Abstract:
A method of performing cardiac surgery on a patient&#39;s heart, including covering a patient with an inflatable blanket for a forced air convection system, the inflatable blanket having at least one separable seal line within the blanket. The separable seal line may be separated to form a slit. A patient&#39;s femoral artery is accessed through the slit, and an elongate medical instrument is passed through the slit, and through the femoral artery toward the patient&#39;s heart. Cardiac surgery is performed with the elongate medical instrument, and the elongate medical instrument is withdrawn from the femoral artery through the slit.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a division of application Ser. No. 10/322,388, filed Dec. 19, 2002, which claims the benefit of Provisional Application Ser. No. 60/348,671, filed Jan. 17, 2002. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The invention relates to inflatable blankets for use with patients.  
         [0004]     2. Description of the Related Art  
         [0005]     Certain heart surgeries such as angioplasty involve inserting a catheter or other elongate medical instrument into the femoral artery of a patient&#39;s thigh, and passing the elongate medical instrument through the blood vessels to the heart.  
         [0006]     Excessive cooling of the patient is undesirable during surgery. Various patient warming systems have been proposed, including forced-air warming blankets that bathe a patient with warm air. However, known forced-air warming blankets for covering a patient&#39;s lower body interfere with access to the patient&#39;s thigh, necessary for performing cardiac surgery through the femoral artery.  
         [0007]     Forced-air warming blankets operate by use of a hose connected to the blanket for inflating the blanket with warm air. Positioning of the air delivery hose in forced-air warming blankets can interfere with performing cardiac surgery through the femoral artery.  
         [0008]     It also is desirable to provide a disposable forced-air warming blanket as a sterile unit. However, unwrapping and positioning of the blanket over a patient can compromise a sterile field established around a patient.  
         [0009]     Additionally, the air delivery hose for inflating a forced-air warming blanket is not likely to be sterile. Connecting and operating an unsterile air delivery hose with a forced-air warming blanket can thus also compromise the sterile field established around a patient.  
         [0010]     There thus remains a need in the art for improved forced-air warming blankets for use in cardiac surgery.  
       SUMMARY OF THE INVENTION  
       [0011]     In accordance with the present invention, cardiac surgery is performed on a patient utilizing an inflatable blanket for a forced-air convection system. The invention involves covering a patient with an inflatable blanket for a forced air convection system, the inflatable blanket having at least one separable seal line within the blanket, which separable seal line may be separated to form a slit; accessing a patient&#39;s leg (e.g. femoral) artery through the slit; passing an elongate medical instrument through the slit, and through the femoral artery toward the patient&#39;s heart; performing cardiac surgery with the elongate medical instrument; and withdrawing the elongate medical instrument from the femoral artery through the slit.  
         [0012]     According to one embodiment, the inflatable blanket comprises an upper sheet of material; a lower sheet of material, at least a portion of which is air-permeable; wherein said upper sheet and said lower sheet are sealed together around peripheral edges thereof to form an inflatable blanket having an upper end, a lower end for positioning near feet of a patient when said blanket is in use, and two sides which may be, e.g. substantially parallel, with an inflatable cavity between the upper and lower sheets, an inflation port located at the lower end of the inflatable blanket connecting said inflatable cavity with the atmosphere and through which air may be introduced to said inflatable cavity to inflate said blanket; and wherein said upper sheet and said lower sheet are further sealed together along at least two separable seal lines, such that when at least one of said separable seal lines is separated to form a slit, access through the blanket is provided through said slit to a desired area of the patient on whom said blanket is being utilized, wherein said separable seal lines are located in an upper half of said blanket opposite said lower end, said separable seal lines are spaced away from and do not intersect said upper end, said sides and said lower end, and said separable seal lines are two sides which may be, e.g. substantially parallel with each other and with said sides of said blanket.  
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0013]      FIG. 1  shows a plan view of an inflatable blanket for a forced air convection system according to one embodiment of the invention;  
         [0014]      FIG. 1A  shows a partial section through the embodiment of the inflatable blanket shown in  FIG. 1 .  
         [0015]      FIG. 2  shows a three-quarter view, partially cut-away, of an inflatable blanket for a forced air convection system according to a second embodiment of the invention;  
         [0016]      FIG. 3  shows separable seal lines for use with an embodiment of the invention;  
         [0017]      FIG. 4  shows a three-quarter view, partially cut-away, of an inflatable blanket for a forced air convection system according to a third embodiment of the invention;  
         [0018]      FIG. 5 a  three-quarter view, partially cut-away, of a shield for use with the embodiment of the invention shown in  FIG. 4 ;  
         [0019]      FIG. 6  shows a three-quarter view, partially cut-away, of an inflatable blanket for a forced air convection system according to a fourth embodiment of the invention;  
         [0020]      FIG. 7  shows an inflatable blanket for a forced air convection system according to a fifth embodiment of the invention; and  
         [0021]      FIG. 8  shows an inflatable blanket for a forced air convection system according to a sixth embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0022]     In one embodiment, the invention provides an inflatable blanket for a forced air convection system comprising an upper and a lower sheet of material, with at least a portion of the lower sheet being air-permeable. The upper and lower sheets are sealed together around their peripheral edges to form an inflatable blanket, preferably having a generally rectangular shape with an upper end, a lower end for positioning near the feet of a patient when the blanket is in use, and two sides which may be, e.g. substantially parallel, with an inflatable cavity between the upper and lower sheets. An inflation port may be located at the lower end of the inflatable blanket to connect the inflatable cavity with the atmosphere and through which an inflation medium may be introduced to the inflatable cavity to inflate the blanket. The upper and lower sheets are further sealed together along at least two separable seal lines, such that when the separable seal lines are separated to form slits, access to desired areas of the patient on whom the blanket is being utilized is provided through the blanket through the slits. The slits of the seal lines are located in an upper half of the blanket opposite the lower end, the slits are spaced away from and do not intersect the upper end, the sides and the lower end, and the slits are substantially parallel with each other and with the sides of the blanket.  
         [0023]     In another embodiment, the invention provides a method of using the inflatable blanket described above which includes the steps of tearing open a pouch containing the blanket in a folded condition, removing the blanket from the pouch, placing the blanket in the folded condition over a patient, opening the blanket down and out, attaching a hose of the blanket to a source of an inflation medium, extending a shield over the hose, and inflating the blanket.  
         [0024]     In  FIG. 1  is shown an inflatable blanket  2  for a forced air convection system according to a first embodiment of the invention. The inflatable blanket  2  includes an upper sheet  4  and a lower sheet (not shown in  FIG. 1 ). Inflatable blanket  2  may be made of, e.g. a polymer such as a plastic, a fabric, or a composite fiber.  
         [0025]     Inflatable blanket  2  has a generally rectangular shape with an upper end  16 , a lower end  18  for positioning near, e.g. feet of a patient when the blanket  2  is in use, and two sides  24 ,  26  which may be, e.g. substantially parallel, with an inflatable cavity between the upper sheet  4  and the lower sheet.  
         [0026]     The upper sheet  4  and the lower sheet are sealed together around peripheral edges  14  to form the inflatable blanket  2 . Peripheral edges  14  may be sealed by, e.g. plastic welding, heat welding, or by applying an adhesive to one or both peripheral edges  14  and matching peripheral edges  14  together. The adhesive may be e.g. a two-part adhesive, such as an epoxy.  
         [0027]     Upper sheet  4  and the lower sheet may also be sealed together along at least two separable seal lines  36 ,  38  in a substantially similar manner. Separable seal lines  36 ,  38  may be formed by, e.g. a line of perforations, or an adhesive or heat or plastic weld between upper sheet  4  and the lower sheet, or within upper sheet  4  and the lower sheet, which is weak in, e.g. shear or tension relative to the local shear or tensile strength of a parent material of inflatable blanket  2 .  
         [0028]     Upper sheet  4  and the lower sheet may also be sealed together at spot welds  37  and weld lines  39  in a manner substantially similar to that of peripheral edges  14 . Weld lines  39  may, e.g. direct an inflation medium flow entering the blanket around the area of a patient&#39;s feet, thus limiting the inflation medium flow around the patient&#39;s feet. In a preferred embodiment, weld lines  39  end approximately 2 inches or 5.08 centimeters from peripheral edge  14 , leaving a gap through which a limited amount of an inflation medium may flow into the area of the blanket  2  proximate to the patient&#39;s feet.  
         [0029]     Inflatable blanket  2  further includes an inflation port  30  communicating with an inflation cavity. Weld lines  39  may, e.g. form a central air passageway within the inflatable cavity communicating with the inflation port.  
         [0030]     In  FIG. 1A  is shown a partial section  1 A- 1 A through a spot weld  37  of inflatable blanket  2 . In  FIG. 1A  upper sheet  4  and lower sheet  8  are sealed together at spot welds  37 . Lower sheet  8  may be perforated with perforations  12 .  
         [0031]     In  FIG. 2  is shown an inflatable blanket  102  for a forced air convection system according to a second embodiment of the invention. The inflatable blanket  102  includes an upper sheet  104  of a first material  106  and a lower sheet  108  of second material  110 . First and second materials  106 ,  108  may be, e.g. a polymer such as a plastic, a fabric, or a composite fiber. First and second materials  106 ,  108  may be the same material, or different materials.  
         [0032]     The upper sheet  104  and lower sheet  108  are sealed together around peripheral edges  114  to form the inflatable blanket  102 . Upper and lower sheets  104 ,  108  may be sealed by, e.g. plastic welding, heat welding, or by applying an adhesive to one or both peripheral edges  114  and matching peripheral edges  114  together. The adhesive may be e.g. a two-part adhesive, such as an epoxy. Upper sheet  104  and lower sheet  108  may also be sealed together along at least two separable seal lines  136 ,  138  in a substantially similar manner. Separable seal lines  136 ,  138  may be formed by, e.g. a line of perforations, or an adhesive or heat or plastic weld between upper and lower sheets  104 ,  108 , or within upper and lower sheets  104 ,  108 , which is weak in, e.g. shear or tension relative to the local shear or tensile strength of parent first or second materials  106 ,  108 .  
         [0033]     In the illustrated embodiment, inflatable blanket  102  has a generally rectangular shape with an upper end  116 , a lower end  118  for positioning near, e.g. feet  120  of a patient  122  when the blanket  102  is in use, and two sides  124 ,  126  which may be, e.g. substantially parallel, with an inflatable cavity  128  between the upper and lower sheets  104 ,  108 .  
         [0034]     An inflation port  130  located at the lower end  118  of the inflatable blanket  102  connects the inflatable cavity  128  with the atmosphere  132  and through which an inflation medium  134  may be introduced to the inflatable cavity  128  to inflate the blanket  102 . At least a portion of lower sheet  108  is air-permeable though perforations  112 . Perforations  112  may be, e.g., small holes or slits. The size or aggregate flow area of perforations  112  may be, e.g., matched to a rate of flow of inflation medium  134  into blanket  102  such that blanket  102  remains inflated during use, but does not burst.  
         [0035]     Inflation medium  134  may be, e.g. air, such as a combination of oxygen, water vapor, nitrogen, and trace elements like argon, or an inert gas such as N 2 . Inflation medium  134  may be introduced to inflatable cavity  128  by, e.g. pumping inflation medium  134  into inflatable cavity  128 , applying a pressure differential across inflatable cavity  128  between inflation port  130  and perforations  112  or any alternative egress, or by evacuating some portion of the surroundings of blanket  102 . In a preferred embodiment, inflation medium  134  may be heated. Heat may also, e.g. provide at least some of the pressure differential across inflatable cavity  128  described above.  
         [0036]     As shown in  FIG. 3 , separable seal lines  236 ,  238  may be separated to form slits  240 ,  242  without substantially deflating blanket  202 . Access to desired areas of the patient on whom the blanket  202  is being utilized is provided through the slits  240 ,  242 . Slits  240 ,  242  may, e.g. offer access to the thighs of a patient, after, e.g. a vein harvesting operation. Slits  240 ,  242  are located in an upper half  244  of the blanket  202  opposite the lower end  218 , the slits  240 ,  242  are spaced away from and do not intersect the upper end  216 , the sides  224 ,  226  or the lower end  218 . Slits  240 ,  242  may be, e.g. substantially parallel with each other and with the sides  224 ,  226  of the blanket  202 . In a preferred embodiment, slits  240 ,  242  may be tear-open slits.  
         [0037]     In a third embodiment of inflatable blanket  302  shown in  FIG. 4 , a hose  344  with a proximate end  346  may connect the inflation port  330  with a distal end  348  located outside a sterile field  350 . Hose  344  may be, e.g. an air supply hose or a plastic tube. Sterile field  350  may be, e.g. an area around patient  322  in which an effort has been made to substantially dispose of, remove, or otherwise render harmless bacteria, organisms, viruses, vileness &amp; corruption, or other entities, living or non-living, that may be potentially detrimental to the health or recovery of patient  322 .  
         [0038]     Inflatable blanket  302  may be inflated through the distal end  348  so that the sterile field  350  is not compromised by the incoming inflation medium  334 . Thus, inflation medium  334  may enter hose  344  at distal end  348  and travel through hose  344  to proximate end  344  without substantially contacting or contaminating sterile field  350 . In one embodiment, the distal end may have a nozzle  352 . Nozzle  352  may be, e.g. a connector of the ‘quick disconnect’ variety. Nozzle  352  may further comprise a restriction for, e.g. controlling or limiting the rate of flow of inflation medium  334 . In a preferred embodiment, shown in  FIG. 5 , a shield  354  is placed over the nozzle  352  to extend the sterile field  350   a  over the hose  344 . Shield  354  may be, e.g. a tubular or semi-tubular sheath made of, e.g. plastic, rubber, a composite, or a fiber mat.  
         [0039]     In a fourth embodiment, shown in  FIG. 6 , inflatable blanket  402  has a throttle  456  to reduce a flow  458  of inflation medium  434  proximate to the feet  420  of the patient  422 . If, e.g., inflation medium has the effect of raising or lowering a temperature of feet  420 , it may be desirable to limit the flow of  458  of inflation medium  434  locally to feet  420 , while allowing inflation medium  434  to circulate substantially freely in the remainder of inflatable blanket  402 , in order to maintain a temperature of feet  420  at a comfortable level. Throttle  456  may thus reduce the ‘loft’ in the area of blanket  402  proximate to feet  420  relative to that of the remainder of blanket  402 . Throttle  456  may be, e.g. a baffle, a restriction, or a constriction, such as a weld line or a seal area. In a preferred embodiment, throttle  456  ends approximately 2 inches or 5.08 centimeters from peripheral edge  414 . Throttle  456  may further be, e.g. a controllable restriction, such that a range of rates of flow  458  of inflation medium  434  may be applied locally to feet  420 .  
         [0040]     In a fifth embodiment, shown in  FIG. 7 , inflatable blanket  502  is contained in a pouch  558  arranged around the blanket  502  before the inflation medium has been introduced to the blanket  502 . Inflatable blanket  502  can thus be presented into a sterile field before pouch  558  is opened. In a preferred embodiment, pouch  558  has a tear-open opening  560 . Tear-open opening  560  may be produced by, e.g. a line of perforations, or an adhesive or heat or plastic weld between the sides of pouch  558  which is weak in, e.g. shear or tension relative to the local shear or tensile strength of a parent material of pouch  558 .  
         [0041]     In a sixth embodiment, shown in  FIG. 8 , inflatable blanket  602  has a fold  662  which allows the blanket  602  to open and allows placement over an abdomen  664  of the patient  622  before the inflation medium has been introduced to the blanket  602 . In a preferred embodiment, blanket  602  opens downward without contaminating sterile field  650 .  
         [0042]     The inflatable blanket  602  may be used by tearing open pouch  558  containing the blanket in a folded condition, removing blanket  602  from the pouch  658 , placing blanket  602  in the folded condition over a patient  622 , opening blanket  602  down and out, and inflating the blanket  602 .  
         [0043]     While the invention has been described in detail above, the invention is not intended to be limited to the specific embodiments as described. It is evident that those skilled in the art may now make numerous uses and modifications of and departures from the specific embodiments described herein without departing from the inventive concepts.