Bubble removal cap

Abstract

To achieve a bubble removal cap having improved operability.SOLUTION: A bubble removal cap 100 comprises a cylindrical housing 110 having a connector portion 111 to which a syringe member is connected on a proximal end side, and a filter 120 fixed on a distal end side relative to the connector portion 111 of the housing 110, the filter 120 having a plurality of pores and a water-absorbing polymer that swells upon contact with a liquid to close the pores, wherein the filter 120 includes a first layer 121 provided on the proximal end side and permeable to the liquid, and a second layer 122 provided on the distal end side, containing the water-absorbing polymer in a larger amount than the first layer 121, and blocking permeation of the liquid.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a bubble removal cap. [Background technology]

[0002] Gas components in a patient's arterial blood are analyzed to determine the status of organs such as the lungs, heart, and kidneys, as well as bodily fluids. To perform arterial blood gas analysis, arterial blood is collected from the patient's radial artery or other arteries. A dedicated syringe equipped with a vent filter that allows air to pass through but not liquids can be used to collect arterial blood. By puncturing the artery, arterial blood flows into the syringe, and air within the syringe is pushed out through the vent filter. When blood fills up to the vent filter, the vent filter closes, stopping the inflow of blood and completing the blood collection process.

[0003] If air bubbles remain in the syringe after blood collection, they will affect gas analysis. For this reason, air bubbles are removed from the syringe after blood collection. After blood collection, the syringe is turned upright to collect the air bubbles near the nozzle, and the bubbles can be pushed out of the nozzle by pressing the plunger. However, when the air bubbles are pushed out, a small amount of blood is also pushed out. Blood pushed out of the nozzle can cause medical accidents, such as infection.

[0004] To push out air bubbles while avoiding contamination by blood, a bubble removal cap has been proposed, consisting of a housing that can be attached to the syringe nozzle and a filter attached to the tip of the housing that loses its air and liquid permeability when it comes into contact with blood. By collecting air bubbles on the nozzle side and pressing the plunger, the air bubbles are first sent into the bubble removal cap attached to the nozzle, and then the blood flows in. The air bubbles sent in first pass through the filter and are removed to the outside. When the housing is subsequently filled with blood, the filter closes, allowing only the air bubbles to be removed without leaking blood to the outside (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 4-231967 Summary of the Invention [Problem to be solved by the invention]

[0006] However, conventional bubble removal caps have the problem of requiring extremely careful operation: if the plunger is pressed with a small amount of force, blood may rush into the housing, causing the blood to penetrate the filter before the air bubbles can pass through, resulting in the filter losing its breathability.

[0007] An object of the present disclosure is to realize a bubble removal cap with improved operability. [Means for solving the problem]

[0008] One embodiment of the bubble removal cap of the present disclosure comprises a cylindrical housing having a connector portion at the base end to which a syringe member is connected, and a filter fixed to the housing further distally than the connector portion and having a plurality of pores and a water-absorbent polymer that swells upon contact with liquid to block the pores, the filter having a first layer provided at the base end that is permeable to liquid, and a second layer provided at the distal end that contains more water-absorbent polymer than the first layer and prevents liquid from passing through.

[0009] In one embodiment of the bubble removal cap, the filter has a first layer and a second layer with different distributions of water-absorbent polymer, and the second layer at the tip side is responsible for reliably preventing the passage of blood. Therefore, even if blood flows forcefully from the syringe member into the housing and comes into contact with the filter, the blood is less likely to immediately penetrate the interior, and breathability is less likely to be lost. Therefore, it is less likely that a situation will occur in which the filter becomes clogged before air bubbles are removed due to incorrect plunger operation, resulting in a failed bubble removal operation, and operability can be greatly improved.

[0010] In one embodiment of the bubble removal cap, the filter is a porous sintered resin filter that is press-fitted into the housing and compressed in the radial direction. With this configuration, the filter is compressed and the pores become narrower, making it less likely for blood to leak.

[0011] In one embodiment of the bubble removal cap, the housing allows the filter to be visually inspected, and the first and second layers can be different colors. This configuration makes it easy to visually confirm that blood has reached the second layer. This reduces the likelihood of operating errors, such as leaving the second layer in a state where the pores of the second layer are not blocked and the filter's breathability is not lost. It also reduces the likelihood of incorrect orientation when assembling the filter to the housing, facilitating inspection. [Effects of the Invention]

[0012] The bubble removal cap of the present disclosure is less likely to fail during the bubble removal operation, and allows the bubble removal operation to be performed easily. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 2 is a cross-sectional view showing an air bubble removal cap according to one embodiment. [Figure 2] (a) to (e) are photographs showing the bubble removal cap in use in sequence. DETAILED DESCRIPTION OF THE INVENTION

[0014] 1, an embodiment of the bubble removal cap 100 includes a cylindrical housing 110 and a filter 120 fixed inside the housing. The housing 110 includes a connector portion 111 provided on the base end side to which a syringe member is connected, and a bubble removal portion 112 provided on the tip end side. A partition wall 115 having a liquid passage 116 is provided between the connector portion 111 and the bubble removal portion 112.

[0015] The connector portion 111 can have various configurations that allow it to be liquid-tightly connected to the tip nozzle of the syringe member. If the tip nozzle is a male luer connector, the connector portion 111 can be a female luer connector. It can also be configured to be connected to the tip nozzle via another member. When the tip nozzle or the like is connected, a small space 131 is created on the tip side of the connector portion 111, including the liquid passage 116.

[0016] A filter 120, which loses its breathability upon contact with liquid, is fixed to the bubble removal unit 112 at a distance from the partition wall 115, and a bubble separation space 132 is provided between the partition wall 115 and the filter 120. When blood containing bubbles is pushed out from the syringe member connected to the connector unit 111, the filter 120 is breathable before contacting the blood, so the air in the space 131 and the bubble separation space 132 is pushed out toward the tip side through the filter 120. At this time, the air that forms the bubbles is also pushed out, so the bubbles are removed. When the bubble separation space 132 is filled with blood and the filter is completely wet with blood, the filter 120 loses its breathability, so the blood inside the bubble removal cap 100 and the syringe member is kept airtight and liquid-tight and is isolated from the outside air.

[0017] If blood is forcefully ejected from the nozzle due to, for example, an incorrect operation of the syringe plunger, the base end surface of filter 120 may come into contact with blood before space 131 and bubble separation space 132 are filled with blood. However, filter 120 of this embodiment has, on the distal side, a second layer 122 having pores that allow blood to pass through and a water-absorbent polymer evenly distributed therein, which loses blood permeability upon contact with blood, while on the proximal side, a first layer 121 having pores that allow blood to pass through and which does not contain a water-absorbent polymer or in which the water-absorbent polymer is only locally distributed compared to the second layer, which does not lose blood permeability even upon contact with blood. In conventional filters, the water-absorbent polymer is evenly distributed throughout the filter, so that if blood comes into contact with the base end side of the filter due to an incorrect operation, the water-absorbent polymer immediately blocks the pores, rapidly losing breathability. However, filter 120 of this embodiment forms first layer 121 and second layer 122 with different distribution states of the water-absorbent polymer, giving second layer 122 the function of reliably preventing the passage of blood, and giving first layer 121 the function of a buffer that delays the arrival of blood at second layer 122. As a result, it is possible to alleviate the conditions under which breathability is lost while reliably preventing the passage of blood, and the risk of failure in removing bubbles is reduced.

[0018] The filter 120 can be, but is not limited to, a filter made of a sintered resin having pores containing a water-absorbing polymer that swells upon absorption of water. Specifically, a filter 120 having a first layer 121 and a second layer 122 can be obtained by providing a layer with a high water-absorbing polymer content at the distal end of a sintered resin filter. The first layer 121 preferably does not contain water-absorbing polymer, but it can also be formed by lowering the content sufficiently or making it present only locally. On the other hand, the second layer 122 has a sufficiently higher and more evenly distributed water-absorbing polymer content than the first layer 121. Upon contact with liquid, the water-absorbing polymer immediately draws blood into the filter, causing the water-absorbing polymer to swell and clog the pores. This prevents liquid penetration and immediately eliminates the breathability of the filter upon contact with liquid.

[0019] The resin sintered body can be made of various materials having minute pores, such as polyethylene, polypropylene, polymethyl methacrylate, polystyrene, etc. The water-absorbing polymer can be made of various materials, such as starch graft polymers, acrylic polymers, and polyvinyl alcohol polymers.

[0020] The content of the water-absorbent polymer in the second layer 122 can be selected appropriately depending on the porosity of the resin sintered body, etc., but from the viewpoint of preventing blood penetration and losing breathability when exposed to blood, it is preferable that the content be approximately 1% to 20% of the total weight of the second layer 122. The first layer 121 can be a layer that does not contain a water-absorbent polymer, or a layer that contains a water-absorbent polymer in an amount that does not hinder liquid penetration. For example, the first layer 121 can be a layer that contains less than 1% of the water-absorbent polymer. For example, the first layer 121 can be configured so that the base end side does not contain a water-absorbent polymer and the vicinity of the boundary with the second layer 122 contains a water-absorbent polymer.

[0021] A resin sintered body is preferable because it has suitable elasticity and rigidity and can be easily assembled into the housing 110 by press-fitting. Forming a portion in the bubble removal portion 112 whose inner diameter is slightly smaller than the outer diameter of the filter 120 and assembling the filter 120 by press-fitting the filter 120 allows the filter 120 to be held in the bubble removal portion 112 in a radially compressed state, facilitating a sealed structure. Compression reduces the pore size of the filter 120, thereby reducing leakage and lengthening the time it takes for blood to permeate the first layer 121. This reduces the likelihood of blood reaching the second layer 122, which has a high water absorption capacity, before the bubbles are removed. The inner surface of the bubble removal portion 112 can also be tapered, with a diameter that narrows toward the distal end. This further compresses the filter 120 toward the distal end, further narrowing the pores in the second layer 122, which contains a water-absorbent polymer, and more reliably closing the pores.

[0022] In this embodiment, a ring-shaped step 135 is formed on the inner wall surface of the bubble removal section 112, preventing the filter 120 from being pushed over the step 135 toward the base end. Furthermore, the position of the filter 120 is determined by the step 135, which makes it easy to keep the distance between the filter 120 and the partition wall 115 constant and to determine the volume of the bubble removal space 132. Note that the step 135 may not be ring-shaped but may be discontinuous or may be a recessed groove. Alternatively, a configuration without a step or the like may be used.

[0023] The method of assembling the filter 120 into the housing 110 is not limited to press-fitting, but various methods such as welding and adhesive bonding can be used. Furthermore, the filter 120 is not limited to a sintered resin body, but can also be a ceramic filter, a glass fiber filter, a membrane filter, or the like.

[0024] The filter 120 having the first layer 121 and the second layer 122 can be formed by various methods, but for example, by filling a mold with the resin of the first layer and the resin of the second layer in that order and heating it, it is possible to obtain an integrally formed filter 120 having the second layer 122 on the tip side of the first layer 121. In this case, there is a possibility that the water-absorbent polymer is also carried in the pores of the first layer 121, but the content can be kept sufficiently lower than that of the second layer 122, and the permeability of the first layer 121 to liquids and gases can be ensured.

[0025] The filter 120 can also be formed by laminating together a resin sintered body containing a water-absorbent polymer and a resin sintered body not containing the water-absorbent polymer that have been molded separately. The resin sintered body not impregnated with a water-absorbent polymer that will become the first layer 121 and the resin sintered body carrying a water-absorbent polymer that will become the second layer 122 can be integrated by laminating them together by heat welding, ultrasonic welding, adhesive, etc. The two resin sintered body filters can also be simply stacked on top of each other without being laminated together.

[0026] The first layer 121 and the second layer 122 can be made of different materials. For example, the second layer 122 made of a resin sintered body carrying a water-absorbent polymer and the first layer 121 which is a membrane filter can be bonded or stacked together. The first layer 121 can also be a relatively coarse filter such as filter paper, a nonwoven fabric filter, or a mesh filter. Conversely, the first layer 121 can be made of a porous resin sintered body, and the second layer 122 can be made of another material.

[0027] When the first layer 121 and the second layer 122 are made of sintered resin, it is preferable to ensure a certain thickness in order to prevent loss of breathability before the bubble separation space 132 is filled with blood and to prevent blood from passing through the filter 120. To prevent a sudden loss of breathability, the first layer 121, which is a sintered resin that does not contain a water-absorbent polymer, is preferably 1 mm or more. To prevent blood from passing through the filter, the second layer 122, which is a sintered resin that contains a water-absorbent polymer, is preferably 2 mm or more. To make the product compact, the first layer 121 is preferably 3 mm or less, and the second layer 122 is preferably 3.5 mm or less. The thicknesses of the first layer 121 and the second layer 122 can be the same or different.

[0028] In this embodiment, the housing 110 is transparent or translucent to allow visual observation of the interior, and the first layer 121 and the second layer 122 are different colors so that they can be clearly distinguished visually. If the filter 120 is left unattended before blood reaches the second layer 122, the second layer 122 remains breathable, which could result in the blood not being isolated from the outside air and potentially distorting the results of the gas analysis. Furthermore, the lack of a distal end creates a risk of blood leaking from the proximal end. By making the first layer 121 and the second layer 122 visually distinguishable, it is possible to visually confirm that blood has reached the second layer 122, thereby reducing the likelihood of the second layer 122 being left unattended without losing its breathability. Making the first layer 121 and the second layer 122 visually distinguishable also helps prevent incorrect orientation when assembling the filter 120 to the housing 110 and facilitates inspection.

[0029] The colors of the first layer 121 and the second layer 122 are not particularly limited, but for example, the first layer 121 can be white and the second layer 122 can be light blue. Such a color scheme not only makes it easy to distinguish between the first layer 121 and the second layer 122, but also makes it easy to see how far the blood has reached because it is different from the color of blood. Aside from this color scheme, it is preferable that the first layer 121 and the second layer 122 have significantly different brightnesses or are opposite colors. From the viewpoint of making it easy to see where the blood front has reached, a color other than red is preferable.

[0030] Instead of changing the colors of the entire first layer 121 and the second layer 122, it is also possible to make it possible to confirm that blood has reached the second layer 122 by changing the color of the boundary portion or by providing a gap between the first layer 121 and the second layer 122. In addition, the boundary portion between the first layer 121 and the second layer 122 can be indicated by providing a marker line or the like on the housing 110 side rather than the filter 120 side.

[0031] In this embodiment, a partition 115 is provided between the connector section 111 and the bubble removal section 112, and a small-diameter liquid passage 116 is provided in the partition 115. By having the blood pass through the narrow liquid passage 116 before flowing into the bubble separation space 132, it is possible to make it difficult for the blood on the bubble separation space 132 side to return to the connector section 111 side. Therefore, even if a small number of bubbles remain in the bubble separation space 132, they are less likely to affect the blood in the syringe member, thereby improving the accuracy of gas analysis. Providing the partition 115 also improves the strength of the housing 110.

[0032] In this embodiment, the filter 120 is fixed to the housing 110 with a gap between it and the tip of the housing 110. Providing a tip space 133 between the filter 120 and the tip of the housing 110 makes it difficult for an operator's fingers to touch the filter 120. This makes it difficult for the filter 120 to be contaminated or damaged by touching it before use. Furthermore, even if blood passes through the filter 120 or a leak occurs, the risk of coming into contact with blood can be reduced.

[0033] 2(a) to 2(e) show examples of using the bubble removal cap of this embodiment. As shown in FIG. 2(a), the second layer 122 of the filter 120 is darker in color than the first layer 121, making the first layer 121 and second layer 122 visually distinguishable. When a syringe member is connected to the connector portion 111 and the plunger is pressed, the space 131 within the connector portion 111 is filled with blood. Further pressing of the plunger causes blood to flow through the fluid passage 116 into the bubble separation space 132. In the state shown in FIG. 2(b), blood reaches the first layer 121 of the filter 120 before the bubble separation space 132 is completely filled with blood.

[0034] In this state, blood is in partial contact with the surface of the first layer 121, but the first layer 121 is not entirely wet, and blood has not penetrated into the interior. Because the breathability of the second layer 122 is maintained, air bubbles along with the air in the air bubble separation space 132 pass through the filter 120 and are pushed toward the distal end, and the air bubble separation space 132 becomes completely filled with blood (FIG. 2(c)). Because the first layer 121 is permeable to blood, blood penetrates into the entire first layer 121, as shown in FIG. 2(d). Finally, as shown in FIG. 2(e), the blood penetrates the first layer 121 and reaches the second layer 122. The blood that reaches the second layer 122 swells the water-absorbent polymer and blocks the pores, preventing the blood from moving further toward the distal end, and breathability is completely lost.

[0035] The bubble removal cap 100 of this embodiment can be combined with a syringe member having a filter gasket used for collecting arterial blood, but can also be combined with a regular syringe member. Furthermore, the cap can be used to remove bubbles not only from arterial blood but also from various liquids. [Industrial Applicability]

[0036] The bubble removal cap of the present disclosure is less likely to fail during the bubble removal operation, allows the bubble removal operation to be performed easily, and is useful in the medical field, etc. [Explanation of symbols]

[0037] 100 Bubble Removal Cap 110 Housing 111 Connector part 112 Air bubble removal section 115 Bulkhead 116 Liquid passage 120 filters 121 First Layer 122 Second Layer 131 Space 132 Bubble separation space 133 Tip space 135 Step

Claims

1. a cylindrical housing having a connector portion at a base end thereof to which a syringe member is connected; a filter fixed to the housing closer to the tip than the connector portion, the filter having a plurality of pores and a water-absorbent polymer that swells when in contact with a liquid to close the pores; The filter has a first layer provided on the base end side and which is permeable to liquid, and a second layer provided on the tip end side, which contains more of the water-absorbing polymer than the first layer and prevents liquid from passing through.

2. 2. The bubble removal cap according to claim 1, wherein the filter is a porous sintered resin filter, and is press-fitted into the housing and compressed in the radial direction.

3. The housing allows the filter to be viewed, 2. The bubble elimination cap for a syringe of claim 1, wherein the first layer and the second layer are different colors.

Images