Circulating fluid and lubricity modifier

Abstract

To provide a circulating liquid which, even when an aqueous circulating liquid is applied to a blood vessel model, realizes a lubricating property capable of withstanding a pressing force equivalent to that applied when a catheter is inserted into an actual human blood vessel.SOLUTION: The circulating liquid is used for a catheter simulator having a blood vessel model, and contains a mixture of a second water-soluble polymer having a hydrophilic group and a third polymer having a hydrophobic group, or a mixture of a first water-soluble polymer having both a hydrophilic group and a hydrophobic group and the third polymer.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention is suitable for use in circulating fluids for catheter simulators that use blood vessel models made of silicone rubber, urethane rubber, etc. The lubricity modifier of the present invention also improves the lubricity between crosslinkable polymer materials. [Background technology]

[0002] The present inventor has developed and marketed a catheter simulator that mimics the human body (see Patent Document 1). In this catheter simulator, a partition member is built into a mannequin body made of a transparent material, a three-dimensional blood vessel model is supported on one side of the partition member, and an auxiliary device for operating the blood vessel model is placed thereon. The blood vessel model is made of silicone rubber, and the auxiliary device includes a tank, a pump, and a connecting pipe. The tank contains a circulating fluid, which is circulated through the blood vessel model via the connecting pipe by the pump. When a catheter is inserted into this blood vessel model, the lubricity between the surface of the silicone rubber and the surface of the catheter becomes an issue. Also, please refer to Patent Document 2, which discloses a technique related to the present invention. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-267565 [Patent Document 2] Patent No. 5992031 Summary of the Invention [Problem to be solved by the invention]

[0004] According to the catheter simulator disclosed in Patent Document 1, a catheter can be inserted into a blood vessel model made of silicone rubber while a circulating fluid is circulating through the blood vessel model. The circulating fluids used are either silicone oil-based (oil-based circulating fluids) or water-based (aqueous-based circulating fluids), but aqueous circulating fluids are preferred due to their similarity to blood. If water is simply circulated through the blood vessel model, the contact resistance of the catheter with the inner wall of the blood vessel model will increase, making it difficult to insert the catheter smoothly. Therefore, a surfactant is mixed into the water as a lubricity adjuster, which reduces the frictional resistance between the catheter and the inner surface of the blood vessel model, allowing the catheter to be inserted smoothly into the blood vessel model.

[0005] However, even if a circulating fluid made of water mixed with a surfactant is circulated through a vascular model, it does not reproduce the blood vessels through which actual blood circulates. Therefore, in simulations using such a circulating fluid, the feeling of catheter insertion was undeniably uncomfortable compared to actual surgery. For example, when the catheter passed through a tortuous section of the vascular model, the frictional resistance was significantly greater than in actual surgery. Furthermore, when the inserted catheter was left stationary for a few seconds, the static friction coefficient between the catheter and the vascular model became abnormally large, making it difficult to push or pull out the inserted catheter (hereinafter, these phenomena are referred to as "adhesion").

[0006] The lubricity regulator disclosed in Patent Document 2 was developed to solve this problem, and by using a surfactant and a water-soluble metal salt in combination as a lubricity regulator, the feeling of inserting a catheter into a blood vessel model can be made to resemble the feeling of inserting a catheter during actual surgery. Use of the lubricity regulator disclosed in Patent Document 2 can prevent adhesion between the blood vessel model and the catheter even in tortuous parts of the blood vessel model, and solves the problem of sudden increases in insertion resistance during catheter manipulation.

[0007] Even when the lubricity regulator disclosed in Patent Document 2 was used, adhesions sometimes occurred when the force with which the catheter was pressed against the blood vessel wall (hereinafter referred to as "pressing force") reached 5 N (approximately 0.5 kg) or more. Similar adhesions also occur in human blood vessels when the pressing force increases. However, evaluations by the inventors confirmed that adhesions occur even when the lubricity regulator was used, even with a smaller pressing force than in human blood vessels. In an attempt to prevent adhesions, attempts were made to increase the amount of surfactant or water-soluble ionic compound mixed in, but the effect was saturated even with increased amounts, and it was not possible to reproduce characteristics equivalent to those of human blood vessels. Furthermore, increasing the amount of surfactant mixed in is undesirable because it causes the circulating fluid to feel slimy.

[0008] Using silicone oil as a circulating fluid was effective in preventing adhesions, but so-called oil-based silicone oils (including those dispersed in water using emulsifiers, etc.) and water-soluble silicone oils such as polyether-modified silicones have physical properties that are so different from those of blood that they do not provide a realistic feel when handling the catheter when inserting it. [Means for solving the problem]

[0009] The inventors have conducted extensive research to achieve lubrication properties that can withstand the same pressing force as when inserting a catheter into an actual human blood vessel, even when a so-called aqueous circulating fluid is applied to the blood vessel model. As a result, they discovered that the use of a specific water-soluble polymer significantly improves the adhesion resistance of the catheter to the blood vessel model, making it closer to the characteristics of the actual human blood vessel during surgery. As a result, even in areas where large pressing forces are likely to occur during surgery, such as the common iliac artery, aorta, and common carotid artery, the catheter did not adhere to the inner surface of the blood vessel model, and it was possible to pass the catheter with the same operating feel as during actual surgery.

[0010] That is, the first aspect of the present invention is defined as follows. A circulating fluid used in a catheter simulator, the circulating fluid containing a water-soluble polymer, the water-soluble polymer containing a water-soluble polymer having both a hydrophilic group and a hydrophobic group, and / or a mixture of a polymer having a hydrophilic group and a polymer having a hydrophobic group.

[0011] According to the circulating fluid of the first aspect defined above, in the case of a water-soluble polymer having both hydrophilic and hydrophobic groups, the hydrophobic group (lipophilic group) of the water-soluble polymer is bound to the inner circumferential surface of the blood vessel model, exposing the hydrophilic group. The hydrophilic group is bound to the hydrophilic group, exposing the hydrophobic group. The hydrophobic group of the water-soluble polymer is bound to the hydrophilic group, exposing the hydrophobic group. In this way, multiple layers of water-soluble polymer are formed on the inner circumferential surface of the blood vessel model. Although the bonding strength between each layer of the water-soluble polymer is weak, the complex entanglement of polymer chains of a certain length forms a strong lubricating layer that is difficult to separate from the inner circumferential surface. Therefore, the inner circumferential surface of the blood vessel model possesses physical properties similar to those of endothelial cells present inside human blood vessels, and lubricity can be maintained without adhesion even when a large pressure is applied to the catheter. As a result, the catheter was able to pass through easily and with a feeling of operation (friction) similar to that during actual surgery, both in areas where small pressure is normally applied, such as the cerebral artery area, and in areas where large pressure is applied, such as the aorta.

[0012] While it has been possible to reproduce lubrication properties similar to those of human blood vessels by pre-hydrophilizing the inner surface of a blood vessel model using various methods, the properties of the hydrophilic layer formed in this way are prone to change due to deterioration over time, adhesion of foreign matter to the surface, wear during use, etc. According to the method of the present invention, even if the water-soluble polymer attached to the inner surface of the blood vessel model is lost due to wear, etc., the water-soluble polymer dissolved in the circulating fluid is re-adhered to the inner surface of the blood vessel model to replenish it, thereby continuously maintaining certain properties. Furthermore, after use, the water-soluble polymer is discharged and removed along with the circulating fluid and replenished with new circulating fluid at the next use, so that new water-soluble polymer is always supplied, and no fluctuations in properties occur.

[0013] As a result, in the catheter simulator equipped with the blood vessel model through which the circulating fluid of the first aspect is circulated, the feeling of inserting a catheter into the blood vessel model is close to the feeling of inserting a catheter into a blood vessel in a human body, and the multiple layers of water-soluble polymer ensure that the catheter maintains its adhesion resistance even when a large pressure force is applied to it.

[0014] Examples of water-soluble polymers having both hydrophilic and hydrophobic groups include PVA (polyvinyl alcohol) and methyl cellulose. Other examples include natural polymers such as proteins and starches, as well as synthetic polymers such as polyacrylic acid, polyacrylamide, polyethylene oxide, poly(vinylpyrrolidone), polyvinylamide, and polyamines. The molecular weight (degree of polymerization) and blending amount of these water-soluble polymers can be selected as desired depending on the diameter and area of ​​the inner circumferential surface of the blood vessel model used in the catheter simulator, the type of catheter, etc. The blending amount of the water-soluble polymer is preferably about 0.5 to 8.0% by mass relative to water.

[0015] From the viewpoints of material cost, decomposability after use, washability, etc., it is preferable to use PVA. In the case of PVA, the average molecular weight (number average) is preferably about 500 to 2000, and the degree of saponification is preferably 75 or more. In the case of PVA, it is preferable to maintain the pH in the range from weakly basic to weakly acidic in order to ensure its dispersibility and to approximate that of human blood, and for this purpose it is preferable to add a pH buffer.

[0016] Because PVA is a water-based adhesive, when the water evaporates after use of the catheter simulator, it forms a film that adheres to various substrates, causing clogging and adhesion, which may interfere with subsequent use. To prevent the formation of a film from water-soluble polymers such as PVA, it is preferable to mix sugars (sucrose, fructose, etc.) into the circulating fluid. By mixing sugars, etc., the formation of a film is suppressed when the circulating fluid containing water-soluble polymers such as PVA dries (evaporates), and the powder becomes powdery after drying, making it easy to remove even if it adheres to various substrates. The amount of sugar to be added can be selected appropriately depending on the properties of the water-soluble polymer such as PVA, but it is preferable to add 50 to 200 parts by mass of sugar to 100 parts by mass of PVA.

[0017] In the case of a mixture of a water-soluble polymer with hydrophilic groups and a water-soluble polymer with hydrophobic groups, the two polymers are thought to intertwine in the circulating fluid, forming molecules that appear to have both hydrophilic and hydrophobic groups. Similar to the previously mentioned water-soluble polymers that have both hydrophilic and hydrophobic groups alone, such as PVA and methylcellulose, these molecules overlap in multiple layers on the inner surface of the blood vessel model, forming a layer of molecules that exhibits the same lubricity and toughness as PVA and methylcellulose.

[0018] Here, the blending ratio of the water-soluble polymer having hydrophilic groups to the water-soluble polymer having hydrophobic groups is preferably 1:1, with the total amount of hydrophilic groups and the total amount of hydrophobic groups being 1:1, but is not particularly limited thereto. In order to reliably entangle a water-soluble polymer having a hydrophilic group and a polymer having a hydrophobic group, the main chain constituting the polymer must have a predetermined length.

[0019] In addition to the water and water-soluble polymers described above, it is preferable to add to the circulating fluid a lubricity adjuster introduced in Patent Document 2. The contents of Patent Document 2 are cited here for reference. As already mentioned, the water-soluble polymer having both a hydrophilic group and a hydrophobic group, and the mixture of a water-soluble polymer having a hydrophilic group and a polymer having a hydrophobic group are also lubricity adjusters. As a lubricity adjuster, it can be blended into the circulating fluid of the catheter simulator alone, together with a surfactant, or together with a surfactant and a water-soluble ionic compound.

[0020] In lubricity modifiers, the role of surfactants is primarily to reduce the coefficient of dynamic friction between objects (such as between a silicone rubber surface and a catheter surface) and to promote the bonding (multilayering) of the water-soluble polymers through interactions (ionic bonds, hydrophobic bonds, hydrogen bonds, covalent bonds, etc.) between the surfactant and the water-soluble polymers. This reduces resistance when inserting a catheter, for example, when the catheter comes into contact with the surface of a silicone rubber blood vessel model, allowing the operator to insert the catheter into the blood vessel model smoothly.

[0021] On the other hand, the role of the water-soluble ionic compound is to reduce the dynamic friction coefficient as described above, as well as to prevent adhesion between the silicone rubber and the parts that come into contact with it (i.e., reduce the static friction coefficient), and to further promote bonding (multilayering) of the water-soluble polymer through interactions (ionic bonds, hydrophobic bonds, hydrogen bonds, covalent bonds, etc.) between the water-soluble ionic compound, surfactant, and water-soluble polymer, and to increase the toughness of the formed lubricating layer.

[0022] If this layer consisting of a surfactant and a water-soluble ionic compound does not contain a water-soluble polymer, it will easily collapse when the pressure of the catheter increases, causing direct contact between the catheter and the surface of the blood vessel model, resulting in adhesion. Similar to surfactants, water-soluble polymers (same molecule) with both hydrophilic and hydrophobic groups form a lubricating layer between objects (such as between a silicone rubber surface and a catheter surface) to reduce the coefficient of kinetic friction. A circulating fluid containing a surfactant, a water-soluble ionic compound, and a water-soluble polymer forms a multilayered, lamellar structure due to interactions between the surfactant and the water-soluble ionic compound (ionic, hydrophobic, hydrogen, covalent, etc.), and the molecular chains of the water-soluble polymer become intricately entangled over a wide area, forming a tough lubricating layer. As a result, the lubricating layer exhibited significantly improved adhesion resistance compared to a fluid containing only a surfactant and a water-soluble ionic compound. Even when a force of 15 N (approximately 1.5 kg) or more was applied to the catheter, adhesions did not form and the lubricating layer maintained lubrication properties similar to those of human blood vessels. Without the addition of a water-soluble polymer, a lubricating layer capable of withstanding a force of 15 N for more than a few seconds was not formed.

[0023] According to the inventor's evaluation, the lubricating layer formed on the inner surface of the blood vessel model was significantly stronger against the pressing force of the catheter, especially when the three components of a surfactant, a water-soluble ionic compound, and a water-soluble polymer (same molecule) having both hydrophilic and hydrophobic groups were present, and was able to withstand the same level of catheter pressing force as that of a human blood vessel.

[0024] In actual biological blood vessels, catheters and guidewires are designed to slide easily along the inner walls of the blood vessels. In contrast, aneurysm embolization coils and the like are placed inside the body after surgery, and therefore must be kept in a stable position, so they are designed not to slide (move) within biological blood vessels (aneurysms).

[0025] When only a surfactant and a water-soluble ionic compound were added, as in conventional circulatory fluids, the catheter, guidewire, and aneurysm embolization coil inserted into the vascular model all became equally smooth as the amount added increased, and no difference in the tendency for improved lubricity was observed among them.As a result, when the coil was placed inside an aneurysm attached to the vascular model, unlike in actual surgery, the coil continued to move unstably both during and after placement due to catheter manipulation during placement and blood flow after placement.

[0026] In contrast, when three ingredients were added, as in the present invention: a surfactant, a water-soluble ionic compound, and a water-soluble polymer (same molecule) having both hydrophilic and hydrophobic groups, the lubricity of the catheter and guidewire improved (the coefficient of friction decreased significantly) as the amount added increased, but no change was observed in the lubricity of the aneurysm embolization coil (the coefficient of friction remained almost unchanged).As a result, when the aneurysm embolization coil was placed inside an aneurysm formed in a vascular model, the catheters exhibited good lubricity similar to that in living blood vessels, and, just like in actual surgery, the coil was able to maintain a stable position both during and after placement, with almost no movement due to catheter manipulation or blood flow.

[0027] The experimental results clearly demonstrate that the lubrication mechanism of the circulating fluid of the present invention is different from that of conventionally used circulating fluids (containing only surfactants and water-soluble ionic compounds). As a result, by using the circulating fluid of the present invention, it was possible to separately adjust and reproduce the frictional characteristics of catheters and aneurysm embolization coils, and to successfully reproduce the same lubrication characteristics as those found in living blood vessels.

[0028] Another characteristic of the circulating fluid of the present invention is its improved water retention (resistance to drying). The addition of conventional circulating fluids (containing only surfactants or water-soluble ionic compounds) did not have a significant effect on the water retention (resistance to drying) of a liquid (usually water). However, with the circulating fluid of the present invention, a network is formed by the interaction between the surfactant, water-soluble ionic compound, and water-soluble polymer, and water can be stored within the network, resulting in a significant improvement in water retention (resistance to drying).

[0029] Another characteristic is that when the circulating fluid of the present invention is added to a liquid (usually water), the gas dissolved in the liquid does not precipitate on the container holding the liquid or on the surface of an object immersed in the liquid, such as a blood vessel model or a catheter. Even bubbles initially present in the liquid dissolve into the circulating fluid and disappear over time. Furthermore, when a liquid such as water is placed in a sealed container with gaps remaining (a non-liquid-tight container), evaporation of the liquid generally causes clouding on the surface of the gaps. However, when the circulating fluid of the present invention is used, this clouding does not occur (whether the circulating fluid adheres to the gaps and is then removed, or not). Conventional circulating fluids do not affect this bubble generation or adhesion phenomenon (adding a surfactant makes bubbles smaller and more likely to adhere, but does not affect the bubble generation itself, and does not have the effect of trapping and eliminating bubbles in the liquid).

[0030] When using a conventional circulating fluid or no circulating fluid, air bubbles dissolved in the circulating fluid precipitate and adhere to the surface of the object, reducing visibility during catheter simulation. This required periodic removal of the bubbles by stirring or other means. In contrast, when using the circulating fluid of the present invention, no bubbles are generated during the simulation. Air bubbles that were initially present during the preparation stage or that entered the fluid via the catheter automatically disappear. A bubble-free state is naturally formed and maintained in the fluid and on the surface of the object at all times. This significantly improves visibility and eliminates the need for bubble removal, allowing for comfortable surgical simulation. This effect is believed to be useful as a lubricating fluid for applications other than catheter surgery simulation.

[0031] Furthermore, when the lubricating fluid was prepared by adding three components—a surfactant, a water-soluble ionic compound, and a water-soluble polymer (same molecule) with both hydrophilic and hydrophobic groups—as in the present invention, the viscosity of the lubricating fluid increased. When only a surfactant and a water-soluble ionic compound were added to water, as in conventional lubricating fluids, no significant change in viscosity was observed (tap water: 1.25 mPa·s, whereas tap water containing 0.4 wt% surfactant and 2 wt% saturated water containing the water-soluble ionic compound had a viscosity of 1.28 mPa·s). However, when a water-soluble polymer (PVA 1.1 wt%) was further added, the viscosity rose significantly (to 2.91 mPa·s), significantly different from the viscosity of living blood (approximately 1.3 to 1.7 mPa·s). As a result, when a catheter was inserted into the vascular model and a pressure equivalent to blood pressure (120 mmHg) was applied to the circulating fluid filling the vascular model, changes occurred in the flow rate that passed through the catheter and flowed out the other end of the catheter (when an Excelsior 1018 microcatheter was used and 120 mmHg was applied, the flow rate when using the conventional circulating fluid was 0.83 ml / min, and the flow rate when using the lubricating fluid of the present invention was 0.33 ml / min).

[0032] Intensive research was conducted to determine how to reduce the viscosity of a lubricating fluid containing three components, a surfactant, a water-soluble ionic compound, and a water-soluble polymer (same molecule) having both hydrophilic and hydrophobic groups, while maintaining its excellent lubricating properties. As a result, it was discovered that the viscosity could be adjusted by further adding a pH adjuster (buffer) to change the pH, and that a viscosity similar to that of blood could be reproduced even when using the lubricating fluid of the present invention without compromising its excellent lubricating properties (without pH adjuster: pH 6.1, viscosity 2.91 mPa·s; with pH adjuster (carbonate ion, etc.): pH 6.8, viscosity 1.44 mPa·s). This is presumably due to changes in the polymer network formed by the surfactant, water-soluble ionic compound, and the water-soluble polymer having both hydrophilic and hydrophobic groups when the pH adjuster is added. It was also discovered that the pH adjuster can be effectively used to adjust the polymer network formed during use of the lubricating fluid of the present invention.

[0033] Here, the surfactant may be one or more selected from the group consisting of cationic surfactants, anionic surfactants, nonionic surfactants, and zwitterionic surfactants, depending on the material of the catheter sheath, etc. In the above, it is preferable to use deionized water as the water, but tap water may also be used. It is preferable to select the type of surfactant depending on the catheter material. For example, when the sheath is made of Teflon (registered trademark) or polyethylene, which tend to become negatively charged when rubbed, it is preferable to use an anionic surfactant. On the other hand, when the sheath is made of a material that tends to become positively charged, such as polyamide, it is preferable to use a zwitterionic surfactant.

[0034] In endovascular treatment training, it is difficult to determine the charging tendency (e.g., the effects of zeta potential and triboelectric series during triboelectric charging) of materials such as catheter sheaths. When using tap water, the electrolyte composition and amount are not constant, and the pH fluctuates accordingly, making it even more difficult to determine the charging tendency. Therefore, it is preferable to appropriately adjust the type and amount of surfactant added before or during the simulation by confirming the characteristics during actual use. Surfactants can be zwitterionic surfactants alone, cationic surfactants combined with zwitterionic surfactants, or anionic surfactants combined with zwitterionic surfactants. This allows the surfactant to stably adsorb to the surface of the catheter sheath, regardless of the catheter sheath material. The mixing ratio of anionic surfactant (or cationic surfactant) to zwitterionic surfactant is 100:1. quality It is preferable to blend 1 to 100 parts by mass of a zwitterionic surfactant per 1 part by mass of the aqueous solution.

[0035] The concentration of the surfactant can be adjusted as appropriate depending on the type of surfactant, the type and concentration of other solvents, the purpose of use, etc., but is preferably 0.005 mmol / L or more and 100 mmol / L or less. Within this range, low contact resistance is ensured and desirable physical properties as a circulating fluid are obtained (no slimy feeling occurs). Even more preferable is 0.05 mmol / L or more and 10 mmol / L or less.

[0036] The water-soluble ionic compound may be a water-soluble metal salt or a water-soluble ammonium salt (e.g., ammonium chloride or ammonium sulfate), etc. The water-soluble metal salt may be one or more selected from the group consisting of alkali metal salts, alkaline earth metal salts, aluminum salts, and iron salts. Examples of water-soluble alkali metal salts include sodium chloride, potassium chloride, cesium chloride, sodium sulfate, potassium sulfate, cesium sulfate, sodium nitrate, potassium nitrate, and cesium nitrate. Examples of water-soluble alkaline earth metal salts include magnesium chloride, calcium chloride, barium chloride, magnesium nitrate, calcium nitrate, and barium nitrate. Examples of aluminum salts include aluminum chloride, aluminum sulfate, and aluminum nitrate. Examples of iron salts include ferrous chloride, ferric chloride, ferrous sulfate, ferric sulfate, ferrous nitrate, and ferric nitrate. In addition to the above, water-soluble alkali metal salts, alkaline earth metal salts, organic acid salts of metals (e.g., sodium acetate), and complexes can also be used.

[0037] The concentration of the water-soluble metal salt in the circulating fluid is preferably 1 mmol / L or more and 100 mmol / L or less, and more preferably 2 mmol / L or more and 50 mmol / L or less. The function of these water-soluble ionic compounds is unclear, but in the absence of water-soluble ionic compounds, when a large pressing force of 5 N (approximately 0.5 kg) or more is applied to the catheter, the catheter becomes more likely to stick (adhere) to the inner surface of the blood vessel model.

[0038] As the water-soluble polymer having a hydrophilic group and a hydrophobic group, those having both a hydrophilic group and a hydrophobic group in their structure, such as polyvinyl alcohol and methyl cellulose, and complexes thereof can be used. Similar effects were also obtained by mixing a water-soluble polymer material having only hydrophilic groups, such as sodium polyacrylate or carboxymethyl cellulose, with a water-soluble polymer material having only hydrophobic groups, such as alginic acid.The effects of the present invention were not obtained when a water-soluble polymer material having only hydrophilic groups (such as sodium polyacrylate or carboxymethyl cellulose) or a water-soluble polymer material having only hydrophobic groups (such as alginic acid) was used alone. This is thought to be because when the two are dispersed in water, they become entangled and appear to behave as molecules with both hydrophilic and hydrophobic groups. [Brief explanation of the drawings]

[0039] [Figure 1] FIG. 1 is a perspective view of a measuring device for measuring the characteristics of a circulating fluid according to the present invention. [Figure 2] FIG. 2 shows the sinusoidal trajectory of the reciprocating catheter movement measured by the measurement device. [Figure 3] FIG. 3 shows the change in the reaction force on the catheter when the catheter is reciprocated as shown in FIG. [Figure 4] FIG. 4 shows the square wave trajectory of the reciprocating catheter movement measured by the measurement device. [Figure 5] FIG. 5 shows the change in the reaction force against the catheter when the catheter is reciprocated as shown in FIG. 4, compared with the reciprocation speed. [Figure 6] Figure 6 shows the change in the reaction force against the catheter when the catheter is reciprocated as shown in Figure 4 for various circulating fluids. [Figure 7] Figure 7 shows the change in the reaction force against the catheter when the catheter is reciprocated as shown in Figure 4 in various circulating fluids, with the concentrations of the surfactant and water-soluble ionic compound kept constant. [Figure 8] FIG. 8 shows that the reaction force against the catheter is maintained even in a circulating fluid containing sugars. DETAILED DESCRIPTION OF THE INVENTION

[0040] The present inventors created a measurement device 20 shown in FIG. 1 in order to measure the difference in lubricity. The measuring device 20 includes a substrate 21 , a fixing portion 25 and a clip portion 30 . Two pairs of poles 37, 37 are erected on a plastic substrate 21 as the fixing portion 25. The clip portion 30 includes a pair of bars 31, 31 and a pair of elastic sheets 32, 32.

[0041] The pair of bars 31, 31 fixed by the fixing part 25 are urged toward each other by rubber bands 35, 35 when clamping the blood vessel model 5. Elastic sheets 32, 32 are interposed between the bars 31, 31 and the blood vessel model 5. These elastic sheets 32, 32 are set to a thickness of 6 mm and a hardness of HC12.5 to simulate the human aortic wall. The fastening force generated by the rubber bands 35, 35 presses the catheter 1 against the inner surface of the blood vessel model 5 via the bars 31, 31 and the elastic sheets 32, 32, generating the above-mentioned pressing force between the catheter and the inner surface of the blood vessel model.

[0042] The plastic substrate 21 is fixed to the workpiece mounting surface of a general-purpose machine tool. By operating the machine tool, the substrate 21 moves integrally with the workpiece mounting surface. As a result, the entire measuring device 20, excluding the catheter 1, moves in any direction and at any speed according to the operation set by the machine tool. The left end of the catheter 1 inserted into the blood vessel model 5 is connected to a force sensor, which is fixed to the machine tool body or its mounting base so as to move relative to the mounting surface. Note that in this example, the measuring device 20, excluding the catheter 1, is moved by fixing the substrate 21 to the workpiece mounting surface of the machine tool. However, similar measurements can also be performed by fixing the force sensor connected to the catheter 1 to the workpiece mounting surface of the machine tool, fixing the measuring device 20, excluding the catheter 1, in space, and moving the force sensor (i.e., the catheter 1). If a video camera or other device is installed to capture fixed-point images of the fixed part 25, etc., in this configuration, it is recommended that the video camera be fixed to the workpiece mounting surface, similar to the measuring device 20, via a fixture such as a camera arm.

[0043] In this example, the entire measuring device 20, excluding the catheter 1, is reciprocated in a direction perpendicular to the bars 31, 31 (i.e., in the axial direction of the catheter 1). The catheter 1 is fixed to the movable part of the linear slider 3 attached to the base plate 21, and can move only in one direction. This allows the catheter 1 and the entire measuring device 20 to perform a relative linear motion reliably and stably. Furthermore, by sandwiching the vascular model 5 between the bars 31, 31 via the elastic sheets 32, 32, it is possible to reproduce a state in which the blood vessels of the human body are flexibly supported from the surrounding tissues in the living body, and the pressure force of the catheter is widely distributed among the surrounding tissues, thereby enabling the dynamics of the catheter and blood vessels and measurement results to be obtained that are similar to those during actual catheter surgery.

[0044] A circulating fluid (comparison circulating fluid) using the lubricity adjuster introduced in Patent Document 2 (comparison circulating fluid) was prepared by dissolving a surfactant and a water-soluble ionic compound in water, and then dissolving PVA as a water-soluble polymer having both hydrophilic and hydrophobic groups. This circulating fluid was then filled into a silicone rubber vascular model. A catheter with a polyethylene sheath was then inserted into the vascular model, and measurements were performed using the measuring device while applying a sinusoidal reciprocating motion trajectory A shown in Figure 2. The results are shown in Figure 3. This reciprocating motion trajectory A was designed to reproduce the "dithering motion" of the catheter, which vibrates repeatedly at approximately the same position during actual surgery, a motion that is likely to cause adhesions (i.e., loss of the lubrication layer). The small-amplitude section midway along this reciprocating motion trajectory A is specifically designed to simulate this motion. The horizontal axis of Figure 2 represents time, and the change in frequency on the graph indicates that the reciprocating motion of the arm begins slowly, then gradually increases, and then decreases again.

[0045] Here, measurements were performed by adjusting the tension of the rubber band to apply a maximum pressure of 15 N (approximately 1.5 kg) between the catheter and the blood vessel wall, which is the maximum pressure that may be applied to the catheter during an actual surgery. As shown in Figure 3, when a large pressing force of 15 N was applied, the circulating fluid containing no water-soluble polymer (containing only surfactants and water-soluble ionic compounds) generated a very large reaction force of over 10 N on the catheter during reciprocating motion. When this circulating fluid was used, the lubricating layer was lost and adhesions occurred throughout the entire measurement period, and the catheter continued to move in this state. This adhesion occurred when the pressing force exceeded 5 N. In contrast, when the circulating fluid containing surfactants, water-soluble ionic compounds, and water-soluble polymers was added, the lubricating layer was maintained throughout the entire measurement period, and the catheter continued to move in this state with the same lubricity as human blood vessels.

[0046] The results in Figure 3 show that by incorporating PVA, a water-soluble polymer, a strong lubricating layer with excellent lubricity is formed, significantly reducing the frictional resistance between the catheter and the blood vessel model even when a large pushing force is applied to the catheter.

[0047] Figure 5 shows the results of measurements taken using the rectangular wave-shaped reciprocating motion trajectory B shown in Figure 4 to measure the reaction force (insertion force) generated in the catheter during reciprocating motion in a manner that allows comparison with the reciprocating motion speed, and also explains how the measurement data was organized in Figure 6 and subsequent figures. In reciprocating motion trajectory B, the catheter was moved back and forth in steps, and 0.25-second dwells (stopped movement sections) were set at each point indicated by a circle on the graph in Figure 4 to measure the presence or absence and degree of adhesions when the catheter came to a standstill, allowing for evaluation of adhesions after four types of dwell: (1) advancement of the catheter, followed by dwelling and then advancement again, (2) advancement, dwelling and retreat, (3) retreat, dwelling and retreat again, and (4) retreat, dwelling and then advancement. Furthermore, in order to make it easier to distinguish the differences and characteristics of the reaction forces for multiple water-soluble polymers, as shown in Figure 5, the difference (the range indicated by Peak to Peak in Figure 5) between the maximum value of the reaction force (tensile force applied to the catheter) and the minimum value (compressive force applied to the catheter) in each reciprocating cycle (the section combining forward and backward movements) was extracted from the measurement data for each movement speed from 150 mm / min to 7200 mm / min, and a total of 14 numerical values ​​were converted into a numerical group.

[0048] Figure 6 shows measurements performed by applying the rectangular wave-like reciprocating motion trajectory B shown in Figure 4 to the measuring device 20, and the resulting measurement data is presented using the method described above with reference to Figure 5. This figure shows the reaction force (insertion force) applied to the catheter for eight types of circulating fluid, with and without the addition of (1) water, (2) surfactant, (3) water-soluble ionic compound, and (4) water-soluble polymer (PVA). The reaction forces shown in the 14-bar graph in Figure 6 are the peak-to-peak values ​​of the reaction force (catheter insertion force) for each movement speed described with reference to Figure 5. For each group, the bar graphs show the reaction force values ​​at 150, 300, 600, 1200, 1800, 2400, 3000, 3600, 4200, 4800, 5400, 6000, 6600, and 7200 mm / min, starting from the left.

[0049] The measurement results shown in Figure 6 show that, as an overall trend, the reaction force (catheter insertion force) is greater in areas with slower movement speeds than in areas with faster movement speeds. It can be confirmed that this tendency is suppressed by adding an ionic compound. It can also be confirmed that ionic compounds alone do not exhibit lubricity. It can also be confirmed that the lubricity obtained by surfactants and water-soluble polymers is enhanced by adding ionic compounds.

[0050] Furthermore, the results in Figure 6 show that the circulating fluid to which both a surfactant and a water-soluble polymer were added generates a larger reaction force than the circulating fluid to which only the water-soluble polymer was added, confirming that not only was the synergistic effect of the mixed addition not obtained, but also that the lubricity of the water-soluble polymer was impaired by the mixture. It was confirmed that the circulating fluid to which three types of additives - surfactant, ionic compound, and water-soluble polymer - had been added produced a significant synergistic effect on lubrication without impairing the properties of each of them.

[0051] Unlike the sine wave trajectory A (Figure 2), measurements using this square wave trajectory B (Figure 4) do not reveal the toughness of the lubricating layer as a characteristic feature in the measurement results. Therefore, although the difference appears small, the lubricating layer toughness of the liquid with the three additives added is significantly improved compared to the other circulating fluids. This difference in the toughness of the lubricating layer can be explicitly measured using a measurement method using the sine wave trajectory A (Figure 2, dither). When the toughness is low, the lubricating layer breaks down in the section where the amplitude of the sine wave trajectory A becomes smaller, causing direct contact between the catheter and the inner surface of the blood vessel model, resulting in a protruding, large reaction force in the same section.

[0052] Figure 7 shows the results of measurements taken using the same method as in Figure 6 for circulating fluids obtained by changing the type of water-soluble polymer while keeping the concentrations of the surfactant and water-soluble ionic compound constant. In FIG. 7, No. 1 is a circulating fluid containing no water-soluble polymer, but containing only a surfactant and a water-soluble ionic compound. The water-soluble polymer blended in No. 2 was PVA (semi-saponified type), and the amount added was 0.8 wt%. The water-soluble polymer blended in No. 3 was PVA (fully saponified type), and the amount added was 0.8 wt%. The water-soluble polymer blended in No. 4 was PVA (degree of polymerization 2000), and the amount added was 0.8 wt%. The water-soluble polymer blended in No. 5 was PVA (degree of polymerization 500), and the amount added was 0.8 wt%. The water-soluble polymer blended in No. 6 was PVP, and the amount added was 0.8 wt%. The water-soluble polymer blended in No. 7 was vinyl acetate, and the amount added was 0.8 wt%. The water-soluble polymer blended in No. 8 was PEG (molecular weight 200), and the amount added was 0.8 wt%. The water-soluble polymer blended in No. 9 was PEG (molecular weight 200), and the amount added was 1.6 wt%. The water-soluble polymer blended in No. 10 was PEG (molecular weight 200), and the amount added was 4.0 wt%. The water-soluble polymer blended in No. 11 was PEG (molecular weight 200), and the amount added was 8.0 wt%. The water-soluble polymer blended in No. 12 was PEG (molecular weight 200), and the amount added was 16.0 wt%. The water-soluble polymer blended in No. 13 was PEG (molecular weight 1000), and the amount added was 0.8 wt%. The water-soluble polymer blended in No. 14 was PEG (molecular weight 2000), and the amount added was 0.8 wt%. The water-soluble polymer blended in No. 15 was PEG (molecular weight 6000), and the amount added was 0.8 wt%. The water-soluble polymer blended in No. 16 is hyaluronic acid, and the amount added is 0.8 wt%. The water-soluble polymer blended in No. 17 is guar gum, and the amount added is 0.8 wt%. The water-soluble polymer blended in No. 18 was xanthan gum, and the amount added was 0.8 wt%. The water-soluble polymer blended in No. 19 was carrageenan, and the amount added was 0.8 wt%. The water-soluble polymers blended in No. 20 were carrageenan and sodium polyacrylate, with a total addition amount of 0.8 wt%. The water-soluble polymer blended in No. 21 was sodium alginate, and the amount added was 0.8 wt%. The water-soluble polymer blended in No. 22 was alginic acid, and the amount added was 0.8 wt%. The water-soluble polymer blended in No. 23 was alginic acid + sodium polyacrylate, and the amount added was 0.8 wt%. The water-soluble polymer blended in No. 24 was sodium polyacrylate, and the amount added was 0.8 wt%. The water-soluble polymer blended in No. 25 is carboxymethyl cellulose, and the amount added is 0.8 wt%. The water-soluble polymer blended in No. 26 was methylcellulose, and the amount added was 0.8 wt%.

[0053] The measurement results shown in Figure 7 confirm the following: The effects of the present invention are realized when water-soluble polymers having both hydrophilic and hydrophobic groups, such as PVA (Nos. 2 to 5) and methyl cellulose (No. 26), are used, resulting in a significant improvement in lubrication. In this state, the toughness of the lubricating layer is also significantly improved for each circulating fluid. As can be seen from No. 3, industrially used PVA is not fully saponified, so even fully saponified PVA has both hydrophilic and hydrophobic groups, and thus exhibits the effects of the present invention by itself.

[0054] On the other hand, it is clearly confirmed that the effects of the present invention are not exhibited at all when using water-soluble polymers such as Nos. 6 to 22 and Nos. 24 and 25, which have only hydrophilic groups or only hydrophobic groups (including hydrophilic or hydrophobic groups resulting from molecular arrangement, etc.). In particular, it is confirmed that when water-soluble polymers such as Nos. 6 to 22 and Nos. 24 and 25 are added, lubricity is significantly reduced compared to when they are not added (No. 1). Furthermore, as can be seen from the results of No. 23, when No. 22 (having only hydrophobic groups) and No. 24 (having only hydrophilic groups), which do not exhibit the effects of the present invention when used alone, are added together, the effects of the present invention are significantly exhibited.

[0055] In this specification, the term "water-soluble polymer" refers to a polymer that dissolves in water, and includes not only those that dissolve alone, such as PVA, but also those that become water-soluble when dissolved in a water-soluble solvent (such as crosslinked products of PVA and polysaccharides dissolved therein). For example, alginic acid No. 22 contains only hydrophobic groups and is therefore insoluble in water by itself, but becomes soluble in water when added together with PVA Nos. 2 to 5.

[0056] The effects of the present invention can be further refined by blending multiple types of surfactants, water-soluble ionic compounds, and water-soluble polymers, taking into account the type and material of the catheter used, allowing for more precise adjustment of lubrication properties (including their relationship to catheter movement speed) and zeta potential trends. This allows for improved functionality and the creation of circulating fluids tailored to specific purposes and conditions. Figure 8 shows an example of measurements performed using the same method as Figure 6 using a circulating fluid (far right in Figure 8) designed to maintain a constant reaction force on the catheter regardless of catheter movement speed. In this example, an anionic surfactant (0.2 wt%) and a zwitterionic surfactant (0.12 wt%) were used in combination, and PVA (0.32 wt%), alginate (0.08 wt%), and fructose (0.45 wt%) were used as water-soluble polymers. A pH buffer (0.02 wt%) was also added to approximate the zeta potential trends of living blood and to bring the catheter's characteristics closer to those of human blood vessels.

[0057] Furthermore, the results in Figure 8 confirm that the effects of the present invention are not lost by adding sugars. If PVA is added alone as a water-soluble polymer, the remaining PVA will form a film when the circulating fluid containing it dries, and this film may clog or adhere to the inside of the vascular model or to equipment such as catheters and pumps, causing problems in subsequent use. However, when sugars are added, a polymer film does not form during drying, and the product becomes a fine powder, which can be easily cleaned by wiping.

[0058] Heating and cooling the circulating fluid can sometimes change the molecular bonding state and size, allowing for adjustments to the lubrication properties. For example, in the case of a circulating fluid containing PVA, heating it at a specified temperature (e.g., 35°C) for a specified time (e.g., 2 minutes) removed turbidity, increased transparency, and significantly improved lubrication properties compared to before heating. The circulating fluid whose turbidity had been removed by heating irreversibly maintained its high transparency and excellent lubricity even after being returned to room temperature (approximately 25°C).

[0059] When using water-soluble polymers such as PVA, it is preferable to maintain the pH of the circulating fluid in the range from weakly basic to weakly acidic to mimic the environment of blood. Therefore, a pH buffer can be added to the circulating fluid as an auxiliary agent. In particular, when an acidic circulating fluid with a pH below 5.0 was used, the hydrophilic coating on the catheter surface was inactivated within a short period of time, resulting in adverse effects such as a significant decrease in the lubricity of the catheter.

[0060] According to the inventors' investigations, after the circulating fluid containing the water-soluble polymer of each example was brought into contact with the inner wall of the blood vessel model and the outer periphery of the catheter sheath, good lubrication was maintained between the blood vessel model and the catheter even when another circulating fluid (for example, one containing only a surfactant) was used. This is because the circulating fluid of the example formed a layer of water-soluble polymer material on at least the inner periphery of the blood vessel model. In other words, it is believed that the circulating fluid in each example forms some kind of lubricating layer on the surface of the silicone rubber and the surface of the resin material that makes up the sheath, and that this layer is maintained to provide lubricity. Sequestering agents (chelating agents) were effective in cleaning and removing the remaining lubricating layer. Examples of chelating agents that can be used include edetate salts.

[0061] When forming a blood vessel model from silicone rubber, if many unreacted portions remain in the siloxane molecules that make up the silicone rubber, the lubricating function of the present invention will not be fully effective. Therefore, the effects of the present invention can be further enhanced by promoting the reaction by heating, etc. to reduce the unreacted portions, or by using a TMS agent (trimethylsilylating agent) or the like to chemically modify the unreacted portions of the silicone rubber with functional groups such as hydroxyl groups, carboxyl groups, and amino groups.

[0062] Therefore, the present invention can be expanded as follows. (1) A lubricant that provides lubricity between a first member including a crosslinked polymeric material and a second member including a crosslinked polymeric material, A lubricant comprising one or more selected from the group consisting of water, a surfactant, a water-soluble ionic compound, a first water-soluble polymer having a hydrophilic group and a hydrophobic group, a mixture of a second water-soluble polymer having a hydrophilic group and a third polymer having a hydrophobic group, and a mixture of the first water-soluble polymer and the third polymer. An example of the first member is a blood vessel model made of silicone rubber, urethane rubber, or the like, and an example of the second member is a catheter sheath made of polyethylene or the like. This lubricity regulator is not limited to the combination of a blood vessel model and a catheter, but improves the lubricity between crosslinkable polymer materials. (2) The lubricant according to (1), wherein the surfactant comprises an amphoteric surfactant. (3) The lubricant according to (1) or (2), wherein the water-soluble polymer comprises polyvinyl alcohol. (4) The lubricant according to (3), wherein the water-soluble polymer is a crosslinked product of polyvinyl alcohol and polysaccharide. (5) The lubricant according to (4), further comprising a monosaccharide. (6) The lubricant according to (1), further comprising a pH adjuster.

[0063] Such lubricants are useful as surface coatings for catheters. That is, (11) A lubricant to be applied to the surface of a catheter sheath, comprising one or more selected from the group consisting of water, a surfactant, a water-soluble ionic compound, a first water-soluble polymer having both a hydrophilic group and a hydrophobic group, a mixture of a second water-soluble polymer having a hydrophilic group and a third polymer having a hydrophobic group, and a mixture of the first water-soluble polymer and the third polymer. (12) The lubricant according to (11), wherein the surfactant comprises an amphoteric surfactant. (13) The lubricant according to (11) or (12), wherein the water-soluble polymer contains polyvinyl alcohol. (14) The lubricant according to (13), wherein the water-soluble polymer is a crosslinked product of polyvinyl alcohol and polysaccharide. (15) The lubricant according to (14), further comprising a monosaccharide. (16) The lubricant according to (11), further comprising a pH adjuster. (17) A catheter having a membrane formed from any one of the lubricants (11) to (16).

[0064] The measuring device shown in Figure 1 is a newly created device for evaluating the lubricity between a blood vessel model and a catheter. The invention of this device can be understood as follows. (21) An apparatus for evaluating the lubricity between a blood vessel model and a catheter, comprising: a clipping unit that clips the blood vessel model via an elastic material in a state where the catheter is inserted into the blood vessel model; a fixing portion that fixes the clip portion; a catheter driving unit that moves the catheter in the axial direction of the blood vessel model at a predetermined rhythm; a resistance measuring unit that measures the resistance applied to the catheter driving unit when the catheter is moved. (22) The measuring device according to (21), wherein the elastic modulus of the elastic material is equal to the elastic modulus of human tissue. (23) The measuring device according to (22), wherein the elastic material is made of silicone gel. (24) The measuring device according to any one of (21) to (23), wherein the catheter driving unit varies the moving speed of the catheter.

[0065] The present invention is not limited to the above-described embodiments and examples, and various modifications within the scope of the claims and within the scope that can be easily conceived by a person skilled in the art are also included in the present invention. The following items are disclosed below: (101) A water-based circulating fluid used in a catheter simulator, the circulating fluid containing one or more selected from a first water-soluble polymer having both hydrophilic and hydrophobic groups, a mixture of a second water-soluble polymer having a hydrophilic group and a third polymer having a hydrophobic group, and a mixture of the first water-soluble polymer and the third polymer. (102) The circulating fluid according to (101), wherein the water-soluble polymer is contained in an amount of 0.5 to 8.0% by mass relative to the water content of the circulating fluid. (103) The circulating fluid according to (101), wherein the first water-soluble polymer is one or more selected from natural polymers such as PVA (polyvinyl alcohol), methyl cellulose, proteins, and starch, as well as synthetic polymers such as polyacrylic acid, polyacrylamide, polyethylene oxide, poly(vinylpyrrolidone), polyvinylamide, and polyamines. (104) The circulating fluid according to (101), wherein the first water-soluble polymer is PVA or methyl cellulose. (105) The circulating fluid according to (104), wherein the first water-soluble polymer is PVA. (106) The circulating fluid according to (105), wherein the PVA has a number average molecular weight of 500 to 2000 and a degree of saponification of 75 or more. (107) The circulating fluid according to (105), further comprising a pH buffering agent. (108) The circulating fluid according to (105), further containing a sugar. (109) The circulating fluid according to (108), wherein 50 to 200 parts by mass of a sugar is blended with 100 parts by mass of the PVA. (110) The blending ratio of the second water-soluble polymer and the third polymer in the mixture is The circulating fluid according to (101), wherein the ratio is 1:1. (111) The circulating fluid according to (101), wherein the second water-soluble polymer is sodium polyacrylate and the third polymer is alginic acid. (112) The circulating fluid according to (101), further comprising a surfactant and a water-soluble ionic compound. (113) The circulating fluid according to (110), further comprising a pH buffer. (114) The circulating fluid according to (110), wherein the surfactant is a zwitterionic surfactant alone, a cationic surfactant plus a zwitterionic surfactant, or an anionic surfactant plus a zwitterionic surfactant. (115) A lubricity adjuster to be blended into an aqueous circulating fluid used in a catheter simulator, comprising: A lubricity adjuster comprising one or more selected from a first water-soluble polymer having both a hydrophilic group and a hydrophobic group, a mixture of a second water-soluble polymer having a hydrophilic group and a third polymer having a hydrophobic group, and a mixture of the first water-soluble polymer and the third polymer. (116) A first aqueous solution containing the lubricity modifier according to (113), a second aqueous solution containing a surfactant; and a third aqueous solution containing a water-soluble ionic compound. (117) circulating the circulatory fluid according to (101) through a blood vessel model; and inserting a catheter into the blood vessel model. (118) The method according to (115), further comprising the step of chemically modifying functional groups of the silicone rubber before circulating the circulating fluid when the vascular model is formed of silicone rubber. (119) A cleaning method, comprising removing the catheter according to (115) from the blood vessel model and then cleaning it with a cleaning solution containing a chelating agent. (120) 1. A water-based lubricity adjuster that provides lubricity between a first component comprising a crosslinked polymeric material and a second component comprising a crosslinked polymeric material, A lubricity adjuster comprising one or more selected from a first water-soluble polymer having both a hydrophilic group and a hydrophobic group, a mixture of a second water-soluble polymer having a hydrophilic group and a third polymer having a hydrophobic group, and a mixture of the first water-soluble polymer and the third polymer. (121) The lubricity regulator according to (118), wherein the first member is a blood vessel model and the second member is a catheter sheath. (122) water, surfactants, water-soluble ionic compounds, and An aqueous composition comprising one or more polymers selected from a first water-soluble polymer having both a hydrophilic group and a hydrophobic group, a mixture of a second water-soluble polymer having a hydrophilic group and a third polymer having a hydrophobic group, and a mixture of the first water-soluble polymer and the third polymer. (223) An aqueous circulating fluid used in a catheter simulator having a blood vessel model, the fluid comprising a first water-soluble polymer having both a hydrophilic group and a hydrophobic group, a surfactant, and a water-soluble ionic compound, wherein the first water-soluble polymer forms a lubricating layer on the inner circumferential surface of the blood vessel model by having its polymer chains intricately entangled; preparing a stock solution of a circulating fluid, the first water-soluble polymer being polyvinyl alcohol; Heating the stock solution to increase its clarity; A method for producing a circulating fluid comprising:

[0066] I would like to express my heartfelt gratitude to my father, Moritaka Ikeda, who always enthusiastically and kindly supported me in every aspect of the process of this invention, including the design, prototyping, and experiments of measuring devices and methods. I would like to dedicate this patent, which I have finally been able to apply for, to him. [Explanation of symbols]

[0067] 1 catheter 5. Vascular model 20 Measuring Equipment

Claims

1. An aqueous circulating fluid used in a catheter simulator equipped with a blood vessel model, the circulating fluid comprising a mixture of a second water-soluble polymer having a hydrophilic group and a third polymer having a hydrophobic group, or a mixture of a first water-soluble polymer having both a hydrophilic group and a hydrophobic group and the third polymer.

2. The blending ratio of the second water-soluble polymer and the third polymer in the mixture is 2. The circulating fluid according to claim 1, wherein the ratio is 1:

1.

3. 2. The circulating fluid according to claim 1, wherein the second water-soluble polymer is sodium polyacrylate and the third polymer is alginic acid.

4. The circulating fluid according to claim 1 , further comprising a surfactant and a water-soluble ionic compound.

5. 5. The circulating fluid according to claim 4, further comprising a pH buffer.

6. 5. The circulating fluid according to claim 4, wherein the surfactant is a zwitterionic surfactant alone, a cationic surfactant plus a zwitterionic surfactant, or an anionic surfactant plus a zwitterionic surfactant.

7. A lubricity adjuster to be blended into an aqueous circulating fluid used in a catheter simulator, comprising: A lubricity adjuster comprising a mixture of a second water-soluble polymer having a hydrophilic group and a third polymer having a hydrophobic group, or a mixture of a first water-soluble polymer having both a hydrophilic group and a hydrophobic group and the third polymer.

8. A first aqueous solution containing the lubricity modifier according to claim 7; a second aqueous solution containing a surfactant; and a third aqueous solution containing a water-soluble ionic compound.

9. circulating the circulating fluid according to claim 1 through a blood vessel model; and inserting a catheter into the blood vessel model.

10. The method according to claim 9, further comprising the step of chemically modifying functional groups of the silicone rubber before circulating the circulating fluid when the blood vessel model is made of silicone rubber.

11. A cleaning method, comprising: after executing the catheter simulation method according to claim 9, extracting the catheter from the blood vessel model; and then cleaning the catheter with a cleaning solution containing a chelating agent.

12. water, surfactants, water-soluble ionic compounds, and An aqueous composition comprising a mixture of a second water-soluble polymer having a hydrophilic group and a third polymer having a hydrophobic group, or a mixture of a first water-soluble polymer having both a hydrophilic group and a hydrophobic group and the third polymer.

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