 
     As illustrated in FIG. 1, the thermal blanket of the invention is inflated, erects itself into a bathing structure, and bathes a patient  26  with the thermally-controlled air used to inflate the structure. While the patient is being thermally bathed, the uninflated recess  22  permits observation of the patient&#39;s head, face, neck, and chest from almost any location with respect to the thermal blanket  10 . Thus, if the patient is placed on a gurney or a bed, the head of which is against a wall, a care giver such as a nurse, intern, resident, or doctor, can keep the patient&#39;s face under observation from the foot end  14  of the thermal blanket  20 . Respiration can be detected by the rise and fall of the bib and uninflated area, which rest directly on the patient&#39;s chest. Moreover, the bib  24  will provide an absorbent sink for stray, unconfined liquids in the area of the patient&#39;s head or at the head end  12  of the thermal blanket  10 . 
     FIG. 2 is a plan view of the thermal blanket  10  opened flat to show details of its structure. FIG. 2 illustrates the upper surface of the thermal blanket, that is the side that is visible in FIG.  1 . As seen, the upper surface consists of a parallel array of elongated tubes of which  30  and  32  are the lateralmost tubes,  34  is the center tube, and the tubes  38  are arrayed between one of the lateralmost tubes and the center tube. Each tube is separated from an adjacent tube by a discontinuous seam, one of which is indicated by  40 . The seam  40  separates the tube  32  and its nearest adjacent neighbor  38 . The discontinuous seam  40  is interrupted by passageways  42  communicating between the tubes. An interrupted seam separates every tube from one adjacent neighboring tube. The seams permit the thermal blanket, when inflated, to assume a tubular structure on the upper surface, while the ports  42  permit full circulation of the inflating medium throughout the array of tubes. The foot-end seam  45  is continuous. The tubes are inflated through the center tube  34  which transitions to a port  36 , through which the inflation cuff  16  is inserted. The edge seams  43  are discontinuous only at the exhaust port opening locations  23 . A seal can be made between the inflation port  36  and the inflation cuff  16  by any conventional means, for example, an o-ring, or even tape. When the inflating medium is introduced into the center tube  34 , it flows laterally from the center tube into all of the other tubes through the ports  42 . Near the head end  12 , a continuous seam  40  defines the forward end of all of the tubes, with the seam assuming a bell-curve shape. On the head end side of the seam  40 , the thermal blanket  10  is uninflatable. The bell-shaped seam  40  thus defines the uninflatable area  22  at the head end of the thermal blanket  10 , which is essentially coplanar with, or substantially parallel to, the underside of the blanket. As shown in FIG. 1, by virtue of its structural integration with the rest of the thermal blanket  10 , the non-inflated recess extends over the upper chest of the patient  26  when the blanket is inflated. However, since the recess  22  is uninflated, it provides a wide-angled viewing gap in the inflated contour of the upper surface  21 . The gap is filled by continuation of the underside of the blanket. It is also noted that the pattern of inflatable tubes can be replaced by other suitable patterns of communicating, inflatable chambers. 
     The tubes are preferred since they impart strength and shape to the erected bathing structure; other inflatable structures are contemplated, however. 
     The absorbent bib has an indent  44  cut into its outside edge, which permits the blanket to be drawn up to the chin of a patient and which provides absorbency laterally up the neck of the patient. The absorbent bib can consist of any absorbent material such as a single- or multi-ply tissue paper which is used to make paper towels. 
     Construction details of the thermal blanket  10  are illustrated in FIGS. 3 and 4. The thermal blanket  10  is assembled from a base sheet consisting of an underside layer  50  formed from flexible material capable of bonding to a layer  52  of heat-sealable plastic. For the layers  50  and  52 , we have used a stratum of absorbent tissue paper prelaminated with a layer of heat-sealable plastic. Material of such construction is commercially available in production rolls and is used to make painters&#39; drop cloths. The upper side of the thermal blanket consists of a sheet of plastic bonded to the plastic layer  52  by an interruptible heat-sealing process to form the interrupted seams, one of which is indicated by  54 , and the inflatable tubes, one indicated by  55 . As can be seen in FIG. 3, the interruption of the seam  54  forms a passageway  56  between adjacent tubes  55  and  57 . 
     The absorbent bib and tab are shown in FIG. 3 as a single material layer  60 / 58 . Alternatively, they may be formed from separate material sheets cut to the outlines illustrated in FIG.  2 . The absorbent material forming the bib and tab can be bonded to the upper plastic layer by heat process or by gluing. 
     The inventors also contemplate deletion of the bib and tab. In this instance, the thermal blanket would still have the viewing recess, which would be defined by the continuous seam at the head end and which would be filled with the forward portion of the base sheet. 
     Circulation of heated air through the blanket is enhanced by the exhaust port openings  23 , which open through the upper plastic sheet sheet, which is heat sealed to the base of the blanket. The openings  23  vent the heated inflating air out of the outermost tubes  30  and  32 , away from the underside of the blanket. Because air can circulate to, and through, the blanket edges, the inflating air in the outermost tubes is hotter than if the openings were absent. This results in hotter air being delivered through the underside apertures toward the edge of the blanket. We have measured the temperature distribution within the thermal blanket for inflating air which is heated to a medium temperature range and for inflating air which is heated to a high temperature range. The results are provided in Table I for a blanket consisting of  13  tubes. Measurements of the temperature of air exhausted through underside apertures were made on the underside of each tube on one side of the blanket. The tubes are numbered  1 - 6 , with  1  being the tube adjacent to the center tube, and tube  6  being the outermost tube adjacent on lateral edge of the blanket. Test apertures were made in the bottom of tube  6  only for the purposes of this test. As is evident, the distribution of temperature within the erected thermal blanket is more uniform when the exhaust port openings are provided. Further, provision of the exhaust ports also increases the average temperature within the erected structure of the blanket. Clearly, the provision of exhaust port openings at the lateral edges of the blanket delivers results which one would not expect when considering the operation of our thermal blanket with no exhaust port openings. 
     In our first preferred embodiment, the exhaust port openings are slits in the edge seams of our blanket. These slits vary in length from 1¾ to 2 inches. Each edge seam is discontinuous approximately at each corner of the blanket so that inflating air is vented away form the underside of the erected blanket. This keeps the relatively “colder” air at the blanket edges form mixing with the relatively “hotter” air exhausted into the structure through the underside apertures. The result is a “flatter” temperature profile of air within the blanket than without the vents, which raises the average temperature within the erected structure and makes the temperature distribution in the structure more uniform. 
     
       
         
               
               
               
             
               
               
               
               
               
             
           
               
                   
                 TABLE I 
               
             
             
               
                   
                   
               
               
                   
                 MEDIUM 
                 HIGH 
               
               
                   
                 TEMPERATURE 
                 TEMPERATURE 
               
               
                   
                 RANGE 
                 RANGE 
               
             
          
           
               
                   
                   
                 WITH 
                   
                 WITH 
               
               
                   
                 WITHOUT 
                 2″ 
                 WITHOUT 
                 2″ 
               
               
                   
                 EXHAUST 
                 EXHAUST 
                 EXHAUST 
                 EXHAUST 
               
               
                 TUBE NO. 
                 PORTS 
                 PORTS 
                 PORTS 
                 PORTS 
               
               
                   
               
               
                 center (inlet) 
                 113.3° F. 
                 114.1° F. 
                 121.3° F. 
                 121.3° F. 
               
               
                 tube 
               
               
                 Tube #1 
                 109.9° 
                 112.3° 
                 117.3° 
                 117.7° 
               
               
                 Tube #2 
                 105.3° 
                 109.8° 
                 113.4° 
                 115.0° 
               
               
                 Tube #3 
                 103.2° 
                 107.1° 
                 111.0° 
                 113.3° 
               
               
                 Tube #4 
                  99.9° 
                 104.3° 
                 101.4° 
                 108.6° 
               
               
                 Tube #5 
                  97.2° 
                 100.0° 
                  95.7° 
                 104.4° 
               
               
                 Tube #6 
                  85.2° 
                  95.8° 
                  89.6° 
                  99.4° 
               
               
                 (outermost) 
               
               
                 Average temp. 
                 103.8° 
                 106.7° 
                 108.4° 
                 112.5° 
               
               
                 under cover 
               
               
                   
               
             
          
         
       
     
     The thermal blanket of the invention is enabled to bathe a patient in the thermally-controlled inflating medium introduced into the upper side tubes by means of a plurality of apertures  62  shown in FIGS. 4 and 5. The apertures extend through the underside of the blanket, which includes the layers  50  and  52 . The apertures  62  are made in the footprints of the tubes of the blanket upper side according to a pattern which has been determined to deliver a very uniform thermal bath. In this regard, no apertures are provided through the underside into the lateral most tubes  30  and  32 , or into the center tube  34 . In addition, the apertures  62  are provided through the underside to the apertured tubes in a density which varies Resultantly, the clinical effect of the blanket is enhanced. Heating is better controlled, and more uniform, with greater comfort to the patient. inversely with the proximity of the tube to the center tube  34 . Thus, the hole density increases from the tube  38  a through the tube  38   d.  Even with the exhaust port openings, the temperature of the inflating medium exhibits a drop from the center to the lateral most tubes. The varying density of the apertures  62  tends to reduce this gradient further by forcing hotter air to the edges of the blanket. Thus, the thermal bath delivered to the patient is of a generally uniform temperature. The aperture density variation also equalizes the flow of inflating medium out of the apertures. As will be evident, the inflating pressure will be greatest at the center tube  34  and will tend to diminish toward the lateral edges of the thermal blanket. Therefore, fewer apertures are required for the tubes near the center tube  34  to deliver the same amount of air as the relatively greater number of apertures in the tubes at a greater distance from the center tube  34 . 
     The apertures comprise openings which can be of any appropriate shape. For example, we have produced blankets with elongated apertures, approximately ¼ inch in length. 
     Our invention is illustrated as we intend for it to be used in a second aspect including a foot drape in FIG.  7 . The foot end  14  of the thermal blanket  10  is modified to provide an uninflated drape forming section  70  formed by a rearward extension of the base sheet  50 / 52  and a noninflatable portion of the heat-sealable plastic bonded to the base sheet. The drape forming sheet  70  has sides  72  extending parallel to and rearwardly from the outside edge of the edge seams  43 , and a rear edge  74 . Optionally, the drape-forming sheet  70  further includes a pair of V-shaped cuts  76  in the rear corners thereof. The V-shaped cuts  76  are formed by converging cuts  78  and  80 , extending inwardly from one of the sides  72  and the rear edge  74 , respectively, to a point of intersection  82 . As shown in FIG. 7, the drape-forming section  70  may be formed into a foot drape  90  that includes a pair of side portions  92 , a rear portion  94  and an upper portion  96 . The drape  90  is so formed by joining the edges  78  and  80  of the V-shaped cuts  76  to form a pair of seams  98 . To form the seams  98 , the V-shaped cut edges  78  and  80  may be folded about respective lines  100  and  102  that parallel the edges  78  and  80 , as shown in FIG.  6 . The resulting respective folded surfaces  104  and  106  may then be fastened together by appropriate means such as heat sealing. Joining the surfaces  104  and  106  forms a crease  108  and transforms the two dimensional drape forming section  70  into the three dimensional drape  90 . 
     The resultant drape  90  is non-inflatable but erectable under the force of the heated medium circulating around the patient. The drape  90  thus traps and retains heat around the patient&#39;s feet to warm the feet. As shown in FIG. 7, the drape  90  also insulates the bare skin of the feet from excessive conductive heat from the inflating hose  70  in the event the hose is oriented in a position wherein it might otherwise come in contact with the feet. Patient warming and comfort is thus further enhanced. 
     Our invention is illustrated as we intend for it to be used in a third aspect as an inflatable lower body covering in FIGS. 8 and 9. This covering warms convectively by exhausting warm air onto a patient. The thermal covering in this case is similar in all respects to the covering shown in FIGS. 6 and 7, except that the covering may be shortened to cover only the pelvic area and lower extremities of the patient. Moreover, the head end of the covering may be modified to provide an open flat working area for the placement of instrumentation and to improve visualization of the care site, as shown in FIG.  9 . As in the case of the thermal coverings discussed above, the covering  110  of FIGS. 8 and 9 includes a head end  112 , a foot end  114 , a pair of lateral edges  115 , and an inflation inlet cuff  116  to which may be connected through a heater tube  20  to a heater/blower assembly such as the assembly  18  shown in FIG.  1 . As shown in FIG. 9, the covering  110  may be inflated to form a Quonset hut-like structure with a quilted upper surface  121 . Like the thermal covering  10 , a pattern of apertures on the undersurface of the blanket  110  convectively delivers the inflating heated air into the interior space enclosed by the erected thermal blanket. 
     Alternatively, the head end of the quilted upper surface  121  could extend directly from one edge  115  to the other edge  115  without the provision of a non-inflated blanket recess  122 , as shown in FIG.  8 . Further, an adhesive strip  124  made of an adhesive material may be attached to the head end  112  of the covering  110  and extend between the edges  110 . As shown in FIG. 8 a,  the adhesive strip  124  is mounted with its adhesive side oriented toward the base sheet, which includes an underside layer  150  formed from a flexible material capable of bonding to a layer  152  of heat sealable plastic. The layers  150 / 152  are formed in the same manner as the layers  50 / 52  shown in FIG.  3  and described above. Mounted to the underside of the adhesive strip  124  is a backing strip  125 , which may be positioned partially between the adhesive strip  124  and the layer  152  to prevent inadvertent peel-off. 
     As shown in FIG. 9, the adhesive strip  124  may be adhered above the patient&#39;s pelvic and groin area to prevent the migration of air from inside the covering  110  to the care site. Moreover, the optional non-inflated recess  122  may be large and well-defined in order to improve visualization of, the operating field and provide sufficient working area for resting instruments or other items during the rendering of care to a patient  126 . 
     Like its counterpart covering  10 , the covering  110  includes a parallel array of elongated tubes of which  130  and  132  are the lateralmost tubes,  134  is the center tube, and the tubes  138  are arrayed between one of the lateralmost tubes and the center tube. The thermal covering  110  further includes a non-inflated yet erectable foot drape for retaining a thermal medium around a patient&#39;s feet. As in the covering shown in FIG. 6, the covering  110  is provided with a non-inflated drape forming section  170  extending rearwardly from the foot end  114 . The covering  170  includes a pair of sides  172  and a rear edge  174 . Moreover, the drape forming sheet  170  includes a pair of V-shaped cuts  176  in the rear corner thereof. As shown in FIG. 9, the drape forming section  170  may be formed into an erectable foot drape  190  that includes a pair of side portions  192 , a rear portion  194 , and an upper portion  196 . As in the covering  10 , the drape  190  of the, covering  110  is formed by joining the edges of the V-shaped cuts  176  to form a pair of seams  198 . 
     As with the longer full-body thermal blanket of FIGS. 1 and 2, the covering  110  may be provided without a foot drape as appropriate. In that case, it may be desirable to slideably mount a protective sleeve  200  over the heater tube  20  to prevent the tube from contacting the patient. 
     Advantageously, it will be observed that the lower body warming cover  110  maintains a thermal medium around the pelvic and groin area and lower extremities of the patient, while at the same time exposing the patient&#39;s torso and head as may be necessary for the provision of medical care and treatment to those areas. 
     Alternatively, or in combination with the lower body thermal covering  110 , an upper body thermal covering  210  could be provided as shown in FIGS. 10 and 11. The upper body thermal covering  210  is structurally and functionally similar in most respects to the thermal coverings  10  and  110  discussed above. Thus, the thermal covering  210  includes a head end  212 , a foot end  214 , a pair of lateral edges  215 , and an inflation inlet cuff  216  which may be connected through a heater tube  20  to an external heater/blower assembly such as the assembly  18  shown in FIG.  1 . The thermal covering  210  further includes a quilted upper surface  22 , which may have non-inflated recess  222  located at the foot end of the covering, as shown in FIG.  11 . Thus, with the upper torso and arms of the patient being thermally bathed, the uninflated recess  222  permits observation of the patient&#39;s middle torso from almost any location with respect to the thermal covering  210 . 
     Alternatively, as shown in FIG. 10, the quilted upper surface  221  could extend across the entire expanse of the covering between the edges  215  such that no uninflated recess  222  is formed. It is preferable in most cases, however, to provide a recess  223  in the quilted upper surface  221  and the foot end  214  of the covering  210  to accommodate the curvature of the patient&#39;s torso, as shown in FIG.  11 . 
     There may be additionally provided an adhesive strip  224  mounted to the foot end  214  of the covering  210 . As shown in FIG. 10 a,  the adhesive strip  224  is mounted with the adhesive side facing the base sheet, which includes an underside layer  250  formed from a flexible material capable of bonding to a layer  252  of heat sealable plastic. The layers  250 / 252  are formed in the same manner as the layers  50 / 52  shown in FIG.  3  and described above. Mounted to the underside of the adhesive strip  224  is a backing strip  225 , which may be positioned partially between the adhesive strip  224  and the layer  252  to prevent inadvertent peel-off. As shown in FIG. 11, the adhesive strip  224  may be adhered to the patient&#39;s torso to prevent the migration of air toward the care site. 
     The covering  210  further includes an array of elongated tubes of which  230  and  232  are the lateral most tubes,  234  is the center tube and the tubes  238  are arrayed between one of the lateral most tubes and center tube. In addition, the thermal covering  210  includes a cutout area  240  centrally positioned at the head end  212  of the covering. The cutout  240  is formed by truncating the lateralmost tube  230  and an adjacent tube  238 . The recess  240  permits observation of the patient&#39;s head and neck from almost any location with respect to the thermal blanket  210 . It also assists in thermally covering the patient&#39;s shoulders and arms without covering the patient&#39;s face. As shown in FIGS. 10 and 11, the bottom layer  250 / 252  of the covering  210  may extend slightly beyond lateral edges  215  or the head end  212 , or it may be coextensive therewith. 
     As shown in FIG. 11, the thermal covering  210  is positioned over the patient&#39;s upper torso and arms so as to thermally control those areas while leaving the patient&#39;s lower torso exposed for the provision of care. As indicated, the thermal covering  210  may be used alone or in combination with the thermal covering  110  depending on the location of the care site. Thus, various selected portions of the patient may be selectively warmed with the illustrated thermal coverings while care and treatment may be rendered to other areas. In addition, a plastic head drape  260  may be adhesively mounted to the covering  210  over the patient&#39;s chest, and adjacent the head end  230 . The plastic head drape  260  is placed over the patient&#39;s head and one or more vents  270  may be provided to direct warmed air to the head area. 
     In a preferred method of operation, one or both of the coverings  110  and  210  may be selectively employed on a patient to warm selected portions of the patient while permitting other portions to remain exposed for treatment. In utilizing the coverings  110  and  210 , either alone or in combination, the covering  110  or  210  is first placed over the patient. The adhesive backing  125  or  225  is removed from the adhesive strip  124  or  224  and the adhesive strip is adhered to the patient to prevent the migration of air toward the care site. The hose  20  is then attached to the covering, an appropriate temperature is selected on the heater unit  18  and the unit  18  is activated. For the covering  110 , the protective heater tube  200  cover may also be used when the cover does not include a foot drape. For the covering  210 , the head drape  260  may,be adhered to the quilted portion  221  over the patient&#39;s chest and draped over the patient&#39;s head. As a final measure, a conventional blanket may be placed over the covering  110  or  210 . During operation, the patient&#39;s temperature should be monitored regularly and the air temperature setting of the heater unit  18  adjusted accordingly. 
     Many modifications and variations of our invention will be evident to those skilled in the art. For example, thermal coverings for additional selected patient areas could be implemented depending on the location of the care site and the need for thermally maintaining other areas. It is understood that such variations may deviate from specific teachings of this description without departing from the essence of the invention, which is expressed in the following claims.