Patent Publication Number: US-2023139679-A1

Title: Tourniquet devices, systems and methods for using the same

Description:
TECHNICAL FIELD 
     The present disclosure relates to devices, systems, and methods of using emergency tourniquets that comprise easy to use and accurate means of recording initiation time and tracking treatment time. Further, certain embodiments relate to devices for medical emergencies in one or more applications such as, without limitation, military and pre-hospital emergency applications, and methods of operating said devices. 
     BACKGROUND 
     Generally, a tourniquet is a device for stopping the flow of blood through a vein or artery, typically by compressing a limb or other body portion with a cord or tight bandage. Elimination of distal artery flow is the primary purpose of a tourniquet. Most commercially manufactured tourniquets comprise some form of an encircling cuff that can be applied to a limb proximal to an exsanguination site and sufficiently tightened such that sufficient pressure is achieved to stop arterial and venous blood flow past the cuff (i.e. obliterating the distal pulse). 
     There are many types of conventional tourniquets. Clinical tourniquets can be simple elastic bands used in a hospital or clinical setting for diagnostic and interventional purposes. Such tourniquets are commonly used in peripheral intravenous access insertion and blood extraction, but typically cannot achieve the requisite pressures to stop arterial bleeding. For example, a clinical tourniquet can be tightened just enough to permit blood to collect in a vein to be accessed, but is typically not suitable in a triage setting. 
     In contrast, surgical tourniquets are typically used by surgeons or other health care practitioners to facilitate surgical procedures on upper and lower limbs; in use these tourniquets are deployed to establish a bloodless operative field in a limb distal to an encircling cuff by regulating a pressure applied to the limb by the cuff near a pressure sufficient to stop arterial blood flow past the cuff. Such tourniquets often comprise an inflatable pneumatic cuff that can produce enough pressure to impede blood flow, but can easily be decompressed if the pressure needs to be relieved. Often, surgical tourniquets also comprise an automatic pressure regulator and/or the pneumatic mechanism is electrically powered such that the tourniquet itself comprises wires and other electrical components. 
     Emergency tourniquets are the third type of tourniquets and are typically carried by military medics, paramedics, and rescue personnel. Conventional emergency tourniquets do not comprise electrical componentry, but are instead lightweight, sturdy, and durable bands or straps that can be applied quickly and, often, single-handedly. Examples of emergency non-pneumatic tourniquets are a combat application tourniquet (CAT) and a ratchet tourniquet. A conventional CAT tourniquet consists of a hook-and-loop, closed-loop fastener belt attached to a windlass mechanism, and is among the most widely used tourniquets in the United States Army. The CAT is designed for rapid, one-handed self-application in the field and is applied by manually twisting the belt with the windlass. Similar to the CAT, a traditional ratchet tourniquet forms a loop that must be fed over the injured limb and advanced upward past the injury before tightening high up on the limb. Unlike the plastic and cloth assembly of the CAT, the metal ratchet mechanism of a ratchet tourniquet forms a strong bond that is unlikely to dislodge with even the roughest handling. Pneumatic tourniquets have also been developed for military and emergency use, based on surgical designs considerations. While these tourniquets typically do not comprise electrical componentry and regulators like conventional surgical tourniquets, they do comprise a wide cuff coupled with a windlass and a hand bulb pump. In one such pneumatic tourniquet design, the emergency and military tourniquet (EMT), a hand pump is manually inflated to create pressure and stop bleeding. 
     When tourniquets are applied, the potential for injury is significant when protocols are not rigorously followed. Preventing arterial blood flow to a limb will result in ischemia. Continuous tourniquet application can, for example, result in permanent nerve injury, gangrene, muscle injury (including contractures, rhabdomyolysis, and compartment syndrome), vascular injury, skin necrosis, clot, significant pain, reperfusion injury, and even amputation of the limb. 
     There is no consensus on an absolutely safe duration for tourniquet use, however, a range of 1-3 hours has been suggested, with 2 hours largely considered a useful guideline for safe usage during elective surgery. It has also been suggested that the effects of traumatic injury and blood loss (e.g., due to an injury during combat and/or where the patient has suffered a medical trauma) can reduce the ischemic tolerance of the limb in comparison to elective surgery, suggesting that safe tourniquet times may be shorter than expected. especially for patients in shock. 
     In general, minimizing the tourniquet time is the most effective strategy to minimize the risks of tourniquet-related injury. Along these lines, accurately tracking how long the tourniquet has been applied to a patient is critical information for not only preventing permanent damage to the patient&#39;s limb, but also enabling a healthcare provider to quickly and accurately assess the most pressing risk to the patient upon assumption of care. For example, where an emergency tourniquet is applied in a field triage setting, it is extremely important that a receiving healthcare team is provided with an accurate duration of use of the tourniquet so that an accurate risk assessment can be performed in determining the proper, and most urgent, course of treatment. The current standard of care is that an initiation time is handwritten (e.g., with a marker) on the tourniquet when applied. As an emergency tourniquet is often applied in the field at a time of high stress for everyone involved, the likelihood of an accurate and legible time being recorded on the tourniquet and thereafter remaining visible and legible is often low. 
     Accordingly, devices and methods that can reliably and accurately record the duration of tourniquet application are needed. Ideally, such devices and methods should be cost effective to manufacture, tamper resistant, and simple to use in a field environment. 
     SUMMARY 
     Tourniquets configured for emergency and/or field (non- or pre-hospital) that facilitate the simple and accurate tracking of elapsed treatment time are provided. In certain embodiments, such a tourniquet comprises a flexible band for encircling and applying pressure to a limb of a patient, a fastening element for securing a first portion of the flexible band to a second portion of the flexible band, a tensioning device operative to apply tension to the flexible band, and a timer apparatus. The tensioning device of the tourniquet can comprise any tensioning device now known or hereinafter developed that is appropriate for use with the tourniquet designs described herein. In certain embodiments, the tensioning device comprises at least one of a ratchet, a windlass, a slip buckle, a frictional bias means, a hook-and-loop fastener and a hand bulb pump. In certain embodiments, the tensioning device does not comprise electrical circuitry or otherwise require a pump or actuator. In certain embodiments, the tourniquet is configured for single-handed, self-application. 
     In certain embodiments, the timer apparatus is affixed to the flexible band (e.g., removably affixed or semi-permanently affixed or securely, albeit removably, affixed). In certain embodiments, the timer apparatus is integrally formed with the flexible band (i.e. integral with the flexible band). 
     The timer apparatus can comprise a housing, a display coupled with the housing, a power supply, a switch operatively controlled externally to the housing, and a microcontroller responsive to closure of the switch and in electrical communication with the display. In certain embodiments, the housing of the timer apparatus is formed of the following materials and/or configured to be one or more of shock resistant, waterproof, or water resistant. The timer apparatus can be configured such that, once activated, the timer cannot return to the inactive condition without opening the housing (e.g., where the housing is not configured to be opened, by breaking the housing or forcing the housing to open) or exhausting the power supply. 
     In certain embodiments, the power supply of the timer apparatus comprises one or more batteries. 
     In certain embodiments, the microcontroller of the apparatus can be mounted on a printed circuit board and in electrical communication with a voltage regulator; however, it will be understood that various acceptable configurations can be employed by one of ordinary skill in the art to achieve the same design outcome. 
     In operation, closing the switch of the timer apparatus can initiate voltage flow between the power supply and the microcontroller, thereby activating the microcontroller to measure elapsed time starting from activation. In certain embodiments, the switch of the timer apparatus comprises an activating component that is removably attachable to the housing and which closes the switch upon removal. In certain embodiments, when the activating component is attached to the housing, the switch is open and the microcontroller is in an inactive condition. The activating component can comprise a release pin, a release tab, or a similar design that is positioned between the microcontroller and the power supply when attached to the housing. In certain embodiments, the activating component is configured for single use. 
     Tourniquet systems are also provided. Such a tourniquet system can comprise any of the tourniquets described herein or otherwise conventional tourniquets wherein a timer apparatus of the present disclosure is coupled therewith. For example, certain embodiments of a tourniquet system comprise a tourniquet comprising a flexible band for encircling and applying pressure to a limb of a patient, a fastening element for securing a first portion of the flexible band to a second portion of the flexible band, and a tensioning device operative to apply tension to the flexible band. Additionally such systems comprise a timer apparatus coupled with the tourniquet, wherein the timer apparatus comprises: a housing, a display coupled with the housing, a power supply positioned within the housing, a switch (e.g., single-use switch) operatively controlled externally to the housing, and a microcontroller responsive to closure of the switch, positioned within the housing, and in electrical communication with the display. The switch can comprise an activating component operable to close the switch upon removal and closure of the switch can initiate voltage flow between the power supply and the microcontroller, thereby activating the microcontroller to measure elapsed time starting from activation. 
     In certain embodiments the display of the timer apparatus comprises a digital display, the power supply comprises one or more batteries, the microcontroller of the timer apparatus is mounted on a printed circuit board and in electrical communication with a voltage regulator, the activating component of the switch comprises a pin or a tab, and the pin or tab is positioned between the microcontroller and the power supply when attached to the housing such that the microcontroller is in an inactive state. 
     Methods of applying a tourniquet using the devices and systems hereof are also provided. In at least one embodiment, a method of applying a tourniquet comprises: providing a constriction device comprising a flexible band, a fastening element for securing a first portion of the flexible band to a second portion of the flexible band, a tensioning device operative to apply tension to the flexible band, and a timer apparatus coupled with the flexible band, the timer apparatus comprising: a housing, a display coupled with the housing, a power supply, a switch operatively controlled externally to the housing and comprising an activating component that is removably attachable from the housing and operable to close the switch upon removal; manipulating the flexible band around a body part of a patient; coupling the first end of the flexible band with the second end of the flexible band to encircle the body part; adjusting the tensioning device to apply constrictive pressure around the body part sufficient to restrict at least arterial blood flow through the body part; and removing the activating component from the timer apparatus to activate the microcontroller and initiate tracking of elapsed time of treatment. In certain embodiments, the step of manipulating the flexible band and adjusting the tensioning device can be performed single-handedly. 
     In certain embodiments, the method can further comprise displaying an elapsed tourniquet time on the display, the elapsed tourniquet time associated with the time elapsed since the timer was activated. Removing the activating component from the timer can be performed, for example, immediately following adjusting the tensioning device to apply constrictive pressure around the body part. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosed embodiments and other features, advantages, and aspects contained herein, and the matter of attaining them, will become apparent in light of the following detailed description of various exemplary embodiments of the present disclosure. Such detailed description will be better understood when taken in conjunction with the accompanying drawings, wherein: 
         FIG.  1    shows a partial view of a tourniquet of the present disclosure; 
         FIG.  2    shows a flexible band of a tourniquet or tourniquet system of the present disclosure; 
         FIG.  3    shows a top, planar view of a timer apparatus of the present disclosure; 
         FIG.  4    shows a schematic diagram representative of the components of the timer apparatus shown in  FIG.  3   ; and 
         FIG.  5    shows a schematic diagram illustrating the voltage flow through the components of the timer apparatus shown in  FIG.  3    when in the activated condition, wherein the placement of the activating component  312  when the timer apparatus is in an inactive condition is represented by a dotted line. 
     
    
    
     While the present disclosure is susceptible to various modifications and alternative forms, exemplary embodiments thereof are shown by way of example in the drawings and are herein described in detail. 
     DETAILED DESCRIPTION 
     For the purposes of promoting an understanding of the principles of the present disclosure, reference will now be made to the embodiments illustrated in the figures and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of this disclosure is thereby intended and that specific details are set forth, such as particular embodiments, procedures, techniques, etc. to provide a thorough understanding of the present disclosure. However, it will be apparent to one skilled in the art that the present invention may be practiced in other embodiments that may depart from these specific details. 
     The present disclosure provides novel tourniquets and tourniquet systems that comprise easy-to-use tamper-proof and accurate timing components. Such devices allow for the recordation of an accurate time of initiation in manner that is simple to effect at the time of treatment (which is often high stress). In one embodiment, technical features described herein can be used to construct various embodiments of a tourniquet device. In one approach, the tourniquet comprises a timer apparatus affixed to or integral with a tourniquet, such as a one-handed self-applying tourniquet. Straightforward and dependable methods are also provided for conveying an accurate elapsed time of occlusion to downstream healthcare workers (e.g., upon hospital disposition following trauma care) following the application of a tourniquet in a field setting, for example. In ground-based tactical situations and prehospital or emergency settings, tourniquets can be used as life-saving hemorrhage control devices. Indeed, the immediate threat to life with an actively hemorrhaging extremity injury is addressed with the liberal use of tourniquets. However, an improperly used tourniquet can cause loss of the limb, compromised limb salvage, and systemic effects harmful to the patient, all of which may result from excess pressure or prolonged, continuous tourniquet time. The longer the tourniquet is in place, the more tissue destruction occurs and the higher the risk for injury (including, for example, reperfusion injury and kidney failure) and the general rule of thumb is reassessment of a tourniquet should occur as soon as the tactical situation permits, but no more than two hours after initial placement. 
     Excessive occlusion time can result from prolonged transport/evacuation times, or medical attendants at the next level of care either not being aware a tourniquet was applied or not knowing when the tourniquet was applied. As the length of time a tourniquet is applied is highly relevant to risk assessment for the patient, conventional protocols require the individual or healthcare provider applying the tourniquet to mark an initiation date and time on the tourniquet or the patient&#39;s head or limb with a marker. However, due to the nature of trauma care, it is often difficult for the person applying the tourniquet to record the date/time information legibly, if at all. Further, due to the very nature of the circumstances in which tourniquets are required, there is quite often blood and other materials present that can distort, obscure, or wash off the handwritten information. With conventional emergency tourniquets there is no guarantee that when the patient is delivered to a hospital or secondary care setting, the receiving healthcare providers will receive or be able to interpret any date/time information provided and, as such, accurately assess patient risk. 
     While recordation and tracking of elapsed tourniquet time has largely been addressed in the surgical setting with the pneumatic surgical tourniquet commonly used in most modern operating rooms (which includes a tourniquet microprocessor-based controller that supply and/or regulate pressure and a pneumatic tourniquet cuff applied to the limb), use of these complex devices is typically not available or practical in pre-hospital, emergency, and military settings. For example, instead of a surgical team of multiple individuals applying the tourniquet to a patient within a sterile surgical field, emergency tourniquets are commonly configured for self-application in a pre-hospital setting, and often for single-handed application (e.g., where the afflicted limb is an arm). Further, it is not practical for individuals to carry a pneumatic surgical tourniquet on their person when in the field. 
     The novel tourniquets of the present disclosure address these issues. Now referring to  FIG.  1   , a tourniquet  100  of the present disclosure is shown. The tourniquet  100  comprises a flexible band  102  comprising a fastening element  104 , a tensioning device  106 , and a timer apparatus  108 . 
     The flexible band  102  is configured for encircling and applying pressure to a limb of a patient and can be opened ended or a closed-loop band. In certain embodiments, the flexible band  102  can be a strap, a belt, an elastic band, or a cuff (e.g., an inflatable cuff having a hollow interior). The flexible band  102  can be any diameter in width and length, as needed. In certain embodiments, the flexible band is at least about 1.0 inches in width, between about 1.0 inches and 2.0 inches, and/or between about 1.5 inches and 2.0 inches (e.g., 1.5 inches, 1.6 inches, 1.7 inches, 1.8 inches, 1.9 inches, 2.0 inches, 2.5 inches, etc.). In some instances, wider flexible bands  102  can be better tolerated by a patient and are less likely than narrower bands (e.g., less than 1 inch wide) to cause damage to underlying structures such as nerves and soft tissue present within the underlying limb. 
     The flexible band  102  can be stretchable so that it can be wrapped around the limb and thereby compress the limb in use. In certain embodiments, the flexible band  102  has a spring constant such that it can be stretched enough to exert sufficient pressure on a limb to exceed the blood pressure causing bleeding. The spring constant can be in the range of, for example, about 1 N/m to about 300 N/m or as is otherwise known in the medical arts. A tourniquet  100  used to control arterial bleeding should be able to exert enough pressure to overcome the arterial systolic pressure, for example, 80 mmHg, 100 mmHg, 120 mmHg, 150 mmHG, and/or 200 mmHg. 
     The flexible band  102  can be made from a sheet or strip of material suitable for tourniquet applications, including, without limitation, a synthetic polymer nylon, grow ribbon, elastic, polyester, hook and loop fastener material or any combination thereof. Non-limiting examples of hook-and loop-fastener material is Velcro®, or self-engaging fastener material which is material with hook and loop woven on the same surface such as snag-free fasteners known as Omni-tape®. The flexible band  102  can also be made from a thermoplastic body material, for example, comprising or including polypropylene. The flexible band  102  can be formed as a single piece or section of such material or as any combination of sections or straps of the material, as needed. 
     In certain embodiments, the flexible band  102  is made from a webbing material, such as that typically used in seat belt webbing. The webbing can be polyester webbing or a webbing made from, or including, a synthetic polymer (e.g., nylon). 
     As shown in  FIG.  2   , in certain embodiments, the flexible band  102  can have a first end  102   a  and a second end  102   b  opposite the first end  102   a , where the first and second ends  102   a ,  102   b  are configured to engage with each other via the fastening element  104 . In the embodiment shown in  FIG.  2   , the flexible band  102  is generally elongated and planar in configuration and has a hollow longitudinal interior. In other example, other shaped configurations can be adopted. 
     The fastening element  104  is either integral with or coupled with the flexible band  102  and is for securing the flexible band  102  around the underlying limb to be treated. For example, the fastening element  104  can be a fastener configured to releasably interconnect the first and second ends  102   a ,  102   b  of the flexible band  102  together (see, e.g.,  FIG.  2   ). 
     The fastening element  104  can be any type of fastener known or future developed that is capable of releasably closing the flexible band  102  in a loop around the limb to be treated. Numerous configurations and designs of fastening elements  104  are known in the tourniquet arts and any of which that are suitable for emergency, field, and/or pre-hospital application can be applied in the present context. For example, the fastening element  104  can comprise a pair of mating members configured to releasably attach to one another, such as, for example, a hook-and-loop fastener. The hook-and-loop fastener can be made of a polyester, polypropylene, aramid, stainless steel, or any other suitable material or combination of the foregoing to suit desired performance characteristics. In the embodiment shown in  FIG.  1   , at least one hook strip is attached on an inner surface of a first portion of the band  102  and the mating loop strip is attached along an outer surface of a second portion of the band  102  such that the fastener  104  releasably engages itself when in physical contact and holds the flexible band  102  in a loop configuration. 
     In other embodiments, the fastening element  104  can be made from Velcro® or a snag-free, self-engaging fastener material known as Omni-tape®. In other embodiments, the fastening element  104  can comprise snapping buttons or other hardware such as a buckle. At least a portion of the fastening element  104  can be slidable along the flexible band  102  (e.g., a slider component), and/or some or all of the fastening element  104  can be fixedly attached to the flexible band  102 . 
     The tourniquet  100  further comprises a tensioning device  106  operative to apply tension to the flexible band  102 . In use, when the flexible band  102  is positioned around a limb, the tensioning device  106  can adjust the flexible band  102  loop circumference and thereby the tension of the band  102  around the underlying limb. In this manner, the tensioning device  106  can apply constrictive pressure around the body part sufficient to restrict arterial blood flow through the body part. 
     The tensioning device  106  can be any tourniquet tensioning device now known or hereinafter developed including, without limitation, a windlass mechanism (e.g., a retractable windlass bar or other mechanism), a ratchet, a slip buckle, a frictional bias means, and/or a pneumatic hand pump. 
     In certain embodiments, the fastening element  104  and the tensioning device  106  can be a single component (e.g., a ratchet or a slip buckle) operable to both secure the flexible band  102  around the targeted area (e.g., limb) of the patient and also apply tension to the flexible band  102  such that circumferential pressure is applied to the limb. It will be appreciated that, in certain embodiments, the flexible band  102 , the fastening element  104 , and the tensioning device  106  can comprise any conventional tourniquet configuration that is suitable for emergency use and/or use in a pre-hospital setting. In at least one embodiment, the tourniquet configuration suitable for emergency use and/or in a pre-hospital setting has a tensioning device  106  that does not comprise electrical circuitry. 
     The tourniquet  100  further comprises a timer apparatus  108  coupled with the flexible band  102 . As shown in  FIGS.  3  and  4   , the timer apparatus  108  comprises a housing  302 , a display  304  coupled with or otherwise visible by a user through the housing  302 , a power supply  306 , a switch  308 , and a microcontroller  404  responsive to closure of the switch  308  (e.g., to measure/count and record elapsed time). As noted above, the switch  308  of the timer apparatus  108  can comprise an activating component  312  that is removably attachable to the housing  302  and which closes the switch  308  upon removal. 
     The housing  302  generally encases at least the electrical components of the timer apparatus  108 , can be formed of any suitable material(s), and can be a single integral component or two or more panels or portions coupled together (via a hinge, a fixed joint, a combination thereof, or via another connection). In certain embodiments, the housing  302  comprises a plastic case, a silicon case, a metal case, or a combination of any of the foregoing. In certain embodiments, the housing  302  can be made of a waterproof or water-resistant material, a hypoallergenic material, a flame-resistant material, a shock resistant material, or a combination of one or more of the foregoing. 
     In at least one embodiment, the housing  302  comprises a plastic case with a silicon cover that provides protection against impact. In certain embodiments, the housing  302  comprises acrylonitrile butadiene styrene (ABS). In certain embodiments, the housing  302  is flame-resistant (e.g., having a flammability rating of UL94V-0, UL9HB, and/or MVSS 302). 
     In certain embodiments, a bottom portion  302   b  of the housing  302  comprises an attachment means  314  for coupling the timer apparatus  108  to the flexible band  102  of the tourniquet  100 . In certain embodiments, the attachment means  314  comprises a hoop-and-loop fastening material (e.g., Velcro®), wherein a compatible material is present on the flexible band  102  at a targeted point of attachment. In this manner, the timer apparatus  108  can be removably coupled with the flexible band  102  simply by aligning the fastening materials and applying pressure. The attachment means  314  can also comprise an adhesive (permanent or otherwise) applied to the bottom portion  302   b  of the housing  302  such that the housing  302  can be adhered to the flexible band  102  or another portion of the tourniquet  100 . 
     The display  304  of the timer apparatus  108  can be any display now known or hereinafter developed that can visually display a representation of the counter of the microcontroller  404 . For example, the display  304  can be an analog or digital display similar to a stopwatch or watch face. For example, the display  304  can comprise a digital screen that displays four digits, representative of “Hr Hr:Min Min” such as, without limitation, a 4-element display that can count from 00:00 to 59:59. In certain embodiments, the display  304  comprises a light-emitting diode (LED) display. In certain embodiments, the display  304  comprises a liquid-crystal display (LCD). 
     The display  304  can be integral with a top portion  302   a  of the housing  302  and/or some or all of the top portion  302   a  of the housing  302  can be transparent such that, when the display  304  is encased within the housing  302 , the display  304  remains visible through the transparent portion of the housing  302  such that the timer/counter can be easily visualized. In certain embodiments, at least a portion of the display  304  is coupled with or affixed to the exterior of the housing  302  (e.g., the electrical components of the display  304  can be encased within the housing, with the screen/display portion affixed to and/or integral with an exterior of the top portion  302   a  of the housing  302 ). The display  304  can be sized and positioned to facilitate ease of viewing and any size dimensions of the display can be utilized as desired provided the timer apparatus  108  can be suitably affixed to the flexible belt  102  of the tourniquet  100 . In certain embodiments, the display  304  can be about 1 inch wide and about 0.5 inches tall. In other embodiments, the display  304  about 2 inches wide and about 1 inch tall. 
     The timer apparatus  108  further comprises a power supply  306 , which powers a microcontroller  404  that is electrical communication with the display  304  when the switch  308  is closed. The power supply  306  can be any suitable power source such as, for example, one or more standard batteries (e.g., a coin cell battery, a button cell battery, a 1.5V or 3V battery, a 5V battery, a 9V battery, a 12V battery, etc.). It will be appreciated that the number and voltage of batteries required and/or desirable can depend on the working voltage of the circuit utilized in the timer apparatus  108 . 
     The microcontroller  404  can be any type of microcontroller capable of performing a time-count in minutes and hours upwards from 00:00 (out of initial) to 59:59 when activated for measuring elapsed time. In certain embodiments, when activated, the microcontroller  404  does not stop, but instead repeats the counting after every full 60-hour cycle unless moved to an inactive condition as described below. In certain embodiments, the microcontroller  404  is an 8-bit microcontroller, a 16-bit microcontroller, or any other size/type of microcontroller as required. In at least one embodiment, the microcontroller  404  is an 8-bit 8051 microcontroller (e.g., a MCS-51 microcontroller). 
       FIG.  4    shows a schematic of one example of the internal circuitry of the timer apparatus  108 . In certain embodiments, the microcontroller  404  is mounted on a circuit board  402  (e.g., a printed circuit board). Certain embodiments can also comprise a voltage regulator  406  and a springboard mechanism  408  that are in electrical communication with the microprocessor  404 . The timer apparatus  108  can additionally include one or more transistors, capacitors and/or resistors (not shown) as is known in the art and may be desirable. Further, the microcontroller  404  can be coupled with any additional electrical circuitry or components now known or hereinafter developed provided the microcontroller  404  can be used to measure elapsed time when activated (i.e. in the active condition), encased within the housing  302 , and used in connection with the power supply  306  and switch  308  mechanisms described herein. 
     In certain embodiments, the power supply  306  is connected in series with the switch  308  and the switch  308  is operatively controlled externally of the housing (e.g., via the activating component  312 ). When the switch  308  is open, the microcontroller  404  of the timer apparatus  108  is in an inactive condition; however, closure of the switch  308  initiates voltage flow between the power supply  306  and the microcontroller  404  and activates the measurement of elapsed time from the initial value (i.e. the active condition).  FIG.  5    shows a schematic diagram indicative of voltage flow between the various components of the timer apparatus  108 . 
     In embodiments where the switch  308  comprises an activating component  312 , in the inactive condition, the activating component  312  is seated between the microcontroller  404  and the power supply  306 , which either keeps the power supply  306  disconnected from the rest of the circuit (i.e. the microcontroller  404 ) or in which the circuit is consuming the lowest quiescent current. The activating component  312  can be, for example, a pull pin or pull tab formed of nonconductive material that is slidable in an axial direction out of its seating. In certain embodiments, the microcontroller  404  is normally in the “inactive” condition. 
     To initiate the counting functionality of the microcontroller  404  (for example, for measurement of elapsed time), the switch  308  is closed. For example, when the activating component  312  is removed (i.e. slidably pulled from its seating), the switch  308  closes and the power supply  306  is connected to the microcontroller  404 /display  304  such that the microcontroller  404  initiates (see, e.g.,  FIG.  5   ). Notably, in certain embodiments, once deployed, the timer remains in the “active” condition (i.e. measuring elapsed time) until either the power supply  306  is exhausted or the housing  302  is disassembled and the switch  308  is manually opened; in other words, the switch  308  is not reversible and/or configured for a single use (inactive condition to active condition). In this manner, the timer apparatus  108  is not vulnerable to being erroneously stopped and a user can assure an accurate elapsed time measurement is obtained and visible through the display  304 . 
     In addition to the tourniquet  100  described above, tourniquet systems are also provided. The tourniquet system may comprise any tourniquet now known or hereinafter developed (e.g., an emergency tourniquet comprising a tensioning device that does not comprise electrical circuitry) having a timer apparatus  108  (previously described) affixed thereto. In certain embodiments, the timer apparatus  108  is configured for retrofit application to the band or cuff of the tourniquet. Alternatively, at least a portion of the housing  302  of the timer apparatus  108  can be integrally formed with a portion of the tourniquet (e.g., the band or cuff). 
     Tourniquet systems of the present disclosure can additionally comprise any tourniquet now known or hereinafter developed, a timer apparatus  108 , and an attachment means (not shown). As previously noted, the timer apparatus  108  is formed as previously described. The attachment means can be any attachment means capable of securely affixing the timer apparatus  108  to a portion of the tourniquet and, in certain embodiments, comprises a hook-and-loop fastener or an adhesive. In some embodiments, the attachment means can comprise a first portion for application to the tourniquet and a second portion either already affixed to the bottom portion  302   b  of the housing  302  of the timer apparatus  108  or configured for application to the bottom portion  302   b  of the housing  302  of the timer apparatus  108  (e.g., a first Velcro® patch or strip and a second Velcro® patch or strip compatible with the first Velcro® patch or strip). 
     Methods for using the tourniquets or tourniquet systems described herein are also provided. In certain embodiments, a method of using a tourniquet comprises manipulating the flexible band  102  of a tourniquet  100  (or a conventional tourniquet) around a body party of a patient; coupling the first end  102   a  of the flexible band  102  with the second end  102   b  of the flexible band  102  to encircle the body part; adjusting the tensioning device  106  to apply constrictive pressure around the body part sufficient to restrict at least arterial blood flow through the body part; and removing the activating component  312  from the timer apparatus  108  to activate the microprocessor  404  and, thus, initiate tracking of elapsed time of treatment (i.e. from initiation time). In certain embodiments, removing the activating component  312  from the timer apparatus  108  is performed immediately following adjusting the tensioning device  106  of the tourniquet to apply constrictive pressure around the body part. In certain embodiments, manipulating the flexible band  102  and adjusting the tensioning device  106  are performed single-handed. 
     In certain embodiments, removing the activating component  312  from the timer apparatus  108  is irreversible. In other words, when the switch  308  is closed and the microprocessor  404  moves from the inactive (resting) condition to the active condition, the timer apparatus  108  design does not support reinsertion of the activating component  312  to re-open the switch  308  such that the microprocessor  404  is back in the inactive condition and ceases counting. Instead, the only way to stop the counting functionality of the microprocessor  404  once initiated is to either exhaust the power supply  306  or manually open the switch  308  via direct access (i.e. opening the housing  302  and opening the switch  308  manually). This design feature ensures that the timing apparatus  108  cannot be moved to the inactive condition erroneously once initiated (e.g., if bumped or jostled during transport of the patient or during administration of an additional treatment to the patient). 
     The present disclosure relates to devices, systems, and methods of using emergency tourniquets that comprise easy to use and accurate means of recording initiation time and tracking treatment time. Further, certain embodiments relate to devices for medical emergencies in one or more applications such as, without limitation, military and pre-hospital emergency applications, and methods of operating said devices. 
     As used herein and in the appended claims, the singular forms “a,” “and,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a battery” includes a plurality of such batteries. The term “about,” when referring to a number or a numerical range, means that the number or numerical range referred to is an approximation within experimental variability (or within statistical experimental error), and thus the number or numerical range may vary between 1% and 15% of the stated number or numerical range. The term “comprising” (and related terms such as “comprise” or “comprises” or “having” or “including”) is not intended to exclude an embodiment of any compound, composition, method, process, or the like that may “consist of” or “consist essentially of” the described features. The invention illustratively described herein may be suitably practiced in the absence of any element(s) or limitation(s), which is/are not specifically disclosed herein. 
     A “patient” as the terms are used herein is a mammal. While preferably a human, the terms can also refer to a non-human mammal, such as a mouse, cat, dog, monkey, horse, cattle, goat, or sheep, and is inclusive of male, female, adults, and children. 
     The term “treatment” as used herein includes curative and/or prophylactic treatment. More particularly, curative treatment refers to any of the alleviation, amelioration and/or elimination, reduction and/or stabilization (e.g., failure to progress to more advanced stages) of a symptom, as well as delay in progression of a symptom of a particular disorder. Prophylactic treatment refers to any of the following: halting the onset, reducing the risk of development, reducing the incidence, delaying the onset, reducing the development, and increasing the time to onset of symptoms of a particular disorder. 
     Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of skill in the relevant arts. The terms and expressions, which have been employed, are used as terms of description and not of limitation. In this regard, where certain terms are defined, described, or discussed in the “Detailed Description,” all such definitions, descriptions, and discussions are intended to be attributed to such terms. There also is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof. Although any methods and materials similar to or equivalent to those described herein can be used in the practice or testing of the subject of the present application, the preferred methods and materials are described herein. 
     While various embodiments of devices, systems, and the methods hereof have been described in considerable detail, the embodiments are merely offered by way of non-limiting examples. Many variations and modifications of the embodiments described herein will be apparent to one of ordinary skill in the art in light of the disclosure. It will therefore be understood by those skilled in the art that various changes and modifications may be made, and equivalents may be substituted for elements thereof, without departing from the scope of the disclosure. Indeed, this disclosure is not intended to be exhaustive or too limiting. The scope of the disclosure is to be defined by the appended claims, and by their equivalents. 
     Further, in describing representative embodiments, the disclosure may have presented a method and/or process as a particular sequence of steps. However, to the extent that the method or process does not rely on the particular order of steps set forth herein, the method or process should not be limited to the particular sequence of steps described. As one of ordinary skill in the art would appreciate, other sequences of steps may be possible. Therefore, the particular order of the steps disclosed herein should not be construed as limitations on the claims. In addition, the claims directed to a method and/or process should not be limited to the performance of their steps in the order written, and one skilled in the art can readily appreciate that the sequences may be varied and still remain within the spirit and scope of the present disclosure. 
     It is therefore intended that this description and the appended claims will encompass, all modifications and changes apparent to those of ordinary skill in the art based on this disclosure.