An indwelling needle

Abstract

The application provides a remaining needle, which comprises a needle head, a hose, a conversion shell connected with the other end of the hose and forming a conversion cavity in the conversion shell, a valve core arranged in the conversion cavity, the valve core comprising an inner cylinder layer and an outer cylinder layer, the inner cylinder layer forming a blood sampling cavity, the inner cylinder layer and the outer cylinder layer forming a transfusion cavity, the transfusion cavity being arranged apart from the blood sampling cavity, a first blood sampling communication port being formed on the front end wall of the inner cylinder layer in the axial direction, the outer cylinder layer being provided with a first transfusion communication port on one side and a second blood sampling communication port and a second transfusion communication port on the other side, the second blood sampling communication port being communicated with the blood sampling cavity through an interlayer channel, a first sealing ring being sleeved on the outer periphery of the rear part of the outer cylinder layer, a balance cavity being formed between the rear part of the outer cylinder layer and the inner wall of the conversion shell, and an elastic element being arranged in the conversion cavity, one end of the elastic element abutting against the valve core and the other end abutting against the conversion shell. The remaining needle provided by the application has a spaced blood sampling passage and a transfusion passage, and has high safety and convenience in use.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, specifically to an indwelling needle. Background Technology

[0002] Indwelling needles are commonly used medical devices in clinical intravenous infusion therapy. They involve inserting a soft needle into a patient's blood vessel through puncture, avoiding the pain caused by repeated punctures and facilitating clinical medication administration and emergency drug delivery. In clinical practice, venous puncture is particularly difficult and has a low success rate in children due to their smaller blood vessels, thicker subcutaneous fat, and poor cooperation. Repeated punctures not only cause significant pain and fear for the children but also increase parental anxiety and the workload for medical staff. Therefore, utilizing existing indwelling venous access for blood collection whenever possible is an urgent need for clinical medical staff.

[0003] Currently, in clinical practice, blood collection via indwelling needles typically requires multiple syringes and connector changes. The procedure generally involves first using the first syringe to draw fluid exceeding the indwelling pathway volume and discarding it. Then, a second syringe draws 5-10 ml of fluid and sets it aside. A third syringe is then used to draw the required blood sample. Finally, the previously drawn fluid is reinfused and the infusion set is connected for continued treatment. However, the current structure of indwelling needles means that some blood may remain in the flow channel after blood collection. If medical staff lack experience or the reinfusion and cleaning process is improper and fails to completely remove the residual blood, this residual blood can easily breed bacteria, leading to puncture site infection, bloodstream infection, and other safety hazards. It can also cause blockage of the flow channel, affecting the effectiveness of subsequent infusions.

[0004] Currently, there is no existing technology that can achieve independent flow channels for blood collection and infusion, and can automatically switch modes and block channels. This cannot fundamentally solve the above-mentioned technical pain points. Therefore, developing an indwelling needle that can separate blood collection and infusion channels, automatically switch channels, and automatically block residual blood has become an urgent need in the field of clinical medical devices. Summary of the Invention

[0005] Therefore, in order to overcome the problems of residual blood in the connector and high risk of infection after blood collection by indwelling needles in the prior art, the present invention provides a valve core component with spaced blood collection chamber and infusion chamber, and can automatically switch between infusion state and blood collection state through automatic sliding of the valve core component, thereby eliminating the risk caused by residual blood in the connector from the root and improving the safety and convenience of clinical use.

[0006] Therefore, the present invention provides an indwelling needle, comprising:

[0007] Needle components, including puncture needles and flexible needles;

[0008] The flexible tube is fixedly connected to the flexible needle at one end and communicates with the flexible needle.

[0009] The conversion shell is connected to the other end of the tubing, and an infusion connector and a blood collection connector are also fixedly installed on the conversion shell; a conversion chamber is formed inside the conversion shell;

[0010] A valve core is disposed within the conversion chamber. The valve core includes an inner cylinder layer and an outer cylinder layer. The inner cylinder layer encloses a blood collection chamber, and the inner and outer cylinder layers enclose an infusion chamber. The infusion chamber and the blood collection chamber are spaced apart. A first blood collection port communicating with the blood collection chamber is formed on the front end wall of the inner cylinder layer along its axial direction. A first infusion port is provided on one side of the outer cylinder layer along its radial direction, and a second blood collection port and a second infusion port are provided on the other side. Both the first and second infusion ports are communicating with the infusion chamber. The second blood collection port is communicating with the blood collection chamber through an interlayer channel. A first sealing ring is fitted around the rear periphery of the outer cylinder layer. The rear part of the outer cylinder layer, the first sealing ring, and the inner wall of the conversion shell enclose a balance chamber. The balance chamber communicates with the outside atmosphere through a vent provided on the conversion shell.

[0011] An elastic element is disposed inside the switching cavity, with one end abutting against the valve core and the other end abutting against the inner wall of the switching housing;

[0012] The valve core has an initial infusion state where the first infusion port is aligned with the infusion connector and the second infusion port is aligned with the tubing, and a negative pressure is formed in the blood collection connector, the elastic element is compressed by the pressure difference between the balance chamber and the negative pressure, the valve core slides towards the front end, and the second blood collection port is aligned with the tubing; when the negative pressure disappears, the valve core slides towards the rear end under the action of the elastic force of the elastic element, and returns to the initial infusion state.

[0013] Furthermore, the outer periphery of the outer cylinder extends outward to form a first limiting step, and one end of the elastic element abuts against the front wall surface of the first limiting step; the inner wall of the conversion shell is provided with a second limiting step corresponding to the first limiting step, and when the valve core is in the initial infusion state, the rear wall surface of the first limiting step abuts against the second limiting step.

[0014] Furthermore, the inner wall of the conversion shell is also provided with a third limiting step, which is located at the front end of the first limiting step and the second limiting step; when the valve core is in the blood collection state, the front wall surface of the first limiting step abuts against the third limiting step.

[0015] Furthermore, the indwelling needle also includes:

[0016] The second sealing ring is fitted onto the outer cylinder layer and is located between the second blood collection port and the second infusion port; when the valve core is in the blood collection state and the initial infusion state, the second sealing ring is in sealing contact with the inner wall of the conversion shell.

[0017] Furthermore, the indwelling needle also includes:

[0018] The third sealing ring is fitted onto the outer cylinder layer and is located on the side of the second infusion port away from the second blood collection port; when the valve core is in the initial infusion state, the third sealing ring is in sealing contact with the inner wall of the conversion shell.

[0019] Furthermore, a first sealing mounting groove, a second sealing mounting groove, and a third sealing mounting groove are sequentially provided on the outer wall of the outer cylinder layer, and a first sealing ring, a second sealing ring, and a third sealing ring are respectively disposed in the first sealing mounting groove, the second sealing mounting groove, and the third sealing mounting groove.

[0020] Furthermore, there is a pre-set length outer cylinder layer between the front wall of the first limiting step and the front end wall of the valve core, and the pre-set length outer cylinder layer forms the first mounting and positioning part, with one end of the elastic member sleeved outside the first mounting and positioning part.

[0021] Furthermore, a second mounting and positioning part corresponding to the first mounting and positioning part is provided inside the conversion housing, and the other end of the elastic member is sleeved outside the second mounting and positioning part.

[0022] Furthermore, the second mounting and positioning part is a hollow annular column part, which surrounds the blood collection port corresponding to the blood collection connector.

[0023] Furthermore, the elastic components are made of medical-grade stainless steel.

[0024] The technical solution of this invention has the following advantages:

[0025] The indwelling needle provided by this invention integrates and completely isolates the blood collection chamber and the infusion chamber by setting a valve core component that includes an inner cylinder layer and an outer cylinder layer. This achieves complete separation of the infusion and blood collection channels, fundamentally preventing cross-mixing of infusion fluid and blood, eliminating the problem of residual blood in the tubing, and improving the safety of the indwelling needle. At the same time, by setting a valve core component, an elastic element, and a balance chamber, the valve core component is automatically slid by the pressure difference between the negative pressure formed in the blood collection connector and the balance chamber, realizing automatic switching from infusion state to blood collection state. When the negative pressure disappears, the valve core component automatically returns to the infusion state under the reset elastic force of the elastic element. The entire switching process does not require medical staff to manually operate the switching valve or switch, simplifying the operation steps and improving clinical work efficiency. Attached Figure Description

[0026] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the structure of the indwelling needle provided in an embodiment of the present invention;

[0028] Figure 2 This is a cross-sectional view of the conversion shell and valve core when the indwelling needle is in the initial infusion state, as provided in an embodiment of the present invention;

[0029] Figure 3 This is a cross-sectional view of the conversion shell and valve core when the indwelling needle is in the blood collection state, as provided in an embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram of the valve core component in the indwelling needle provided in an embodiment of the present invention;

[0031] Figure 5 A cross-sectional view of the valve core component in the indwelling needle provided in an embodiment of the present invention;

[0032] Explanation of reference numerals in the attached figures:

[0033] 1-Needle tip; 11-Puncture needle; 12-Soft needle; 2-Ultrasound; 3-Conversion shell; 3a-Balance chamber; 31-Ventilation port; 32-Second limiting step; 33-Third limiting step; 34-Second mounting and positioning part; 4-Infusion connector; 5-Blood collection connector; 6-Valve core; 61-Inner cylinder layer; 611-Blood collection chamber; 612-First blood collection connection port; 62-Outer cylinder layer; 621-Infusion chamber; 622-First infusion connection port; 623-Second blood collection connection port; 624-Second infusion connection port; 625-Interlayer channel; 626-First limiting step; 627-First sealing mounting groove; 628-Second sealing mounting groove; 629-Third sealing mounting groove; 7-Elastic element; 8-First sealing ring; 9-Second sealing ring; 10-Third sealing ring. Detailed Implementation

[0034] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0036] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0037] It is important to note that the constructions and arrangements of this application shown in several different exemplary embodiments are merely illustrative. Although only a few embodiments are described in detail in this disclosure, those who consult this disclosure will readily understand that many modifications are possible (e.g., changes in the size, dimensions, structure, shape, and proportions of various elements, as well as parameter values ​​(e.g., temperature, pressure, etc.), mounting arrangements, use of materials, color, orientation, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in this application). For example, an element shown as integrally formed may be composed of multiple parts or elements, the position of elements may be inverted or otherwise altered, and the nature or number or position of discrete elements may be changed or altered. Therefore, all such modifications are intended to be included within the scope of the invention. The order or sequence of any process or method steps may be changed or rearranged according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure described herein that performs the function, and not only structurally equivalent but also equivalent in structure. Other substitutions, modifications, alterations, and omissions may be made in the design, operation, and arrangement of the exemplary embodiments without departing from the scope of the invention. Therefore, the present invention is not limited to the specific embodiments, but extends to various modifications that still fall within the scope of the appended claims.

[0038] Furthermore, to provide a concise description of exemplary embodiments, not all features of actual embodiments (i.e., those features not relevant to the currently considered best mode for carrying out the invention, or those features not relevant to implementing the invention) may be described. Moreover, the technical features involved in the different embodiments of the invention described below may be combined with each other as long as they do not conflict with each other.

[0039] Please refer to Figures 1-5 This is a schematic diagram of an indwelling needle provided in an embodiment of the present invention.

[0040] like Figures 1-3 As shown, the indwelling needle in this embodiment includes a needle tip 1, a flexible tube 2, a conversion shell 3, a valve core 6, and an elastic element 7.

[0041] like Figure 1 As shown, the needle assembly 1 includes a puncture needle 11 and a soft needle 12. The puncture needle 11 is used to puncture blood vessels, and the soft needle 12 is fitted over the puncture needle 11. After the puncture is completed, the puncture needle 11 is withdrawn, and the soft needle 12 remains in the patient's blood vessel.

[0042] like Figure 1 As shown, one end of the flexible tube 2 is fixedly connected to and communicates with the flexible needle 12, and the other end is connected to the conversion shell 3 and communicates with the conversion cavity inside the conversion shell 3.

[0043] like Figure 1 As shown, an infusion connector 4 and a blood collection connector 5 are also fixedly installed on the conversion shell 3; a conversion cavity is formed inside the conversion shell 3.

[0044] In this embodiment, both the infusion connector 4 and the blood collection connector 5 are connected to the conversion chamber; specifically, the conversion shell 3 is provided with an infusion port and a blood collection port corresponding to the infusion connector 4 and the blood collection connector 5, respectively. In specific implementation, such as... Figures 1-3 As shown, the blood collection connector 5 can be positioned at the front end of the conversion housing 3 along its axial direction (in...). Figures 1-3 In the position shown, the left end is the front end and the right end is the rear end); the hose 2 is located on the lower side of the conversion shell 3 in the radial direction, and correspondingly, the infusion connector 4 is located on the upper side of the conversion shell 3 in the radial direction.

[0045] Specifically, the infusion connector 4 is used to connect an external infusion set; the infusion connector 4 is equipped with sealing components such as a heparin cap or a needleless connector (compatible with a male Luer connector).

[0046] Specifically, the blood collection connector 5 is used to connect blood collection devices, such as blood collection syringes or vacuum blood collection tubes connected to disposable blood collection needles; the blood collection connector 5 is provided with a heparin cap, and the setting method of the heparin cap is consistent with the conventional setting method of the heparin cap in existing indwelling needle products, which will not be described in detail in this embodiment.

[0047] like Figures 2-5 As shown, the valve core 6 is disposed within the switching chamber. The valve core 6 includes an inner cylinder layer 61 and an outer cylinder layer 62. The inner cylinder layer 61 encloses a blood collection chamber 611, and the inner cylinder layer 61 and the outer cylinder layer 62 enclose an infusion chamber 621, which is spaced apart from the blood collection chamber 611. A first blood collection port 612 communicating with the blood collection chamber 611 is formed on the axial front end wall of the inner cylinder layer 61. A first infusion port 622 is provided on one side of the radial direction of the outer cylinder layer 62, and a second blood collection port 623 and a second infusion port 624 are provided on the other side. Both the first infusion port 622 and the second infusion port 624 are connected to the infusion chamber 621. The second blood collection port 623 is connected to the blood collection chamber 611 through an interlayer channel 625. A first sealing ring 8 is fitted around the rear periphery of the outer cylinder layer 62. The rear part of the outer cylinder layer 62, the first sealing ring 8 and the inner wall of the conversion shell 3 form a balance cavity 3a. The balance cavity 3a is connected to the outside atmosphere through the vent 31 provided on the conversion shell 3.

[0048] In specific implementation, a first sealing installation groove 627 can be provided on the outer wall of the outer cylinder layer 62, and a first sealing ring 8 can be provided in the first sealing installation groove 627.

[0049] In this embodiment, to further prevent blood and injection fluid from seeping into the gap between the valve core 6 and the switching chamber and causing mixing and contamination, and to further improve the safety of the terminal indwelling needle in this embodiment, such as... Figure 2 and Figure 3 As shown, the indwelling needle in this embodiment may also include a second sealing ring 9, which is sleeved on the outer cylinder layer 62 and located between the second blood collection port 623 and the second infusion port 624; when the valve core 6 is in the blood collection state and the initial infusion state, the second sealing ring 9 is in sealed contact with the inner wall of the conversion shell 3.

[0050] In this embodiment, based on the negative pressure generated by the blood collection action in the blood collection chamber 611 and the second blood collection port 623 connected to the blood collection chamber 611, the possibility of blood entering the gap between the valve core 6 and the conversion chamber is small; on this basis, a sealed interval is formed between the first sealing ring 8 and the second sealing ring 9 to isolate the blood from the injection solution and prevent them from mixing.

[0051] In specific implementation, a second sealing installation groove 628 can be provided on the outer wall of the outer cylinder layer 62, and the second sealing ring 9 can be provided in the second sealing installation groove 628.

[0052] In this embodiment, to further improve the safety of the indwelling needle, such as... Figure 2 and Figure 3As shown, the indwelling needle in this embodiment may also include a third sealing ring 10, which is sleeved on the outer cylinder layer 62 and located on the side of the second infusion port 624 away from the second blood collection port 623; when the valve core 6 is in the initial infusion state, the third sealing ring 10 is in sealing contact with the inner wall of the conversion shell 3.

[0053] At this time, when the valve core 6 is in the initial infusion state, the third sealing ring 10 seals against the inner wall of the conversion shell 3, blocking the unused blood collection channel area, further improving the airtightness of the infusion passage, and preventing leakage of infusion fluid and intrusion of external impurities.

[0054] In specific implementation, a third sealing installation groove 629 can be provided on the outer wall of the outer cylinder layer 62, and the first sealing ring 8 can be provided in the third sealing installation groove 629.

[0055] like Figure 2 and Figure 3 As shown, the elastic element 7 is disposed in the conversion cavity, with one end abutting against the valve core 6 and the other end abutting against the inner wall of the conversion shell 3.

[0056] In practice, the elastic component 7 can be made of medical-grade stainless steel to ensure its biocompatibility and the stability of its elastic properties.

[0057] In this embodiment, the indwelling needle valve core 6 has an initial infusion state in which the first infusion port 622 is aligned with the infusion connector 4 and the second infusion port 624 is aligned with the tubing 2. In the blood collection connector 5, a negative pressure is formed, and the elastic element 7 is compressed by the pressure difference between the balance chamber 3a and the negative pressure. The valve core 6 slides towards the front end, and the second blood collection port 623 is aligned with the tubing 2. When the negative pressure disappears, the valve core 6 slides towards the rear end under the action of the reset elastic force of the elastic element 7, returning to the initial infusion state.

[0058] As an optional specific implementation of this embodiment, in order to ensure the alignment accuracy of the first infusion connection port 622 and the second connection port when the valve core 6 is in the initial infusion state, especially the precise limiting of the valve core 6 after it resets from the blood collection state to the initial infusion state, to avoid excessive backward slippage and ensure accurate alignment of the infusion passage, such as... Figure 2 and Figure 3 As shown, the outer periphery of the outer cylinder layer 62 can be extended to form a first limiting step 626, and one end of the elastic member 7 abuts against the front wall surface of the first limiting step 626; the inner wall of the conversion shell 3 is provided with a second limiting step 32 corresponding to the first limiting step 626. When the valve core 6 is in the initial infusion state, the rear wall surface of the first limiting step 626 abuts against the second limiting step 32.

[0059] In this embodiment, to improve the structural stability and practicality of the indwelling needle, such as... Figure 2 and Figure 3 As shown, a predetermined length of outer cylinder layer 62 can be provided between the front wall surface of a limiting step and the front end wall of the valve core 6. The predetermined length of outer cylinder layer 62 forms a first mounting and positioning part, and one end of the elastic member 7 is sleeved outside the first mounting and positioning part.

[0060] At this point, the conversion housing 3 can be further configured to have a second mounting positioning part 34 corresponding to the first mounting positioning part, and the other end of the elastic member 7 can be sleeved on the second mounting positioning part 34.

[0061] At this point, in order to improve the structural compactness of the indwelling needle in this embodiment, such as Figure 2 As shown, the second mounting and positioning part 34 can be set as a hollow annular part, which surrounds the blood collection port corresponding to the blood collection connector 5.

[0062] As an optional implementation of this embodiment, in order to limit the maximum sliding stroke of the valve core 6, avoid excessive forward movement of the valve core 6 leading to structural misalignment and flow channel displacement, and ensure accurate alignment of the blood collection pathway, such as... Figure 2 and Figure 3 As shown, the inner wall of the conversion shell 3 can also be provided with a third limiting step 33, which is located at the front end of the first limiting step 626 and the second limiting step 32; when the valve core 6 is in the blood collection state, the front wall surface of the first limiting step 626 abuts against the third limiting step 33.

[0063] The specific working process of the indwelling needle in this embodiment is as follows:

[0064] In the initial infusion state, the valve core 6 is attached to the second limiting step 32 under the pre-tightening force of the elastic element 7. At this time, the first infusion port 622 of the outer cylinder layer 62 is precisely aligned with the infusion connector 4, the second infusion port 624 is precisely aligned with the tubing 2, and the infusion chamber 621 is fully open. An infusion passage is formed in the indwelling needle, consisting of the infusion connector 4, the first infusion port 622, the infusion chamber 621, the second infusion port 624, the tubing 2, and the soft needle 12. At this time, the second blood collection port 623 is in a misaligned and blocked state.

[0065] When blood samples need to be collected, the blood collection device is connected to the blood collection connector 5. The suction from the blood collection device creates negative pressure inside the blood collection connector 5. At this time, the balance chamber 3a is connected to the outside atmosphere through the vent 31, maintaining normal pressure. The pressure difference pushes the valve core 6 to slide forward against the elastic force of the elastic element 7 until the first limiting step 626 abuts against the third limiting step 33, completing the stroke limit, and the indwelling needle enters the blood collection state. At this time, a blood collection passage is formed inside the indwelling needle, consisting of the tubing 2, the second blood collection connection port 623, the interlayer channel 625, the first blood collection connection port 612, and the blood collection connector 5. Simultaneously, the outer cylinder layer 62 of the valve core 6 blocks and seals the infusion connector 4, cutting off the infusion passage.

[0066] After blood collection is completed, the blood collection device is removed. The negative pressure inside the blood collection connector 5 disappears quickly, the pressure difference is balanced, and the valve core 6 slides backward under the reset elastic force of the elastic element 7 until the first limit step 626 abuts against the second limit step 32, automatically returning to the initial infusion state, reconnecting the infusion passage and blocking the blood collection passage. No manual adjustment is required, making the operation convenient.

[0067] In this embodiment, the indwelling needle integrates and completely isolates the blood collection chamber 611 and the infusion chamber 621 by setting a valve core 6, which includes an inner cylinder layer 61 and an outer cylinder layer 62. This achieves complete separation of the infusion and blood collection channels, fundamentally preventing cross-mixing of infusion fluid and blood, eliminating residual blood in the tubing, and improving the safety of the indwelling needle. At the same time, by setting the valve core 6, the elastic element 7, and the balance chamber 3a, the valve core 6 is automatically slid by the pressure difference between the negative pressure formed in the blood collection connector 5 and the balance chamber 3a, realizing automatic switching from infusion state to blood collection state. When the negative pressure disappears, the valve core 6 automatically returns to the infusion state under the reset elastic force of the elastic element 7. The entire switching process does not require medical staff to manually operate the switching valve or switch, simplifying the operation steps and improving clinical work efficiency.

[0068] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An indwelling needle, characterized in that, include: Needle components, including puncture needles and flexible needles; A flexible tube, one end of which is fixedly connected to and communicates with the flexible needle; A conversion shell is connected to the other end of the tubing, and an infusion connector and a blood collection connector are fixedly installed on the conversion shell; a conversion cavity is formed inside the conversion shell; A valve core is disposed within the conversion chamber. The valve core includes an inner cylinder layer and an outer cylinder layer. The inner cylinder layer encloses a blood collection chamber, and the inner and outer cylinder layers enclose an infusion chamber. The infusion chamber and the blood collection chamber are spaced apart. A first blood collection port communicating with the blood collection chamber is formed on the axial front end wall of the inner cylinder layer. A first infusion port is provided on one side of the radial direction of the outer cylinder layer, and a second blood collection port and a second infusion port are provided on the other side. Both the first and second infusion ports are connected to the infusion chamber. The second blood collection port is connected to the blood collection chamber through an interlayer channel. A first sealing ring is sleeved on the rear outer periphery of the outer cylinder layer. A balance chamber is formed between the rear of the outer cylinder layer, the first sealing ring, and the inner wall of the conversion shell. The balance chamber communicates with the outside atmosphere through a vent hole provided on the conversion shell. An elastic element is disposed in the conversion cavity, with one end abutting against the valve core and the other end abutting against the inner wall of the conversion shell; The valve core has an initial infusion state where the first infusion port is aligned with the infusion connector and the second infusion port is aligned with the tubing, and a negative pressure is formed in the blood collection connector. The elastic element is compressed by the pressure difference between the balance chamber and the negative pressure, and the valve core slides towards the front end, with the second blood collection port aligned with the tubing in a blood collection state. When the negative pressure disappears, the valve core slides towards the rear end under the action of the reset elastic force of the elastic element, returning to the initial infusion state.

2. The indwelling needle according to claim 1, characterized in that, The outer periphery of the outer cylinder extends outward to form a first limiting step, and one end of the elastic element abuts against the front wall surface of the first limiting step; the inner wall of the conversion shell is provided with a second limiting step corresponding to the first limiting step, and when the valve core is in the initial infusion state, the rear wall surface of the first limiting step abuts against the second limiting step.

3. The indwelling needle according to claim 2, characterized in that, The inner wall of the conversion shell is also provided with a third limiting step, which is located at the front end of the first limiting step and the second limiting step; when the valve core is in the blood collection state, the front wall surface of the first limiting step abuts against the third limiting step.

4. The indwelling needle according to any one of claims 1-3, characterized in that, Also includes: The second sealing ring is sleeved on the outer cylinder layer and located between the second blood collection port and the second infusion port; when the valve core is in the blood collection state and the initial infusion state, the second sealing ring is in sealing contact with the inner wall of the conversion shell.

5. The indwelling needle according to claim 4, characterized in that, Also includes: The third sealing ring is sleeved on the outer cylinder layer and located on the side of the second infusion port away from the second blood collection port; when the valve core is in the initial infusion state, the third sealing ring is in sealing contact with the inner wall of the conversion shell.

6. The indwelling needle according to claim 5, characterized in that, The outer wall of the outer cylinder layer is provided with a first sealing installation groove, a second sealing installation groove and a third sealing installation groove in sequence, and the first sealing ring, the second sealing ring and the third sealing ring are respectively disposed in the first sealing installation groove, the second sealing installation groove and the third sealing installation groove.

7. The indwelling needle according to claim 2, characterized in that, There is a predetermined length of outer cylinder layer between the front wall of the first limiting step and the front end wall of the valve core, the predetermined length of outer cylinder layer forms a first mounting and positioning part, and one end of the elastic member is sleeved outside the first mounting and positioning part.

8. The indwelling needle according to claim 7, characterized in that, The conversion housing is provided with a second mounting and positioning part corresponding to the first mounting and positioning part, and the other end of the elastic member is sleeved on the outside of the second mounting and positioning part.

9. The indwelling needle according to claim 8, characterized in that, The second mounting and positioning part is a hollow annular column part, which surrounds the blood collection port corresponding to the blood collection connector.

10. The indwelling needle according to claim 1, characterized in that, The elastic element is made of medical-grade stainless steel.

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