Blood drainage cannula

Abstract

To provide a cannula for blood removal that is not difficult to be inserted into a blood vessel even when a diameter of a blood vessel insertion part is increased.SOLUTION: A cannula for blood removal 10 includes: an external cylinder 11; and a blood vessel insertion part 12 stored in the external cylinder 11 while the diameter thereof is compressed. Pulling out the external cylinder 11 after insertion into a blood vessel allows the blood vessel insertion part 12 to extend the diameter thereof in the blood vessel.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a cannula for blood drainage.

Background Art

[0002] In an extracorporeal membrane oxygenation (ECMO) device, percutaneous cardiopulmonary support (PCPS) device, or the like equipped with a blood pump, a cannula for blood drainage is used (see Non-Patent Document 1).

[0003] For example, when using an extracorporeal membrane oxygenation device or the like, as the cannula for blood drainage, a cannula with an outer diameter equal to or slightly smaller than the inner diameter of the blood vessel at the insertion site is selected. The blood pump drains (suctions) blood through this cannula and expels (pumps) it to the artificial lung. A cannula for blood drainage having an outer diameter larger than the inner diameter of the blood vessel at the insertion site is not used.

Prior Art Documents

Non-Patent Documents

[0004] [[ID=,26]]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The small diameter of the blood withdrawal cannula presents the following challenges: (1) The diameter of the blood pump's suction port cannot be increased, resulting in low flow rate and potentially insufficient blood circulation. Also, (2) the increased suction flow rate (higher negative pressure) can lead to hemolysis. On the other hand, increasing the diameter of the blood withdrawal cannula makes it difficult to insert into the blood vessel.

[0006] The present invention has been made in consideration of the above points. The object of the present invention is to provide a blood withdrawal cannula that does not become difficult to insert into a blood vessel even when the diameter of the vascular insertion portion is increased. [Means for solving the problem]

[0007] A blood drainage cannula according to a first aspect of the present invention is Outer cylinder and The vascular insertion portion, which is housed within the outer cylinder with its diameter compressed, Equipped with, After insertion into the blood vessel, the outer sheath is withdrawn, causing the vascular insertion portion to expand in diameter within the blood vessel.

[0008] In this configuration, the vascular insertion portion is housed within the outer sheath with its diameter compressed. Even if the diameter of the vascular insertion portion is increased, the diameter of the outer sheath remains unchanged, thus preventing difficulty in insertion into blood vessels. Therefore, it becomes possible to select a cannula with a larger diameter than conventional ones for blood withdrawal. This allows for (1) an increase in the diameter of the blood pump's suction port, improving suction performance and ensuring sufficient blood flow. It also reduces the likelihood of excessive negative pressure that could destroy blood cells, thus preventing hemolysis. Consequently, the blood circulation performance in cardiopulmonary bypass machines and the like improves, increasing the expectation of therapeutic efficacy, life support, and improved prognosis.

[0009] A blood-withdrawing cannula according to a second aspect of the present invention is a blood-withdrawing cannula according to a first aspect, In its natural state, the outer diameter of the vascular insertion site is larger than the inner diameter of the blood vessel to which it is inserted.

[0010] A blood-withdrawing cannula according to a third aspect of the present invention is a blood-withdrawing cannula according to a second aspect, The expansion of the vascular insertion portion within the blood vessel is stopped when at least a portion of the outer surface is concave inward due to the reaction force received from the inner surface of the blood vessel.

[0011] In this configuration, a flow path is formed between the inwardly recessed portion of the outer surface of the vascular insertion site and the inner surface of the blood vessel, thereby maintaining blood flow downstream from the insertion site (for example, to the lower limbs).

[0012] A blood drainage cannula according to a fourth aspect of the present invention is a blood drainage cannula according to a second aspect, The aforementioned vascular insertion portion expands in diameter within the blood vessel by pushing and widening the inner circumferential surface of the blood vessel until it becomes circular in cross-sectional view.

[0013] This configuration ensures that the blood flow circulating through the cardiopulmonary bypass machine is maximized. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a blood withdrawal cannula that does not become difficult to insert into a blood vessel even if the diameter of the vascular insertion portion is increased. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1 is a diagram showing a schematic configuration of an artificial cardiopulmonary bypass machine according to one embodiment. [Figure 2] Figure 2 is a side view of a blood drainage cannula according to one embodiment. [Figure 3] Figure 3 shows a cross-section of the blood-withdrawing cannula shown in Figure 2, cut along line AA. [Figure 4] Figure 4 is a side view of the blood withdrawal cannula before the vascular insertion portion is housed within the outer sheath. [Figure 5] Figure 5 shows a cross-section of the blood-withdrawing cannula shown in Figure 4, cut along the BB line. [Figure 6]FIG. 6 is a cross-sectional view showing an example of a state in which the blood vessel insertion portion has expanded in the blood vessel by pulling out the outer cylinder after insertion into the blood vessel. [Figure 7] FIG. 7 is a cross-sectional view showing another example of a state in which the blood vessel insertion portion has expanded in the blood vessel by pulling out the outer cylinder after insertion into the blood vessel.

Embodiments for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description and the drawings used in the following description, for parts that can be configured identically, the same reference numerals are used and duplicate descriptions are omitted.

[0017] FIG. 1 is a diagram showing a schematic configuration of a cardiopulmonary bypass device 1 according to an embodiment.

[0018] As shown in FIG. 1, the cardiopulmonary bypass device 1 has a blood drainage cannula 10, a blood pump 20, a membrane oxygenator 30, and a blood delivery cannula 40.

[0019] Among these, the tip of the blood drainage cannula 10 is inserted into the blood vessel (for example, the femoral vein) of the patient P, and the base end is connected to the suction port of the blood pump 20 via a blood delivery tube. The discharge port of the blood pump 20 is connected to the inlet of the membrane oxygenator 30 via a blood delivery tube. The outlet of the membrane oxygenator 30 is connected to the base end of the blood delivery cannula 40 via a blood delivery tube, and the tip of the blood delivery cannula 40 is inserted into the blood vessel (for example, the femoral artery) of the patient P.

[0020] When the blood pump 20 and the membrane oxygenator 30 are operated, the blood taken out from the blood vessel of the patient P through the blood drainage cannula 10 is sucked from the suction port of the blood pump 20 and expelled from the discharge port to the membrane oxygenator 30. The blood to which oxygen has been added in the membrane oxygenator 30 is returned to the blood vessel of the patient P through the blood delivery cannula 40. In this way, blood circulation is performed through the cardiopulmonary bypass device 1.

[0021] Next, the structure of the blood withdrawal cannula 10 will be described with reference to Figures 2 to 4. Figure 2 is a side view of the blood withdrawal cannula 10 with the vascular insertion portion 12 housed inside the outer sheath 11, and Figure 3 is a cross-section of the blood withdrawal cannula 10 shown in Figure 2, cut along line AA. Figure 4 is a side view of the blood withdrawal cannula before the vascular insertion portion 12 is housed inside the outer sheath 11, and Figure 5 is a cross-section of the blood withdrawal cannula shown in Figure 4, cut along line BB.

[0022] As shown in Figures 2 to 5, the blood withdrawal cannula 10 has a connection part 13 that is connected to a tube extending from the suction port of the blood pump 20, a vascular insertion part 12 that is inserted into a blood vessel, and an outer cylinder 11.

[0023] In its natural state, the outer diameter D0 of the vascular insertion portion 12 (see Figure 5) is larger than the inner diameter of the outer cylinder 11, and as shown in Figures 2 and 3, the vascular insertion portion 12 is housed within the outer cylinder 11 with its diameter compressed (for example, in a folded or flattened state). In this specification, "housed with its diameter compressed" means, referring to Figure 3, that when a circle R is drawn that touches the vascular insertion portion 12 housed within the outer cylinder 11 at at least three points, the diameter D1 of that circle R is smaller than the outer diameter D0 of the vascular insertion portion 12 in its natural state (see Figure 5). The material used for the vascular insertion portion 10 is a resin, metal, or both, which are elastic and biocompatible materials.

[0024] The outer tube 11 has a cylindrical shape overall, and its specific configuration is not particularly limited as long as it can maintain the vascular insertion portion 12 housed inside in a compressed state (for example, in a folded and flattened state as shown in Figure 3). For example, the outer surface may be mesh-shaped, or the overall shape may be coil-shaped. The material of the outer tube 11 can be any biocompatible material, such as resin.

[0025] When using the cardiopulmonary bypass machine 1, the vascular insertion portion 12 of the blood withdrawal cannula 10 is inserted into the patient P's blood vessel (for example, the femoral vein) while compressed in diameter and housed within the outer sheath 11, as shown in Figures 2 and 3. Here, since the vascular insertion portion 12 is compressed in diameter and housed within the outer sheath 11, even if the diameter of the vascular insertion portion 12 is increased, the diameter of the outer sheath 11 does not change, and therefore insertion into the blood vessel does not become more difficult. As a result, it becomes possible to select a cannula with a larger diameter than conventional ones for the blood withdrawal cannula 10.

[0026] After insertion into the blood vessel, the outer sheath 11 is withdrawn, and the elastic recovery force of the vascular insertion portion 12 causes the vascular insertion portion 12 to expand within the blood vessel (it expands as it tries to return from a folded, collapsed state to its original circular shape).

[0027] In its natural state, the outer diameter D0 (see Figure 5) of the vascular insertion portion 10 may be larger than the inner diameter of the target blood vessel V.

[0028] For example, the elastic recovery force of the vascular insertion portion 12 may be smaller than the reaction force received from the inner surface of the blood vessel V, and as shown in Figure 6, the expansion of the vascular insertion portion 11 within the blood vessel V may stop at a shape in which at least a part of the outer surface is concave inward due to the reaction force received from the inner surface of the blood vessel V. In this case, a flow path C is formed between the inwardly concave portion of the outer surface of the vascular insertion portion 12 and the inner surface of the blood vessel V, so that blood flow to blood vessels downstream of the insertion position of the vascular insertion portion 12 (for example, in the lower limbs) can be maintained.

[0029] Alternatively, the elastic recovery force of the vascular insertion portion 12 may be greater than the reaction force received from the inner surface of the blood vessel V, and as shown in Figure 7, the vascular insertion portion 12 may expand in diameter within the blood vessel V by pushing out the inner surface of the blood vessel V until it becomes circular in cross-section. In this case, although blood flow to the blood vessel downstream of the insertion point of the vascular insertion portion 12 (for example, the lower limb) is interrupted, the maximum blood flow circulating in the cardiopulmonary bypass machine 1 can be ensured.

[0030] According to this embodiment, the vascular insertion portion 12 of the blood withdrawal cannula 10 is housed within the outer cylinder 11 with its diameter compressed. Even if the diameter of the vascular insertion portion 12 is increased, the diameter of the outer cylinder 11 remains unchanged, making insertion into the patient P's blood vessels easier. Therefore, it becomes possible to select a cannula with a larger diameter than conventional ones for the blood withdrawal cannula 10. This allows for (1) an increase in the diameter of the suction port of the blood pump 20, improving suction performance and ensuring sufficient blood flow. It also reduces the likelihood of excessive negative pressure that could destroy blood cells, thus preventing hemolysis. Consequently, the blood circulation performance in the cardiopulmonary bypass machine 1, etc., is improved, increasing the expectation of therapeutic effects, life support, and improved prognosis.

[0031] Although embodiments and modifications of the present invention have been described above by example, the scope of the present invention is not limited thereto, and modifications and alterations can be made within the scope described in the claims depending on the purpose. For example, the blood vessel into which the blood withdrawal cannula is inserted is not limited to the femoral vein, but can also be used in other blood vessels, such as the subclavian artery. Furthermore, each embodiment and modification can be appropriately combined as long as the processing content is not contradictory. [Explanation of symbols]

[0032] 1 Heart-lung machine 10. Cannula for blood drainage 11 Outer cylinder 12 Vascular insertion site 13 Connection part 20 Blood pumps 30 Membrane oxygenator 40. Blood cannula C channel P patient V blood vessel

Claims

1. It is a cannula for blood drainage, Outer cylinder and The vascular insertion portion, which is housed within the outer cylinder with its diameter compressed, Equipped with, After insertion into the blood vessel, the outer sheath is withdrawn, causing the vascular insertion portion to expand in diameter within the blood vessel. A blood withdrawal cannula, wherein the expansion of the vascular insertion portion within the blood vessel is stopped by a reaction force received from the inner circumferential surface of the blood vessel, resulting in at least a portion of the outer circumferential surface being concave inward.

2. In its natural state, the outer diameter of the vascular insertion portion is larger than the inner diameter of the blood vessel to which it is inserted. A blood drainage cannula according to claim 1.

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