Safety closed type venous blood drawing device

Abstract

The application relates to the technical field of medical bloodletting devices, and discloses a safe and sealed venous bloodletting device which comprises an electric pump, a fixing seat connected with the air inlet of the electric pump through a hose, a constant-pressure cavity arranged in the fixing seat, the constant-pressure cavity being communicated with the air inlet of the electric pump, a needle tube detachably mounted on the fixing seat, an open end of the needle tube being communicated with the constant-pressure cavity, a three-way joint arranged at the liquid suction end of the needle tube, two one-way valves respectively mounted at the other two openings of the three-way joint, one of the one-way valves being connected with a blood storage bag through a hose, and the other one-way valve being connected with a needle through a hose. The electric pump intermittently sucks and fills air, continuous blood drawing and blood discharging are realized, the blood of a patient is delivered into the blood storage bag, the process is simple in operation, is not prone to professional exposure, a smaller needle is adopted, the patient has lower discomfort, the bloodletting speed can be adjusted, the application range is wide, the consumables are convenient to replace, the cost is low, and the clinical practicability is high.

Description

Technical Field

[0001] This invention relates to the field of medical bloodletting devices, specifically to a safe and sealed venous bloodletting device. Background Technology

[0002] Polycythemia vera is a malignant clonal disease of bone marrow hematopoietic stem cells. Phlebotomy is an important treatment for this disease. By regularly releasing blood through the veins, the red blood cell volume, hemoglobin, and hematocrit are rapidly reduced, blood viscosity is decreased, and the risk of serious complications such as thrombosis is reduced. Currently, there are three main types of phlebotomy commonly used in clinical practice: One method involves using a regular blood collection needle connected to a 20ml syringe. Every time the syringe is filled with 20ml of blood, the syringe needs to be disconnected from the blood collection needle, the blood in the syringe is injected into a blood collection bottle, and then blood is drawn again. The disadvantages are that the operation is cumbersome, not closed, and there is a high risk of occupational exposure and cross-contamination. One method involves connecting a blood collection needle to a sterile, sealed blood collection bag (similar to the device used during blood donation). The disadvantages are that the blood collection needle requires a large metal needle (16G, 1.7mm in diameter) to increase the blood flow rate, resulting in significant pain during puncture. During the bloodletting process, the patient needs to frequently clench and unclench their fist to maintain the blood flow rate, which increases the patient's pain. The blood flow rate is greatly affected by the condition of the blood vessel and the puncture technique, requiring the selection of a large blood vessel for puncture. Another method is apheresis, which relies on a blood cell separator to quickly remove excess red blood cells from the blood. The disadvantage is that it requires specialized blood cell separation equipment, and each collection requires the use of a complete set of tubing consumables. The cost of a single treatment is over 3,000 yuan, which is too high and cannot be widely carried out in primary hospitals. Summary of the Invention

[0003] The purpose of this invention is to provide a safe and closed-type venipuncture device to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, this solution provides a safe and closed-loop venous bloodletting device, including an electric pump. The air port of the electric pump is connected to a fixed base via a flexible tube. A constant pressure chamber is provided inside the fixed base and is connected to the air port of the electric pump. A needle tube is detachably installed on the fixed base, and the open end of the needle tube is connected to the constant pressure chamber. The syringe has a three-way valve at the aspiration end, and a one-way valve is installed at the other two openings of the three-way valve. One of the one-way valves is connected to a blood collection bag via a tubing, and the other one-way valve is connected to a needle via a tubing.

[0005] Optionally, a sealing cover is hinged to the fixing base, and a pair of spring hinges are provided on the fixing base. The other leaf of the spring hinge is connected to the sealing cover. When the sealing cover is closed, the sealing cover and the fixing base together press the needle tube tightly.

[0006] Optionally, both the fixing base and the sealing cover are provided with a slot, and a sealing gasket is installed in the slot. During installation, the handle ring at the end of the needle tube is engaged and installed in the slot.

[0007] Optionally, the opening of the slot is chamfered, and the sealing gasket is an arc-shaped rubber gasket.

[0008] Optionally, a switch magnet is provided on the fixing base, and an iron sheet is provided at the bottom of the sealing cover, with the iron sheet corresponding to the switch magnet.

[0009] Optionally, the sealing cap has an observation hole, and a transparent plate is provided on top of the observation hole. The transparent plate is a transparent acrylic plate and is located directly above the needle tube.

[0010] Optionally, the sealing cover has an air hole for venting, a sleeve is provided at the bottom of the air hole, the bottom of the sleeve has an opening, the opening is connected to the constant pressure chamber, a sealing plate for sealing the opening is installed at the bottom of the sleeve, and a tension spring is provided inside the sleeve, the bottom of the tension spring is connected to the sealing plate.

[0011] Optionally, a rotating rod is rotatably mounted on the sealing cover, a handwheel is provided at the top of the rotating rod, and the sleeve is inserted through the bottom of the rotating rod; A movable plate is threaded onto the rotating rod, and a positioning rod is fixedly installed above the movable plate. The positioning rod is slidably inserted into the sealing cover. The tension spring is sleeved on the rotating rod, and the top end of the tension spring is connected to the movable plate.

[0012] Optionally, a rotating shaft is rotatably installed inside the constant pressure chamber. The rotating shaft is configured as a damping rotating shaft. A cam is installed on the top of the rotating shaft. The cam is flush with the push rod inside the needle tube. A groove is provided at the top of the cam. A protrusion is installed at the bottom of the rotating rod. After installation, the protrusion engages with the groove.

[0013] Optionally, the top of the rotating shaft is connected to the cam key, and a buffer spring is provided inside the cam, with the bottom end of the buffer spring connected to the rotating shaft.

[0014] The technical effects and advantages of the present invention are as follows: 1. The electric pump intermittently pumps air to achieve continuous blood drawing and drainage, delivering the patient's blood to the blood storage bag. The process is simple to operate, the blood is completely sealed, there is little risk of occupational exposure, and the safety is good. Due to the use of a smaller needle, the patient experiences less discomfort.

[0015] 2. For elderly patients with poor physical condition and those with cardiovascular diseases, the negative pressure inside the constant pressure chamber can be adjusted by turning the handwheel to reduce the bloodletting speed and the amount of bloodletted in a single session, thereby increasing the applicability of this device.

[0016] 3. The device does not require sophisticated or complex technical equipment. The needles, tubing, three-way valves, blood bags, and syringes used in the bloodletting process are all commonly used disposable consumables in clinical practice. They are low in cost, easy to replace, convenient for clinical use, and highly practical. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the present invention and form part of the specification. They are used together with the following detailed description to explain the present invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the internal structure of the fixing base of the present invention; Figure 3 Appendix to this invention Figure 2 Enlarged structural diagram at point A; Figure 4 This is a schematic diagram of the sealing gasket structure of the present invention; Figure 5 This is a schematic cross-sectional view of the vent and sleeve structure of the present invention; Figure 6 Appendix to this invention Figure 5 Enlarged structural diagram at point B; Figure 7 This is an exploded structural diagram of the rotating shaft and cam of the present invention; Figure 8 This is a schematic diagram of the rotating rod and protrusion of the present invention; Figure 9 This is a schematic diagram of the needle and tee of the present invention.

[0018] Explanation of reference numerals in the attached drawings: 101, electric pump; 102, syringe; 103, blood bag; 104, three-way valve; 105, one-way valve; 106, needle; 201, fixed base; 202, sealing cap; 203, rotating rod; 204, transparent plate; 205, switch magnet; 206, constant pressure chamber; 207, slot; 208, sealing gasket; 209, observation hole; 210, spring hinge; 211, sleeve; 212, iron sheet; 213, sealing plate; 214, protrusion; 215, positioning rod; 216, moving plate; 217, air hole; 218, tension spring; 301, rotating shaft; 302, buffer spring; 303, groove; 304, cam. Detailed Implementation

[0019] To make the aforementioned objectives, features, and advantages of this solution more apparent and understandable, the specific embodiments of this solution are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this solution. However, this solution can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this solution. Therefore, this solution is not limited to the specific embodiments disclosed below.

[0020] According to some embodiments of this solution, a safe and closed-loop venous bloodletting device is provided, for reference. Figures 1 to 9 As shown, the safe and sealed venous bloodletting device includes an electric pump 101, which is a miniature vacuum pump. The air port of the electric pump 101 is connected to a fixed base 201 through a flexible hose. A constant pressure chamber 206 is provided inside the fixed base 201. The constant pressure chamber 206 is a sealed cavity structure and is connected to the air port of the electric pump 101. A needle tube 102 is detachably mounted on the mounting base 201. The needle tube 102 is the syringe barrel of a conventional disposable medical syringe. Its open end (the end where the plunger is located) is connected to the constant pressure chamber 206, allowing the air pressure inside the constant pressure chamber 206 to act on the plunger inside the needle tube 102, providing power for the plunger's movement. The liquid-drawing end of the needle tube 102 (the end away from the plunger) is connected to a tee 104. The tee 104 is a medical tee connector that can divide the tubing into... Two branch lines, the other two openings of the three-way valve 104 are each equipped with a one-way valve 105. The one-way valve 105 is a medical one-way fluid valve. The outlet end of one of the one-way valves 105 is connected to a blood collection bag 103 through a sterile tubing. The blood collection bag 103 is a sterile sealed medical blood collection bag used to collect discharged blood. The inlet end of the other one-way valve 105 is connected to a needle 106 through a sterile tubing. The needle 106 is a medical intravenous puncture needle used to puncture the patient's vein.

[0021] Thus, during patient treatment, the blood bag 103 is placed at a low position, the electric pump 101 draws air, the push rod inside the needle 102 moves backward, the volume of the suction end of the needle 102 increases, and negative pressure is generated inside. At this time, the one-way valve 105 connected to the needle 106 opens, and the one-way valve 105 connected to the blood bag 103 closes. Under the action of negative pressure, the blood in the patient's vein flows into the needle 102 through the needle 106 and the one-way valve 105, completing the blood drawing action. When the electric pump 101 inflates... As the push rod moves forward, the volume inside the needle tube 102 decreases, creating positive pressure inside. At this time, the one-way valve 105 connected to the needle 106 closes, while the one-way valve 105 connected to the blood bag 103 opens. Under the pressure of the push rod, the blood inside the needle tube 102 flows into the blood bag 103 through another one-way valve 105, completing the blood drainage action. By reciprocating the push rod, continuous blood drawing and drainage can be achieved, delivering the patient's blood to the blood bag without disconnecting the connection or requiring manual operation.

[0022] Please refer to Figure 2 A sealing cover 202 is hinged to one side of the fixing base 201. A pair of spring hinges 210 are provided on the fixing base 201. One leaf of each spring hinge 210 is fixedly mounted on the fixing base 201, and the other leaf is fixedly mounted on the sealing cover 202. A torsion spring is installed inside each spring hinge 210 to provide elasticity, allowing the sealing cover 202 to automatically maintain a closed tendency when no external force is applied. When medical personnel open the sealing cover 202, they only need to overcome the elasticity of the torsion spring. When the sealing cover 202 is closed, the sealing cover 202 and the fixing base 201 together press and fix the needle tube 102, ensuring that the needle tube 102 will not shift during operation. For specific implementation, please refer to [reference needed]. Figure 2 To facilitate the opening of the sealing cover 202, the sealing cover 202 is provided with several raised strips to increase friction, and the contact surfaces of the sealing cover 202 and the fixing seat 201 are sealed with rubber gaskets.

[0023] On the side opposite to the sealing cover 202, the fixed base 201 has a slot 207. The two slots 207 are positioned opposite each other. When the sealing cover 202 is closed, the two slots 207 merge into a complete engaging slot. Each slot 207 has a sealing gasket 208 installed inside. The sealing gasket 208 is an elastic rubber gasket. When the needle tube 102 is installed, the handle ring at the end of the needle tube 102 is engaged inside the slot 207. When the sealing cover 202 is closed, the two slots 207 together hold the handle ring in place, and the sealing gasket 208 adheres to the outer wall of the handle ring to achieve a seal, preventing gas inside the constant pressure chamber 206 from leaking from the installation position of the needle tube 102 and ensuring the sealing performance of the constant pressure chamber 206. The sealing gasket 208 can prevent dust from contaminating the slot 207. When the sealing gasket 208 becomes contaminated, it can be directly replaced.

[0024] It should be noted that the opening of the slot 207 is chamfered, which allows the handle of the needle 102 to slide easily into the slot 207 when medical staff insert the needle 102 without getting stuck, greatly improving the ease of installation. At the same time, the sealing gasket 208 is a curved rubber gasket. The curved structure can perfectly fit the circular outer wall of the handle, making the contact area between the sealing gasket 208 and the handle larger and the sealing effect better.

[0025] Please refer to Figure 2 A switch magnet 205 is provided on the fixed base 201. The switch magnet 205 is a permanent magnet, but an electromagnetic magnet can also be used. An iron sheet 212 is provided at the bottom of the sealing cover 202. The iron sheet 212 is a magnetically conductive metal sheet. When the sealing cover 202 is closed, the iron sheet 212 will align with the switch magnet 205. The switch magnet 205 will generate magnetic force to attract the iron sheet 212, thereby firmly locking the sealing cover 202 on the fixed base 201. This prevents the sealing cover 202 from accidentally popping open during operation and increases the adhesion between the sealing cover 202 and the fixed base 201, improving the sealing performance.

[0026] Please refer to Figure 1 , Figure 2 An observation hole 209 is provided in the middle of the sealing cap 202. The observation hole 209 is a through hole that passes through the sealing cap 202. A transparent plate 204 is installed on the top of the observation hole 209. The transparent plate 204 is made of transparent acrylic sheet. The transparent plate 204 is located directly above the needle tube 102. When the sealing cap 202 is closed, medical staff can directly observe the inside of the needle tube 102 through the transparent plate 204, including whether the blood is flowing into the needle tube normally, whether there are air bubbles inside the needle tube, whether there are blood clots, etc., so as to monitor the bloodletting status in real time, detect abnormalities in time, and ensure the safety of the bloodletting process.

[0027] Through the above technical solution, the safe and sealed venous bloodletting device provided by this solution, when in use, the electric pump 101 intermittently draws and inflates. When drawing air, the push rod inside the needle tube 102 moves backward, increasing the volume of the liquid-drawing end of the needle tube 102 and generating negative pressure inside. At this time, the one-way valve 105 connected to the needle 106 opens, and the one-way valve 105 connected to the blood storage bag 103 closes. Under the action of negative pressure, the blood in the patient's vein flows into the needle tube 102 through the needle 106 and the one-way valve 105, completing the blood-drawing action. When the electric pump 101 inflates, the push rod moves forward. As the needle moves, the volume inside the needle 102 decreases, creating positive pressure. At this time, the one-way valve 105 connected to the needle 106 closes, while the one-way valve 105 connected to the blood bag 103 opens. Under the pressure of the push rod, the blood inside the needle 102 flows into the blood bag 103 through another one-way valve 105, completing the blood drainage action. By reciprocating the push rod, continuous blood drawing and drainage can be achieved, delivering the patient's blood to the blood bag 103. This process is simple to operate and does not easily lead to occupational exposure. In practice, a smaller needle 106 is used, resulting in less patient discomfort.

[0028] It should be noted that the electric pump 101 is a miniature vacuum pump. The air inlet and exhaust port of the electric pump 101 are respectively connected to the reversing solenoid valve. Specifically, the reversing solenoid valve has three channels. One channel is connected to the air inlet or exhaust port of the electric pump 101, one channel is connected to the outside atmosphere, and one channel is connected to the constant pressure chamber 206 through a hose. Moreover, a check valve is installed on the hose to prevent pressure from flowing back. During evacuation, the solenoid valve switches, and the constant pressure chamber 206 is connected to the air inlet of the electric pump 101 and the exhaust port of the electric pump 101 is open to the atmosphere, thus extracting the gas in the container and discharging it to the outside. During inflation, the solenoid valve reverses, the air inlet of the electric pump 101 is cut off from the constant pressure chamber 206 and the outside air is drawn in, and the exhaust port of the electric pump 101 is connected to the constant pressure chamber 206, so that the drawn-in gas is pressed into the constant pressure chamber 206 to complete the inflation. In this embodiment, the solenoid valve is switched at regular intervals by the DSP controller, and the pressure is maintained by the check valve to achieve intermittent cycle of pumping and filling the constant pressure chamber 206. The check valve includes a pipe and a baffle hinged in the pipe. The baffle can rotate in one direction under the action of a spring, thereby realizing the one-way passage of fluid. The micro vacuum pump and check valve are existing technologies and will not be described in detail here.

[0029] In some implementations of this solution, reference is made to Figure 4As shown, a vent 217 is provided on one side of the sealing cover 202. The vent 217 is an air inlet used to maintain the air pressure inside the constant pressure chamber 206 and prevent the air pressure inside the constant pressure chamber 206 from being too low, which would cause the blood draw speed to be too fast and cause discomfort to the patient. A sleeve 211 is fixedly installed at the bottom of the vent 217. The sleeve 211 is vertically installed at the bottom of the sealing cover 202. An opening is provided at the bottom of the sleeve 211, which is connected to the constant pressure chamber 206. A sealing plate 213 is installed at the bottom of the sleeve 211. A rubber pad is provided at the contact part between the sealing plate 213 and the sleeve 211. A tension spring 218 is also provided inside the sleeve 211. The bottom end of the tension spring 218 is connected to the top of the sealing plate 213. The tension spring 218 can provide an upward pulling force to tighten the sealing plate 213 on the bottom opening of the sleeve 211 to achieve a seal.

[0030] When the air pressure inside the constant pressure chamber 206 decreases, the external atmospheric pressure pushes the sealing plate 213 downward, and external air enters the constant pressure chamber 206 through the air hole 217 to prevent the air pressure in the constant pressure chamber 206 from being too low.

[0031] For specific implementation, please refer to Figure 5 , Figure 6 A rotating rod 203 is rotatably mounted on the top of the sealing cover 202. The top of the rotating rod 203 extends out of the sealing cover 202, and a handwheel is mounted on the top. The handwheel is a round operating wheel, which makes it convenient for medical staff to rotate the rotating rod 203. The bottom of the rotating rod 203 passes through the sleeve 211 downward. A movable plate 216 is threaded on the rotating rod 203. A positioning rod 215 is fixedly mounted on the top of the movable plate 216. The positioning rod 215 is slidably inserted into the sealing cover 202. The positioning rod 215 can restrict the rotation of the movable plate 216, so that when the rotating rod 203 rotates, the movable plate 216 will not rotate with it, but will move up and down along the axis of the rotating rod 203.

[0032] The tension spring 218 is sleeved on the outside of the rotating rod 203. The top end of the tension spring 218 is connected to the bottom of the moving plate 216, and the bottom end is connected to the top of the sealing plate 213. Thus, when medical staff turn the handwheel to drive the rotating rod 203 to rotate, the rotation of the rotating rod 203 will drive the moving plate 216 to move up and down through the threaded transmission. As the moving plate 216 moves, it will change the tension of the tension spring 218, thereby adjusting the preload of the tension spring 218.

[0033] Specifically, when the rotating rod 203 rotates and drives the moving plate 216 to move downward, the tension of the tension spring 218 decreases and the pre-tightening force decreases. At this time, a higher suction pressure can be maintained inside the constant pressure chamber 206, which is suitable for patients with poor vascular conditions. At this time, the pressure difference between the constant pressure chamber 206 and the needle tube 102 is smaller during bloodletting, ensuring that the bloodletting process is slower and reducing patient discomfort. In this way, medical staff can flexibly adjust the pressure of the constant pressure chamber and adjust the bloodletting flow rate according to the patient's condition to meet the needs of different patients.

[0034] Please refer to Figure 2 The constant pressure chamber 206 is equipped with a rotating shaft 301, which is a damping shaft. A cam 304 is mounted on the top of the rotating shaft 301. The cam 304 is an eccentric wheel structure with a variable outer radius. The position of the cam 304 is flush with the position of the push rod inside the needle tube 102. The outer circumference of the cam 304 can contact the tail end of the push rod. By changing the contact position between the cam 304 and the push rod, the amount of blood drawn in a single session can be controlled.

[0035] In this embodiment, the duration of a single blood draw will change after the negative pressure of the constant pressure chamber 206 is changed. If the longest duration of a single blood draw is t, it is ensured that the suction time of the electric pump 101 is always greater than t for each blood draw. In specific implementation, a micro switch can also be set on the side of the cam 304. The micro switch is electrically connected to the DSP controller. When the push rod inside the needle tube 102 reaches its maximum displacement, the push rod will contact the micro switch and send a signal to the DSP controller, thereby immediately switching the working state of the electric pump 101. By controlling the number of cycles of suction and inflation of the constant pressure chamber 206 by the electric pump 101, the total blood volume of the patient can be changed. Specifically, the more cycles of suction and inflation of the constant pressure chamber 206, the greater the total blood volume.

[0036] Specifically, the top of the cam 304 has a groove 303, and the bottom of the rotating rod 203 has a protrusion 214. When the sealing cover 202 is closed, the protrusion 214 at the bottom of the rotating rod 203 engages with the groove 303 at the top of the cam 304. Thus, when medical staff turn the handwheel to rotate the rotating rod 203, the rotating rod 203 will synchronously drive the cam 304 to rotate through the cooperation of the protrusion 214 and the groove 303. If the patient's blood vessels are in poor condition, the movement of the push rod can be restricted by the cam 304, thereby reducing the amount of blood drawn per session.

[0037] The top of the rotating shaft 301 is connected to the cam 304 by a key. At the same time, a buffer spring 302 is provided inside the cam 304. The bottom end of the buffer spring 302 is connected to the top end of the rotating shaft 301, and the top end is connected to the inside of the cam 304. The buffer spring 302 can provide a buffering effect. When the protrusion 214 is engaged in the groove 303 at the top of the cam 304, the cam 304 can move downward to engage with the protrusion 214.

[0038] It should be noted that all blood-contacting components of this device, including needle 102, three-way valve 104, one-way valve 105, needle 106, and blood bag 103, are disposable sterile medical components that can be discarded after use, thus avoiding the risk of cross-infection. Non-contact components such as fixing base 201, electric pump 101, and sealing cap 202 can be repeatedly sterilized and reused, reducing the cost of treatment.

[0039] The working process of this device is as follows: Medical staff first prepare disposable sterile components, including needle 102, three-way valve 104, one-way valve 105, needle 106, blood collection bag 103 and tubing. Then, they open the sealing cover 202 of the fixing base 201, put the needle 102 into the slot 207 of the fixing base 201, align the open end of the needle 102 with the constant pressure chamber 206, and then close the sealing cover 202. The sealing cover 202 closes under the action of the spring hinge 210, and the switch magnet 205 attracts the iron piece 212 to lock the sealing cover 202. At this time, the handle ring of the needle 102 is sealed and fixed by the slot 207 and the sealing gasket 208, completing the installation of the needle 102. Next, the medical staff will adjust the constant pressure according to the patient's condition, turn the handwheel to adjust the position of the moving plate 216, thereby adjusting the preload of the tension spring 218 and setting an appropriate constant pressure. For example, for young patients with good blood vessel conditions, the negative pressure required for blood drawing will be adjusted to a lower level to speed up the blood collection speed. For elderly patients with fragile blood vessels, the negative pressure required for blood drawing will be adjusted to a higher level to avoid blood vessel damage. When the electric pump 101 is started, it intermittently pumps and fills the constant pressure chamber 206. The pressure inside the constant pressure chamber 206 switches between negative and positive pressure, thereby achieving the effect of bloodletting and blood drainage. During the bloodletting process, medical staff can observe the situation inside the needle tube 102 through the observation hole 209 at any time to monitor the bloodletting status.

[0040] The preferred embodiments of this solution have been described in detail above with reference to the accompanying drawings. However, this solution is not limited to the specific details in the above embodiments. Within the scope of the technical concept of this solution, various simple modifications can be made to the technical solution, and these simple modifications all fall within the protection scope of this solution.

[0041] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable way without contradiction. In order to avoid unnecessary repetition, this solution will not describe the various possible combinations separately.

[0042] Furthermore, various implementations of this solution can be combined in any way, as long as they do not violate the spirit of this solution, they should also be regarded as the content disclosed in this solution.

Claims

1. A safe, closed-loop venous bloodletting device, comprising an electric pump (101), characterized in that: The air inlet of the electric pump (101) is connected to a fixed base (201) via a hose. A constant pressure chamber (206) is provided inside the fixed base (201). The constant pressure chamber (206) is connected to the air inlet of the electric pump (101). A needle tube (102) is detachably installed on the fixed base (201). The open end of the needle tube (102) is connected to the constant pressure chamber (206). The syringe (102) has a three-way valve (104) at the liquid aspiration end. The other two openings of the three-way valve (104) are equipped with one-way valves (105). One of the one-way valves (105) is connected to a blood storage bag (103) through a hose, and the other one-way valve (105) is connected to a needle (106) through a hose.

2. The safe and sealed venous bloodletting device according to claim 1, characterized in that: A sealing cap (202) is hinged to the fixing base (201). A pair of spring hinges (210) are provided on the fixing base (201). Another leaf of the spring hinge (210) is connected to the sealing cap (202). After the sealing cap (202) is closed, the sealing cap (202) and the fixing base (201) together press the needle tube (102) tightly.

3. The safe and sealed venous bloodletting device according to claim 2, characterized in that: Both the fixing base (201) and the sealing cover (202) are provided with slots (207), and a sealing gasket (208) is installed in the slots (207). During installation, the handle ring at the end of the needle tube (102) is engaged and installed in the slots (207).

4. The safe and sealed venous bloodletting device according to claim 3, characterized in that: The opening of the slot (207) is chamfered, and the sealing gasket (208) is an arc-shaped rubber gasket.

5. A safe, closed-type venous bloodletting device according to claim 2, characterized in that: A switch magnet (205) is provided on the fixed base (201), and an iron sheet (212) is provided at the bottom of the sealing cover (202). The iron sheet (212) is correspondingly provided with the switch magnet (205).

6. A safe, closed-loop venous bloodletting device according to claim 2, characterized in that: The sealing cap (202) has an observation hole (209), and a transparent plate (204) is provided on the top of the observation hole (209). The transparent plate (204) is a transparent acrylic plate, and the transparent plate (204) is located directly above the needle tube (102).

7. A safe, closed-loop venous bloodletting device according to claim 2, characterized in that: The sealing cover (202) has an air hole (217) for venting. A sleeve (211) is provided at the bottom of the air hole (217). The bottom of the sleeve (211) has an opening that communicates with the constant pressure chamber (206). A sealing plate (213) for sealing the opening is installed at the bottom of the sleeve (211). A tension spring (218) is provided inside the sleeve (211). The bottom of the tension spring (218) is connected to the sealing plate (213).

8. A safe, closed-loop venous bloodletting device according to claim 7, characterized in that: A rotating rod (203) is rotatably mounted on the sealing cover (202). A handwheel is provided at the top of the rotating rod (203), and the sleeve (211) is inserted through the bottom of the rotating rod (203). A movable plate (216) is threaded onto the rotating rod (203), and a positioning rod (215) is fixedly installed above the movable plate (216). The positioning rod (215) is slidably inserted into the sealing cover (202). The tension spring (218) is sleeved on the rotating rod (203), and the top end of the tension spring (218) is connected to the movable plate (216).

9. A safe, closed-type venous bloodletting device according to claim 8, characterized in that: The constant pressure chamber (206) is rotatably mounted with a rotating shaft (301). The rotating shaft (301) is configured as a damping rotating shaft. A cam (304) is mounted on the top of the rotating shaft (301). The cam (304) is flush with the push rod inside the needle tube (102). A groove (303) is provided at the top of the cam (304). A protrusion (214) is mounted on the bottom of the rotating rod (203). After installation, the protrusion (214) engages with the groove (303).

10. A safe, closed-loop venous bloodletting device according to claim 9, characterized in that: The top of the rotating shaft (301) is keyed to the cam (304), and a buffer spring (302) is provided inside the cam (304). The bottom end of the buffer spring (302) is connected to the rotating shaft (301).

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