MEDICAL DEVICE FOR VISUALLY DISPLAYING AN INJECTION PRESSURE OF A FLUID

Abstract

A medical device and kit for visually displaying an injection pressure of a fluid, The device has a fluid path for the fluid and includes a piezochromic material which, under the action of a pressure of < 100 bar, displays a piezochromic color change that is perceptible to the human eye.

Claims

1. A medical device for visually displaying an injection pressure of a fluid, the medical device comprising a fluid path for the fluid and a piezochromic material which exhibits a piezochromic color change when exposed to a pressure of < 100 bar.

2. The medical device according to claim 1, wherein the piezochromic material exhibits the piezochromic color change when exposed to a pressure from 1 bar to 3 bar.

3. The medical device according to claim 1, wherein the piezochromic material exhibits the piezochromic color change within a period of < 1 s.

4. The medical device according to claim 1, wherein the piezochromic material comprises a matrix composed of at least one polymer and/or copolymer, at least one liquid crystal and at least one optically active substance, wherein the optically active substance is distributed in the matrix.

5. The medical device according to claim 4, wherein the at least one liquid crystal is selected from the group consisting of N-(p-ethoxybenzylidene)-p-n-butylaniline, N-(p-methoxybenzylidene)-p-n-butylaniline, 4-alkylphenyl 4-N-alkylbenzoate, cholesteryl benzoate, cholesterol, tolan, alkanoic acids, stilbene, azobenzene, 4-phenylcinnamic acid, p-terphenyl, 1,2-bisbenzoethylene, mixtures of alkylcyanobiphenyls and alkoxycyanobiphenyls, and mixtures of at least two of the aforementioned liquid crystals.

6. The medical device according to claim 4, wherein the at least one optically active substance is selected from the group consisting of 2-octyl 4-[[4-(hexoyl)benzoyl]oxy]benzoate, cholesteryl derivatives and mixtures thereof.

7. The medical device according to claim 4, wherein the polymer and/or copolymer is a poly(meth)acrylate or a copoly(meth)acrylate that has been synthesized from at least one monofunctional monomer and/or at least one multifunctional crosslinker.

8. The medical device according to claim 7, wherein the monomer is selected from the group consisting of benzyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, methoxyethyl (meth)acrylate, octadecyl (meth)acrylate and mixtures of at least two of the aforementioned monomers and/or the crosslinker is selected from the group consisting of 1,4-butanediol di(meth)acrylate, polyethylene glycol diacrylate, polyethylene glycol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, bisphenol A glycerolate (1 glycerol/phenol) diacrylate and mixtures of at least two of the aforementioned crosslinkers.

9. The medical device according to claim 1, wherein the piezochromic material is contained in a housing wall of the medical device that surrounds the fluid path.

10. The medical device according to claim 9, wherein the housing wall comprises at least one multilayer wall section, wherein an intermediate layer of the at least one multilayer wall section comprises the piezochromic material or consists of the piezochromic material.

11. The medical device according to claim 10, wherein the at least one multilayer wall section also comprises an inner layer which covers the intermediate layer on a side facing the fluid path and which comprises a biocompatible material or consists of the biocompatible material.

12. The medical device according to claim 11, wherein the biocompatible material is selected from the group consisting of polyethylene terephthalate, polyetheretherketone, polypropylene, polyphenylsulfone, polyoxymethylene and mixtures of at least two of the aforementioned biocompatible materials.

13. The medical device according to claim 10, wherein the at least one multilayer wall section also comprises an outer layer which covers the intermediate layer on a side facing away from the fluid path and which comprises a transparent material or consists of the transparent material.

14. The medical device according to claim 13, wherein the transparent material is selected from the group consisting of polycarbonate, polymethyl methacrylate, polyurethane and mixtures of at least two of the aforementioned transparent materials.

15. The medical device according to claim 9, wherein the housing wall is a wall of a syringe body of the medical device.

16. The medical device according to claim 9, wherein the housing wall is a lateral wall of a syringe body of the medical device.

17. The medical device according to claim 9, wherein the housing wall is an end wall of a syringe body of the medical device.

18. The medical device according to claim 9, wherein the housing wall is a wall of an outlet nozzle of a syringe body of the medical device.

19. The medical device according to claim 18, wherein the outlet nozzle comprises a branch having a closed end, wherein the piezochromic material is contained in the closed end.

20. The medical device according to claim 1, wherein the piezochromic material is contained in a stopper of a syringe plunger of the medical device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0073] The following is shown schematically in the figures:

[0074] FIG. 1: one embodiment of a medical device according to the invention,

[0075] FIG. 2: a cross-sectional representation of a further embodiment of a medical device according to the invention,

[0076] FIG. 3: a plan view of the embodiment of a medical device according to the invention depicted in FIG. 2,

[0077] FIG. 4: a detailed view of a housing wall of a further embodiment of a medical device according to the invention,

[0078] FIG. 5: a plan view of a housing wall of a further embodiment of a medical device according to the invention,

[0079] FIG. 6: a further embodiment of a medical device according to the invention,

[0080] FIG. 7: a further embodiment of a medical device according to the invention,

[0081] FIG. 8: a further embodiment of a medical device according to the invention, and

[0082] FIG. 9 a further embodiment of a medical device according to the invention.

DETAILED DESCRIPTION

[0083] FIG. 1 shows schematically one embodiment of a medical device 1 according to the invention for visually or optically displaying an injection pressure, in particular an injection threshold pressure, of an anesthetic when performing peripheral regional anesthesia.

[0084] The medical device 1 is connected between an injection tube 2 and a syringe 3. To this end, the medical device advantageously comprises a connector mechanism 4 for connecting the medical device 1 to the injection tube 2 and a further connector mechanism 5 for connecting the medical device 1 to the syringe 3. The connector mechanisms 4 and 5 can, for example, each be in the form of Luer-Lock connectors.

[0085] The syringe 3 has a cavity (lumen) 6 which has been filled with an anesthetic. A cannula 7 is attached to a distal end of the injection tube 2, i.e., to an end remote from the center of the body of a user, in this case an anesthesiologist.

[0086] The medical device 1 comprises a fluid path 8 for the anesthetic and a piezochromic material. The piezochromic material preferably exhibits a piezochromic color change perceptible to the human eye when exposed to a pressure of < 10 bar, preferably < 5 bar, particularly preferably from 1 bar to 3 bar. The piezochromic material can be, in particular, a piezochromic plastic or a piezochromic composition. Preferably, the piezochromic material comprises a matrix composed of at least one polymer and/or copolymer, at least one liquid crystal and at least one optically active substance, in particular a chirally optically active substance. The optically active substance is preferably distributed in the matrix.

[0087] The aforementioned polymer can be, for example, a crosslinked polymethacrylate. The aforementioned copolymer can be, for example, a crosslinked copolymethacrylate. The at least one liquid crystal can be, for example, a liquid-crystal mixture of four different alkylcyanobiphenyl derivatives and one alkoxycyanobiphenyl derivative. The optically active substance can be, for example, the substance S-811, i.e., 4-(4-hexyloxybenzoyloxy)benzoate, cholesteryl derivatives and/or mixtures thereof.

[0088] To perform the peripheral regional anesthesia, the tip 9 of the cannula 7 is brought as close as possible to a nerve 11 located in a peripheral tissue region 10, for example under ultrasound guidance. The nerve 11 is depicted in cross section in FIG. 1. In addition, the anesthesiologist checks the correct position of the cannula tip 9 by carefully increasing the force on a plunger 12 of the syringe 3. If the tip 9 of the cannula 7 is directly on the nerve 11 or even in the nerve 11, the opening injection pressure, which is in principle static, rises to a defined value, generally to a value greater than 1.034 bar (> 15 psi). The static pressure of the anesthetic, which is the same throughout the fluid path 8 of the medical device 1, can, now, be shown optically via the piezochromic material of the medical device 1. This is achieved by the fluid path 8, which runs through the medical device 1, being guided past a housing wall 13, i.e., past a wall 13 of a housing 14 of the medical device 1, said housing wall 13 comprising in the thickness direction thereof at least one wall section 15 which is composed of multiple layers, in particular three layers, and contains the piezochromic material. Preferably, the wall section 15 comprises an intermediate layer which has been coated with an inner layer on a side facing the fluid path 8 and with an outer layer on a side facing away from the fluid path 8. Preferably, the intermediate layer comprises the piezochromic material or consists of the piezochromic material. The inner layer preferably comprises a biocompatible material, preferably for protection of the piezochromic material from the fluid, or consists of such a material. The biocompatible material can be, for example, polyethylene terephthalate, polyetheretherketone, polypropylene, polyphenylsulfone or polyoxymethylene. The outer layer preferably comprises a transparent material or consists of such a material. The transparent material can be, for example, polycarbonate, polymethyl methacrylate or polyurethane. Conveniently, the inner layer is in direct contact with the fluid path 8 of the medical device 1, whereas the outer layer conveniently forms part of the exterior of the housing 14 of the medical device 1. The outer layer can be, in particular, designed as a screen or display.

[0089] The piezochromic material changes its color when the injection pressure is increased to a defined value dependent on the composition of the piezochromic material. The color change can occur reversibly or irreversibly. Advantageously, the threshold pressure of the injection pressure can be adjusted very accurately and in particular reproducibly via the composition of the piezochromic material. In this way, pressures which reach or exceed a defined pressure can be seen optically. Owing to the abovementioned transparent outer layer, the color change of the piezochromic material is outwardly visible. As a result, the anesthesiologist will detect that he has positioned the cannula tip 9 either too close to the nerve to be blocked or even in said nerve, and can appropriately correct the position of the cannula tip 9. As a result, damage to the nerve 11 can be avoided with particular advantage.

[0090] FIG. 2 shows schematically a cross-sectional view of a further embodiment of a medical device 1 according to the invention for visually or optically displaying an injection pressure, in particular an injection threshold pressure, of a fluid, for example an anesthetic or an anesthetic-containing liquid.

[0091] The medical device 1 comprises a fluid path 8 which is surrounded by a housing wall 13, i.e., a wall 13 of a housing 14 of the medical device 1. The wall 11 comprises a wall section 15. The wall section 15 has a trilayer structure composed of an inner layer 15a, an intermediate layer 15b and an outer layer 15c. The intermediate layer 15b comprises a piezochromic material or consists of such a material. The inner layer 15a comprises a biocompatible material for protection of the piezochromic material from direct contact with the fluid or consists of such a material. The outer layer 15c comprises a transparent material or consists of such a material. Regarding further features and advantages of the piezochromic material, biocompatible material and transparent material, reference is made to the foregoing description, in particular to the features and advantages mentioned in the figure description for FIG. 1.

[0092] The inner layer 15a covers the intermediate layer 15b, preferably directly, on a side facing the fluid path 8. The inner layer 15a is preferably in direct contact with the fluid path 8. In contrast, the outer layer 15c covers the intermediate layer 15b, preferably directly, on a side facing away from the fluid path 8. Preferably, the outer layer 15c forms part of the exterior of the housing 14 of the medical device 1.

[0093] The housing 14 of the medical device 1 can further comprise a reinforcement, in particular a reinforcing rib, 16, in particular in the region of the wall section 15. Furthermore, the medical device 1 can comprise a web 17 formed on the inside toward the wall section 15. Preferably, the web 17 is part of a part 18 of the housing 14 that is arranged opposite the wall section 15. The web 17 can advantageously prevent the formation of air bubbles when injecting the fluid and guide the fluid flow directly past the wall section 15 and thus past the piezochromic material present therein. Furthermore, a reduction in the dead space volume is advantageously realizable as a result.

[0094] For further functionality of the medical device 1 shown schematically in FIG. 2, full reference is made to the foregoing description, in particular to the figure description for FIG. 1. The discussion there in this respect applies correspondingly.

[0095] FIG. 3 shows schematically a plan view of the embodiment of a medical device 1 according to the invention depicted in FIG. 2.

[0096] A color change of the piezochromic material, and thus pressures which reach or exceed an injection threshold pressure when injecting the fluid, is optically detectable via the transparent outer layer 15c located on the exterior of the housing 14. If necessary, an anesthesiologist can correct the position of a cannula tip, especially when performing a peripheral regional anesthetic procedure.

[0097] FIG. 4 shows schematically the detailed view of a housing wall 13 of a further embodiment of a medical device according to the invention for visually or optically displaying an injection pressure, in particular an injection threshold pressure, of a fluid, for example an anesthetic or an anesthetic-containing liquid.

[0098] The housing wall 13 comprises a wall section 15. It has, in the thickness direction of the housing wall 13, a trilayer structure composed of an inner layer 15a, an intermediate layer 15b and an outer layer 15c. The intermediate layer 15b consists of multiple intermediate layer sections which are arranged next to one another, preferably directly next to one another, in the longitudinal direction of the housing wall. Preferably, the intermediate layer sections each comprise a different piezochromic material or each consist of a different piezochromic material. As a result, different injection threshold pressures can be advantageously visualized. For example, the intermediate layer 15b, as depicted in FIG. 4, can consist of three such intermediate layer sections 15b.sub.1, 15b.sub.2 and 15b.sub.3. For example, the piezochromic materials for the intermediate layer sections 15bi, 15b.sub.2 and 15b.sub.3 can be chosen such that the piezochromic material of the intermediate layer section 15b.sub.1 exhibits a color change when exposed to a pressure ≥ 0.69 bar (≥ 10 psi), the piezochromic material of the intermediate layer section 15b.sub.2 exhibits a color change when exposed to a pressure ≥ 1.03 bar (≥ 15 psi) and the piezochromic material of the intermediate layer section 15b.sub.3 exhibits a color change when exposed to a pressure ≥ 1.38 bar (≥ 20 psi). Regarding further suitable piezochromic materials, reference is made to the piezochromic materials already mentioned in the foregoing description, in particular in the figure description for FIG. 1.

[0099] On a side facing a fluid path, the intermediate layer 15b is covered, preferably directly and completely, by the inner layer 15a. Preferably, the inner layer 15a is in direct contact with the fluid path. The inner layer 15a comprises a biocompatible material for protection of the piezochromic materials of the intermediate layer 15b from direct contact with a fluid which is conveyed through the fluid path, or consists of such a material. Regarding suitable biocompatible materials, reference is made to the biocompatible materials already mentioned in the foregoing description, in particular in the figure description for FIG. 1.

[0100] The outer layer 15c covers, preferably directly and completely, the intermediate layer 15b preferably on a side facing away from a fluid path. Preferably, the outer layer 15c forms part of the exterior of the housing 14 of the medical device 1. The inner layer 15c comprises a transparent material or consists of such a material. As a result, a color change of the piezochromic materials will be optically detectable for a user, in particular an anesthesiologist. The outer layer can be, in particular, designed as a screen or display.

[0101] Regarding suitable transparent materials, reference is made to the transparent materials already mentioned in the foregoing description, in particular in the figure description for FIG. 1.

[0102] FIG. 5 shows schematically a plan view of a housing wall of a further embodiment of a medical device 1 according to the invention.

[0103] The medical device 1 comprises a housing 14 having a housing wall 13. The housing wall 13 comprises a wall section 15 which is widened in the thickness direction of the housing wall compared to the rest of the housing wall. The wall section 15 has the structure described in the figure description for FIG. 4. Via the outer layer 15c, which can be in particular designed as a screen or display, it is possible to visualize the color changes caused by the piezochromic materials of the intermediate layer sections 15b.sub.1, 15b.sub.2 and 15b.sub.3 when exposed to different pressures.

[0104] FIG. 6 shows schematically a further embodiment of a medical device 1 according to the invention for visually or optically displaying an injection pressure, in particular an injection threshold pressure, of a fluid, for example an anesthetic or an anesthetic-containing liquid.

[0105] The medical device 1 is designed as a syringe having a syringe body 19 having a preferably conical or cylindrical outlet nozzle 21. The syringe body 19 is preferably cylindrical, in particular circular-cylindrical. The medical device 1 comprises a fluid path 8 which is formed both by the cavity of the syringe body 19 and by the cavity of the outlet nozzle 21.

[0106] Furthermore, the syringe body 19 comprises a lateral wall 13 having a wall section 15. The wall section 15 has, in the thickness direction of the lateral wall, a trilayer structure composed of an inner layer, intermediate layer and outer layer. The inner layer covers the intermediate layer on a side facing the fluid path 8, whereas the outer layer covers the intermediate layer on a side facing away from the fluid path 8. Preferably, the inner layer is in direct contact with the fluid path 8. Preferably, the outer layer forms part of the exterior of the syringe body 19. The intermediate layer comprises a piezochromic material or consists of a piezochromic material. The inner layer comprises a biocompatible material for protection of the piezochromic material from direct contact with the fluid or consists of such a biocompatible material. The outer layer comprises a transparent material or consists of a transparent material. Regarding suitable piezochromic materials, biocompatible materials and transparent materials and regarding the functionality of the medical device 1, reference is made to the foregoing description, in particular to the figure description for FIG. 1.

[0107] FIG. 7 shows schematically a further embodiment of a medical device 1 according to the invention for visually or optically displaying an injection pressure, in particular an injection threshold pressure, of a fluid, for example an anesthetic or an anesthetic-containing liquid.

[0108] The medical device 1 is (likewise) designed as a syringe having a syringe body 19. The syringe body 19 is preferably cylindrical, in particular circular-cylindrical. The medical device 1 comprises a fluid path 8 which is formed both by the cavity of the syringe body 19 and by the cavity of the outlet nozzle 21.

[0109] Furthermore, the syringe body 19 comprises an end wall 13 having a trilayer structure composed of an inner layer, intermediate layer and outer layer. The end wall surrounds an outlet opening 20 which opens into a conical or cylindrical outlet nozzle 21 of the syringe body 19.

[0110] Regarding further features and advantages and regarding the further functionality of the medical device shown in FIG. 7, in particular regarding the aforementioned intermediate layer, inner layer and outer layer, full reference is made to the foregoing description, in particular to the figure descriptions for FIGS. 1 and 6.

[0111] FIG. 8 shows a further embodiment of a medical device 1 according to the invention for visually or optically displaying an injection pressure, in particular an injection threshold pressure, of a fluid, for example an anesthetic or an anesthetic-containing liquid.

[0112] The medical device 1 is (likewise) designed as a syringe and comprises a syringe body 19 having a preferably conical or cylindrical outlet nozzle 21 and a syringe plunger 22. The syringe body 19 is preferably cylindrical, in particular circular-cylindrical. The syringe plunger 22 comprises a rod 23, a head 24 and a stopper 25. The medical device 1 comprises a fluid path 8 which is formed both by the cavity of the syringe body 19 and by the cavity of the outlet nozzle 21.

[0113] The outlet nozzle 21 has a branch or bifurcation 26 having a closed end 15. The closed end 15 thus forms a branched-off or bifurcated wall section of the syringe body 19.

[0114] Preferably, the closed end or the branched-off or bifurcated wall section 15 has a trilayer structure composed of an inner layer 15a, intermediate layer 15b and outer layer 15c.

[0115] Regarding further features and advantages and regarding the further functionality of the medical device shown in FIG. 8, in particular regarding the aforementioned intermediate layer, inner layer and outer layer, full reference is made to the foregoing description, in particular to the figure descriptions for FIGS. 1 and 6.

[0116] FIG. 9 shows a further embodiment of a medical device 1 according to the invention for visually or optically displaying an injection pressure, in particular an injection threshold pressure, of a fluid, for example an anesthetic or an anesthetic-containing liquid.

[0117] The medical device 1 is (likewise) designed as a syringe and has a syringe body 19 having a preferably conical or cylindrical outlet nozzle 21 and a syringe plunger 22 having a rod 23, a head 24 and a stopper 25. The medical device 1 comprises a fluid path 8 which is formed both by the cavity of the syringe body 19 and by the cavity of the outlet nozzle 21.

[0118] The stopper 25 of the syringe plunger 22 comprises a layer 25b which is covered by a layer 25a, said layer 25a forming part of the exterior of the stopper 25. The layer 25b comprises a piezochromic material or consists of such a material. The layer 25a comprises a transparent material or consists of a transparent material. In this way, a color change of the piezochromic material can be visualized for a user, in particular a physician.

[0119] Regarding further features and advantages and regarding the further functionality of the medical device shown in FIG. 8, in particular regarding the aforementioned piezochromic material and the aforementioned transparent material, full reference is made to the foregoing description, in particular to the figure descriptions for FIGS. 1 and 6.

EXAMPLE SECTION

1. Preparation of a Piezochromic Material According to the Present Invention (Including an Appropriately Assembled Film)

1.1 Preparation of a Mixture of a Liquid Crystal and a Chirally Optically Active Substance

[0120] The optically active substance S-811 was admixed at a proportion by weight of 22% to a liquid crystal mixture E5 (mixture consisting of four alkylcyanobiphenyl derivative components and one alkoxycyanobiphenyl derivative component). The mixture was heated above the clearing point of the E5 component to 58° C. and then cooled back to room temperature.

1.2 Preparation of a Mixture of a Monofunctional Methacrylate Monomer and a Crosslinker

[0121] 34% by weight of DDA was doped into the monomer benzyl methacrylate. Thereafter, the mixture was heated to 60° C. for 25 min.

[0122] The mixtures prepared according to 1.1 and 1.2 were mixed in a ratio of 1:2.4 at a temperature between 50° C. and 55° C. Finally, 0.2% by weight of Genocure LTM polymerization initiator was doped in. The piezochromic material was assembled with a layer thickness of 25 .Math.m between two polypropylene films, which were each 15 .Math.m thick and which were polyamide-coated (less than 1 .Math.m), and polymerized under UV light for 15 min. This yielded a red-reflecting film which was easily movable and flexible and became a green-reflecting film to the eye upon an increase in pressure of 0.4 bar. If the pressure was increased again by 0.7 bar, the color turned blue. The process was reversible. The color change of the film occurred in less than 1 s.

2. Preparation of a Further Piezochromic Material According to the Present Invention (Including an Appropriately Assembled Film)

2.1 Preparation of a Mixture of a Liquid Crystal and a Chirally Optically Active Substance

[0123] The optically active substance cholesteryl oleyl carbonate was doped at 27% by weight into the liquid crystal EBBA. The mixture was heated above the clearing point of EBBA to 52° C.

2.2 Preparation of a Mixture of a Monofunctional Acrylate Monomer and a Crosslinker

[0124] 28% by weight of the crosslinker polyethylene glycol diacrylate, M70, was doped into the monomer octadecyl acrylate, and the mixture was heated to 55° C.

[0125] The mixtures prepared according to 2.1 and 2.2 were mixed in a ratio of 1:1.9 at a temperature between 45° C. and 50° C. The polymerization initiator used was 0.45% LOCERIN™ (BASF). The piezochromic material was assembled with a layer thickness of 30 .Math.m between two films available under the trademark ZEONORFILM™, each 12 .Math.m thick. Both ZEONORFILM™ films were provided with a maleic anhydride-styrene copolymer orientation layer (< 1 .Math.m). The system was polymerized in UV light for 20 min. Thereafter, the ZEONORFILM™ films could then be easily removed. This yielded a 30 .Math.m thick piezochromic layer. It changed its color from red to blue in less than 1 s upon an increase in pressure of 0.8 bar.