Patent Description:
A tourniquet is a well known device for suppressing hemorrhaging. A strap, e.g. a bandage, twisted tight by an improvised implement such as a stick is traditionally used to apply pressure onto an artery and to therefore stop the flow of blood through a limb.

An online brochure for Delfi Medical Elastic Cuff (at http://www. delfimedical. com/wp-content/uploads/<NUM>/<NUM>/EasifitCuffBrochure-Sept2013. pdf) describes variable contour and cylindrical tourniquet cuffs. These cuffs are for use by different sized wound victims, and include a strap wrappable around a wounded limb to provide a desired hemorrhage suppressing force which is configured with first and second sections having different widths. The second (i.e., port) section is a circumferential pressure-applying section which is narrower and longer than the first section, and is adapted to be wrapped around the wounded limb to apply circumferential pressure thereto and suppress hemorrhaging.

<CIT> describes a pneumatic tourniquet having an inflatable strap, a compressed gas container and a flow control unit attached to the inflatable strap. The flow control unit, when triggered, is configured to selectively supply a dose of pressurized gas discharged from the gas container to an internal strap cavity, to achieve a predetermined cavity pressure for applying a required hemorrhage suppressing force onto a limb.

As described in "<NPL>, a study found that a wide tourniquet cuff is less painful than a narrow cuff if inflated at lower pressures and at these lower pressures it is still effective at occluding blood flow.

<CIT> describes methods of manufacturing and inflating an elongated bladder of a tourniquet cuff that may be secured around the limb of a patient. The method includes sealing together side edges of layers of material to form the bladder, and stiffening the cuff with a stiffener for compressing the portion of the bladder underlying the stiffener inwardly toward the limb while preventing two layers of the cuff from contacting each other at a location adjacent to an edge of the cuff to thus provide a continuous pneumatic passageway in the bladder between the overlying stiffener and the sealed edge for distributing inflating gas through the passageway along the length of the bladder.

<CIT> describes a tourniquet cuff with identification apparatus including an outer strip; an inner strip positioned against the outer strip; a gas-tight seal joining the inner strip to the outer strip to form a cuff having a physical characteristic wherein the cuff includes an inflatable bladder of a predetermined length greater than the circumference of a limb at a selected location; and a cuff connector carried on the cuff and communicating pneumatically with the bladder for releasably connecting to a tourniquet instrument to establish a gas-tight passageway between the bladder and the instrument.

<CIT> describes an automated pressure regulator that can be integrated into a portable battlefield tourniquet. The automated pressure regulator includes an inlet port configured to engage a pressurized gas bottle to receive pressurized gas therefrom, and an outlet port that is sealably coupled to an inflatable bladder. The automated pressure regulator finds application in devices where rapid inflation is important and where monitoring of the pressure in the internal bladder is desirable so as to maintain an acceptable (minimum) pressure, but where user observation is not necessarily practicable because of the surrounding environmental conditions.

<CIT> describes a tourniquet system for rapid automatic application of adequate pressure to stem bleeding of an injured limb while minimizing tissue damage due to excessive pressure. Pressure is supplied to the limb by inflation of a tourniquet cuff with compressed gas. The invention also relates to a method of controlling bleeding from a limb using the tourniquet system.

<CIT>describes a pneumatic tourniquet end for preventing the flow of blood through bodily extremities. More specifically, this patent describes a lightweight, portable, inflatable tourniquet having a self-contained source of pneumatic pressure and adapted to be readily self-applied.

<CIT> describes a self-regulating tourniquet having a pressure source, a pressure applicator apparatus associated with the pressure source and operative to apply pressure therefrom to a limb and a pressure regulator associated with the pressure source and the pressure applicator operative to restrict the pressure transferred from the pressure source to the limb to a designated maximum pressure applied to the limb. The pressure source and the pressure applicator may be separate modules that are adapted to be engaged by connecting means and establish gas passage from the pressure source to the pressure applicator.

<CIT>describes a disposable plastic tourniquet which includes an inflatable elongated envelope formed from three layers of vinyl plastic, of which one layer extends from one end of the envelope to form a long tongue. A sheet of stiffening material is positioned between two of the layers of vinyl to increase the contact surface, and a strip of pressure sensitive tape extends from each side of the envelope to engage the tongue and lock the tourniquet in position on the patient.

<CIT> describes a pneumatic tourniquet adapted for self-application by an injured person in a military or emergency situation to stop arterial blood loss in an injured arm or leg. The tourniquet includes a bladder having a width dimension and having a length dimension greater than the circumference of an injured limb of a subject at a selected location; and clamp means for securing the bladder around the limb at the selected location and adapted for sealing the bladder across the bladder width to establish an inflatable portion of the bladder to be the portion of the bladder that encircles the injured limb at the selected location.

Other manually applied tourniquets using a force applier such as a ratchet or a windlass are able to stop the loss of blood from an injured arm within <NUM>-<NUM> seconds. However, a significantly larger force on the order of <NUM>-<NUM> N needs to be applied for a significantly longer duration, in order to suppress the hemorrhaging of the femoral artery, due to the increased depth thereof with respect to the skin surface relative to that of the brachial artery, and due to the greater dimensions of the thigh relative to the arm. The actual force needed to suppress hemorrhaging is dependent upon the thickness of the limb, the depth of the artery within the limb and the width of the strap transmitting the applied force to the wounded artery. The width of the strap is generally limited in order to reduce the magnitude of the manually applied force needed to suppress hemorrhaging. Damage to soft tissue, muscles, nerves and bones within the wounded limb is liable to result, particularly due to the narrow dimension of the strap of approximately <NUM> that cuts into the skin, if an excessive force is applied.

It would be desirable to provide a pneumatically applied tourniquet having a relatively wide strap that is able to apply a uniform pressure onto a wounded limb despite the sufficiently high hemorrhage suppressing force being applied thereby and that is therefore unpainful to soft tissue.

Pneumatic tourniquets are commonly used in extremity surgery to achieve a nearly bloodless surgery while being able to apply a relatively high hemorrhage suppressing force onto a wounded limb. Such prior art pneumatic tourniquets comprise an inflatable cuff, which is a type of strap configured with a rubber bladder positioned within a plastic or fabric covering. Connective tubing is used to connect the cuff to a pressure device that includes an air compressor, buttons for setting the pressure, a digital display of the pressure setting, and a timer. The pressure device is powered by electricity, and is therefore connected to a wall outlet. The apparatus associated with these prior art pneumatic tourniquets is accordingly stationary, and is not useful to medics that need to treat wound victims at remote locations. Also, the wide straps used in a hospital setting, which may have a width on the order of <NUM>, are bulky, and are not readily transportable in a compact pouch so as to be useful to medics.

Disadvantages of other prior art pneumatic tourniquets include the lack of protection of the source of pressurized gas needed to inflate a strap, and therefore the unsuitability for use in a battlefield environment, and the inability to use the source of pressurized gas for more than one hemorrhage suppression operation.

Wounded victims are prone to ischemia within limb tissues during prolonged use of a tourniquet, as a result of the stop of blood flow distal to the tourniquet. The level of the ischemic changes is dependent on the duration during which the limb has been obstructed. These symptoms may be reversible if the pressure applied by the tourniquet is for a short term of less than two hours, or is periodically released for short intervals of a few minutes while allowing some bleeding to recur. However, medics are discouraged in releasing the pressure before the victim is brought to a hospital, such as by deflating the pressure within the strap if a pneumatic tourniquet is employed, due the occurrence of incremental exsanguination which can lead to death. After deflation of a pneumatic tourniquet, products of acidosis, lactate, toxic metabolites and oxygen free radicals are introduced into the blood system and cause complications such as systemic metabolic changes and reperfusion syndrome that might lead to cardiac arrest.

Moreover, if a pneumatic tourniquet were temporarily deflated in a pre-hospital setting, the stored pressurized gas would become depleted while the strap interior is exposed to atmospheric air, and therefore the pneumatic tourniquet could not be used after being deflated.

It is an object of the present invention to provide a pneumatic tourniquet for use by both a medic and an unexperienced responder in an emergency pre-hospital setting, in order to inflate a strap applying a hemorrhage suppressing force to a predetermined pressure.

It is an additional object of the present invention to provide a pneumatic tourniquet that is not injurious to both adult and pediatric wounded victims while the inflated strap is being applied.

It is an additional object of the present invention to provide a compact, reliable and user friendly pneumatic tourniquet that can be readily deployed at remote locations.

It is yet an additional object of the present invention to provide a pneumatic tourniquet that is adapted for use by a physician to temporarily deflate the strap, if need be.

It is yet an additional object of the present invention to provide a pneumatic tourniquet having a flow control unit that can be used for a plurality of hemorrhage suppression operations.

It is yet an additional object of the present invention to provide a pneumatic tourniquet that reduces the consumption of pressurized gas used for each hemorrhage suppression operation.

The invention is limited to the subject-matter as defined in the claims. Other described aspects are included for illustrative purposes only.

According to the present invention, there is provided a pneumatic tourniquet as set out in claim <NUM> below. The tourniquet may be used for different sized wound victims.

In one embodiment, the pneumatic tourniquet further comprises a constricting device adapted to receive a free end of said strap in such a way that said free end is unrestrainably displaceable within said constricting device until being clamped thereby when said strap is sufficiently tensioned to transmit the hemorrhage suppressing force. The constricting device may comprise a housing member and a rocker rotatably mounted onto, and within, said housing member by a longitudinally extending axle, said rocker being configured to be angularly displaced about said axle until a surface of said rocker is set in clamping relation with a clamping edge of said housing member while said strap is interposed between said rocker surface and said clamping edge, in response to a force applied by the wounded limb onto said rocker when said strap is sufficiently tensioned.

In one aspect, the pneumatic tourniquet further comprises a sealing element, wherein a clamping force applied by said rocker surface and said clamping edge onto said sealing element prevents flow of the pressurized gas from a pressure applying section of said strap which is wrapped around the wounded limb to said free end, allowing said strap free end to be considerably thinner than said pressure applying section.

In one aspect, the sealing element is provided internally within the strap, the strap being configured with an inner layer, an outer layer, and an intermediate sealant layer that are interconnected.

In one aspect, the sealing element is external to the strap.

A user-friendly gas flow control assembly of a pneumatic tourniquet comprises a casing which contains a housing with which a gas cartridge filled with pressurized gas and normally sealed by an occluding element is coupleable, a longitudinally displaceable force transmitting element, and an outlet port; a pivotable activation handle configured with a wide-area, substantially planar user-manipulatable surface; and a structure provided with said casing which cooperates with said activation handle to define an axis of rotation of said activation handle, wherein, upon pivoted displacement of said activation handle about its axis of rotation, an activation force is transmitted that drivingly contacts said force transmitting element to forcefully contact and open at least a portion of said occluding element, causing the pressurized gas to be discharged from said gas cartridge and flow via said outlet port to an interior of an inflatable strap which is wrappable around a wounded limb to provide a desired hemorrhage suppressing force.

In one aspect, the occluding element is a puncturable cover and the force transmitting element is a puncture pin that terminates with a pointed end that is drivable to an inwardly displaced position at which the pointed end punctures the puncturable cover.

In one aspect, the force transmitting element is an activation piston configured to cooperate with a valve stem associated with the gas cartridge.

In one aspect, the structure provided with said casing which cooperates with said activation handle to define the axis of rotation is a laterally extending beam which is rotatably mounted in corresponding seats provided with said casing to define the axis of rotation of said activation handle. A cam which is fixedly connected to said beam may be in drivable proximity with said force transmitting element.

A flow control unit (such as a pressure regulating unit) which comprises a housing member configured with an inlet for receiving pressurized gas upon demand and with an internal cavity; a hollow tube having an outer diameter of less than <NUM> which is in fluid communication with said inlet; an intermediately bored piston connected to, and which has an outer diameter significantly greater than, said tube, said piston being axially and sealingly displaceable within said internal cavity to define at a distal end thereof a supply chamber in fluid communication with atmospheric air and, at a proximal end thereof, a regulating chamber which is in fluid communication with said inlet via said tube; and a fixed sealing element, wherein, following flow of the pressurized gas into said regulating chamber, said piston is caused to be distally displaced by a pressure differential between the pressure in said regulating chamber and in said supply chamber until a distal end of said tube is occluded by said sealing element, to prevent additional inflow of the pressurized gas.

A pneumatic tourniquet comprises an inflatable strap wrappable around a wounded limb to provide a desired hemorrhage suppressing force; and a pressure regulating unit configured with an inlet for receiving pressurized gas upon demand; a piston axially and sealingly displaceable within an internal cavity to define at a distal end thereof a supply chamber in fluid communication with atmospheric air and, at a proximal end thereof, a regulating chamber which is in fluid communication with said inlet and with an interior of said strap; and a manual pressure release initiator, which, when displaced, provides a clearance that is in fluid communication with said regulating chamber and with atmospheric air to selectively reduce the pressure of the fluid within said strap interior while preventing additional inflow of the pressurized gas to said regulating chamber.

A puncture mitigating connection section for connecting an inflatable strap to a gas flow control assembly casing comprises a flexible inlet port protruding through an external layer of an inflatable strap and having a central passageway which is in fluid communication with an interior of the strap, wherein said inlet port is coupleable with a discharge port of a gas flow control assembly through which pressurized gas for inflating the strap is dischargeable; and a plurality of fastening means protruding from the external layer of the strap and separated from said inlet port, wherein each of said fastening means is coupleable with a corresponding fixed element associated with a casing of the gas flow control assembly.

In one aspect, the plurality of fastening means are integrally formed with a rigid plate positioned within the strap interior and attached to the external strap layer and formed with an aperture through which the inlet port protrudes.

In one aspect, the rigid plate is attached to a semi-rigid sealing layer adapted to provide added protection against efflux of the pressurized gas from the connection section and a mounting element of the inlet port is attached to said semi-rigid sealing layer.

As referred to herein, "longitudinally" means along a direction parallel to the axis of a tubular gas cartridge, when coupled with the puncture unit housing. "Lateral" means in a direction substantially perpendicular to the longitudinal direction. "Transversal" means in a direction at an angle to the longitudinal direction which is not necessarily the lateral direction. "Proximal" means in a direction towards a user accessible element of the tourniquet, such as the manual pressure release initiator or an unattached edge of the activation handle distant from its axis of rotation. "Distal" means in a direction opposite to the proximal direction. Other directional terms, such as "top", "above" and "below" refer to an orientation when the tourniquet is disposed on top of a horizontal surface, although the tourniquet may be disposed at any other desired orientation.

The compact pneumatic tourniquet of the present invention is used primarily, but not necessarily, in emergency settings, such as following a motor vehicle crash, an explosion, and a stabbing incident or on the battlefield in an attempt to stop extremity bleeding and death due to blood loss. Pressure is applied circumferentially around a portion of the wounded limb, after the strap is inflated to a predetermined pressure, causing the blood vessels to which the pressure is applied to become temporarily occluded.

By virtue of its user-friendly configuration, the tourniquet is easily activated by all users, including paramedics, unexperienced responders located unexpectedly at an emergency setting and even the wounded victim, to initiate a hemorrhage suppression operation and the strap is easily wrapped around the wounded limb and tensioned.

The unique configuration of the tourniquet, as will be described hereinafter, dramatically reduces the complications normally associated with the prolonged use of a tourniquet, and injury to skin and subcutaneous tissues as a result of excessive pressure applied to pediatric victims.

Since the pressurized gas for use by the pneumatic tourniquet is supplied internally within the casing of a gas flow control assembly, generally by means of a gas cartridge, and not externally to the casing by electrically operated gas transfer equipment as practiced by the prior art, the compact tourniquet of the present invention lacks any electrical or electronic components, and can advantageously be used in wet or muddy environments. Of course in some embodiments, a well-sealed electronic module, such as one comprising a GPS component for locating a subject or sensors for determining some of the subject's real-time physiological characteristics, similar to an electronic module provided to a diver, may be added.

<FIG> and <FIG> illustrate an embodiment of pneumatic tourniquet <NUM>. Pneumatic tourniquet <NUM> comprises gas flow control assembly <NUM>, constricting device <NUM> pivotally connected to gas flow control assembly <NUM>, and inflatable strap <NUM> which is connected to gas flow control assembly <NUM> and is selectively clamped by constricting device <NUM>.

inflatable strap <NUM> may be configured with three layers <NUM>-<NUM> of substantially equal lengths and widths. Inner layer <NUM> is made of a flexible tear resistant material. Outer layer <NUM>, which is exposed to the underlying terrain often having sharp objects such as thorns and broken glass, is made of a flexible and puncture resistant material such as silicone elastomer or a fabric made of a flexible material, e.g. nylon or polyester, and sealed with a puncture resistant material layer, e.g. polyurethane. The intermediate layer <NUM> is made of a sealant such as polyurethane.

Gas flow control assembly <NUM> is configured with a casing, e.g. a casing having an upper section <NUM> and a lower section <NUM> according to the illustrated orientation to form a curved proximal user-accessible surface. Upper casing section <NUM> and lower casing section <NUM> may be coupled together by a plurality of spaced fasteners <NUM>, e.g. threaded fasteners. Two longitudinally spaced arms <NUM> and <NUM> may extend downwardly from the same side of lower casing section <NUM>, and each terminates with a corresponding arcuate protruding seat <NUM>. The two seats <NUM> face each other.

Within gas flow control assembly <NUM> are mounted a replaceable gas cartridge <NUM>, puncture unit housing <NUM> within which a metallic cover normally sealing gas cartridge <NUM> is punctured in order to enable pressurized gas, e.g. carbon dioxide or nitrogen, to be discharged from the gas cartridge, a pressure regulating unit <NUM> for controlling the pressure of gas discharged into the interior of inflatable strap <NUM>, and manual pressure release initiator <NUM> operatively connected to pressure regulating unit <NUM> for selectively deflating strap <NUM> while ensuring that the remaining pressurized gas within gas cartridge <NUM> will not be discharged. Manual pressure release initiator <NUM> may protrude from the curved proximal surface of the casing.

Gas cartridge <NUM> may be supplied with carbon dioxide, nitrogen, a noble gas or a refrigerant gas. The gas, which is compressed at a pressure of <NUM>-<NUM> bar at <NUM> and approximately <NUM> bar at -<NUM>, is replaceable upon removing cartridge cover <NUM>. Cover <NUM> may have, for example, a width of approximately one-half the casing width, a length of approximately a fourth of the casing length, and a height approximately equal to the total thickness of upper casing section <NUM> and lower casing section <NUM>, or any suitable dimensions. Cartridge cover <NUM> may be releasably secured to the casing by means of one or more magnets <NUM>, which are attached to lower casing section <NUM>.

Alternatively, gas flow control assembly <NUM> may be configured without a pressure regulating unit or without a puncture unit housing. When the gas flow control assembly is configured without a puncture unit housing, another type of force transmitting element, such as element <NUM> shown in <FIG>, may be selectively driven to forcefully contact and open at least a portion of an occluding element normally sealing gas cartridge <NUM>, to facilitate flow of the pressurized gas from the gas cartridge and into to the interior of inflatable strap <NUM>.

Alternatively, the gas flow control assembly is provided with an irreplaceable gas cartridge and is accordingly configured without a cartridge cover.

A thin and wide-area activation handle <NUM> for initiating inflation of strap <NUM> is pivotally connected to a distal region of the casing of gas flow control assembly <NUM>. Activation handle <NUM> is rendered to be of a user-friendly wide area when its width is more than <NUM>% of the width of gas flow control assembly <NUM>. Activation handle <NUM> normally overlies a recess <NUM> formed in upper casing section <NUM> by a small interspace sufficient to insert a portion of a finger therein, e.g. <NUM>, and to pivotally raise handle <NUM>. The thickness of activation handle <NUM> is generally uniform; however, it may increase gradually, for example from <NUM> in the region contacted by the fingers to maximize the finger clearance to <NUM> in the region of the pivot axis, so as to increase the overall structural strength of the activation handle. Activation handle <NUM> is substantially planar to reduce the amount of material needed, although it may be somewhat curved, while of substantially high structural strength in order to be able to transmit an activation force, as will be described hereinafter.

In one embodiment, recess <NUM> extends distally to timer device <NUM>, e.g. a digital timer device, adapted to indicate the initiation of a hemorrhage suppression operation, which is housed in the half of upper casing section <NUM> not occupied by cartridge cover <NUM> being distally to the curved proximal surface.

Constricting device <NUM> for clamping inflatable strap <NUM> when sufficiently tensioned comprises housing member <NUM> and rocker <NUM> rotatably mounted onto, and within, housing member <NUM> by axle <NUM>.

Housing member <NUM> has a thickened terminal wall <NUM>, which may be planar and rectangular, and an outer wall <NUM> and two longitudinally spaced side walls <NUM> that extend downwardly from upper wall <NUM> to a height below the lower surface of terminal wall <NUM> to define a protruding portion <NUM>, with respect to the illustrated orientation. The lower edge <NUM> of outer wall <NUM> constitutes a clamping edge. An aperture <NUM> is bored in each side wall <NUM>, so that the two apertures <NUM> are aligned. A curved element <NUM> extends downwardly from the inner edge <NUM> of upper wall <NUM>, and terminates with two hinge elements <NUM> longitudinally extending in opposite directions that are received in corresponding seats <NUM>, allowing housing member <NUM> to rotate about the axis coinciding with seats <NUM>.

Rocker <NUM> has a planar surface <NUM>, which may be rectangular, and two longitudinally spaced side walls <NUM> that upwardly extend from surface <NUM> and that may be upwardly curved. Each side wall <NUM> may have a short portion <NUM> that laterally projects from the curved portion and whose upper edge is coplanar with surface <NUM>. Short inner <NUM> and outer <NUM> legs extending longitudinally between the two side walls <NUM> may extend downwardly from surface <NUM>. The longitudinal spacing between side walls <NUM> is less than that of side walls <NUM> of housing member <NUM>. An aperture <NUM> is bored in each side wall <NUM>, preferably in a region closer to the corresponding short portion <NUM>, such that the two apertures <NUM> are aligned. Axle <NUM> is adapted to be received within apertures <NUM> and <NUM>, to allow rocker <NUM> to swing thereabout. An outer wall <NUM>, i.e. facing away from arms <NUM> and <NUM>, longitudinally extends between the two short portions <NUM> and upwardly extends from surface <NUM> to a height significantly less than that of side walls <NUM>.

<FIG> illustrates a top view of inflatable strap <NUM> when flattened out. Strap <NUM> may be configured with two integral sections <NUM> and <NUM> of different widths. Section <NUM> of uniform width A, e.g. <NUM>, is elongated, and is adapted to be wrapped around a wounded limb in order to apply circumferential pressure and to suppress hemorrhaging. Section <NUM> of maximum width B greater than width A, e.g. <NUM>, which is connectable to the casing of the gas flow control assembly for increased connection strength, may be configured with a curved, e.g. elliptical, periphery. By providing a strap with a relatively narrow pressure applying section, the constricting device through which strap <NUM> is freely displaceable until being restrained may advantageously be narrow as well, to achieve a compact device. The short terminal end <NUM> of strap <NUM> being opposite to connection section <NUM>, which is included in the free end of the strap that is pulled during a tensioning operation, may have a width that is slightly greater than A, e.g. <NUM>, in order to prevent retraction of the free end in an opposite direction through the constricting device.

As opposed to manually applied tourniquets which are narrow, generally having a strap width of up to <NUM> due to the difficulty in applying the required hemorrhage suppressing force, the pneumatic tourniquet of the present invention is capable of achieving sufficiently high pressures for applying a hemorrhage suppressing force to even very large diameter limbs. A strap <NUM> configured with two integral sections <NUM> and <NUM> of different widths has significant clinical advantages in that a hemorrhage suppressing force will not be transmitted entirely by relatively narrow section <NUM>. Wrapping a relatively wide strap section <NUM>, e.g. of <NUM>, around the limb or at least most of the limb leads to even distribution of the pressure applied onto the surface of the limb and helps to diminish pain and local damage, advantages which are of much importance with respect to subjects having a small limb diameter, such as in pediatric patients. At the same time, a relatively high hemorrhage suppressing force may be transmitted via relatively long and narrow section <NUM> to adult victims having relatively large-diameter limbs without undue pain and damage to tissue.

In one embodiment, the two sections <NUM> and <NUM> are made of different materials that have a different degree of flexibility. The relative width of sections <NUM> and <NUM> accordingly may change after strap <NUM> is inflated. For example sections <NUM> and <NUM> may have the same width prior to the inflation of the strap; however following inflation, section <NUM> becomes thinner and longer than section <NUM>.

It will be appreciated that an inflatable strap may have a uniform width.

In one embodiment, the strap provided with sections <NUM> and <NUM> of different widths may be uninflatable. Sections <NUM> and <NUM> may be integrally formed with the uninflatable strap, or alternatively may be connected together, e.g. releasably connected together, by various means well known to those skilled in the art such as adhesion, sewing, fusion, buttons, and hook-and-loop fasteners.

Connection section <NUM>, as shown in <FIG>, is internally provided with a relatively rigid attachment plate <NUM> adapted for attachment to the gas flow control assembly casing, in addition to outer layer <NUM>, intermediate sealant layer <NUM> and inner layer <NUM> of the inflatable strap. Inner layer <NUM> is adapted to be in contact with a wounded limb <NUM>. internal attachment plate <NUM>, which may be made of a relatively rigid plastic such as polypropylene or high-density polyethylene, is connected between outer layer <NUM> and sealant layer <NUM>, such as by welding. The three layers <NUM>-<NUM> may be welded together by a welding line <NUM> that extends lengthwise along the entire corresponding widthwise edge of the inflatable strap that includes both pressure applying section <NUM> and connection section <NUM>.

As further shown in <FIG>, a plurality of separated snapping fasteners <NUM>, or any other suitable type of fasteners such as screws or clips, connected to the attachment plate protrude outwardly within connection section <NUM> from the outer strap layer. Also protruding outwardly from the outer strap layer is a tubular port <NUM> for the passage therethrough of pressurized gas into the strap interior, which is positioned generally centrally with respect to the plurality of fasteners <NUM>.

<FIG> and <FIG> illustrate tourniquet <NUM> from below when constricting device <NUM> is set to an opened position suitable for cooperating in performance of a hemorrhage suppression operation and to a closed pivoted position, respectively, suitable to be compactly stored in a pouch in preparation to being dispatched during an emergency setting to assist a wounded victim. When constricting device <NUM> is set to the pivoted position, the hinge elements rotate approximate <NUM> degrees until terminal wall <NUM> of the housing member is substantially parallel to the underside surface <NUM> of the casing of gas flow control assembly <NUM>.

When the strap is uninflatable, a small member from which downwardly extend arms <NUM> and <NUM> (<FIG>) may be secured to the strap in lieu of the casing of the gas flow control assembly.

Strap <NUM> shown in <FIG> may also be compactly stored, for example after being wrapped about itself, in the same or a different pouch as the pivoted constricting device and gas flow control assembly.

As shown in <FIG> and <FIG>, partially illustrated connection section <NUM> of the inflatable strap is positioned in abutting relation with casing underside surface <NUM> by the plurality of snapping fasteners <NUM>, which are attached to a portion of lower casing section <NUM> located below the partially illustrated gas cartridge <NUM>, when coupled to puncture unit housing <NUM>.

Some elements that enable the flow of pressurized gas into the interior <NUM> of the inflated strap <NUM> are illustrated in <FIG>, <FIG>, <FIG> and <FIG>. The flow of pressurized gas discharged from the gas cartridge is directed to the interior <NUM> of the inflatable strap by means of centrally bored port <NUM>. Port <NUM> may be part of an element that is coupleable, e.g. releasably coupleable, with gas flow control assembly <NUM> prior to performance of a hemorrhage suppression operation. Such an element may comprise an integral abutment member <NUM> having a diameter, or maximum width, significantly greater than that of port <NUM>. Tubular port <NUM> may be factory-secured to attachment plate <NUM> via an aperture formed in attachment plate <NUM> and in outer layer <NUM> and intermediate layer <NUM> of the inflatable strap, such that abutment member <NUM> is brought in pressing relation with attachment plate <NUM>.

Port <NUM> may be coupled to pressure regulating unit <NUM> via a conical nipple <NUM> extending downwardly from a discharge conduit <NUM> of the pressure regulating unit by a simple pressing motion transmitted through coupling section <NUM>. When coupling section <NUM> is attached to the casing underside surface, pressurized gas discharged from the gas cartridge will be directed via tube <NUM> of pressure regulating unit <NUM>, discharge conduit <NUM>, nipple <NUM> and port <NUM> to the interior <NUM> of the inflatable strap.

While pressurized gas is introduced to the common interior <NUM> of pressure applying section <NUM> and coupling section <NUM>, inner layer <NUM> becomes separated from intermediate sealing layer <NUM> as the pressurize within interior <NUM> rises.

Alternatively, connection section <NUM> shown in <FIG> may be employed.

<FIG> illustrates pneumatic tourniquet <NUM> when deployed during a hemorrhage suppression operation. To ensure a speedy hemorrhage suppression operation, free end <NUM>' of the strap is pre-fed through constricting device <NUM> while the tourniquet is stored. During an emergency setting, tourniquet <NUM> is first removed from its pouch and constricting device <NUM> is positioned at a selected region of wounded limb <NUM> relative to the wound site. Pressure applying section <NUM> is then wrapped around limb <NUM> until connection section <NUM> is attached to gas flow control assembly casing <NUM> while the latter remains in abutment with limb <NUM>. Upon freely pulling on free end <NUM>' of the strap by applying a force T in a direction away from constricting device <NUM>, pressure applying section <NUM> becomes sufficiently tensioned to enable performance of the subsequent hemorrhage suppression operation after the discharge of pressurized gas from the gas cartridge has been initiated.

As shown in <FIG>, strap <NUM> is positioned in movable contact with upper strap-engageable surface <NUM> of rocker <NUM> and below axle <NUM> while being fed through constricting device <NUM>, for example at a factory or by a medical practitioner when the tourniquet is being deployed. When strap <NUM> is sufficiently tensioned while wrapped around the wounded limb, the limb applies a force to inner wall <NUM> of each side wall of rocker <NUM>. This applied force causes rocker <NUM> to rotate about axle <NUM>, in a counterclockwise direction according to the illustrated orientation, until the outer rocker wall <NUM> is brought in clamping relation with the clamping edge <NUM> of the outer wall <NUM> of housing member <NUM> while strap <NUM> is interposed between outer rocker wall <NUM> and housing member outer wall <NUM>. The angular displacement of rocker <NUM> may also be facilitated by spacing axle <NUM> away from the vertical centerline of each side wall <NUM>, to provide eccentric motion. At this clamping relation, the free end of strap <NUM> can no longer be freely pulled, but rather is clamped.

Manual pressure release initiator <NUM>, whose operation will be described hereinafter, may be used to disengage the strap from clamping edge <NUM> by reducing the pressure within the strap interior and allowing the strap to be once again freely displaceable, or to release the pressure gradually before removing the tourniquet.

Referring back to <FIG>, the clamping relation established between the outer rocker wall and the outer housing member wall advantageously also allows the strap free end <NUM>' to be considerably thinner than pressure applying section <NUM> of the strap. When pressurized gas at a predetermined pressure is introduced into the interior of the strap, the strap becomes inflated and a radial hemorrhage suppressing force S is applied to limb <NUM>. Without cooperation with constricting device <NUM>, an inflated free end <NUM>', which may have a length on the order of <NUM>, is liable to be bothersome, and times even injurious, to the wounded victim and to the health practitioner attempting to assist the victim. The outer rocker wall and the outer housing member wall, when a clamping relation is established at the clamping edge, both apply a clamping force to the intermediate sealant layer of the strap, thus preventing passage of the pressurized gas from pressure applying section <NUM> beyond the clamping edge to free end <NUM>'. The intermediate sealant layer which is located close to the outer layer also assists in preventing seepage of the pressurized gas outwardly from the strap interior to the atmosphere.

Reference is now made to <FIG>, which illustrate the apparatus adapted to cooperate with puncture unit housing <NUM> in order to initiate discharge of pressurized gas from gas cartridge <NUM>. The discharged gas flows via interconnecting structure <NUM> from puncture unit housing <NUM> to pressure regulating unit <NUM>.

As shown in <FIG>, a puncture pin <NUM> normally protruding outwardly from puncture unit housing <NUM> when in a retracted position is subsequently axially displaceable within bore <NUM> formed within puncture unit housing <NUM>.

Puncture pin <NUM> is configured with an elongated shaft <NUM> that terminates with pointed end <NUM> which is adapted to puncture the metallic cover <NUM> of gas cartridge <NUM>, after the latter has been inserted to a substantially fullest extent within puncture unit housing <NUM> via an opening at an end thereof opposite to puncture pin <NUM> by means of threaded engagement <NUM>. Puncture pin <NUM> also has a large sized head element <NUM>, which is contacted when a driving force is applied thereto by the activation handle and is caused to be displaced to an inwardly displaced position. Displacement of puncture pin <NUM> at a sufficiently high force to the inwardly displaced position causes pointed end <NUM> to puncture metallic cover <NUM>, resulting in discharge of pressurized gas from gas cartridge <NUM>. The discharged gas flows through bore <NUM> and conduit <NUM>, which is in fluid communication with bore <NUM> and passes through interconnecting structure <NUM> from puncture unit housing <NUM> to housing <NUM> of pressure regulating unit <NUM>. Sealing elements <NUM> and <NUM>, e.g. O-rings, at the two ends of bore <NUM>, respectively, prevent gas seepage.

Head element <NUM> limits the inward displacement of puncture pin <NUM> upon contacting a surface of the puncture unit housing <NUM> when set to the displaced position. Puncture pin <NUM> may be returned to the retracted position by the pressure of the discharged gas when the force applied to the activation handle is released.

Alternatively, as shown in <FIG>, a helical spring <NUM> surrounding the puncture pin shaft, is biased to assist in returning the puncture pin to the retracted position after the force applied by the activation handle has been released. Helical spring <NUM> may be compressed by head element <NUM>, for example simultaneously with the pivoting of the activation handle and the puncturing of the metallic cover. When the force applied to the activation handle is released, the stored spring energy is also released, causing the puncture pin to be retracted. The retracted head element may consequently apply a force that causes the activation handle to pivot in an opposite direction to a non-pivoted position.

<FIG> illustrates a user friendly activation handle <NUM> when separated from the casing of the gas flow control assembly. Activation handle <NUM> comprises a thin and wide-area, substantially planar user-manipulatable surface <NUM>, which may have an arcuate distal edge in order to avoid interference with the casing when being pivoted. User-manipulatable surface <NUM> is provided with two opposed sidewalls <NUM> adapted to be contiguous with a corresponding upper casing section sidewall when activation handle <NUM> is in an unpivoted position and that extend along the entire length of surface <NUM>, or along only a distal portion of surface <NUM> as shown in <FIG> and <FIG>. An arcuate extension <NUM> is located below, and curves inwardly at a portion thereof with respect to, the distal region of the corresponding sidewall. A planar surface <NUM> substantially perpendicular to user-manipulatable surface <NUM> is in contact inwardly with respect to an extreme distal portion of a corresponding pair of a sidewall <NUM> and extension <NUM>. A laterally extending beam <NUM> extends between the two planar surfaces <NUM>, and has a curved surface which is rotatably mounted in two laterally spaced, thin concave seats <NUM> provided with lower section <NUM> (<FIG>), to define the axis of rotation of activation handle <NUM>.

Protruding downwardly from beam <NUM> is a cam <NUM>, e.g. elliptically shaped, which is in drivable proximity to head element <NUM> of the puncture pin, as shown in <FIG>. One or more stoppers <NUM>, e.g. triangularly shaped, protrude distally from beam <NUM> in order to limit the pivotal displacement of activation handle <NUM> by contacting a region of the gas flow control assembly casing.

This configuration of activation handle <NUM> advantageously provides a mechanical advantage in terms of the ratio of the longitudinal length L of user-manipulatable surface <NUM> from line <NUM> passing through its axis of rotation which coincides with beam <NUM> to the longitudinal length M of cam <NUM> from the axis of rotation, which ranges from <NUM>-<NUM>:<NUM>, for example <NUM>:<NUM>. With this mechanical advantage, an-average magnitude force applied while raising user-manipulatable surface <NUM> will output an amplified driving force applied to the puncture pin on the order of <NUM>, which is sufficient to puncture the metallic cover <NUM> of gas cartridge <NUM>.

When activation handle <NUM> is pivoted about its axis of rotation as shown in <FIG> and <FIG>, cam <NUM> attached thereto is also pivoted in a similar direction. At this pivoted position, the curved periphery of cam <NUM> slidingly and drivingly contacts head element <NUM> to the inwardly displaced position so that the pointed end of the puncture pin punctures the metallic cover. A curved recess <NUM> formed in the gas flow control assembly casing facilitates the pivoted displacement of arcuate extension <NUM> without interference. The actions are reversed when activation handle <NUM> is pivoted in an opposite direction.

The structure and operation of pressure regulating unit <NUM> will now be described, with reference to <FIG>, <FIG>, <FIG> and <FIG>.

As shown in <FIG>, pressure regulating unit <NUM> has a housing <NUM> configured with an internal cavity within which piston <NUM> fitted with O-ring <NUM>, or any other suitable sealing element, is axially and differentially displaceable to define a spring-based supply chamber <NUM> and a separated regulating chamber <NUM>. Supply chamber <NUM> is supplied with atmospheric air via opening <NUM> formed in housing <NUM>.

A narrow hollow tube <NUM> connected to piston <NUM>, such as by adhesive material <NUM>, or alternatively by a fastener such as a threaded connection, passes through the entire thickness of piston <NUM> and is in fluid communication with regulating chamber <NUM>. Tube <NUM> is adapted to receive pressurized gas discharged from the gas cartridge via conduit <NUM> and to transfer the gas to regulating chamber <NUM>. Helical spring <NUM>, which may be attached to the distal edge <NUM> of supply chamber <NUM>, surrounds tube <NUM>, and is used to control the pressure within the strap interior.

Cap <NUM>, which may be metallic and threadedly engageable with housing <NUM> at narrow end <NUM> thereof, is used to direct the pressurized gas to tube <NUM>. A planar sealing element <NUM>, e.g. made of EPDM rubber, is attached to the proximal end of cap <NUM>, and is also attached to an annular flanged element <NUM>, e.g. planar, configured to carry an elongated annular element <NUM> within which tube <NUM> is receivable and axially displaceable. Annular element <NUM> has two openings <NUM>, which may be diametrically opposite to each other. One of the openings <NUM> is alignable with conduit <NUM> when cap <NUM> is engaged with housing <NUM> to a fullest extent in conjunction with aligning means well known to those skilled in the art. The discharged pressurized gas is non-escapingly flowable from conduit <NUM> to the aligned opening <NUM>, and from the aligned opening to the distal end of tube <NUM>, i.e. close to cap <NUM>, by means of various dedicated passageways, such as passageways of varying diameters and orientations, provided within the annular flanged element <NUM> and elongated element <NUM>. The proximal end of elongated element <NUM> holds O-ring <NUM> constituting additional means for preventing the escape of the pressurized gas.

Three secondary passageways <NUM>, <NUM> and <NUM> formed in shell <NUM>, which is connected to housing <NUM>, are in fluid communication with regulating chamber <NUM>. First passageway <NUM> is used for the flow of the pressurized gas to the strap interior. First passageway <NUM> may be in communication with threadedly engageable socket <NUM>, which is adapted to be engaged, e.g. releasably engaged, with discharge conduit <NUM> illustrated in <FIG> and <FIG>. Manual pressure release initiator <NUM> is in communication with second passageway <NUM>. Pressurized gas, if its pressure rises about a predetermined threshold, is releasable to the atmosphere by means of safety valve <NUM>, the structure of which is well known to those skilled in the art, through third passageway <NUM>. Thus the same pneumatic tourniquet may be used for suppressing hemorrhaging while the victim is treated at the emergency setting, flown to the hospital and treated at the hospital without concern that the pressure of the gas will be excessive.

When the pressurized gas is initially discharged from gas cartridge <NUM>, there is an axial clearance between the distal end of tube <NUM> and sealing element <NUM> since the atmospheric pressure in supply chamber <NUM> is greater than or equal to the pressure in regulating chamber <NUM>, which is devoid of pressurized gas, and spring <NUM> is biased to retain piston at a predetermined spacing from the distal edge <NUM> of supply chamber <NUM>. Thus the pressurized gas is introduced into tube <NUM> and flows to regulating chamber <NUM> via first passageway <NUM>, allowing the pressure within strap interior <NUM> to rise. Eventually, following the flow of pressurized gas into regulating chamber <NUM>, the pressure in regulating chamber <NUM> is greater than the pressure in supply chamber <NUM> and greater than the biasing force of spring <NUM>, and piston <NUM> is forced to be distally displaced. When piston <NUM> is sufficiently distally displaced, the distal end of tube <NUM> is occluded by sealing element <NUM>, preventing additional inflow of pressurized gas. Thus the pressure within strap interior <NUM> is retained at a predetermined level and sufficient pressurized gas remains in gas cartridge <NUM> to enable additional hemorrhage suppression operations and to impart the pneumatic tourniquet with the capability of being a multi-use tourniquet.

As opposed to prior art pressure regulators that rely on precise and expensive machining with a CNC lathe in order to achieve reliable sealing, to provide for example a conical tube configuration with a smooth finish and having an outer diameter of at least <NUM> that is formed integrally with the piston, tube <NUM> advantageously has an outer diameter <NUM> of less than <NUM>. At such a small dimension, tube <NUM> shown in <FIG> can achieve reliable sealing by providing a conical distal end <NUM> produced by inexpensive cutting and without a smooth finish, since mere contact between the distal end and the sealing element that results in only slight depression of the sealing element is sufficient to reliably occlude tube <NUM>. Other advantages of a small-sized tube include the ability of being mechanically connectable to the piston, quick and inexpensive material removal time as the tube is produced from a blank having a diameter substantially equal to that of the tube rather than that of the integral relatively large-sized piston as has been practiced heretofore in the prior art, a simply produced seal, and a low required sealing force in response to using a small-diameter tube.

The operation of manual pressure release initiator <NUM> will now be described with reference to <FIG>, <FIG>, <FIG>, <FIG>.

Manual pressure release initiator <NUM> comprises main rod <NUM> that is axially displaceable within second passageway <NUM> of shell <NUM> and that cooperates with O-ring <NUM> normally fitted within, and of a substantially equal outer diameter as, the second passageway. A secondary rod <NUM> extends proximally from, and below, the proximal end of main rod <NUM>, and terminates with a finger-engageable protuberance <NUM>. A stopper <NUM>, e.g. an oblique stopper, extends proximally from the interface between main rod <NUM> and secondary rod <NUM>, and is used to limit the proximal displacement of manual pressure release initiator <NUM> upon contacting a casing element <NUM>, as shown in <FIG>.

Alternatively, the manual pressure release initiator may comprise a single rod extending distally from protuberance <NUM>.

<FIG> and <FIG> illustrate manual pressure release initiator <NUM> when set to a retracted proximal position. At this retracted position, main rod <NUM> is received within, and engaged with, O-ring <NUM> which is sealingly engaged within second passageway <NUM>, such that the second passageway is occluded in unison by main rod <NUM> and O-ring <NUM> to prevent egress of the pressurized fluid received in regulating chamber <NUM> to the atmosphere.

If the medical practitioner desires to reduce the pressure within the strap interior in order to remove the tourniquet from the victim or to prevent development of ischemia within muscle tissues during prolonged use of the tourniquet, protuberance <NUM> is pushed to cause distal displacement of main rod <NUM> together with O-ring <NUM> engaged therewith. When main rod <NUM> is set to the distal advanced position illustrated in <FIG>, O-ring <NUM> is displaced outwardly from second passageway <NUM> and into regulating chamber <NUM>, producing a radial clearance between main rod <NUM> and the wall of second passageway <NUM>. When main rod <NUM> is distally advanced to a fullest extent, it contacts piston <NUM> and causes the distal end of tube <NUM> to be occluded by sealing element <NUM>. Since the distal end of tube <NUM> is occluded, ingress of pressurized gas into regulating chamber <NUM> is prevented and egress of the fluid received in regulating chamber <NUM> to the atmosphere via the radial clearance around main rod <NUM> commences, to enable reduction in the magnitude of the hemorrhage suppressing force being applied by the fluid pressure within the strap interior. The magnitude of the hemorrhage suppressing force may be periodically reduced during short intervals of e.g. <NUM>-<NUM>.

The degree of pressure reduction may be simply controlled by releasing the force applied to protuberance <NUM>. After the force applied to protuberance <NUM> is released, the pressurized gas remaining in the strap interior flows through first passageway <NUM> and causes piston <NUM> to remain distally advanced. Eventually, main rod <NUM> becomes separated from piston <NUM> and is subsequently proximally displaced within second passageway <NUM>. Main rod <NUM> carries O-ring <NUM> and causes the latter to be received once again within second passageway <NUM> to occlude the radial clearance.

If all the pressurized gas is allowed to escape to the atmosphere, supply chamber <NUM> and regulating chamber <NUM> will achieve equilibrium conditions and the distal end of tube <NUM> will cease to be occluded by sealing element <NUM>. Thus an additional amount of pressurized gas will be delivered to regulating chamber <NUM>.

The ability unknown heretofore of periodically deflating the strap interior at a pre-hospital setting has significant clinical advantages by being able to prevent the onset of ischemia despite prolonged use of a pneumatic tourniquet. The physician accompanying the wound victim to the hospital is able to monitor his or her physiological conditions, to avoid manifestation of complications such as metabolic changes, reperfusion syndrome and cardiac arrest.

In addition, when protuberance <NUM> is secured to the distal advanced position by means of a locking device movably connected to the casing of the gas flow control assembly, the distal end of tube <NUM> will remain indefinitely occluded, allowing the pressurized gas remaining in the gas cartridge to be used for additional hemorrhage suppression operations with respect to other wound victims, following replacement of the inflatable strap.

<FIG> illustrate another embodiment of a pneumatic tourniquet <NUM> which may be compactly stored by means of a plurality of spaced prongs <NUM> extending laterally from gas flow control assembly <NUM>. Prongs <NUM> are insertable in, and connectable to, socket <NUM> provided with housing member <NUM> of non-pivoting constricting device <NUM>. Socket <NUM> is sized to permit connection with prongs <NUM>, yet permit the feeding of inflatable strap <NUM> therebelow along the strap-engageable surface of rocker <NUM>. The prongs <NUM> are pressed together in order to release gas flow control assembly <NUM> from constricting device <NUM>. The operation of gas flow control assembly <NUM> and of constricting device <NUM> is identical to that of gas flow control assembly <NUM> and constricting device <NUM>, respectively, of <FIG>.

<FIG> illustrates another embodiment of a pneumatic tourniquet <NUM> comprising constricting device <NUM> as described in <FIG> and a gas flow control assembly <NUM> lacking a pressure regulating unit to achieve a more compact configuration. Gas flow control assembly <NUM> comprises the same structure of activation handle <NUM> for initiating inflation of strap <NUM>, puncture unit housing <NUM> within which gas cartridge <NUM> is releasably coupleable, and puncture pin <NUM> for puncturing the metallic cover normally sealing the gas cartridge as described above with respect to <FIG> and <FIG>. Connection section <NUM> shown in <FIG> may be used for attachment of strap <NUM> to the gas flow control assembly casing. The flow of pressurized gas discharged from the gas cartridge may be directed to an internal chamber in fluid communication with a safety valve <NUM> shown in <FIG> prior to flowing to the interior of the inflatable strap to prevent occurrences of excessively high pressure.

A plurality of spaced prongs <NUM> (<FIG>) extending laterally from gas flow control assembly <NUM> are insertable in, and connectable to, socket <NUM> provided with housing member <NUM> of constricting device <NUM> to achieve compact storage. The prongs <NUM> are pressed together in order to release gas flow control assembly <NUM> from constricting device <NUM>.

Another embodiment of a pneumatic tourniquet <NUM> is illustrated in <FIG>.

As shown in <FIG>, pneumatic tourniquet <NUM> comprises gas flow control assembly <NUM> provided with user friendly activation handle <NUM>, non-pivoting constricting device <NUM> connectable with gas flow control assembly <NUM>, for example as shown in <FIG> to provide a compact housing without a pressure regulator, and inflatable strap <NUM> which is connected to gas flow control assembly <NUM> and is selectively clamped by constricting device <NUM>. In this embodiment, inflatable strap <NUM> is configured without an internal sealing layer; however, passage of the pressurized gas from a clamping edge associated with constricting device <NUM> to the free end of the strap is prevented by an external sealing element, as will be described hereinafter.

It will be appreciated that inflatable strap <NUM> may also be configured with an internal sealing layer and that pneumatic tourniquet <NUM> may be configured with a pressure regulator.

<FIG> illustrates another embodiment of a gas flow control assembly. Gas flow control assembly <NUM> is shown to be positioned in abutting relation with constricting device <NUM>, when the activation handle is removed. Gas cartridge <NUM>, which is equipped with a valve actuator to initiate the discharge of gas, is shown to be releasably coupled such as by a threaded connection within a piston housing <NUM>, e.g. made of two differently sized sections 468a and 468b. An elongated activation piston <NUM> at a non-activated position protrudes through an opening of piston housing section 468a, such that its head <NUM> is spaced from a laterally extending axle <NUM> (<FIG>), i.e. relative to the longitudinal axis of gas cartridge <NUM>, about which the activation handle is able to rotate. After activation, activation piston <NUM> is returned to the non-activated position by spring <NUM>.

Gas flow control assembly <NUM> may also comprise means for adjusting the gas pressure within the strap interior. A pressure release valve <NUM> for manual release of the internal strap pressure, for example by slow and controlled release of pressure prior to removal from the subject, may be operatively connected to piston housing section 468a. A pressure control mechanism <NUM> for automatic regulation of the internal strap pressure during deployment of the pneumatic tourniquet may be operatively connected to piston housing section 468a by a conduit. Pressure control mechanism <NUM> may have a selector <NUM> by which a user is able to select the pressure to be set.

As shown in <FIG>, inflatable strap <NUM> having two different widths may be configured with a plurality of serially interconnected cells, such as cells <NUM>-<NUM>, adapted to help reduce the volume in the strap interior that is able to be inflated, so that a reduced volume of pressurized gas, relative to a pneumatic strap lacking serially interconnected cells, is needed in order to transmit a sufficient hemorrhage suppressing force to the wounded limb. Each of cells <NUM>-<NUM> is attached to an outer, lengthwise extending border layer <NUM> of strap <NUM>.

A plurality of identical and serially interconnected cells <NUM> may be provided at the narrow-width section <NUM>. Cell <NUM> is provided at the wide-width connection section <NUM>, and transitional cell <NUM> having a change in width is interposed between cell <NUM> and the cell <NUM> that is closest to cell <NUM>. A short lengthwise extending neck portion <NUM> extends between two adjacent cells, to facilitate flow of pressurized gas between one cell to another. Two widthwise protrusions 434a and 434b, e.g. tooth-shaped, extend from opposite sides of a corresponding region of border layer <NUM> to delimit the corresponding neck portion <NUM> and adjoining surfaces of the adjacent cells, generally curved. Inlet port <NUM> through which pressurized gas flows to the strap interior protrudes inwardly through the upper wall of cell <NUM>, and fastening means <NUM> surrounding inlet port <NUM> for connection to the gas flow control assembly casing protrude upwardly from cell <NUM>. Each fastening means <NUM> may be a snapping fastener or other connection means well known to those skilled in the art, whether releasable or inseparable means, and may be spaced from inlet port <NUM> by a different distance. Alternatively, all fastening means may be equidistantly spaced from inlet port <NUM>.

<FIG> illustrate top and side views, respectively, of strap <NUM> when inflated and unconnected with the gas flow control assembly. In addition to wide-width cell <NUM> and transitional cell <NUM>, strap <NUM> is configured with a plurality of narrow-width cells 458a-e, through the adjoining neck portion <NUM> of each cell pressurized gas is able to flow from inlet port <NUM> in order to inflate strap <NUM>. A partition <NUM> adjoining cell 458e and terminal cell <NUM> prevents the flow of pressurized gas to terminal cell <NUM>, ensuring that the uninflated terminal cell <NUM> will be of a minimal thickness so as to be comfortable to the subject when the remaining portions of strap <NUM> are wrapped about a limb of the subject and inflated. Of course, additional portions of inflated strap <NUM> adjoining terminal cell <NUM> that distally protrude from the clamping edge of the constricting device may be uninflated when the pressurized gas is prevented by the clamping edge from flowing to these additional portions.

Each cell is delimited by the external surface <NUM> and limb facing surface <NUM> of strap <NUM> and by the widthwise protrusions <NUM> embedded in each of external surface <NUM> and limb facing surface <NUM>. When strap <NUM> becomes inflated, the widthwise protrusion of external surface <NUM> becomes separated from the corresponding widthwise protrusion of limb facing surface <NUM> to form a pyramidal protrusion <NUM>'. The apex of the pyramidal protrusion <NUM>'protruding from the side of external surface <NUM> meets the apex of a corresponding pyramidal protrusion <NUM>' protruding from the side of limb facing surface <NUM> at the lengthwise extending weld line <NUM>, which is the connecting interface between external surface <NUM> and limb facing surface <NUM>.

<FIG> illustrates strap <NUM> when wide-width cell <NUM> is connected with gas flow control assembly <NUM> and the free end <NUM> of the strap is pre-fed through constricting device <NUM>. A screw <NUM> passing through an aperture <NUM> formed in attachment plate <NUM> of lower casing <NUM> (<FIG>) is shown, and is coupled with corresponding fastening means. A screw <NUM> likewise may pass through an aperture formed in underside surface <NUM> of <FIG> in order to be coupled with corresponding fastening means. The plurality of narrow-width cells <NUM> extend circumferentially to constricting device <NUM>.

<FIG> illustrates a cross-sectional view of connection section <NUM>. Flexible inlet port <NUM> protrudes through external layer <NUM> of the inflatable strap, and its central passageway <NUM> is in fluid communication with the strap interior <NUM> which is located between external layer <NUM> and limb contactable layer <NUM> of the inflatable strap. In order to reduce the stress concentrations to which connection section <NUM> is exposed, a semi-rigid sealing layer <NUM>, e.g. made of polyurethane, thermoplastic polyurethane (TPU), or similar materials, which is formed with an aperture, is attached to both inlet port <NUM> and external strap layer <NUM>, such as by high frequency soldering. The thickness of semi-rigid sealing layer <NUM> may range from <NUM>-<NUM>, e.g. <NUM>. With the exception of the aperture provided to accommodate the inlet port, semi-rigid sealing layer <NUM> is pinhole free. Inlet port <NUM> also protrudes through a rigid plastic plate <NUM> also attached to semi-rigid layer <NUM>, e.g. made of HDPE and polypropylene, from which protrudes a plurality of fastening means, e.g. fastening means 439a-b.

For example, as shown in <FIG>, inlet port <NUM> is configured with a mounting element <NUM> for attachment to semi-rigid layer <NUM>. Rigid plate <NUM> is configured with an aperture <NUM> for receiving inlet port <NUM> and with four bosses <NUM>, each of which connectable with a fastener, e.g. a screw, passing through a corresponding hole formed in an attachment plate of the gas flow control assembly casing. External strap layer <NUM> in turn is formed with four apertures <NUM> to accommodate the bosses <NUM>, respectively, and with a central aperture <NUM> to accommodate inlet port <NUM>. Following assembly, connection section <NUM> appears as shown in <FIG>.

Prior art means for connecting an inflatable strap to a gas flow control assembly generally include a single threaded connection with a valve core. This single connection produces a relatively high stress concentration during deployment of the pneumatic tourniquet while the inflated strap of a relatively high pressure is being wrapped about a wounded limb and applies a relatively high tensile force to the single threaded connection. Many times, pinholes, or small punctures, develop in the strap due to the high stress concentration, resulting in a reduction of the interior strap pressure and wastage of the pressurized gas. The development of high stress concentration at the connection of the inflated strap is exacerbated when the pneumatic tourniquet provides added features found in the present invention such as the pivotable activation handle, constricting device, safety release valve, and self-regulating pressure control mechanism, which, when operated generate vibratory forces that add to the stress concentration.

The relatively high stress concentration is advantageously significantly reduced by use of connection section <NUM>, by which the inflatable strap is connected to gas flow control assembly casing by a plurality of connections, rather than by a single connection. Inlet port <NUM> is coupled, e.g. releasably coupled, with a nipple <NUM> protruding from rigid attachment plate <NUM> (<FIG>) of the gas flow control assembly casing and being a part of piston housing <NUM> (<FIG>), or is otherwise accessible to the attachment plate, and the attachment plate is additionally securely secured to connection section <NUM> by the plurality of fastening means. When the strap is inflated, inlet port <NUM> is pressed against attachment plate <NUM>, and additional pressurized gas is able to flow freely from the gas cartridge to strap interior <NUM>. Semi-rigid sealing layer <NUM> provides added protection against efflux of pressurized gas from connection section <NUM>.

<FIG> illustrates gas flow control assembly <NUM> when activation handle <NUM> is set to a pivoted position. Two laterally spaced, elongated and narrow mounting elements <NUM>, which are substantially perpendicular to substantially planar user-manipulatable surface <NUM>, are rotatably mounted on axle <NUM> to facilitate the pivotal displacement of activation handle <NUM>. The end of one of the mounting elements <NUM> is shown to be in force transmitting relation with activation piston head <NUM>.

<FIG> illustrate the operation of activation piston <NUM>, which functions as a force transmitting element, when cooperating with activation handle <NUM>. Activation piston <NUM> is longitudinally guided within a longitudinal slot formed in piston housing <NUM> (not shown). Activation piston <NUM> carries an angled conduit <NUM>.

In <FIG>, activation handle <NUM> is in a non-pivoted position and activation piston <NUM> is set at the non-activated position while a side edge of a mounting element <NUM> is in abutting relation with activation piston head <NUM>. The distal end of activation piston <NUM> is slightly spaced from the valve stem <NUM> of gas cartridge <NUM>, which is shown to be in a protruding position. At the non-activated position of activation piston <NUM>, the short transversally extending portion of conduit <NUM> is unaligned with a conduit <NUM> fixed to a discharge port <NUM> of piston housing <NUM> and extending through the inlet port of inflatable strap <NUM>, only a portion of which is illustrated, to prevent inflation of the strap due to leakage of the pressurized gas. Leakage of the pressurized gas from gas cartridge <NUM> is also prevented by means of annular seal <NUM> fixed to the base of valve stem <NUM>, also during periods of non-use. Conduit <NUM> is spaced by a very small clearance from activation piston <NUM>.

In <FIG>, activation handle <NUM> is pivoted and transmits the activation force to activation piston <NUM> via head <NUM> while spring <NUM> fixed to a recessed portion of the piston housing becomes compressed. Activation piston <NUM> is consequently longitudinally displaced until the short transversally extending portion of conduit <NUM> becomes aligned with conduit <NUM>. Valve stem <NUM> is consequently contacted by activation piston <NUM> and is caused to become retracted, so that the valve seat will be uncovered and pressurized gas will flow from the interior of gas cartridge <NUM> via the valve seat to conduit <NUM>. Since conduit <NUM> is aligned with conduit <NUM>, the pressurized gas will also flow to the strap interior via the inlet port. A plurality of annular seals <NUM> surrounding conduit <NUM> prevent leakage of gas from the abutment region between conduit <NUM> and conduit <NUM>. In one embodiment, a visually distinctive, schematically illustrated pressure gauge <NUM> in fluid communication with the strap interior is indicative when the strap interior becomes inflated. In another embodiment, the user will terminate the inflation of pressurized gas into the strap interior in response to an audible reaction generated by the pressure control mechanism <NUM> (<FIG>) when gas is released therefrom.

Upon release of the activation force, the spring force of spring <NUM> surrounding activation piston <NUM> is released to urge activation handle <NUM> to the non-pivoted position and conduit <NUM> to become unaligned with conduit <NUM>, as shown in <FIG>. Also, the spring surrounding valve stem <NUM> ceases to be compressed, and the valve stem returns the protruding position.

Alternatively, activation piston <NUM> may be longitudinally driven by means of a button <NUM>, or any other actuator, protruding from lower casing <NUM> of gas flow control assembly <NUM>, as shown in <FIG>. Upon transmission of the activation force, a movable rod <NUM> connected to, or in force transmitting relation with, button <NUM> is longitudinally driven to proximally displace activation piston head <NUM>. The operation of the activation piston is as described above.

It will be appreciated that activation piston <NUM> may be used to drive puncture pin <NUM> shown in <FIG>.

The pressurized gas discharged from gas cartridge <NUM> following transmission of the activation force may be in fluid communication with pressure release valve <NUM> and pressure control mechanism <NUM> by means of corresponding conduits also fixed to piston housing <NUM>. Conduit <NUM> carried by activation piston <NUM> may be configured with additional angled portions, each of which is alignable with a corresponding conduit similar to the manner shown in <FIG> following transmission of the activation force. In order to provide the desired pressure control function, each of the corresponding conduits may be equipped with a valve or other pressure biasing mechanism, and optionally with a sealing element.

Reference is now made to <FIG>, which illustrates a cross sectional view of a portion of constricting device 448A. Housing member <NUM> and rocker <NUM> are configured similarly to, and have a similar function as, their counterparts of <FIG>, with the exception of the addition of sealing element <NUM>. The distance from axle <NUM> by which rocker <NUM> is pivotally displaceable to proximal leg <NUM> is significantly shorter than the distance to distal leg <NUM>. Distal leg <NUM> may be significantly longer than proximal leg <NUM>. Also the sidewalls <NUM> of housing member <NUM> are formed with a thin interspace, within which longitudinally extending external sealing element <NUM> is secured. External sealing element <NUM> is also shown in <FIG> and <FIG>. When rocker <NUM> is rotated in response to contact made with the wounded limb and to a tensile force applied onto inflatable strap <NUM> as shown in <FIG>, a clamping force is applied onto the strap. External sealing element <NUM> positioned at the clamping edge, which is preferably semi-rigid, for example having a Shore index of <NUM>, complements the clamping force to prevent the pressurized gas from flowing to the free end of strap <NUM>. Thus the free end of the strap is uninflated, so as to be more comfortable to the subject and to be less prone to puncture.

<FIG> illustrates a constricting device 448B configured with an external sealing element <NUM> attached to proximal leg <NUM> of the rocker.

<FIG> illustrates a constricting device 448C configured with both external sealing element <NUM> and external sealing element <NUM>.

The tourniquet of <FIG>, for example, is well suited for combat implementations and for a small-sized tourniquet that can be compactly stored in a soldier's backpack or other piece of storage equipment.

The following are some of the advantageous features of such a small-sized tourniquet:.

Claim 1:
A pneumatic tourniquet (<NUM>), comprising
an inflatable strap (<NUM>) adapted to receive pressurized gas and to be wrapped around a wounded limb to provide a desired hemorrhage suppressing force, wherein the strap includes an inner layer (<NUM>), an outer layer (<NUM>), and an intermediate sealant layer (<NUM>) that are interconnected;
a casing (<NUM>, <NUM>) having a puncture unit housing (<NUM>) with which a gas cartridge (<NUM>) filled with the pressurized gas is coupled, a puncture pin (<NUM>) that terminates with a pointed end (<NUM>), and an outlet port (<NUM>);
means (<NUM>) for drivingly contacting the puncture pin to an inwardly displaced position at which the pointed end of the puncture pin punctures a puncturable cover (<NUM>) normally sealing the gas cartridge, causing the pressurized gas to be discharged from the gas cartridge and flow via the outlet port to an interior of the inflatable strap;
a constricting device (<NUM>) adapted to receive a free end (<NUM>') of the strap (<NUM>) in such a way that the free end is unrestrainably displaceable within the constricting device until being clamped thereby when the strap is sufficiently tensioned to transmit the desired hemorrhage suppressing force;
wherein the constricting device comprises a housing member (<NUM>) and a rocker (<NUM>) rotatably mounted onto, and within, the housing member by a longitudinally extending axle (<NUM>), the rocker being configured to be angularly displaced about the axle until a planar surface (<NUM>) of the rocker is set in clamping relation with a clamping edge (<NUM>) of the housing member while the strap is interposed between the planar surface and the clamping edge, in response to a force applied by the wounded limb onto the rocker when the strap is sufficiently tensioned,
wherein a clamping force applied by the rocker surface and the clamping edge onto the intermediate sealant layer prevents flow of the pressurized gas from a pressure applying section (<NUM>) of the strap which is wrapped around the wounded limb to the free end of the strap, causing the free end to be considerably thinner than the pressure applying section.