Single-stage venous cannula capable of adjusting infusion amount and flow rate control method thereof

Abstract

The invention relates to the technical field of medical apparatus and instruments, and particularly discloses a single-stage venous cannula capable of adjusting infusion amount and a flow rate control method of the single-stage venous cannula. The adjusting mechanism comprises an adjusting seat, a screw rod and a driving assembly, the outer side of the insertion pipe is sleeved with the adjusting seat, the screw rod is in threaded connection with the interior of the adjusting seat, the end of the screw rod is used for abutting against the insertion pipe, and the driving assembly is used for driving the screw rod to rotate; the driving assembly comprises a connecting column, an inserting rod and a first elastic piece, the connecting column is connected to the screw rod, the inserting rod is movably inserted into the adjusting seat, an inserting piece is arranged on the inserting rod, and an inserting hole for the inserting piece to be inserted in is formed in the connecting column. After the adjustment process is completed, the connection between the insertion rod and the screw rod can be disconnected, so that the situation that the set flow speed is accidentally changed due to the fact that a patient touches by mistake, clothes rub or the transfer process can be effectively prevented, and infusion safety is guaranteed.

Description

Technical Field

[0001] This application relates to the field of medical device technology, and in particular to a single-stage intravenous catheter with adjustable infusion volume and a method for controlling its flow rate. Background Technology

[0002] In clinical intravenous infusion therapy, precise and stable control of the infusion rate is crucial to ensuring patient safety. This is especially true for newborns, elderly patients with heart failure, and patients using high-risk medications, where even minor fluctuations or loss of control in the flow rate can lead to serious medical consequences.

[0003] Currently, gravity-fed infusion sets widely used in clinical practice mainly rely on roller-type regulators to control the flow rate. Their working principle involves rollers moving along a wedge-shaped track, applying unidirectional linear compression to the tubing, flattening the circular tube into a dumbbell-shaped slit to restrict flow. However, this structure has the following drawbacks: during infusion, if the patient turns over or moves, they may accidentally touch the rollers, causing unexpected fluctuations in the infusion rate, posing a safety hazard. Summary of the Invention

[0004] To address the issue of unstable infusion volume during catheterization, this application provides a single-stage venous catheter with adjustable infusion volume and a method for controlling its flow rate.

[0005] In a first aspect, this application provides a single-stage venous catheter with adjustable infusion volume, employing the following technical solution: A single-stage intravenous catheter with adjustable infusion volume, comprising a catheter; The adjustment mechanism includes an adjustment seat, a screw, and a drive assembly. The adjustment seat is sleeved on the outside of the insertion tube, the screw is threaded into the adjustment seat, and the end of the screw is used to abut against the outer wall of the insertion tube located inside the adjustment seat. The drive assembly is used to drive the screw to rotate. The driving assembly includes a connecting post, a plug rod, and a first elastic element. The connecting post is connected to the end of the screw away from the insertion tube. The plug rod is located at the end of the connecting post away from the screw. One end of the plug rod is movably inserted into the adjusting seat. The end of the plug rod near the connecting post is provided with a connector. The connecting post has a socket for the connector to be inserted into, so that when the plug rod rotates after the connector is inserted into the socket, it drives the screw to rotate. The first elastic element is connected to the plug rod and is used to drive the plug rod to slide towards the side away from the connecting post.

[0006] By adopting the above technical solution, the screw feed achieves quantitative compression of the intubation tube, resulting in higher adjustment precision compared to traditional roller structures. Under normal conditions, the insertion part at the end of the intubation tube separates from the insertion hole on the connecting post under the action of the first elastic element. Even if the patient accidentally rotates or pushes the external intubation tube, the screw will not rotate accordingly, thus achieving screw self-locking. This helps prevent unexpected changes in the infusion flow rate due to patient accidental contact or external friction, improving the safety of the infusion process. Furthermore, because the screw has self-locking capability, when the medication solution is changed, causing temperature changes in the intubation tube leading to expansion, the intubation tube is less likely to push the screw, thus ensuring stable compression of the intubation tube by the screw and maintaining a stable infusion volume.

[0007] Optionally, the connector includes a connector ring, the inner wall of which is frustum-shaped, the opening of the connector ring near the connecting post is larger than the opening of the connector ring away from the connecting post, a limiting block is provided on the inner wall of the connector ring, the limiting block is elastic, the insertion hole is annular in shape that matches the connector ring, and a limiting groove is provided on the inner wall of the insertion hole for the limiting block to be inserted.

[0008] By adopting the above technical solution, the frustum surface can act as a guide, allowing the connector to smoothly align and slide into the socket when pressed. The cooperation between the limiting block and the limiting groove stably transmits the rotational torque of the plug rod to the connecting post, eliminating the risk of slippage; while the elastic limiting block can smoothly slide into or out of the limiting groove, ensuring smooth operation.

[0009] Optionally, the axis of the first elastic element is coaxial with the axis of the insertion rod, the first end of the first elastic element is rotatably connected to the insertion rod, and the second end of the first elastic element is connected to the connecting post.

[0010] By adopting the above technical solution, the rotatable connection between the first elastic element and the insert rod eliminates the torsional stress of the first elastic element during rotation, ensuring the reliability of the structure for long-term use. Since the first elastic element is connected to the screw, it can apply pressure to the screw, enhancing the tight fit at the threaded connection and helping to improve the screw's self-locking effect.

[0011] Optionally, the end of the insertion rod located outside the adjustment seat is provided with a handle.

[0012] By adopting the above technical solution, it is easier for medical staff to hold and rotate the insertion rod.

[0013] Optionally, the end of the screw is rotatably connected to an abutment block, the abutment block is slidably connected to the adjusting seat, and the abutment block is used to abut against the insertion tube.

[0014] By adopting the above technical solution, the screw is used to provide feed pressure, while the abutment block that is in direct contact with the insertion tube only makes linear motion. This avoids the rotating screw end directly rubbing and crushing the insertion tube surface, which would cause wear on the tube wall or cause the insertion tube to twist. This helps to ensure the squeezing effect on the insertion tube.

[0015] Optionally, the abutting block is provided with abutting pieces on both sides. The two abutting pieces are used to abut against the opposite sides of the outer peripheral surface of the insertion tube. When the abutting block moves closer to the insertion tube, the two abutting pieces move away from each other. When the abutting block moves away from the insertion tube, the two abutting pieces move closer to each other.

[0016] By adopting the above technical solution, when increasing the infusion volume, the abutment block moves away from the cannula. At this time, the two abutment plates actively close inward, applying lateral squeezing force to the two sides of the already flattened cannula. The lateral pressure causes the flattened lumen to gradually bulge, thereby forcing the cannula to overcome the material's viscosity, quickly restore the circular channel, and increase the infusion volume. This active intervention eliminates the rebound hysteresis of the tube wall material, allowing the increase in infusion volume to respond instantly to the adjustment action, which helps improve the efficiency of the adjustment process. When decreasing the infusion volume, the abutment block moves closer to the cannula. At this time, the two abutment plates move away from each other, providing more deformation space for the cannula. This ensures that the cannula can be flattened and cut off without obstruction, preventing excessive clamping force of the abutment plates from causing too many wrinkles when the cannula is completely flattened, which could lead to the inability to completely shut off the flow rate. Thus, while eliminating hysteresis, it can ensure the adjustment effect of the infusion volume.

[0017] Optionally, the abutting piece and the abutting block are rotatably connected, and a second elastic element is connected between the abutting piece and the abutting block. The second elastic element is used to drive the two abutting pieces to swing towards each other; the ends of the two abutting pieces away from the abutting block are flared.

[0018] By adopting the above technical solution, when the abutment block slides towards the side closer to the insertion tube, the insertion tube is gradually flattened, and the deformed insertion tube pushes the two abutment pieces to swing away from each other. When the abutment block slides away from the insertion tube, the second elastic element drives the two abutment pieces to swing towards the side closer to each other, which can help the tube wall return to its original round shape. Since the ends of the two abutment pieces away from the abutment block are flared, the two abutment pieces swing outward during the screw insertion process, which can prevent the abutment pieces from abutting against the inner wall of the perforation, thus preventing the screw from continuing to be screwed in.

[0019] Optionally, each of the abutting pieces is provided with a connecting block, the connecting block being slidably connected to the abutting block, and a third elastic element being connected between the two connecting blocks, the third elastic element being used to drive the two connecting blocks to slide towards each other; the adjusting seat is provided with a receiving groove for inserting the abutting piece.

[0020] By adopting the above technical solution, when the abutment block slides towards the side closer to the insertion tube, the insertion tube is gradually flattened, and the deformed insertion tube pushes the two abutment pieces to slide away from each other. When the abutment block slides away from the insertion tube, the third elastic element can drive the two abutment pieces to slide towards each other, thereby assisting in the return of the tube wall to a round shape. Because a receiving groove is provided, the abutment pieces can slide into the receiving groove, which can prevent the abutment pieces from abutting against the inner wall of the perforation, thus preventing the screw from continuing to screw in.

[0021] Secondly, this application provides a flow rate control method, which adopts the following technical solution: A flow rate control method includes the following steps: Step S1: Press the plug rod to insert the connector into the socket; Step S2: Rotate the insertion rod, which drives the connecting post and the screw to rotate, and the end of the screw presses against the insertion tube; Step S3: Pull out the insert rod to disengage the connector from the socket, and the first elastic member presses against the insert rod.

[0022] By adopting the above technical solution, pressing and rotating the insertion rod will drive the screw to rotate, thereby adjusting the infusion volume of the catheter. After the adjustment process is completed, the insertion rod is pulled outward, and the connection between the insertion rod and the screw is disconnected. Therefore, even if the patient accidentally touches the insertion rod, the screw will not be driven to rotate, thus ensuring the stability of the infusion volume.

[0023] In summary, this application includes the following beneficial technical effects: 1. When the infusion volume needs to be adjusted, press the plunger inward and then rotate the plunger to drive the screw to rotate, thereby adjusting the infusion volume of the catheter. After the adjustment process is completed, pull the plunger outward to disconnect the connection between the plunger and the screw. This effectively prevents accidental changes in the flow rate setting caused by patient touch, clothing friction, or during transportation, ensuring infusion safety.

[0024] 2. Abutment plates that can open and close in conjunction are provided on both sides of the abutment block. When it is necessary to increase the infusion volume, the abutment block moves away from the insertion tube. Under the action of the second or third elastic element, the abutment plate actively squeezes the side of the insertion tube, forcing the lumen to open. This can reduce the time difference between the adjustment operation and the actual flow change, thereby improving the efficiency of the adjustment process and reducing the adverse effects of the rebound hysteresis of the tubing material. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall structure of Embodiment 1 of this application; Figure 2 This is a cross-sectional view along the axial direction of the insertion cannula in Embodiment 1 of this application; Figure 3 yes Figure 2 A magnified view of a portion of point A in the middle; Figure 4 This is a cross-sectional view of Embodiment 1 of this application along the cross-section of the insertion tube; Figure 5 This is a schematic diagram of the structure of Embodiment 1 of this application with the adjustment seat removed; Figure 6 yes Figure 5 A magnified view of a portion of point B in the middle; Figure 7 This is a cross-sectional view of Embodiment 2 of this application; Figure 8 yes Figure 7 A magnified view of a portion of point C.

[0026] Reference numerals: 1. Insertion tube; 2. Adjustment mechanism; 21. Adjustment seat; 211. Receiving groove; 212. Through hole; 213. Threaded hole; 214. Mounting hole; 215. Guide groove; 216. Cover plate; 22. Screw; 23. Drive assembly; 231. Connecting post; 2311. Insertion hole; 2312. Limiting groove; 232. Insertion rod; 2321. Guide ring; 2322. Handle; 233. First elastic element; 3. Abutment block; 31. Guide post; 32. Slide groove; 4. Insertion piece; 41. Insertion ring; 42. Limiting block; 5. Abutment piece; 6. Second elastic element; 7. Connecting block; 8. Third elastic element. Detailed Implementation

[0027] The following combination Figures 1-8 This application will be described in further detail.

[0028] Example 1: This application discloses a single-stage intravenous catheter with adjustable infusion volume. (Refer to...) Figure 1 The adjustable infusion volume single-stage intravenous cannula includes a cannula 1 and an adjustment mechanism 2 fitted onto the cannula 1. The cannula 1 is a flexible medical polymer soft tube, which runs through the interior of the adjustment mechanism 2. The two ends of the cannula 1 are connected to the medication bottle and the patient's vein, respectively, so that the medication can be delivered into the vein through the cannula 1, allowing the medication to enter the body and achieve the therapeutic purpose.

[0029] Reference Figure 2The adjustment mechanism 2 includes an adjustment seat 21, a screw 22, and a drive assembly 23. The adjustment seat 21 is the external support frame of the adjustment mechanism 2. A through hole 212 is provided on the adjustment seat 21, through which the insertion tube 1 passes. Cover plates 216 are glued or snapped onto the upper and lower sides of the through hole 212 on the adjustment seat 21 to protect the internal structure of the through hole 212; the cover plates 216 have holes for the insertion tube 1 to pass through, and the cover plates 216 are glued and fixed to the insertion tube 1, which can improve the stability of the adjustment seat 21 after installation.

[0030] The adjusting seat 21 has a threaded hole 213 inside. The axis of the threaded hole 213 is perpendicular to the depth direction of the through hole 212, and the threaded hole 213 communicates with the through hole 212. The screw 22 is threaded into the threaded hole 213, and one end of the screw 22 can be screwed into the through hole 212 and abut against the portion of the cannula 1 located inside the through hole 212. The driving assembly 23 is used to drive the screw 22 to rotate, thereby adjusting the degree of compression of the cannula 1 by the screw 22, so as to adjust the infusion volume of the cannula 1. The equivalent friction angle of the thread on the screw 22 is greater than the thread helix angle, so the screw 22 has a self-locking ability, making it difficult for the deformation of the cannula 1 itself to push the screw 22 to move.

[0031] Reference Figure 2 and Figure 3 The drive assembly 23 includes a connecting post 231, a plug rod 232, and a first elastic element 233. The connecting post 231 is coaxially fixedly connected to the end of the screw 22 away from the insertion tube 1. An annular insertion hole 2311 is provided on the end face of the connecting post 231. A limiting groove 2312 is provided on the inner wall of the insertion hole 2311. Multiple limiting grooves 2312 are provided and arranged in a circumferential array.

[0032] The adjusting seat 21 has an internal mounting hole 214 communicating with the threaded hole 213. The mounting hole 214 is coaxially located at the end of the threaded hole 213 away from the through hole 212. One end of the insertion rod 232 is located outside the mounting hole 214, and the other end of the insertion rod 232 is movably inserted into the mounting hole 214. The insertion rod 232 can slide axially relative to the mounting hole 214 and rotate about its own axis. A guide ring 2321 is coaxially fixedly connected to the end of the insertion rod 232 located inside the mounting hole 214. The guide ring 2321 is slidably connected to the mounting hole 214, thus preventing the insertion rod 232 from disengaging from the mounting hole 214. A handle 2322 is fixedly connected to the end of the insertion rod 232 located outside the mounting hole 214, thus facilitating the rotation of the insertion rod 232 by medical personnel.

[0033] The insertion rod 232 is located at the end of the connecting post 231 away from the screw 22, and a connector 4 is provided at the end of the insertion rod 232 near the connecting post 231. The connector 4 includes a connector ring 41, the inner wall of which is frustum-shaped, and the opening of the connector ring 41 at the end near the connecting post 231 is larger than the opening at the end away from the connecting post 231, thus facilitating the insertion of the connector ring 41 into the insertion hole 2311. An elastic limiting block 42 is fixedly connected to the inner wall of the connector ring 41. The number of limiting blocks 42 is the same as the number of limiting grooves 2312, and the multiple limiting blocks 42 are arranged in a circumferential array; the limiting blocks 42 can be inserted into the limiting grooves 2312 on the inner wall of the insertion hole 2311. Therefore, when the insertion ring 41 is inserted into the insertion hole 2311, the limiting block 42 is pressed against the limiting groove 2312. When the insertion rod 232 rotates, the connecting post 231 can be rotated through the cooperation of the insertion ring 41 and the insertion hole 2311. The connecting post 231 drives the screw 22 to rotate, thereby causing the screw 22 to be screwed in or out, so as to adjust the degree of compression of the insertion tube 1, thereby adjusting the infusion volume of the insertion tube 1.

[0034] The limiting block 42 is a flat block structure with a semi-circular cross-section, which makes it easy for the limiting block 42 to slide into the interior of the insertion hole 2311 along the axial direction; and when the limiting block 42 is pressed against the limiting groove 2312, the limiting block 42 is not easy to slide out of the limiting groove 2312 along the circumferential direction, so that the insertion ring 41 can rotate synchronously with the connecting post 231 better.

[0035] The first elastic element 233 is a spring, and it is coaxially arranged with the axis of the insertion rod 232. The first elastic element 233 is disposed between the insertion rod 232 and the connecting post 231. A rotating block (not shown in the figure) is provided at the first end of the first elastic element 233, and a rotating groove is provided at the end of the insertion rod 232. The rotating block is rotatably connected in the rotating groove, so that the first end of the first elastic element 233 is rotatably connected to the end of the insertion rod 232. The second end of the first elastic element 233 is fixedly connected to the end of the connecting post 231. In the initial state, the insertion ring 41 is located outside the insertion hole 2311, and the first elastic element 233 is in a compressed state. Therefore, even if the patient accidentally touches the handle 2322 at the end of the insertion rod 232, the slight sliding and rotation of the insertion rod 232 will not affect the state of the screw 22, thus ensuring the stability of the infusion volume. When it is necessary to adjust the infusion volume of the intubation tube 1, press the handle 2322 again. The handle 2322 drives the intubation rod 232 to move. The insertion ring 41 at the end of the insertion rod 232 is inserted into the insertion hole 2311 at the end of the connecting post 231. Then, by rotating the handle 2322, the limiting block 42 on the insertion ring 41 is screwed into the limiting groove 2312 on the insertion hole 2311. Then, by rotating the handle 2322, the screw 22 is driven to rotate, thereby realizing the adjustment of the infusion volume of the intubation tube 1.

[0036] When the limiting block 42 is inserted into the limiting groove 2312, its elastic clamping action secures the insertion ring 41 against the insertion hole 2311. Therefore, it is no longer necessary to continuously press the handle 2322; a slight rotation of the handle 2322 is sufficient to rotate the screw 22. As the screw 22 rotates, it moves along its axis, causing the connecting post 231 to move. The connecting post 231, in turn, moves the insertion ring 41, which is engaged within the connecting post 231. This causes the insertion rod 232 connected to the insertion ring 41 and the handle 2322 to move together, ensuring that the rotation of the handle 2322 is continuously transmitted to the screw 22, guaranteeing smooth screw insertion and removal. In other words, during adjustment, medical personnel do not need to continuously press and rotate the handle 2322; they only need to initially press the handle 2322 to initiate the insertion, and then rotate it for adjustment, simplifying the operation and making it more convenient.

[0037] In addition, the length of the insertion ring 41 in the axial direction is greater than the depth of the insertion hole 2311. Therefore, when the insertion ring 41 is fully inserted into the insertion hole 2311, a gap is formed inside the insertion ring 41 that can accommodate the first elastic member 233, thereby ensuring the insertion effect between the insertion ring 41 and the connecting post 231.

[0038] Reference Figure 4 To ensure the effective pressure of the screw 22 on the insertion tube 1, a stop block 3 is rotatably connected to the end of the screw 22 near the insertion tube 1. A guide post 31 is fixedly connected to the end of the stop block 3 near the screw 22. A guide groove 215 is provided inside the adjusting seat 21, and the guide post 31 slides through the guide groove 215, allowing the stop block 3 to slide against the adjusting seat 21. Therefore, as the screw 22 rotates, it can move along its own axis, causing the stop block 3 to move axially with the screw 22, thus pressing against the outer wall of the insertion tube 1. Since the stop block 3 does not rotate with the screw 22, the effective pressure on the insertion tube 1 is ensured.

[0039] In existing technology, the infusion volume is adjusted by squeezing the cannula 1 with a roller. When the roller squeezes the cannula 1 for an extended period, the material of the cannula 1 undergoes plastic deformation due to stress relaxation. When medical staff need to increase the flow rate and adjust in the opposite direction, releasing the roller, the cannula 1, due to the rebound hysteresis effect, cannot immediately overcome the adhesive force and return to its circular cross-section. This results in a slow actual flow rate response, exhibiting significant hysteresis, although the flow adjustment action is completed. This makes accurate titration extremely difficult, forcing medical staff to repeatedly check and readjust the flow to ensure a stable infusion volume.

[0040] To address this issue, healthcare professionals often have to interrupt the adjustment process, manually pulling the IV tubing to displace it relative to the regulator, exposing the pressure point, and then manually kneading it to restore its shape. However, this manual approach has significant drawbacks: First, pulling the IV tubing can easily displace the needle, causing blood backflow or damage to the puncture site; second, this kneading process disrupts the continuity of flow titration, making precise adjustments extremely difficult.

[0041] Therefore, to mitigate the adverse effects of the lag in the aforementioned adjustment process, this scheme proposes an alternative approach. (Refer to...) Figure 4 , Figure 5 and Figure 6 Specifically, an abutment piece 5 is provided on each side of the abutment block 3. In this embodiment, the end of the abutment piece 5 is rotatably connected to the abutment block 3, so the abutment piece 5 can swing relative to the abutment block 3; the two abutment pieces 5 are respectively located on both sides of the insertion tube 1, and are used to press against the side walls of both sides of the insertion tube 1. A second elastic element 6 is connected between the abutment piece 5 and the abutment block 3. The second elastic element 6 is a torsion spring. Under normal conditions, the second elastic element 6 is in an untwisted state, and the two abutment pieces 5 abut against the outer walls of both sides of the bulging insertion tube 1. Among them, the ends of the two abutment pieces 5 away from the abutment block 3 are flared, so the abutment pieces 5 will not abut against the inner wall of the perforation 212 during the swinging process, thereby avoiding the problem that the screw 22 cannot be screwed in due to the abutment pieces 5 abutting against the inner wall of the perforation 212.

[0042] In use, when screw 22 is screwed in, it pushes the abutment block 3 towards the side closer to the cannula 1. As the abutment block 3 moves, it compresses the cannula 1, increasing its deformation. The deformed cannula 1 pushes the abutment pieces 5 outward, i.e., the two abutment pieces 5 swing away from each other, thus providing more space for the deformation of the cannula 1; at this time, the second elastic element 6 is twisted. When screw 22 is screwed out, it pulls the abutment block 3 away from the side of the cannula 1. As the abutment block 3 moves, under the action of the second elastic element 6, it causes the two abutment pieces 5 to swing towards each other. Thus, the compression of the cannula 1 by the abutment block 3 accelerates the bulging of the cannula 1, thereby quickly opening the flow channel, increasing the infusion volume, and eliminating the lag in the adjustment process.

[0043] The implementation principle of Example 1 is as follows: When it is necessary to reduce the flow rate, press the handle 2322 inward, causing the handle 2322 to push the insertion rod 232 to move. The insertion ring 41 at the end of the insertion rod 232 is inserted into the insertion hole 2311 on the connecting post 231. Then, rotating the handle 2322 will cause the limiting block 42 on the insertion ring 41 to screw into the limiting groove 2312 on the inner wall of the insertion hole 2311, connecting the handle 2322 to the screw 22. Next, rotating the handle 2322 will drive the screw 22 to rotate. While rotating, the screw 22 slides along its own axis. When the screw 22 moves inward, it squeezes the insertion tube 1 through the abutment block 3, and the insertion tube 1 gradually flattens, thus reducing the infusion volume of the insertion tube 1. During this process, as the insertion tube 1 flattens, the width of the insertion tube 1 increases, and the expanding tube wall pushes the abutment pieces 5 on both sides outward. At this time, the two abutment pieces 5 are spread out in a V-shape, which does not hinder the flattening and interception of the insertion tube 1.

[0044] When a larger flow rate is needed, the handle 2322 is rotated in the opposite direction, causing the screw 22 to move outward. The screw 22 drives the abutment block 3 to retract, reducing the pressure on the cannula 1 and increasing the infusion volume of the cannula 1. During this process, the second elastic elements 6 on both sides continuously apply an inward torsional force, causing the two abutment pieces 5 to actively close towards the middle, squeezing the wider side walls of the cannula 1 at this time. Due to the incompressibility of the liquid and the shape characteristics of the tube, the pressure on the sides causes the flat cross-section of the cannula 1 to bulge rapidly, thereby forcibly opening the flow channel and causing the flow rate to increase rapidly with the adjustment action, eliminating the lag in the adjustment process.

[0045] This embodiment also discloses a flow rate control method, including the following steps: Step S1: The operator presses the insertion rod 232 with his finger to overcome the elastic force of the first elastic element 233, so that the insertion part 4 slides into the insertion hole 2311 on the connecting post 231.

[0046] Step S2: Rotate the insertion rod 232 in one direction. The insertion rod 232, through the cooperation of the connector 4 and the connecting post 231, drives the screw 22 to screw inward. The screw 22 pushes the abutment block 3 to move closer to the insertion tube 1, and the abutment block 3 flattens the insertion tube 1, reducing the infusion volume. Rotate the insertion rod 232 in the opposite direction. The insertion rod 232, through the cooperation of the connector 4 and the connecting post 231, drives the screw 22 to screw outward. The screw 22 pulls the abutment block 3 to move away from the insertion tube 1, reducing the compression of the insertion tube 1 by the abutment block 3, and increasing the infusion volume.

[0047] Step S3: After adjusting to the target flow rate, the operator releases their finger, and the insertion rod 232 automatically pops out and resets under the action of the first elastic element 233, so that the insertion piece 4 disengages from the insertion hole 2311 to prevent accidental contact.

[0048] Example 2: Refer to Figure 7 and Figure 8The difference between this embodiment and Embodiment 1 is that, in this embodiment, the abutment block 3 has a sliding groove 32 inside, and a connecting block 7 is slidably connected to each end of the sliding groove 32. The connecting block 7 is fixedly connected to the end of the abutment piece 5. A third elastic element 8, which is a spring, is connected between the two connecting blocks 7. Under normal conditions, the third elastic element 8 is at its original length, and at this time, the two abutment pieces 5 abut against the outer walls of the two sides of the bulging insertion tube 1.

[0049] Therefore, when the screw 22 is screwed inward, it pushes the abutment block 3 to move closer to the cannula 1. At this time, the cannula 1 is flattened due to the pressure from the abutment block 3. The flattened cannula 1 pushes the abutment pieces 5 on both sides to move away from each other. The third elastic element 8 is stretched, so that the cannula 1 can be flattened smoothly and the liquid medicine inside the cannula 1 can be cut off better. When the screw 22 is screwed outward, it pulls the abutment block 3 to move away from the cannula 1. At this time, the pressure on the cannula 1 is reduced. At the same time, under the action of the third elastic element 8, the abutment pieces 5 on both sides will always be pressed against the sides of the cannula 1. That is, the two abutment pieces 5 will move towards each other, thereby squeezing the cannula 1 inward, so that the cannula 1 can recover from the flat cross section to the round cross section more quickly, thus increasing the infusion volume. That is, when the rotating handle 2322 is used for adjustment, the cannula 1, which has been flattened for a long time, can quickly return to its original shape, thereby eliminating the lag in the adjustment process.

[0050] Furthermore, to prevent excessive deformation of the abutment piece 5 during the compression of the insertion tube 1, the adjusting seat 21 is also provided with a receiving groove 211 for inserting the abutment piece 5, which is connected to the through hole 212. Therefore, during the screw 22 screwing in, the abutment block 3 moves inward, and the abutment block 3 drives the abutment piece 5 to move inward. At this time, the end of the abutment piece 5 can gradually slide into the receiving groove 211, thereby avoiding the end of the abutment piece 5 from abutting against the inner wall of the through hole 212, which would prevent the screw 22 from continuing to screw in.

[0051] The implementation principle of Example 2 is as follows: When the driving component 23 moves the abutment block 3 towards the side closer to the insertion tube 1 to flatten the insertion tube 1, the abutment piece 5 moves accordingly and enters the receiving groove 211. During the flattening process, the insertion tube 1 pushes the two abutment pieces 5 to overcome the pulling force of the third elastic element 8 and move towards the side away from each other. This action ensures that under the flow-blocking condition, the abutment pieces 5 actively give way, ensuring that the insertion tube 1 can be fully flattened to cut off the water flow and preventing the tube cavity from failing to close completely due to excessive lateral clamping force.

[0052] When the reverse adjustment is performed to move the abutment block 3 away from the insertion tube 1, the compression of the abutment block 3 on the insertion tube 1 is reduced, which weakens the support of the insertion tube 1 on the abutment piece 5. Therefore, under the action of the third elastic element 8, the two abutment pieces 5 together with the connecting block 7 slide towards each other, quickly clamping the side wall of the insertion tube 1, assisting the tube wall of the insertion tube 1 to quickly return to a round shape, thereby eliminating the lag in the adjustment process.

[0053] The above are optional embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made to the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A single-stage intravenous cannula with adjustable infusion volume, characterized in that, include: Intubation (1); The adjustment mechanism (2) includes an adjustment seat (21), a screw (22) and a drive assembly (23). The adjustment seat (21) is sleeved on the outside of the insertion tube (1). The screw (22) is threaded into the adjustment seat (21). The end of the screw (22) is used to abut against the outer wall of the insertion tube (1) located in the adjustment seat (21). The drive assembly (23) is used to drive the screw (22) to rotate. The drive assembly (23) includes a connecting post (231), a insertion rod (232), and a first elastic element (233). The connecting post (231) is connected to the end of the screw (22) away from the insertion tube (1). The insertion rod (232) is located at the end of the connecting post (231) away from the screw (22). One end of the insertion rod (232) is movably inserted into the adjusting seat (21). The end of the insertion rod (232) near the connecting post (231) is provided with a insertion point. The connector (4) has a socket (2311) on the connecting post (231) for inserting the connector (4) into the socket (2311). When the plug rod (232) rotates, it drives the screw (22) to rotate. The first elastic element (233) is connected to the plug rod (232). The first elastic element (233) is used to drive the plug rod (232) to slide away from the connecting post (231).

2. The single-stage venous catheter with adjustable infusion volume according to claim 1, characterized in that: The connector (4) includes a connector ring (41), the inner wall of which is frustum-shaped. The opening of the connector ring (41) near the connecting post (231) is larger than the opening of the connector ring (41) away from the connecting post (231). A limiting block (42) is provided on the inner wall of the connector ring (41). The limiting block (42) is elastic. The insertion hole (2311) is annular and adapted to the connector ring (41). A limiting groove (2312) is provided on the inner wall of the insertion hole (2311) for the limiting block (42) to be inserted.

3. The single-stage venous catheter with adjustable infusion volume according to claim 1, characterized in that: The axis of the first elastic element (233) is coaxial with the axis of the insertion rod (232), the first end of the first elastic element (233) is rotatably connected to the insertion rod (232), and the second end of the first elastic element (233) is connected to the connecting post (231).

4. The single-stage venous catheter with adjustable infusion volume according to claim 1, characterized in that: The insertion rod (232) has a handle (2322) at one end outside the adjustment seat (21).

5. A single-stage venous catheter with adjustable infusion volume according to claim 1, characterized in that: The end of the screw (22) is rotatably connected to an abutment block (3), which is slidably connected to the adjusting seat (21) and is used to abut against the insertion tube (1).

6. A single-stage venous catheter with adjustable infusion volume according to claim 5, characterized in that: The abutting block (3) is provided with abutting pieces (5) on both sides. The two abutting pieces (5) are used to press against the opposite sides of the outer peripheral surface of the insertion tube (1). When the abutting block (3) moves closer to the insertion tube (1), the two abutting pieces (5) move away from each other. When the abutting block (3) moves away from the insertion tube (1), the two abutting pieces (5) move closer to each other.

7. A single-stage venous catheter with adjustable infusion volume according to claim 6, characterized in that: The abutting piece (5) and the abutting block (3) are rotatably connected. A second elastic element (6) is connected between the abutting piece (5) and the abutting block (3). The second elastic element (6) is used to drive the two abutting pieces (5) to swing towards each other. The ends of the two abutting pieces (5) away from the abutting block (3) are flared.

8. A single-stage venous catheter with adjustable infusion volume according to claim 6, characterized in that: Each of the abutting pieces (5) is provided with a connecting block (7), the connecting block (7) is slidably connected to the abutting block (3), and a third elastic member (8) is connected between the two connecting blocks (7). The third elastic member (8) is used to drive the two connecting blocks (7) to slide towards each other. The adjusting seat (21) is provided with a receiving groove (211) for the abutting piece (5) to be inserted.

9. A flow rate control method, characterized in that: The flow rate control method, using a single-stage venous cannula with adjustable infusion volume as described in any one of claims 1 to 8, comprises the following steps: Step S1: Press the plug rod (232) to insert the plug (4) into the socket (2311); Step S2: Rotate the insertion rod (232), which drives the connecting post (231) and the screw (22) to rotate, and the end of the screw (22) presses against the insertion tube (1). Step S3: Pull out the insert rod (232) to disengage the plug (4) from the socket (2311), and the first elastic member (233) presses against the insert rod (232).

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