Patent Publication Number: US-2017354422-A1

Title: Emergency arterial tourniquet device and associated methods of use and manufacture

Description:
CROSS REFERENCES 
     This application claims priority from U.S. Provisional Patent Application No. 61/444,487 filed Feb. 18, 2011 incorporated herein in its entirety by this reference, via co-pending U.S. Utility Application Ser. No. 13/397,166 filed on Feb. 15, 2012, in the name of the same inventor, the entirety of which is also incorporated herein by this reference. 
    
    
     TECHNICAL FIELD 
     The present technology is related to medical devices. In particular, the present disclosure is related to arterial tourniquet devices and associated methods of use and manufacture. 
     BACKGROUND 
     Tourniquets are devices that can control venous and arterial circulation to extremities. In operation, tourniquets apply pressure circumferentially upon skin and underlying tissues of a limb, and in addition apply direct pressure to the target vein or artery. The pressure, circumferential and targeted, transfers to the walls of vessels, causing them to compress, constrict, and become temporarily occluded. To avoid further injury to the limb, the tourniquet pressure should be sufficient to stop blood flow, but should not be strong enough to damage tissue, nerves, and/or blood vessels. The tourniquet should be easily tightenable and loosenable both. 
     In general, tourniquets are categorized as either surgical tourniquets or emergency tourniquets. Tourniquets used during surgery allow surgeons to work on limbs in a bloodless setting, and accordingly include specialized instruments to gauge the correct pressures for specific applications. Surgical tourniquets, for example, are generally pneumatic devices that include pressure gauges, electrical inflation mechanisms, sensors, and/or outer devices suitable for hospital settings. In contrast, tourniquets used in emergency settings are used to prevent severe blood loss prior to a victim reaching a state of shock and prior to hospital care. Thus, emergency tourniquets are configured to facilitate easy and quick application to stop blood flow from a limb prior to more intensive hospital care. 
     Emergency tourniquets are especially advantageous in military settings, where pre-hospital care is critical. During combat, for example, explosions (e.g., improvised explosive devices) and gun fire can result in traumatic injuries that require immediate occlusion of blood flow. Additionally, formal medical care may not be readily available in combat situations. Thus, emergency tourniquets are often stored on military personnel and/or in military vehicles to ensure tourniquets are available when traumatic bleeding injuries occur. However, military personnel generally carry heavy gear (e.g., weaponry, backpacks, water containers, etc.) when in combat, making the additional storage of a tourniquet inconvenient. Additionally, tourniquets stored in military vehicles may be difficult to access after an injury causing event because the vehicle may be difficult to reach and/or retrieval of the tourniquet may be impractical due to damage to the vehicle. 
     In addition, emergency tourniquets are necessary for emergency workers and first responders such as firemen, EMTs, law enforcement personnel, private contractors, and anyone working or playing in a dangerous situation, such as saw-mills, foot patrols, isolated work places and so on. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention specifically addresses and alleviates the above mentioned deficiencies, more specifically, the present invention is directed to a simple, fast and effective arterial tourniquet device that can be quickly deployed and used in the field, including by the wounded soldier if need be. The arterial tourniquet devices and methods of use according to the present invention are configured in embodiments that include and comprise, for example, a strap having a proximal end portion and a distal end portion, a buckle assembly connected to the proximal end portion, and a pulley assembly movably coupled to the strap. The two pulley assemblies combine to form a single “true pulley” offering mechanical advantage of 2:1 on force applied by a user. In addition, the two pulley assemblies may have a tray/support part which is forced into the limb at a specific point and thus allow a user to rotate the tourniquet device about the limb, line up one pulley assembly over an artery or vein in a calf, thigh, arm, etc, and then tighten it to directly pressure the blood vessel and occlude it. Tourniquet devices configured in accordance with the technology can be easily applied because the pulley assemblies can reduce the force a user must exert on the tourniquet devices to constrict or occlude blood flow, in fact, halving the pressure to be applied. Additionally, tourniquet devices disclosed herein can also serve as functional, wearable items (e.g., a belt, integrated into clothing) such that the tourniquet devices are conveniently stored and readily accessible in emergencies and have multiple other field uses, including, e.g., gun straps, backpack straps, seat belts and as restraint devices, either on personnel or on vehicles, equipment, installations, buildings and so on. 
     Accordingly, in a first aspect, the present invention provides a tourniquet device comprising a strap having a proximal end portion and a distal end portion, a buckle assembly connected to the proximal end portion of the strap, and a pulley assembly slidably coupled to the strap and movable between the proximal end portion and the distal end portion, the pulley assembly having a support member and a pulley member rotatably coupled to the support member. In a preferred embodiment, the strap has a width sufficient to apply pressure to constrict blood flow, while preventing constricting blood flow to the point of injury or amputation. In another preferred embodiment, one pulley member has a support which is actually forced into the encircled limb when pressure is applied, so as to directly pressure a desired spot, i.e. a blood vessel. 
     In a further aspect, the buckle assembly a frame for connecting the end portion of the strap, and in a preferred embodiment, can include a second pulley member coupled to the frame to bias the buckle assembly away from the injured limb. 
     In another aspect, the size of the plurality of openings is proportional to the weight of the flexible material. 
     In yet a further aspect, the pulley mechanism includes a clamping member to allow free movement of the strap in one direction and restricted movement in the opposite direction. 
     In a further aspect, the pulley attachment mechanism allows for incremental loosening and tightening of the tourniquet device and selective reattachment to the distal end of the strap as pressure in increased or decreased. 
     In another aspect of the present invention, a method of applying a tournaquet devices according to the present invention is provided, comprising the steps of encircling a limb above the point of blood loss with a tourniquet device comprising: 
     a strap having a proximal end portion and a distal end portion; 
     a buckle assembly connected to the proximal end portion of the strap; and 
     a pulley assembly slidably coupled to the strap and movable between the proximal end portion and the distal end portion, the pulley assembly having a support member and a pulley member rotatably coupled to the support member; and looping the distal end portion of the strap through the buckle assembly to reverse directions, looping the distal end portion of the strap through the pulley member, applying sufficient pressure to constrict blood flow by pulling the distal end of the strap away from the pulley assembly to tension the strap, transferring circumferential pressure to the limb and direct pressure to any artery below the pulley support, and releasably securing the distal end portion to an attachment mechanism. 
     It is therefore on embodiment of the invention, in addition to those objectives and aspects mentioned previously, to provide a tourniquet device, for a primary use applying pressure to an artery in a patient&#39;s limb and a secondary use worn as a belt looped around a wearer&#39;s torso, the tourniquet device comprising: 
     a strap having a proximal end portion and a distal end portion; 
     a first buckle assembly connected to the proximal end portion of the strap; 
     a second pulley assembly slidably coupled to the strap and movable between the proximal end portion and the distal end portion, the second pulley assembly having first and second apertures passing therethrough, the second pulley assembly located at a distance from the first buckle assembly; 
     the second pulley assembly having a pulley assembly support and a first pulley member rotatably coupled to the pulley assembly support and biased away from the pulley assembly support; 
     the first buckle assembly having a frame for connection to the proximal end portion of the strap and forming an opening wherein at least one post extends across the opening; 
     the first buckle assembly further having a second pulley member rotatably coupled to the frame, the second pulley member rotating away from the frame; 
     the strap passing through the first and second apertures of the second pulley assembly and then about the second pulley of the first buckle assembly; 
     whereby a pulley having a two-to-one force multiplication is formed by the first and second pulleys and the strap passing between them; 
     and further whereby an opening is formed through which in a first such usage, such artery in such limb may extend and be encircled and in a second such usage such tourniquet device may be worn as a belt. 
     It is therefore another embodiment, aspect, objective, and advantage of the present invention to provide a tourniquet device, wherein the first pulley extends away from the pulley assembly support and the opening; whereby when tightened it exerts torque which forces the pulley assembly support into a part of the limb directly under the first pulley, and when the part of the limb directly under the first pulley is such artery, such artery is occluded. 
     It is therefore another embodiment, aspect, objective, and advantage of the present invention to provide a tourniquet device, wherein the second pulley member includes a pulley reinforcement support extending across the opening and provides support for the second pulley member. 
     It is therefore another embodiment, aspect, objective, and advantage of the present invention to provide a tourniquet device, wherein the pulley assembly support is configured to include at least one aperture for slidably attaching the pulley assembly to the strap. 
     It is therefore another embodiment, aspect, objective, and advantage of the present invention to provide a tourniquet device, wherein the pulley member includes a roller portion rotatably coupled to a hinged portion. 
     It is therefore another embodiment, aspect, objective, and advantage of the present invention to provide a tourniquet device, wherein the pulley member includes a clamping mechanism configured to allow the strap to pass substantially freely in one direction and substantially preventing the strap from passing in the opposite direction. 
     It is therefore another embodiment, aspect, objective, and advantage of the present invention to provide a tourniquet device, further comprising means for attaching for releasably securing the distal end portion of the strap to the tourniquet device. 
     It is therefore another embodiment, aspect, objective, and advantage of the present invention to provide a tourniquet device, wherein the means for attaching is configured to allow for incremental loosening or tightening of the tourniquet device and reattachment of the distal end to the strap at each incremental pressure decrease or increase as applied to such limb. 
     It is therefore another embodiment, aspect, objective, and advantage of the present invention to provide a tourniquet device, wherein the device is configured for wearing or storing in a form selected from a member of the group consisting of a belt, a backpack strap, integrated as part of a piece of clothing, and integrated as part of a vehicle. 
     It is therefore yet another embodiment, aspect, objective, and advantage of the present invention to provide a tourniquet device, wherein the device can function as a device selected from the group consisting of a suspensory device, restraint, and securing device for a splint. 
     It is therefore yet another embodiment, aspect, objective, and advantage of the present invention to provide a tourniquet device, further comprising: 
     hook-and-loop fabric on the strap, the hook-and-loop fabric having both hooks and loops at every part so that any part of the hook-and-loop fabric may attach to any other part. 
     It is therefore yet another embodiment, aspect, objective, and advantage of the present invention to provide a method of applying a tourniquet device to apply pressure to an artery in a limb, comprising the steps of: 
     encircling such limb above the point of blood loss with a tourniquet device comprising: 
     a strap having a proximal end portion and a distal end portion, 
     a buckle assembly connected to the proximal end portion of the strap; and 
     a pulley assembly slidably coupled to the strap and movable between the proximal end portion and the distal end portion, the pulley assembly having a pulley assembly support and a pulley member rotatably coupled to the pulley assembly support; 
     looping the distal end portion of the strap through the buckle assembly to reverse directions; 
     wherein the buckle assembly of step ii) further comprises a second pulley member rotatably coupled to a frame and wherein the looping of the distal end portion of the strap is through the second pulley member; 
     then looping the distal end portion of the strap through the first pulley member; whereby a pulley having a two-to-one force multiplication is formed by the first and second pulleys and the strap passing between them; 
     rotating the strap about such limb until the first pulley member is directly over such artery; 
     applying sufficient pressure to constrict blood flow through such artery by pulling the distal end of the strap away from the pulley assembly to tension the strap, transferring circumferential pressure to such limb and direct pressure to such artery; and 
     releasably securing the distal end portion to an means for attaching. 
     It is therefore yet another embodiment, aspect, objective, and advantage of the present invention to provide a tourniquet method, wherein the pressure applied to such limb and artery is incrementally reduced or increased by releasing the distal end portion from the means for attaching and resecuring the strap to the means for attaching at an incremental position equivalent to a reduction or increase in pressure to such limb. 
     It is therefore yet another embodiment, aspect, objective, and advantage of the present invention to provide a tourniquet method, wherein the means for attaching is hook-and-loop fabric on the strap, the hook-and-loop fabric having both hooks and loops at every part so that any part of the hook-and-loop fabric may attach to any other part. 
     While the tournaquet devices and methods will be described for the sake of grammatical fluidity with functional explanations, it is to be expressly understood that the claims, unless expressly formulated under 35 USC 112, or similar applicable law, are not to be construed as necessarily limited in any way by the construction of “means” or “steps” limitations, but are to be accorded the full scope of the meaning and equivalents of the definition provided by the claims under the judicial doctrine of equivalents, and in the case where the claims are expressly formulated under 35 USC 112 are to be accorded full statutory equivalents under 35 USC 112, or similar applicable law. The invention can be better visualized by turning now to the following drawings wherein like elements are referenced by like numerals. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a tourniquet device secured around a limb in accordance with embodiments of the new technology. 
         FIG. 2  is a front view of the tourniquet device shown in  FIG. 1  worn as a belt in accordance with the new technology. 
         FIGS. 3A and 3B  is an enlarged isometric view of a pulley assembly configured in accordance with embodiments of the new technology. 
         FIG. 4  is an enlarged top view of a buckle assembly configured in accordance with embodiments of the new technology. 
         FIG. 5  is an enlarged back view of a portion of the tourniquet device shown in  FIG. 1  in accordance with embodiments of the new technology. 
         FIG. 6A  is an isometric view of a buckle assembly configured in accordance with other embodiments of the new technology, and  FIG. 6B  is a top view of the buckle assembly shown in  FIG. 6A . 
         FIG. 7  is a side view of a tourniquet device configured in accordance with further embodiments of the new technology. 
         FIG. 8  is a side view of a simplified true pulley showing basic principles of mechanical engineering. This is PRIOR ART. 
     
    
    
     DETAILED DESCRIPTION 
     Glossary 
     There are 6 different categories of simple machines: the inclined plane, the wheel/axle, the lever, the true pulley, the screw and the wedge, which were long ago categorized and understood. This may be verified at such sources as: Sciencing.com: http://sciencing.com/list-five-types-pulleys-8673129.html, or at LIVE SCIENCE, http://wvvw.livescience.com/49106-simple-machines.html as well. This is not a new classification either, the ancient history of the simple machines may be verified at https://social-la-wiki.wikispaces.com/Greek+Inventions or https://prezi.com/awargsdp5tuu/the-history-of-single-machines/. Hero of Alexandria&#39;s work “Book On Raising Heavy Weights” illustrates pulleys in antiquity. 
     The pulley may be seen to have several key features: a rope used to apply tension (unlike a lever, inclined plane, etc), two pulleys which change the direction of the rope by 180 degrees TWICE, and so on. 
     The present invention teaches, among other features, a pulley used to tighten a tourniquet which cuts off arterial blood flow. The word “pulley” is used throughout the present application. However, it has two different meanings, and regrettably, the two meanings must BOTH be used for clarity, even in the claims. 
     FIRST USAGE OF “PULLEY”: technically, a simple wheel, with the axle mounted and a rope passing around 180 degrees of the circumference of the wheel is NOT a pulley, but rather a “sheave” or “block”. Nonetheless, the word pulley is the easiest description of a single wheel with a rope about it. A single such “pulley” in fact confers NO mechanical advantage: when the user pulls the rope by a displacement Y against force of X/2, the load on the other side of the single wheel/block/sheave/pulley also moves by the exact same increment: displacement Y due to the same force of X/2. However, the single sheave is nonetheless commonly called a “pulley” and for clarity will be called as such herein. If this is an issue during prosecution, the word “block” may be substituted at a later point in prosecution, being more technically correct but less useful for communication. 
     SECOND USAGE OF THE WORD PULLEY: The true pulley.  FIG. 8  illustrates a “true pulley” which offers 2:1 mechanical advantage. A single true pulley requires the use of “two pulleys”, meaning two blocks. It may be seen that when the user of a true pulley pulls the rope by the displacement of Y, with a force of X/2, the resultant displacement is only Y/2, however, the user&#39;s mechanical advantage exerts a force X (double the original force) on the load to be moved. 
     Tourniquets require a surprising amount of force to be effective. Under battlefield conditions, first aid conditions or other stress conditions it may be hard to exert such force. In particular, the force necessary to close an artery, which is normally well inside of the human body, can be quite high. The femoral artery for example sits against the large muscles of the human thigh. 
     Hook-and-loop fabric as used herein may refer to fabric in which one area has hooks and another part has loops, however, the type in which every part of the hook-and-loop fabric has both hooks and loops is preferred (Omni-tape® made by the original Velcro® company is an example of this type), as this type of fabric can stick to itself at any part to any part: it is no longer necessary to match a hooks only part to a loops only part. 
     End Glossary 
     The present technology is directed to tourniquet devices and associated methods of use and manufacture. A tourniquet device configured in accordance with several embodiments of the disclosure can include, for example, a strap having a proximal end portion and a distal end portion, a buckle assembly connected to the proximal end portion, and a pulley assembly movably coupled to the strap. In operation, the strap can be routed around a limb and through the buckle assembly. From there, the strap can reverse direction such that the strap routes around at least a portion of the limb a second time and passes through the pulley assembly. A user can then apply a force to the distal end portion of the strap to tighten the tourniquet device around the limb, and the distal end portion of the strap can be secured in place with an attachment mechanism once a sufficient occlusive pressure is applied to the limb. When not in use, the tourniquet device can be worn (e.g., as a belt or restraint, integrated into clothing, etc.), such that the tourniquet device is conveniently stored, easily accessible in emergencies, and quickly applied to injuries. It will be appreciated that several of the details set forth below are provided to describe the following embodiments in a manner sufficient to enable a person skilled in the relevant art to make and use the disclosed embodiments. Several of the details described below, however, may not be necessary to practice certain embodiments of the new technology. Additionally, the new technology can include other embodiments that are within the scope of the claims but are not described in detail with reference to  FIGS. 1-7 . 
     Many of the details, dimensions, angles and other features shown in the Figures are merely illustrative of particular embodiments of the invention. For example, the shapes of various elements and angles are not drawn to scale, and some of these elements are arbitrarily enlarged and positioned to improve drawing legibility. Further, the particular shapes of the elements as drawn are not intended to convey any information regarding the actual shape of the particular elements, and have been solely selected for ease of recognition in the drawings. Accordingly, other embodiments can have other details, dimensions, angles and features without departing from the spirit or scope of the present disclosure. In addition, identical reference numbers are used in the Figures to identify identical or at least generally similar elements. To facilitate the discussion of any particular element, the most significant digit or digits of any reference number refers to the Figure in which that element is first introduced. For example, element  110  is first introduced and discussed with reference to  FIG. 1 . 
       FIG. 1  is a perspective view of an arterial tourniquet device  100  being tensioned around a person&#39;s limb  102  in accordance with embodiments of the new technology. The tourniquet device  100  can include a strap  104 , a buckle assembly  106 , and a pulley assembly  108 . The buckle assembly  106  can be secured to a proximal end portion  104   a  of the strap  104 , and the pulley assembly  108  can be movably coupled to the strap  104  such that the pulley assembly  108  can move along a length of the strap  104  to accommodate differently sized limbs (e.g., arms, legs, etc.). For example, the pulley assembly  108  can be moved closer to the buckle assembly  106  for smaller limbs (e.g., arms), and farther from the buckle assembly  106  for larger limbs (e.g., legs). Additionally, the pulley assembly  108  can be positioned along the strap  104  to gain additional leverage when tensioning the tourniquet device  100 . 
     The strap  104  can have a diameter D that can apply sufficient pressure to constrict or occlude blood flow from the limb  102 , while preventing the strap  104  from constricting the limb to the point of injury and/or amputation. In some embodiments, for example, the strap  104  can have a diameter of three inches. In other embodiments, the strap  104  can have a smaller diameter, a larger diameter, or vary in diameter. The strap  104  can be made from woven nylon (e.g., webbing), leather, plastic, rubber, cotton, and/or another suitable material that can withstand tension forces sufficient to cut off blood flow. 
     The tourniquet device  100  can further include an attachment mechanism  110  that can releasably secure a free portion (e.g., the distal end portion  104   b ) of the strap  104  to the tourniquet device  100 . As shown in  FIG. 1 , the attachment mechanism  110  can be strips of Velcro® (one strip visible in  FIG. 1 ) spaced along a circumference of the strap  104  at  110   a  and  110   b.  In other embodiments, the attachment mechanism can be a snap, a clip, and/or another suitable attachment mechanism that can releasably secure the strap  104  to the tourniquet device  100 . 
     In some embodiments, the pressure applied by the tourniquet device  100  to the limb  102  can be slowly and/or partially released to prevent damage to the limb  102  (e.g., gangrene), sudden blood loss, and/or renewed bleeding. Thus, the attachment mechanism  110  can be configured to allow for incremental loosening of the tourniquet device  100  and reattachment at each incremental pressure decrease. For example, the attachment mechanism  110  can include a plurality of fasteners (e.g., Velcro® Omnitape® strips) spaced around the strap  104  at  110   a  and  110   b,  or comprising the entire strap or a substantial length thereof, and/or a releasable fastener (e.g., a clip) that allow the strap  104  to be re-secured to the attachment mechanism  110  during each incremental pressure decrease. Similarly, the attachment mechanism  110  can also be used to incrementally increase pressure. 
     In an emergency, the tourniquet device  100  can completely encircle the limb  102  above the point of blood loss (e.g., a bullet hole), and preferably with the entire device  100  rotated about the limb as much as is necessary to align one of the two buckle/pulley assemblies with a major blood vessel. The distal end portion  104   b  of the strap  104  can be routed through the buckle assembly  106 , looped around the buckle assembly  106 , where the strap  104  can reverse direction. The strap  104  can at least partially encircle the limb  102  for a second time such that the distal end portion  104   b  can be routed through and around the pulley assembly  108 . The distal end portion  104   b  of the strap can be pulled away from the pulley assembly  108  to tension the strap  104 . The tension can transfer to the limb  102  such that the tourniquet device  100  applies circumferential pressure to the limb  102  to constrict or occlude blood flow from above the tourniquet device  100 . In addition, the pulley assembly  108  located over the blood vessel will have a portion which pushes into the flesh of the limb of the patient and directly pressure the blood vessel, aiding occlusion. (In the case of assembly  106 , the pulley member itself may in alternative embodiments be designed and configures so that it too digs downward, into the opening holding the limb ( 102 ), however this is not the presently preferred embodiment.) Assembly  108  (in particular the tray/pulley support member  212 , has a pulley member which pulls upward and thus torques/levers the edges of the assembly downward into the flesh. 
     In other alternative embodiments the tray  212  may be attached to the pulley at one edge (rather than near the middle as shown in  FIGS. 3A / 3 B) with a pinch bar/axle extending across the tray and no apertures ( 216   a,    216   b  are thus omitted) to grip the strap when the pulley is under tension upward away from the tray. In this embodiment, the pulley member in fact levers the tray  212  edge into the artery in a triangle or “V” shape quite effectively. 
     The pulley assembly  108  can approximately double the force exerted by a user on the tourniquet device  100  to the limb  102 . For example, if an occlusive pressure is X, the user need only exert approximately X/2 to adequately tension the tourniquet device  100  around the limb  102  and cut off blood flow. Once a desired pressure is reached (e.g., enough pressure to stop bleeding), the attachment mechanism  110  can releasably secure the distal end portion  104   b  of the strap  104  to the tourniquet device  100 . If desired, the pressure to the limb  102  can be released incrementally by reducing the tension on the strap  104  and re-securing the strap  104  to the attachment mechanism  110 . In operation, the tourniquet device  100  multiplies the force exerted by the user such that the tourniquet device  100  can be applied with one hand and can be used constrict or occlude the user&#39;s own blood flow. This can be especially advantageous when the user is injured and/or lacks the strength or dexterity necessary to achieve occlusive pressure. Advantageously, the tourniquet  100  device can also be used as a sling for a broken arm. For example, a user can encircle the strap  104  around his or her neck, and secure the strap at a desired length using the buckle assembly  106 , the pulley assembly  108 , and/or the attachment mechanism  110 . The user can then support his or her arm with the strap  104 . Additionally, the tourniquet device  100  can also be used to secure a splint in place by wrapping the strap  104  around the limb and the splint and tightening the tourniquet device  100  using the pulley assembly  108  and/or the buckle assembly  106 . Moreover, the tourniquet device  100  can find a wide variety of other uses consistent with the present invention and of those skilled in the art, including: being tied around a person&#39;s body and/or limbs to restrain the person (e.g., in combat situations), used to create an emergency evacuation litter, as a gun strap to carry a gun and can be used to create a backpack or as backpack straps or compression straps on a backpack. The tourniquet device  100  can also be used as tie down straps, towing straps, as a climbing harness, as a fixed loop for helicopter rescue, as an animal (e.g. dog) harness, animal leash, animal collar or animal restraint. 
     When the tourniquet device  100  is not in use, the tourniquet device  100  can be worn for convenient storage and quick accessibility. For example,  FIG. 2  is a perspective view of the tourniquet device  100  shown in  FIG. 1  worn as a belt in accordance with the new technology. The tourniquet device  100  can be looped around a torso  105 , through belt loops  103 , and can be secured using the buckle assembly  106 . The pulley assembly  108  can be moved along the length of the strap  104  such that the pulley assembly  108  to secure a loose end (e.g., the distal end portion  104   b ) in place. In an emergency, the tourniquet device  100  can quickly be removed from the torso  105  and secured around the limb  102 . Thus, when the tourniquet device  100  is not in use, the tourniquet device  100  can serve an additional functional purpose (e.g., a belt) that does not require additional storage. In other embodiments, the tourniquet device  100  can be worn and/or used with another article of clothing or accessory, such as a back pack strap. 
     In further embodiments, the tourniquet device  100  can be integrated into clothing at select locations (e.g., upper limb portions). For example, the tourniquet device  100  can encircle an upper thigh portion in each leg of a pair of pants and a detachable fabric portion can cover the strap  104 , the buckle assembly  106 , and/or the pulley assembly  108  for unobtrusive storage. In an emergency, a wearer must only remove the fabric portion to access and employ the tourniquet device  100  on his or her leg. Thus, the tourniquet device  100  can be conveniently stored around a limb for quick application in emergencies. In still further embodiments, the tourniquet device  100  can be integrated into or used as a vehicle restraint (e.g., a seat belt) and detached from the vehicle for use as a tourniquet. 
       FIG. 3  is an enlarged isometric view of the pulley assembly  108  shown in  FIG. 1 . The pulley assembly  108  can include a support member  212  and a pulley member  214  (shown at a first position  214   a  and at a second position  214   b ) rotatably connected to the support member  212 . NOTE again that the pulley member  214  is not a complete mechanical pulley but is rather an individual pulley/sheave/block. The support member  212  can include a first surface  212   a  and a second surface  212   a  opposite the first surface  212   a.  In the embodiment illustrated in  FIG. 3 , the support member has a substantially rectangular shape that has generally similar dimensions as the strap  104  (shown in  FIG. 1 ) and curved portions that can enclose a portion of the pulley assembly  108 . In other embodiments, the support member  212  can have different shapes suitable for supporting the pulley member  214 . 
     As shown in  FIG. 3 , the support member  212  can in some embodiments further include apertures  216  (identified individually as a first aperture  216   a  and a second aperture  216   b ) extending through the support member  212 . The apertures  216  can be sized to receive the strap  104 , and slidably attach the pulley assembly  108  to the strap  104 . In some embodiments, for example, the distal end portion  104   b  of the strap  104  can be routed from the second surface  212   a,  through the first aperture  216   a,  across a portion of the first surface  212   a  between the apertures  216 , and through the second aperture  216   b.  In other embodiments, the strap  104  can be woven through the apertures  216  in the opposite direction and/or the support member  212  can include more or less apertures  216  sized to receive the strap  104 . 
     The slidable attachment provided by the apertures  216  or other mechanisms allows the pulley assembly  108  to move along the length of the strap  104  such that the position of the pulley assembly  108  can change to accommodate differently sized limbs and/or provide better leverage to the user. When the pulley assembly  108  is at a desired position, the apertures  216  can substantially restrict the movement of the pulley assembly  108  to prevent it from moving as the tourniquet device  100  is tensioned. Additionally, as described with reference to  FIG. 2 , the slidable attachment provided by the apertures  216  allows the pulley assembly  108  to be moved when the tourniquet device  100  is used as a belt to secure loose, free end portions of the strap  104 . In other embodiments (discussed previously in reference to  FIG. 1 ) the apertures  216  may be omitted and the pulley member hinged portion  220  may be hinged much closer to one edge. 
     In other embodiments, the support member  212  can include other fasteners that allow the pulley assembly  108  to move along the length of the strap  104  to accommodate differently sized limbs and/or torsos. For example, in some embodiments, the support member  212  can include a clip having a push button that, when engaged, allows the pulley assembly  108  to move along the length of the strap  104  and, when released, substantially secures the pulley assembly  108  in the desired position. In further embodiments, the support member  212  can include clips, snaps, and/or other suitable fasteners that slidably and/or releasably secure the pulley assembly  108  to the strap  104 . In still further embodiments, the pulley assembly  108  can be detachable from the tourniquet device  100  when not in use and secured with a clip and/or other suitable fastener in an emergency. 
     The pulley member  214  can include a roller portion  218  rotatably coupled to a hinged portion  220  such that the roller portion  218  can spin 360° about the hinged portion  220 . As shown in the embodiment in  FIG. 2 , the hinged portion  220  can extend through the roller portion  218  to serve as a spindle for the roller portion  218 . In other embodiments, the hinged portion  220  can be rotatably coupled to end portions of the roller portion  218 . The hinged portion  220  can be rotatably coupled to the support member  212  with hinges, pins, and/or other suitable devices that allow the pulley member  214  to rotate. 
     In some embodiments, the pulley member  214  can be biased by a spring force and/or include a locking mechanism to move the pulley member  214  to specified positions. For example, the pulley member can be locked at an angle (e.g., 45°, 90°) away from the support member  212  while tensioning the tourniquet device  100  for optimal leverage on the strap  104 . As another example, the pulley member  214  can be biased toward the support member  212  such that the pulley member  214  is compactly stored when not in use. In other embodiments, the pulley member  108  can further include a cover (not shown) that encloses the pulley member  214  when it is not in use to prevent the pulley member  214  from catching on surroundings. 
     This bias to higher angles is especially useful to help provide targeted pressure directly to a specific blood vessel thereunder. By increasing the angle of the pulley members relative to the assemblies, a wider “V” or triangle shape is created and a greater arterial pressure may be applied. 
     As shown in  FIG. 3B , the hinged portion  220  and the roller portion  218  can form an opening  222  such that the strap  104  can be routed around the roller portion  218 . The roller portion  218  can have a length L that is at least the diameter D (shown in  FIG. 1A ) of the strap  104  such that the roller portion  218  can provide a contact point for the strap  104  when the tourniquet device  100  is tensioned. The roller portion  218  can be made from materials having low coefficients of friction to allow the strap  104  to smoothly glide over the roller portion  218 . In some embodiments, for example, the roller portion  218  can be made from smooth plastics, metals, and/or other substantially frictionless materials. Additionally, the entire pulley member  214  (e.g., the roller portion  218  and the hinged portion  220 ) can be made from a material able to withstand the forces applied to the pulley assembly  108  without substantial deformation. For example, the pulley member  214  can be made from metals, strong plastics, and/or other suitable materials. 
     As illustrated by the arrow in  FIG. 3A , the pulley member  214  can rotate with respect to the support member  212  from the first position  214   a  to the second position  214   b.  In the first position  214   a,  the pulley member  214  can be substantially flush and/or parallel to a first surface  212   a  of the support member  212 . The pulley member  214  can be rotated to the first position  214   a  for compact storage when the tourniquet device  100  is not in use. Additionally, the pulley member  214  can be placed in the first position  214   a  to secure a free end portion of a strap  104  under the pulley member  214 . In the second position  214   b,  the pulley member  214  can rotate away from the first surface  212   a  of the support member  212 . The pulley member  214  can be moved to the second position  214   b  during use as a tourniquet such that the strap  104  can be routed through the opening  222  and around the roller portion  218  to tension the strap  104  around a limb (e.g., the limb  102  described in  FIG. 1 ). In other embodiments, the pulley member  214  can rotate beyond the second position  214   b,  and/or rotate freely 180° from the first position  214   b  to be proximate to the apertures  216  at the first surface  212   a.  In further embodiments, the pulley member  214  can rotate more or less with respect to the support member  212 . 
     In selected embodiments, the pulley assembly  108  can also include a clamp mechanism that can (1) tension the tourniquet device  100  tighter around a limb as a user pulls more of the strap  104  through the clamp mechanism, and (2) retain that tension when the user releases the strap  104 . For example, the clamp can allow the strap  104  to pass substantially freely in one direction (e.g., tightening the tourniquet device  100 ) and can substantially prevent the strap  104  from passing in the opposite direction (e.g., loosening the tourniquet device  100 ). In additional embodiments, the clamp mechanism can also include a release feature, such as a button, knob, or other suitable manual or electronic release, that can be used to loosen the strap  104  from the clamp mechanism. 
     The pulley member  214  can reduce the amount of force required to attain a requisite pressure. For example, the pulley member  214  can reduce the force required by approximately half. This is especially helpful when the user applying the tourniquet device  100  is wounded himself and/or lacks the strength to apply the appropriate amount of pressure to slow or occlude bleeding. 
       FIG. 4  is an enlarged top view of the buckle assembly  106  shown in  FIG. 1 . The buckle assembly  106  can include a frame  324  and a post  326 . As shown in  FIG. 4 , the frame  324  can form an opening  328  such that the proximal end portion  104   a  of the strap  104  can be secured around a back portion  330  (shown in hidden lines) of the frame  324 . The proximal end portion  104   a  can be attached around the back portion  330  with thread, snaps, glue, and/or other suitable fasteners that can secure the proximal end portion  104   a  to the frame  324 . In other embodiments, the proximal end portion  104   a  of the strap  104  can be integrally formed. 
     The post  326  can extend across the opening  328 , substantially parallel to the back portion  330  of the frame  324 . In some embodiments, the post  326  can be slidably attached to the frame  324  such that the post  326  can adjust the width of the opening  328  to secure the strap  104 . In other embodiments, the post  326  can be fixedly attached to the frame  324  and/or the frame  324  and the post  326  can be a single piece. The frame  324  and the post  326  can be made from semi-rigid and/or rigid materials that can withstand the force applied to the tourniquet device  100  to occlude blood flow. For example, in some embodiments, the frame  324  and the post  326  can be made from steel alloys, strong plastics, and other suitable materials. 
     In operation, the distal end portion  104   b  of the strap  104  can be routed through the opening  328 , and the strap  104  can be looped around the post  326  and/or the frame  324  such that the strap  104  encircles a limb. If used as a belt, the distal end portion  104   b  can be woven around the buckle assembly  106  like a conventional box-frame belt buckle. 
       FIG. 5  is an enlarged back view of the buckle assembly  106  and the pulley assembly  108  shown in  FIGS. 1-4 . In the illustrated embodiment, the proximal end portion  104   a  of the strap  104  is secured to the back portion  330  of the frame  324 . The post  326  extends across the opening  328  formed by the frame  324  such that the distal end portion  104   b  (not visible) of the strap  104  can be woven through the buckle assembly  106 . The pulley assembly  108  can be slidably attached to the strap  104  by weaving the strap through the apertures  216 . In the embodiment illustrated in  FIG. 3 , the hinged portion  220  of the pulley member  214  is attached to the support member  212  with pins  432  (not visible) that allow the pulley member  214  to pivot with respect to the support member  212 . Additionally,  FIG. 1  shows the attachment mechanism  110  includes strips of Velcro® (shown individually as a first attachment mechanism  110   a  and a second attachment mechanism  110   b ) spaced along the strap  104  such that the tourniquet device  100  can be incrementally tightened or loosened. 
       FIGS. 6A and 6B  are isometric and top views, respectively, of a buckle assembly  606  configured in accordance with other embodiments of the new technology. The buckle assembly  606  includes features generally similar to the buckle assembly  106  described with reference to  FIG. 4 . For example, the buckle assembly  606  includes the frame  324 , the post  326 , and the opening  328  across which the post  326  extends. The back portion  330  of the frame  324  can be coupled to the proximal end portion  104   a  of the strap  104 . 
     In the embodiment illustrated in  FIGS. 6A and 6B , the buckle assembly  606  can further include a second pulley member  634 . NOTE yet again that the pulley member  634  is not actually a true pulley (it is a block/sheave/etc) BUT, with the strap running between the two pulley members on the two assemblies, a true pulley is formed and true mechanical advantage is achieved in a tourniquet. The second pulley member  634  can include features generally similar to the pulley member  214  described in  FIG. 2 . For example, the second pulley member  634  can include a roller portion  636  and a hinged portion  638  that are at least generally similar to the roller and hinged portions  218  and  220  described above. In the embodiment shown in  FIGS. 6A and 6B , the second pulley member  634  further includes a reinforcement member  640  that extends across the opening  328  and provides support for the second pulley member  634  when the strap  104  is tensioned around it. The reinforcement member  640  can be substantially parallel to the post  326 . In other embodiments, the second pulley member  634  second does not include the reinforcement member  640 , while in further embodiments the buckle assembly  606  includes additional reinforcement members  640 . 
     As shown in  FIG. 6A , the second pulley member  634  can extend downwardly away from the frame  324  such that the second pulley member  634  biases the buckle assembly  606  away from a limb (e.g., the limb  102  described above). The biased pulley member  634  can prevent the buckle assembly  606  from pinching skin on the limb during tensioning of the tourniquet device  100 . When the buckle assembly  606  is not in use, the second pulley member  634  can retract toward the frame  324  as shown in FIG.  6 B. In some embodiments, the second pulley member  634  can be biased further away from and/or closer toward the frame  324  than shown in  FIGS. 5A and 5B . In other embodiments, the second pulley member  634  can rotate about the frame  324 , and can be secured in desired positions using suitable locking mechanisms. In further embodiments, the second pulley member  634  can be freely hinged about the frame  324  and/or another portion of the buckle assembly  606 . In still further embodiments, the second pulley member  634  can be attached in a fixed position to a portion of the buckle assembly  606 . 
       FIG. 7  is a side view of the tourniquet device  700  in accordance with further embodiments of the new technology. The tourniquet device  700  can include features generally similar to the tourniquet device  100  described in  FIG. 1 . For example, the tourniquet device includes the strap  104 , the pulley assembly  108  having the support member  212  and the pulley member  214 . Additionally, the tourniquet device  700  includes the buckle assembly  606  described in  FIGS. 6A and 6B  that includes a pulley. Thus, the tourniquet device  700  shown in  FIG. 7  includes two pulleys: one on the pulley assembly  108  and another on the buckle assembly  606 . Advantageously, this double-pulley tourniquet device  100  can require even less force from a user to constrict or occlude blood flow. 
     As shown in  FIG. 7 , the tourniquet device  700  can form an opening  750  through which a limb can extend. The distal end portion  104   b  of the strap  104  can be routed through the buckle assembly  606  and around the second pulley member  634 . The second pulley member  634  can bias the buckle assembly  606  away from the skin to ensure the limb is not pinched when tensioning the tourniquet device  700 . The addition of the second pulley member  634  to the tourniquet device  700  can also reduce the amount of force exerted by the user to adequately tension the tourniquet device  700 . For example, the strap  104  can slide easily over the buckle assembly  606 , creating less friction, and thus requiring less force to obtain occlusive pressure. 
     As further shown in  FIG. 7 , the distal end portion  104   b  can be redirected to surround at least a portion of the limb a second time. The distal end portion  104   b  can then extend through the opening  222  formed by the pulley member  214  of the pulley assembly  108 . The tourniquet device  700  can be tensioned around the limb by pulling on the distal end portion  104   b  of the strap  104 . In the embodiment illustrated in  FIG. 7 , the pulley member  214  is locked in place an angle away from the support member  212  when the tourniquet device  700  is tensioned to provide better leverage. 
     As discussed in the GLOSSARY,  FIG. 8  is a block diagram of a simple pulley, illustrating the nature of a pulley. 
     From the foregoing, it will be appreciated that specific embodiments of the present technology have been described herein for purposes of illustration, but that various modifications may be made without deviating from the technology. For example, in the embodiments illustrated in  FIG. 1 , the pulley assembly  108  is positioned near the buckle assembly  106 . However, the pulley assembly  108  can be positioned anywhere along the strap  104  to achieve maximal leverage. Additionally, padding can be added to the tourniquet devices  100 ,  700  (e.g., on the strap  104 , on the support member  212 ) described in  FIGS. 1-7  to provide additional comfort for an injured person. Certain aspects of the new technology described in the context of particular embodiments may also be combined or eliminated in other embodiments. For example, the tourniquet devices  100 ,  700  described in  FIGS. 1-7  can include additional pulley members and/or additional pulley assemblies. Further, while advantages associated with certain embodiments of the new technology have been described in the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments need necessarily exhibit such advantages to fall within the scope of the technology. Accordingly, the disclosure and associated technology can encompass other embodiments not expressly shown or described herein.