JP6097555B2 - Air venting chamber - Google Patents

Description

  The present invention relates to an air vent chamber provided in an extracorporeal circuit for circulating a fluid such as blood.

  An extracorporeal circuit such as a hemodialysis circuit is provided with a chamber for the purpose of preventing air bubbles from entering the fluid, removing bubbles in the fluid, removing foreign matter, and the like.

  For example, the extracorporeal circuit chamber described in Patent Document 1 is configured such that the liquid flows in the outer tangential direction of the chamber body together with the chamber body in which the liquid is stored and the liquid outlet provided at the lower end of the chamber body. By installing an inflow port equipped with a contrivance, the device is designed to keep the degree of stimulation given to the liquid low.

  In addition, an extracorporeal circuit chamber described in Patent Document 2 includes a chamber body that stores a liquid such as blood and an air layer formed above, a liquid inlet provided at the bottom of the chamber body, and a chamber And a liquid outlet provided at the bottom of the main body. Further, in this chamber, a protruding portion protruding above the liquid inflow port is formed, so that the inflowing liquid is swirled to suppress the spraying onto the liquid surface formed inside the chamber.

  Furthermore, the extracorporeal circuit chamber described in Patent Document 3 has a liquid inlet formed on the side of the chamber body and a liquid outlet formed below the chamber, respectively, as in Patent Document 1. A protrusion is formed so as to cross the opposite side of the outlet, and a device is devised to divide the liquid flow in the vertical direction to increase the efficiency of removing bubbles contained in the liquid.

Japanese Patent No. 3938557 Japanese Patent No. 2980647 US Pat. No. 5,591,251

  However, in conventional chambers, such as blood that generates blood clots by controlling the flow of liquids such as blood in order to efficiently remove bubbles, and being stimulated or staying outside the body for a long time. There is no structure that realizes both measures against liquids.

  In particular, the occurrence of thrombus in the blood circuit during hemodialysis significantly impairs the QOL of the dialysis patient, such as interruption of dialysis due to circuit replacement and the risk of embolism. For example, representative methods for suppressing thrombus formation include administration of anticoagulants (heparin, argatroban, etc.) and improvement of medical materials (heparin coating, etc.). However, administration of heparin increases bleeding tendency and has serious side effects, such as causing heparin-induced thrombocytopenia (HIT) due to the appearance of heparin-dependent autoantibodies. If possible, it is desirable to reduce the dose as much as possible.

  In addition, the dialysis circuit is required to be disposable from the viewpoint of avoiding infection risk, and since it is frequently used, it is practically difficult to apply expensive medical materials such as the material itself exhibiting anticoagulation properties. There is a present situation.

  On the other hand, it is presumed that the site of frequent thrombosis in the dialysis circuit is a chamber provided for air bubble removal, foreign matter removal, which may cause air contact, high shear flow, and stagnant portions. The improvement of the antithrombogenicity in this chamber apparatus may improve the antithrombogenicity of the entire dialysis circuit.

  Conventionally, in an upper inflow type chamber that has been generally used, a free jet at the inlet directly flows into the outlet, and a gentle vertical vortex and a stagnation region induced by the flow are formed. Similarly, in the side inflow type that has been conventionally used, a flow from the high-pressure portion facing the inlet to the outlet occurs, and the streamline is separated in the middle (specifically, the downward flow along the wall surface is A phenomenon in which the energy is lost and the wall is separated (separated), the flow in the vicinity of the wall below the separation point flows backward, and a vortex is generated in the separation streamline. At the same time, a gentle vertical vortex is formed on the opposite side of the stagnation region. The stagnation formed inside these chambers becomes a thrombus formation region, and its presence is not preferable.

  For example, in the spiral type shown in Patent Document 1, a strong transverse vortex (forced vortex) generated by a free jet at the inlet continues to the bottom of the chamber. Since this vortex is a forced vortex, a staying region (a region where the liquid flow is duller than other portions and staying, the same applies hereinafter) is generated in the center, and this is also a hotbed for thrombus formation and is not a preferable form.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an air venting chamber that can achieve both prevention of the generation of aggregates such as thrombus and air venting.

  In order to solve the above problems, in the present invention, as a bubble removal chamber of the extracorporeal circulation circuit, the high pressure at the stagnation point is dispersed in the inflow-facing portion of the side inflow type bubble removal chamber, which is a conventional technique, and a horizontal vortex is generated. Provided is a structure that suppresses thrombus generation by a rectifying effect and a stirring effect generated by providing a projection having a shape to be generated.

  In order to realize the structure as described above, the present inventor considered that the residence area that causes thrombus formation is small, and that the side inflow that is considered not to generate a strong shearing flow that activates platelets other than the high-pressure part facing the inlet is not generated. As a result of repeated investigations focusing on the thrombus suppression effect of the mold chamber, high antithrombogenicity has been achieved by installing a protrusion with a rectifying effect on the face of the inflow port that is the site of frequent thrombus formation in the chamber It came to obtain the knowledge to do.

  In a conventional side inlet chamber, a high pressure is generated at the stagnation point generated at the opposite side of the inlet, and a strong downward flow toward the low pressure part is generated along the side surface due to an increase in dynamic pressure due to an increase in the flow velocity at the outlet. Arises. Furthermore, tumble flow (longitudinal vortex) is generated by being induced by this flow. On the other hand, based on the knowledge of the present inventor, by installing a convex cone (protruding part) in a shape that disperses the high-pressure part to the left and right at the inlet facing, and dispersing the high-pressure part at the inlet facing around the cone It becomes possible to generate a pair of swirl flows (lateral vortices). Due to this pair of lateral vortices, the entire flow gently descends in the downstream direction. According to this structure, the stagnation and shear flow at the inlet facing the thrombus occurrence site are suppressed, and the stay region in the chamber disappears.

The present invention based on various studies and findings as described above is an air vent chamber used in an extracorporeal circulation blood circuit,
A substantially cylindrical chamber body;
An access section for venting air;
An inlet for introducing a liquid such as blood into the chamber body, the inlet being connected to the chamber body at an angle facing at least a part of the inner wall of the chamber body;
An outlet for discharging liquid such as blood from the chamber body;
A raised portion that is formed on the inner wall of the chamber body that faces the inflow port and that protrudes toward the inflow port;
With
The raised portion is located on the front or lower side in the facing direction of the inflow port, and a jet of blood ejected from the inflow port hits the raised portion.

  In the air bleeding chamber according to the present invention, it is preferable to suppress blood coagulation by preventing the bubble from being entrained due to the generation of a high pressure gradient and a stagnant region in the chamber body and the rising of the liquid level by the raised portion.

Further, in the air bleed chamber according to the present invention, the chamber body has an elongated shape having a long axis along the vertical direction and a short axis along the horizontal direction in the use state of the air bleed chamber,
By branching the jet in the minor axis direction, the conversion from the dynamic pressure of the jet to the static pressure in the low flow velocity region generated at the facing portion is reduced, and an increase in static pressure in the low flow velocity region is prevented. The raised portion reduces the flow velocity in the vicinity of the wall surface of the inner wall from the facing portion to the outlet, and suppresses the separation flow in the major axis direction.

  Further, in the air bleeding chamber according to the present invention, the bulging portion is a liquid flow generated at the facing portion by branching the jet in the minor axis direction in a region including the jet diameter at the center of the chamber body. It is characterized by reducing the pressure in the stagnation region.

  Furthermore, in the air venting chamber according to the present invention, the raised portion is a lateral vortex induced by the jet by fixing the stagnation point of the jet to the tip in the region including the jet diameter at the center of the chamber body. It is characterized by stabilizing the center position.

  Further, in the air venting chamber according to the present invention, the bulging portion is adapted to prevent disturbance in the major axis direction induced from the jet by the bulging portion in a region including a jet diameter from the inlet at the center of the chamber body. It is characterized by being smoothly molded to prevent it.

  Furthermore, the air bleeding chamber according to the present invention is characterized in that the raised portion and the inner wall surface of the chamber body are formed smoothly. Further, in this air vent chamber, when the liquid flow stagnation region in the vicinity of the wall surface of the inner wall is small enough not to affect the blood, the surface smoothly protrudes toward the liquid stagnation region. The protrusion to be attached may be attached.

  Furthermore, in the air bleeding chamber according to the present invention, it is preferable that the smoothly molded portion has a surface-to-surface connection portion formed by continuous curvature.

  Further, in the air vent chamber according to the present invention, the major axis of the bottom surface of the raised part is equal to or larger than the major axis of the jet when the jet reaches the raised part, and is larger than that of the raised part. The ratio (H / D) of the height (H) from the bottom surface portion to the apex portion and the major axis (D) of the bottom surface portion of the protuberance portion is in the range of 1 to 2, and the apex portion of the protuberance portion is the A flat portion having a diameter equal to or smaller than 1/10 of the major axis (D) of the bottom surface portion is provided.

  Furthermore, in the air bleed chamber according to the present invention, the bottom surface of the raised portion has a relationship of W ≧ Z between the horizontal axis length (W) and the vertical axis length (Z) when the air bleed chamber is used. It is characterized by its shape.

  Further, in the air venting chamber according to the present invention, the raised portion is below the liquid level of the liquid, and when the raised portion and the liquid level come close to each other, the rising of the liquid level is suppressed, and bubbles that cause thrombus formation are suppressed. It is characterized by suppressing entrainment.

  Moreover, the air bleeding chamber according to the present invention is characterized in that an inlet for injecting an anticoagulant into the chamber body is formed in the raised portion.

  Here, a study example based on linear theory is shown below for a cone-shaped ridge that disperses the pressure in the region facing the inlet (see FIG. 3).

Assuming that the collision jet with the cross-sectional area S ₀ is a uniform flow by an ideal fluid, the projected area of the cone is S ₁ , the collision angle on one side of the cone is θ, and the force that the jet flow tube expanded by the cone collides with the wall surface Is Fx, and the force that the cone receives in the tangential direction of the collision wall due to the mass exclusion effect of the cone is Fy. Assuming that the average pressure distribution around the cone is uniform when the pressure mitigated by the presence of the cone and the pressure generated by the jet colliding with the wall are equal,
Therefore,
Also, assuming that the law of conservation of momentum holds, assuming that the cone wall velocity is V, the fluid density is ρ, and the jet flow is Q.
Therefore,

When the cone shape is conical, the fluid is an ideal fluid, and a two-dimensional flow field is used, the pressure distribution in the cone peripheral region is flattened when the one-side angle of the cone tip satisfies the above equation. In the above formula
Then,
Therefore, if the cross-sectional area of the jet and the projected area of the cone are equal,
Cone height: Diameter = 1: 1
It is considered that the highest pressure dispersion effect can be obtained.

  Since the actual flow field is a three-dimensional, viscous flow field, the jet cross-sectional area decreases due to the contraction effect and diffuses due to turbulent transition, so it is necessary to correct the effective cross-sectional area based on the positional relationship between the inlet and cone. There is. In addition, it is necessary to correct the pressures Fx and Fy in consideration of energy loss due to cone wall frictional force or vortex generation.

  According to the present invention, it is possible to achieve both prevention of formation of aggregates such as thrombus and air bleeding.

It is (A) side view and (B) rear view which show an example of the conventional air bleeding apparatus. It is the (A) side view and (B) back view which show the air bleeding chamber which concerns on this invention. It is a figure for demonstrating the symbols of Formula 1-Formula 7 in the example examined by linear theory. It is sectional drawing in the IV-IV line of the air bleeding chamber shown in FIG. It is a figure which shows the calculation lattice of the air bleeding chamber shown in FIG. (A) is a figure which shows the liquid flow velocity distribution in the conventional air bleed chamber shown in FIG. 1, (B) is the liquid flow velocity distribution at the time of making a liquid flow in into the air bleed chamber which concerns on this invention shown in FIG. FIG. It is a figure which shows the steady streamline distribution at the time of changing a diameter in 3 mm increments between diameter φ = 0-12mm of cones. It is a figure which shows the comparison of the pressure distribution of the cone circumference | surroundings in the diameters φ = 3mm and φ = 6mm of a cone. It is a figure which shows the apparatus used for the visualization method of the clot formation process. It is a graph which shows the result of having investigated the difference in time taken to solidify with the presence or absence of a cone. It is a figure which shows the air bleeding chamber which concerns on 2nd Embodiment. It is sectional drawing in the XII-XII line | wire of the air bleeding chamber shown in FIG. It is a figure which shows the mode of the liquid flow at the time of flowing a liquid into the air bleeding chamber of FIG. It is a figure which shows the flow direction of the jet flow which flowed into the side surface of a cone, (A) shows the horizontal direction axial length (major axis) W = 6mm of the bottom face part of a cone, (B) shows the case where W = 9mm. It is a figure which shows the comparison of the pressure distribution of the bottom face part vicinity when (A) it has a circular bottom face part, and (B) it has an elliptical bottom face part. It is a figure which shows the result visualized by the suspension method using the polystyrene particle | grains as a tracer, and the laser light sheet method with the side view of the air bleed chamber of (A), (B) is the case where a cone is a cone, (C) is When there is no cone, (D) is a case where the cone is an elliptical cone. It is a figure of the air bleeding chamber which concerns on Example 4. FIG. It is a figure which shows the comparison of the result of having calculated the pressure distribution of the just upper cross section of the inflow port of FIG. 17, (A) is D = 0mm and H = 0mm, (B) is D = 3mm, H = 4. This is a case of 2 mm. It is a figure which shows the outline of the closed circuit used for the experiment which concerns on Example 4. FIG. It is a figure (flow rate 200mL / min) which shows the wave front at the time of no cone. It is a figure (flow rate 400mL / min) which shows the wave front at the time of no cone. It is a figure (flow rate 200mL / min) which shows the wave front at the time of cone presence. It is a figure (flow rate 400mL / min) which shows the wave front at the time of cone.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or equivalent elements will be denoted by the same reference numerals, and redundant description will be omitted. If necessary, an XYZ coordinate system in which the Z axis is the vertical axis and the XY plane is the horizontal plane is set, and X, Y, and Z may be used for convenience. In addition, with the Z direction facing upward, words including the concepts of “upper” and “lower” may be used in the description.

[First Embodiment]
A first embodiment of the present invention will be described. FIG. 1 is a view showing a configuration of a conventionally used air vent chamber. FIG. 2 is a view showing an air bleeding chamber according to the present invention, but is provided with a raised portion 15 that is not seen in FIG.

  As an example, the main body 13 (hereinafter referred to as “chamber main body”) of the air vent chamber 10 has an elongated shape having a substantially cylindrical shape and a dome-shaped housing at both ends (see FIG. 1 and the like). The long axis of the chamber body 13 which is an elongated shape is an axis along the Z axis (vertical axis) when the air bleeding chamber 10 is used, and the short axis perpendicular thereto is the X axis and the Y axis (horizontal axis). It is an axis along each. The chamber body 13 is provided with a liquid inlet 11 and an outlet 12, respectively. In addition, a raised portion 15 is provided on the inner wall 14 of the chamber body 13.

  The inflow port 11 is a liquid circulation port for introducing a liquid such as blood into the chamber body 13. In the present embodiment, the inlet 11 is at an angle facing at least a part of the inner wall 14 of the chamber body 13 (in other words, an angle at which the liquid that has passed through the inlet 11 flows toward one of the inner walls 14). ) And connected to the chamber body 13 (see FIG. 2 etc.). Further, the inflow port 11 flows in such a manner that the jet flow from the inflow port 11 is parallel to the liquid level in the chamber body 13 (the liquid level of the internal liquid in the air bleed chamber 10 in use). Is provided.

  The outflow port 12 is a liquid circulation port for discharging a liquid such as blood from the chamber body 13. The outlet 12 of the present embodiment is provided at the bottom of the chamber body 13 (see FIG. 2 and the like).

  The raised portion 15 is formed in a conical shape, for example, so as to rise toward the inflow port 11 at a portion facing the inflow port 11 in the inner wall 14 of the chamber body 13 (see FIG. 2 and the like). In the present embodiment, the entire raised portion (cone) 15 of the raised portion (hereinafter also referred to as a cone) 15 is positioned below the liquid level (liquid level) of the liquid in the direction in which the inflow port 11 faces. Are arranged as follows. The raised portion 15 may be formed by bending and deforming only the portion while maintaining the thickness of the chamber body 13 as a whole, or may be formed by changing the thickness of only the portion. (See FIG. 4).

  The raised portion 15 formed as described above prevents blood bubbles from coagulating and blood clots caused by the blood coagulation by preventing a high pressure gradient in the chamber body 13 and the generation of a stagnant region and entrainment of bubbles due to the rising of the liquid level. Suppresses the occurrence of

  In addition, it is also preferable that an inlet for injecting an anticoagulant such as continuous heparin into the chamber body 13 is formed in the raised portion 15. By using such an injection port, it is possible to further improve the thrombus generation suppressing effect in the chamber body 13.

  Further, in the air vent chamber 10 as described above, it is preferable that the raised portion 15 and the inner wall 14 of the chamber body 13 are formed smoothly. The raised portion 15 in the air bleed chamber 10 of the present embodiment is guided from the jet by the raised portion 15 in a region including the diameter of the jet from the central inlet 11 of the chamber body 13 (a region including the entire cross section of the jet). Smoothly shaped to prevent long axis disturbance. There are no irregularities or suddenly changing parts between the raised portions 15 and the inner wall 14 of the chamber body 13, and the two are smoothly connected to each other, resulting in a connection between the raised portions 15 and the chamber body 13 that cause thrombus formation. Itching can be suppressed. Further, in this air vent chamber 10, when the liquid flow stagnation region in the vicinity of the wall surface of the inner wall 14 is small enough not to affect blood, it projects toward the liquid stagnation region on the smoothly molded surface. The protrusion to be attached may be attached.

  The access unit 16 is a part for extracting air. In this embodiment, the tube for air bleeding installed in the top part of the chamber main body 13 is used as the access part 16 (refer FIG. 2).

  In the air vent chamber 10 as described above, a liquid such as blood flows as a jet from the inlet 11 into the chamber body 13. The jet branches in the minor axis direction (the horizontal direction in the use state of the air bleeding chamber 10) in the region including the jet at the center of the chamber body 13. At this time, the conversion from the dynamic pressure of the jet flow to the static pressure in the low flow velocity region generated at the facing portion (the portion facing the inlet 11) is reduced, and a significant increase in static pressure in the low flow velocity region is suppressed. Further, the raised portion 15 reduces the flow velocity in the jet direction in the vicinity of the wall surface of the inner wall 14 from the facing portion to the outlet 12, and suppresses the separation flow in the major axis direction of the liquid. In this way, the raised portion 15 acts on the jet of liquid, and the jet flow is branched in the short axis direction in the region including the jet diameter at the center of the chamber body 13, and the pressure of the liquid stagnation region generated at the facing portion Decrease. Further, the raised portion 15 stabilizes the center position of the horizontal vortex induced by the jet by fixing the stagnation point of the liquid jet at the tip in the region including the jet diameter at the center of the chamber body 13. In general, a decrease in the flow velocity in the vicinity of the wall surface from the facing portion of the inlet 11 to the outlet 12 may adversely affect blood such as thrombus formation or hemolysis, but this embodiment According to the air vent chamber 10 which concerns, such an influence can be suppressed.

  Further description of fixing the stagnation point of the above-described liquid jet to the tip is as follows. That is, in an object placed in a fluid, a point where the relative flow velocity with respect to the object becomes 0 occurs somewhere on the object surface. This part is called a grudge point. Since the streamline branches around the stagnation point, if the position of the stagnation point fluctuates, it greatly affects the stability of the subsequent stream. This can be considered that the instability of the wake affects the position of the stagnation point, but it is known that there is an effect of stabilizing the flow by fixing the stagnation point (or separation point) by devising the shape. It has been.

[Example 1]
Since simulation and experiment were performed in the air bleeding chamber 10 formed as in the first embodiment described above, the result will be described as Example 1.

  Using the fluid analysis software Phoenics ver.3.5.1 (manufactured by CHAM), the difference in pressure distribution across the inlet 11 depending on the presence or absence of the cone 15 and the difference in the flow field (area where fluid such as blood circulates) due to the cone diameter Compared. The Large Eddy Simulation model was applied as the calculation model. FIG. 2 shows the shape of the air vent chamber 10 and FIG. 5 shows an example of a calculation grid. The calculation grid was a non-uniformly spaced orthogonal grid (staggered mesh), and the height x width x depth = 100 x 60 x 150. The viscosity was 3 mPa · s (3 cP), the flow rate was 200 ml / min, and a steady flow velocity value satisfying the continuous flow rate condition was given to both the inflow port 11 and the outflow port 12 as a boundary condition.

  FIG. 6 shows a comparison of the pressure distribution of the inlet facing the presence of the cone 15 when the ratio of the diameter and height of the cone 15 is 1 and the diameter is 6 mm (twice the diameter of the inlet 11). By installing the cone 15, the pressure in the vicinity of the stagnation point facing the inlet is significantly reduced.

  FIG. 7 shows steady streamline distributions in the case of five diameters of diameter φ = 0 mm, 3 mm, 6 mm, 9 mm, and 12 mm. Here, the horizontal vortex generated in the vicinity of the inflow port 11 is stored to the downstream, so that the streamline from the cone 15 toward the outflow port 12 is separated from the wall surface (specifically, the downward flow along the wall surface). This is a phenomenon that loses its energy and peels (separates) from the wall surface.The flow in the vicinity of the wall surface below the separation point flows backward and vortices are generated in the separation streamline), and a high stirring effect is achieved. It was confirmed that there was. It was also confirmed that the rectifying effect of the cone 15 having a diameter two to three times (φ = 6 mm, 9 mm) of the inlet diameter (φ = 3 mm) was the highest.

  FIG. 8 shows a comparison of pressure distribution around a cone having a diameter φ = 3 mm and φ = 6 mm. When the inner diameter of the cone 15 is equal to the inner diameter of the inlet 11 (φ = 3 mm), a pressure field with a high stagnation point (area where the pressure acts) is stored around the cone, but the inner diameter of the cone 15 is the inlet 11. Is larger than the inner diameter (φ = 6 mm), the pressure field is distributed at the cone apex and the periphery. It can be inferred that this pressure dispersion effect has a great influence on the flow field.

  In order to examine the effect of the air bleeding chamber 10 according to the present invention on the antithrombogenicity, a method for visualizing the thrombus generation process devised by the present inventors was applied (see FIG. 9). Here, fresh frozen plasma is diluted 2-fold with physiological saline and filled in a closed circuit including the air venting chamber 10, cooled to 18.5 ° C., and ACT (activated clotting time) = 170 seconds at 37 ° C. Inhibition of coagulation was released by injecting cartilol so prepared. In the air bleed chamber 10 with a cone according to the present embodiment and the air bleed chamber 10 having the same external shape and the cone 15 not formed, the temperature was gradually recovered to 37 ° C., and the coagulation start times were compared. The slower the coagulation start time, the higher the coagulation suppression effect.

  In the air vent chamber 10 with a cone (φ = 6 mm), solidification started in 1280 seconds (35.8 ° C.) from the measurement start time (18.5 ° C.). In the absence of cone 15, the time to start of solidification was 990 seconds (34.6 ° C.). The cone 15 with Φ = 3 mm started to solidify in 930 seconds (34.9 ° C.). In the air bleed chamber 10 with a cone 15 of φ = 6 mm, since the coagulation start time has been remarkably extended, the addition of the corn 15 according to the present invention to the conventional air bleed chamber 10 has an effect of suppressing blood coagulation. Was confirmed. (See Figure 10)

[Second Embodiment]
Subsequently, a second embodiment of the present invention will be described. FIG. 11 is a view showing an air bleeding chamber 10 according to the second embodiment. 12 is a cross-sectional view taken along line XII-XII of the air vent chamber 10 shown in FIG.

  When the bottom surface portion 15b of the raised portion 15 in the air vent chamber 10 is substantially circular, the average diameter of the bottom surface portion 15b is approximately equal to or equal to the diameter of the jet flow when the liquid jet reaches the raised portion 15. Larger is preferred. Further, the ratio (H / D) of the height (H) from the bottom surface portion 15b of the raised portion 15 to the pointed portion 15a and the average diameter (D) of the bottom surface portion 15b of the raised portion 15 is in the range of 1-2. Preferably there is. Further, the pointed portion 15a of the raised portion 15 includes a flat portion having a diameter equal to or less than 1/10 of the average diameter (D) of the bottom surface portion 15b, which fixes the position of the stagnation point at the cone tip portion, It is preferable for suppressing the fluctuation. Hereinafter, as Example 2, the height H of the raised portion 15 is set to H1 with respect to the average diameter of the bottom surface portion 15b of the raised portion 15 (the average of the major axis and the minor axis when the shape of the bottom surface is an ellipse). , H2, and H3, and changes in the liquid flow and pressure distribution in the chamber body 13 are obtained by simulation in the same manner as in the first embodiment.

[Example 2]
Longitudinal direction in which the height H is changed in increments of 3 mm between H = 3 mm and 12 mm and the liquid rising direction is positive with respect to the cone diameter D = 6 mm under the same calculation conditions as in the first embodiment. The effect of preserving the transverse vortex was examined by the contour surface where the flow velocity was zero. By this lower limit position of the contour surface, it is possible to confirm the degree of the effect that the horizontal vortex is preserved and the upward flow at the center of the vortex is maintained. That is, as the lower limit of the contour surface exists on the downstream side, the stirring effect of the horizontal vortex is better preserved.

  The results are shown in FIG. It was revealed that the constant velocity surface was most distributed downward when D = 6 mm, H = 6 mm, that is, when the cone diameter to height ratio was 1: 1. At this time, a flow field (lateral swirl flow field) is formed with the contour surface outer portion facing downward and the center portion facing upward, and the formation of this stable flow field prevents separation and suppresses blood coagulation. In this calculation result, this effect was confirmed from D: H up to 1: 0.5 to 1: 2, and it was also confirmed that it disappeared at higher D: H (1: 3).

[Third Embodiment]
In the present invention, the jet flow that flows into the side surface of the cone 15 becomes a swirl flow that depends on the shape (cylindrical shape) of the chamber body 13, and the momentum loss increases the pressure on the side surface (conical surface) of the cone 15. Therefore, the gradient of the side surface of the cone 15 is made smaller as shown in FIG. 14B than in FIG. 14A (specifically, the gradient at the inflow and the gradient at the outflow are set to be equal). Thus, a reduction effect of momentum loss is expected. Further, when the horizontal axis length (major axis) of the bottom surface portion 15b of the cone 15 is W and the vertical axis length (minor axis) is Z, it is preferable that W ≧ Z. A horizontally flat shape that satisfies W ≧ Z increases the effect of dispersing the pressure generated by the jet flow to the left and right, so that a horizontal vortex is easily generated.

[Example 3]
FIG. 15 shows a comparison of pressure distributions in the vicinity of the bottom surface portion when the elliptical bottom surface portion 15b having a diameter of 6 mm and a height of 6 mm with a lateral width of 9 mm is provided under the same calculation conditions as in the first embodiment. Since the region where the pressure increases becomes narrower in the elliptical cone, the pressure dispersion effect on the side surface of the cone 15 having a horizontally long cross section was confirmed.

  Further, in order to experimentally evaluate the influence of the lateral width of the cone 15 on the vortex formation, the flow field in the cross section immediately below the inlet 11 was visualized by a suspension method using polystyrene particles as a tracer and a laser light sheet method. . FIG. 16 shows an outline of measurement positions and observation results. A horizontal vortex occurs around the stagnation point regardless of the presence or absence of the cone 15. However, when there is no cone, the vortex center fluctuates greatly, but when there is a cone cone, the fluctuation of the vortex center is small. It was confirmed that a vortex was formed. The horizontal vortex in the air vent chamber 10 is formed as a pair of vortices swirling in opposite directions, but the vortex center position fluctuates periodically due to mutual interference, and the vortex structure tends to disappear. From the result of Example 3, it is suggested that the installation of the cone 15 facing the inlet 11 may contribute to enhancing the dynamic stability of the vortex structure. In addition, this effect is presumed to be brought about by fixing the position of the high-pressure portion that becomes the stagnation point at the tip of the cone, and optimization of the cone width is considered to enhance the effect.

[Fourth Embodiment]
When the liquid surface position approaches the inflow port 11, the pressure generated in the stagnation region facing the inflow port 11 raises the water surface (forming), and the blood coagulation factor may be activated by the entrainment of bubbles to generate a thrombus. is there. With respect to such an event, the air vent chamber 10 according to the present invention is expected to have an effect of suppressing forming based on the pressure dispersion and rectification effect by the cone 15.

[Example 4]
In order to confirm this effect, FIG. 18 shows a comparison of the results of calculating the pressure distribution of the section directly above the inlet 11 with the upper part of the inlet 11 shown in FIG. 17 as the upper end of the calculation region. As a result, it was confirmed that the cone 15 has an effect of alleviating the rise in pressure on the liquid surface.

  In order to verify this effect experimentally, in the closed circuit shown in FIG. 19, condensed milk as a pigment was mixed, and a glycerin aqueous solution adjusted to a concentration of 3 mPa · s (3 cP) having a viscosity similar to that of blood was flowed at 200 ml. And the wave front was visualized by a laser light sheet, and the influence of the presence or absence of the cone 15 on the forming was examined.

  FIGS. 20 and 21 show the wavefront visualization results and the maximum wave height when there is no cone and FIGS. 22 and 23 show the case with a cone (diameter 6 mm). As a result, the wave height was about 14 mm when the cone 15 was not present at a flow rate of 400 mL / min, whereas the wave height was significantly reduced to about 5 mm when the cone 15 was installed. From this result, it is clear that the air venting chamber 10 according to the present invention is expected to have an effect of preventing wavefront heightening (foaming) on the opposite side of the inlet 11 based on the pressure dispersion effect of the cone 15. became.

  The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the scope of the present invention. For example, in the above-described embodiment, the cone 15 is illustrated as a specific example of the raised portion. However, this is only a preferable example, and a cone having an elliptical bottom surface portion 15b or a vertex position at the center position of the bottom surface portion 15b. It may be an asymmetric cone that does not match. Or it may be a case where it is not a cone in a strict sense, such as unevenness in the bottom part 15b or the side. In short, a portion of the inner wall 14 of the chamber body 13 that faces the inlet 11 is formed so as to rise toward the inlet 11, and a high pressure gradient and a residence region are generated in the chamber body 13. The specific shape of the raised portion 15 is not particularly limited as long as the raised portion 15 suppresses blood coagulation (thrombus) by preventing entrainment of bubbles due to the rise of the liquid level.

  The present invention is useful when applied to a chamber for venting air used in an extracorporeal circulation blood circuit.

DESCRIPTION OF SYMBOLS 10 ... Air venting chamber 11 ... Inlet 12 ... Outlet 13 ... Chamber main body 14 ... Inner wall 15 ... Cone (bump part)
15a ... apex 15b ... bottom 16 ... access part

Claims (13)

An air vent chamber used in an extracorporeal blood circuit,
A substantially cylindrical chamber body;
An access section for venting air;
An inlet for introducing a liquid such as blood into the chamber body, the inlet being connected to the chamber body at an angle facing at least a part of the inner wall of the chamber body;
An outlet for discharging liquid such as blood from the chamber body;
A raised portion that is formed on the inner wall of the chamber body that faces the inflow port and that protrudes toward the inflow port;
With
The chamber body is an elongated shape having a long axis along the vertical direction and a short axis along the horizontal direction in the use state of the air bleeding chamber,
Wherein the raised portion is located opposite or lower side of the inlet of the facing direction, Ri or jet of blood ejected from the inflow port Animal Crossing the ridge diverts the jet in the minor axis direction <br An air vent chamber characterized by the above.   2. The air bleeding according to claim 1, wherein the bulging portion suppresses blood coagulation by preventing generation of a high pressure gradient and a staying region in the chamber body and bubble entrainment due to a liquid surface bulge. Chamber. Reduces the conversion of the dynamic pressure of the previous SL jet to a static pressure of the low flow rate region generated in the facing portion, thereby preventing an increase in static pressure in the low flow rate region, the raised portion, the flow from the facing portion The air bleeding chamber according to claim 1 or 2, wherein a flow velocity in the vicinity of the wall surface of the inner wall reaching the outlet is decreased to suppress the separation flow in the long axis direction.   In the region including the jet diameter at the center of the chamber body, the bulging portion diminishes the jet in the minor axis direction, thereby reducing the pressure of the liquid stagnation region generated in the facing portion. The air bleeding chamber according to any one of claims 1 to 3.   In the region including the jet diameter at the center of the chamber main body, the raised portion fixes the stagnation point of the jet to the tip portion, thereby stabilizing the position of the horizontal vortex center induced by the jet. The air bleeding chamber according to any one of claims 1 to 4.   The raised portion is smoothly molded in a region including the jet diameter from the inlet at the center of the chamber body so as to prevent disturbance in the major axis direction induced from the jet by the raised portion. 6. A venting chamber according to any one of the preceding claims, characterized in that it is characterized in that   The air bleeding chamber according to any one of claims 1 to 6, wherein the raised portion and an inner wall surface of the chamber main body are formed smoothly.   When the liquid flow stagnation region in the vicinity of the wall surface of the inner wall is small enough not to affect blood, a protrusion that protrudes toward the liquid stagnation region is attached to the smoothly molded surface. The air bleeding chamber according to claim 7. The portion where the raised portion and the inner wall surface of the chamber body are smoothly formed have a surface-to-surface connection portion formed by a continuous curvature, according to any one of claims 6 to 8. The air bleeding chamber according to Item.   The major axis of the bottom surface of the raised part is equal to or larger than the major axis of the jet when the jet reaches the raised part, and the height from the bottom part of the raised part to the tip ( H) and the ratio (H / D) of the major part (D) of the bottom part of the raised part is in the range of 1 to 2, and the tip part of the raised part is 1 / of the major axis (D) of the bottom part. The air vent chamber according to any one of claims 1 to 9, further comprising a flat portion having a diameter of 10 or less.   The bottom surface of the raised portion has a shape in which the relationship between the horizontal axial length (W) and the vertical axial length (Z) is W ≧ Z when the air bleeding chamber is used. Item 11. The air bleeding chamber according to Item 10.   The bulge portion is below the liquid level of the liquid, and when the bulge portion and the liquid surface approach each other, the bulge of the liquid surface is suppressed, and entrainment of bubbles that cause thrombus formation is suppressed. The air bleeding chamber as described in any one of 1-9.   The air bleeding chamber according to any one of claims 1 to 12, wherein an inlet for injecting an anticoagulant into the chamber body is formed in the raised portion.