Closed indwelling catheter blood sampling device

Abstract

The invention belongs to the technical field of medical instruments, and particularly relates to a closed type indwelling catheter blood sampling device. According to the closed type indwelling catheter blood sampling device, the communication state of the three-way pipeline can be adjusted by rotating the switching valve, diluted blood is pumped out through the injection assembly, then the injection assembly is kept still, the communication state of the three-way pipeline is switched, and a blood sampling test tube for collecting blood needing to be inspected is inserted into the needle cover through the insertion opening in the needle cover; the head of the hollow needle head can be inserted into the blood collection test tube, blood needing to be inspected directly enters the blood collection test tube, and the blood collection test tube is taken down from the hollow needle head until the blood needing to be inspected is completely sucked; the communicating state of the three-way pipeline is switched again, the diluted blood in the injection assembly is injected back into the indwelling catheter, blood drawing work in the indwelling catheter is completed, the indwelling catheter does not need to be repeatedly connected and disconnected through a plurality of injectors in the whole process, the blood drawing step is simplified, and the risk of catheter related blood flow infection is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of medical devices, and in particular relates to a closed indwelling catheter blood sampling device. Background Art

[0002] Patients with a peripherally inserted central catheter (PICC) or central venous catheter (CVC) require regular blood draws and tests, including routine blood tests, biochemistry tests, coagulation tests, and blood gas analysis, during the catheterization period. This allows clinicians to assess the patient's recent treatment response and provide a basis for subsequent adjustments to the treatment plan. For example, oncology / hematology patients require weekly blood draws; ICU patients require blood draws up to several times daily, depending on the severity of their illness; and other patients require follow-up examinations based on their condition.

[0003] Currently, there are three methods: central venous catheter blood drawing and pushing method, abandoned blood method and dead space method; among them, The discarded blood method includes the following steps: First, draw 3-6 ml of blood with a 10 ml syringe and discard the drawn 3-6 ml of blood; Take a new sterile syringe and connect it to the central venous catheter to draw the blood sample to be tested, and insert the needle of the syringe into the blood collection tube to inject the blood sample to be tested in the syringe into the blood collection tube so that the blood sample can be sent to the testing center for testing; Finally, flush the central venous catheter with 10 ml of normal saline using a syringe.

[0004] The above process has the following problems and risks: 1) Before injecting the blood to be tested in the syringe into the blood collection tube, the needle must be pierced through the tube cap and inserted into the tube. During this process, medical staff may be easily injured by the needle. 2) During the blood draw process, multiple syringes are required to repeatedly connect and disconnect the central venous catheter, which can easily lead to catheter-related bloodstream infection in patients; 3) Each time blood is drawn, the diluted blood in the central venous catheter needs to be discarded. After multiple blood draws, the patient may experience anemia symptoms; 4) The blood drawing process is cumbersome, time-consuming and labor-intensive.

[0005] Therefore, inventing a blood collection device that is easy to operate and will not injure medical staff is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0006] The present invention provides a closed indwelling catheter blood sampling device to solve the technical problems in the prior art that the blood drawing process in the central venous catheter is complicated and easy to injure medical staff.

[0007] The present invention is achieved through the following technical solutions: A closed indwelling catheter blood collection device, comprising an injection component, a blood collection component and a three-way pipe; The blood collection assembly includes a needle cover and a hollow needle; the needle cover is a tubular structure, one end of the needle cover is provided with an insertion port for facilitating the insertion of a blood collection tube, and the other end of the needle cover is closed; the head of the hollow needle is inserted into the needle cover through the closed end of the needle cover; A switching valve is provided in the three-way pipe, and the pipe mouth A of the three-way pipe is connected to the indwelling catheter, and the pipe mouths B and pipe mouths C of the three-way pipe are respectively connected to the suction end of the injection assembly and the tail end of the hollow needle; by rotating the switching valve, the pipe mouth B or the pipe mouth C can be connected or disconnected with the pipe mouth A.

[0008] In order to better implement the present invention, further optimization is made in the above structure, wherein the blood collection assembly further includes a protective cover; The protective sleeve is sleeved on the hollow needle, and the head end of the protective sleeve can slide along the axial direction of the hollow needle; in an initial state, the head end of the hollow needle is located inside the protective sleeve.

[0009] In order to better implement the present invention, further optimization is made in the above structure, wherein the protective cover includes a sliding section and an extrusion section; The sliding section and the extrusion section are both tubular structures with two ends connected, and the sliding section and the extrusion section are both sleeved on the hollow needle head. The sliding section and the extrusion section are both made of rubber material, and one end of the extrusion section is connected to the tail of the hollow needle head; The sliding section is connected to one end of the extrusion section away from the tail of the hollow needle, and the sum of the length of the sliding section and the length of the extrusion section is greater than the length of the hollow needle.

[0010] In order to better implement the present invention, further optimization is made in the above structure, and the extrusion section is a bellows-shaped structure.

[0011] In order to better implement the present invention, further optimization is made in the above structure, wherein the injection assembly includes a switch, a syringe, a first piston and a second piston; The syringe is a cylindrical structure with one end closed and the other end open. A first storage cavity and a second storage cavity are provided in the syringe. The closed end of the syringe is provided with a first injection port and a second injection port communicating with the first storage cavity and the second storage cavity, respectively. The nozzle B is communicated with the first injection port or the second injection port via the switch. The first piston and the second piston are slidably arranged in the first storage chamber and the second storage chamber respectively by the open end of the syringe, and 0.9% physiological saline is set in the second storage chamber; by adjusting the state of the switch, the first injection port or the second injection port is connected or disconnected with the tube port B.

[0012] In order to better implement the present invention, further optimization is made in the above structure, the volume of the first storage chamber is 5 ml, and the volume of the second storage chamber is 10 ml.

[0013] In order to better implement the present invention, further optimization is made in the above structure, wherein the switch includes a valve body and a valve core; The valve body is a tubular structure with one end open and the other end closed. The side wall of the valve body is provided with valve ports A, B, and C. The valve port A is connected to the pipe port B, the valve port B is connected to the first injection port, and the valve port C is connected to the second injection port. The valve core is slidably inserted into the valve body from the open end of the valve body, and an extrusion spring is provided between one end of the valve core located in the valve body and the inner side wall of the closed end of the valve body. A guide channel is provided on the valve core, and one end of the guide channel is always connected to the valve port A; by adjusting the position of the valve core, the other end of the guide channel is connected to the valve port B or the valve port C.

[0014] In order to better realize the present invention, further optimization is made in the above structure, the inner side wall of the valve body is provided with a limiting groove, and the side wall of the valve core is provided with a limiting protrusion matching the limiting groove; when the limiting protrusion is stuck in the limiting groove, the other end of the guide channel is connected to the valve port C.

[0015] In order to better realize the present invention, further optimization is made in the above structure. The closed indwelling catheter blood collection device also includes a connecting hose, one end of which is connected to the pipe opening A, and the end of the connecting hose away from the three-way pipe is detachably connected to the indwelling catheter.

[0016] In order to better implement the present invention, the above structure is further optimized. The end of the connecting hose away from the three-way pipe is provided with a connecting cap, and the inner side wall of the connecting cap is provided with an internal thread matching the external thread on the end of the indwelling catheter.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The closed indwelling catheter blood sampling device provided by the present invention can be connected to the indwelling catheter through the pipe port A of the three-way pipe, and the switching valve is rotated to connect the pipe port B of the three-way pipe with the pipe port A, and the pipe port C is disconnected from the pipe port A. After the diluted blood is drawn out using the injection assembly, the injection assembly is kept stationary; the position of the switching valve is adjusted to connect the pipe port C of the three-way pipe with the pipe port A, and the pipe port B is disconnected from the pipe port A, and then the blood collection tube for collecting the blood to be tested is inserted into the needle cover through the insertion port on the needle cover so that the head of the hollow needle can be inserted into the blood collection tube, so that the blood to be tested directly enters the blood collection tube until the blood to be tested is completely aspirated. Adjust the position of the switching valve to connect the pipe port B of the three-way pipe with the pipe port A again, disconnect the pipe port C from the pipe port A, remove the blood collection tube from the hollow needle, and inject the diluted blood in the injection assembly back into the indwelling catheter to complete the blood drawing work in the indwelling catheter. The whole process does not require repeated connection and disconnection of the indwelling catheter with multiple syringes, thereby simplifying the blood drawing steps and reducing the risk of catheter-related bloodstream infection. At the same time, the hollow needle is located inside the needle cover, which can prevent medical staff from being stabbed by the head of the hollow needle during the blood drawing process, thereby improving the safety of the closed indwelling catheter blood collection device when in use.

[0018] In addition, the diluted blood is drawn out using the injection assembly and kept stationary. After the blood required for testing is drawn out, it can be reinjected into the indwelling catheter, avoiding the occurrence of anemia symptoms in patients due to discarding the diluted blood. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 This is a schematic structural diagram of a closed indwelling catheter blood sampling device according to the present invention; Figure 2 This is a schematic structural diagram of a blood sampling assembly in a closed indwelling catheter blood sampling device according to the present invention; Figure 3 This is a schematic structural diagram of an injection assembly in a closed indwelling catheter blood sampling device according to the present invention; Figure 4 This is a schematic structural diagram of a closed indwelling catheter blood sampling device of the present invention in an initial state during use; Figure 5This is a schematic structural diagram of a closed indwelling catheter blood sampling device according to the present invention after aspirating diluted blood from an indwelling catheter; Figure 6 The invention is a structural schematic diagram of a closed indwelling catheter blood sampling device for collecting blood to be tested in an indwelling catheter.

[0021] In the picture: 1. Blood collection assembly; 11. Needle cover; 12. Hollow needle; 13. Protective cover; 131. Sliding section; 132. Extrusion section; 2. Injection assembly; 21. Switch; 211. Valve body; 212. Valve core; 213. Extrusion spring; 22. Injection cylinder; 23. First piston; 24. Second piston; 3. Tee pipe; 4. Connecting hose; 41. Connecting cap; 5. Blood collection tube. DETAILED DESCRIPTION

[0022] To make the objectives, technical solutions, and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other implementations obtained by those of ordinary skill in the art without inventive effort are within the scope of protection of the present invention.

[0023] In the description of the present invention, it should be noted that, unless otherwise specified, the term "plurality" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front," "rear," "head," "tail," etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings and are intended only to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific direction, be constructed, or operate in a specific direction, and therefore should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0024] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; and direct or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of these terms in the present invention depending on the specific circumstances.

[0025] In an embodiment of the present invention, Figures 1 to 6As shown, the closed indwelling catheter blood collection device includes an injection component 2, a blood collection component 1 and a three-way pipe 3; wherein, The blood collection assembly 1 includes a needle cover 11 and a hollow needle 12; the needle cover 11 is a tubular structure, one end of the needle cover 11 is provided with an insertion port for facilitating the insertion of the blood collection tube 5, and the other end of the needle cover 11 is closed; the head of the hollow needle 12 is inserted into the needle cover 11 through the closed end of the needle cover 11; A switching valve is provided in the three-way pipe 3. The pipe port A of the three-way pipe 3 is connected to the indwelling catheter, and the pipe ports B and pipe ports C of the three-way pipe 3 are connected to the suction end of the injection component 2 and the tail end of the hollow needle 12 respectively; by rotating the switching valve, the pipe port B or the pipe port C can be connected or disconnected with the pipe port A.

[0026] When blood sampling is required in the indwelling catheter, the medical staff can connect the closed indwelling catheter blood sampling device to the indwelling catheter through the pipe port A of the three-way pipe 3, and adjust the position of the switching valve so that the pipe port B of the three-way pipe 3 is connected to the pipe port A, and the pipe port C is disconnected from the pipe port A. Figure 4 ; Then, the diluted blood in the indwelling catheter is drawn out by the injection assembly 2 and the injection assembly 2 is kept stationary, that is, the diluted blood is temporarily stored inside the injection assembly 2. Figure 5 ; Since the interior of the closed indwelling catheter blood collection device is sterile, the diluted blood temporarily stored inside the injection assembly 2 will not be contaminated; Then, the medical staff can adjust the position of the switching valve so that the pipe port C of the three-way pipe 3 is connected to the pipe port A, and the pipe port B is disconnected from the pipe port A. At this time, the medical staff can insert the blood collection tube 5 for collecting the blood to be tested into the needle cover 11 through the insertion port on the needle cover 11 so that the head of the hollow needle 12 can be inserted into the blood collection tube 5. Figure 6 , so that the blood to be tested directly enters the blood collection tube 5 until the blood to be tested is drawn; Finally, the medical staff adjusts the position of the switching valve again so that the pipe port B of the three-way pipe 3 is connected to the pipe port A, and the pipe port C is disconnected from the pipe port A. The blood collection tube 5 is removed from the hollow needle 12, and the diluted blood in the injection component 2 is injected back into the indwelling catheter, completing the blood drawing work in the indwelling catheter.

[0027] During the blood drawing process within the above-mentioned indwelling catheter, medical staff do not need to repeatedly connect and disconnect the indwelling catheter with multiple syringes, thereby simplifying the blood drawing process, saving time and cost, and reducing the risk of catheter-related bloodstream infection; At the same time, in the closed indwelling catheter blood collection device, the hollow needle 12 is located inside the needle cover 11, which can prevent medical staff from being stabbed by the head of the hollow needle 12 during the blood drawing process, thereby improving the safety of the closed indwelling catheter blood collection device when in use.

[0028] In addition, after the diluted blood is drawn out using the injection component 2, the injection component 2 is kept stationary. After the blood required for testing is drawn out, the diluted blood can be re-injected into the indwelling catheter to avoid the patient developing anemia symptoms due to discarding the diluted blood.

[0029] In some embodiments, the blood collection assembly 1 further includes a protective cover 13, see Figure 2 ;in, The protective sleeve 13 is sleeved on the hollow needle 12, and the head end of the protective sleeve 13 can slide along the axis of the hollow needle 12; in the initial state, the head of the hollow needle 12 is located inside the protective sleeve 13 to protect the hollow needle 12; When it is necessary to collect blood for testing, the medical staff will insert the blood collection tube 5 into the needle cover 11 through the insertion port. At this time, the test tube cap will squeeze the head end of the protective sleeve 13 toward the tail end of the hollow needle 12, so that the head of the hollow needle 12 in the protective sleeve 13 is exposed, and the test tube cap is inserted into the blood collection tube 5 to perform the blood drawing operation. Figure 6 ; After completing the blood drawing operation, the medical staff will remove the blood collection tube 5 from the hollow needle 12. At this time, the protective cover 13 will return to its original state and cover the hollow needle 12 to prevent the residual blood in the hollow needle 12 from spilling out.

[0030] Specifically, the protective cover 13 includes a sliding section 131 and an extrusion section 132; wherein, The sliding section 131 and the extruding section 132 are both tubular structures with both ends extending therethrough. The sliding section 131 and the extruding section 132 are both sleeved on the hollow needle 12. The sliding section 131 and the extruding section 132 are both made of rubber material. One end of the extruding section 132 is connected to the tail of the hollow needle 12. The sliding section 131 is connected to the end of the extruding section 132 away from the closed end of the needle shield 11. The sum of the lengths of the sliding section 131 and the extruding section 132 is greater than the length of the hollow needle 12, so that the protective cover 13 in the initial state can completely cover the hollow needle 12, thereby preventing the hollow needle 12 from being exposed. When the medical staff inserts the blood collection test tube 5 into the needle cover 11 through the insertion port, the test tube cap abuts the sliding section 131, and the overall shape of the sliding section 131 does not deform. Under the pressure of the test tube cap, the sliding section 131 presses the extrusion section 132, causing the extrusion section 132 to deform, shortening the overall length of the protective cover 13, thereby exposing the hollow needle 12, which then penetrates the test tube cap and enters the blood collection test tube 5. After the blood drawing operation is completed and the medical staff removes the blood collection tube 5 from the hollow needle 12, the squeezing section 132 will return to its initial state and, during the recovery process, push the sliding section 131 toward the head of the hollow needle 12 and cover the head of the hollow needle 12.

[0031] Preferably, the extrusion section 132 is a bellows structure.

[0032] In some embodiments, the injection assembly 2 includes a switch 21, a syringe 22, a first piston 23 and a second piston 24, see Figure 3 ;in, The syringe 22 is a cylindrical structure with one end closed and the other end open. A first storage cavity and a second storage cavity are provided in the syringe 22. The closed end of the syringe 22 is provided with a first injection port and a second injection port communicating with the first storage cavity and the second storage cavity, respectively. The nozzle B is connected to the first injection port or the second injection port via a switch 21. The first piston 23 and the second piston 24 are slidably disposed in the first storage chamber and the second storage chamber respectively by the open end of the syringe 22, and 0.9% normal saline is disposed in the second storage chamber; When it is necessary to draw blood from the indwelling catheter, the staff can first determine the state of the switch 21, connect the opening of the switch 21 and the tube port B to the first injection port, disconnect the opening of the switch 21 and the tube port B from the second injection port, and connect the switch 21 to the tube port B; at this time, the medical staff can pull the first piston 23 to draw out the diluted blood in the indwelling catheter, and then Figure 5 Then proceed with the subsequent work of drawing the blood required for testing; After completing the blood drawing and injecting the diluted blood back into the indwelling catheter, the medical staff can adjust the state of the switch 21 so that the opening connecting the switch 21 and the tube port B is connected to the second injection port, and the opening connecting the switch 21 and the tube port B is disconnected from the first injection port, and press the second piston 24 to inject the 0.9% saline in the second storage chamber into the indwelling catheter for flushing the indwelling catheter to avoid the indwelling catheter being blocked by residual blood in the indwelling catheter. Figure 1 .

[0033] Preferably, the volume of the first storage chamber is 5 ml. When aspirating diluted blood, the medical staff pulls the first piston 23 to the end of the first storage chamber and stops. The diluted blood inside is exactly 5 ml, which meets the aspiration requirement of diluted blood. The volume of the second storage chamber is 10 ml, and 10 ml of 0.9% saline is stored inside, which is all injected into the indwelling catheter to complete the flushing work; the volume limitation of the first storage chamber and the second storage chamber can further improve the blood drawing efficiency.

[0034] In some embodiments, the switch 21 includes a valve body 211 and a valve core 212. Figure 3 ;in, The valve body 211 is a tubular structure with one end open and the other end closed. Valve ports A, B, and C are provided on the sidewall of the valve body 211. Valve port A is connected to the pipe port B, that is, valve port A is the opening that connects the switch 21 and the pipe port B. Valve port B is connected to the first injection port, and valve port C is connected to the second injection port. The valve core 212 is slidably inserted into the valve body 211 from the open end of the valve body 211. An extrusion spring 213 is provided between one end of the valve core 212 located inside the valve body 211 and the inner side wall of the closed end of the valve body 211. The valve core 212 is provided with a diversion channel, one end of which is always connected to the valve port A. In the initial state, the valve core 212 is always located at the end of the valve body 211 with the opening due to the elastic force of the extrusion spring 213. At this time, the valve port B is connected to the valve port A through the diversion channel. In this state, medical personnel can pull the first piston 23 to draw the diluted blood in the indwelling catheter into the first storage chamber. After the required blood for testing is extracted and the diluted blood in the first storage chamber is injected back into the indwelling catheter, the medical staff can press the valve core 212 to make the valve core 212 overcome the elastic force of the extrusion spring 213 and move to the closed end of the valve body 211. At this time, the valve port C is connected to the valve port A through the diversion channel; in this state, the medical staff can press the second piston 24 to inject the physiological saline in the second storage chamber into the indwelling catheter to achieve the effect of flushing the indwelling catheter.

[0035] Preferably, the inner side wall of the valve body 211 is provided with a limiting groove, and the side wall of the valve core 212 is provided with a limiting protrusion matching the limiting groove; When the limiting protrusion is stuck in the limiting groove, the other end of the diversion channel is connected to the valve port C, so that medical staff can inject 0.9% saline to complete the flushing of the indwelling catheter without continuously pressing the valve body 211, making the flushing of the indwelling catheter easier.

[0036] It is worth noting that since the closed indwelling catheter blood sampling device is a disposable item, it can be removed and discarded after the injection of 0.9% saline is completed. Therefore, there is no need to solve the problem of resetting the valve body 211.

[0037] In some embodiments, the valve body 211 and the syringe 22 are integrally formed components. Figure 3 .

[0038] In some embodiments, the closed indwelling catheter blood collection device further comprises a connecting hose 4, see Figure 1One end of the connecting hose 4 is connected to the pipe opening A, and the end of the connecting hose 4 away from the three-way pipe 3 is detachably connected to the indwelling catheter.

[0039] Preferably, a connecting cap 41 is provided at one end of the connecting hose 4 away from the three-way pipe 3, and the inner side wall of the connecting cap 41 is provided with an internal thread matching the external thread on the end of the indwelling catheter. The connecting hose 4 is detachably connected to the indwelling catheter through the connecting cap 41, so that the use of the closed indwelling catheter blood collection device is more convenient.

[0040] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A closed indwelling catheter blood sampling device, characterized by: It includes an injection component (2), a blood collection component (1) and a three-way pipe (3); The blood collection assembly (1) comprises a needle cover (11) and a hollow needle (12); the needle cover (11) is a tubular structure, one end of the needle cover (11) is provided with an insertion port for facilitating the insertion of a blood collection test tube (5), and the other end of the needle cover (11) is closed; the head of the hollow needle (12) is inserted into the needle cover (11) from the closed end of the needle cover (11); A switching valve is provided in the three-way pipe (3), wherein the pipe opening A of the three-way pipe (3) is connected to the indwelling catheter, and the pipe openings B and C of the three-way pipe (3) are respectively connected to the suction end of the injection assembly (2) and the tail end of the hollow needle (12); by rotating the switching valve, the pipe opening B or the pipe opening C is connected or disconnected with the pipe opening A.

2. The closed indwelling catheter blood sampling device according to claim 1, characterized in that: The blood collection assembly (1) further includes a protective cover (13); The protective sleeve (13) is sleeved on the hollow needle (12), and the head end of the protective sleeve (13) can slide along the axial direction of the hollow needle (12); in an initial state, the head end of the hollow needle (12) is located inside the protective sleeve (13).

3. The closed indwelling catheter blood sampling device according to claim 2, characterized in that: The protective sleeve (13) comprises a sliding section (131) and an extrusion section (132); The sliding section (131) and the extrusion section (132) are both tubular structures with two ends through, and the sliding section (131) and the extrusion section (132) are both sleeved on the hollow needle (12). The sliding section (131) and the extrusion section (132) are both made of rubber material, and one end of the extrusion section (132) is connected to the tail of the hollow needle (12); The sliding section (131) is connected to an end of the extrusion section (132) away from the tail of the hollow needle (12), and the sum of the length of the sliding section (131) and the length of the extrusion section (132) is greater than the length of the hollow needle (12).

4. The closed indwelling catheter blood sampling device according to claim 3, characterized in that: The extrusion section (132) is a bellows-shaped structure.

5. The closed indwelling catheter blood sampling device according to claim 1, characterized in that: The injection assembly (2) includes a switch (21), a syringe (22), a first piston (23) and a second piston (24); The syringe (22) is a cylindrical structure with one end closed and the other end open. A first storage cavity and a second storage cavity are provided in the syringe (22). The closed end of the syringe (22) is provided with a first injection port and a second injection port respectively connected to the first storage cavity and the second storage cavity. The tube port B is connected to the first injection port or the second injection port via the switch (21); The first piston (23) and the second piston (24) are slidably arranged in the first storage chamber and the second storage chamber respectively by the open end of the syringe (22), and 0.9% physiological saline is arranged in the second storage chamber; by adjusting the state of the switch (21), the connection or disconnection of the first injection port or the second injection port with the tube port B is achieved.

6. The closed indwelling catheter blood sampling device according to claim 5, characterized in that: The volume of the first storage chamber is 5 ml, and the volume of the second storage chamber is 10 ml.

7. The closed indwelling catheter blood sampling device according to claim 5, characterized in that: The switch (21) includes a valve body (211) and a valve core (212); The valve body (211) is a tubular structure with one end open and the other end closed. A valve port A, a valve port B, and a valve port C are provided on the side wall of the valve body (211). The valve port A is connected to the pipe port B, the valve port B is connected to the first injection port, and the valve port C is connected to the second injection port. The valve core (212) is slidably inserted into the valve body (211) from the open end of the valve body (211), and an extrusion spring (213) is provided between one end of the valve core (212) located in the valve body (211) and the inner side wall of the closed end of the valve body (211). A guide channel is provided on the valve core (212), and one end of the guide channel is always connected to the valve port A; by adjusting the position of the valve core (212), the other end of the guide channel is connected to the valve port B or the valve port C.

8. The closed indwelling catheter blood sampling device according to claim 7, characterized in that: The inner side wall of the valve body (211) is provided with a limiting groove, and the side wall of the valve core (212) is provided with a limiting protrusion matching the limiting groove; when the limiting protrusion is locked in the limiting groove, the other end of the guide channel is communicated with the valve port C.

9. The closed indwelling catheter blood sampling device according to any one of claims 1 to 8, characterized in that: It also includes a connecting hose (4), one end of which is in communication with the pipe opening A, and one end of which is away from the three-way pipe (3) and is detachably connected to the indwelling catheter.

10. The closed indwelling catheter blood sampling device according to claim 9, characterized in that: The end of the connecting hose (4) away from the three-way pipe (3) is provided with a connecting cap (41), and the inner side wall of the connecting cap (41) is provided with an internal thread matching the external thread on the end of the indwelling catheter.

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