Shell Cuff

Abstract

According to one aspect, a shell cuff for use with an actuator cuff and a sensor pad in hemodynamic monitoring is provided, the shell cuff comprising a flexible sheet including a first surface and an opposing second surface, the sheet curving such that a first end of the sheet and an opposing second end of the sheet overlap to form an overlap where a first interface portion of the first surface contacts a second interface portion of the second surface, the sheet configured to tighten upon application of a force to increase a size of the overlap between the first surface and the second surface, the first interface portion comprising a first material and the second interface portion comprising a second material different from the first material.

Description

[Technical field]

[0001] The present invention relates to a shell cuff for use with an actuator cuff and a sensor pad in hemodynamic monitoring, and a kit for hemodynamic monitoring having such a shell cuff. [Background technology]

[0002] Hemodynamic monitoring typically requires invasive techniques or non-invasive monitoring that includes a shell cuff along with an actuator cuff and a sensor pad. The shell cuff is typically coated with a low friction material to reduce friction between parts in sliding contact. Summary of the Invention [Problem to be solved by the invention]

[0003] However, coating with low friction materials is an expensive and time consuming process. [Means for solving the problem]

[0004] According to a first particular aspect, there is provided a shell cuff for use with an actuator cuff and a sensor pad in hemodynamic monitoring, the shell cuff comprising a flexible sheet having a first surface and an opposing second surface, the flexible sheet curving such that a first end of the flexible sheet overlaps with an opposing second end of the flexible sheet to form an overlap where a first interface portion of the first surface interfaces with a second interface portion of the second surface, the flexible sheet being configured to be constricted with an applied force to increase a size of the overlap between the first surface and the second surface, the first interface portion being made from a first material and the second interface portion being made from a second material different from the first material, the first material at the first interface portion (28) extending through more than 20% of a thickness of the flexible sheet and the second material at the second interface portion (30) extending through more than 20% of a thickness of the flexible sheet. The sensor pad is filled with a fluid to measure a hemodynamic parameter such as blood pressure.

[0005] Because the fluid within the sensor pad is incompressible, measurements of hemodynamic parameters at the shell cuff are more accurate and more sensitive.

[0006] Having different materials in contact with each other reduces friction in the shell cuff during use, and having layers of materials in such proportions allows the flexible sheet layers to be easily manufactured by extrusion or injection molding without the need to apply a coating of low friction material, which improves the cost efficiency of manufacturing the shell cuff.

[0007] One of the first surface and the second surface is defined by a remainder and a respective first interface portion or second interface portion, and the respective first interface portion or second interface portion can have a different material than the remainder and the other of the first interface portion and second interface portion.

[0008] The flexible sheet has a first layer having a first material forming a first surface and a second layer having a second material forming a second surface, which allows the flexible sheet to be easily manufactured by extrusion.

[0009] One of the first and second surfaces may have a textured surface at least on the respective first or second interface portion, which may further reduce friction between the first and second interface portions.

[0010] One of the first interface portion and the second interface portion has the compressible material impregnated with silicone oil, the silicone oil being configured to be released upon application of pressure to the compressible material, thereby further reducing friction between the first interface portion and the second interface portion.

[0011] The first material may be HDPE (high density polyethylene) and the second material may be polyamide bonded together with an adhesive layer.

[0012] The first material may comprise a first plastic and the second material may comprise a first plastic modified with PTFE (polytetrafluoroethylene) particles or silicone oil, which may bond particularly well with adhesive layers and provide a low friction bond.

[0013] The first surface may be defined by a first remaining portion and the first interface portion. The second surface may be defined by a second remaining portion and the second interface portion. The first interface portion may be flush with the first remaining portion. The second interface portion may be flush with the second remaining portion. This reduces the likelihood of the first surface getting caught against the second surface when the first and second surfaces contact and slide relative to each other.

[0014] According to a second aspect, there is provided a hemodynamic monitoring kit comprising a shell cuff according to the first aspect, a pressure sensor pad, and an actuator cuff surrounding the shell cuff and configured to inflate to apply pressure to the shell cuff.

[0015] According to a third aspect, there is provided a method of manufacturing a shell cuff according to the first aspect, the method comprising the steps of injection moulding a first material and a second material to form a sheet, and thermoforming the sheet to form the shell cuff.

[0016] According to a fourth aspect, there is provided a method of manufacturing a shell cuff according to the first aspect, the method comprising extruding a first material and a second material to form a sheet having at least two extruded layers, and thermoforming the sheet to form the shell cuff.

[0017] These and other aspects will be apparent from and elucidated with reference to the embodiments described hereinafter. [Brief description of the drawings]

[0018] Exemplary embodiments will now be described, by way of example only, with reference to the following drawings, in which: [Figure 1] FIG. 1 shows a schematic diagram of a hemodynamic monitoring kit. [Diagram 2] FIG. 2 illustrates a schematic of an exemplary shell cuff. [Figure 3A] FIG. 3A illustrates a portion of a further example shell cuff. [Figure 3B] FIG. 3B illustrates a portion of a further example shell cuff. [Figure 4] FIG. 4 is a flow chart of the method steps for manufacturing a shell cuff. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] 1 shows a cross-sectional view of an assembled hemodynamic monitoring kit 10. The hemodynamic monitoring kit 10 includes a sensor pad 12, a shell cuff 20, and an actuator cuff 14.

[0020] The sensor pad 12 includes a sensor configured to sense pressure. The sensor pad 12 may also be filled with a liquid to measure a hemodynamic parameter, such as blood pressure. The shell cuff 20 includes a flexible sheet that is curved to form a tube such that a first end of the flexible sheet and an opposing second end of the flexible sheet overlap to form an overlap 26. Thus, the first and second ends of the flexible sheet are in sliding contact with one another.

[0021] The sensor pad 12 is configured to be received inside a tubular shell cuff 20. The actuator cuff 14 is configured to surround the shell cuff 20 and has a tubular shape with a series of interconnecting chambers that can be inflated to apply pressure to the shell cuff 20.

[0022] In use, the assembled hemodynamic monitoring kit 10 is placed around a user's limb with the sensor pad 12 in contact with the limb, and the actuator cuff 14 inflates and exerts pressure on the shell cuff 20, which distributes pressure evenly around the user's limb. In some examples, the shell cuff may be rolled into a cone shape to accommodate the shape of the user's limb, e.g., arm. Because the shell cuff 20 comprises a flexible sheet, when pressure is exerted by the actuator cuff 14, the shell cuff 20 tightens to form a smaller diameter tube, and the overlap 26 increases in size due to relative slippage between the first and second ends of the flexible sheet. Such slippage can cause friction in the system, which can distort the pressure readings of the sensor pad 12 or cause noise in the pressure measurements. It is therefore desirable to reduce friction as much as possible.

[0023] FIG. 2 illustrates a cross-sectional view of a first exemplary shell cuff 20 along with an enlarged view of an overlap portion 26 of the first exemplary shell cuff 20 .

[0024] The flexible sheet of shell cuff 20, which is rolled into a tubular shape with overlap 26, has a memory for this tubular shape, such that the flexible sheet naturally retains this shape. As explained above, shell cuff 20 can be tightened, for example, by a force applied from actuator cuff 14, to increase the size of overlap 26a, shown in dashed lines in Figure 2. The diameter of tubular shell cuff 20 also decreases when tightened, but for clarity, this is not shown in Figure 2.

[0025] Shell cuff 20 has a first surface 22 and an opposing second surface 24. In this example, first surface 22 is an inner surface of tubular shell cuff 20 and second surface 24 is an outer surface of tubular shell cuff 20. In other words, first surface 22 faces radially inward from shell cuff 20 and second surface 24 faces radially outward from shell cuff 20. In other examples, the first surface may be an outer surface and the second surface may be an inner surface.

[0026] As explained above, the shell cuff 20 has a tubular shape in memory and therefore retains said tubular shape without any external force. When no external force is applied to the shell cuff 20, the first side 22 is defined by a first interface portion 28 and a first remaining portion 29, and the second side 24 is defined by a second interface portion 30 and a second remaining portion 31, where the first interface portion 28 interfaces with the second interface portion 30 at the overlap portion 26. The lines defining the boundaries between the respective interface portions and the remaining portions on the first side 22 and the second side 24 are shown as dashed lines cutting the flexible sheet. Due to the curved tubular shape of the shell cuff 20, the first side 22 interfaces with the second side 24 at the overlap portion 26. As the shell cuff 20 is tightened with an applied force, the overlap increases so that the first interface portion 28 and a portion of the first remaining portion 29 interface with the second interface portion 30 and a portion of the second remaining portion 31 .

[0027] In this example, the flexible sheet of shell cuff 20 is formed from a first material 32 in the form of a first layer and a second material 34 in the form of a second layer that are bonded together with a layer of adhesive 36. In this example, first material 32 forms first side 22 of shell cuff 20 and second material 34 forms second side 24 of shell cuff 20. In other examples, the first layer and the second layer may be bonded together without the use of an adhesive.

[0028] In this example, the first material comprises HDPE and the second material comprises polyamide. In another example, the first material can comprise polypropylene and the second material can comprise polypropylene modified with PTFE particles or silicone oil. In yet another example, one of the first or second material can comprise any plastic and the other of the first or second material can comprise a plastic modified with PTFE particles or silicone oil or any other low friction material. The first and second materials can comprise any suitable material, provided that the material defining at least the first interface is different from the material defining the second interface.

[0029] The use of different materials for the different layers ensures that the first interface portion 28 and the second interface portion 30 have different materials. The first interface portion 28 and the second interface portion 30 having different materials ensures that when there is sliding contact between the surfaces of the shell cuff 20, the van der Waals forces are reduced, thereby reducing friction between said surfaces without the need for additional coatings.

[0030] Figure 3A illustrates a cross-sectional view of the overlapping portion 126 of the second exemplary shell cuff 120. Figure 3B illustrates a cross-sectional view of the overlapping portion 226 of the third exemplary shell cuff 220.

[0031] The second exemplary shell cuff 120 is similar to the first exemplary shell cuff 20 in having a first side 22 and an opposing second side 24, differing only in the configuration of the flexible sheet of the shell cuff 120. In this example, the first side 22 is made from a first material and the second interface portion 30 is made from a second material. The second remainder portion 31 is made from the first material such that only the second interface portion 30 of the second side 24 comprises the second material. Thus, in this example, the entire flexible sheet comprises the first material, except for the portion of said flexible sheet defining the second interface portion 30 of the second side 24.

[0032] The second interface portion 30 of the second surface 24 is flush with the second remaining portion 31 of the second surface 24. In some examples, the second interface portion may be offset from the second remaining portion. In this example, the second material extends to at least one third of the thickness of the flexible sheet. In other examples, the second material may extend to more than 20% of the thickness of the flexible sheet, up to 50% of the thickness, or the entire thickness of the flexible sheet at the second interface portion. In other words, the flexible sheet at the second interface portion may have a thickness such that at least 20% of its thickness comprises the second material (i.e., the ratio of the thickness of the second material to the thickness of the entire flexible sheet at the second interface portion is at least 20%). This can also be applied to the first material at the first interface portion. This relates to a minimum thickness of the first and second materials of 1.5 mm. This minimum thickness percentage also allows the layers of the flexible sheet to be more easily extruded or injection molded, as will be explained with reference to FIG.

[0033] In some examples, the first material and the second material can comprise HDPE, LDPE (low density polyethylene), polyamide, or any plastic, where the first material and the second material are different such that at least the first interface portion 28 comprises a different material than the second interface portion 30. In examples where the second material is a compressible plastic impregnated with silicone oil, application of pressure can release the silicone oil, thereby forming a low friction layer of oil between the first interface portion 28 and the second interface portion 30.

[0034] The third exemplary shell cuff 220 is similar to the second exemplary shell cuff 120, except that the second interface portion 30 has a textured surface that can reduce the contact surface area between the first interface portion 28 and the second interface portion 30 during use, thereby further reducing friction between the first surface 22 and the second surface 24.

[0035] Although the shell cuff 120 in FIGS. 3A-3B has been described as having a first surface and a second remaining portion with a first material and a second interface portion with a second material, in other examples, the second remaining portion can have a third material different from the first and second materials. For example, the flexible sheet can have two layers of a first material and a third material, and only the second interface portion can have the second material. In a further example, the second material can extend beyond the second interface portion to a portion of the second remaining portion to further reduce friction even when a force is applied to tighten the shell cuff. In yet another example, the first interface portion can have a second material, and the second surface and the first remaining portion can have the first material and / or the third material.

[0036] FIG. 4 is a flow chart illustrating the steps of a method of forming the shell cuff 20, 120, 220 described with reference to any of the preceding FIGS.

[0037] At block 402, the method includes extruding a first material and a second material to form a flexible sheet of a shell cuff having at least two layers of material, such as the flexible sheet of the first exemplary shell cuff 20 described with reference to FIG. 2.

[0038] At block 404, the method includes injection molding a first material and a second material to form a sheet, as described in any of the embodiments described herein.

[0039] At block 406, the method includes thermoforming the sheet made at either block 402 or block 404 to form the shell cuff 20, 120, 220 as described in any of the embodiments described herein.

[0040] Injection molding the flexible sheet to form shell cuffs 20, 120, 220 allows the texturing to be added to either the first or second side of the flexible sheet, allowing a portion of a side to have a different material than the remainder of that side, as described in the second and third exemplary shell cuffs. Both extruding and injection molding materials to form the shell cuffs with two different materials at the overlapping portion of the shell cuff means that this is accomplished without the need for a coating on the flexible sheet, thereby providing a cost-effective method of manufacturing shell cuffs with reduced friction.

[0041] Variations to the disclosed embodiments can be understood and implemented by those skilled in the art in implementing the principles and techniques described herein, from a study of the drawings, the disclosure and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, nor does it exclude a plurality of them if a plurality is not stated. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain means are recited in mutually different dependent claims does not indicate that a combination of these means cannot be used to advantage. A computer program may be stored or distributed on a suitable medium, for example an optical storage medium or a solid-state medium, supplied together with or as part of other hardware, but may also be distributed in other forms, for example via the Internet or other wired or wireless telecommunication systems. Any reference signs in the claims should not be interpreted as limiting the scope thereof.

Claims

1. 1. A shell cuff for use with an actuator cuff and a sensor pad in hemodynamic monitoring, said shell cuff comprising: a flexible sheet having a first surface and an opposing second surface, the flexible sheet being curved such that a first end of the flexible sheet and an opposing second end of the flexible sheet overlap to form an overlap where a first joint portion of the first surface joins a second joint portion of the second surface; the second surface is defined by a second remaining portion and the second joining portion, the second joining portion being flush with the second remaining portion; the flexible sheet is configured to be tightened upon application of a force to increase a size of the overlap between the first surface and the second surface; the first interface portion is made from the first material and the second interface portion is made from a second material different from the first material, the first material at the first interface portion extends through more than 20% of the thickness of the flexible sheet, and the second material at the second interface portion extends through more than 20% of the thickness of the flexible sheet; The sensor pad is filled with a fluid to measure a hemodynamic parameter. Shell cuff.

2. the first surface is defined by a first remaining portion and the first joining portion; the first joint portion or the second joint portion has a material different from the remaining portion and the other of the first joint portion and the second joint portion; The shell cuff of claim 1.

3. The flexible sheet is a first layer having the first material forming the first surface; and a second layer having the second material forming the second surface; 2. The shell cuff of claim 1, having

4. one of the first side and the second side has a textured surface on at least the first interface portion or the second interface portion; The shell cuff of claim 1.

5. 2. The shell cuff of claim 1, wherein one of the first interface portion and the second interface portion comprises a compressible material impregnated with silicone oil, the silicone oil being configured to be released upon application of pressure to the compressible material.

6. 10. The shell cuff of claim 1, wherein the first material is high density polyethylene (HDPE) and the second material is polyamide bonded together with an adhesive layer.

7. 10. The shell cuff of claim 1, wherein the first material comprises a first plastic and the second material comprises the first plastic modified with polytetrafluoroethylene (PTFE) particles or silicone oil.

8. the first surface is defined by a first remaining portion and the first joining portion; the first interface portion is flush with the first remainder portion; The shell cuff of claim 1.

9. The shell cuff according to claim 1, Pressure sensor pads, and an actuator cuff that surrounds the shell cuff and is configured to inflate to apply pressure to the shell cuff; A hemodynamic monitoring kit comprising:

10. 10. The method of manufacturing a shell cuff according to claim 1, said method comprising: injection molding the first material and the second material to form a sheet; and thermoforming said sheet to form said shell cuff The method comprising:

11. 4. A method of manufacturing a shell cuff according to claim 3, said method comprising: extruding the first material and the second material to form a sheet having at least two extruded layers; and thermoforming said sheet to form said shell cuff The method comprising:

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