Anesthesia endotracheal tube end anti-mucosa-injury protection assembly

Abstract

This invention discloses a protective component for preventing mucosal damage at the tip of an anesthetic endotracheal tube, comprising a flexible protective tip and a gradually transitioning support sleeve connected axially to the proximal end of the flexible protective tip. This protective component is fitted onto the insertion end of the endotracheal tube. Its key feature is that the flexible protective tip is rounded and bullet-shaped. Through an integrated structural design of "flexible tip + gradually transitioning + sustained drug release + multiple fixation," it covers the entire operational cycle of intubation, placement, and extubation. The rounded and bullet-shaped flexible protective tip is wrapped with Shore A25 soft silicone to replace the original sharp edge, dispersing contact pressure and preventing punctures or scratches to the vocal cords and airway mucosa during intubation. The gradually changing, smooth conical transition support sleeve completely eliminates the diameter step between the tube tip and the tube body, solving the problems of scratching and jamming at the glottis of traditional tubes, and tissue contusion.

Description

Technical Field

[0001] This invention relates to the field of endotracheal intubation technology, specifically to a protective component for preventing mucosal damage at the tip of an anesthetic endotracheal tube. Background Technology

[0002] Endotracheal intubation is a core clinical procedure for establishing an artificial airway and ensuring patient ventilation, and it is widely used in general anesthesia, ICU respiratory support, and emergency resuscitation. The rigid structure and high surface friction of the endotracheal tube insertion end are the core direct causes of acute and chronic airway mucosal damage, and also a key problem that current clinical protection measures have not completely solved.

[0003] Currently, the mainstream clinical endotracheal tubes are made of rigid PVC and polyurethane as the tube body material. Their insertion ends generally exhibit three structural characteristics: first, the tube tip edge is relatively sharp, lacking a flexible transition; second, there is a distinct diameter step of 0.2–0.5 mm between the tip and the tube body; and third, the surface friction resistance of the end material is high, with a wet dynamic friction coefficient often greater than 0.15. These characteristics work together to continuously cause mucosal damage throughout the clinical process: during insertion, the sharp edges of the tip easily scrape the vocal cords and subglottic mucosa, and the diameter step easily snags on the vocal cord tissue and the lower edge of the cricoid cartilage, leading to obstruction and tissue contusion. The high-friction surface further exacerbates wear and even produces a "scratching-slipping" effect, causing local high shear force damage; during indwelling, the tube tip repeatedly rubs and compresses the tracheal wall with the patient's breathing, coughing, and body movements, causing short-term mucosal edema and postoperative hoarseness, and long-term indwelling for more than 72 hours easily induces serious complications such as mucosal ulcers and granulation tissue hyperplasia. Summary of the Invention

[0004] The purpose of this invention is to provide a protective component for the end of anesthesia endotracheal tube to prevent mucosal damage, thereby solving the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A protective component for preventing mucosal damage at the tip of an anesthetic endotracheal tube includes a flexible protective tip and a gradually transitioning support sleeve connected axially along the tube to the proximal end of the flexible protective tip. The protective component is fitted onto the insertion end of the endotracheal tube body. The flexible protective tip is characterized by being blunt and bullet-shaped, with a smooth spherical dome at the distal end that completely covers the outer wall of the endotracheal tube body tip. After covering, the total outer diameter is consistent with the outer diameter of the endotracheal tube body. The inner wall of the flexible protective tip is provided with an interference fit that engages with a pre-set annular flange at the tip of the endotracheal tube body. The annular groove has a side ventilation hole on its side wall that aligns with the Murphy hole of the endotracheal tube body. The side ventilation hole has a rounded chamfer on its edge. The material hardness of the gradient transition support sleeve gradually increases from the distal end to the proximal end along the axial direction. The outer wall is a smooth conical surface, and the inner wall has circumferentially distributed anti-slip micro-protrusions. The anti-slip micro-protrusions are interference-fitted with the outer wall of the endotracheal tube body. A circumferential lubrication and slow-release cavity is opened in the middle of the outer wall of the gradient transition support sleeve. The circumferential lubrication and slow-release cavity is embedded with a medical hydrophilic lubricating cotton pad or a pre-coated and cured hydrophilic coating.

[0007] As a further aspect of the present invention: the annular groove is coated with a medical silicone adhesive layer, wherein the medical silicone adhesive layer is a room temperature vulcanizing silicone rubber layer or a UV-cured silicone layer.

[0008] As a further embodiment of the present invention: the flexible protective end is made of medical-grade silicone or medical-grade TPE with a Shore A value of 20-30 and a wall thickness of 0.3-0.5 mm. The flexible protective end material contains 0.5%-2% by mass of medical-grade nano-silica or calcium carbonate reinforcing filler. The side vent is circular, elliptical, or oblong. The diameter deviation between the side vent and the Murphy hole is controlled within ±0.2 mm. The radius of the rounded chamfer is R0.2-0.5 mm.

[0009] As a further embodiment of the present invention: the hardness of the gradient transition support sleeve increases linearly along the axial direction from Shore A20-30 degrees at the distal end to Shore A40-50 degrees at the proximal end, the outer wall taper is 1:20-1:50, the anti-slip micro-protrusions are hemispherical, with a height of 0.1-0.2 mm, a diameter of 0.3-0.6 mm, a circumferential distribution of 12-36, an axial distribution of 2-4 rows, and an interference fit between the anti-slip micro-protrusions and the outer wall of the tracheal tube of 0.05-0.12 mm.

[0010] As a further embodiment of the present invention: the circumferential lubrication slow-release cavity is a continuous annular microgroove, multiple circumferential discontinuous grooves or spiral grooves, with a groove depth of 0.2-0.3 mm, a groove width of 2-3 mm, and a groove bottom wall thickness of not less than 0.2 mm; the medical hydrophilic lubricating cotton pad is a medical PVA sponge, polyurethane hydrophilic foam or carboxymethyl cellulose nonwoven fabric, with a saturated liquid absorption capacity of 0.1-0.5 mL.

[0011] A highly ductile hydrophilic lubricating coating is used to coat the flexible protective tip and the outer surface of the gradient transition support sleeve of an anesthesia endotracheal tube end-cap protection component against mucosal damage. The coating is characterized by comprising a base anchoring layer and a cross-linked hydrophilic top coating. The base anchoring layer is coated on the surface of the protective component substrate, and the cross-linked hydrophilic top coating covers the base anchoring layer. The two layers are bonded together through a covalent interface. The base anchoring layer is a silicone-specific base coating, comprising, by weight, 55 parts vinyl-terminated PDMS, 6 parts hydrogen-containing silicone oil, 4 parts KH560 epoxy silane, 0.15 parts platinum catalyst, and n-hexane solvent to make up to 100 parts. The cross-linked hydrophilic top coating comprises, by weight, 28 parts polyvinylpyrrolidone K90, 12 parts acrylamide-hydroxyethyl acrylate copolymer, 4 parts aziridine crosslinking agent, and 600 parts polyethylene glycol diacrylate. Add 3 parts of low molecular weight sodium hyaluronate, 1.5 parts of medical glycerin, and a mixed solvent of purified water and anhydrous ethanol in a 7:3 ratio to make up 100 parts.

[0012] As a further embodiment of the present invention: for TPE or PU substrates, the primer anchoring layer is replaced with a general-purpose primer, which, by weight, includes 65 parts of NCO-terminated polycarbonate-type polyurethane prepolymer, 3 parts of γ-aminopropyltriethoxysilane, 0.2 parts of dibutyltin dilaurate, and 100 parts of a mixed solvent of ethyl acetate and isopropanol prepared in a 1:1 ratio.

[0013] As a further embodiment of the present invention: the cross-linked hydrophilic top coating also contains 2 to 3 parts of medical-grade PEG microspheres with a particle size of 1 to 5 μm, wherein the PEG microspheres are prepared by spray drying or emulsion polymerization of polyethylene glycol with a molecular weight of 2000 to 6000.

[0014] As a further embodiment of the present invention: a gradient curing coating method for a highly ductile hydrophilic lubricating coating, used for coating the flexible protective end and the outer surface of the gradient transition support sleeve of an anesthesia endotracheal tube end anti-mucosal damage protective component, characterized by comprising the following steps: substrate pretreatment, cleaning and activating the outer surface of the flexible protective end and the gradient transition support sleeve; primer coating and semi-curing, impregnating and lifting the primer anchoring layer, pre-curing to a semi-cured state, retaining not less than 40% of active groups, with a primer dry film thickness of 2-5 μm; top coating, impregnating and lifting the crosslinked hydrophilic top coating layer on the primer semi-cured layer, with a top coating dry film thickness of 10-20 μm; final curing and crosslinking, heating to 80°C at a heating rate of 2°C / min, holding for curing for 30 min, so that the primer anchoring layer and the crosslinked hydrophilic top coating layer form covalent bonds; post-treatment, soaking in purified water for 24 h and then drying.

[0015] As a further embodiment of the present invention: the substrate pretreatment is oxygen plasma treatment with a power of 80-120W, a pressure of 10-20Pa, and a time of 30-60s, or isopropanol ultrasonic cleaning for 5-10min. After plasma treatment, the surface water contact angle is reduced to below 30°. In the primer coating and semi-curing process, the immersion time is 10-15s, the lifting speed is 5-10mm / s, and after standing at room temperature for 5min, it is pre-cured at 60℃ for 10min to reach the semi-cured state. In the top coating process, the immersion time is 8-12s, and the lifting speed is 3-8mm / s. In the post-treatment process, the substrate is soaked in purified water at 25-30℃ for 24h, with the water changed every 8h, and then vacuum dried at 60℃.

[0016] Compared with the prior art, the beneficial effects of the present invention are:

[0017] 1. This invention utilizes an integrated structural design of "flexible tip + gradual transition + drug sustained release + multiple fixation" to cover the entire operation cycle of intubation, indwelling, and extubation: The rounded, bullet-shaped flexible protective tip is wrapped with soft silicone of Shore A25 degree, replacing the original sharp hard edge, dispersing contact pressure, and avoiding puncture or scratching of the vocal cords and airway mucosa during intubation; the smooth conical transition support sleeve with gradually changing hardness completely eliminates the diameter step between the catheter tip and the tube body, solving the pain points of scratching and jamming at the glottis of traditional catheters and tissue contusion; the circumferential lubrication and sustained release cavity can hold lidocaine gel, mucosal repair gel, and other drugs, which are slowly released through contact compression, simultaneously achieving drag reduction, lubrication, and local drug efficacy; the triple fixation structure of annular groove bonding + anti-slip micro-protrusions on the inner wall ensures the anti-slip performance of the component, while the total outer diameter of the component is consistent with the catheter, without adding a diameter step and without affecting ventilation and suction functions.

[0018] 2. This invention differs from conventional single PVP lubricating coatings. The dual-layer structure of the base coating anchoring + cross-linked hydrophilic top coating achieves comprehensive performance improvement: the wet dynamic friction coefficient is as low as 0.058, far lower than the clinical standard catheter level of >0.15, significantly reducing friction and wear during insertion and placement; the coating elongation at break reaches 450%, allowing it to bend and compress synchronously with the silicone / TPE substrate, showing no cracking or peeling after 500 cycles of 30% deformation, and achieving grade 0 adhesion in the cross-cut adhesion test; the 7-day dissolution weight loss rate is only 1.8%, with grade 0 cytotoxicity, no sensitization, and a hemolysis rate of 0.3%, fully meeting the ISO10993 series of medical standards; it can also be upgraded through PEG microspheres, zwitterionic polymers, and other solutions to adapt to specific clinical needs such as long-term placement and anti-protein adsorption.

[0019] 3. This invention employs a gradient heating + semi-curing primer coating process, which avoids coating cracking and delamination caused by rapid solvent evaporation and curing stress concentration. It also ensures interlayer covalent bonding by retaining active groups, guaranteeing the interfacial bonding strength and long-term stability of the coating from a process perspective. The structural protection, surface coating lubrication, and sustained drug release in the cavity create a synergistic effect. Compared to a single structural protection solution, the histological damage score after 72 hours of placement can be further reduced by 22%, resulting in a cumulative improvement in protective effect. The solution has strong compatibility: it can be installed as an independent component in existing standard endotracheal tubes or manufactured integrally with the tube. The coating and process system are not only compatible with silicone substrates but can also be adjusted for TPE and other materials, and can be extended to guidewires, suction catheters, laryngeal masks, and other medical devices requiring lubrication and protection. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a protective component for preventing mucosal damage at the tip of an anesthetic endotracheal tube.

[0021] Figure 2 This is an enlarged view of component A in a protective assembly for preventing mucosal damage at the tip of an anesthetic endotracheal tube.

[0022] Figure 3 A flowchart illustrating the steps involved in creating a protective component to prevent mucosal damage at the tip of an anesthetic endotracheal tube.

[0023] In the figure: 1. Flexible protective end; 2. Gradient transition support sleeve; 3. Circumferential lubrication and slow-release cavity; 4. Tracheal tube body; 5. Murphy hole; 6. Annular groove; 7. Protective component substrate; 8. Primer anchoring layer; 9. Cross-linked hydrophilic top coating; 10. Covalent bonding interface. Detailed Implementation

[0024] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0025] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0026] It should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation in the specification, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0027] Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0028] In this invention, unless otherwise specified, all raw materials used are medical grade. The distal end refers to the end furthest from the operator and closest to the patient's airway, while the proximal end refers to the end closest to the operator. The biocompatibility of all parts in contact with the human body should meet the requirements of the ISO 10993 series standards. Performance testing methods are as follows: wet dynamic friction coefficient is tested according to ASTM D1894 in physiological saline at 37°C; elongation at break of the coating is tested according to ISO 527 using a dumbbell-shaped specimen at a tensile rate of 50 mm / min; adhesion is tested according to the ISO 2409 cross-cut test; loss on dissolution is tested by soaking in physiological saline at 37°C for 7 days, followed by drying and weighing; cytotoxicity is tested according to ISO 10993-5; sensitization is tested according to ISO 10993-10; hemolysis rate is tested according to ISO 10993-4; deformation tolerance test involves repeatedly bending and compressing the specimen to 30% deformation rate, then resetting it, repeating this cycle 500 times, and observing the coating condition.

[0029] Example 1: Structure and Assembly of Protective Components

[0030] like Figure 1 As shown, this embodiment provides a protective component for mucosal damage at the end of anesthesia endotracheal tube, which is fitted onto the insertion end of the endotracheal tube body 4. It includes a flexible protective end 1 and a gradient transition support sleeve 2 connected sequentially along the axial direction of the tube, as well as a circumferential lubrication and slow-release cavity 3 opened in the middle of the outer wall of the gradient transition support sleeve 2. A reference surface for coating with a lubricating coating is reserved on the outer surface of the component.

[0031] The flexible protective tip 1 is generally rounded and blunt, with a smooth spherical dome at the distal end, completely wrapping the outer wall of the catheter tip. The flexible protective tip 1 is made of Shore A25 medical-grade silicone, with a distal spherical radius of 3.5 mm, approximately 0.75 times the outer radius of the ID 7.0 catheter, and a wall thickness of 0.4 mm. After wrapping, the total outer diameter is consistent with the outer diameter of the endotracheal tube body 4, without forming a new diameter step. 1.0% by mass of medical-grade nano-silica is added to the silicone material of the flexible protective tip 1 as a reinforcing filler to improve tear resistance without significantly increasing hardness. An annular groove 6 is provided on the inner wall of the flexible protective tip 1. The annular groove 6 is 0.3 mm wide and 0.2 mm deep, and it is interference-fitted with the pre-set annular flange at the tip of the endotracheal tube body 4 with an interference amount of 0.1 mm. The annular groove 6 is coated with a room temperature vulcanizing medical silicone adhesive layer or a UV-cured silicone layer, with a shear strength of not less than 0.5 MPa after curing, forming a dual fixation of locking and bonding. A side ventilation hole with a diameter of 2.0 mm is opened on the side wall corresponding to the Murphy orifice 5 of the endotracheal tube body 4, aligned with the Murphy orifice 5, with a diameter deviation controlled within ±0.2 mm. A 0.3 mm rounded chamfer is provided around the edge of the side ventilation hole to avoid sharp edges damaging the mucosa, while ensuring that ventilation and suction functions are not interfered with. The side ventilation hole is circular, consistent with the shape of the Murphy orifice 5; in other embodiments, it can also be elliptical or oblong. Positioning marks or scale lines can be provided on the outer wall of the component to facilitate alignment during assembly.

[0032] The gradient transition support sleeve 2 is integrally molded at the proximal end of the flexible protective end 1, extending 6mm along the axial direction of the catheter. Its outer wall has a smooth conical surface with a taper of 1:30, thus eliminating the diameter step between the rigid end of the catheter and the tube body. The gradient transition support sleeve 2 is made of medical-grade silicone, with its hardness linearly increasing from Shore A25 at the distal end to Shore A45 at the proximal end along the axial direction, achieved through a segmented molding process. The inner wall of the gradient transition support sleeve 2 is provided with circumferentially evenly distributed hemispherical anti-slip micro-protrusions. The protrusions are 0.15mm high and 0.4mm in diameter, with 24 protrusions distributed circumferentially and 3 rows distributed axially. The anti-slip micro-protrusions are interference-fitted with the outer wall of the endotracheal tube body 4, with an interference amount of 0.1mm, further improving the component's anti-slip performance.

[0033] The circumferential lubrication and slow-release cavity 3 is a continuous annular microgroove structure located in the middle of the outer wall of the gradually transitioning support sleeve 2. The groove is 0.25 mm deep, 2.5 mm wide, and the bottom wall thickness is not less than 0.2 mm. A medical PVA hydrophilic lubricating cotton pad is embedded in the circumferential lubrication and slow-release cavity 3, with a saturated absorbency of 0.3 mL. Before clinical use, it is soaked in lidocaine gel. In other embodiments, the circumferential lubrication and slow-release cavity 3 may also be multiple circumferential discontinuous grooves or spiral grooves; the cotton pad may also be medical polyurethane hydrophilic foam or carboxymethyl cellulose nonwoven fabric, with a saturated absorbency of 0.1–0.5 mL. Before clinical use, it may be soaked in paraffin oil, lidocaine gel, mucosal repair gel, or chlorhexidine antibacterial gel, etc.

[0034] The assembly relationship in this embodiment is as follows: the flexible protective end 1 is inserted into the distal end of the endotracheal tube body 4, so that the annular groove 6 is press-fitted with the pre-set annular flange at the tip of the endotracheal tube body 4, and the side ventilation hole is aligned with the Murphy hole 5; after the room temperature vulcanizing medical silicone adhesive or UV-curing silicone is cured in the annular groove 6, the flexible protective end 1 and the endotracheal tube body 4 are fixed by both pressing and bonding; the anti-slip micro-protrusions on the inner wall of the gradient transition support sleeve 2 are press-fitted with the outer wall of the endotracheal tube body 4, providing a third layer of anti-slip fixation. For existing standard catheters without a pre-set flange, a medical-grade fixing ring can be first fitted onto the outer wall of the catheter to form an annular flange. The fixing ring can be fixed by heat shrinking, bonding or ultrasonic welding.

[0035] The protective logic in this embodiment during the three-stage clinical procedure is as follows: During intubation, the rounded, bullet-shaped flexible protective tip 1 acts as a guide contact with the airway tissue, dispersing the pressure of the tip with its soft contact surface to avoid sharp edge punctures; the smooth conical surface of the gradient transition support sleeve 2 eliminates the diameter step between the rigid end of the catheter and the tube body, reducing the risk of scraping and jamming at the glottis; lidocaine gel infiltrated in the circumferential lubrication slow-release cavity 3 is slowly released through contact compression, reducing pushing resistance and exerting a local anesthetic effect. During indwelling, the flexible protective tip 1 and the gradient transition support sleeve 2 completely isolate the rigid edge of the catheter from the tracheal mucosa; the side ventilation port maintains normal ventilation and secretion drainage. During extubation, the soft tip and lubrication structure reduce secondary frictional damage during extubation.

[0036] In this embodiment, the total outer diameter of the component is consistent with the outer diameter of the catheter tube, with no step; there is no jamming during the intubation test, and it passes through the glottis smoothly; after extubation, laryngoscope observation shows no obvious damage to the vocal cords; in a 37°C artificial airway model, with a continuous axial tensile force of 10N for 1 minute, the component does not shift.

[0037] Example 2: Preparation and Properties of High-Expansion Hydrophilic Lubricating Coatings

[0038] like Figure 2As shown, this embodiment provides a highly ductile hydrophilic lubricating coating for protective components, comprising a two-layer structure system consisting of a primer anchoring layer 8 and a cross-linked hydrophilic topcoat 9. The primer anchoring layer 8 is coated on the surface of the protective component substrate 7, and the cross-linked hydrophilic topcoat 9 covers the primer anchoring layer 8. The two layers are bonded together through a covalent bonding interface 10. In this embodiment, the protective component substrate 7 is a medical-grade silicone substrate, and a silicone-specific primer formulation is used accordingly.

[0039] The primer preparation method is as follows: Take 55 parts by weight of vinyl-terminated PDMS, 6 parts by weight of hydrogen-containing silicone oil, 4 parts by weight of KH560 epoxy silane, and 0.15 parts by weight of platinum catalyst. Add n-hexane to bring the total to 100 parts, stir to disperse evenly, and then filter to remove bubbles. The vinyl-terminated PDMS has a vinyl content of 0.15 mmol / g, is homogeneous with the silicone substrate, and can form chemical bonds; the hydrogen-containing silicone oil has a hydrogen content of 0.8 mmol / g, serving as a hydrosilylation crosslinking agent; KH560 provides epoxy groups to react with the topcoat; and the platinum catalyst concentration is 3000 ppm, catalyzing the hydrosilylation reaction.

[0040] The preparation method of the topcoat is as follows: by weight, 28 parts of polyvinylpyrrolidone (PVP) K90, 12 parts of acrylamide-hydroxyethyl acrylate copolymer (P(AM-HEA)), 4 parts of aziridine crosslinking agent (CX-100), 3 parts of polyethylene glycol diacrylate (PEGDA600), 1.5 parts of low molecular weight sodium hyaluronate, and 1.5 parts of medical glycerin are added to a mixed solvent of purified water and anhydrous ethanol in a ratio of 7:3 to make up to 100 parts. The mixture is stirred at 40°C to dissolve into a uniform and transparent solution and then cooled to room temperature. Among them, PVP K90 is pharmacopoeia grade with a molecular weight of 900,000 to 1,200,000 and serves as a hydrophilic lubricating substrate; P(AM-HEA) has a hydroxyl value of 2.0 mmol / g, contains active hydroxyl groups, and can undergo covalent reactions with residual epoxy groups in the primer and aziridine crosslinking agents; CX-100 can covalently react with copolymer hydroxyl groups and residual active groups in the primer to construct a three-dimensional network; PEGDA 600 is a flexible crosslinking agent that can improve the elongation at break of the coating; low molecular weight sodium hyaluronate has a molecular weight of 100,000 to 200,000 Da and serves as an endogenous lubricating component; and medical-grade glycerin is used as a plasticizer to improve the dry-state flexibility of the coating.

[0041] In this embodiment, the base anchoring layer 8 and the cross-linked hydrophilic top coating layer 9 are sequentially coated onto the surface of the silicone protective component substrate 7 using the gradient curing coating method described in Example 3, forming a double-layer covalently bonded coating. The silicone-specific base coating forms homogeneous chemical bonds with the silicone substrate, which can improve adhesion to level 0 and maintain the elasticity of the substrate; the hydrophilic components in the cross-linked hydrophilic top coating layer 9 are anchored in the three-dimensional network through covalent bonds, reducing the dissolution rate, while the PEGDA 600 flexible cross-linking agent allows the coating to bend and deform synchronously with the protective component.

[0042] The performance test results of the coating obtained in this embodiment are as follows: the wet dynamic friction coefficient is 0.058; the elongation at break of the coating is 450%; the coating remains intact after 500 bending and extrusion cycles, without cracking or peeling; the 7-day dissolution weight loss rate is 1.8%; the cytotoxicity is grade 0 according to ISO 10993-5; the sensitization is non-sensitizing; the hemolysis rate is 0.3%; after sterilization with ethylene oxide, the wet dynamic friction coefficient is 0.061, the elongation at break is 435%, and the performance shows no significant degradation.

[0043] As an optional optimization and upgrade, this embodiment can also add 2-3 parts of medical-grade PEG microspheres with a particle size of 1-5 μm to the crosslinked hydrophilic top coating 9. The PEG microspheres are prepared by spray drying or emulsion polymerization of polyethylene glycol with a molecular weight of 2000-6000. They slowly swell and release polyethylene glycol in body fluids, continuously replenishing lubricating components and improving long-term lubrication stability by 40%. Another optional solution is to replace 30% by mass of polyvinylpyrrolidone in the top coating with sulfobetaine methacrylate polymer PSBMA. The molecular weight of PSBMA is preferably 50,000-200,000, and the content of sulfobetaine monomer is not less than 80%. It utilizes the zwitterionic structure to resist protein adsorption and is suitable for long-term indwelling scenarios in intensive care. In addition, PVP K90 can be partially replaced by PVP K30 or PVP K60 to adjust the solution viscosity and coating hydration rate; the hydroxyl value of P(AM-HEA) can be adjusted in the range of 1.5 to 2.5 mmol / g; the aziridine crosslinking agent CX-100 can be replaced by other multifunctional aziridine crosslinking agents or carbodiimide crosslinking agents, which must meet medical grade requirements.

[0044] Example 3: Implementation of Gradient Curing Coating Process

[0045] This embodiment provides a gradient curing coating method for a lubricating coating on a protective component, the process flow of which is as follows: Figure 3 As shown. In this embodiment, a silicone protective component is used as the substrate, coated with the primer anchoring layer 8 and the cross-linked hydrophilic top coating layer 9 described in Embodiment 2.

[0046] Step 1 is substrate pretreatment. The outer surface of the silicone protective component is treated with oxygen plasma at a power of 100W, a pressure of 15Pa, and a treatment time of 60s. This introduces active groups such as hydroxyl and carboxyl groups onto the substrate surface, increasing surface energy. Before treatment, the surface is ultrasonically cleaned with isopropanol for 8 minutes to remove surface release agent and oil, and then dried. After plasma treatment, the water contact angle on the substrate surface decreases to below 30°, which is beneficial for primer wetting and chemical bonding. For silicone substrates, a pretreatment step with a primer-specific silane treatment solution can be added to further improve adhesion.

[0047] Step 2 involves primer coating and semi-curing. The primer anchoring layer 8 is coated using an dip-coat method, with an immersion time of 10 seconds and a lifting speed of 6 mm / s. After coating, it is allowed to stand at room temperature for 5 minutes to allow solvent evaporation, and then pre-cured at 60°C for 10 minutes to reach a semi-cured state. The semi-cured state must retain at least 40% of the active epoxy groups to facilitate subsequent reaction with the hydroxyl and other active groups in the cross-linked hydrophilic topcoat 9 to form covalent bonds. In this embodiment, the degree of semi-curing is controlled by monitoring the change in the area of ​​the epoxy characteristic peaks using infrared spectroscopy; the measured epoxy group retention rate is approximately 58%. The dry film thickness of the primer anchoring layer 8 is controlled at 3–4 μm; too thin a layer results in insufficient anchoring, while too thick a layer increases rigidity and interfacial stress.

[0048] Step 3 is the topcoat application. The cross-linked hydrophilic topcoat 9 is applied to the semi-cured primer layer using a dip-coating method, with an immersion time of 10 seconds and a lifting speed of 5 mm / s. The dry film thickness of the cross-linked hydrophilic topcoat 9 is controlled at 15 μm; too thin and lubrication will be insufficient, too thick and cracking will be likely.

[0049] Step 4 is the final curing and crosslinking. The temperature is increased to 80℃ at a rate of 2℃ / min and held for 30 minutes. Gradual heating avoids rapid solvent evaporation and stress concentration during curing. During curing, the interfacial covalent bonding between the primer anchoring layer 8 and the crosslinked hydrophilic top coating 9 is completed simultaneously, as well as the construction of the three-dimensional network of the crosslinked hydrophilic top coating 9 itself. After curing, the temperature is allowed to cool naturally to room temperature to avoid thermal stress caused by sudden cooling.

[0050] Step 5 is the post-treatment. The coated protective components are immersed in purified water at 25°C for 24 hours, with the water changed every 8 hours to wash away free components and unreacted small molecules; then they are vacuum dried at 60°C and sterilized with ethylene oxide. Post-treatment can effectively reduce the coating dissolution rate and improve biosafety.

[0051] As an optional process optimization, the top coating can be applied in two or three dip coatings, with each coating dried at 60°C for 5 minutes before the next dip coating, to improve thickness uniformity and surface smoothness. For protective ends with complex curved structures, low-speed rotary dip coating or rotary sling coating can be used to reduce sagging and edge buildup. Online thickness measuring instruments and infrared spectrometers can be used to monitor coating thickness and curing degree. The coating environment temperature should be controlled at 20-25°C and the relative humidity at 40%-60%.

[0052] The results of this embodiment are as follows: the cross-cut adhesion is grade 0 with no delamination; the component shows no cracking after 500 bending and extrusion cycles; the coating thickness deviation does not exceed ±1.5μm; and the dissolution weight loss rate is 1.8%.

[0053] Example 4: Coating and Coating Implementation of TPE Substrate Protective Components

[0054] The difference between this embodiment and Embodiments 2 and 3 is that the protective component substrate 7 is made of medical-grade TPE material, and the primer anchoring layer 8 uses a general-purpose primer formulation. The preparation method of the general-purpose primer is as follows: Take 65 parts by weight of NCO-terminated polycarbonate-type polyurethane prepolymer solution, 3 parts of γ-aminopropyltriethoxysilane KH550, and 0.2 parts of dibutyltin dilaurate DBTDL. Add a mixed solvent of ethyl acetate and isopropanol in a 1:1 ratio to bring the total to 100 parts. Stir and disperse evenly, then filter to remove bubbles. The NCO-terminated polycarbonate-type polyurethane prepolymer has a solid content of 30% and a molecular weight of 8000, serving as the main film-forming component. The NCO groups can react with hydroxyl or amino groups on the substrate surface and crosslink with the active groups of the topcoat layer. KH550 is a medical-grade coupling agent that enhances interfacial bonding and participates in the construction of the crosslinking network. DBTDL is a medical-grade catalyst that catalyzes the crosslinking reaction at low temperatures, reducing the curing temperature. The mixed solvent is used to adjust the coating viscosity, ensuring fast drying and low swelling to prevent substrate deformation.

[0055] Regarding the coating process, the TPE protective component was first treated with oxygen plasma for 45 seconds, and then dipped in a general-purpose primer at a dipping speed of 8 mm / s and an immersion time of 12 seconds. After coating, it was pre-cured at 60°C for 10 minutes to a semi-cured state, retaining active NCO groups. Infrared monitoring showed that the NCO retention rate was approximately 55%. The formulation and coating process of the crosslinked hydrophilic topcoat 9 were the same as in Examples 2 and 3.

[0056] The results of this embodiment are as follows: adhesion grade 0; wet dynamic friction coefficient 0.062; elongation at break 420%; coating intact after 500 bending and extrusion cycles, with no cracks or peeling; 7-day dissolution weight loss rate 2.1%.

[0057] Example 5: Joint Implementation and Synergistic Effects of the Entire System

[0058] This embodiment is a joint implementation of the entire system. The outer surface of the protective component described in Embodiment 1 is coated with the silicone-specific primer and cross-linked hydrophilic top coating described in Embodiment 2. The cross-linked hydrophilic top coating adopts an upgraded scheme containing PEG microspheres. The coating is coated and cured according to the gradient curing coating method described in Embodiment 3. Lidocaine gel is impregnated in the circumferential lubrication and slow-release cavity 3.

[0059] In this embodiment, the wet dynamic friction coefficient of the cannulation simulation display component surface was 0.052; after 72 hours of indwelling, the histological damage score was reduced by 22% compared with the single structural protection group, proving that there is a synergistic effect among structural protection, surface coating lubrication, and cavity drug sustained release.

[0060] In comparison, Comparative Example 1 used a common silicone soft tip, which caused significant jamming at the step during insertion, posing a high risk of component slippage. Comparative Example 2 used a conventional single PVP coating, with an initial wet dynamic friction coefficient of 0.12. After 500 bending and extrusion cycles, flaking occurred and the friction coefficient increased to 0.24. The 7-day dissolution weight loss rate was 9.1%, the cross-cut adhesion was grade 2, and the elongation at break was 175%. Comparative Example 3 used the same double-layer coating as this invention but was cured at 80℃ in a single step without retaining the active groups in the primer or using a gradient heating method. The result was 32% cracking and delamination, a 7-day dissolution weight loss rate of 3.6%, a cross-cut adhesion of grade 1, and an elongation at break of 255%. The solution of this invention showed no jamming during insertion, no risk of component slippage, a wet dynamic friction coefficient of 0.058, an intact coating with 92% lubrication retention after 500 bending and extrusion cycles, a 7-day dissolution weight loss rate of 1.8%, an adhesion grade of 0, and an elongation at break of 450%.

[0061] In another embodiment, the aforementioned protective component can be manufactured as a standalone kit or integrally molded with the endotracheal tube. The coating and coating method described above are not only applicable to endotracheal tube protective components, but can also be extended to the surfaces of medical devices requiring lubrication and flexibility, such as guidewires, suction catheters, and laryngeal masks.

[0062] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A protective assembly for preventing mucosal damage at the tip of an anesthetic endotracheal tube, comprising a flexible protective end (1) and a gradually transitioning support sleeve (2) connected axially to the proximal end of the flexible protective end (1), the protective assembly being fitted onto the insertion end of the endotracheal tube body (4), characterized in that, The flexible protective end (1) is rounded and blunt, with a smooth spherical arc at the distal end that completely wraps around the outer wall of the tip of the endotracheal tube body (4). After wrapping, the total outer diameter is consistent with the outer diameter of the endotracheal tube body (4). The inner wall of the flexible protective end (1) is provided with an annular groove (6) that is interference-fitted with the pre-set annular flange at the tip of the endotracheal tube body (4). The side wall is provided with a side ventilation hole that is aligned with the Murphy hole (5) of the endotracheal tube body (4). The edge is provided with rounded chamfers. The material hardness of the gradual transition support sleeve (2) gradually increases from the far end to the near end along the axial direction. The outer wall is a smooth conical surface. The inner wall is provided with circumferentially distributed anti-slip micro-protrusions. The anti-slip micro-protrusions are interference fit with the outer wall of the tracheal tube body (4). A circumferential lubrication slow-release cavity (3) is opened in the middle of the outer wall of the gradual transition support sleeve (2). The circumferential lubrication slow-release cavity (3) is embedded with a medical hydrophilic lubricating cotton pad or a pre-coated cured hydrophilic coating.

2. The protective assembly for preventing mucosal damage at the tip of an anesthetic endotracheal tube according to claim 1, characterized in that, The annular groove (6) is coated with a medical silicone adhesive layer, which is a room temperature vulcanizing silicone rubber layer or a UV-cured silicone layer.

3. The protective assembly for preventing mucosal damage at the tip of an anesthetic endotracheal tube according to claim 1, characterized in that, The flexible protective end (1) is made of medical silicone or medical TPE with a Shore A of 20 to 30 degrees and a wall thickness of 0.3 to 0.5 mm. The flexible protective end (1) is made of 0.5% to 2% medical-grade nano-silica or calcium carbonate reinforcing filler. The side vent is circular, elliptical or oblong. The diameter deviation between the side vent and the Murphy hole (5) is controlled within ±0.2 mm. The radius of the rounded chamfer is R0.2 to 0.5 mm.

4. The protective assembly for preventing mucosal damage at the tip of an anesthetic endotracheal tube according to claim 1, characterized in that, The hardness of the gradual transition support sleeve (2) increases linearly along the axial direction from Shore A20-30 degrees at the distal end to Shore A40-50 degrees at the proximal end. The outer wall taper is 1:20-1:

50. The anti-slip micro-protrusions are hemispherical with a height of 0.1-0.2 mm and a diameter of 0.3-0.6 mm. The number of circumferentially distributed protrusions is 12-36, and the number of axially distributed protrusions is 2-4. The interference fit between the anti-slip micro-protrusions and the outer wall of the tracheal tube body (4) is 0.05-0.12 mm.

5. The protective assembly for preventing mucosal damage at the tip of an anesthetic endotracheal tube according to claim 1, characterized in that, The circumferential lubrication and slow-release cavity (3) is a continuous annular microgroove, multiple circumferential discontinuous grooves or spiral grooves, with a groove depth of 0.2-0.3 mm, a groove width of 2-3 mm, and a wall thickness of not less than 0.2 mm at the bottom of the groove. The medical hydrophilic lubricating cotton pad is a medical PVA sponge, polyurethane hydrophilic foam or carboxymethyl cellulose nonwoven fabric, with a saturated liquid absorption capacity of 0.1-0.5 mL.

6. A highly ductile hydrophilic lubricating coating for coating the outer surface of the flexible protective end (1) and the gradient transition support sleeve (2) of an anesthesia endotracheal tube end-capsule anti-mucosal damage protective assembly, characterized in that, The product includes a base anchoring layer (8) and a cross-linked hydrophilic top coating layer (9). The base anchoring layer (8) is coated on the surface of the protective component substrate (7). The cross-linked hydrophilic top coating layer (9) covers the base anchoring layer (8). The two layers are bonded together through a covalent bonding interface (10). The base anchoring layer (8) is a silicone-specific base coating, which by mass includes 55 parts of vinyl-terminated PDMS, 6 parts of hydrogen-containing silicone oil, 4 parts of KH560 epoxy silane, 0.15 parts of platinum catalyst, and n-hexane solvent to make up 100 parts. The cross-linked hydrophilic top coating layer (9) by mass includes 28 parts of polyvinylpyrrolidone K90, 12 parts of acrylamide-hydroxyethyl acrylate copolymer, 4 parts of aziridine crosslinking agent, 3 parts of polyethylene glycol diacrylate 600, 1.5 parts of low molecular weight sodium hyaluronate, 1.5 parts of medical glycerin, and a mixed solvent of purified water and anhydrous ethanol in a ratio of 7:3 to make up 100 parts.

7. The high-ductility hydrophilic lubricating coating according to claim 6, characterized in that, For TPE or PU substrates, the primer anchoring layer (8) is replaced with a general-purpose primer, which by mass includes 65 parts of NCO-terminated polycarbonate polyurethane prepolymer, 3 parts of γ-aminopropyltriethoxysilane, 0.2 parts of dibutyltin dilaurate, and 100 parts of a mixed solvent of ethyl acetate and isopropanol prepared in a 1:1 ratio.

8. The high-ductility hydrophilic lubricating coating according to claim 6, characterized in that, The cross-linked hydrophilic top coating (9) also contains 2 to 3 parts of medical-grade PEG microspheres with a particle size of 1 to 5 μm, which are prepared by spray drying or emulsion polymerization of polyethylene glycol with a molecular weight of 2000 to 6000.

9. A gradient curing coating method for a highly ductile hydrophilic lubricating coating, used to coat the outer surface of a flexible protective end (1) and a gradient transition support sleeve (2) of an anesthesia endotracheal tube end anti-mucosal damage protective component, characterized in that, Includes the following steps: Substrate pretreatment: Cleaning and activation treatment of the outer surfaces of the flexible protective end (1) and the gradient transition support sleeve (2); base coating and semi-curing: impregnation and lifting of the base coating anchoring layer (8), pre-curing to semi-cured state, retaining no less than 40% of active groups, and the dry film thickness of the base coating is 2-5 μm. Top coating: Impregnate the semi-cured base coat with a cross-linked hydrophilic top coating (9), and the dry film thickness of the top coating is 10-20 μm. Final curing and crosslinking: the temperature is increased to 80℃ at a rate of 2℃ / min and kept at the temperature for 30min to form a covalent bond between the base coating anchor layer (8) and the crosslinked hydrophilic top coating layer (9); post-treatment: soak in purified water for 24h and then dry.

10. The gradient curing coating method for the high-ductility hydrophilic lubricating coating according to claim 9, characterized in that, The substrate pretreatment is oxygen plasma treatment with a power of 80-120W, a pressure of 10-20Pa, and a time of 30-60s, or isopropanol ultrasonic cleaning for 5-10min. After plasma treatment, the surface water contact angle is reduced to below 30°. In the primer coating and semi-curing process, the immersion time is 10-15s, the lifting speed is 5-10mm / s, and after standing at room temperature for 5min, it is pre-cured at 60℃ for 10min to reach the semi-cured state. In the top coating process, the immersion time is 8-12s, and the lifting speed is 3-8mm / s. In the post-treatment process, the substrate is soaked in purified water at 25-30℃ for 24h, with the water changed every 8h, and then vacuum dried at 60℃.

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