A radial artery compression device for patent haemostasis

Abstract

A haemostatic device has a support body (104), a strap (103) with fasteners (105, 106) attached to the body, and a cushion (125) having a wound sealing and compression zone (126) which is at least partly transparent. A lens (120) is aligned with the wound sealing and compression zone (126) to provide visibility of a wound site through only one wall, that of the cushion. The cushion (125) is dome-shaped, and the lens (120) is convex. The cushion skin-contacting material (126) has a surface roughness to allow excellent skin engagement to avoid need for inflation pressure, and upon compression it engages with the skin to provide better transparency. A volume within the cushion can be sealed to that it is at ambient pressure. The device body and fasteners form a generally concave shape to encompass part of the wrist of a patient, and achieve a direction of engagement near the Radial Artery which is normal to the skin at that location.

Description

[0001] “A Radial Artery Compression Device for Patent Haemostasis”

[0002] Introduction

[0003] The present invention relates to a device to apply compression in order to achieve haemostasis while allowing the user to maintain patency of the radial artery (“patent haemostasis”). It is alternatively referred to as a “haemostatic device”.

[0004] US2022 / 0330949 (Biolife) describes a compression balloon with a rigid foot for haemostasis. JP2013-78529 describes a device in which pressure is applied by a coil spring mechanism. CN115721371 and CN202036272 describe devices with threaded driving piece to be rotated to apply pressure. CN212015692 describes a device with a pressure chamber and a gauze, and a convex lens.

[0005] Radial artery access for angioplasty procedures, known as trans radial access (TRA), is increasingly favoured in clinical practice due to its lower complication rates and enhanced patient comfort compared to femoral access. Effective haemostasis post-procedure prevents complications such as bleeding, hematoma, and radial artery occlusion. Under FDA, devices to assist in these situations are classified as vascular clamps.

[0006] Known devices function by applying targeted pressure to the radial artery puncture site, ensuring cessation of bleeding while maintaining distal circulation. Typically, the device is carefully positioned directly over the radial artery puncture site, ensuring optimal placement for effective pressure application. Transparent components of the device allow for visual monitoring of the site.

[0007] The air bladder or mechanical mechanism of the device is gradually inflated or tightened to apply sufficient pressure to achieve haemostasis. This step requires careful adjustment to balance haemostasis and patient comfort, ensuring the distal radial pulse remains palpable. Continuous monitoring is essential to assess the effectiveness of the applied pressure. Adjustments are made as necessary to maintain haemostasis without compromising blood flow to the hand. Monitoring involves checking for cessation of bleeding and ensuring adequate perfusion to the distal extremity. Following the initial period of compression, the pressure is gradually released over 1-2 hours. This controlled release minimizes the risk of re-bleeding and allows the vessel to adapt to the decreasing pressure. Careful observation during this phase ensures any signs of bleeding are promptly addressed. After achieving complete haemostasis, the device is removed, and a sterile dressing is applied to the puncture site. Patients are advised to avoid strenuous activities and heavy lifting with the affected arm for 24-48 hours to prevent re-bleeding.

[0008] The present invention is directed towards providing an improved device. It is especially aimed at achieving improved ease of use, more consistent and uniform pressure at the wound site with little adjustment or caregiver time required, and / or reduced risk of patient pain.

[0009] Summary of the Invention

[0010] We describe a haemostatic device comprising: a support body extending in a longitudinal direction from a proximal end to a distal end, a strap attached to, or for attachment to, the body to extend in the longitudinal direction, a cushion mounted to the support body, and having an inner wall with a wound sealing and compression contact surface and which is at least partly transparent, and a lens aligned with the wound sealing and compression surface to provide visibility of a wound site via the cushion wall, wherein the cushion is mounted to the support body on an inner side and the lens is mounted on an outer side of the cushion, and the lens and the cushion at least partly enclosing a volume.

[0011] In some preferred examples, the cushion is capable of withstanding a pressure in the range of 40 to 200 mmHg for a displacement up to 5 mm at the centre of the contact surface, without need for inflation.

[0012] In some preferred examples, the cushion is capable of withstanding a pressure in the range of 80 to 160 mmHg for a displacement up to 3 mm at the centre of the contact surface, without need for inflation.

[0013] In some preferred examples, the lens is a convex lens.

[0014] In some preferred examples, the device presents only the lens and the cushion wall for wound visibility in a line of sight through the device.

[0015] In some preferred examples, the cushion is of a material which includes silicone.

[0016] In some preferred examples, the cushion is of a material which has a Shore A hardness in the range of 5 to 80, preferably 20 to 40.

[0017] In some preferred examples, the strap is of a moisture / gas permeable material with a Shore D value in the range of 30 to 45.

[0018] In some preferred examples, the cushion contact surface has a surface roughness in the range of 0.4 um to 3.0 pm Ra, preferably in the range of 0.8 to 2.3 pm Ra.

[0019] In some preferred examples, the strap is of a porous material, having an MVTR value in the range of 800 to 4900 g / m2 / 24h, to provide breathability.

[0020] In some preferred examples, the cushion is of a gas permeable material, having an MVTR value in the range of 100 to 300 g / m2 / 24h, to provide gas and vapour exchange for wound healing.

[0021] In some preferred examples, the cushion and the lens enclose a volume in the range of 5 cm3to 15 cm3.

[0022] In some preferred examples, the cushion and the lens enclose a volume in the range of 5 cm3to 9 cm3.

[0023] In some preferred examples, the cushion is elongate, with a major axis in the longitudinal direction, and having a proximal wall, side walls, and a distal wall.

[0024] In some preferred examples, the distal wall has a greater stiffness and less deformability than the proximal wall.

[0025] In some preferred examples, the cushion has a visible feature in a central region of the inner wall. Preferably, the feature is cross-shaped.

[0026] In some preferred examples, the cushion contact surface has an area in the range of 400 mm2to 750 mm2, and the contact surface is that part of the cushion external surface which extends at an angle greater than 15° from the cushion walls.

[0027] In some preferred examples, the contact surface comprises a raised region having a convex shape which is raised from a surrounding region. In some preferred examples, the raised region extends to a distance in the range of 0.5 mm to 2.0 mm from the surrounding region.

[0028] In some preferred examples, the body forms a concave shape in the longitudinal direction.

[0029] In some preferred examples, the support body internal surface median plane (Pl) at its proximal end and its internal surface median plane (P3) at its distal end subtend an angle on the distal side in the range of 10° to 45°.

[0030] In some preferred examples, the body has a strap fastener extending from the distal end of the body, and said fastener internal surface has a median plane (P4) which extends at an angle in the range of 15° to 45° on the distal side relative to the distal end of the body.

[0031] In some preferred examples, the cushion proximal wall has an external surface extending at an angle in the range of 110° to 140° on the proximal and inner side to the plane (Pl) of the body proximal end internal surface.

[0032] In some preferred examples, the cushion proximal wall extends from the body to a lesser extent than the cushion distal wall.

[0033] In some preferred examples, the device further comprises a conduit in fluid communication with a volume formed by the cushion and the lens, said conduit venting said volume.

[0034] In some preferred examples, the device further comprises a vent valve which is normally open, and which allows a user to close the valve so that the volume is closed for use.

[0035] In some preferred examples, the valve comprises a vent plug for removal from a socket to close the vent.

[0036] In some preferred examples, the vent plug has a tip with a tubular configuration whereby it performs opening of the valve when inserted in a manner similar to insertion of a syringe tip.

[0037] In some preferred examples, the cushion has greater stiffness at the distal end than on the proximal end. In some preferred examples, the cushion has only one layer of material, presenting only one layer between the lens and the skin in use.

[0038] In some preferred examples, the strap comprises serrated edges to allow the strap to be easily cut or torn to a required length.

[0039] In some preferred examples, the cushion comprises a coating of a material which is non- pharmacological and non-biological.

[0040] We also describe a haemostatic device comprising: a support body, a strap with fasteners attached to the body, a cushion mounted to the support body, and having a wall with a wound sealing and compression zone which is at least partly transparent, and a lens aligned with the wound sealing and compression zone to provide visibility of a wound site via the cushion wall.

[0041] In some preferred examples, the cushion is dome-shaped, mounted to the support body on a distal side and the lens, and the lens is mounted on a outer side of the support body.

[0042] In some preferred examples, the cushion has sufficient resilience to avoid need for inflation, the cushion wall shape and material being capable of withstanding a pressure in the range of 40 to 200 mmHg without need for inflation.

[0043] In some preferred examples, the lens is a convex lens. In some preferred examples, the device presents only the lens and the cushion wall for wound visibility in the line of sight through the device. In some preferred examples, the cushion has a rim defining the wound contact and compression zone.

[0044] In some preferred examples, the cushion has a rim defining an annular outer zone surrounding the wound contact and compression zone. In some preferred examples, the device further comprises a pressure indicator to provide a user indication of pressure in the cushion as an indicator of pressure applied to a wound. In some preferred examples, the lens forms a volume together with the cushion and the pressure indicator is arranged to sense pressure in said reservoir.

[0045] In some preferred examples, the conduit comprises a probe stem extending from a wall of the lens, or a strain gauge sensor on or in the cushion wall. In some preferred examples, the cushion is of a material which includes silicone.

[0046] In some preferred examples, the cushion is of a material which has a Shore A hardness in the range of 5 to 80, preferably 00 to 40.

[0047] In some preferred examples, the cushion wall skin contacting surface has a roughness in the range of 0.4 um to 3.0 pm Ra. In some preferred examples, said roughness is in the range of 0.8 to 2.3 pm Ra.

[0048] In some preferred examples, the strap is of a porous material, having MVTR (Water Vapour Transmission Rate) values range from 800 to 4900 g / m2 / 24h, to provide breathability.

[0049] In some preferred examples, the cushion is elongate, with a major axis in the direction of the strap. In some preferred examples, the cushion has a varying wall thickness in a direction along the major axis, with greater stiffness and less deformability on one end than on the opposed end in the major axis direction.

[0050] In some examples, the cushion wall has at least one rib facing into a volume of the cushion. In some such examples, the cushion wall has at least one the rib facing into a volume of the cushion and extending along the major axis.

[0051] In some preferred examples, the cushion wall is configured to have less stiffness between opposed ends along the major axis, to provide greater spreading of a central cushion wall region with application of pressure in use against the skin.

[0052] In some preferred examples, the cushion skin-contacting wall has a visible feature in a central region. In some preferred examples, the feature is an embossing, and the feature is preferably cross-shaped. Detailed Description of the Invention

[0053] The invention will be more clearly understood from the following description of some embodiments thereof, given by way of example only with reference to the accompanying drawings in which:

[0054] Figs. 1 and 2 are top perspective views from different angles of a radial artery compression device of the invention,

[0055] Fig. 3 is an underneath perspective view,

[0056] Fig. 4 is an underneath plan view of the device without its strap, showing particular detail of the contact surface of the cushion,

[0057] Fig. 5(a) is a diagrammatic sectional view through the device and a user’s wrist when the device is in use, with arrows showing the primary compression direction and reaction forces, and Fig. 5(b) is a diagram showing the directions of planes of components of the device,

[0058] Fig. 6 is a cross sectional view across the device,

[0059] Fig. 7 is a cut-away perspective view of a cushion of the device, also across the cushion,

[0060] Fig. 8 is a side view of the cushion extending from proximal on the right to distal on the left in the direction of the strap, and Fig. 9 is a side sectional view in this direction of the cushion,

[0061] Fig. 10 is a perspective view of another radial artery compression device of the invention,

[0062] Fig. 11 is a perspective view of the device of Fig. 10 from a different direction,

[0063] Fig. 12 is a diagrammatic side cut-away view of the device, showing some internal features of the cushion, Figs. 13 to 16 inclusive show top perspective, underneath perspective, top plan, and underneath plan views respectively of the cushion,

[0064] Figs. 17 and 18 are perspective views showing the device in use,

[0065] Figs. 19 and 20 are top and underneath perspective views of another device of the invention,

[0066] Fig. 21 is plan view of the device of Figs. 19 and 20, and Fig. 22 is a side view,

[0067] Fig. 23 is a top perspective view of the cushion of the device of Figs. 19 to 22, Fig. 24 is a side view, and Fig. 25 is a set of three cut-away views illustrating particularly the wall thicknesses of the cushion,

[0068] Figs. 26(a) to (e) inclusive are diagrams showing use of the device of Figs. 19 to 25,

[0069] Fig. 27 is a perspective view showing addition of skin-contacting layers for a device of any example, and

[0070] Figs. 28(a) is a perspective view and Figs. 28 (b), and (c) are cut-away views respectively showing an alternative cushion, in which Fig. 28(b) is cut along a major, longitudinal, axis which extends across the wrist in use (aligned with the strap) and Fig. 28(c) is cut away along the minor axis (in the direction of the user’s arm in use).

[0071] Device of Figs. 1 to 9

[0072] Referring to Figs. 1 to 9 a radial artery compression (“haemostatic”) device 100 comprises a cushion assembly with a cushion 125 mounted to a generally ring-shaped rigid body 104. The body 4 also supports a convex lens 120 on the upper side for visibility of a wound site through the lens 120 and the cushion 125.

[0073] A strap 103 extends from a strap support 105 at the proximal end of the body 104 and is configured for engagement through a strap loop back support or tab 106 on the opposite, distal, end of the body 104.

[0074] In this specification the longitudinal direction is defined as the direction of the strap 103, which in use is across the user’s wrist. The tab 105 is defined as being proximal and the loop back support 106 as being distal.

[0075] The lens 120 has an opening near its edge which receives a flexible tube 111 continuing from a rigid tube 112, at the other end of which is a valve 113 to seal the cushion from atmosphere. The valve 113 is normally closed, and in this example is of the type referred to as a needleless injection site valve. It is normally closed, and opens when a tubular element of the correct size, such as the tip of a syringe is inserted. The device 100 has a vent plug 114 which is so configured and so opens the valve 113 when it is inserted.

[0076] The cushion 125 is open to atmosphere via the tubes 111 and 112 and the vent plug 114 during transport until use, and is sealed by removal of the vent plug 114 to activate it. This guarantees a minimum pressure at the wound site of 150 mmHg. Hence, even if the device is subjected to wide ambient pressure variations during transport, such as in a cargo plane or at a high altitude, it is not adversely affected. Prior to use the vent plug 114 is removed to seal the volume enclosed by the cushion-lens combination, so that the stiffness of the device at the wound site is primarily derived from the cushion materials and not by pneumatic inflation. Hence the stiffness is predictable at manufacture.

[0077] However, as shown by the syringe 115 the volume enclosed by the cushion / lens combination may in exceptional circumstances be inflated using a standard Luer syringe, typically a 5 ml syringe.

[0078] The strap 103 is adhered to the outer surface of the body 104, as best shown in Fig. 4(a). This provides excellent integrity of the anchoring of the strap in the device. In some examples, the strap at this end surrounds part of the lens. Also, this also helps to achieve a low profile for the device.

[0079] The cushion assembly comprises the lens 120 on the outer side (furthest from the patient’s skin in use) and the cushion 125 on the inner side, for engaging the patient’s skin. The lens 120 has a shallow dome shape.

[0080] The cushion 125 is configured to engage the patient’s skin at a wound site in a manner which has minimal pressure, which is dictated by the resilience of the cushion 125 and geometry and tightness of the strap 103. The cushion is sealed in use as the vent plug 114 is removed before use to activate the device. The cushion is of silicone and the strap is of TPC-ET which both are gas and moisture permeable, the strap having an MVTR (moisture vapour transmission rate) value in the range for the strap 800 to 4900 g / m2 / 24h, and the cushion material range is 100 to 300 g / m2 / 24h to provide good breathability and coagulation, and also good placement and closure.

[0081] As shown in Fig. 4 the cushion 125 has a contact surface 126 which is elongate in the longitudinal direction. In this example it is slightly wider in the transverse direction at the proximal end, tapering distally.

[0082] The cushion 125 is shown most clearly in Figs. 6 to 9. It is dome shaped and the wound site seal and compression contact zone or contact surface 126 is bounded by the walls of the cushion, namely a proximal wall 130, side walls 128, and a distal wall 131. The cushion 125 also has a flange 129 for attachment to the support body 104 around the lens 120.

[0083] The contact zone 126 is the surface of the cushion within the walls 130, 128, and 131, which is defined as that part of the surface which extends at an angle greater than 15° from the walls. The directions of the side walls 126 are indicated as P6 and P7 in Fig. 7, and the contact surface 126 is defined as that surface which extends at an angle greater than 15° from P6 and P7, and similarly with respect to the end walls 130 and 131 (best shown in Fig. 9). The cushion 125 has a central generally convex region 135 surrounded by a region 136 which adjoins the cushion walls, the regions 135 and 136 providing the contact surface 126. The cushion 125 has an internal raised region 127 which is coaxial with the external convex portion 135. It is in the form of a cross-hairs. This crosshairs feature 127 is visible through the lens 120. The device has the major advantage of not having any interruption in the line-of-sight through the lens and through the lower wall of the cushion 125

[0084] Advantageously, the contact surface 126 has an area of about 600 mm2and more generally it is preferred that the contact surface has an area in the range of 400 mm2to 750 mm2.

[0085] The function of the cushion 125 is to provide compression and sealing to the wound site at the radial artery (RA in Fig. 5(a), the Ulnar Artery being UA), in a manner which conforms to the anatomical location of application on the wrist. The lens 120 provides visibility to the user to accurately apply the device on the patient with respect to sheath removal from the radial artery. The wound seal and compression contact zone or surface 126 acts as a clearly visible target, particularly with the help of the raised internal cross-hairs region 127 and the fact that there is no interruption in visibility, the line of sight to the skin being only through the lens 120 and the cushion wall providing the contact surface 126.

[0086] The contact surface’s central convex, gradually raised, region 135, and the surrounding annular region 136 together provide a dual redundancy seal between the cushion 125 and the skin to minimise unnecessary leaks of radial artery blood from being exposed beyond the immediate wound site. The raised region 135 extends to a height when relaxed relative to the surrounding region 136 by 1.5 mm, and more generally preferably in the range of 0.5 mm to 2.0 mm, and it forms the distal end or tip of a convex dome surface provided by the cushion.

[0087] The cushion 125 together with the lens 120 form a reservoir having a capacity in the range of 5 cm3to 15 cm3. The cushion 125 minimizes over-compression of the wound site due to the strength provided by the side walls 130, 128, and 131. And the large surface area and shape of the surface of the cushion 125 which is contact with the wound side.

[0088] The cushion 125 and the lens rim 104 have a domed shape which allows good visibility and (may provide magnification) of the wound site via the convex lens 120. It supports compression and sealing by providing mechanical structural support, where translation of compression from the strap is transferred to the compression and sealing of the wound at suitable closure pressure, as best illustrated in Fig. 5(a) in which arrows illustrate the light force applied and the reaction force. This pressure is applied over the contact surface 126, which as shown in Fig. 4 is quite large (600 mm2in this example) and is elongate with a tapered reduction in the transverse dimension as it extends distally.

[0089] The strap 103 is of a moisture / gas permeable material such as Thermoplastic Co-Polyester (TPC). It is of a highly elastic material with a Shore D value preferably in the range of 30 to 45 and in this example 34 D. The strap width is sufficient so that the load across the ulnar artery is at minimum. In combination with the lens structure this provides additional support and reduces load on the ulnar artery. Hook and loop fasteners are used to close and secure the strap 103. The closure system has sufficient shear closure strength to ensure minimal compression and sealing of the wound site, with peel release of the strap sufficiently strong that the device will not release due to normal arm movements of the patient; it will require clinical personnel to secure and remove the device. The strap 103 is easy to apply and has a low-profile format to minimise the risk of the patient tampering with the device in conjunction with improved comfort but can be removed without disturbing the healing wound site by the accompanying clinical personnel. Its preferred thickness is in the range of 0.5 mm to 0.7 mm. Also, because it is laminated to the body 104 it has a low profile.

[0090] Referring particularly to Figs. 5 to 9 the support body 104 and the cushion 125 define various planes as illustrated and the relative angles of these planes are very advantageous for functioning of the device 100. These planes are as follows:

[0091] Pl, the median plane of the internal (skin-facing) proximal end of the body 104. As shown in Fig. 5(a) is in over the centre of the wrist proximally of the Radial Artery RA.

[0092] P2, the external surface of the proximal cushion wall 130. It is preferred that this forms an obtuse angle to the plane Pl on the proximal and inner side, so that it is tapered distally. In this example the above angle is 125° and in general it is preferred that it is in the range of 110° to 140°. Also, advantageously, the cushion proximal wall 130 extends from the body 104 proximal end to a lesser extent than the cushion distal wall 131 does from the body 104 at the distal end.

[0093] P3, the median plane of the internal surface of the distal end of the support 104. This is at an angle to Pl on the distal side of 20°, and preferably is in the range of 10° to 45°. It is this plane which primarily provides that the device in the longitudinal direction has an overall concave configuration and follows the contours of the patient’s wrist in use, and allows the cushion to be approximately normal to the Radial Artery RA in use and avoid rocking or slippage.

[0094] P4, the median plane of the internal surface of the distal tab 106. This is at an angle of 30° to P3 on the distal side, and in general it is preferred that it is in the range of 15° to 45°. Again, this contributes to the concave configuration and wrap-around functionality of the device.

[0095] P5, the plane of the distal cushion wall 131 outer surface. This is generally preferred to be approximately normal to the plane P3, for maximum compression resistance. It is preferred that its angle to the plane P3 is in the range of 70° to 110°. Also, it is preferred that the distal wall 131 extends from the body 104 to a greater extent than the proximal wall 130 does.

[0096] As shown in Fig. 5(a) by the arrows at the centre of the cushion contact surface 126 the above angles provide that there is approximately normal contact between the contact surface 126 and the patient’s skin at the location of the Radial Artery RA. This greatly helps to achieve a uniform and consistent contact pressure without pinching. The effectiveness of the contact is helped by the convex protrusion 135 at the centre of the contact surface 126 and that there is only atmospheric pressure (sealed) in the cushion (bounded on its upper side by the lens 120). It is also helped by the fact that the proximal end wall 130 is at an obtuse angle in the range of 110° to 140° to the plane Pl, and that the distal end wall 131 is at or close to normal to the distal rim plane P3. The arrangement of the distal wall provides maximum wall height from the distal end of the support 104 and compression resistance.

[0097] Also, the angle between P3 and Pl and that between P4 and P3 provide that the tab 106 continues in a direction that follows the wrist anatomy, thereby helping to achieve a uniform application of pressure for wound sealing and comfort. This is also assisted by the cushion having a depth which increases in the distal direction, being tapered from the proximal end wall 130 to the distal end wall 131.

[0098] As noted above, prior to use the vent plug 114 is removed so that the volume is sealed. This avoids risk of over-inflation by a user, the level of pressure for a given strap tightness being predictable, as it arises from the material and configuration of the cushion as described above. In this example the enclosed volume at atmospheric pressure is 6.7 cm3, and is more generally preferably in the range of 5 to 15 cm3, and more preferably 5 to 9 cm3. The cushion, without need for inflation, has a resistance of deformation, whereby a force of about 40 mmHg to 200 mmHg normal to the centre of the contact surface (in use, at the wound site), causes a deformation in the range of 1 mm to 5 mm. It is more preferred that the cushion presents a resistance at the centre of the contact surface in the range of 80 to 160 mmHg, for a 1-3 mm displacement.

[0099] Also, the device 100 has the advantageous feature that the contact surface 126 has a satin finish with a surface roughness in the range of approximately 0.4 pm to 3.0 pm, preferably 0.8 to 2.3 pm. This provides that, as the cushion 125 is pressed lightly against the skin at the wound site, the surface roughness of the material causes the visibility to change from translucent to transparent. This is helped by the fact that the contact surface 126 has the convex projection 135 relative to the surrounding contact surface portion 136. These aspects are also helped by the material of the cushion walls having a hardness in the range of 5 to 80 Shore A, more preferably 20 to 4 Shore A.

[0100] Embodiment of Figs. 10-18

[0101] Referring to Figs. 10 to 19 another radial artery compression (“haemostatic”) device 200 comprises a cushion assembly 202 on a ring-shaped body 204, and a strap 203. The strap 203 extends from a proximal tab 205 of the body 204 and is configured for engagement through a strap loop back support 206 on the distal side of the body 204. Again, the strap is of a porous silicone material, having an MVTR (moisture vapour transmission rate) value in the range from 800 to 4900 g / m2 / 24h, to provide breathability and improved coagulation, and also better placement and closure.

[0102] In this example, the cushion is circular in plan and has a uniform depth, not being wedge shaped in the longitudinal direction. Hence, the device 200 is more suited to use with children or smaller adults. Again, the cushion assembly 202 is configured to engage the patient’s skin at a wound site. This engagement has minimal pressure.

[0103] The cushion assembly 202 comprises a lens 220 on the outer side (furthest from the patient’s skin in use) and a cushion 225 on the inside for engaging the patient’s skin. The lens 220 has a shallow dome shape and has an opening 214 through which a stem 211 of a probe 210 is inserted. The probe 210 has a handle 213 and an indicator 212 which slides outwardly under pressure via the stem 211 and is retracted without pressure. As shown in Fig. 12 the lens 220 has a wall with ribs 221 to provide a desired level of stiffness and a transparent lens element 222 to provide visibility distally to the wound site. The device therefore allows improved visualisation of the wound site, enabling detection of end point haemostasis. Alternatively, an internal pressure sensor may be provided, such as a strain gauge embedded sensor in the surface of the cushion.

[0104] The cushion 225 is shown most clearly in Figs. 13 to 16. It is also dome shaped and has a wound site seal and compression zone 226(a) in the form of a disc-shaped wall bounded by a ridge-shaped rim 226 on the inside of the cushion. There is a concentric outer ridge or rim 227 forming an outer sealing zone to apply (minimal) pressure to the wound site and prevent blood spill. The cushion 225 also has a side wall 229 which is strengthened to the desired extent by radial ribs 230, to achieve a desired very low level of compressibility and minimum compression recovery upon release of strap tightening. The cushion 225 also has a flange 228 for attachment to the body 204 in a manner aligned with the lens 220.

[0105] The function of the cushion 225 is to provide very low compression and sealing to the wound site, in a manner which conforms to the anatomical location of application on the wrist. The lens 220 provides visibility to the user to accurately apply the device on the patient with respect to sheath removal from the radial artery. As for the device of Figs. 1 to 9, there is no interruption in line of sight between the lends 220 and the skin-contacting cushion wall. The wound seal and compression zone 226(a) acts as a clearly visible circular target ring formed by the proximal side of the rim 226 (see particularly Figs. 13 and 15). The ribs 230 limit compression of the cushion 225 and provide that the volume of inflation air needed for compression is very small. They help target the longitudinal compression of the radial artery and ensure an evenly distributed load across the wound site.

[0106] The inner and outer rims 226 and 227 provide a dual redundancy seal between the compressed cushion 225 and skin to minimise unnecessary leaks of radial artery blood from being exposed beyond the immediate wound site. The rim 226 is a circular extruded surface with a distal dimension (rim / ridge height) preferably in the range of 0.5 mm to 1 mm, and it forms the distal end or tip of a convex dome surface provided by the cushion.

[0107] In general, it is preferred that the height of the inner rim (or “ridge”) 226 is in the range of 0.5 mm to 2.0 mm, and the height of the outer rim (or “ridge”) 227 is in the range of 0.5 mm to 3.0 mm. It is preferred that the diameters of the wound contact zones encircled by the rims is in the range of 5 mm to 10 mm for the inner zone (within the rim 226) and 8 mm to 20 mm for the outer zone (within the rim 227).

[0108] The cushion 225 together with the lens 220 form a reservoir having a capacity in the range of 5 cm3to 15 cm3. The cushion 225 minimizes over-compression of the wound site due to the strength provided by the ribs 230. The strap indicator 210 will inflate with pushing of the indicator 212 upwardly when the strap is secured correctly at the correct tension.

[0109] The proximal portions 205, 220 of the device have a domed shape which allows good visibility and magnification of the wound site via the convex lens portion 222. It supports compression and sealing by providing mechanical structural support, where translation of compression from the strap is transferred to the compression and sealing of the wound at suitable closure pressure. Also, it enables strap ease of assembly. The lid 220 preferably has a high stiffness and toughness, and the lens 222 has good visible light transmission (high transparency) for wound visibility.

[0110] The strap 203 is of a moisture / gas permeable material such as Thermoplastic Co-Polyester (TPC). It is of a highly elastic material with a Shore D value preferably in the range of 30 to 45 and in this example its 32 D (VT 3014). The strap width is sufficient so that the load across the ulnar artery is at minimum. In combination with the lid-lens structure this provides additional support and reduces load on the ulnar artery. Hook and loop fasteners 203(a) are used to close and secure the strap 203. The closure system has sufficient shear closure strength to ensure minimal compression and sealing of the wound site, with peel release of the strap sufficiently strong that the device will not release due to normal arm movements of the patient; it will require clinical personnel to secure and remove the device. The strap 203 is easy to apply and has a low-profile format to minimise the risk of the patient tampering with the device in conjunction with improved comfort but can be removed without disturbing the healing wound site by the accompanying clinical personnel.

[0111] Device of Figs. 19 to 27

[0112] Referring to Figs. 19 to 25, another radial artery compression device, 300, comprises a cushion assembly 302, a rigid body or frame 305, a lens 320, a strap 303, a probe 303 with a stem 311, and a cushion 325. A syringe S is shown for inflating the cushion however, as for the devices 100 and 200, this is not normally needed due to the configuration of the cushion. The strap 303 has a thinner end with side indentations 303(a) for easy trimming without necessarily needing a scissors to optimise the device for a particular patient.

[0113] Features and components of the device 100 can be used in the devices 200 and 300 and other devices of the invention where applicable as would be readily understood by a person of ordinary skill in the art. For example, the planes P1-P7 of Figs. 1 to 9 are present in the device 300. For example, the plane Pl is that of the proximal end of the body 305, and the plane P4 of the distal strap holder of the body.

[0114] The view in Fig. 21 shows a cross-shaped embossing 326 in the skin-contacting cushion wall, visible through the lens 320.

[0115] Referring particularly to Figs. 23 to 25 the cushion 325 has a rim 327 for engaging the frame 305 and a non-symmetrical resilient body. The cushion 325 is elongate in a longitudinal direction aligned with the strap 303, referred to as the major axis (350 in Fig. 19), across the patient’s wrist in use. It has a distal end with a relatively thick wall 328, and a proximal end with a thinner wall 329. In-between there is a wall region 326 to allow visibility of the wound site via the proximal lens 320, due to the region 326 being in intimate contact with the skin and being transparent. It is advantageous that the cushion 325 is elongate, with the major axis (longitudinal direction) 350 in the direction of the strap, and that the cushion wall has a varying thickness in a direction along the major axis.

[0116] In more detail, the bottom two views of Fig. 25 show a section along the major axis 350. Starting at the distal end there is a thick wall 328 and this is located on the distal end which anchors the strap 303 (left side of Fig. 19). The wall has a central region 326 for the lens and then further along the major axis 350 it is thinner at 329. The higher thickness wall 328 provides additional stiffness, thereby allowing avoidance of need for inflation and also preventing movement of the device and providing stability on the wrist in use about an axis along the user’s arm. The distal cushion wall 328 tends to remain filling a space on the thumb side of the wrist in use.

[0117] The devices 100 and 300 with cushions having an elongate shape in the longitudinal direction are particularly advantageous for application on the wrist of older children and adults, whereas the device 200 with a symmetrical arrangement is advantageous for younger children and where the wrist is closer to circular in cross section, or for other applications such as at the access point in the hand between the thumb and index finger. The symmetrical arrangement of the device 200 is likely to be more suited for Distal Radial Access (DRA) in the anatomic snuffbox or on the dorsum of the hand.

[0118] As shown by the top view of Fig. 25 the cushion wall 326 is the same at the two extremities along the minor axis, across the device. Importantly, the wall 326 has a resilience to allow the skin contacting surface 330 to expand along the minor axis in use when the strap 303 is tightened if required. This provides good, enhanced sealing load distribution along the RA. The feature visible in the wall 326 isa crosshairs to allow improved alignment with the wound site. Alternatively, the wall at this location may be uniform with only a printed crosshair. Advantageously, there is a marker on the distal side contacting the skin. This may alternatively be a coloured mark such as a dot.

[0119] In this case there are no internal ribs, nor external rims. The external surface of the cushion does not have any projections. It has been found that a variable wall thickness across the wrist in use provides a desired compression and deformation to seal the wound site. The skin-contacting surface 330 has a satin finish with a surface roughness in the range of approximately 0.4 pm to 3.0 pm, preferably 0.8 to 2.3 pm and the material of the cushion walls has a hardness in the range of 5 to 80 Shore A, more preferably 30 to 45 Shore A. This allows that there can be minimal applied pneumatic pressure. In fact, as the cushion 325 is pressed lightly against the skin at the wound site, the surface roughness and the resilience of the material cause the visibility to change from translucent to transparent. Indeed, it is envisaged that there may be no need for inflation.

[0120] Referring to Fig. 26, this series of diagrams shows:

[0121] Fig. 26(a), the sheath S is in place.

[0122] Fig. 26(b), the sheath S is partially removed, up to about 2 cm, while ensuring that there is no bleeding. Fig. 26(c), the removal is continued, up to about 3 cm.

[0123] Fig. 26(d), the device 300 is placed across the wound site with the major axis 350 of the cushion 325 extending across the wrist and the cushion in contact with the skin.

[0124] Fig. 26(e), the strap 303 is trimmed at a chosen pair of indentations 303(a) to achieve a desired length. There is typically no need for any inflation, but this can be done via the inflation valve 310 as desired to optimise skin contact to prevent bleeding. The device is secured in place to maintain consistent, gentle pressure. This step ensures a balance between achieving haemostasis and maintaining patient comfort, with the distal radial pulse remaining palpable (patent haemostasis).

[0125] As explained for the example device 100, it is very advantageous that there is no interruption in the line of sight from the lens 320 to the cushion skin-contacting wall. It is also advantageous that there is a visible feature, in this example a crosshairs, in the cushion skin-contacting wall. Moreover, the overall concave configuration of the device assists accurate placement for optimum pressure over the RA and avoidance of slippage or pinching.

[0126] After this step there is continuous monitoring to assess the effectiveness of the applied pressure. Adjustments are minimal but necessary to ensure haemostasis without compromising blood flow to the hand. Monitoring involves checking for cessation of bleeding and ensuring adequate perfusion.

[0127] There may also be gradual pressure release following the initial compression period; the device remains in place for a defined duration, typically 1-4 hours. Gradual loosening or removal of the device minimizes the risk of re-bleeding and allows the vessel to adapt to the decreasing pressure. There may be alternatively or additionally be deflation. Careful observation during this phase ensures that any signs of bleeding are promptly addressed. After achieving complete haemostasis, the device is removed, and a sterile dressing is applied to the puncture site. Patients are advised to avoid strenuous activities and heavy lifting with the affected arm for 24-48 hours to prevent rebleeding. The device may be removed by opening the strap when clinically time to do so, without reopening the wound.

[0128] The devices in normal circumstances do not require inflation and so enhanced patient outcomes are achieved by providing effective haemostasis with improved comfort and reduced risk of complications due to human error (for example, over-inflation). The structure of the cushion maintains the shape and integrity of the seal, providing consistent and controlled compression. This controlled deformation promotes effective haemostasis, as it ensures that the right amount of pressure is applied to stop bleeding without causing undue discomfort or tissue damage. Additionally, the device can be further inflated if additional compression is needed. This inflation capability allows for high precision and control, ensuring that the compression can be finely adjusted to meet the specific needs of the patient.

[0129] The device will aid coagulation of blood at the wound site, to reduce time needed for compression and speed up recovery times. This will minimise clinical intervention.

[0130] As shown in Fig. 27 a coagulation patch 360 / 361 may be attached to the underside surface 330 of the cushion 325, or the cushion of any example described herein. In general, this surface 330 is convex to a small extent, and due to the stiffness of the cushion walls and the surface roughness there is good coagulation, however these layers 360 / 361 may be added for enhanced coagulation.

[0131] The cushion 325 is preferably approximately 12-15 mm across on the major axis 350. It is of electro spun fibres, die cut on a double-sided silicone / acrylic adhesive tape. The materials may be extruded, cast, or moulded. In various examples the cushion of any or some of the following materials:

[0132] Polydioxanone

[0133] Poly-L-lactide

[0134] Poly-D-lactide

[0135] Poly-DL-lactide

[0136] Polyglycolide

[0137] 8-Caprolactone

[0138] Polyethylene glycol

[0139] Copolymers of these materials

[0140] Extruded, cast, moulded sheet

[0141] In addition, collagen and chitosan may also achieve this and in certain cases there may be a blend of synthetic and natural polymers as mentioned.

[0142] Where there is a coagulation layer 160 this may be VT 3104™, or other grades of materials used for wound care. Figs. 28(a) is a perspective view of an alternative cushion 425. This has a rim 427, a distal end rib 440 and a proximal end rib 44, both extending longitudinally, along the major axis. These ribs extend inwardly from walls 428 and 429 of the cushion 425. Fig. 28(b) is cut along the major which extends across the wrist in use (aligned with the strap), Fig. 28(c) is cut away transversely along the minor axis (in the direction of the user’s arm in use). The cushion wall 430 in the central region has a thickness to preferentially increase area (flatten) in the direction of the minor axis for enhanced contact along the artery direction. These drawings also show a lens 431 in the central wall 430. Again, the cushion skin-contacting wall has a visibility feature, in this case a ring-shaped internal protrusion 460.

[0143] The cushion material of the various embodiments has 5 to 80 Shore A hardness with hyperplastic properties, more preferably in the range of 20 to 40 Shore A. The material is soft to touch with good skin to surface sealing properties. Styrene-ethylene-butylene-styrene (SEBS) is also another suitable material for the cushion. Silicone's breathability (moisture permeability and oxygen permeability) is significant improvement on the would site management in addition to comfort, skin-friendliness, adaptability, and durability make it an ideal material for wound care and compression devices. Structure of the cushion will create consistent pressure and is ease of use will create best patient outcomes. Silicone materials allow for breathability, preventing excessive moisture accumulation while maintaining an optimal moist environment conducive to wound healing. This balance helps avoid maceration and dehydration.

[0144] Also, silicone is more flexible and softer than PVC, providing greater comfort for patients, reducing the risk of irritation, pressure sores, and allergic reactions. Its hypoallergenic properties make it suitable for patients with sensitive skin. Also, silicone can be moulded into various shapes and structures to fit the contours of the body better. This adaptability helps maintain consistent pressure across the wound site, enhancing haemostasis and healing. The flexibility and breathability of silicone reduce the risk of skin complications, such as dermatitis and pressure ulcers, which can be associated with less breathable materials like PVC. Further, silicone is highly durable and can often be sterilized and reused, making it a cost-effective option in the long term despite the higher initial cost.

[0145] The cushion surfaces have a surface finish that will indicate intimate contact when contact is made with the wound site resulting in a change in transparency from matt / satin finish to a transparent clear wound site visualisation. This is due to a combination of the low hardness of the cushion material (5 to 80 Shore A) and the surface roughness (0.8 to 2.3 pm Ra preferably). This will give the user of the device an indication that minimum compression has been achieved at the wound site. The surface roughness may be as low as 0.012 pm but is preferably in the range of 0.4 pm to 3.0 pm, and more preferably in the range of 0.8 pm to 2.3 pm.

[0146] The adhesion of dry blood and coagulation of blood at the wound site is expected to be reduced if not eliminated due to the surface energy of the silicone, and the fact that it is classified as hydrophobic. Wound healing is expected to improve due to the permeability of silicone allowing for dehydration of the wound site which is restricted with standard PVC products. Sweating is minimised and dehydration of the wound site will be encouraged, resulting in improved healing time.

[0147] The cushion provides sufficient strength and resilience together with skin engagement to ensure patency haemostasis and good visibility, without need for inflation. The cushion material resilience and breathability (provided by PEO (polyethylene oxide) in one example) help to achieve wound coagulation to speed up wound site healing. It is very advantageous that there is good visibility of the wound site with intimate skin contact of the silicone cushion.

[0148] The cushion, without need for inflation, has a resistance to deformation, whereby a force of about 40 mmHg to 200 mmHg normal to the centre of the contact surface (in use, at wound site), which causes a deformation in the range of 1 mm to 5 mm. This is achieved by the Shore A value of 5 to 80, more preferably 20 to 40 and the shape of the cushion. This helps to avoid need for inflation in most circumstances, avoiding risk of over-pressure and resultant damage to the wound site. It is more preferred that the cushion presents a resistance at the centre of the contact surface in the range of 80 to 160 mmHg, for a 1-3 mm displacement.

[0149] In various examples, it is preferred that a device of the invention has some or all of the following features and advantages:

[0150] The cushion has greater stiffness on one end of the major axis than on the opposed end, to prevent rocking about an axis aligned with the user’s arm at the wrist in use.

[0151] The cushion is elongate with a major axis aligned with the strap longer than a transverse, minor, axis.

[0152] The cushion wall material has hardness in the range of 5 to 80 Shore A.

[0153] The cushion wall has less stiffness in a central region for preferential deformation along the minor axis in use.

[0154] The cushion wall has a skin-contacting surface roughness in the region of 0.4 to 3 pm Ra, preferably 0.8 to 2.3 pm Ra for best optical properties. A combination of the convex lens on the proximal side and the cushion material on the distal side allow excellent visibility of the wound site.

[0155] The cushion material is transparent, with particularly good clarity when pressed against skin due to the surface roughness, giving intimate skin contact. It is particularly advantageous that the cushion has only one layer of material, presenting only one layer between the lens and the skin in use.

[0156] A cushion is attached to a transparent lens which are sealed together (preferably ultrasonically and via a thermoplastic O ring). This provides excellent visualisation due to the transparency of the lens and there being only two layers of material between the users eye line and the wound site.

[0157] The cushion comprises a compliant material which provides both low pressure compression and sealing of the wound site.

[0158] The cushion structure facilitates pre-inflation once the vent plug is removed, however additional inflation is not normally required. Additional inflation and deflation can be achieved by using standard Luer syringe, typically a 5 ml syringe. It is very advantageous that, where in exceptional circumstances inflation is required, it can be performed using a conventional syringe which is inserted into the valve 113 in the same manner as the vent plug was.

[0159] Both the strap and the cushion are permeable to both air and vapour, leading to enhanced haemostasis (coagulation).

[0160] The cushion has a matt / satin finish which becomes clear on adhesion to the patient’s skin / wound site and acts as an indicator to the user that the device is on correctly and at sufficient pressure to prevent bleeding.

[0161] In a particular example the combination of the transparent lens attached to the cushion minimize glare and so it is easier to detect end point haemostasis.

[0162] The strap is made from material which can be easily cut or torn to the required length and has serrated edges to facilitate this, eliminating the requirement for different product sizes. The cushion wall comprises a material which is non-pharmacological and non-biological, which enhances the speed of haemostasis.

[0163] The strap can be easily adjusted while in place to enhance patient comfort and achieve optimal compression and patent haemostasis.

[0164] It will also be appreciated that the device has few parts. Also, it can apply a predictable level of pressure in a uniform manner. It can guarantee a nominal load of for example 150 mmHg at the wound site.

[0165] Moreover, due to the overall concave shape of the body and fasteners it is not susceptible to rocking or slippage in use.

[0166] Components of embodiments can be employed in other embodiments in a manner as would be understood by a person of ordinary skill in the art. For example, all of the features of the material of one device cushion can apply to the other device cushions. The invention is not limited to the embodiments described but may be varied in construction and detail. For example, the strap of any embodiment may be supplied separately from the other components, for attachment at the site of use. In these examples the strap is not bonded to the body, but is trained through a feature in the body in a manner known for any type of watch. It is however preferred that the strap be attached to ensure ease of use and that it is readily available, and it is also preferred that it be bonded to the body at one end to achieve a secure fixation and low profile arrangement.

Claims

Claims1. A haemostatic device comprising: a support body (104) extending in a longitudinal direction from a proximal end (105) to a distal end (106), a strap (103) attached to, or for attachment to, the body (104) to extend in the longitudinal direction, a cushion (125) mounted to the support body, and having an inner wall with a wound sealing and compression contact surface (126, 135, 136) and which is at least partly transparent, and a lens (20) aligned with the wound sealing and compression surface to provide visibility of a wound site via the cushion wall, wherein the cushion (125) is mounted to the support body (104) on an inner side and the lens is mounted on an outer side of the cushion, and the lens (120) and the cushion (125) at least partly enclosing a volume.

2. A device as claimed in claim 1, wherein the cushion (125) is capable of withstanding a pressure in the range of 40 to 200 mmHg for a displacement up to 5 mm at the centre of the contact surface, without need for inflation.

3. A device as claimed in claim 2, wherein the cushion (125) is capable of withstanding a pressure in the range of 80 to 160 mmHg for a displacement up to 3 mm at the centre of the contact surface, without need for inflation.

4. A device as claimed in any preceding claim, wherein the lens (120) is a convex lens.

5. A device as claimed in any preceding claim, wherein the device presents only the lens (120) and the cushion wall (126) for wound visibility in a line of sight through the device.

6. A device of any preceding claim, wherein the cushion (125) is of a material which includes silicone.

7. A device of any preceding claim, wherein the cushion (125) is of a material which has a Shore A hardness in the range of 5 to 80, preferably 20 to 40.

8. A device of any preceding claim, wherein the strap (103) is of a moisture / gas permeable material with a Shore D value in the range of 30 to 45.

9. A device of any preceding claim, wherein the cushion (125) contact surface (135, 136) has a surface roughness in the range of 0.4 um to 3.0 pm Ra.

10. A device of claim 9, wherein said roughness is in the range of 0.8 to 2.3 pm Ra.

11. A device as claimed in any preceding claim, wherein the strap is of a porous material, having an MVTR value in the range of 800 to 4900 g / m2 / 24h, to provide breathability.

12. A device as claimed in any preceding claim, wherein the cushion is of a gas permeable material, having an MVTR value in the range of 100 to 300 g / m2 / 24h, to provide gas and vapour exchange for wound healing.

13. A device of any preceding claim wherein the cushion and the lens enclose a volume in the range of 5 cm3to 15 cm3.

14. A device of claim 13, wherein the cushion and the lens enclose a volume in the range of 5 cm3to 9 cm3.

15. A device as claimed in any preceding claim, wherein the cushion is elongate, with a major axis (350) in the longitudinal direction, and having a proximal wall (130), side walls (128), and a distal wall (131).

16. A device as claimed in any claim 15, wherein the distal wall (131) has a greater stiffness and less deformability than the proximal wall (130).

17. A device of any preceding claim, wherein the cushion has a visible feature (127, 226(a), 326) in a central region of the inner wall.

18. A device as claimed in claim 17, wherein the feature is cross-shaped.

19. A device of any preceding claim, wherein the cushion contact surface (126) has an area in the range of 400 mm2to 750 mm2, and the contact surface is that part of the cushion external surface which extends at an angle greater than 15° from the cushion walls.

20. A device of any preceding claim, wherein the contact surface comprises a raised region (135) having a convex shape which is raised from a surrounding region (136).

21. A device of claim 20, wherein the raised region extends to a distance in the range of 0.5 mm to 2.0 mm from the surrounding region (136).

22. A device of any preceding claim, wherein the body (104) forms a concave shape in the longitudinal direction.

23. A device of claim 22, wherein the support body (104) internal surface median plane (Pl) at its proximal end and its internal surface median plane (P3) at its distal end subtend an angle on the distal side in the range of 10° to 45°.

24. A device of any preceding claim, wherein the body has a strap fastener (106) extending from the distal end of the body, and said fastener internal surface has a median plane (P4) which extends at an angle in the range of 15° to 45° on the distal side relative to the distal end (105) of the body (104).

25. A device of any of claims 15 to 24, wherein the cushion proximal wall (130) has an external surface extending at an angle in the range of 110° to 140° on the proximal and inner side to the plane (Pl) of the body proximal end internal surface.

26. A device of any of claims 15 to 25, wherein the cushion proximal wall (130) extends from the body to a lesser extent than the cushion distal wall (131).

27. A device of any preceding claim, further comprising a conduit (111, 112, 113) in fluid communication with a volume formed by the cushion and the lens, said conduit venting said volume.

28. A device of claim 27, further comprising a vent valve (113) which is normally open, and which allows a user to close the valve so that the volume is closed for use.

29. A device of claim 28, wherein the valve comprises a vent plug (114) for removal from a socket (113) to close the vent.

30. A device of claim 29, wherein the vent plug has a tip with a tubular configuration whereby it performs opening of the valve when inserted in a manner similar to insertion of a syringe tip.

31. A device of any preceding claim, wherein the cushion has greater stiffness at the distal end than on the proximal end.

32. A device of any preceding claim, wherein the cushion (125) has only one layer of material, presenting only one layer between the lens and the skin in use.

33. A device of any preceding claim, wherein the strap comprises serrated edges (303(a)) to allow the strap to be easily cut or tom to a required length.

34. A device of any preceding claim, wherein the cushion comprises a coating (360, 361) of a material which is non-pharmacological and non-biological.

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