Patent Publication Number: US-2022218359-A1

Title: Windlass tourniquet

Description:
This application claims the benefit of U.S. provisional patent application Ser. No. 62/845,051 filed on May 8, 2019, which is incorporated by reference herein in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to the field of tourniquets. 
     BACKGROUND OF THE INVENTION 
     Uncontrolled hemorrhage from trauma remains a major cause of death, both on the battlefield and in civilian situations. Untreated, extreme bleeding as in the case of arterial bleeding can cause hypovolemic shock within just minutes. 
     Tourniquets are well-known devices used to stop blood loss from trauma. When properly deployed, they provide life-saving support in emergency situations when an injured victim is alone or cannot reach immediate medical attention. A standard tourniquet is a tightly tied or wound band applied around an injured limb in an attempt to increase pressure around the limb, above the injury and stop severe bleeding or uncontrolled hemorrhaging. Rapid application of a tourniquet above the site of injury is paramount to effective hemorrhage control, as is rapid incremental release of a tourniquet once medical assistance is available to provide next-step trauma management. 
     Many known tourniquets are of the “windlass” type. Such tourniquets typically include a strap threaded through a windlass handle and coupled to a tourniquet base. In order to tighten the tourniquet around the limb, the strap is threaded through a buckle and the windlass handle is twisted creating a knot between the windlass and the base and causing the strap to constrict circumferentially about the limb. It is important to apply and maintain sufficient pressure to the limb to occlude blood flow until the tourniquet is removed. 
     A drawback to some of these known tourniquets is that sometimes the knot created in the compression strap as the tourniquet handle is twisted becomes too bulky and the windlass tends to fall to one side, limiting the ability to further turn and create additional pressure. If the knot becomes too bulky, it may be difficult for the user to apply sufficient torque. 
     Even when the user is able to apply sufficient pressure, most windlass tourniquets experience pressure loss or creep of up to 25% during the first five minutes after the tourniquet is applied. 
     Accordingly, there is a need for a windlass tourniquet that facilitates the application of circumferential pressure and that compensates for natural pressure creep that occurs within minutes of tourniquet application. 
     SUMMARY OF THE INVENTION 
     In accordance with an embodiment of the invention, a tourniquet having a base including at least first and second sections and having a cap attached to one of the first and second sections is provided. A compression strap is attached to the base and extends across the base wherein a portion of the compression strap is sandwiched between the base and the cap. A windlass handle is provided and includes a strap aperture through which the compression strap is threaded through and stitched to itself by a stitch pattern so as to form a strap loop. A locking strap extends across and is attached to the cap. A handle stop engages the locking strap such that the handle stop and freely slides along the handle strap. A strap connector assembly is provided and includes a buckle frame and a self-cinching sliding arm transversely extending from a first side of the buckle frame to a second opposing side of the buckle frame, a sliding arm configured to slide along the buckle frame. The compression strap is threaded through said buckle frame, and a buckle connector is attached to the compression strap to engage the buckle frame. 
     In accordance with another embodiment of the invention, a tourniquet having a base including at least first and second sections and having a cap attached to one of the first and second sections is provided. A compression strap attached to said base and extends across the base wherein a portion of the compression strap is sandwiched between the base and the cap. A windlass handle is provided and includes a strap aperture through which compression strap is threaded and stitched to itself by a stitch pattern so as to form a strap loop. The stich pattern is centered along a width of the compression strap and has a widthwise dimension that is between ¼ to ½ of the width of the compression strap. A strap connector assembly is provided and includes a buckle frame and a self-cinching sliding arm transversely extending from a first side of the buckle frame to a second opposing side of the buckle frame, a sliding arm configured to slide along the buckle frame. The compression strap is threaded through said buckle frame, and a buckle connector is attached to the compression strap and configured to engage the buckle frame. 
     In accordance with an embodiment of the invention, a tourniquet having a base including at least first and second sections and having a cap attached to one of the first and second sections is provided. A compression strap is attached to the base and extends across the base wherein a portion of the compression strap is sandwiched between the base and the cap. A windlass handle is provided and includes a strap aperture through which the compression strap is threaded through and stitched to itself by a stitch pattern so as to form a strap loop. A locking strap extends across and is attached to the cap and is threaded through a handle stop which allows the handle stop to slide along the locking strap. A strap connector assembly is provided and includes a buckle frame and a self-cinching sliding arm transversely extending from a first side of the buckle frame to a second opposing side of the buckle frame, a sliding arm configured to slide along the buckle frame. The compression strap is threaded through said buckle frame, and a buckle connector is attached to the compression strap and configured to engage the buckle frame. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Some embodiments of the present invention are illustrated as an example in the accompanying drawings and are described in sufficient detail to enable those skilled in the art to practice the invention. It is to be understood that other embodiments may be utilized and that structural changes based on presently known structural and/or functional equivalents may be made without departing from the scope of invention. The above and other objects, advantage and features of the present invention will be more readily apparent when read in conjunction with the following drawings wherein: 
         FIG. 1  depicts a top view of a tourniquet in accordance with an embodiment of the invention. 
         FIG. 2  is an exploded view of a tourniquet in accordance with an embodiment of the invention showing a stitch pattern. 
         FIG. 3  illustrates a tourniquet in accordance with an embodiment of the invention applied to a limb in a first position. 
         FIG. 4  depicts the tourniquet of  FIG. 3  applying greater circumferential force. 
         FIG. 5  shows a handle stop for a tourniquet of the present invention. 
         FIG. 6A  shows a buckle frame in accordance with an embodiment of the invention. 
         FIG. 6B  shows a strap connection assembly in accordance with an embodiment of the invention. 
         FIG. 6C  illustrates a self-cinching sliding member in accordance with an embodiment of the invention. 
         FIG. 7  depicts a strap connection assembly and strap combination in accordance with an embodiment of the invention. 
         FIG. 8  shows a tourniquet in accordance with an embodiment of the invention. 
         FIG. 9  shows a tourniquet in accordance with yet another embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Now, referring to the  FIG. 1 , a tourniquet  101  according to the invention includes a constricting band or compression strap  110  attached to/engaged with a base  115 . Compression strap  110  preferably has a width of between about 1 inch and about 3 inches, and more preferably a width of between about 1 inch and about 2 inches. In an embodiment, compression strap  110  has a width of about 1.5 inches. Compression strap  115  has a length that, at a minimum, is sufficient to allow the strap to be wrapped around the limb of an average size adult male. 
     Base  115  is preferably wider than compression strap  110 . In accordance with an embodiment of the invention, base  115  has a width of at least 2 inches. 
     A first end of compression strap  110  is fixedly attached, e.g., stitched, to base  115  at an attachment point proximate to a first end of base  115 . Compression strap  110  extends across and parallel to the base  115  by a sufficient distance to, at a minimum, allow compression strap  110  to be wrapped around the limb of an average size adult male. 
     A tourniquet handle  125  is provided for tightening tourniquet  101 . In some embodiments, tourniquet handle  125  is a windlass. In the illustrated embodiments, tourniquet handle  125  is generally cylindrical and may include locking grooves  127  disposed proximate first and second handle ends. In other embodiments, tourniquet handle  125  may be free from locking grooves. 
     Tourniquet handle  125  further includes an aperture through which compression strap  110  is threaded. As illustrated in  FIG. 2 , compression strap  110  is stitched to itself by a stitch pattern  130  to form a strap loop  135  which engages tourniquet handle  125 . As tourniquet handle  125  is tightened, compression strap  110  accumulates and forms a twist or knot  135  ( FIG. 3 ) which creates circumferential pressure. However, when the twist  135  is too bulky, tourniquet handle  125  has a tendency to fall to one side, thereby limiting the ability to continue to turn and create further circumferential pressure. 
     The present inventors have determined that the stitch pattern  130  impacts the size of twist  135 . In keeping with the invention, stitch pattern  130  may be triangular where the triangle is generally centered along a width of compression strap  110  and the base of the triangle extends transversely along the width of compression strap  110  generally parallel to tourniquet handle  125  as illustrated in  FIG. 2 . In keeping with an aspect of the invention, stitch pattern  130  has a maximum widthwise dimension of between ¼ to ½ of the width of compression strap  110 . In some embodiments, stitch pattern  130  may include various stitch patterns generally centered along the width of compression strap  110  including diamond, T, I and V shaped patterns. These patterns are believed to create different size twists but each is believed to markedly reduce the tendency of tourniquet handle  125  to fall to one side when it is tightened thereby making it easier to turn the handle and apply additional circumferential pressure. 
     A cap  140  overlays a portion of compression strap  110  and is fixedly attached to base  125  such that compression strap  110  is sandwiched between cap  140  and base  125 . A handle stop  145  and a handle lock  150  are attached to cap  140  via locking strap  155  which is fixedly attached to cap  140  at first and second ends. Handle lock  150  is optional and may be omitted from all embodiments of the invention. 
     In accordance with an aspect of the invention, stop  145  and handle lock  150  are configured to slide freely along locking strap  155  between first and second ends. That is, both the lock  150  and the stop  145  are subject only to minimal friction forces exerted by locking strap  155  as they slide along locking strap  155 . Neither lock  150  nor stop  145  are provided with any attachment mechanism to grip locking strap  155 . As shown in  FIG. 5 , in one embodiment, handle stop  145  is a generally C-shaped member having a strap aperture  160 . Compression locking strap  155  passes through strap aperture  160 . Strap aperture  160  is sufficiently wide that at most only one of the upper boundary and the lower boundary of strap aperture  160  contact locking strap  155  at any given time thereby allowing handle stop  145  to freely slide. Lock  150  may comprise a ring, e.g., a triangle ring or a D-ring. Locking strap  155  passes through the ring opening thereby allowing lock  150  to freely slide. 
     In use, tourniquet handle  125  is twisted to generate a desired amount of torque and inserted into handle stop  145  to maintain the desired torque. Handle lock  150  may be engaged with one of the grooves formed proximate to an end of tourniquet handle  125  to lock tourniquet handle  125  in place. However, within about 5 minutes after tourniquet application, circumferential pressure loss of up to about 25% may occur due to weave stretch and settling. The present invention provides an advantage in that the user can increase pressure by up to about 25% without removing the tourniquet handle by sliding stop  145  and/or stop  150  up and away from twist  135 . Illustrating this principle,  FIG. 3  depicts tourniquet  101  secured in a first position where stop  145  is proximate to twist  135  and  FIG. 4  illustrates tourniquet  101  secured in a second position where stop  145  has been slid away from twist  125 . 
     In some embodiments, base  115  is substantially rigid and therefore maintains its integrity as tourniquet handle  125  is twisted. By substantially rigid, it is meant that base  125  is sufficiently rigid to avoid binding or crushing when tourniquet handle  125  is twisted while being flexible enough for use on a limb and facilitating tourniquet carriage and storage. In a particular embodiment, base  125  is made of a 2″×8½″ section of central webbing member, a 2″×8½″ of looped end Velcro® affixed to the underside of the central webbing member, and a 2″×3″ strip of upper webbing member affixed to the upper side of the central webbing member. The central webbing member section may be made of a 16 point heavy weight polypropylene material or its equivalent. The upper webbing member may be made of nylon scuba webbing or its equivalent but each can be made of any other suitable material. For example, upper webbing member may be made of a plastic material. A nonskid or non-slip fabric or any other suitable material may be substituted for the looped end Velcro®. 
     The separate sections can be joined or combined by sewing, bonding or by using any suitable means. In the present embodiment, the looped end Velcro® section and the central webbing member are sewn together. The looped end of Velcro® is positioned so the bottommost layer of loop is in contact with the limb when the tourniquet  101  is used. Looped end of Velcro® is used in this embodiment to increase friction between the tourniquet  101  and the limb and to provide padding between the central webbing member and the tissue of the limb. Looped end of Velcro® also helps protect the skin and soft tissue from pinching and bruising that can be associated with the use of the tourniquet  101 . Looped end of Velcro® also helps the user in applying tourniquet article  10  by holding the tourniquet in place and allowing the user to apply article  10  with one hand. 
     The upper webbing member may be attached to the upper facing side of the central webbing member about 2″ in distance from the end of the upper webbing member and positioned beneath the handle  125 . In some embodiments, nylon scuba webbing may be used for the upper webbing member to increase the rigidity of the base  125  and to minimize binding or crushing of base  115  when handle  125  is twisted or turned. In other embodiments, multiple sections of scuba webbing can be combined to form the upper webbing member, and this can further facilitate the needs of rigidity while still being flexible enough for use with a limb in addition to making tourniquet  101  easier to store and carry. The loop end Velcro® member, central webbing member and upper webbing member may each be constructed of scuba webbing and, each member of base  125  can be lengthened, shortened, narrowed or widened. Additional padding may also be added to base  125 , or individually to loop end Velcro member, central webbing member or upper webbing member. One or more adhesive strips may also be used to bond one or more of the members comprising base  125 . 
     In some embodiments, tourniquet  101  may include a strap connecting assembly  200  for releasably connecting compression strap  110  to itself. Strap connecting assembly  200  may include a slider buckle having a frame  210  with a self-cinching slide member  225  engaged with frame  210  and a buckle connector  220  attached to base  115  and configured to releasably engage frame  210 . As depicted in  FIG. 6 , frame  210  includes a first aperture  230  configured to engage buckle connector  220  and a second aperture  235 . Second aperture  235  is defined by first and second longitudinal sides  236  and  237  and first and second axial sides  238 . In accordance with an aspect of the invention, self-cinching slide member  225  comprises a cuff or bar that extends across the second aperture  235  is externally mounted to first and second axial sides  238 . Second aperture  235  is sized to minimize slippage and provide smooth strap take up. In accordance with an embodiment of the invention, second aperture  235  measures, for example, ¾″×1½″. 
     While described above is particular embodiment of base  125 , in keeping with the invention, base  125  may comprise other structures and materials and need not be substantially rigid. 
     Self-cinching slide member  225  includes a longitudinal center section  240  and first and second C-shaped end pieces  242 . The first and second axial sides  238  fit snuggly within the crescent of the C-shaped end pieces allowing the self-cinching sliding bar to slide along opening in the axial direction. In keeping with the invention, self-cinching slide member  225  includes a strip gripping vane  244  that extends longitudinally from and protrudes radially along self-cinching member  225 . 
     As shown in  FIG. 7 , compression strap  110  is looped over self-cinching slide member  225  including over strap gripping vane  244  such that by simply pulling compression strap  110 , the self-cinching slide member  225  slides along frame  210  until compression strap  110  is pinched between self-cinching slide member  225  and one of longitudinal sides  236  and  237 . While not being bound by theory, it is believed that strap gripping vane  244  reduces strap slippage while under tension at angles of 45 degrees or less by altering the path of travel of compression strap  110 . 
     In accordance with an aspect of the invention, buckle frame  210  and sliding member  225  are preferably comprised a material that is significantly more lubricious than metal yet strong enough to withstand forces normally encountered when using tourniquets. In some embodiments, buckle frame  210  and sliding member  225  comprises a glass fiber reinforced polyamide which can withstand pull tests of up to 300 lbs. 
     Strap connector  220  comprises a hook member  222  and a strap channel base member  224  as shown in  FIG. 8 . Hook member  222  comprises a cuff having an interior surface. Hook member  222  extends from a strap channel base member  224  which defines a strap engaging aperture not shown in  FIG. 8 . Strap channel base member  224  may have edges and includes a first substantially vertical side from which hook member  222  extends and a second side which is slightly curved. 
     In keeping with the invention, as illustrated in  FIG. 9 , compression strap  110  is threaded through buckle connector  220  and fixedly connected to base  125 . This allows buckle connector  220  to slide freely along compression strap  110  between the point where compression strap  110  is attached to base  115  and stitch pattern  130 . It is believed that allowing buckle connector  220  to freely slide creates a mechanical advantage of up to 2:1 which reduces torque and makes the tourniquet easier to use particularly for users with weak grip strength. 
     In a further embodiment to any of the embodiments discussed above, the strap connecting assembly  220  may be substituted for strap connecting assemblies described in U.S. Patent Publication No. 20110307004 A1 or 2018175953 A1 or for any similar such assembly. In addition, any windlass handle having a central aperture may be substituted for windlass handle  125 . 
     Although particular materials have been identified for particular components and structural elements, one of ordinary skill in the art will appreciate that other materials may be substituted without departing from the scope of the invention. In at least one embodiment, slider buckle, the slide member and the buckle connector may comprise metal or plastic. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the root terms “include” and/or “have”, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     The corresponding structures, materials, acts, and equivalents of all means plus function elements in the claims below are intended to include any structure, or material, for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. 
     [As used above “substantially,” “generally,” and other words of degree are relative modifiers intended to indicate permissible variation from the characteristic so modified. It is not intended to be limited to the absolute value or characteristic which it modifies but rather possessing more of the physical or functional characteristic than its opposite, and preferably, approaching or approximating such a physical or functional characteristic. 
     [0089] Those skilled in the art will appreciate that various adaptations and modifications of the embodiments described above can be configured without departing from the scope and spirit of the invention. Therefore, it is to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described herein.